CN114071376B

CN114071376B - Communication method, device and system

Info

Publication number: CN114071376B
Application number: CN202110858677.9A
Authority: CN
Inventors: 贾建鑫; 吴问付; 宗在峰
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-08-03
Filing date: 2021-07-28
Publication date: 2023-04-04
Anticipated expiration: 2041-07-28
Also published as: CN114071376A

Abstract

The embodiment of the application discloses a communication method, a communication device and a communication system, so that normal transmission of data of a multicast service is kept under the condition of deactivating/deactivating a multicast session, and continuity of the multicast service is realized. The method comprises the following steps: the first session management function network element or the access network equipment determines whether the PDU session to be deactivated is associated with the multicast session corresponding to the multicast service, if so, the PDU session is deactivated when the multicast session is deactivated, otherwise, the PDU session is not deactivated if the multicast session is in an activated state.

Description

Communication method, device and system

The present application claims priority from the chinese patent application entitled "a method, apparatus and system for communication" filed by the national intellectual property office at 03/08/03/2020, application No. 202010769176.9, the entire contents of which are incorporated herein by reference.

Technical Field

The embodiment of the application relates to the technical field of communication, in particular to a communication method, device and system.

Background

With the development of mobile internet, the mobile high-definition video service presents a blowout situation. The user gradually changes from the traditional mode of watching the hot spot program through a fixed television to the mode of watching the hot spot program through a mobile phone terminal and a mobile internet, and the impact of the video service on the mobile network is stronger. At present, the impact of video traffic on a mobile network can be greatly reduced by optimizing the transmission of video services in a multicast/broadcast (multicast/broadcast) manner, for example, data of the video services are sent to a large number of users in a multicast/broadcast manner.

Among many mobile communication network architectures, the 5th generation (5g) mobile communication network architecture can support multicast/broadcast functions, and send data of multicast/broadcast services to a large number of users in a multicast/broadcast manner. In the research on the multicast/broadcast function of 5G, how to keep normal transmission of multicast service data under the activation and deactivation of the multicast/broadcast session to achieve continuity of the multicast service is a problem to be solved urgently.

Disclosure of Invention

Embodiments of the present application provide a communication method, apparatus, and system, so as to solve a problem how to maintain normal transmission of data of a multicast service to implement continuity of the multicast service under activation and deactivation of a multicast/broadcast session.

In order to achieve the above purpose, the following technical solutions are adopted in the embodiments of the present application.

In a first aspect of the embodiments of the present application, a communication method is provided, where the method may be performed by a first session management function network element or an access network device, and the method includes: determining whether the PDU session to be deactivated is associated with a multicast session corresponding to the multicast service, determining whether the multicast session is in an activated state, if the PDU session is associated with the multicast session and the multicast session is in the activated state, keeping the state of the PDU session in the activated state, and if the PDU session is associated with the multicast session and the multicast session is in the deactivated state, deactivating the PDU session.

Based on the method described in the first aspect, when a PDU session is deactivated, the activation condition of a multicast session associated with the PDU session is checked, and if the multicast session associated with the PDU session is in an activated state, the PDU session is not deactivated, and the PDU session is maintained in the activated state, so that data of a multicast service is subsequently mapped/injected onto the PDU session in a certain application scenario (for example, a switching scenario), thereby ensuring normal transmission of data of the multicast service, or, when the PDU session is the last PDU of a terminal, the terminal enters an idle state after the PDU session is deactivated, thereby causing a problem that the terminal cannot receive data of the multicast service through an air interface resource. If the multicast session associated with the PDU session is in a deactivated state, the PDU session is deactivated, transmission resources are saved, and the resource utilization rate is improved.

In one possible design, if the main execution body of the method is a first session management function network element, the first session management function network element corresponds to a first terminal, and the first terminal belongs to a multicast group corresponding to a multicast service, determining whether the multicast session is in an active state includes: the first session management function network element receives first information from the second session management function network element, where the first information is used to indicate that the multicast session is deactivated, and for example, the first information may be any one of the following information: the multicast/broadcast service session stop (MBS session stop), the multicast/broadcast service session deactivation (MBS session deactivation), or the multicast session deactivation (multicast session deactivation), the second session management functional network element corresponds to the multicast group, and the first session management functional network element determines that the multicast session is in the deactivated state according to the first information.

Based on the possible design, when the multicast session is stopped or otherwise deactivated, the second session management function network element managing the multicast session notifies the first session management function network element to deactivate the multicast session in time, so that the first session management function network element judges and releases the PDU session associated with the deactivated multicast session in combination with the multicast session, thereby making the state of the PDU session consistent with the state of the multicast session associated therewith, and ensuring that the available session enables normal transmission of data of the multicast service.

In one possible design, the method further includes: the first session management function network element receives second information used for indicating activation of the multicast session from the second session management function network element, and the second information may be any one of the following information: a multicast/broadcast service session start/start (MBS session start), a multicast broadcast service session activation (MBS session activation), or a multicast session activation (multicast session activation), the first session management functional network element notifies the access network device to add the first terminal to the multicast group, for example, the first session management functional network element may notify the access network device to add the first terminal to the multicast group through N2 session management information (N2 SM information), the N2 SM information may be a PDU session resource establishment request transmission (PDU session resource request) or a PDU session resource establishment request (PDU session resource request) or a PDU session resource modification request transmission (PDU session resource modification request) or a PDU session resource modification request transmission (PDU modification request). The N2 SM information includes identification information of a multicast service (for example, identification information of a multicast broadcast service session (MBS session)); optionally, the N2 SM information may further include an instruction to join the terminal into the multicast session; optionally, the N2 SM information may further include unicast QoS configuration information mapped/corresponding to QoS configuration (QoS profile) information of a multicast service corresponding to the multicast session.

Based on the possible design, the first session management function network element may restart the multicast session under the instruction of the second session management function network element, trigger the access network device to add the first terminal to the multicast group corresponding to the multicast session, and transmit data in a multicast manner, thereby improving the resource utilization rate.

In a possible design, a first session management function network element notifies an access network device that a PDU session associated with a multicast session is in a deactivated state before joining a first terminal to a multicast group, and then the method further includes: the first session management function network element activates a PDU session associated with a multicast session, which may also be called a multicast session.

In another possible design, after the first session management function network element notifies the access network device to join the first terminal device to the multicast group, if a PDU session associated with the multicast session is in a deactivated state, the method further includes: and the first session management function network element activates the PDU session related to the multicast session.

Based on the possible design, when the multicast session is in an active state, the associated PDU session can be activated, so that the state of the PDU session is consistent with that of the associated multicast session, and it is ensured that the available session enables normal transmission of data of the multicast service.

In one possible design, the method further comprises: and the first session management function network element determines to transmit the data of the multicast service through the PDU session. Based on the possible design, when the multicast session is in a deactivated state, the multicast service can be mapped to the PDU session, and the data of the multicast service is transmitted through the PDU session, so that the data transmission continuity of the multicast service is ensured.

In one possible design, the method further comprises: the first session management function network element sends third information used for indicating and detecting data of the multicast service sent by the second user plane function network element to the first user plane function network element, the first session management function network element receives fourth information used for indicating and detecting the data of the multicast service from the first user plane function network element, and the first session management function network element informs the access network equipment to add the first terminal into the multicast group.

Based on the possible design, under the condition that the multicast service is mapped to the PDU session, the first user plane network element is informed to detect whether the data of the multicast service sent from the second user plane network element exists or not at the moment, if so, the first user plane network element is informed to the first session management function network element, the first session management function network element is triggered to activate the multicast session, the data is transmitted through the multicast session, and the resource utilization rate and the data transmission rate are improved.

In one possible design, if the main execution body of the method is AN access network device, before the access network device initiates the access network to release AN release, the access network device determines whether the PDU session is associated with the multicast session.

Based on the possible design, before the access network device initiates AN release flow, it may be determined whether a PDU session, especially the last PDU session of the terminal, is associated with the multicast session, so as to initiate AN release flow without considering the multicast session, so that the terminal is in a CM idle state, and data transmission of the multicast service is affected.

In one possible design, before determining whether the PDU session is associated with the multicast session, if the execution subject of the method is an access network device, the method further includes: the access network equipment receives fifth information of the first session management function network element for indicating the deactivation of the PDU session, and if the PDU session state is kept to be an activated state, the method further comprises the following steps: the access network equipment sends sixth information for indicating to reject to deactivate the PDU session to the first session management function network element; if the PDU session is deactivated, the method further comprises: and the access network equipment sends seventh information for indicating that the PDU session is deactivated to the first session management function network element. Based on the possible design, after determining the status of the PDU session, the access network device may send sixth information or seventh information to the first session management function network element, so that the first session management function network element synchronizes the current status of the PDU.

In a second aspect, an embodiment of the present application provides a communication method, which may be performed by a first session management function network element or an access network device, where the method includes: determining whether the PDU session to be deactivated is associated with a multicast session corresponding to the multicast service, determining whether the multicast session is in an activated state, and determining whether the access network equipment corresponding to the PDU session to be deactivated supports a multicast function; if the PDU session is associated with the multicast session, the multicast session is in an activated state, and the access network equipment does not support the multicast function, the PDU session is kept in the activated state; and if the PDU session is associated with the multicast session and the multicast session is in a deactivated state, deactivating the PDU session.

Based on the method described in the second aspect, when a PDU session is deactivated, the activation condition of a multicast session associated with the PDU session and whether an access network device corresponding to the PDU session supports a multicast function may be checked, and if the multicast session associated with the PDU session is in an activated state and the access network device does not support the multicast function, the PDU session is not deactivated, and the PDU session is maintained in the activated state, so that data of a multicast service is mapped/injected onto the PDU session in a certain application scenario (for example, a switching scenario) in the following process, so as to ensure normal transmission of data of the multicast service, or, when the PDU session is the last PDU of a terminal, the terminal enters an idle state after the PDU session is deactivated, so that the terminal cannot receive data of the multicast service through an air interface resource. If the multicast session associated with the PDU session is in a deactivated state, the PDU session is deactivated, transmission resources are saved, and the resource utilization rate is improved.

In a possible design, if the main execution body of the method is a first session management function network element, the first session management function network element corresponds to a first terminal, and the first terminal belongs to a multicast group corresponding to a multicast service, determining whether the multicast session is in an active state includes: and the first session management function network element receives the first information from the second session management function network element and determines that the multicast session is in a deactivated state according to the first information. The first information is used for indicating the deactivation of the multicast session, and the second session management function network element corresponds to the multicast group.

Based on the possible design, when the multicast session stops or other multicast sessions are deactivated, the second session management function network element for managing the multicast session notifies the first session management function network element to deactivate the multicast session in time, so that the first session management function network element judges and releases the PDU session associated with the deactivated multicast session under the condition of combining the multicast session, the state of the PDU session and the multicast session associated with the PDU session is consistent, and the available session is ensured to enable the data of the multicast service to be normally transmitted.

In one possible design, the method further comprises: the first session management function network element receives second information from the second session management function network element, wherein the second information is used for indicating the activation of the multicast session; and the first session management function network element informs the access network equipment to add the first terminal into the multicast group.

Based on the possible design, the first session management function network element can acquire the activation of the multicast session under the indication of the second session management function network element, trigger the access network device to add the first terminal into the multicast group corresponding to the multicast session, and transmit data in a multicast mode, thereby improving the resource utilization rate.

In a third aspect, the present application provides a communication apparatus, which may be a first session management function network element on a first session management function network element or a chip or a system on chip in the first session management function network element. Alternatively, the communication device may be an access network device on an access network device or a chip or system on chip in an access network device. The communication means may implement the functions performed by the communication means in the possible designs of the first aspect or the first aspect described above, or the functions performed by the communication means in the apparatus of the second aspect or the second aspect. The functions can be realized by hardware, and the functions can also be realized by executing corresponding software by hardware. The hardware or software comprises one or more modules corresponding to the functions.

In one possible design, such as: the communication apparatus may include: and a processing unit.

And the processing unit is used for determining whether the PDU session to be deactivated is associated with the multicast session corresponding to the multicast service, determining whether the multicast session is in an activated state, if the PDU session is associated with the multicast session and the multicast session is in the activated state, keeping the PDU session in the activated state, and if the PDU session is associated with the multicast session and the multicast session is in the deactivated state, deactivating the PDU session.

For a specific implementation manner of each unit of the communication apparatus, reference may be made to the first session management function network element or function in the communication method provided by the first aspect or any one of the possible designs of the first aspect, and details are not repeated here. The communication device provided may achieve the same advantageous effects as the first aspect or any one of the possible designs of the first aspect.

In yet another possible design, the communication device includes: a processor and a memory; the memory is configured to store computer-executable instructions that, when executed by the communication device, cause the communication device to perform the communication method as set forth in the first aspect or any one of the possible designs of the first aspect.

In a fourth aspect, a computer-readable storage medium is provided, having instructions stored thereon, which, when run on a computer, cause the computer to perform the communication method of the first aspect or any one of the possible designs of the above aspect.

In a fifth aspect, there is provided a computer program product comprising instructions which, when run on a computer, cause the computer to perform the communication method of the first aspect described above or any one of the possible designs of the above aspect.

In a sixth aspect, a communications device is provided, which may be a system on chip, and the system on chip may include a processor and a communications interface, and is configured to support the communications device to implement the functions involved in the first aspect or any one of the possible designs of the first aspect, for example, the processor determines whether a PDU session to be deactivated is associated with a multicast session corresponding to a multicast service, determines whether the multicast session is in an active state, and if the PDU session is associated with the multicast session and the multicast session is in the active state, keeps the state of the PDU session in the active state, and if the PDU session is associated with the multicast session and the multicast session is in the inactive state, deactivates the PDU session. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the communication device. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

For technical effects brought by any design manner in the third aspect to the sixth aspect, reference may be made to the technical effects brought by the first aspect or any possible design manner in the first aspect, and details are not repeated.

In a seventh aspect, an embodiment of the present application provides another communication method, where the method may include: and the first session management function network element receives second information which is used for indicating the activation of the multicast session and is from the second session management function network element, and informs the access network equipment to add the first terminal to a multicast group corresponding to the multicast session, wherein the first session management function network element corresponds to the first terminal, and the second session management function network element corresponds to the multicast group.

Based on the method in the seventh aspect, when the multicast session is in the deactivated state, after receiving the second information for activating the multicast session, the first session management function network element notifies the access network device to add the first terminal to the multicast group corresponding to the multicast session, and transmits the data of the multicast service through the multicast session, so as to activate the multicast session, and send the data of the multicast service to the terminal through the multicast session, thereby improving the resource utilization rate.

In one possible design, the method further includes: and activating the PDU session associated with the multicast session.

Based on the possible design, when a multicast session is activated, the activation condition of the PDU session associated with the multicast session can be checked, and if the PDU session is inactive, the PDU session is activated, so that data of the multicast service is mapped/injected onto the PDU session subsequently under a certain application scenario (for example, a handover scenario), and normal transmission of the data of the multicast service is ensured.

In one possible design, the method further includes: and if the access network equipment corresponding to the PDU session associated with the multicast session does not support the multicast function, the first session management function network element activates the PDU session.

Based on the possible design, when the multicast session is in an activated state, the PDU session associated with the multicast session can be activated according to the capability, so that the state of the PDU session is consistent with that of the multicast session associated with the PDU session, and the available session is ensured to ensure that the data of the multicast service is normally transmitted.

It should be noted that, in this embodiment of the application, after receiving the second information for activating the multicast session, the first session management function network element may execute one or two of the following two processes: (1) Informing the access network equipment to add the first terminal to a multicast group corresponding to the multicast session; (2) Activating the PDU session related to the multicast session according to the second information; or, when the access network device corresponding to the PDU session associated with the multicast session does not support the multicast function, the first session management function network element activates the PDU session according to the second information. It should be noted that, when the two processes are executed, the order of the two execution processes is not limited, and the process (1) may be executed according to the second information, and further optionally, the process (2) may be executed again; or, the process (2) is executed according to the second information, and the process (1) is further optionally executed.

In one possible design, activating a PDU session for multicast session association may include: after the first session management function network element receives the second information for activating the multicast session, the first session management function network element sends a naf _ Communication _ N1N2message transfer message containing an N2 session management message (N2 SM information) or a PDU session context update Response (Nsmf _ PDU _ uplink smcontext Response) containing an N2 SM information to the access network device, so as to trigger the access network device to activate a PDU session associated with the multicast session according to the N2 SM information, for example, to establish an air interface resource and a transmission tunnel (which may be referred to as a tunnel for short in this application) corresponding to the PDU session. Further, after activating the PDU session associated with the multicast session, the access network device may also send a reply message for the N2 SM information to the first session management function network element.

Wherein, the N2 SM information may be a PDU session resource setup request transmission (PDU session resource setup request transfer), and the reply message for the N2 SM information may be a PDU session resource setup reply transmission (PDU session resource setup request transfer); or the N2 SM information may be a PDU session resource setup request (PDU session resource setup request), and the reply message for the N2 SM information may be a PDU session resource setup reply (PDU session resource setup response); alternatively, the N2 SM information may be a PDU session resource modification request transmission (PDU session resource modification request transfer), and the reply message for the N2 SM information may be a PDU session resource modification reply transmission (PDU session resource modification request transfer); alternatively, the N2 SM information may be a PDU session resource modification request (PDU session resource modification request), the reply message for the N2 SM information may be a PDU session resource modification reply (PDU session resource modification response), and the like, without limitation.

The N2SM information may include identification information of a multicast service (e.g., identification information of a multicast broadcast service session (MBS session)). Optionally, the N2SM information may further include an instruction to join the terminal into the multicast session; optionally, the N2SM information may further include unicast QoS configuration information mapped/corresponding to QoS configuration (QoS profile) information of a multicast service corresponding to the multicast session.

If the N2SM information includes unicast QoS configuration information mapped/corresponding to QoS configuration (QoS profile) information of a multicast service corresponding to a multicast session, the access network device may configure an air interface resource (or referred to as a radio bearer) for transmitting data of the multicast service according to the unicast QoS configuration information, and after the air interface resource is established, if a transmission tunnel between the access network device and the UPF is not established, the access network device includes, in a reply message to the N2SM information sent to the first session management function network element, downlink tunnel information (such as an NG-U transport layer information or an NG-node end point), where the downlink tunnel information is a necessary cell in the reply message of the N2SM information, and the downlink tunnel information may be used to establish a transmission tunnel for transmitting data of the multicast service between the access network device and the UPF, and it is ensured that a PDU session associated with the multicast session is activated.

In one possible design, the method further comprises: and the first session management function network element sends identification information of the multicast group to the first access and mobility management function network element, wherein the identification information of the multicast group is used for initiating group paging in a registration area of the first terminal when the first access and mobility management function network element finds that the first terminal is in an idle state.

Further, the first access and mobility management function network element receives the identifier information of the multicast group sent by the first session management function network element, and if there is a CM-IDLE terminal in the multicast group, in a registration area of the CM-IDLE terminal, sends a paging message (which may be referred to as a group paging message) carrying the identifier information of the multicast group to the access network device, and triggers the access network device to page a plurality of terminals in the CM-IDLE state in the multicast group.

The terminal in the CM-IDLE state in the multicast group may include the first terminal, and may further include other terminals, such as a second terminal, a third terminal, and the like.

It should be noted that, when there are multiple terminals in the CM-IDLE state in the multicast group and there are areas where registration areas of the multiple terminals overlap with each other (which may be referred to as overlapping areas herein), in order to save signaling overhead, the first access and mobility management function network element may initiate group paging in the overlapping area of one terminal without repeatedly initiating group paging in the overlapping area of the registration area of each terminal. For example, a second terminal in a CM-IDLE state also exists in the multicast group, and the identification information of the multicast group is further used for initiating group paging in an area other than an overlapping area in the registration area of the second terminal when the first access and mobility management function network element finds that the second terminal is in an IDLE state, where the overlapping area may be an area where the registration area of the first terminal and the registration area of the second terminal overlap each other.

Based on the possible design, the first session management function network element may send the identification information of the multicast group to the first access and mobility management function network element, and the first access and mobility management function network element receives the identification information of the multicast group and finds that the first terminal is in the CM-IDLE state, then the first access and mobility management function network element initiates a group paging to the access network device in the first terminal device registration area, for example, sends a message carrying the identification information of the multicast group for paging a plurality of terminals in the CM-IDLE state in the multicast group, it should be noted that the first access and mobility management function network element does not repeatedly initiate a group paging in an overlapping area of the registration area of each of the plurality of terminals in the CM-IDLE state in the multicast group, thereby reducing signaling overhead.

The identification information of the multicast group may also be referred to as identification information of a multicast session (multicast session), or may also be referred to as identification information of a multicast broadcast session (MB session), or may also be referred to as identification information of a multicast broadcast service session (MBs session), and the identification information of the multicast group may include: TMGI, identifier of multicast service, multicast address, multicast IP address (IP multicast address), identifier of multicast group, identifier of multicast session, context information of multicast session, address information of multicast service, identifier of PDU session associated with multicast session, one or more of multicast/broadcast service session ID (MBS session ID), multicast session ID (multicast session ID), multicast service session ID (multicast service session ID), and identifier of Service Data Flow (SDF) of multicast service, and the identifier of multicast group may be the same as the identifier of multicast service, without limitation.

In another possible design, the method further includes: the first session management function network element sends a third message to the first access and mobility management function network element, where the third message may be an N11 message, and the third message may include identification information of the first terminal, and the third message may be used to trigger the first access and mobility management network element to initiate paging in a registration area of the first terminal when the first terminal is in an idle state.

For example, when the first terminal is in an IDLE state (or referred to as an IDLE state or a CM-IDLE state), the first access and mobility management network element sends, in a registration area of the first terminal in the CM-IDLE state, a paging message for the first terminal to the access network device, and triggers the access network device to page the first terminal in the CM-IDLE state.

The identification information of the first terminal may be used to identify the first terminal, and the identification of the first terminal may include a user permanent identifier (SUPI) of the first terminal, a general public user identifier (GPSI) of the first terminal, or a user hidden identifier (SUCI). The first access and mobility management function network element may be an access and mobility management function network element serving the NAS signaling of the first terminal, or may also be an access and mobility management function network element serving the multicast group, which is not limited.

In one possible design, the method further comprises: the first session management function network element receives first information used for indicating that the multicast session is deactivated from the second session management function network element, for example, the first information may be multicast/broadcast service session stop (MBS session stop) or multicast broadcast service session deactivation (multicast session deactivation), and the first session management function network element marks the multicast session as a deactivated state according to the first information.

Based on the possible design, when the multicast session is stopped or otherwise deactivated, the second session management function network element managing the multicast session may notify the first session management function network element to deactivate the multicast session in time, so that the first session management function network element marks the state of the multicast session. The subsequent first session management function network element may determine whether to deactivate the associated PDU session according to the marked state of the multicast session.

In one possible design, the method further includes: and the first session management function network element determines to transmit the data of the multicast service through the PDU session related to the multicast session. Based on the possible design, when the multicast session is in a deactivated state, the multicast service is mapped to the PDU session, and the data of the multicast service is transmitted through the PDU session, so that the data transmission continuity of the multicast service is ensured.

In one possible design, the method further comprises: and the first session management functional network element sends third information used for indicating and detecting the data of the multicast service sent by the second user plane functional network element to the first user plane functional network element, receives fourth information used for indicating and detecting the data of the multicast service from the first user plane functional network element, and informs the access network equipment to add the first terminal into the multicast group.

Based on the possible design, under the condition that the multicast service is mapped to the PDU session, the first user plane network element is informed to detect whether the data of the multicast service sent from the second user plane network element exists at any moment, if so, the first user plane network element is informed to the first session management function network element, the first session management function network element is triggered to activate the multicast session, the data of the multicast service is transmitted through the multicast session, and the resource utilization rate is improved.

In one possible design, the method further includes: after the first terminal joins in the multicast group corresponding to the multicast session, the first session management function network element releases the resource of the data of the multicast service transmitted through the PDU session, reduces the resource occupation and improves the resource utilization rate.

In an eighth aspect, a communication apparatus is provided, which may be a first session management function network element or a chip or a system on chip in the first session management function network element. The communication apparatus may implement the function performed by the first session management function network element in the seventh aspect or the possible design of the seventh aspect, where the function may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or software comprises one or more modules corresponding to the functions. Such as: the communication apparatus may include: a receiving unit and a processing unit;

a receiving unit, configured to receive second information indicating that the multicast session is activated from the second session management function network element.

And the processing unit is used for informing the access network equipment to add the first terminal into a multicast group corresponding to the multicast session, wherein the first session management function network element corresponds to the first terminal, and the second session management function network element corresponds to the multicast group.

A specific implementation manner of the communication apparatus may refer to a behavior function of a first session management function network element in a communication method provided by any one of the seventh aspects or possible designs of the seventh aspects, and any one of the seventh aspects or any one of the possible design methods of the seventh aspects may be correspondingly implemented by a receiving unit and a sending unit included in the communication apparatus.

In a ninth aspect, there is provided a communication apparatus comprising: a processor and a memory; the memory is configured to store computer-executable instructions, and when the communication apparatus is running, the processor executes the computer-executable instructions stored in the memory to enable the communication apparatus to perform the communication method according to any one of the possible designs of the seventh aspect or the seventh aspect.

A tenth aspect provides a computer-readable storage medium having stored therein instructions, which, when run on a computer, cause the computer to perform the communication method of the seventh aspect or any one of the above possible designs.

In an eleventh aspect, there is provided a computer program product comprising instructions which, when run on a computer, cause the computer to perform the communication method of the seventh aspect described above or any one of the possible designs of the above aspects.

In a twelfth aspect, a chip system is provided, where the chip system includes a processor and a communication interface, and is configured to enable a communication device to implement the functions in the foregoing aspects, for example, the processor receives, through the communication interface, second information from a second session management function network element, where the second information indicates that a multicast session is activated, and notifies an access network device to join a first terminal to a multicast group corresponding to the multicast session, where the first session management function network element corresponds to the first terminal, and the second session management function network element corresponds to the multicast group. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the communication device. The chip system may be formed by a chip or include a chip and other discrete devices.

For technical effects brought by any design manner of the ninth aspect to the twelfth aspect, reference may be made to the seventh aspect or any possible design manner of the seventh aspect, and details are not repeated.

In a thirteenth aspect, there is also provided a communication method, including: the method comprises the following steps: the access network device determines to deactivate a multicast session corresponding to the multicast service, and sends eighth information used for indicating the deactivation of the multicast session to a first access and mobility management function network element or a second access and mobility management function network element, where the first access and mobility management function network element corresponds to a terminal in a multicast group corresponding to the multicast service, and the second access and mobility management function network element corresponds to the multicast group corresponding to the multicast service.

Based on the method in the thirteenth aspect, after the access network device determines to deactivate the multicast session, the access network device sends the information for deactivating the multicast session to the core network side device, so that the core network side device deactivates the multicast session according to the information sent by the access network device, and resource overhead is saved.

In one possible design, the determining, by the access network device, to deactivate the multicast session of the multicast service includes: if the time length that the access network equipment does not receive the data of the multicast service on the multicast session is longer than the preset time length, the access network equipment determines to deactivate the multicast session of the multicast service. Or, if there is no terminal receiving the data of the multicast service in the terminals served by the access network device, the access network device determines to deactivate the multicast session of the multicast service. Based on the possible design, the multicast session is deactivated when the data of the multicast service is not transmitted or no terminal receives the data of the multicast service, so as not to influence other terminals to receive the data of the multicast service.

In a possible design, the eighth information is further used to notify a transmission tunnel releasing the multicast session, reduce occupation of the transmission tunnel, and improve resource utilization.

In one possible design, the eighth information includes identification information of the multicast session, and the identification information of the multicast session includes one or more of identification information of the multicast session, identification information of the multicast service, context information of the multicast session, address information of the multicast service, identification information of a PDU session associated with the multicast session, and identification information of a service data stream SDF of the multicast service. Based on the possible design, the multicast session can be indicated by combining various information, and the method is flexible and various and has a wide application range.

In one possible design, the air interface resources corresponding to the multicast session are released, so that the resource occupation is reduced, and the resource utilization rate is improved.

In a fourteenth aspect, the present application provides a communication apparatus, which may be an access network device or a chip or a system on chip in the access network device. The communication device may implement the functions performed by the access network equipment in the above thirteenth aspect or the possible designs of the thirteenth aspect, and the functions may be implemented by hardware or by hardware executing corresponding software. The hardware or software comprises one or more modules corresponding to the functions. Such as: the communication apparatus may include: a processing unit, a transmitting unit;

And the processing unit is used for determining the multicast session corresponding to the deactivated multicast service.

A sending unit, configured to send eighth information used for indicating to deactivate the multicast session to the first access and mobility management function network element or the second access and mobility management function network element, where the first access and mobility management function network element corresponds to a terminal in a multicast group corresponding to the multicast service, and the second access and mobility management function network element corresponds to the multicast group corresponding to the multicast service.

The specific implementation manner of the communication device may refer to the behavioral function in the communication method provided by any one of the possible designs of the thirteenth aspect or the thirteenth aspect, and any one of the possible design methods of the thirteenth aspect or the thirteenth aspect may be correspondingly implemented by that the communication device includes the obtaining unit and the sending unit.

In a fifteenth aspect, a communication device is provided, comprising: a processor and a memory; the memory is used for storing computer-executable instructions, and when the communication device is operated, the processor executes the computer-executable instructions stored in the memory, so that the communication device executes the communication method according to any one of the above-mentioned thirteenth aspect and thirteenth possible designs.

In a sixteenth aspect, there is provided a computer-readable storage medium having stored therein instructions, which, when run on a computer, cause the computer to perform the communication method of the thirteenth aspect or any one of the possible designs of the above aspects.

A seventeenth aspect provides a computer program product comprising instructions which, when run on a computer, causes the computer to perform the communication method of the thirteenth aspect or any one of the possible designs of the aspects.

In an eighteenth aspect, a chip system is provided, where the chip system includes a processor and a communication interface, and is configured to support a communication device to implement the functions in the foregoing aspects, for example, the processor determines to deactivate a multicast session corresponding to a multicast service, and sends eighth information indicating that the multicast session is deactivated to a first access and mobility management function network element or a second access and mobility management function network element, where the first access and mobility management function network element corresponds to one terminal in a multicast group corresponding to the multicast service, and the second access and mobility management function network element corresponds to the multicast group corresponding to the multicast service. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the communication device. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

For technical effects brought by any design manner of the fifteenth aspect to the eighteenth aspect, reference may be made to the technical effects brought by any possible design of the thirteenth aspect or the thirteenth aspect, and details are not repeated.

In a nineteenth aspect, there is also provided a communication method, including: the first terminal receives the paging message, determines that the PDU session associated with the multicast session is in a deactivated state, and sends a first message (e.g., a service request) to the access network device, where the first message is used to activate the PDU session associated with the multicast session.

Based on the method in the nineteenth aspect, when the first terminal receives the paging message, if it is determined that the PDU session associated with the multicast session is in a deactivated state, the first terminal sends a first message for activating the PDU session associated with the multicast session to the access network device, so as to activate the PDU session associated with the multicast session. So as to map/inject the data of the multicast service onto the PDU session subsequently under a certain application scenario (e.g. a handover scenario), thereby ensuring the normal transmission of the data of the multicast service.

In one possible design, the paging message includes identification information of the first terminal or identification information of the multicast group, i.e., paging can be initiated to a single terminal or group paging can be performed, and the paging method is flexible and diverse and has a wide application range.

In a twentieth aspect, the present application provides a communication device, which may be a first terminal or a chip or a system on a chip in the first terminal. The communication apparatus may implement the functions performed by the first terminal in the nineteenth aspect or the possible designs of the nineteenth aspect, and the functions may be implemented by hardware or by hardware executing corresponding software. The hardware or software comprises one or more modules corresponding to the functions. Such as: the communication apparatus may include: a receiving unit, a processing unit and a sending unit;

a receiving unit, configured to receive the paging message.

A processing unit for determining that a PDU session associated with the multicast session is in a deactivated state,

a sending unit, configured to send a first message (e.g., a service request) to the access network device, where the first message is used to activate a PDU session associated with a multicast session.

The specific implementation manner of the communication apparatus may refer to the behavior function of the first terminal in the communication method provided by any one of the possible designs of the nineteenth aspect or the nineteenth aspect, and any one of the possible designs of the nineteenth aspect or the nineteenth aspect may be correspondingly implemented by that the communication apparatus includes the obtaining unit and the sending unit.

In a twenty-first aspect, there is provided a communication apparatus comprising: a processor and a memory; the memory is configured to store computer-executable instructions, and when the communication apparatus is running, the processor executes the computer-executable instructions stored in the memory to enable the communication apparatus to perform the communication method according to any one of the possible designs of the nineteenth aspect or the nineteenth aspect.

In a twenty-second aspect, there is provided a computer-readable storage medium having stored therein instructions, which, when run on a computer, cause the computer to perform the communication method of the nineteenth aspect or any one of the possible designs of the above aspects.

A twenty-third aspect provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the communications method of the nineteenth aspect or any of the possible designs of the above aspects.

A twenty-fourth aspect provides a chip system, which includes a processor and a communication interface, and is configured to enable a communication apparatus to implement the functions recited in the foregoing aspects, for example, the processor receives a paging message through the communication interface, determines that a PDU session associated with a multicast session is in a deactivated state, and sends a first message (e.g., a service request) to an access network device, where the first message is used to activate the PDU session associated with the multicast session. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the communication device. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

For technical effects brought by any design manner in the twenty-first aspect to the twenty-fourth aspect, reference may be made to technical effects brought by any possible design manner in the nineteenth aspect or the nineteenth aspect, and details are not repeated.

A twenty-fifth aspect provides a communication system, which may include the communication device or chip system according to any one of the eighth to twelfth aspects, and the second session management function network element according to any one of the eighth to twelfth aspects; alternatively, the communication system comprises a communication device or chip system according to any of the fourteenth to eighteenth aspects, and the first access and mobility management function network element according to any of the eighth to twelfth aspects; alternatively, the communication system comprises a communication device or chip system according to any of the fourteenth to eighteenth aspects and the second access and mobility management function network element according to any of the eighth to twelfth aspects.

In a twenty-sixth aspect, an embodiment of the present application further provides a communication method, where the method includes: the access network equipment multicasts the data of the service, and the access network equipment determines that the received data corresponds to the multicast service; and the access network equipment sends a paging message to the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service.

Based on the method in the twenty-sixth aspect, when the access network device determines that the data received from the user plane is data of a multicast service, the access network device is triggered to page a terminal in an RRC _ inactive state in a multicast group corresponding to the multicast service, so as to ensure that the terminal in the multicast group normally receives the data of the multicast service.

In one possible design, the determining, by the access network device, to activate the multicast service according to the data includes: the access network equipment determines that the data corresponds to the multicast service, determines that the multicast service is in a deactivated state, and determines to activate the multicast service.

In a possible design, the determining, by the access network device, that the data corresponds to the multicast service includes: and the access network equipment determines the multicast service corresponding to the data according to the information of the tunnel for transmitting the data and/or the corresponding relation between the information of the tunnel and the identification information of the multicast service. Based on the possible design, the tunnel for transmitting the data of the multicast service and the multicast service can be associated, so that the data received from the tunnel is determined to be the data of the multicast service according to the corresponding relation, and the system design is simplified.

In one possible design, an access network device sends a paging message to a terminal in an RRC _ inactive state in a multicast group corresponding to a multicast service, where the paging message includes: the access network equipment determines the terminals in the RRC _ inactive state in the terminals of the multicast group and sends a paging message to the terminals in the RRC _ inactive state.

Assuming that the terminals in the RRC _ inactive state include a first terminal and a second terminal; the sending, by the access network device, a paging message to a terminal in an RRC _ inactive state in a multicast group corresponding to the multicast service includes: the access network equipment sends a first paging message at the RNA of a first terminal, wherein the first paging message comprises the identification information of the first terminal, and sends a second paging message at the RNA of a second terminal, wherein the second paging message comprises the identification information of the second terminal; or the access network equipment sends a paging message in the RNA of the first terminal and the RNA of the second terminal, wherein the paging message comprises the identification information of the multicast service.

The method for sending the paging message in the RNA of the first terminal and the RNA of the second terminal by the access network equipment comprises the following steps: during one paging cycle, the access network device sends a paging message in the overlapping area of the first terminal's RNA and the second terminal's RNA.

Based on the possible design, the paging message can be sent with per UE as granularity, or with multiple UEs as granularity, providing multiple ways to page the terminals in the multicast group, and flexibly and efficiently paging the terminals in RRC _ inactive. Meanwhile, when the paging messages are sent by taking a plurality of UE as granularity, the paging messages are sent only once for the repeated area, and the signaling overhead is reduced.

In a twenty-seventh aspect, an embodiment of the present application further provides a communication method, where the method includes: the access network equipment receives information which is from an access and mobility management network element and used for indicating the multicast session corresponding to the deactivated multicast service; and the access network equipment sends a paging message to the terminals in the RRC _ inactive state in the multicast group corresponding to the multicast service according to the information.

Based on the method in the twenty-seventh aspect, the access network device may learn from the core network to deactivate the multicast session, and then trigger the access network device to page the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service, so as to ensure that the terminal in the multicast group normally receives data of the multicast service.

In one possible design, an access network device sends a paging message to a terminal in a radio resource control _ inactive RRC _ inactive state in a multicast group corresponding to a multicast service, where the method includes: and the access network equipment determines the terminals in the RRC _ inactive state in the terminals of the multicast group and sends a paging message to the terminals in the RRC _ inactive state.

In a twenty-eighth aspect, an embodiment of the present application further provides a communication system, where the communication system may include: the session management function network element is used for determining the multicast session corresponding to the deactivated multicast service and sending information for indicating the deactivation of the multicast session to the access and mobility management network element; the access and mobility management network element is used for receiving the information and sending the information to the access network equipment; and the access network equipment is used for receiving the information and sending a paging message to a terminal in a radio resource control _ inactive RRC _ inactive state in a multicast group corresponding to the multicast service according to the information.

Drawings

FIG. 1a is a diagram of a PDU session;

FIG. 1b is a schematic diagram of a multicast session;

FIG. 1c is a diagram illustrating the association between a PDU session and a multicast session;

FIG. 2 is a block diagram of a communication system;

FIG. 3a is a schematic diagram of a 5G communication system;

FIG. 3b is a schematic diagram of another 5G communication architecture;

fig. 3c is a schematic diagram of a multicast/broadcast service transmission method according to an embodiment of the present application;

fig. 4 is a schematic diagram illustrating a communication device 400 according to an embodiment of the present disclosure;

fig. 5 is a flowchart of a communication method according to an embodiment of the present application;

fig. 6 is a flowchart of a communication method according to an embodiment of the present application;

fig. 7 is a flowchart of another communication method provided in the embodiment of the present application;

fig. 8 is a flowchart of another communication method provided in an embodiment of the present application;

fig. 9 is a flowchart of another communication method provided in the embodiment of the present application;

fig. 10 is a flowchart of another communication method provided in the embodiment of the present application;

fig. 11 is a flowchart of another communication method provided in the embodiment of the present application;

fig. 12 is a flowchart of another communication method according to an embodiment of the present application;

fig. 13 is a flowchart of another communication method provided in the embodiment of the present application;

Fig. 14a is a flowchart of another communication method according to an embodiment of the present application;

fig. 14b is a flowchart of another communication method according to an embodiment of the present application;

fig. 14c is a flowchart of another communication method according to an embodiment of the present application;

fig. 15 is a schematic diagram illustrating a communication device 150 according to an embodiment of the present disclosure;

fig. 16 is a schematic diagram illustrating a communication device 160 according to an embodiment of the present disclosure;

fig. 17 is a schematic diagram illustrating a communication device 170 according to an embodiment of the present disclosure;

fig. 18 is a schematic diagram illustrating a communication device 180 according to an embodiment of the present disclosure;

fig. 19 is a schematic composition diagram of a communication system according to an embodiment of the present application.

Detailed Description

Prior to the description of the embodiments of the present application, terms of the related art to which the embodiments of the present application relate will be explained. It should be noted that the explanation is for the purpose of making the embodiments of the present application easier to understand, and should not be construed as limiting the scope of the claims of the embodiments of the present application.

A Protocol Data Unit (PDU) session is a transmission path (or called a transmission tunnel) for transmitting service data (such as data of a multicast service or data of a unicast service) to a terminal in a unicast manner, and a PDU session may include an air interface resource allocated by a data network to a core network device (such as a user plane functional network element), to a unicast transmission path, and to an access network device for transmitting service data to a specific terminal. After the access network device receives the service data transmitted in the PDU session, the access network device may send the service data to a terminal corresponding to the PDU session through a Point To Point (PTP) unicast manner on an air interface. One PDU session is oriented to one terminal, the PDU session is at User Equipment (UE) level, and one terminal corresponds to one or more PDU sessions.

For example, as shown in fig. 1a, each of 3 terminals (such as terminal 1, terminal 2 and terminal 3) corresponds to one PDU session. Three different service data sent by a service provider (e.g., application server/service provider (AS/CP)) may be sent to a terminal through a PDU session corresponding to each terminal, for example, the PDU session in fig. 1a corresponds to 3 terminals from the AS/CP to the terminal through a user plane functional network element and an access network device. After receiving the service data transmitted in the 3 PDU sessions, the access network device may send the service data to the terminal 1, the terminal 2, and the terminal 3 in a unicast manner, that is, a PTP manner, respectively. In fig. 1a, the service data of each terminal may be different (for example, the target addresses are Internet Protocol (IP) addresses of the terminals respectively), and the service data of each terminal may be sent to the corresponding terminal through a PDU session corresponding to each terminal.

A multicast (multicast) session may provide a transmission service for one multicast service, where the multicast session may be a transmission path for transmitting data of the multicast service to a plurality of terminals in a multicast group in a multicast manner, and the plurality of terminals joining the multicast group may share the multicast session. The multicast session may include a transmission path from the data network to a core network device (e.g., a user plane function network element), a multicast session tunnel from the user plane function network element to a device for transmitting data of the multicast service, and an air interface resource allocated by the access network device for sending data of the multicast service. After the access network device receives the service data transmitted in the multicast session, on an air interface, the access network device may send a service data to a plurality of terminals joining a multicast group corresponding to the multicast session in a point-to-multipoint (PTM) multicast manner, and bear the service data on air interface resources allocated by the access network device for the plurality of terminals to send the service data to the plurality of terminals. One multicast session faces a plurality of terminals in one multicast group, one multicast group corresponds to one or a plurality of multicast sessions, the multicast sessions are service levels, and one type of multicast service can correspond to one or a plurality of multicast sessions.

For example, AS shown in fig. 1b, data of the multicast service may be transmitted from the AS/CP to the terminal 1, the terminal 2, and the terminal 3 through the multicast session. The transmission path from the AS/CP to the access network device may include a transmission path between the AS/CP and the user plane functional network element, and a transmission path between the user plane functional network element and the access network device (e.g., a multicast session), where the multicast session is shared by the terminal 1, the terminal 2, and the terminal 3. On the air interface, the access network device sends the data of the multicast service to the terminal 1, the terminal 2 and the terminal 3, that is, only one copy of the data of the multicast service needs to be sent, and 3 terminals can receive the data.

It should be noted that "multicast" in the present application is a broad concept, and may include multicast (multicast) or broadcast (broadcast), that is, the embodiments of the present application may be applied to both multicast service transmission and broadcast service transmission. The "multicast" referred to in this application may be replaced by "multicast or broadcast". In addition, the multicast session (multicast session) in the present application may be replaced by a multicast service session (multicast service session) or a multicast broadcast service session (MBS session), which is not limited.

In one possible implementation, a terminal may join a multicast group corresponding to a multicast session through any one PDU session of one or more PDU sessions established by the terminal, for example, the terminal joins the multicast group through a control plane message (e.g., a PDU session establishment/modification request) of the PDU session, where the control plane message carries identification information of a multicast service and indication information of joining the multicast group, and the like; for another example, the terminal joins the multicast group through a user plane notification message of the PDU session (e.g., internet group management protocol/multicast listener discovery protocol (IGMP/MLD join)), where the user plane notification message carries, for example, identification information of the multicast service and indication information of joining the multicast group.

It should be understood that, the adding of the multicast group described in this application may also be described as adding a multicast session, or adding a multicast service, or adding a Multicast Broadcast Service (MBS), or adding a multicast session corresponding to a multicast service (multicast session) or adding a multicast broadcast service session corresponding to a multicast service (MBS session), etc., without limitation.

In this embodiment of the present application, if one PDU session is used for a terminal to join a multicast group corresponding to a multicast session, the PDU session may be referred to as a PDU session associated with the multicast session. Further, after the terminal joins the multicast group corresponding to the multicast session through the PDU session, the association relationship between the PDU session and the multicast session may be recorded on the terminal, the access network device, and the core network device (e.g., an access and mobility management function network element, a session management function network element, a network storage function network element (e.g., a Unified Database (UDR), etc.). Illustratively, the association relationship between the PDU session and the multicast session may be recorded in one or more of the following manners: 1), a session management context (SM context) of the PDU session, and related information (e.g., identification information of the multicast service, etc.) of the multicast service is stored in the SM context); 2) The ID of the SM context of the PDU session points to the multicast service, and if the ID of the SM context of the PDU session is stored in correspondence with the identification information of the multicast service; 3) The context corresponding to the multicast service (e.g., a multicast/broadcast service session context (MBS session context), a multicast/broadcast group context (MBS group context), a multicast/broadcast service context (MBS service context), a multicast/broadcast context (MBS context)) stores therein information of the terminal (e.g., identification information of the terminal) and/or information of a PDU session associated with the multicast session (e.g., identification information of the PDU session).

In this embodiment, the identification information of the terminal may be used to identify the terminal, and the identification information of the terminal may include, but is not limited to, a hidden user identifier (SUCI) of the terminal, a permanent user identifier (SUPI) of the terminal, or a general public user identifier (GPSI) of the terminal.

In the embodiment of the application, the identification information of the PDU session can identify the PDU session. The identification information of the PDU session may include, but is not limited to, an ID of the PDU session or a session management context identification (SM context ID) of the PDU session, etc.

It should be noted that, in this embodiment of the present application, adding to a multicast session through a PDU session may be alternatively described as adding to a multicast/broadcast service (MBS) through a PDU session, and associating a PDU session with a multicast session may be alternatively described as associating a PDU session with a multicast/broadcast service, which is not limited.

For example, fig. 1c is a schematic diagram of association between a PDU session of a User Equipment (UE) and a multicast session, where UE1 has 3 PDU sessions, and the identities (PDU session IDs) of the 3 PDU sessions are 1, 3, and 5, respectively, where it is assumed that a PDU session with an ID of 1 and a PDU session with an ID of 3 are served by a Session Management Function (SMF) 1, and a PDU session with an ID of 6 is served by an SMF 2. UE1 joins 3 multicast services (or referred to as multicast sessions) through the PDU session with ID 1, MBS IDs (1, 3, 5), that is, the PDU session with PDU session ID 1 associates 3 MBS, and the MBS IDs are 1, 3, 5, respectively. Similarly, the PDU session with ID 3 is associated with 2 MBS, and the MBS IDs are 2 and 4 respectively; the PDU session with ID 6 associates 3 MBS, whose IDs are 6, 7, and 8, respectively. The MB-SMF in fig. 1c is a multicast/broadcast session management function network element (MBs-session management function) responsible for establishing and managing multicast sessions, etc. The relation shown in fig. 1c may be stored in the SM context of the PDU session or in the context related to the multicast service, or in the UDR, which is not limited herein.

As can be seen from the above, there is an association relationship between the PDU session for the terminal to join the multicast session and the multicast session for the terminal to join. In the communication process, if the PDU session is deactivated without considering the association relationship between the PDU session and the multicast session, the switching of the data of the multicast service from the multicast session to the PDU session associated with the multicast session may fail, and the transmission continuity of the data of the multicast service may be affected. For another example, in order to ensure service continuity assurance (e.g., service continuity of multicast session transmission), to prevent that when a terminal device performs handover, if an associated PDU session is not activated, the multicast service continuity cannot be ensured. Specifically, during switching, the data of the multicast service transmitted by the multicast session may be injected into the PDU session associated with the multicast session, and then switching is performed, so that the continuity of the multicast service may be ensured. If the associated PDU session is still in a deactivated state when the switching occurs, the data of the multicast service cannot be mapped/injected into the PDU session, and the normal transmission of the data of the multicast service during the switching is ensured.

To solve the problem, an embodiment of the present application provides a communication method, which may include: when the PDU session of the first terminal is deactivated, determining whether the PDU session to be deactivated is associated with a multicast session corresponding to the multicast service and determining whether the multicast session is in an activated state, namely, determining whether the multicast session associated with the PDU session to be deactivated is in an activated state, and if the PDU session is associated with the multicast session and the multicast session is in the activated state, keeping the PDU session in the activated state; if the multicast session is in a deactivated state, the PDU session may be deactivated. Further optionally, when second information for activating the multicast session is received (e.g., multicast/broadcast service session start/start (MBS session start), multicast broadcast service session activation (MBS session activation), or multicast session activation (multicast session activation)), the first session management function network element corresponding to the first terminal may determine whether the PDU session associated with the multicast session is in an activated state, and if the PDU session associated with the multicast session is in a deactivated state, the first session management function network element needs to activate the PDU session associated with the multicast session, so as to ensure that data of the multicast service is normally transmitted when the multicast service is switched from the multicast session to the PDU session. Specifically, this implementation is described with reference to the embodiments corresponding to fig. 5 to 7.

Alternatively, an embodiment of the present application provides another communication method, where the method may include: when the first session management function network element corresponding to the first terminal receives second information (e.g., multicast/broadcast service session start, multicast broadcast service session activation, or Multicast session activation) indicating activation of the Multicast session, the first session management function network element notifies the access network device to add the first terminal to a Multicast group corresponding to the Multicast session. Further optionally, if the PDU session associated with the multicast session is in a deactivated state, the PDU session associated with the multicast session is activated, so as to ensure that data of the multicast service is normally transmitted when the multicast service is switched from the multicast session to the PDU session, or ensure continuity of switching the multicast service at the first terminal. Specifically, this implementation is described with reference to the corresponding embodiments in fig. 8 to 14 a.

It should be noted that, in this embodiment of the present application, a multicast session associated with a PDU session may include one or more multicast sessions, and that the multicast session in an active state in this embodiment of the present application means that at least one multicast session in the multicast session associated with the PDU session is in an active state.

The technical solution in the embodiments of the present application is described below with reference to the drawings in the embodiments of the present application.

The communication method provided in the embodiment of the present application may be applied to the communication system shown in fig. 2, and as shown in fig. 2, the communication system may include a plurality of terminals (e.g., a first terminal, etc.), an access network device, and a first session management function network element. Further, the communication system shown in fig. 2 may further include an access and mobility management function network element, a first user plane function network element, a second session management function network element, a second user plane function network element, a policy control network element, a network storage network element, a Data Network (DN), where the DN may include an Application Server (AS), and the like. The access and mobility management function network element, the first user plane function network element, the second session management function network element, the second user plane function network element and the DN are optional network elements in the application.

A plurality of terminals may form a multicast group, and a plurality of terminals may receive the same data, that is, the data of the multicast service at the same time. The first user plane functional network element may be configured to transmit unicast data (unicast data) or data of a multicast service, the second user plane functional network element may be configured to transmit data of a multicast service (multicast data), the unicast data may be data sent to a specific terminal or user, and the data of a multicast service may be data sent to a multicast group. The first session management function network element may be a session management function network element that manages PDUs, and the second session management function network element may be a session management function network element that manages multicast services. The network elements or devices involved in the architecture shown in fig. 2 are described below.

A terminal may be referred to as a terminal equipment (terminal equipment) or a User Equipment (UE) or a Mobile Station (MS) or a Mobile Terminal (MT), etc. Specifically, the terminal in fig. 2 may be a mobile phone (mobile phone), a tablet computer, or a computer with a wireless transceiving function, and may also be a Virtual Reality (VR) terminal, an Augmented Reality (AR) terminal, a wireless terminal in industrial control, a wireless terminal in unmanned driving, a wireless terminal in telemedicine, a wireless terminal in a smart grid, a wireless terminal in a smart city (smart city), a smart home, a vehicle-mounted terminal, and the like.

The access network equipment is mainly used for realizing the functions of physical layer function, resource scheduling and management, terminal access control, mobility management and the like. The access network device may be a device supporting wired access or a device supporting wireless access. Illustratively, the access network device may be AN Access Network (AN)/Radio Access Network (RAN), and may be composed of a plurality of 5G-AN/5G-RAN nodes. The 5G-AN/5G-RAN node may be: an Access Point (AP), a base station (nodeB, NB), an enhanced base station (eNB), a next generation base station (NR nodeB, gNB), a Transmission Reception Point (TRP), a Transmission Point (TP), or some other access node, etc.

The access and mobility management functional network element is mainly responsible for the operations of access authentication, mobility management, signaling interaction among the functional network elements, and the like of the terminal, such as: and managing the registration state of the user, the connection state of the user, the user registration and network access, the tracking area updating, the cell switching user authentication, the key safety and the like.

A session management function network element, which is mainly used for implementing a user plane transmission logic channel, such as: a session management function such as establishment, release, and modification of a Packet Data Unit (PDU) session or a multicast session.

The user plane functional network element may be used as an anchor point on a user plane transmission logical channel, and is used to complete functions such as routing forwarding of user plane data, for example: and a channel (namely a user plane transmission logic channel) is established between the network node and the terminal, and the channel forwards a data packet between the terminal and the DN and is responsible for filtering data messages of the terminal, forwarding data, controlling the rate and generating charging information.

The policy control network element may be configured to provide a policy to an access and mobility management function network element and a session management function network element, where the policy control network element includes: quality of service (quality of service) policies, slice selection policies, and the like.

Network storage network elements may be used to store user data, such as: subscription information, authentication or authorization data, etc. of the user. Specifically, the network storage network element may be a unified data management network element (UDM), a network storage function (NRF), a Unified Data Repository (UDR), or the like.

DN, operator network that may provide data transmission services to users, such as: an operator network or the like that provides IP Multimedia Services (IMS) to users. An application server may be deployed in the DN and may provide data transmission services to users.

It should be noted that fig. 2 is only an exemplary architecture diagram, and besides the functional units shown in fig. 2, the system may also include other functional network elements, such as: an operation and management (O & M) network element, and the like, which are not limited in this embodiment of the present application. In addition, the names of the devices in fig. 2 are not limited, and besides the names shown in fig. 2, the devices may also be named by other names, such as network element names with the same or similar functions instead of the names, without limitation.

The system shown in fig. 2 may be a third generation partnership project (3 rd generation partnership project,3 GPP) communication system, such as a 4th generation (4 g) communication system, a Long Term Evolution (LTE) system, a fifth generation (5g) communication system, a New Radio (NR) system, a next generation communication system, or a non-3 GPP communication system, which is not limited.

Taking the communication system shown in fig. 2 as the 5G communication system shown in fig. 3a as an example, as shown in fig. 3a, a network element or an entity corresponding to the second session management function network element may be a multicast/broadcast session management function (MB-SMF) in the 5G communication system, and a network element or an entity corresponding to the second user plane function network element may be a user plane function (MB-UPF) in the 5G communication system. The network element or entity corresponding to the access network device may be a Radio Access Network (RAN) in the 5G communication system, the network element or entity corresponding to the access and mobility management function network element may be an access and mobility management function (AMF) in the 5G communication system, and the policy control function may be a Policy Control Function (PCF) in the 5G communication system.

It should be noted that, in the present application, the SMF and the MB-SMF may be combined, or may be separately deployed, without limitation. In the present application, the UPF and the MB-UPF may be combined, or may be deployed independently, without limitation.

Taking the communication system shown in fig. 2 as the 5G communication system shown in fig. 3b as an example, unlike the system shown in fig. 3a, the system shown in fig. 3b may further include a multicast/broadcast service transport function (MBSTF) and a multicast/broadcast service function (MBSF). The MBSTF may have a function of a UPF for transmitting multicast service data. The MBSF may have the function of MB-SMF, such as establishing/managing a multicast session corresponding to a multicast service; the MBSF can also support the MBMS intercommunication with LTE and the like.

In the embodiment of the application, under the condition that the access network device does not support the multicast function, multicast service data can be transmitted between the access network device and a user plane network element in a 5G core network single multicast/broadcast service flow transmission mode. Under the condition that the access network equipment supports the multicast function, the multicast/broadcast service data can be transmitted in a 5G core network shared multicast/broadcast service traffic transmission (5 GC shared MBS traffic transmission) mode. For example, as shown in fig. 3c, in the 5GC shared MBS traffic delivery mode, the multicast/broadcast service data directly reaches the RAN through the MB-UPF and the N3 tunnel between the MB-UPF and the RAN, and the RAN may send the data to the terminal joining the multicast service in a point-to-point (PTP) or point-to-multipoint (PTM) mode. The 5G core network is in a single multicast/broadcast service flow transmission mode, multicast/broadcast service data reach a UPF through an MB-UPF, then reach a RAN through an N3 tunnel (such as PDU session of a terminal) between the UPF and the RAN, and the RAN sends the data to the terminal point by point.

The access network device does not support the multicast function, which may be understood as that the access network device does not support the multicast/broadcast service data transmission in a 5G core network shared multicast/broadcast service traffic transmission (5 GC shared MBS traffic transmission) manner, that is, only supports the 5G core network single multicast/broadcast service traffic transmission (5 GC industrial MBS traffic transmission) manner to transmit the multicast/broadcast service data, that is, the multicast/broadcast service data is transmitted to the terminal through the associated PDU session of the terminal added with the multicast service.

It should be understood that after the multicast/broadcast service data arrives at an access network device (e.g., RAN), the multicast/broadcast service data is processed by a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Media Access Control (MAC) layer, and a Physical (PHY) layer of the RAN, and is transmitted to each terminal receiving the multicast/broadcast service data.

Optionally, the session management function network element, the access network device, and the access and mobility management function network element in this embodiment may also be referred to as a communication device, which may be a general device or a special device, which is not specifically limited in this embodiment of the present application. Optionally, the functions related to the session management function network element, the user plane function network element, the access network device, and the access and mobility management function network element in this embodiment may be implemented by one device, may also be implemented by multiple devices together, and may also be implemented by one or more function modules in one device, which is not specifically limited in this embodiment of the present application. It will be appreciated that the above functions may be network elements in a hardware device, or may be software functions running on dedicated hardware, or a combination of hardware and software, or virtualized functions instantiated on a platform (e.g., a cloud platform).

In a specific implementation, each device shown in fig. 2, such as the first session management function network element, the access network device, the access and mobility management function network element, and the like, may adopt the composition structure shown in fig. 4, or include the components shown in fig. 4. Fig. 4 is a schematic diagram illustrating a communication device 400 according to an embodiment of the present disclosure, where the communication device 400 may include a processor 401 and a memory 404. Further, the communication device 400 may further include a communication line 402 and a communication interface 403. The processor 401, the memory 404 and the communication interface 403 may be connected by a communication line 402.

The processor 401 may be a Central Processing Unit (CPU), a general purpose processor, a Network Processor (NP), a Digital Signal Processor (DSP), a microprocessor, a microcontroller, a Programmable Logic Device (PLD), or any combination thereof. The processor 401 may also be other means with processing functionality such as, without limitation, a circuit, a device, or a software module.

A communication line 402 for transmitting information between the respective components included in the communication apparatus 400.

A communication interface 403 for communicating with other devices or other communication networks. The other communication network may be an ethernet, a Radio Access Network (RAN), a Wireless Local Area Network (WLAN), or the like. The communication interface 403 may be a module, a circuit, a transceiver, or any device capable of enabling communication.

A memory 404 for storing instructions. Wherein the instructions may be a computer program.

The memory 404 may be a read-only memory (ROM) or other types of static storage devices that can store static information and/or instructions, a Random Access Memory (RAM) or other types of dynamic storage devices that can store information and/or instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compact disc, laser disc, optical disc, digital versatile disc, blu-ray disc), a magnetic disc storage medium, other magnetic storage devices, and is not limited.

It is to be noted that the memory 404 may exist independently from the processor 401 or may be integrated with the processor 401. The memory 404 may be used for storing instructions or program code or some data or the like. The memory 404 may be located within the communication device 400 or may be located outside the communication device 400, without limitation.

The processor 401 is configured to execute the instructions stored in the memory 404 to implement the communication method provided by the following embodiments of the present application. For example, when the communication apparatus 400 is a first session management function network element or a chip or a system on chip in the first session management function network element, the processor 401 executes instructions stored in the memory 404 to implement the steps performed by the first session management function network element in the following embodiments of the present application. For another example, when the communication apparatus 400 is an access network device or a chip or a system on chip in the access network device, the processor 401 may execute instructions stored in the memory 404 to implement the steps performed by the access network device in the following embodiments of the present application.

In one example, processor 401 may include one or more CPUs, such as CPU0 and CPU1 in fig. 4.

As an alternative implementation, the communication device 400 includes multiple processors, for example, the processor 407 may be included in addition to the processor 401 in fig. 4.

As an alternative implementation, the communication apparatus 400 further includes an output device 405 and an input device 406. Illustratively, the input device 406 is a keyboard, mouse, microphone, or joystick, among other devices, and the output device 405 is a display screen, speaker (spaker), among other devices.

It should be noted that the communication apparatus 400 may be a desktop computer, a portable computer, a network server, a mobile phone, a tablet computer, a wireless terminal, an embedded device, a chip system, or a device with a similar structure as that in fig. 4. Further, the constituent structure shown in fig. 4 does not constitute a limitation of the communication apparatus, and the communication apparatus may include more or less components than those shown in fig. 4, or combine some components, or a different arrangement of components, in addition to the components shown in fig. 4.

In the embodiment of the present application, the chip system may be formed by a chip, and may also include a chip and other discrete devices.

In addition, acts, terms, and the like referred to between the embodiments of the present application may be mutually referenced and are not limited. In the embodiment of the present application, the name of the message exchanged between the devices or the name of the parameter in the message, etc. are only an example, and other names may also be used in the specific implementation, which is not limited.

The following describes a communication method provided in the embodiment of the present application, taking the architecture shown in fig. 2 as an example. Each network element in the following embodiments may have the components shown in fig. 4, which are not described in detail. It should be noted that, in the embodiment of the present application, a name of a message or a name of a parameter in a message that is interacted between devices is only an example, and other names may also be used in specific implementation. For example, the determination in the embodiment of the present application may also be understood as creating (create) or generating (generate), the "including" in the embodiment of the present application may also be understood as "carrying" and the like, the "indicating (indication)" in the embodiment of the present application may also be understood as "triggering (trigger)" or "notifying (notify)" or "request)" and the like, and this is not specifically limited in the embodiment of the present application.

Fig. 5 is a flowchart of a communication method according to an embodiment of the present application, where the method may be executed by a first session management function network element or by an access network device, where the first session management function network element may be a session management function network element corresponding to a PDU session of a first terminal, the first session management function network element manages the PDU session of the first terminal, and the access network device may be an access network device corresponding to the PDU session of the first terminal. As shown in fig. 5, the method may include:

s501: and determining whether the PDU session to be deactivated is associated with the multicast session corresponding to the multicast service.

The PDU session may be a PDU session of the first terminal, and the first terminal may be any one of the terminals in fig. 2. It should be noted that, in the present application, the PDU session to be deactivated may be the last PDU session in the activated state/not released corresponding to the first terminal, or may be any PDU session in a plurality of PDU sessions in the activated state/not released corresponding to the first terminal, which is not limited.

In this application, a session management function network element corresponding to a PDU session is a first session management function network element, a user plane function network element corresponding to the PDU session is a first user plane function network element, and the first user plane function network element is an anchor point (PDU session anchor UPF, PSA) of the PDU session. And the session management function network element corresponding to the multicast session is a second session management function network element, and the user plane function network element corresponding to the multicast session is a second user plane function network element.

In the case where the method shown in fig. 5 is executed by the access network device, if the access network device does not receive data transmitted on the PDU session for a long time, it is determined that the PDU session is to be deactivated, or if the access network device determines that the first terminal does not receive data transmitted on the PDU session any longer, if the first terminal moves out of the service area, it is determined that the PDU session is to be deactivated. Or, in a scenario that the first session management function network element receives information that the PDU session transmission data is not detected for a period of time from the first user plane function network element, after determining that the PDU session is to be deactivated, the first session management function network element may send information for indicating or notifying that the PDU session is to be deactivated to the access network device, for example, the first session management function network element sends fifth information to the access network device through the first access and mobility management function network element, the fifth information may be used for indicating that the PDU session is to be deactivated, the access network device receives the fifth information indicating that the PDU session is to be deactivated from the first session management function network element, and determines that the PDU session is to be deactivated according to the fifth information.

The first access and mobility management functional network element corresponds to a first terminal, and is an access and mobility management functional network element of a non-access stratum (NAS) signaling service of the first terminal, and the second access and mobility management functional network element corresponds to a multicast group corresponding to a multicast session.

In the case that the method shown in fig. 5 is executed by the first session management function network element, if the first session management function network element receives information that PDU session transmission data is not detected for a period of time from the first user plane function network element, it determines that a PDU session is to be deactivated; or the first session management function network element receives information from the instruction or notification to deactivate the PDU session, and determines to-be-deactivated PDU session; or, after receiving the message, sent by the first access and mobility management function network element, for indicating that the first terminal moves out of the service area, the first session management function network element determines to deactivate the PDU session of the first terminal. Or, the first session management functional network element receives indication information that the PDU session transmission data is not detected for a period of time from the first user plane network element, and the first session management functional network element determines to deactivate the PDU session according to the indication information that the PDU session transmission data is not detected, which is sent by the first user plane network element.

Further, after determining that the PDU session is to be deactivated, the first session management function network element may send fifth information for indicating or notifying that the PDU session is to be deactivated to the access network device, for example, the first session management function network element sends the fifth information to the access network device through the first access and mobility management function network element, and the fifth information may be used for indicating that the PDU session is to be deactivated, so that the access network device receives the fifth information indicating that the PDU session is to be deactivated from the first session management function network element, and determines that the PDU session is to be deactivated according to the fifth information.

Further, if the method shown in fig. 5 is executed by the access network device, (for example, if the PDU session to be deactivated is the last PDU session of the first terminal, the access network device is triggered to initiate AN access network release (AN release) procedure, and before initiating the AN release procedure, the access network device determines whether the PDU session to be deactivated is associated with a multicast session corresponding to the multicast service, that is, whether a multicast session associated with the PDU session to be deactivated exists, and determines whether to initiate AN access network release (AN release) procedure according to a determination result and a state of the multicast session.

For example, in the present application, after determining that a PDU session is to be deactivated, a first session management function network element or an access network device may determine whether the PDU session to be deactivated is associated with a multicast session corresponding to a multicast service according to an association relationship between the PDU session and the multicast session recorded by a local or other network element. Specifically, the method includes the following three different determination manners (1) to (3), and it should be noted that the manner of determining whether the PDU session to be deactivated is associated with the multicast session corresponding to the multicast service is not limited to any one of the following three manners, and may also be another manner.

(1) And under the condition that the association relationship between the PDU session and the multicast session is recorded by adopting the above mode 1), searching for the SM Context of the PDU session by using the identification information of the PDU session as an index, determining whether there is related information of the multicast service in the SM Context of the PDU session, for example, whether there is identification information (such as MBS session ID, TMGI, multicast session ID, IP multicast address, and the like) corresponding to the multicast service in the SM Context of the PDU session, if there is related information of the multicast service, determining that the PDU session to be deactivated is associated with the multicast session corresponding to the multicast service, otherwise, determining that the PDU session to be deactivated is not associated with the multicast session.

(2) And under the condition of recording the association relationship between the PDU Session and the multicast Session by adopting the mode 2), searching whether the identification information (such as MBS Session ID, TMGI, multicast Session ID or TMGI and the like) of the multicast service corresponding to the ID of the SM context exists locally by taking the ID of the SM context of the PDU Session as an index, if so, determining that the PDU Session to be deactivated is associated with the multicast Session, otherwise, determining that the PDU Session to be activated is not associated with the multicast Session.

(3) And under the condition that the association relationship between the PDU session and the multicast session is recorded by adopting the mode 3), checking whether the locally stored Context related to the multicast session has the identification information of the first terminal and/or the identification information (such as SM Context) of the PDU session of the first terminal, if so, determining that the PDU session to be deactivated is associated with the multicast session, otherwise, determining that the PDU session to be activated is not associated with the multicast session.

In this application, the context related to the multicast session may be referred to as a context of a multicast session, a multicast/broadcast service context (multicast/broadcast service context), a multicast/broadcast group context (multicast/broadcast group context), a multicast/broadcast service session context (MBS session context), a multicast/broadcast service context (multicast/broadcast service context), a multicast session context (multicast session context), a multicast group context (multicast group context), or a multicast service context (multicast service context), without limitation.

In this embodiment of the present application, the identification information of the PDU session may be used to uniquely identify the PDU session, and the identification information of the PDU session may include one or more of an ID of the PDU session and an ID of an SM context of the PDU session.

In an embodiment of the present invention, the identification information of the multicast service may be used to uniquely identify the multicast service, the identification information of the multicast service may include identification information of a multicast session, identification information of the multicast service, context information of the multicast session, address information of the multicast service, identification information of a PDU session associated with the multicast session, a Service Data Flow (SDF) identification rule of the multicast service, packet filtering (packet filter) information of data of the multicast service, identification information of a multicast group corresponding to the multicast service (e.g., temporary Mobile Group Identifier (TMGI) of the multicast group), multicast/broadcast service session ID (multicast/broadcast service session ID), multicast/broadcast service session ID (multicast session ID), multicast session ID (multicast session ID), application protocol (internet protocol, IP) of an application server (e.g., AF) providing data of the multicast service, a service identification (MBS) of the multicast service, a port number of the multicast service, and a port number of a packet filter, where the identification information of the multicast service is used for detecting a source address, a packet identifier (PDR packet) and a destination address, and a port number of the multicast service should be understood as one or more types of a packet filter.

The identification information of the first terminal may be used to uniquely identify the first terminal, and the identification information of the first terminal may be a subscription permanent identifier (SUPI) of the first terminal, an Internet Protocol (IP) address of the first terminal, a Media Access Control (MAC) address of the first terminal, or an International Mobile Subscriber Identity (IMSI) of the first terminal.

S502: it is determined whether the multicast session is active.

In the case where the method shown in fig. 5 is performed by the first session management function network element, the first session management function network element may determine whether the multicast session is in an active state by: the first session management function network element receives first information used for indicating the deactivation of the multicast session from the access network device or the second session management function network element, and the first session management function network element determines that the multicast session is in a deactivated state according to the first information. And the first session management function network element receives second information which is used for indicating the activation of the multicast session and is from the second session management function network element, and the first session management function network element determines that the multicast session is in an activated state according to the second information.

The second session management function network element corresponds to a multicast group, and the second session management function network element is a network element that manages a multicast session, and may be an MB-SMF shown in fig. 3 b. It should be understood that, the second session management function network element described in this application corresponds to a multicast group, which may be understood as that the second session management function network element has an ability to manage a multicast session corresponding to the multicast group, for example, the second session management function network element has an ability to establish, modify, or delete the multicast session of the multicast group. In addition, the second session management function network element corresponding to the multicast group may be alternatively described as the second session management function network element corresponding to a multicast session or a multicast service, and the like, which is not limited.

The first information may directly indicate (indication)/notify (notification) to deactivate the multicast session, for example, the first information may carry a cell/indicator (indication)/notify (notification), where the cell/indicator/notification explicitly indicates to deactivate the multicast session, or the first indication information may be multicast broadcast service session deactivation (MBS session deactivation) or multicast session deactivation (multicast session deactivation). In yet another example, the first information may indirectly indicate to deactivate the multicast session, for example, the first information may be used to indicate/notify that the multicast session is deactivated, for example, the first information may be multicast/broadcast service session stop (MBS session stop)/session stop (session stop), or the second user plane function network element does not detect data of the multicast service, or the first information may be used to indicate that the first terminal is in a Connection Management (CM) idle state, or the like, and the first session management function network element indirectly determines that the multicast session is in a deactivated state according to the first information. In another example, the first information may directly or indirectly indicate that the multicast session is in a deactivated state, and if the first session management function network element receives the first information, it is determined that the multicast session is in the deactivated state, otherwise, if the first information is not received, the default multicast session is still in the activated state.

The second information may directly indicate (indication)/notify (notification) to activate the multicast session, for example, the second information may carry a cell/indicator (indication)/notify (notification), where the cell/indicator/notification explicitly indicates to activate the multicast session, or the second information may be multicast/broadcast service session activation (MBS session activation) or multicast session activation (multicast session activation). In yet another example, the second information may indirectly indicate to activate the multicast session, for example, the second information may be used to indicate/notify that the multicast session is about to start/start, the second information is multicast/broadcast service session start (MBS session start)/session start (session start), or the second information is used to indicate that the second user plane function network element detects data of the multicast service, or the second information may be used to indicate that the first terminal is in a Connection Management (CM) connected state, or the like, and the first session management function network element indirectly determines that the multicast session is in an active state according to the second information.

In this embodiment, the multicast session may be alternatively described as a multicast/broadcast session, the state of the multicast session may be alternatively described as a state of the multicast/broadcast session, and the state of the multicast/broadcast session may include a deactivated state/an inactivated state (inactive or standby), an activated state (active), and a released state/a deleted state (released/deleted).

The state of the multicast/broadcast session being deactivated (inactive or MBS session deactivation) may refer to: the multicast/broadcast Session is deactivated when a service provider (content provider) starts/initiates/starts (inter) a multicast/broadcast Session stop (MBS Session stop or Session stop) or a multicast/broadcast service Session deactivation (MBS Session deactivation) or a multicast Session deactivation (multicast Session deactivation), information related to the multicast/broadcast Session is released at the terminal side and the access network device side during or after the execution of the multicast/broadcast Session is deactivated, and information related to the multicast/broadcast Session (e.g., MBS Session context or MB service context) is retained but set to a deactivated state at the first Session management function and/or the second Session management function network element. Specifically, the deactivation of the multicast/broadcast session may refer to that information related to the multicast/broadcast service (e.g., quality of service (QoS) information related to the multicast/broadcast service, etc.) is released in the terminal; the multicast/broadcast service related information is released at the access network device (e.g., a multicast/broadcast service related Context (e.g., multicast/broadcast Context (MB Context) or multicast/broadcast service session Context (MBs session Context) or multicast/broadcast group Context (MB group Context) or multicast/broadcast service Context (MBs Context)) is released); the method comprises the steps of receiving multicast/broadcast session information, releasing tunnel information related to the multicast/broadcast session, releasing air interface resources related to the multicast/broadcast session, releasing information related to the multicast/broadcast service in the Context of a terminal stored by an access network device, and the like, wherein the information related to the multicast/broadcast service is reserved between a first session management function network element and a second session management function network element but is set to be in a deactivated state (for example, the related information can be MBS session Context or MB service Context), or the information related to the multicast service is reserved at the first session management function network element but is set to be in a deactivated state but is released at the second session management function network element, or the related information related to the multicast service is released at the first session management function network element but is reserved at the second session management function but is set to be in a deactivated state, and the deactivated multicast session can be restarted/started/activated by a multicast session start flow (MBS session start) or a multicast session activation (multicast session activation).

The state of the multicast/broadcast service session (MBS session) being deactivated state (inactive or MBS session deactivation) may also refer to: the established multicast/broadcast session is in an inactive (inactive or MBS session deactivation) state. No data of the multicast/broadcast service is transmitted. End devices joining a multicast/broadcast session may be in a CM _ CONNECTED state or a CM _ IDLE state. The authenticated end device may be allowed to join the multicast/broadcast session. The activation operation (activation) may be triggered by an Application Function (AF)/Application Server (AS) request or may be triggered by the UPF detecting data arrival of the multicast/broadcast service. Activating a multicast/broadcast session requires paging back to CM _ CONNECTED state terminal devices that have joined the multicast/broadcast session and are in CM _ IDLE state. It should be noted that when the multicast/broadcast session is in the inactive state, the QoS information related to the multicast/broadcast service in the core network related element may be removed or retained (e.g., the QoS information related to the multicast/broadcast service in the MBS session context), for example, the QoS information related to the multicast/broadcast service is removed in both MB-SMF and SMF; or, qoS information related to the multicast/broadcast service is reserved in MB-SMF and removed in SMF; or, the QoS information related to the multicast/broadcast service is removed in the MB-SMF and is reserved in the SMF; or the multicast/broadcast service related QoS information is reserved at both MB-SMF and SMF. The QoS information related to the multicast/broadcast service may include, for example, a QoS Flow ID related to the multicast/broadcast service, a packet filter (e.g., a Service Data Flow (SDF) template of a service in a PCC rule for generating a Packet Detection Rule (PDR)), policy information related to the multicast/broadcast service, and the like. In addition, when the multicast/broadcast session is in a deactivated state, the MBS session context may be identified as an inactive state, or may not be identified. In addition, when the state of the multicast/broadcast session is inactive, the N3 tunnel associated with the multicast/broadcast service session is released or reserved. In addition, when the state of the multicast/broadcast session is an inactive state, the context related to the multicast/broadcast service can be removed/released/deleted from the access network device, and the context related to the multicast/broadcast service can also be retained in the access network device; or when the multicast/broadcast session is in a deactivated state, qoS information (e.g., qoS profile) related to multicast/broadcast related to the multicast/broadcast service is retained in the access network device, and for a terminal in a CM-CONNECTED state that joins the multicast/broadcast service, the access network device retains a context of the terminal, and the context of the terminal has a QoS profile corresponding to a unicast QoS flow mapped by the multicast/broadcast QoS flow, that is, when the multicast/broadcast session is deactivated, the QoS profile corresponding to the unicast QoS flow mapped by the multicast/broadcast QoS flow is retained in the access network device; or when the multicast/broadcast session is in a deactivated state, qoS information (e.g., qoS profile) related to the multicast/broadcast service is retained in the access network device.

The state of the multicast/broadcast session being active (or MBS session activation) may refer to: the method comprises the steps of starting a multicast/broadcast Session at a service provider (content provider), starting/initiating a multicast/broadcast Session at a start (Session start) or activating a multicast/broadcast service Session (MBS Session activation) or activating a multicast Session at a multicast Session activation (multicast Session activation), wherein information related to the multicast/broadcast Session is established at a terminal and an access network side during the execution process of activating the multicast/broadcast Session or after the execution of the multicast/broadcast Session is activated, and the information related to the multicast/broadcast Session is set to be in an active state at a first Session management function network element and/or a second Session management function network element. Specifically, the activation of the multicast/broadcast session may refer to: information related to the multicast/broadcast service (e.g., qoS information related to the multicast/broadcast service, etc.) is established/allocated in the terminal; the method comprises the steps of establishing information related to the multicast/broadcast service (e.g. a context related to the multicast/broadcast service (e.g. multicast/broadcast context (MB context)) or a multicast/broadcast service session context (MBs session context) or a multicast/broadcast group context (MB group context) or a multicast/broadcast service context (MBs context)) at an access network device, distributing tunnel information related to the multicast/broadcast session, distributing air interface resources related to the multicast/broadcast session, establishing information related to the multicast/broadcast service in the context of a terminal, etc., establishing a tunnel related to the multicast/broadcast session, setting the information related to the multicast/broadcast service in an active state (active) or the like at a first session management function network element and a second session management function network element, and deactivating the active multicast/broadcast session (MBs session) or deactivating the multicast/broadcast session (multicast session) flow.

The state of the multicast/broadcast session being active (or MBS session activation) may also refer to: the established multicast/broadcast session is in an active (active) state. The multicast/broadcast service data may be transmitted to terminals joining the multicast/broadcast group. The 5GC resources related to the multicast/broadcast session are reserved (reserved) or configured. The air interface resource related to the multicast/broadcast session is reserved (reserved) or configured according to the base station where the terminal joining the multicast/broadcast service is located. The terminals joining the multicast/broadcast session are in the CM _ CONNECTED state. The authenticated terminal may be allowed to join the multicast/broadcast session. A multicast/broadcast session in the active state may be converted to an inactive state (inactive). The Deactivation operation (Deactivation) may be triggered by an Application Function (AF)/Application Server (AS) request or may be a trigger that the UPF receives multicast/broadcast service data.

In addition, the state of the multicast/broadcast session may be a release/delete state, and the state of the multicast/broadcast session may be a release/delete state: the method comprises the steps of releasing/deleting the multicast/broadcast session when a service provider (content provider) starts/initiates/starts (inter) the multicast/broadcast session release/deletion (MBS session delete or MBS session release or session delete), releasing/deleting the information related to the multicast/broadcast session at a terminal and an access network side in the execution process of releasing/deleting the multicast/broadcast session or after the multicast/broadcast session is released/deleted, and releasing/deleting the information related to the multicast/broadcast session at a first session management function network element and/or a second session management function network element. Specifically, the release/deletion of the multicast/broadcast session may refer to: information related to the multicast/broadcast service (e.g., qoS information related to the multicast/broadcast service, etc.) is released/deleted in the terminal; the method comprises the steps of releasing/deleting information related to the Multicast/Broadcast Service at an access network device (for example, releasing/deleting the context related to the Multicast/Broadcast Service (for example, the Multicast/Broadcast context or the Multicast/Broadcast Service Session context or the Multicast/Broadcast group context or the Multicast/Broadcast Service context), releasing/deleting tunnel information related to the Multicast/Broadcast Session, releasing/deleting air interface resources related to the Multicast/Broadcast Session, releasing/deleting information related to the Multicast/Broadcast Service in the context of a terminal stored by the access network device, releasing/deleting the tunnel related to the Multicast/Broadcast Session, releasing/deleting the information related to the Multicast/Broadcast Service at a first Session management function network element and a second Session management function network element, and the like.

In the case that the method shown in fig. 5 is executed by an access network device, the access network device may determine that a multicast session is in a deactivated state by: if the duration that the access network equipment does not receive the data of the multicast service on the multicast session is longer than the preset duration, the access network equipment determines to deactivate the multicast session, releases the air interface resources allocated to the multicast session, and the multicast session is in a deactivated state. Or, if there is no terminal receiving the multicast service data in the terminals served by the access network device, the access network device determines to deactivate the multicast session of the multicast service, releases the air interface resource allocated for the multicast session, releases the tunnel information related to the multicast session, and so on, and the multicast session is in a deactivated state. Or, the access network device receives ninth information from the second access and mobility management function network element, where the ninth information may be sent by the second session management function network element to the second access and mobility management function network element, and the ninth information may be used to indicate/notify a multicast session for deactivating a multicast service (for example, the ninth information may be session stop (session stop), multicast broadcast service session deactivation (MBS session deactivation), or multicast session deactivation (multicast session deactivation), and the access network device determines to deactivate the multicast session according to the ninth information, releases air interface resources allocated for the multicast session, releases tunnel information related to the multicast session, and makes the multicast session in a deactivated state.

In the case where the method shown in fig. 5 is performed by an access network device, the access network device may determine that a multicast session is active by: and if the access network equipment receives the data of the multicast service on the multicast session, the access network equipment determines that the multicast session is in an activated state. Or, if there is a terminal receiving the multicast service data in the terminals served by the access network device, the access network device determines that the multicast session is in an active state. Or, if the access network device locally has context information related to the multicast session (for example, a multicast/broadcast service context, a multicast/broadcast group context, a multicast/broadcast session context, or a multicast/broadcast context), or the access network device does not release air interface resources allocated for the multicast session and tunnel information related to the multicast session, the access network device determines that the multicast session is in an active state.

The ninth information may carry explicit indication information, where the indication information is used to indicate/notify to deactivate the multicast session, or the ninth information may be used to carry indication information used to indicate multicast session deactivation (MBS session stop) or multicast broadcast service session deactivation (MBS session deactivation) or multicast session deactivation (multicast session deactivation), or indication/notification/report information used to indicate that the second user plane functional network element does not detect the data of the multicast service, and indirectly indicate to deactivate the multicast session through the information carried by the ninth information.

Further, if the multicast session is active, it may be determined whether to activate the PDU session according to a PDU session associated with the multicast session. Specifically, the method may be as described with reference to S503 a. Or, whether to activate the PDU session is determined according to the PDU session condition associated with the multicast session and the capability information. Specifically, this method can be described with reference to S503b described below.

S503a: and if the PDU session is associated with the multicast session and the multicast session is in an active state, keeping the state of the PDU session in the active state.

The state of maintaining the PDU session in the active state may include maintaining an air interface resource allocated to the PDU session and/or establishing a transmission tunnel corresponding to the PDU session between the access network device and the first user plane function network element.

Specifically, if the method shown in fig. 5 is executed by the access network device, the PDU session is associated with the multicast session, and the multicast session is in AN active state, and if data of the multicast service arrives at the access network device through the multicast session for air interface transmission, the access network device does not execute/initiate AN release flow. If the method shown in fig. 5 is executed by the first session management function network element, when the PDU session is associated with the multicast session and the multicast session is in an active state, the first session management function network element does not execute the deactivation of the associated PDU session.

The AN release flow is used for triggering the core network element to release the PDU session of the first terminal. The AN release flow may include: the method includes that an access network device sends information for indicating or notifying the deactivation of a PDU session to a first session management function network element through a first access and mobility management function network element, for example, the access network device sends N2 UE Context Release Complete (N2 UE Context Release Complete) to the first access and mobility management function network element, then the first access and mobility management function network element sends a serving interface Nsmf _ PDU session update session management Context request (Nsmf _ PDU session _ update smcontext request) to the first session management function network element, the Nsmf _ PDU session _ update smcontext request carries information for indicating the deactivation of the PDU session, and the first session management function network element is triggered to Release an air interface resource corresponding to the PDU session.

It should be noted that, in this embodiment of the application, in a case that the method shown in fig. 5 is executed by the first session management function network element, even if the first session management function network element determines that the PDU session associated with the multicast session needs to be deactivated, since the first session management function network element finds/determines that the PDU session is associated with the multicast session and the multicast session is in an active state, the first session management function network element does not execute a deactivation procedure of the associated PDU session, and keeps the PDU session in the active state.

Wherein the first session management function network element may determine (terminate) PDU session required (need) deactivation (inactive) according to: and the anchor point UPF (PSA UPF) corresponding to the PDU session does not detect the arrival of service data in the PDU session within a period of time, the PSA UPF sends an instruction/notice for deactivating the PDU session to the first session management function network element, and the first session management function network element receives the instruction/notice for deactivating the PDU session sent by the PSA UPF and determines that the PDU session needs to be deactivated.

In this embodiment of the present application, the deactivation procedure of the PDU session may include releasing an N3 tunnel of the PDU session and/or an air interface resource (e.g., DRB) corresponding to the PDU session.

S503b: if the PDU session is associated with the multicast session, the multicast session is in an active state, and the access network equipment corresponding to the PDU session does not support the multicast function, the PDU session is kept in the active state.

The maintaining of the state of the PDU session as the active state may include maintaining an air interface resource allocated to the PDU session and/or establishing a transmission tunnel corresponding to the PDU session between the access network device and the first user plane function network element.

Specifically, if the method shown in fig. 5 is executed by the first session management function network element, the PDU session is associated with the multicast session and the multicast session is in an active state, the first session management function network element determines whether the access network device supports the multicast function, and if the first session management function network element determines that the access network device corresponding to the PDU session does not support the multicast function, the first session management function network element does not execute the deactivation of the associated PDU session, and maintains the state of the PDU session as the active state. And if the first session management function network element determines that the access network equipment corresponding to the PDU session supports the multicast function, the first session management function network element performs the deactivation of the associated PDU session, namely, deactivates the PDU session associated with the multicast session.

When the access network device does not support the multicast function, as shown in fig. 3c, the multicast/broadcast service data needs to be transmitted in a 5G core network by a single multicast/broadcast service traffic transmission (5 GC industrial MBS traffic transmission) manner, that is, the multicast/broadcast service data is sent to the terminal device through the PDU session associated with the terminal device that joins the multicast service. Because the multicast/broadcast service data needs to be transmitted through the associated PDU session when the base station does not support the multicast function, since the transmission period of the multicast/broadcast service data may be longer than the transmission period of the data (which may be referred to as data of unicast service) transmitted on the PDU session, that is, the multicast/broadcast service data is transmitted once a day, but the inactivity timer (inactivity timer) set in the anchor UPF (such as PSA UPF) of the PDU session is one hour, at this time, when the inactivity timer expires (that is, it is detected that there is no data transmission of service in this timer on the PDU session), the PDU session cannot be deactivated, because the multicast/broadcast session is still active, the data of the multicast/broadcast service corresponding to the multicast/broadcast session needs to be transmitted through this PDU session.

In this embodiment of the present application, the first session management function network element may determine whether the access network device corresponding to the PDU session supports a multicast function according to the following manner: the first session management function network element acquires capability information from access network equipment corresponding to the PDU session through the first access and mobility management network element, wherein the capability information is used for indicating whether the access network equipment supports a multicast function, and the first session management function network element determines whether the access network equipment supports the multicast function according to the capability information, for example, if the capability information indicates that the access network equipment supports the multicast function, the access network equipment is determined to support the multicast function, otherwise, if the capability information indicates that the access network equipment does not support the multicast function, the access network equipment is determined not to support the multicast function.

In this embodiment of the present application, for example, in S503a or S503b, activating a PDU session associated with a multicast session may include: after the first session management function network element receives the second information for activating the multicast session, the first session management function network element sends a Namf _ Communication _ N1N2message transfer message containing an N2 session management message (N2 SM information) or a PDU session context update Response (Nsmf _ PDU _ usage _ update _ smcontext Response) containing an N2 SM information to the access network device, so as to trigger the access network device to activate a PDU session associated with the multicast session according to the N2 SM information, for example, to establish an air interface resource and a transmission tunnel corresponding to the PDU session. Further, after the access network device activates the PDU session associated with the multicast session, a reply message for the N2 SM information may also be sent to the first session management function network element.

The N2 SM information may include identification information of a multicast service (e.g., identification information of a multicast broadcast service session (MBS session)). Optionally, the N2 SM information may further include an instruction to join the terminal into the multicast session; optionally, the N2 SM information may further include unicast QoS configuration information mapped/corresponding to QoS configuration (QoS profile) information of a multicast service corresponding to the multicast session.

If the N2SM information includes unicast QoS configuration information mapped/corresponding to QoS configuration (QoS profile) information of a multicast service corresponding to a multicast session, the access network device may configure an air interface resource (or referred to as a radio bearer) for transmitting data of the multicast service according to the unicast QoS configuration information, and after the air interface resource is established, if a transmission tunnel between the access network device and a UPF is not established, the access network device includes downlink tunnel information (such as NG-U transport layer information or NG-RAN node end point) in a reply message for the N2SM information sent to the first session management function network element, where the downlink tunnel information is a necessary cell in a response message, and the downlink tunnel information may be used to establish the transmission tunnel for transmitting data of the multicast service between the access network device and the UPF, so as to ensure that a PDU session associated with the multicast session is activated.

S504: and if the PDU session is associated with the multicast session and the multicast session is in a deactivation state, deactivating the PDU session.

Deactivating the PDU session may include releasing an air interface resource allocated to the PDU session and/or releasing a transmission tunnel corresponding to the PDU session between the access network device and the first user plane function network element.

It should be noted that, in the case that the method shown in fig. 5 is executed by the access network device, if the access network device receives fifth information of the first session management function network element and determines, according to the fifth information, that a PDU session is to be deactivated, if the PDU session state is kept in an active state, the access network device sends sixth information to the first session management function network element, where the sixth information is used to indicate that the PDU session is rejected to be deactivated; if the PDU session is deactivated, the access network equipment sends seventh information to the first session management function network element, and the seventh information is used for indicating that the PDU session is deactivated, so that the access network equipment side and the first session management function network element side can synchronize the state of the PDU session and the state of the multicast session.

The access network device may interact information with the first session management function network element through the first access and mobility management function network element, for example, the access network device may send sixth information to the first session management function network element through the first access and mobility management function network, or send seventh information to the first session management function network element through the first access and mobility management function network.

Further, if the first session management function network element deactivates the PDU session, in order to ensure normal transmission of data of the multicast service, the method may further include: and the first session management function network element determines to send the data of the multicast service through the PDU session, injects/maps the data of the multicast service transmitted by the multicast session into the PDU session, and transmits the data of the multicast service corresponding to the associated multicast session through the PDU session. It should be noted that the PDU session may be a PDU session associated with a multicast session, or may not be a PDU session associated with a multicast session, but other PDU sessions of the first terminal that are in an active state/not released, which is not limited.

The determining, by the first session management function network element, that the data of the multicast service is transmitted through the PDU session may include: the first session management function network element sends the tunnel information of the first user plane function network element to the second user plane function network element, and notifies the second user plane function network element to establish a channel for transmitting data of the multicast service between the first user plane function network element and the second user plane function network element, for example, the first session management function network element sends the tunnel information of the first user plane function network element to the second session management function network element, the second session management function network element sends a session update request (for example, an N4 session update request) carrying the tunnel information of the first user plane function network element to the second user plane function network element, and the second user plane function network element receives and correspondingly stores the tunnel information of the first user plane function network element. Further, the second user plane function network element sends a session update response (which may be, for example, an N4 session update response) to the second session management function network element. Meanwhile, the first session management function network element configures the first user plane function network element according to the information of the multicast service and the mapping relationship between the multicast QoS stream and the unicast QoS stream included in the multicast service, for example, the first session management function network element sends the information of the multicast service and the QFI of the unicast QoS stream mapped by the quality of service (QoS) stream to the first user plane function network element, so as to map/inject the multicast QoS stream into a PDU session tunnel of a PDU session and transmit the multicast QoS stream in a unicast QoS stream manner, wherein the information of the multicast service may include identification information of the multicast service; the method may further include a Packet Detection Rule (PDR), and for the filtered data of the multicast service, the first user plane functional network element maps the data of the multicast service into the PDU session according to a mapping relationship between the QFI of the multicast QoS stream and the QFI of the unicast QoS stream, and transmits the data in a unicast QoS stream manner.

Further, in the case that the method shown in fig. 5 is executed by the first session management function network element and the multicast session is in a deactivated state, the method further includes: the first session management function network element receives second information from the second session management function network element; and the first session management functional network element determines to activate the multicast session according to the second information, and informs the access network equipment to add the first terminal into the multicast group through the first access and mobility management functional network element. Or, the first session management function network element receives second information from the second session management function network element, determines to activate the multicast session according to the second information, and notifies the access network device to add the first terminal to the multicast group through the first access and mobility network element mobility management function network element.

The description of the second information may refer to the description in S502, which is not repeated.

It should be noted that, before the first session management function network element notifies the access network device to join the first terminal to the multicast group through the first access and mobility management function network element, if the PDU session associated with the multicast session is not in an active state, the first session management function network element also activates the PDU session associated with the multicast session.

The process of activating the PDU session and notifying the access network device to join the first terminal device to the multicast group may be: and the first session management function network element activates a PDU session related to the multicast session, and sends a Namf _ Communication _ N1N2MessageTransfer message to the first access and mobility management function network element, wherein the Namf _ Communication _ N1N2MessageTransfer message can carry identification information of the multicast group. After the first access and mobility management function network element receives the message, if the first terminal is in a connected state, the first access and mobility management function network element continues to interact with the access network equipment to execute the PDU session associated with subsequent flow activation. If the first terminal is in a CM-IDLE state, the first access and mobility management function network element and the access network equipment perform paging for a single UE or group paging for the multicast group, after the first terminal receives a paging message, the first terminal initiates a service request (service request) process to activate and associate a PDU session, and then the first session management function network element informs the access network equipment to add the first terminal into the multicast group through a signaling related to the terminal in the multicast group. Specifically, the process may include:

After the first session management function network element receives MBS session start/MBS session activation/session start or multicast session activation (MBS session activation) or multicast session activation (multicast session activation) sent by the second session management function network element, or receives information of data arrival of a multicast service reported/notified/indicated by the first user plane function network element, the first session management function network element sends an N11 message (for example, N1N2message transfer (Namf _ Communication _ N1N2message transfer)) to the first access and mobility management function network element, where the N11 message may carry identification information of a multicast group. If the first access and mobility management function network element finds that a plurality of terminals in a CM-CONNECTED state exist in the terminals which are managed by the first access and mobility management function network element and are in the multicast group, the first access and mobility management function network element continues to carry out interactive activation associated PDU session with access network equipment and the like; if a plurality of terminals in the CM-IDLE state exist, a first terminal is included in the plurality of terminals in the CM-IDLE state, a first access and mobility management function network element initiates 1 or more paging messages to page one or more terminals in the CM-IDLE state, the paging messages correspond to the plurality of terminals in the CM-IDLE state one by one, one paging message faces one terminal, and one paging message is used for paging one terminal in the CM-IDLE state; or, the first access and mobility management function network element initiates a group paging, for example, initiates a paging message for paging a plurality of terminals in a CM-IDLE state in a multicast group, where the paging message may carry identification information of the multicast group (e.g., one or more of TMGI, MBS session ID, identifier of multicast service, multicast address, multicast IP address, identifier of multicast group, identifier of multicast session, context information of multicast session, address information of multicast service, identification information of PDU session associated with multicast session, service data stream SDF identification information of multicast service, etc.), and the identification information of the multicast group may be the same as the identification information of multicast service, which is not limited. The identification information of the multicast group is obtained from the first session management function by the first access and mobility management function element, thereby returning the plurality of terminals in the CM-IDLE state to the CM-CONNECTED state through one paging message. After the terminals (including the first terminal) in the multicast group receive the paging message, if the PDU session associated with the multicast service is found to be still in an inactive state, a service request (service request) process is initiated to activate the PDU session associated with the multicast session, and the service request process may refer to the prior art and is not described in detail. Further, after the PDU session associated with the multicast session is activated, the access network device is notified to join the first terminal to the multicast group.

The embodiment of the present application is not limited to the first session management function network element sending an N11 message carrying identification information of a multicast group to the first access and mobility management network element, alternatively, the first session management function network element may send a third message to the first access and mobility management network element, where the third message may be an N11 message, and the third message may include identification information of the first terminal, where the third message may be used by the first access and mobility management network element to know, according to an indication of the first session management function network element, which terminals join the multicast group are, and when the first terminal in the multicast group is in an IDLE state or a CM-IDLE state, trigger the first access and mobility management network element to initiate paging in a registration area of the first terminal, so that the first access and mobility management network element may determine, according to the identification information of the terminal, to initiate paging to the terminal in an IDLE state or a CM-IDLE state. Specifically, the process of initiating paging by the first access and mobility management network element is as described above, for example, the first access network device may send one or more paging messages, where one paging message corresponds to paging a terminal; or, the first access network device sends a group paging, for example, sends a group paging message corresponding to multiple terminals, where the group paging message may include identification information of a multicast service, and thus, paging multiple terminals at a time through group paging is implemented.

It should be noted that, when there are multiple terminals in the CM-IDLE state in the multicast group and there are areas where registration areas of the multiple terminals overlap with each other (which may be referred to as overlapping areas herein), in order to save signaling overhead, the first access and mobility management function network element may initiate group paging in the overlapping area of one terminal without repeatedly initiating group paging in the overlapping area of the registration area of each terminal. For example, a second terminal in a CM-IDLE state also exists in the multicast group, and the identification information of the multicast group is further used for initiating group paging in a region other than an overlapping region in the registration region of the second terminal when the first access and mobility management functional network element finds that the second terminal is in an IDLE state, where the overlapping region may be a region where the registration region of the first terminal and the registration region of the second terminal overlap each other. Therefore, the first access and mobility management network element can repeatedly initiate group paging without the overlapping area of the registration area of each terminal in the CM-IDLE state in the multicast group, and the purpose of saving signaling overhead is achieved.

It should be noted that in the embodiment of the present application, the first terminal may include one or more terminals. When the first terminal includes multiple terminals, the sending, by the first session management function network element, the identification information of the first terminal to the first access and mobility management function network element may instead be described as sending, by the first session management function network element, a UE list to the first access and mobility management function network element, where the UE list may include identification information of multiple terminals joining the multicast session.

It should be noted that, for a terminal in the CM-CONNECTED state in the multicast group, the first session management functional network element may activate a PDU session associated with the terminal, and then interact with the access network device and other core network devices to join the first terminal into the multicast group, or interact with the access network device and other core network devices to join the first terminal into the multicast group, and then activate the associated PDU session, or interact with the access network device and other core networks to join the first terminal into the multicast group and activate the associated PDU session at the same time, which is not limited.

For a terminal in the CM-IDLE state in the multicast group, after the terminal receives the paging message and performs the service request procedure (for example, after the associated PDU session is activated), the first session management function network element may interact with the access network device and other core network devices to join the first terminal into the multicast group, or, after the terminal receives the paging message and performs the service request procedure (for example, although the CM-CONNECTED state is returned, the associated PDU session is not activated yet), the first terminal may interact with the access network device and other core network devices to join the first terminal into the multicast group and then activate the associated PDU session, or the first session management function network element may interact with the access network device and other core networks to join the first terminal into the multicast group and activate the associated PDU session simultaneously, which is not limited.

For example, assuming that the UE is in the CM-CONNECTED state, the UE has three PDU sessions, PDU session identifier =1, PDU session identifier =3, and PDU session identifier =5, and all three PDU sessions are in the inactive state, and the UE joins multicast session 1 through the PDU session identified by PDU session identifier 1, then the UE knows which PDU session is associated with which multicast session. When data on the PDU session with the PDU session identifier of 5 reaches the UPF, the network side equipment triggers a service request flow, if the UE is in a CM-CONNECTED state (for example, at least one PDU session in 1,3 and 5 is in an activated state), the first SMF only needs to continuously execute a subsequent service request flow to activate the associated PDU session with the identifier of 1; if the UE is in the CM-IDLE state (i.e. all

numbers

1,3,5 are deactivated), the AMF will send a paging or group paging message after receiving the above N11 message sent by the first SMF, and the UE will initiate a service request procedure initiated by the UE to activate a PDU session associated with multicast after receiving the paging or group paging message. Then, the access network device is notified to add the UE to the multicast group, or the UE in the CM-CONNECTED state is added to the multicast group first, and if the associated PDU session is in the deactivated state, the associated PDU session is activated, which is not limited.

For example, the first session management function network element notifies the access network device to add the first terminal to the multicast group, and may also replace the allocation of air interface resources for activating a multicast session or for the terminal to receive data of a multicast service, the radio bearer configuration for receiving data of the multicast service, and the like. In embodiments of the present application, the notifying, by the first session management function network element, the access network device to join the first terminal to the multicast group may include: the first session management function network element joins the first terminal to the multicast group by interacting with an access network device (e.g., RAN) and other core network elements (e.g., AMF, MB-SMF, etc.).

Specifically, the step of the first session management function network element notifying the access network device to add the first terminal to the multicast group may be: when the data of the multicast service is transmitted or distributed through the multicast session, the first session management function network element notifies the access network device to allocate the air interface resource related to the multicast session for the first terminal through the signaling related to the UE, and the access network device adds the first terminal into the multicast group. Optionally, the access network device may further interact with one or more network elements of AMF, SMF, MB-SMF, and MB-UPF to establish a multicast session tunnel between the access network device and the MB-UPF. Or, when the data of the multicast service is transmitted or distributed through the PDU session of the UE, the first session management function network element notifies the access network device and the first user plane network element to allocate resources for transmitting the QoS stream related to the multicast service corresponding to the multicast session, and establishes a tunnel between the first user plane network element and the second user plane network element, and the like.

Based on the method shown in fig. 5, in the process of deactivating a PDU session, a multicast session associated with the PDU session may be considered, and if the multicast session associated with the PDU session is in an active state, the PDU session is not deactivated, and the PDU session is maintained in the active state, so that data of a multicast service is subsequently mapped/injected onto the PDU session in a certain application scenario (for example, a handover scenario), so as to ensure normal transmission of data of the multicast service, or, when the PDU session is the last PDU of a terminal, the terminal enters an idle state after the PDU session is deactivated, so that the terminal cannot receive data of the multicast service through an air interface resource. If the multicast session associated with the PDU session is in a deactivated state, the PDU session is deactivated, transmission resources are saved, and the resource utilization rate is improved.

With reference to the 5G system shown in fig. 3a, the method shown in fig. 5 executed by the access network device is described in detail below by taking the first terminal as a UE, the access network device as a RAN, the first session management function network element as a first SMF, the second session management function network element as an MB-SMF/second SMF, the first user plane function network element as a UPF, the second user plane function network element as an MB-UPF, and the access and mobility management function network element as an AMF. It should be noted that, in the present application, the UPF may be integrated with the MB-UPF, and the integrated UPF may have the functions of both the UPF and the MB-UPF described in the present application, or the UPF and the MB-UPF may be deployed independently, without limitation. In this application, the SMF may be integrated with the MB-SMF, and the integrated SMF may have both the functions of the SMF and the MB-SMF described in this application, or the SMF and the MB-SMF may be deployed independently without limitation.

Fig. 6 is a flowchart of a communication method provided in an embodiment of the present application, configured to determine, when a RAN deactivates a PDU session, a state of a multicast session associated with the PDU session, and then determine whether to deactivate the PDU session according to the state of the multicast session associated with the PDU session. As shown in fig. 6, the method includes:

s601: the RAN determines to deactivate the PDU session for the UE.

The PDU session of the UE corresponds to the first SMF and the UPF. The RAN determining to deactivate the PDU session of the UE may also be alternatively described as the RAN determining to deactivate the PDU session of the UE, without limitation.

For example, the RAN may determine to deactivate the PDU session of the UE in any one of four ways: in the mode (1), if the RAN does not receive the data transmitted on the PDU session of the UE for a long time, it is determined to deactivate the PDU session of the UE. And (2) if the UE moves out of the service area of the RAN and the UE is not reachable and the RAN does not provide network service for the UE any more, the RAN determines to deactivate the PDU session of the UE. Mode (3), if the UE is in radio access control idle (RRC _ idle) state or inactive (RRC _ inactive) state, the RAN determines to deactivate the PDU session of the UE. Mode (4), the RAN receives fifth information from the first SMF, where the fifth information may be information indicating that the PDU session of the UE is stopped or information indicating that the UPF does not detect data addressed to the UE or information indicating that the PDU session is deactivated, and the RAN determines to deactivate the PDU session of the UE according to the fifth information.

S602: the RAN determines whether the PDU session to be deactivated is associated with a multicast session.

The execution process of S602 may refer to S501, which is not described herein.

S603: the RAN determines whether the multicast session is in an active state, and if the PDU session is associated with the multicast session and the multicast session is in an active state, S604 is executed, and the process ends. Otherwise, executing S605-S610 and ending the process.

For example, if any one or more of the following event 1 to event 3 is performed (or occurs), it is determined that the multicast session is in a deactivated state, and otherwise, if none of the event 1 to event 3 occurs, it is determined that the multicast session is in an activated state.

Event 1: RAN does not receive the data of the multicast service transmitted on the multicast session for a long time; or, if the RAN does not have the UE receiving the data of the multicast service, the RAN determines to deactivate the multicast session, and releases the air interface resource allocated for the multicast session, so that the multicast session is in a deactivated state.

Further, when the RAN determines to deactivate the multicast session, the RAN may also delete/remove/release the context of the multicast session (alternatively referred to as multicast context) stored in the RAN.

Further, event 1 may also include: and the RAN sends a notification message for deactivating the multicast session to the first SMF, or the RAN sends a notification message for deactivating the multicast session to the MB-SMF. The RAN sending a notification message to the first SMF to deactivate the multicast session may include: RAN sends N2message (N2 message) carrying notification message for deactivating multicast session to AMF, AMF receives N2message sent by RAN, and then locates first SMF corresponding to PDU session according to PDU session ID carried in N2message, AMF carries notification message in N11 message and sends the notification message to first SMF.

The sending, by the RAN, the notification message for deactivating the multicast session to the MB-SMF may include: the RAN sends an N2message (N2 message) carrying a notification message for deactivating the multicast session to the AMF, after the AMF receives the N2message sent by the RAN, the MB-SMF is determined (positioned) according to the identification information of the multicast service carried in the N2message and the corresponding relation between the identification information of the multicast service and the identification information of the MB-SMF, the corresponding relation between the identification information of the multicast service and the identification information of the MB-SMF can be known by the AMF when the UE joins the multicast service, and the notification message is carried in the N11 message by the AMF and sent to the MB-SMF.

Further, after receiving the N11 message, the MB-SMF performs session update (e.g., N4 session update) with the MB-UPF according to the notification message carried in the N11 message, for example, the MB-SMF sends a session update request (e.g., N4 session update request) to the MB-UPF. Further, the MB-SMF receives a session update response (e.g., N4 session update response) from the MB-UPF.

Optionally, if the MB-SMF does not notify the MB-UPF to perform the caching of the data of the multicast service, the MB-SMF may also perform the caching of the data of the multicast service; optionally, the N4 session update request may also be used to instruct the MB-UPF to notify the MB-SMF when data of the multicast service arrives at the MB-UPF. Optionally, the N4 session update request may also carry a release notification for releasing the multicast session tunnel. It should be noted that the notification may be carried in the N4 session update request as a cell, alternatively, may also be carried in a special N4 message, and is not limited.

If the MB-UPF receives the release notice of the multicast session tunnel, the MB-UPF removes the tunnel information related to the multicast session tunnel, such as the tunnel endpoint identification information of the RAN side of the multicast session tunnel between the MB-UPF and the RAN. And then the MB-UPF sends an N4 session update response to the MB-SMF, and the MB-SMF receives the N4 session update response and sends a response of the second message to the first SMF.

When the notification message is carried in the N2 message, the notification message may be an indication (indication) carried in the N2 message or a cause value (cause) for sending the N2 message, where the cause value indicates that the cause for triggering the sending of the N2 message is due to the multicast session deactivation. The N2 message may be a new type of N2 message or may be a UE-related N2 message, such as an N2 message related to a PDU session associated with a multicast session that is currently active. The N2 message may carry an ID of the PDU session associated with the multicast session. In addition, optionally, the N2 message may also carry identification information of a multicast service corresponding to the deactivated multicast session. Similarly, when the notification message is carried in the N11 message, the notification message may be an indication carried in the N11 message or a cause value for sending the N11 message, where the cause value indicates that the cause for triggering the sending of the N11 message is due to the multicast session deactivation, and the N11 message may be a new type of N11 message, or may be an N11 message related to a PDU session associated with the multicast session, or a PDU session context update Request (Nsmf _ PDU _ update _ PDU _ context Request).

Optionally, if the RAN determines to release the multicast session tunnel between the RAN and the MB-UPF, the RAN may further include a release notification of the multicast session tunnel in the notification message, where the release notification may be an indication in the notification message to indicate that the multicast session tunnel is released.

In embodiments of the present application, the determining, by the MB-SMF, the first SMF to join the multicast service may include: the determining, by the MB-SMF, the first SMF joining the multicast service according to the identification information of the multicast service may include: the MB-SMF may locally search for the context corresponding to the multicast service by using the identification information of the multicast service as an index or obtain the context corresponding to the multicast service from the UDR (for example, the context may be a multicast service context, a multicast group context, a multicast service context, a context of a multicast session, or the like), and the MB-SMF checks a list of SMFs in the context corresponding to the multicast service, and determines an SMF in the list as the first SMF. When a UE joins a multicast service or a multicast session or a multicast group through an SMF, when an MB-SMF receives information (e.g., multicast QoS information) of the SMF related to acquiring the multicast session or the multicast service for the first time, the SMF is added to an SMF list related to the multicast service or the multicast group.

When the last UE in the SMF leaves the multicast group or the multicast service, the SMF sends a message to the MB-SMF, and after the MB-SMF receives the message, the SMF is deleted from the SMF list of the multicast service or the multicast group.

Event 2: and the AS/CP sends a multicast session stop (MBS session stop) message to the MB-SMF, wherein the message contains the identification information of the multicast service corresponding to the multicast session needing to be stopped (or deactivated). And the MB-SMF receives the message of stopping the multicast session, updates the N4 session by the MB-SMF and the MB-UPF and informs the MB-UPF of deactivating the multicast session or stopping the multicast session. Further, the MB-SMF may determine whether to release the multicast session tunnel, and if it is determined to release the multicast session tunnel, notify the MB-UPF to release the multicast session tunnel when performing N4 session update with the MB-UPF. After receiving the message of stopping the multicast session, the MB-SMF determines the first SMF joining the multicast service, and sends the first information to the first SMF, where the first information may be used to indicate multicast session stop (MBs session stop) or directly indicate to deactivate the multicast session, for example, multicast broadcast service session deactivation (MBs session deactivation) or multicast session deactivation (multicast session deactivation). Optionally, if the MB-SMF determines to release the multicast session tunnel, the eighth information further includes a message for releasing the multicast session tunnel. And the first SMF receives the seventh message sent by the MB-SMF, determines whether a PDU session associated with the multicast session service exists according to the identification information of the multicast service, and if so, the first SMF sends N1N2 message transfer to the AMF. The AMF receives the N1N2 message transmission, and sends an N2 message to the RAN, where the N2 message may carry the first information. And after receiving the first information, the RAN determines to deactivate the multicast session and releases the air interface resources allocated to the multicast session.

Or, the MB-SMF sends a multicast session stop (MBs session stop) or multicast broadcast service session deactivation (MBs session deactivation) or multicast session deactivation (multicast session deactivation) message to the AMF, the AMF forwards the message to the RAN, and the RAN determines to deactivate the multicast session and release the air interface resource allocated to the multicast session after receiving the multicast session stop (MBs session stop) or multicast broadcast service session deactivation (MBs session deactivation) or multicast session deactivation message.

Event 3: the MB-UPF does not detect the data of the multicast service for a long time, and the MB-UPF sends a message of not detecting the data of the multicast service to the MB-SMF, wherein the message comprises the identification information of the multicast service of which the data is not detected. The MB-SMF receives a message that the data of the multicast service is not detected, the MB-SMF sends a response message to the MB-UPF, and informs the MB-UPF to deactivate the multicast session and cache the data of the multicast service, or sends a notice to the MB-SMF when the data of the multicast service reaches the MB-UPF, and the like. Further, the MB-SMF may determine whether to release the multicast session tunnel, and if it is determined to release the multicast session tunnel, may also notify the MB-UPF to release the multicast session tunnel. After receiving the message that the data of the multicast service is not detected, the MB-SMF determines a first SMF joining the multicast service, and sends first information to the first SMF, where the first information may be used to indicate that the data of the multicast service is not detected or directly indicate that the multicast session is deactivated. Optionally, if the MB-SMF determines to release the multicast session tunnel, the eighth information further includes a message for releasing the multicast session tunnel. And the first SMF receives the first information sent by the MB-first SMF, determines whether a PDU session associated with the multicast session service exists, and if so, the first SMF sends N1N2 message delivery to the AMF. The AMF receives the N1N2 message transmission, and sends an N2 message to the RAN, where the N2 message may carry the first information. And after receiving the first information, the RAN determines to deactivate the multicast session and releases the air interface resources allocated to the multicast session.

Or, the MB-SMF sends a message of not detecting the data of the multicast service to the AMF, the AMF forwards the message to the RAN, and the RAN determines to deactivate the multicast session and release the air interface resource allocated to the multicast session after receiving the message of not detecting the data of the multicast service.

Further optionally, if the RAN further receives a release notification of the multicast session tunnel, the RAN may also delete (or remove) the context (e.g., multicast context) of the multicast session stored in the RAN. Optionally, if the context of the multicast session is released, the RAN releases the transport tunnel corresponding to the multicast session between the RAN and the MB-UPF.

S604: the RAN maintains the state of the PDU session as active.

If the RAN determines to deactivate the PDU session in S601 by using the method (4), further, the access network device sends sixth information to the first session management function network element, for example, the sixth information is sent to the first SMF by the first AMF, where the sixth information is used to indicate that the PDU session is rejected to be deactivated, and the first AMF corresponds to the PDU of the UE.

S605: the RAN deactivates the PDU session.

S606: the RAN sends seventh information to the first SMF, wherein the seventh information is used for indicating that the PDU conversation is deactivated.

Illustratively, the RAN may send the seventh information to the first SMF via the first AMF.

S607: and the first SMF receives seventh information sent by the RAN and determines to transmit data of the multicast service through the PDU session.

It should be noted that the PDU session is any PDU session in an active state except for a deactivated PDU session.

The process of determining that the data of the multicast service is transmitted through the PDU session by the first SMF may refer to following S1004 to S1007, for example, the first SMF sends an N16MB message carrying tunnel information of the UPF corresponding to the PDU session to the MB-SMF. And the MB-SMF receives the N16MB message, the MB-SMF and the MB-UPF carry out N4 session updating, the tunnel information of the UPF is sent to the MB-UPF, and a channel for transmitting the data of the multicast service between the MB-SMF and the UPF is established. Meanwhile, the first SMF and the UPF perform N4 session update, and map the multicast QoS stream of the multicast service into a PDU session tunnel of the PDU session for transmission in a unicast QoS stream manner, for example, the first SMF sends the information of the multicast service and the QFI of the unicast QoS stream mapped by the multicast QoS stream to the UPF, so as to map the multicast QoS stream into the PDU session tunnel of the PDU session for transmission in a unicast QoS stream manner, where the information of the multicast service may include identification information of the multicast service, and may further include a PDR and the like, and for the filtered data of the multicast service, the UPF maps the data of the multicast service into the PDU session according to the mapping relationship between the QFI of the multicast QoS stream and the QFI of the unicast QoS stream for transmission in a unicast QoS stream manner.

S608: the first SMF sends the third information to the UPF. Accordingly, the UPF receives the third information.

And the third information is used for indicating to monitor the data of the multicast service from the MB-SMF, and the fourth information is sent to the first SMF when the data of the multicast service from the MB-SMF reaches the UPF.

S609: and the UPF receives the data of the multicast service from the MB-UPF and sends the fourth information to the first SMF. Accordingly, the first SMF receives the fourth information from the UPF.

Wherein the fourth information may be used to indicate that data of the multicast service is detected. For example, the UPF may send a user plane notification message, such as an N4 message, to the first SMF, where the N4 message may carry fourth information indicating that the data of the multicast service and the identification information of the multicast service are detected. Optionally, the fourth information for indicating that the data of the multicast service is detected may be carried in the N4 message as a cell, where the cell may be an indication or may be a cause value, that is, it indicates that the reason for sending the N4 message is an arrival notification of the data of the multicast service; alternatively, the fourth information indicating that data of the multicast service is detected may be sent by the UPF to the first SMF as a proprietary message, which may be a proprietary N4 message.

S607 to S609 are optional steps, may be executed or not executed, and are not limited.

S610: the first SMF receives the second message from the MB-SMF, and the first SMF notifies the RAN to join the UE to the multicast group. The first SMF activates a PDU session associated with the multicast session if the PDU session associated with the multicast session is in a deactivated state before the first SMF notifies the RAN to join the UE to the multicast group.

Specifically, the process in S610 may be described with reference to fig. 5, and is not repeated.

The first SMF notifies the RAN to add the UE to the multicast group, which may be described as activating a multicast session or allocating air interface resources to data of the multicast service received by the UE instead. The process of the first SMF notifying the RAN to join the UE to the multicast group may be described with reference to fig. 5, and is not described in detail.

In the following, referring to the 5G system shown in fig. 3a, the method shown in fig. 5 is performed on the first session management functional network element by taking the first terminal as a UE, the access network device as a RAN, the first session management functional network element as a first SMF, the second session management functional network element as an MB-SMF/second SMF, the first user plane functional network element as a UPF, the second user plane functional network element as an MB-UPF, and the access and mobility management functional network element as an AMF, for example. It should be noted that, in the present application, the UPF may be integrated with the MB-UPF, and the integrated UPF may have the functions of both the UPF and the MB-UPF described in the present application, or the UPF and the MB-UPF may be deployed independently, without limitation. In this application, the SMF may be integrated with the MB-SMF, and the integrated SMF may have the functions of both the SMF and the MB-SMF, or the SMF and the MB-SMF may be deployed independently without limitation. Fig. 7 is a flowchart of a communication method according to an embodiment of the present application, and as shown in fig. 7, the method includes:

S701: the first SMF determines to deactivate the PDU session for the UE.

For example, the first SMF may determine to deactivate the PDU session of the UE in any one of the following two ways: in the mode (1), the first SMF receives a notification of deactivating the PDU session sent by the RAN, and determines to deactivate the PDU session of the UE. And (2) the first SMF receives a notification that the data transmitted by the PDU session of the UE is not detected for a long time and sent by the UPF, and determines to deactivate the PDU session.

S702: the first SMF determines whether the PDU session to be deactivated is associated with a multicast session.

The execution process of S702 can be described with reference to S501, and is not described in detail.

S703: the first SMF determines whether the multicast session is active, and if the PDU session and the multicast session are associated and the multicast session is active, S704 is executed and the process ends. Otherwise, S705 is executed, and the process ends.

For example, if any one or more of the following event 1 to event 3 is completed (or occurs), it is determined that the multicast session is in a deactivated state, and otherwise, if none of the event 1 to event 3 occurs, it is determined that the multicast session is in an activated state.

Event 1: and the first SMF receives the indication/notification from the RAN to deactivate the multicast session, determines to deactivate the multicast session and marks the state of the multicast session as a deactivated state.

Event 2: the AS/CP sends a multicast Session stop (MBs Session stop or Session stop) message to the MB-SMF through the NEF or directly, where the message includes identification information of a multicast service corresponding to the multicast Session that needs to be stopped (or deactivated) (for example, the identification information of the multicast service may be a multicast IP address of a multicast group, or an ID, a name, or a group ID of the multicast group, etc.). The MB-SMF receives the message that the multicast session is stopped, and the MB-SMF performs a session update (e.g., N4 session update) with the MB-UPF and informs the MB-UPF of the deactivation of the multicast session or the stop of the multicast session. Further, the MB-SMF may determine whether to release the multicast session tunnel, and if it is determined to release the multicast session tunnel, notify the MB-UPF to release the multicast session tunnel when performing a session update (e.g., N4 session update) with the MB-UPF. After receiving the message of stopping the multicast session, the MB-SMF determines the first SMF joining the multicast service, and sends the first information to the first SMF, where the first information may be a message for indicating/notifying the stop of the multicast session or directly indicating the deactivation of the multicast session. Optionally, if the MB-SMF determines to release the multicast session tunnel, the first information further includes a message for releasing the multicast session tunnel. And the first SMF receives first information sent by the MB-SMF, determines to deactivate the multicast session according to the first information, and marks the state of the multicast session as a deactivated state.

Event 3: the MB-UPF does not detect the data of the multicast service for a long time, and the MB-UPF sends a message of not detecting the data of the multicast service to the MB-SMF, wherein the message comprises the identification information of the multicast service of which the data is not detected. The MB-SMF receives a message that the data of the multicast service is not detected, determines that the multicast session corresponding to the multicast service is deactivated, and sends a response message to the MB-UPF to inform the MB-UPF to cache the data of the multicast service when the multicast session is activated next time, or sends a notice to the MB-SMF when the data of the multicast service reaches the MB-UPF. Further, the MB-SMF may determine whether to release the multicast session tunnel, and if it is determined to release the multicast session tunnel, may also notify the MB-UPF to release the multicast session tunnel. After receiving the message that the data of the multicast service is not detected, the MB-SMF determines a first SMF joining the multicast service, and sends first information to the first SMF, where the first information may be used to indicate that the data of the multicast service is not detected or directly indicate that the multicast session is deactivated. Optionally, if the MB-SMF determines to release the multicast session tunnel, the first information further includes a message for releasing the multicast session tunnel. And the first SMF receives first information sent by the MB-SMF, determines to deactivate the multicast session according to the first information, and marks the state of the multicast session as a deactivated state.

S704: the first SMF maintains the state of the PDU session associated with the multicast session in an active state.

S705: the first SMF deactivates the PDU session.

S706: the first SMF determines to transmit data of the multicast service over the PDU session.

It should be noted that the PDU session is any PDU session in an active state except for the deactivated PDU session.

The process of determining that the data of the multicast service is transmitted through the PDU session by the first SMF may refer to following S1004 to S1007, for example, the first SMF sends an N16MB message carrying tunnel information of the UPF corresponding to the PDU session to the MB-SMF. And the MB-SMF receives the N16MB message, performs session update (for example, N4 session update) with the MB-UPF, sends the tunnel information of the UPF to the MB-UPF, and establishes a channel for transmitting data of the multicast service between the MB-SMF and the UPF. Meanwhile, the first SMF performs session update (for example, N4 session update) with the UPF, maps a multicast QoS stream of the multicast service into a PDU session tunnel of the PDU session, and transmits the multicast QoS stream in a unicast QoS stream manner, for example, the first SMF sends a session update request (for example, N4 session update request) carrying information of the multicast service and QFI of the unicast QoS stream mapped by the multicast QoS stream to the UPF, so as to map the multicast QoS stream into the PDU session tunnel of the PDU session and transmit the multicast QoS stream in a unicast QoS stream manner, where the information of the multicast service may include identification information of the multicast service, and may further include PDR and the like, and for the filtered data of the multicast service, the UPF maps the data of the multicast service into the PDU session according to a mapping relationship between the QFI of the multicast QoS stream and the QFI of the unicast QoS stream and transmits the unicast QoS stream in a unicast QoS stream manner. Further, the UPF returns a session update response (e.g., N4 session update response) to the first SMF.

S707: the first SMF sends the third information to the UPF. Accordingly, the UPF receives the third information.

It should be noted that the third information may be carried in a session update request and sent to the UPF during a session update (e.g., N4 session update) between the first SMF and the UPF, and at this time, step S707 may be combined to be executed during the session update between the first SMF and the UPF.

S708: and the UPF receives the data of the multicast service from the MB-UPF and sends the fourth information to the first SMF. Accordingly, the first SMF receives the fourth information from the UPF.

Wherein the fourth information may be used to indicate that data of the multicast service is detected. For example, the UPF may send a user plane notification message, such as an N4 message, to the first SMF, where the N4 message may carry fourth information indicating that the data of the multicast service and the identification information of the multicast service are detected. Optionally, the fourth information for indicating that the data of the multicast service is detected may be carried in the N4 message as an information element, where the information element may be an indication or a notification or may be a cause value, that is, it indicates that the reason for sending the N4 message is an arrival notification of the data of the multicast service; alternatively, the fourth information indicating that data of the multicast service is detected may be sent by the UPF to the first SMF as a proprietary message, which may be a proprietary N4 message.

S706 to S708 are optional steps, and may or may not be executed, and are not limited.

S709: the first SMF receives the second message from the MB-SMF, and the first SMF notifies the RAN to join the UE to the multicast group.

It should be noted here that the first SMF activates the PDU session associated with the multicast session if the PDU session associated with the multicast session is deactivated before the first SMF interacts with the RAN and other core network devices to join the UE to the multicast group. It should be noted here that, the SMF interacting with the RAN and other core networks to join the UE into the multicast group and activate the PDU session associated with the multicast session may be performed simultaneously, or the UE may join the UE into the multicast group first and then activate the PDU session associated with the multicast session, or may activate the PDU session associated with the multicast first and then join the UE into the multicast group, which is not limited.

Illustratively, for a UE in CM-CONNECTED state within a multicast group, if the associated PDU session is in a deactivated state, the first SMF (i.e., the first session management function network element) activates the associated PDU session; for the UE in the CM-IDLE state, the network side device may first perform group paging (group paging) or paging facing to a single UE, and after receiving the paging message, the UE initiates a first message, such as initiating a service request, and activates a PDU session associated with a multicast session by executing a service request procedure. The UE may be added to the multicast group after the PDU session associated with the multicast session is activated, or the UE may be added to the multicast group first and then the associated PDU session is activated, or the associated PDU session may be activated while the UE is added to the multicast group, which is not limited.

Specifically, the process of activating the PDU session associated with the multicast session may be described with reference to fig. 5, and is not described in detail.

For example, the first SMF may notify the RAN to join the UE to the multicast group, instead of allocating air interface resources for activating a multicast session or receiving data of a multicast service for the UE, and allocating radio bearer configuration for receiving data of the multicast service. The process of the first SMF notifying the RAN of joining the UE to the multicast group may be described with reference to fig. 5, and is not described in detail.

The methods shown in fig. 5-7 above take the example of the PDU session associated with the multicast session as an example, and determine whether to deactivate the PDU session by considering whether the multicast session of the PDU session is in a deactivated state. Alternatively, the present application further provides a communication method, where the communication method includes: when the first session management function network element receives the second information for activating the multicast session, the access network device is notified to add the first terminal to the multicast group corresponding to the multicast session, so that the first terminal is ensured to receive the data of the multicast service through the multicast session, and the resource utilization rate is improved. Or after receiving the second information for activating the multicast session, the first session management function network element activates the PDU session associated with the multicast session, for example, directly activates the PDU session associated with the multicast session, or activates the PDU session associated with the multicast session according to the multicast capability corresponding to the PDU session. A specific such method is illustrated with reference to fig. 8.

Fig. 8 is a flowchart of a communication method provided in an embodiment of the present application, where the method may be applied to a scenario where a multicast session is in a deactivated state, and as shown in fig. 8, the method may include:

s801: and the second session management function network element sends the second information to the first session management function network element.

The first session management functional network element may be a session management functional network element corresponding to a PDU session of the first terminal, the first session management functional network element may manage the PDU session of the first terminal, and the first terminal may be any terminal that joins a multicast group corresponding to the multicast service.

The second information may be used to indicate that a multicast session is activated, and the second information may include identification information of a multicast service or identification information of a multicast group (e.g., one or more of TMGI, multicast broadcast service session (MBS session ID), identification of a multicast service, multicast address, multicast IP address, identification of a multicast group, identification of a multicast session, context information of a multicast session, address information of a multicast service, identification information of a PDU session associated with a multicast session, service data stream SDF identification information of a multicast service, and the like). It should be noted that the identification information of the multicast group may be used to uniquely identify one multicast group, and in the present application, the identification information of the multicast group may also be described as the identification information of the multicast group instead, which is not limited. The second information may directly indicate (indication)/notify (notification) to activate the multicast session, for example, the second information may carry an information element/indicator (indication)/notification (notification), which explicitly indicates to activate the multicast session. In another example, the second information may indirectly indicate to activate the multicast Session, for example, the second information may be used to indicate/notify multicast Session start/start, and the second information is MBS Session start/Session start or multicast broadcast service Session activation (MBS Session activation) or multicast Session activation (multicast Session activation), or the second information is used to indicate that the second user plane functional network element detects data of the multicast service, for example, the second information may also be multicast broadcast service Session activation (MBS Session activation) or multicast Session activation (multicast Session activation), or the second information may be used to indicate that the first terminal is in a Connection Management (CM) connection state, or the like. Or, the second information may be used to indicate that the data of the multicast service reaches the second user plane functional network element or the second user plane functional network element detects the data of the multicast service or the data of the multicast service to be transmitted.

S802: and the first session management functional network element receives the second information and adds the first terminal into a multicast group corresponding to the multicast session.

For example, the first session management function network element may interact with an access network device and other core network devices (e.g., one or more of the first access and mobility management function network element, the second access and mobility management function network element, the first session management function network element, the second session management function network element, and the like) to join the first terminal to a multicast group corresponding to the multicast session. Specifically, the process of the first session management function network element interacting with the access network device and other core network devices to add the first terminal to the multicast group corresponding to the multicast session may be described with reference to fig. 5, and is not described in detail.

Further, if the PDU session associated with the multicast session is in a deactivated state, the method shown in fig. 8 may further include:

s803: and the first session management function network element activates the PDU session related to the multicast session.

Illustratively, for a first terminal in a CM-CONNECTED state within a multicast group, if a PDU session of the first terminal is associated with the multicast session and the associated PDU session is in a deactivated state, the first session management function network element activates the associated PDU session. Or, for a first terminal in a CM-CONNECTED state in a multicast group, when an access network device corresponding to the first terminal (that is, the access network device having an RRC connection with the first terminal device) does not support a multicast function, if an associated PDU session is in a deactivated state, the first session management function network element activates the associated PDU session.

For a first terminal in a CM-IDLE state, a network side device (e.g., a first access and mobility management function network element) may send a paging message to the first terminal through group paging (or a paging mode facing to a single terminal), and after receiving the paging message, the first terminal initiates a service request procedure to trigger the first session management function network element to activate a PDU session associated with a multicast session.

In one possible design, activating the PDU session associated with the multicast session may be described with reference to fig. 5, and is not described in detail.

In yet another possible design, the activating of the associated PDU session by the first session management function network element may include: and when the first session management function network element receives the indication information of the first mobility and accessibility management network element, which indicates that the PDU session is activated, the first session management function network element activates the PDU session related to the multicast session. Such as: and the first session management function network element receives the second information for activating the multicast session, determines the PDU session associated with the multicast session, and sends N1N2Namf _ Communication _ N1N2message transmission (N1N 2Namf _ Communication _ N1N2message transfer) carrying the identification information of the PDU session to the first access and mobility management function network element corresponding to the PDU session, so that the first access and mobility management function network element determines that the PDU session associated with the multicast session needs to be activated according to the identification information of the PDU session associated with the multicast session. The first access and mobility management function network element sends an Nsmf PDU session update session management context Request (Nsmf _ PDU session _ update smcontext Request) to the first session management function network element, where the Nsmf _ PDU session _ update smcontext Request may contain indication information for activating a PDU session, and may include an operation type field, for example, for indicating that an operation type is set to user plane activation (operation type set to "UP activation"). And the first session management functional network element receives the Nsmf _ PDUSESS _ UpdateSMContext Request, and activates the PDU session related to the multicast session according to an operation type field contained in the Nsmf _ PDUSESS _ UpdateSMContext Request.

The method includes that a first session management function network element interacts with an access network device and other core network elements to add a first terminal to a multicast group corresponding to a multicast session and activate an execution sequence between associated PDU sessions, after the PDU session associated with the multicast session is activated, the first session management function network element interacts with the access network device and other core network elements to add the first terminal to the multicast group corresponding to the multicast session and add the first terminal to the multicast group, or interacts with the access network device and other core network elements to add the first terminal to the multicast group corresponding to the multicast session and activate the associated PDU session simultaneously. For example, in a possible design, after receiving the second information, the first session management function may perform S802 according to the second information, and further optionally, the first session management function network element performs S803 again. In another possible design, after receiving the second information, the first session management function may perform S803 according to the second information, and further optionally, the first session management function network element performs S802 again.

In the method shown in fig. 8, before S801, the first session management function network element may determine to deactivate the multicast session through S804 or S805:

s804: and the first session management function network element receives the first information from the second session management function network element and determines to deactivate the multicast session according to the first information.

The first information may be an MBS Session stop/MBS Session deactivation, where the first information is an explicit indication information directly indicating to deactivate the multicast Session, and for example, a service Provider (Content Provider) may send the first information (MBS Session stop/Session stop) indicating to deactivate the multicast Session to the second Session management function network element, and the second Session management function network element receives the first information and sends the first information to the first Session management function network element; alternatively, the first information may be information for indicating stop/deactivation of the multicast session; alternatively, the first information may be information indicating that the second user plane function network element does not detect the data of the multicast service. The first information may carry identification information of the multicast service, and the specific description of the first information may be described with reference to fig. 5, which is not described in detail.

Specifically, the process of the first session management function network element receiving the first information from the second session management function network element may be described with reference to the corresponding embodiments in fig. 11 to fig. 14a below.

Further, after the first session management function network element receives the first information from the second session management function network element, the method may further include: and the first session management function network element sends first information to the access network equipment, so that the access network equipment determines to deactivate the multicast session according to the first information, and releases air interface resources and the like allocated to the multicast session.

S805: and the first session management function network element receives the eighth information and determines to deactivate the multicast session according to the eighth information.

The eighth information may be used to indicate that the multicast session corresponding to the multicast service is deactivated. The eighth information may also be used to indicate a release notification to release the multicast session tunnel. In an example one, the eighth information may be an indication/notification, which directly indicates/notifies to deactivate the multicast session, and the eighth information may carry identification information of the multicast service; or the eighth information is information for deactivating the PDU session associated with the multicast session, and the eighth information may carry identification information of the PDU session associated with the multicast session. The eighth information may be sent to the first session management function network element by the access network device through the first access and mobility management function network element or the second access and mobility management function network element.

For example, the first session management function network element may receive the eighth information through the first access and mobility management function network element, or the first session management function network element receives the eighth information through the second session management function network element, for example, the access network device sends the eighth information to the second access and mobility management function network element, after receiving the eighth information, the second access and mobility management function network element forwards the eighth information to the second session management function network element, and the second session management function network element sends the eighth information to the first session management function network element. Specifically, the process of the first session management function network element receiving the eighth information may be described with reference to the following embodiments corresponding to fig. 9 and fig. 10.

Further, after the first session management function network element receives the eighth information from the second session management function network element, the method may further include: the first session management function network element sends the eighth information to the second session management function network element, so that the second session management function network element interacts with the second user plane function network element, and the second user plane function network element is triggered to cache the data of the multicast service, delete the information related to the multicast session (for example, context information related to the multicast session, a tunnel related to the multicast session (such as a multicast session tunnel)), and the like.

Further, after determining to deactivate the multicast session, the first session management function network element marks the multicast session as a deactivated state.

For example, the first session management function network element may set a multicast session state in the related information of the multicast service corresponding to the multicast session/multicast service to a deactivated/inactive/standby state, or set the related information of the multicast session to a deactivated state, or the like.

Further, in the method shown in fig. 8, in order to maintain normal transmission of data of the multicast service before the multicast session is successfully activated, the method may further include: the first session management function network element determines to send the data of the multicast service through the PDU session associated with the multicast session, informs the first user plane function network element to establish a channel between the first user plane function network element and the second user plane function network element, maps the data of the multicast service onto the PDU session, and transmits the data of the multicast service to the first terminal through the PDU session. Specifically, the process may include:

the first session management function network element sends an N16 message to the second session management function network element, where the N16 message may be used to establish a channel (or referred to as a tunnel) for transmitting data of the multicast service between the second user plane function network element and the first user plane function network element, and the N16 message may include tunnel information of the first user plane function network element. The second session management function network element receives the N16 message, and sends a session update request (e.g., an N4 session update request) carrying the tunnel information of the first user plane function network element to the second user plane function network element. The second user plane functional network element receives the session update request, correspondingly stores the tunnel information of the first user plane functional network element and the identification information of the multicast service, establishes a channel for transmitting data of the multicast service between the second user plane functional network element and the first user plane functional network element, and sends a session update response (for example, an N4 session update response) to the second session management functional network element. And the second session management functional network element receives the session update response of the second user plane functional network element and sends a response of the N16 message carrying the identification information of the multicast service to the first session management functional network element. After receiving the response of the N16 message, the first session management function network element sends, to the first user plane function network element, the identification information of the multicast service and the QFI of the unicast QoS stream mapped by the multicast QoS stream according to the mapping relationship between the multicast QoS stream corresponding to the multicast service and the unicast QoS stream, so that the first user plane function network element correspondingly stores the identification information of the multicast service and the QFI of the unicast QoS stream mapped by the multicast QoS stream, maps the data of the multicast service into a PDU session, and transmits the data of the multicast service in the manner of the unicast QoS stream.

It should be understood that the embodiment of the present application does not limit the naming of the N16 message, and alternatively, the N16 message may also be referred to as an N16mb message or other names, without limitation.

Further, after mapping the data of the multicast service onto the PDU session, the method may further include: the first session management function network element sends third information to the first user plane function network element, where the third information may be used to indicate to detect data of a multicast service sent by the second user plane function network element or to indicate to send a notification to the first session management function network element when the data of the multicast service reaches the first user plane function network element, so that the first user plane function network element sends fourth information to the first session management function network element when detecting that the data of the multicast service reaches the first user plane function network element, so that the first session management function network element activates a multicast session according to the fourth information.

It should be noted that the third information may be carried in a session update request and sent to the first user plane function network element in a process that the first session management function network element performs session update (for example, N4 session update) with the first user plane function network element.

Optionally, if the first session management function network element in the method shown in fig. 8 determines to transmit the data of the multicast service through the PDU session, in order to save transmission resources, after the first terminal is rejoined to the multicast group corresponding to the multicast session, the method may further include: the first session management functional network element releases resources for transmitting data of the multicast service through the PDU session, for example, the access network device is triggered to release air interface resources for transmitting data of the multicast service corresponding to the PDU session, a channel for transmitting data of the multicast service between the first user plane functional network element and the second user plane functional network element is released, and a PDR for identifying data of the multicast service in the first user plane functional network element is released.

Based on the method shown in fig. 8, when the multicast session is in the deactivated state, after receiving the second information for activating the multicast session, the first session management function network element activates, for the UE in the CM-CONNECTED state in the multicast group, the associated PDU session if the associated PDU session is in the deactivated state; for the UE in the CM-IDLE state, the network side device may first perform group paging or paging for a single UE, and after receiving the paging message, the UE initiates a service request procedure to activate a PDU session associated with the multicast session. After the PDU session associated with the multicast session is activated, the first session management functional network element interacts with the access network device and other core network elements to add the first terminal to the multicast group corresponding to the multicast session, or the first session management functional network element interacts with the access network device and other core network elements to add the first terminal to the multicast group corresponding to the multicast session, and then activates the associated PDU session, or the first session management functional network element interacts with the access network device and other core network elements to add the first terminal to the multicast group corresponding to the multicast session and activates the associated PDU session simultaneously, which is not limited. Optionally, in a case that the data of the multicast service is mapped to the PDU session, after the multicast session is activated, the resource for transmitting the data of the multicast service through the PDU session is released, so that the multicast session can be activated/deactivated flexibly.

With reference to the 5G system shown in fig. 3a, the method shown in fig. 5 is performed on the access network device by taking an example that the first terminal is a UE, the access network device is a RAN, the first session management function network element is a first SMF, the second session management function network element is an MB-SMF/second SMF, the first user plane function network element is an UPF, the second user plane function network element is an MB-UPF, and the access and mobility management function network element is an AMF. It should be noted that, in the present application, the UPF may be integrated with the MB-UPF, and the integrated UPF may have the functions of both the UPF and the MB-UPF described in the present application, or the UPF and the MB-UPF may be deployed independently, without limitation. In the application, the SMF may be integrated with the MB-SMF, and the integrated SMF may have the functions of the SMF and the MB-SMF described in the application, or the SMF and the MB-SMF are independently deployed without limitation. In the method shown in fig. 8, the first Session management function network element receives the eighth information from the RAN, and the first Session management function network element marks that the multicast Session is deactivated, and triggers the RAN and the MB-UPF to deactivate the multicast Session, and subsequently, after receiving the second information (MBs Session start/Session start), the process of activating/restarting the multicast Session again is described in detail.

In this embodiment, the second information may include multicast broadcast service session activation (MBS session activation) or multicast session activation (multicast session activation).

Fig. 9 is a flowchart of a communication method according to an embodiment of the present application, and as shown in fig. 9, the method may include:

s901: and establishing a multicast session corresponding to the multicast service, and adding the UE into a multicast group corresponding to the multicast service.

For example, the UE joins the multicast session corresponding to the multicast service through the PDU session, and the process is as described above and is not described in detail.

S902a: the RAN executes AN AN release process, when the AN release process is executed, the first AMF determines that the UE enters a CM idle state, and the first AMF sends a notice that the UE enters the CM idle state to the first SMF. Accordingly, the first SMF receives a notification that the UE enters a CM idle state. It should be noted here that the RAN performs AN release procedure, and if the PDU session of the UE is associated with the multicast session and the multicast session is in AN active state, the AN release is not performed.

The first AMF may be an AMF corresponding to a PDU session of the first terminal (i.e., the first access and mobility management function network element described above).

For example, the first SMF may subscribe to the notification that the UE enters the CM idle state from the first AMF, for example, when the first SMF finds that the UE joins the multicast group through a control plane message or a user plane notification message of a certain PDU session of the UE, the first SMF may subscribe to the notification that the UE corresponding to the PDU session enters the CM idle state from the first AMF. Optionally, the first SMF may subscribe to the first AMF through the Namf _ EventExposure service to notify that the UE enters the idle state, and when the UE enters the CM idle state, the first AMF may send a notification that the UE enters the CM idle state to the first SMF, for example, the first AMF may send the notification that the UE enters the CM idle state to the first SMF through a return uniform resource identifier (call-back URI) of the first SMF when subscribing thereto.

S902b: the RAN determines to deactivate the multicast session and sends eighth information to the first SMF. Accordingly, the first SMF receives the eighth information.

The eighth information may be used to indicate that the multicast session corresponding to the multicast service is deactivated.

For example, if the duration that the RAN does not receive the data of the multicast service on the multicast session is greater than the preset duration, the RAN determines to deactivate the multicast session of the multicast service. Or, if there is no UE receiving the data of the multicast service in the UEs served by the RAN, the RAN determines to deactivate the multicast session of the multicast service.

The RAN may send, to the first SMF, eighth information through the first AMF or the second AMF, where the eighth information may be sent to the first AMF or the second AMF, and the eighth information is used to indicate that a multicast session corresponding to the multicast service is deactivated, and the eighth information may be carried in the N2 message. After receiving the eighth information, the first AMF locates to the corresponding first SMF according to the eighth information (e.g. an ID of a PDU session associated with the multicast session, or an SM context ID) carried in the N2 message, and may send the eighth information to the first SMF, where the eighth information may be carried in the N11 message. Or after receiving the eighth information, the second AMF sends the eighth information to the second SMF, and the second SMF locates the corresponding first SMF according to the eighth information (such as an ID of a PDU session associated with the multicast session, or an SM context ID) carried in the N2 message, and may send the eighth information to the first SMF, where the eighth information may be carried in the N11 message.

The eighth information may be an indication (indication) carried in the N2 message or a cause value (cause) for sending the N2 message, where the cause value indicates that the reason for triggering the sending of the N2 message is due to the multicast session deactivation. The N2 message may be a new type of N2 message or may be a UE-related N2 message, such as an N2 message related to a PDU session associated with a multicast session that is currently active. The N2 message may carry an ID of the PDU session associated with the multicast session. In addition, optionally, the N2 message may also carry identification information of a multicast service corresponding to the deactivated multicast session. Similarly, the eighth information may be an indication carried in the N11 message or a cause value for sending the N11 message, where the cause value indicates that the cause for triggering the sending of the N11 message is due to the multicast session deactivation, and the N11 message may be a new type of N11 message, or may be an N11 message related to a PDU session associated with the multicast session, such as a PDU session context update Request (N first SMF _ PDU _ update _ smcontext Request).

S902c: the RAN performs AN release procedure, such as: the RAN sends an N2 UE Context Release Complete message carrying the eighth information to the first AMF, the first AMF receives the N2 UE Context Release Complete (N2 UE Context Release Complete) message, sends the eighth information to the first SMF according to the eighth information, and correspondingly, the first SMF receives the eighth information.

For example, the first AMF may send an Nsmf SMF _ PDU _ update smcontext Request carrying eighth information to the first SMF, where the eighth information may be used to indicate to deactivate a PDU session, that is, indirectly indicate to deactivate a multicast session, where the PDU session is associated with the multicast session.

Further, after determining that the multicast session is deactivated or the PDU session associated with the multicast session is deactivated, the RAN releases the air interface resource allocated to the multicast session, and optionally, the RAN also deletes/removes/releases the context of the multicast session stored in the RAN. Alternatively, if the context of the multicast session is released, the RAN may determine to release the transport tunnel (or referred to as a multicast session tunnel) corresponding to the multicast session between the RAN and the MB-UPF.

Further, if the RAN determines to release the multicast session tunnel between the RAN and the MB-UPF, the eighth information and the eighth information may also carry a release notification/indication for releasing the multicast session tunnel, which is used to indicate/notify to release the multicast session tunnel.

S903: the first SMF determines to deactivate the multicast session and marks the multicast session as a deactivated state.

Illustratively, when the first SMF receives a notification sent by the first AMF to instruct the UE to enter a CM idle state, it determines to deactivate the multicast session, and the UE is a UE joining the multicast group. Or, when the first SMF receives eighth information for deactivating the multicast session, which is sent by the RAN, it determines to deactivate the multicast session. Or, when the first SMF receives the N first SMF _ PDU usage _ update smcontext Request carrying the PDU session deactivation, the first SMF determines to deactivate the multicast session according to the carried cell for deactivating the PDU session and the association between the PDU session and the multicast session.

S904: the first SMF sends an N16 message to the MB-SMF. Accordingly, the MB-SMF receives the N16 message.

The N16 message may be used to notify the MB-SMF to deactivate the multicast session, for example, the N16 message may be an existing N16 message, the N16 message may carry a notification/indication to deactivate the multicast session, and the notification/indication to deactivate the multicast session may be carried in the N16 message as a cell, for example, the cell may be an indication (indication)/notification (notification), or may be a cause value, that is, the reason for sending the N16 message is the notification/indication to deactivate the multicast session, and the like. Alternatively, the notification/indication to deactivate the multicast session may be sent to the MB-SMF as a separate signaling, such as a special N16 message to notify/indicate/request to deactivate the multicast session.

Optionally, if the eighth information received by the first SMF further carries a release notification/instruction for releasing the multicast session tunnel, the N16 message sent by the first SMF to the MB-SMF further carries a release notification/instruction for releasing the multicast session tunnel, and indicates/notifies to release the multicast session tunnel.

S905: the MB-SMF performs session update (e.g., N4 session update) with the MB-UPF.

Illustratively, the MB-SMF sends an N4 session update request to the MB-UPF, where the N4 session update request may carry identification information of the multicast service. Optionally, the N4 session update request further carries a notification/indication indicating that the MB-UPF caches the data of the multicast service, and optionally, if the MB-SMF does not notify the MB-UPF of caching the data of the multicast service, the MB-SMF may also cache the data of the multicast service; optionally, the N4 session update request may also be used to instruct/inform the MB-UPF to inform the MB-SMF when data of the multicast service arrives at the MB-UPF.

Optionally, when the N16 message carries a release notification for releasing the multicast session tunnel, the N4 session update request may also carry a release notification for releasing the multicast session tunnel. And the MB-UPF receives the release notice of the multicast session tunnel, and removes tunnel information related to the multicast session tunnel, such as tunnel endpoint identification information of a RAN side of the multicast session tunnel between the MB-UPF and the RAN. Thereafter, the MB-UPF sends an N4 session update response to the MB-SMF.

It should be noted that the notification may be carried in the N4 session update request as a cell, alternatively, may also be carried in a special N4 message, and is not limited.

S906: the MB-SMF sends a response to the N16 message to the first SMF. Accordingly, the first SMF receives a response to the N16 message.

S901 to S906 are related processes for deactivating a multicast session, and further, when data of a multicast service is retransmitted, to ensure transmission of the multicast service, the multicast session needs to be activated, and the process of activating the multicast session may refer to the following:

s907a: the AS/CP determines to start the multicast session and transmits the data of the multicast service, and the AS/CP sends a notification of starting the multicast session (MBS session start) to the MB-SMF through the NEF or directly. Accordingly, the MB-SMF receives a notification to start a multicast session.

Illustratively, the AS/CP may send a notification of starting a multicast session (MBs session start) and identification information of a multicast service corresponding to the multicast session that needs to be started, to the MB-SMF.

In the embodiment of the present application, the content indicated by starting the multicast session, the multicast broadcast service session activation (MBS session activation) or the multicast session activation (multicast session activation) is the same, and these descriptions may be used alternatively, without limitation.

S907b: and the MB-UPF detects that the data of the multicast service arrives at the MB-UPF and sends a notice of the data arrival of the multicast service to the MB-SMF. Accordingly, the MB-SMF receives the notification of the data arrival of the multicast service.

For example, the MB-UPF may send a user plane notification message to the MB-SMF, such as an N4 message, where the N4 message may carry a notification of data arrival of the multicast service and identification information of the multicast service. Optionally, the notification of the data arrival of the multicast service may be carried in the N4 message as an information element, where the information element may be an indication or a notification or may be a cause value, and the cause value may be used to indicate that the reason for sending the N4 message is the notification of the data arrival of the multicast service; alternatively, the notification of the data arrival of the multicast service may be sent as a proprietary message from the MB-UPF to the MB-SMF, which may be a proprietary N4 message.

It should be noted that S907a and S907b may be executed alternatively, and are not limited.

S908: the MB-SMF sends the second message to the first SMF. Accordingly, the first SMF receives the second information.

The second information may be used to indicate that data of the multicast service is to be transmitted, where the second information is MBS session start, and the second information may carry identification information of the multicast service, identification information or identification information of a multicast group (for example, one or more of TMGI, identification of the multicast service, a multicast address, a multicast IP address, identification of the multicast group, identification of the multicast session, context information of the multicast session, address information of the multicast service, identification information of a PDU session associated with the multicast session, and service data stream SDF identification information of the multicast service), and other information, without limitation. The identification information or identification information of the multicast group may be the same as the identification information of the multicast service, and is not limited.

For example, the MB-SMF may send an N16 message to the first SMF, where the N16 message carries the second information. The N16 message may carry identification information of the multicast service, the N16 message may carry a notification of data arrival of the multicast service or a notification that a multicast session needs to be started as a cell, where the notification of data arrival of the multicast service or the notification that a multicast session needs to be started may be an indication (indication), or the notification of data arrival of the multicast service or the notification that a multicast session needs to be started may also be a cause value, which is used to indicate that a reason for sending the N16 message is the notification of data arrival of the multicast service or the notification that a multicast session needs to be started. Optionally, the N16 message may also be a special N16 message, which is used specifically to indicate the data arrival of the multicast service or the start of the multicast session.

For example, after receiving the control plane message or the user plane notification message, the MB-SMF determines a first SMF to join in the multicast service according to the identification information of the multicast service carried in the control plane message or the user plane notification message, and sends second information to the determined first SMF.

Optionally, if the MB-SMF finds that the multicast session tunnel is already released when the multicast session is deactivated, the MB-SMF requests to establish the multicast session tunnel between the RAN and the MB-UPF. Optionally, the information requesting to establish the multicast session tunnel between the RAN and the MB-UPF may be an indication, a request (request), or a notification. Without limitation. Information requesting establishment of a multicast session tunnel between the RAN and the MB-UPF may be carried in the second information.

S909: and the first SMF determines that the PDU session associated with the multicast session exists according to the identification information of the multicast service carried by the second information, and sends N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer) to the first AMF corresponding to the PDU session. Accordingly, the first AMF receives the N1N2 messaging.

The determination that the PDU session associated with the multicast session exists by the first SMF may refer to the description in S501, which is not repeated herein.

The N1N2 message transmission may carry UE identification information, PDU session identification information, an N1 container (including an SM message sent to the UE), multicast group identification information or identification information, and N2 SM information, etc. The N2 SM information may include related information of the multicast service, where the related information of the multicast service is used to trigger the RAN to allocate an empty resource for the multicast session, and rejoin the UE to the multicast group corresponding to the multicast service, for example, the related information of the multicast service may include identification information of the multicast service, and may also include QFI of the multicast QoS stream, qoS parameter information corresponding to QFI of the multicast QoS stream, information of a unicast QoS stream corresponding to the multicast QoS stream, a request or indication for establishing a multicast session tunnel, and the like, and the information of the unicast QoS stream may include QFI of the unicast QoS stream and QoS parameter information corresponding to the unicast QoS stream.

Further, if the UE is in a CM-CONNECTED state (CM-CONNECTED), and if the associated PDU session is in a deactivated state, then 910 may be executed first and then 914 may be executed, or 914 may be executed first and then 910 may be executed, or 910 and 914 may be executed simultaneously, which is not limited. If the UE is in a CM IDLE state (CM-IDLE), 911-913 may be performed to activate the associated PDU session first, and then 914 may be performed, or 911-913 may be performed to return to a connected state (for example, the associated PDU session is not activated at this time), then S914 may be performed, and then the associated PDU session is activated, or the associated PDU session is activated simultaneously with 914, which is not limited.

S910: if the UE is in the CM-CONNECTED state, the first SMF activates the PDU session associated with the multicast session (e.g., continues to perform the service request procedure to activate the associated PDU session).

S911: after receiving the N1N2Message Transfer (naf _ Communication _ N1N2Message Transfer) in step S909, the first AMF triggers the first AMF to send a paging Message to the RAN in the registration area of the first terminal. Accordingly, the RAN receives the paging message.

The paging message may be used to page a single UE, the paging message may include identification information of the UE, or the paging message may be a group paging message, the paging message may be used to page a plurality of UEs in a CM-IDLE state in a multicast group, and the paging message may include identification information of a multicast service or identification information of the multicast group (e.g., TMGI of the multicast group, etc.). Illustratively, if the N1N2message delivery carries the identification information of the multicast group, the first AMF is triggered to send a paging message to the RAN in the registration area of the first terminal. And if the N1N2message transmission does not carry the identification information of the multicast group, triggering the first AMF to send a paging message aiming at the first terminal to the RAN in the registration area of the first terminal.

S912: and the RAN sends a paging message to the UE according to the identification information of the UE or the identification information of the multicast group. Accordingly, the UE receives the paging message sent by the RAN.

S913: and after receiving the paging message, the UE executes a service request flow and activates the PDU session associated with the multicast session.

For example, the process of the UE performing the service request procedure may refer to the prior art, and is not described in detail.

S914: the first SMF joins the UE to the multicast group by interacting with the access network device (e.g., RAN) and other core network elements (e.g., first AMF, MB-SMF, etc.).

Illustratively, joining a UE to a multicast group may include: when the multicast service is transmitted or distributed through the multicast session, the first SMF informs the RAN of distributing the air interface resource related to the multicast session for the UE through a signaling related to the UE, and the RAN adds the UE into the multicast group. Optionally, the base station may further interact with one or more network elements of AMF, SMF, MB-SMF, and MB-UPF to establish a multicast session tunnel between the base station and the MB-UPF.

When the multicast service is transmitted or distributed through the PDU session associated with the UE, the first SMF informs the RAN and the first user plane network element of allocating resources for transmitting the QoS stream related to the multicast service corresponding to the multicast session, and establishes a tunnel and the like between the first user plane network element and the second user plane network element.

Based on the method shown in fig. 9, the first SMF receives a message (or first information (e.g., multicast session stop)) that the MB-SMF deactivated the multicast session, marking the multicast session state as deactivated. After receiving a message of starting/starting a multicast session of an MB-SMF or activating a multicast session, for a UE in a CM-CONNECTED state in a multicast group, if an associated PDU session is in a deactivated state, the first SMF activates the associated PDU session, it should be noted that after the PDU session associated with the multicast session is activated, the first SMF may add the UE to the multicast group by interacting with the RAN and other core network elements, or the first SMF may add the UE to the multicast group by interacting with the RAN and other core network elements, first add the UE to the multicast group, and then activate the associated PDU session, or the first SMF may add the UE to the multicast group and activate the associated PDU session at the same time by interacting with the RAN and other core network elements, without limitation. For the UE in the CM-IDLE state, the network-side device may first go through group paging (group paging) or paging towards a single UE. And after receiving the paging message, the UE initiates a service request flow to activate the PDU session associated with the multicast session. It should be noted that, after the PDU session associated with the multicast session is activated, the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, or the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, and then activate the associated PDU session, or the first SMF may join the UE to the multicast group and activate the associated PDU session at the same time by interacting with the RAN and with other core network elements, which is not limited.

In the following, with reference to the 5G system shown in fig. 3a, by taking the first terminal as UE, the access network device as RAN, the first session management function network element as first SMF/SMF, the second session management function network element as MB-SMF, the first user plane function network element as UPF, the second user plane function network element as MB-UPF, and the access and mobility management function network element as AMF, for example, in the method shown in fig. 8, the first session management function network element receives the eighth information, the state of the multicast session marked by the first session management function network element according to the eighth information is deactivated, maps the data of the multicast service to the PDU session, and describes in detail the process of transmitting the data of the multicast service through the PDU session. It should be noted that, in the present application, the UPF may be integrated with the MB-UPF, and the integrated UPF may have the functions of both the UPF and the MB-UPF described in the present application, or the UPF and the MB-UPF may be deployed independently, without limitation. In this application, the first SMF may be integrated with the MB-SMF, and the integrated SMF may have the functions of the first SMF and the MB-SMF described in this application, or the first SMF and the MB-SMF may be deployed independently, without limitation.

Fig. 10 is a flowchart of a communication method according to an embodiment of the present application, and as shown in fig. 10, the communication method may include:

s1001: and establishing a multicast session corresponding to the multicast service, and adding the UE into a multicast group corresponding to the multicast service.

S1001 may refer to S901, which is not described in detail.

S1002a: the RAN executes AN AN release flow, when the AN release flow is executed, the first AMF determines that the UE enters a CM idle state, and the first AMF sends a notice that the UE enters the CM idle state to the first SMF. Accordingly, the first SMF receives a notification that the UE enters a CM idle state.

S1002a may refer to S902a, which is not described in detail.

S1002b: the RAN determines to deactivate the multicast session and sends eighth information to the first SMF via the first AMF. Accordingly, the first SMF receives the eighth information.

S1002b can be described with reference to S902b, and is not described in detail.

S1002c: the RAN executes AN AN release flow, sends a UE context release completion message carrying eighth information to the first AMF, the first AMF receives the UE context release completion message, sends the eighth information to the first SMF according to the eighth information, and correspondingly, the first SMF receives the eighth information.

S1002c may refer to S902c, which is not described herein.

S1003: the first SMF determines to deactivate the multicast session and marks the multicast session as a deactivated state.

S1003 can refer to S903, and is not described in detail.

Next, the first SMF maps the data of the multicast service to the PDU session, and transmits the data of the multicast service through the PDU session, where the PDU session may be a PDU session associated with the multicast session, or may not be a PDU session associated with the multicast session, without limitation. Specifically, the process may refer to S1004 to S1007 described below.

S1004: the first SMF sends an N16 message to the MB-SMF. Accordingly, the MB-SMF receives the N16 message.

The N16 message may be used to notify the MB-SMF to deactivate the multicast session, and optionally, the N16 message may include information of a tunnel of the UPF and a notification of deactivation of the multicast session. Optionally, the notification of deactivating the multicast session may be included in the N16 message as an information element, for example, the information element may be an indication, or may be a cause value, that is, the reason for sending the N16 message is the notification of deactivating the multicast session, or the like; the notification to deactivate a multicast session may also be a separate signaling, e.g. a dedicated N16 message, dedicated to the notification to deactivate a multicast session.

S1005: and the MB-SMF and the MB-UPF carry out N4 session update, and a channel for transmitting data of the multicast service between the MB-SMF and the UPF is established.

For example, the MB-SMF sends an N4 session update request to the MB-UPF, and optionally, the N4 session update request carries the tunnel information of the UPF described in S1005. And the MB-UPF receives the tunnel information of the UPF, establishes a channel/tunnel for transmitting the data of the multicast service with the UPF, and sends an N4 session update response to the MB-SMF.

S1006: the MB-SMF sends a response to the N16 message to the first SMF. Accordingly, the first SMF receives a response to the N16 message.

S1007: and the first SMF and the UPF perform N4 session update, and map the multicast QoS stream of the multicast service into a PDU session tunnel of the PDU session for transmission in a mode of unicast QoS stream.

Illustratively, after receiving the response of the N16 message, the first SMF configures the UPF according to the information of the multicast service and the mapping relationship between the multicast QoS stream and the unicast QoS stream included in the multicast service. Specifically, the first SMF sends the information of the multicast service and the QFI of the unicast QoS stream mapped by the multicast QoS stream to the UPF, so as to map the multicast QoS stream into a PDU session tunnel of the PDU session for transmission in a unicast QoS stream manner, where the information of the multicast service may include identification information of the multicast service, and may further include a PDR and the like, and for the filtered data of the multicast service, the UPF maps the data of the multicast service into the PDU session according to a mapping relationship between the QFI of the multicast QoS stream and the QFI of the unicast QoS stream for transmission in a unicast QoS stream manner.

Further, the first SMF may further send third information to the UPF, where the third information is used to indicate to monitor data of the multicast service from the MB-SMF, and send fourth information to the first SMF when the data of the multicast service from the MB-SMF reaches the UPF, so that the first SMF determines to activate the multicast session according to the fourth information.

The third information may be sent to the UPF when the first SMF and the UPF perform N4 session update, for example, the third information is carried in the session update request and sent to the UPF, and the third information may also be sent to the UPF before or after the first SMF and the UPF perform N4 session update, which is not limited.

The foregoing steps 1001 to S1007 are related processes for deactivating a multicast session and mapping data of a multicast service to a related process of a PDU session, and further, when data of the multicast service is transmitted again by using a multicast mode, to ensure transmission of the multicast service, a multicast session needs to be activated, and the process of activating the multicast session may refer to the following steps:

s1008: the AS/CP determines to start the multicast Session, that is, the data of the multicast service is to be transmitted, and sends a notification (MBS Session start/Session start) for starting the multicast Session, or multicast broadcast service Session activation (MBS Session activation) or multicast Session activation (multicast Session activation) to the MB-SMF through the NEF or directly. Accordingly, the MB-SMF receives a notification to start a multicast session.

S1009: the MB-SMF sends second information, which may include identification information or identification information of the multicast group, to the first SMF. Accordingly, the first SMF receives the second information.

S1010: and if the UPF receives the third information sent by the first SMF, the UPF sends a notification of the data arrival of the multicast service or detects fourth information of the data of the multicast service to the first SMF after detecting that the data of the multicast service arrives at the UPF. Accordingly, the first SMF receives the fourth information.

In fig. 10, S1008 and S1009 may be executed, or S1010 may be executed, without limitation.

S1011: the first SMF determines, according to the identification information of the multicast service carried in the second information or the fourth information, that a PDU session associated with the multicast session exists, and sends an N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer), which may include identification information or identifier information of the multicast group, to the first AMF corresponding to the PDU session. Accordingly, the first AMF receives the N1N2 messaging.

If the UE is in the CM connected state and the PDU session is in the deactivated state, perform S1012 and then perform S1016, or perform S1016 first and then perform S1012, or perform S1016 and S1012 simultaneously, which is not limited. For the UE in CM idle state, first performing S1013 to S1015 to activate the associated PDU session, and then performing S1016, or first performing S1013 to S1015 to return to connected state (for example, at this time, the associated PDU session is not activated), then performing S1016, and then performing S1016, or activating the associated PDU session and joining the UE to the multicast group may be performed simultaneously, without limitation.

S1012: if the UE is in the CM-CONNECTED state, the first SMF continues to execute the service request process to activate the associated PDU session.

S1013: after receiving the N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer), the first AMF is triggered to send a paging Message to the RAN in the registration area of the UE. Accordingly, the RAN receives the paging message.

Specifically, step S1013 may be described with reference to step S911, which is not described in detail.

S1014: and the RAN sends a paging message to the UE according to the identification information of the UE or the identification information of the multicast group. Accordingly, the UE receives the paging message sent by the RAN.

S1015, after receiving the paging message, the UE executes the service request flow to activate the PDU session associated with the multicast session.

S1016: and the first SMF interacts with the access network equipment and other core network elements to join the UE into the multicast group.

Specifically, step S1016 can be described with reference to fig. 5, and is not described in detail.

Based on the method shown in fig. 10, the first SMF receives a message (or first information (e.g., multicast session stop)) that the MB-SMF deactivated the multicast session, marking the multicast session state as deactivated. After receiving a message of starting/starting a multicast session of an MB-SMF or activating a multicast session, for a UE in a CM-CONNECTED state in a multicast group, if an associated PDU session is in a deactivated state, the first SMF activates the associated PDU session, it should be noted that, after the PDU session associated with the multicast session is activated, the first SMF may join the UE into the multicast group by interacting with the RAN and with other core network elements, or the first SMF may join the UE into the multicast group by interacting with the RAN and with other core network elements, and then activates the associated PDU session, or the first SMF may join the UE into the multicast group and activate the associated PDU session at the same time by interacting with the RAN and with other core network elements, without limitation. For the UE in the CM-IDLE state, the network side device may first go through group paging or paging towards a single UE. And after receiving the paging message, the UE initiates a service request flow to activate the PDU session associated with the multicast session. It should be noted that, after the PDU session associated with the multicast session is activated, the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, or the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, and then activate the associated PDU session, or the first SMF may join the UE to the multicast group and activate the associated PDU session at the same time by interacting with the RAN and with other core network elements, which is not limited.

In the following, with reference to the 5G system shown in fig. 3a, a detailed description is given to a process in which, in the method shown in fig. 8, the first Session management functional network element receives first information (MBs Session stop/Session stop) from the second Session management functional network element, marks a state of a multicast Session as a deactivated state according to the first information, and subsequently activates/restarts the multicast Session after receiving second information (MBs Session start/Session start), by taking the first terminal as a UE, the access network device as a RAN, the first Session management functional network element as a first SMF/SMF, the second Session management functional network element as a MB-SMF, the first user plane functional network element as a UPF, and the second user plane functional network element as an MB-UPF, and the access and mobility management functional network element as an AMF, for example. It should be noted that, in the present application, the UPF may be integrated with the MB-UPF, and the integrated UPF may have the functions of both the UPF and the MB-UPF described in the present application, or the UPF and the MB-UPF may be deployed independently, without limitation. In this application, the first SMF may be integrated with the MB-SMF, and the integrated SMF may have the functions of the SMF described in this application, or may have the functions of the MB-SMF, or the SMF and the MB-SMF may be deployed independently, without limitation.

In this embodiment of the application, the first information further includes multicast broadcast service session deactivation (MBS session deactivation) or multicast session deactivation (multicast session deactivation). The contents represented by multicast broadcast service session stop, multicast broadcast service session deactivation (MBS session deactivation) or multicast session deactivation (multicast session deactivation) are the same, and these descriptions can be used alternatively.

In this embodiment of the application, the second information may further include multicast broadcast service session activation (MBS session activation) or multicast session deactivation (multicast session activation). The contents expressed by multicast broadcast service session initiation, multicast broadcast service session activation (MBS session activation) or multicast session activation (multicast session activation) are the same, and these descriptions can be used alternatively.

Fig. 11 is a flowchart of a communication method according to an embodiment of the present application, and as shown in fig. 11, the communication method may include:

s1101: and establishing a multicast session corresponding to the multicast service, and adding the UE into a multicast group corresponding to the multicast service.

S1101 can be described with reference to S901, and is not repeated.

And executing an event A, an event B or an event C, receiving first information from the MB-SMF by the first SMF, determining to deactivate the multicast session according to the first information, and marking the multicast session as a deactivated state.

Wherein, the event a may include: 1a, the RAN determines to deactivate the multicast session, and sends eighth information for deactivating the multicast session to the first AMF (or a second AMF (not shown in fig. 11)). 2a, the first AMF (or the second AMF) receives the notification of the deactivation of the multicast session, and sends the notification of the deactivation of the multicast session to the MB-SMF. And 3a, the MB-SMF receives the notice of the deactivation of the multicast session and carries out N4 session update with the MB-UPF. 4a, the MB-SMF sends first information to the first SMF. Accordingly, the first SMF receives the first message from the MB-SMF.

The second AMF may be an AMF corresponding to the multicast group.

The process of determining to deactivate the multicast session by the RAN may be described with reference to S902b in fig. 9, and the process of performing session update on the MB-SMF and the MB-UPF in the event a may be described with reference to S905, which is not described in detail.

As shown in fig. 11, event B may include: 1b, the AS/CP sends first information (for example, a multicast Session stop/Session stop) to the MB-SMF through a network open function (NEF) or directly, where the first information includes identification information of a multicast service corresponding to a multicast Session that needs to be stopped (or deactivated).

2b, the MB-SMF receives the message of stopping the multicast session, the MB-SMF and the MB-UPF carry out N4 session update, and the MB-UPF is informed to deactivate the multicast session or stop the multicast session. Further, the MB-SMF may determine whether to release the multicast session tunnel, and if it is determined to release the multicast session tunnel, notify the MB-UPF to release the multicast session tunnel when performing N4 session update with the MB-UPF. The MB-SMF notifies/instructs the MB-UPF to cache the arrival notification/report of the next multicast session data.

3b, after receiving the message of stopping the multicast Session, the MB-SMF determines the first SMF joining the multicast service, and sends first information (e.g. multicast Session stop/Session stop)) to the first SMF, where the first information may be used to indicate that the multicast Session stops (e.g. MBs Session stop) or directly indicate that the multicast Session is deactivated. Optionally, if the MB-SMF determines to release the multicast session tunnel, the first information further includes a message for releasing the multicast session tunnel.

And 4b, the first SMF receives first information sent by the MB-SMF, the state mark (mark) of the multicast session is deactivated or set as is set according to the first information, whether the PDU session related to the multicast session service exists is determined according to the identification information of the multicast service, and if so, the first SMF sends N1N2 message transmission to the first AMF. The N1N2 messaging may include identification information of the UE, a PDU Session identifier, N2 SM information, and the like, and the N2 SM information may include the first information (e.g., multicast Session stop/Session stop) described in 3 b), which tells the RAN that a multicast Session corresponding to the multicast service needs to be stopped (or deactivated).

5b, the first AMF sends N2 message to RAN, and the N2 message can carry the first information. And after receiving the first information, the RAN releases the air interface resources allocated to the multicast session. Optionally, if the RAN further receives a release notification for releasing the multicast session tunnel, the RAN may also remove context information (for example, a multicast session context or a multicast group context or a multicast service context) corresponding to the multicast service stored in the RAN, remove information related to the multicast tunnel, release an air interface resource corresponding to the multicast session, and the like.

It should be noted here that when the multicast session is deactivated, the first SMF may deactivate the PDU session associated with the multicast session. Or, conversely, when the first SMF is to deactivate the associated PDU session, it finds that the PDU session is associated with the multicast session and the multicast session is in an active state, and then the first SMF does not deactivate the PDU session; conversely, when the multicast session is in a deactivated state or a released/deleted state, the PDU session may be deactivated.

It should be noted that the order of 2b and 3b to 5b is not limited, for example, 2b may be executed in parallel with 3b or 4b or 5 b; for another example, it may be performed in the order of 2b, 3b, 4b, 5 b; for another example, it may be performed in the order of 3b, 2b, 4b, 5 b; for example, the sequence may be 3b, 4b, 2b, and 5b, and is not limited.

As shown in fig. 11, event C may include: 1c, MB-UPF does not detect the data of the multicast service for a long time. 2c, the MB-UPF sends a message of not detecting the data of the multicast service to the MB-SMF, wherein the message contains the identification information of the multicast service of not detecting the data.

And 3c, the MB-SMF receives a message that the data of the multicast service is not detected, the MB-SMF sends a response message to the MB-UPF, and notifies the MB-UPF to deactivate the multicast session and cache the data of the multicast service, or sends a notification to the MB-SMF when the data of the multicast service reaches the MB-UPF. Further, the MB-SMF may determine whether to release the multicast session tunnel, and if it is determined to release the multicast session tunnel, may also notify the MB-UPF to release the multicast session tunnel.

4c, after receiving the message that the data of the multicast service is not detected, the MB-SMF determines a first SMF joining the multicast service, and sends first information to the first SMF, where the first information may be used to indicate that the data of the multicast service is not detected or directly indicate that the multicast session is deactivated. Optionally, if the MB-SMF determines to release the multicast session tunnel, the eighth information further includes a message of releasing the multicast session tunnel.

And 5c, the first SMF receives the first information sent by the MB-SMF, the state of the multicast session is marked as deactivated according to the first information, and whether a PDU session related to the multicast session service exists or not is determined according to the identification information of the multicast service, if so, the first SMF sends N1N2 message transmission to the first AMF. The N1N2 message transmission may include identification information of the UE, a PDU session identifier, N2 SM information, and the like, and the N2 SM information may include first information of S3b, which tells the RAN that a multicast session corresponding to the multicast service needs to be stopped (or deactivated).

6c, the first AMF sends an N2 message to the RAN, and the N2 message can carry the first information. And after receiving the first information, the RAN releases the air interface resources allocated to the multicast session. Optionally, if the RAN further receives a release notification for releasing the multicast session tunnel, the RAN may further remove the context of the multicast session corresponding to the multicast service stored in the RAN, release information related to the multicast session tunnel, and the like.

It should be noted that the order of 2c and 3c to 6c is not limited, for example, 2c may be executed in parallel with 3c, 4c, 5c, or 6 c; for another example, it may be performed in the order of 2c, 3c, 4c, 5c, 6 c; for another example, it may be performed in the order of 3c, 2c, 4c, 5c, 6 c; for example, the sequence may be 3c, 4c, 2c, 5c, and 6c, without limitation.

The foregoing steps are related processes for deactivating a multicast session, and further, when data of a multicast service is retransmitted, in order to ensure transmission of the multicast service, a multicast session needs to be activated, and the process of activating the multicast session may refer to the following steps:

s1102a: the AS/CP determines to start the multicast session, transmits the data of the multicast service, and sends a notification (e.g., MBS session start) for starting the multicast session to the MB-SMF through the NEF. Accordingly, the MB-SMF receives the notification to start the multicast session. The notification of starting the multicast session may alternatively be described as multicast broadcast service session activation (MBS session activation) or multicast session activation (multicast session activation).

S1102b: and the MB-UPF detects that the data of the multicast service arrives at the MB-UPF and sends a notice of the data arrival of the multicast service to the MB-SMF. Accordingly, the MB-SMF receives notification of data arrival of the multicast service.

In fig. 11, S1102a and S1102b may be executed either or both, and are not limited.

S1103: the MB-SMF sends second information, which may include identification information of the multicast group, to the first SMF corresponding to the PDU session associated with the multicast session. Accordingly, the first SMF receives the second information.

S1104: and the first SMF determines that a PDU session associated with the multicast session exists according to the identification information of the multicast service carried by the second information, and sends an N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer) to the AMF corresponding to the PDU session, wherein the Namf _ Communication _ N1N2Message Transfer may include identification information of the multicast group. Accordingly, the AMF receives the N1N2 messaging.

If the UE is in the CM connected state and the PDU session is in the deactivated state, S1105 may be executed first and then S1109 may be executed, or S1109 and then S1105 may be executed first, or S1105 and S1109 may be executed simultaneously, which is not limited. For the UE in CM idle state, 1106 to 1108 are executed to activate the associated PDU session first, and then 1109 is executed, or 1106 to 1108 may be executed to return to connected state first (for example, the associated PDU session is not activated at this time), and then S1109 is executed, or S1106 to S1108 and S1109 are executed simultaneously (that is, the associated PDU session is activated and the UE is added to the multicast group and executed simultaneously), which is not limited.

S1105: if the UE is in the CM-CONNECTED state, the first SMF continues to execute the service request process to activate the associated PDU session.

S1106: after receiving the N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer), the first AMF is triggered to send a paging Message to the RAN in the registration area of the UE. Accordingly, the RAN receives the paging message.

Specifically, step S1106 may be described with reference to step S911, which is not described in detail.

S1107: and the RAN sends a paging message to the UE according to the identification information of the UE or the identification information of the multicast group. Accordingly, the UE receives the paging message sent by the RAN.

S1108: and after receiving the paging message, the UE executes a service request flow and activates the PDU session associated with the multicast session.

Specifically, step S1107 can be described with reference to step S913, and is not described in detail.

S1109: and the first SMF interacts with the access network equipment and other core network elements to join the UE into the multicast group.

Specifically, step S1109 may be described in the embodiment corresponding to fig. 5, and is not described in detail.

Based on the method shown in fig. 11, the first SMF receives a message (or first information (e.g., multicast session stop)) that the MB-SMF deactivates the multicast session, marking the multicast session state as deactivated. After receiving a message of starting/starting a multicast session of an MB-SMF or activating a multicast session, for a UE in a CM-CONNECTED state in a multicast group, if an associated PDU session is in a deactivated state, the first SMF activates the associated PDU session, it should be noted that after the PDU session associated with the multicast session is activated, the first SMF may add the UE to the multicast group by interacting with the RAN and other core network elements, or the first SMF may add the UE to the multicast group by interacting with the RAN and other core network elements, first add the UE to the multicast group, and then activate the associated PDU session, or the first SMF may add the UE to the multicast group and activate the associated PDU session at the same time by interacting with the RAN and other core network elements, without limitation. For the UE in the CM-IDLE state, the network side device may first go through group paging or paging towards a single UE. And after receiving the paging message, the UE initiates a service request flow to activate the PDU session associated with the multicast session. It should be noted that, after the PDU session associated with the multicast session is activated, the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, or the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, and then activate the associated PDU session, or the first SMF may join the UE to the multicast group and activate the associated PDU session at the same time by interacting with the RAN and with other core network elements, which is not limited.

In the following, referring to the 5G system shown in fig. 3a, taking the first terminal as UE, the access network device as RAN, the first session management function network element as first SMF, the second session management function network element as MB-SMF, the first user plane function network element as UPF, the second user plane function network element as MB-UPF, and the access and mobility management function network element as AMF, for example, in the method shown in fig. 8, the first session management function network element receives the first information from the second session management function network element, marks the state of the multicast session as a deactivated state according to the first information, maps the data of the multicast service to the PDU session, transmits the data of the multicast service in a unicast manner through the PDU session, and subsequently, after receiving the second information (MBs session start), activates/restarts the multicast session in detail. In the following embodiments, the second information may also be multicast broadcast service session activation (MBS session activation) or multicast session activation (multicast session activation).

Fig. 12 is a flowchart of a communication method according to an embodiment of the present application, and as shown in fig. 12, the communication method may include:

s1201: and establishing a multicast session corresponding to the multicast service, and adding the UE into a multicast group corresponding to the multicast service.

S1201 can be described with reference to S901, and is not described in detail.

Next, in a possible implementation manner, event a is executed, the first SMF receives the first information from the MB-SMF, determines to deactivate the multicast session according to the first information, and marks the multicast session as a deactivated state, meanwhile, after the first SMF receives the first information from the MB-SMF, the data of the multicast service is mapped onto the PDU session, and the data of the multicast service is transmitted through the PDU session, where the PDU session may be a PDU session associated with the multicast session, or may not be a PDU session associated with the multicast session, and is not limited.

Specifically, the relevant process of the event a may refer to fig. 1a to 4a in fig. 11, and the process of the first SMF mapping the data of the multicast service onto the PDU session may refer to S1004 to S1007 in fig. 10, which is not described again.

In yet another possible design, as shown in fig. 12, 1B, 3B to 5B of the above event B are performed, the first SMF receives the first information from the MB-SMF, determines to deactivate the multicast session according to the first information, and marks the multicast session as a deactivated state, and meanwhile, after 3B and before 4B, the first SMF maps the data of the multicast service onto the PDU session, and transmits the data of the multicast service through the PDU session, which may be a PDU session associated with the multicast session or not, without limitation.

Specifically, the process of mapping the data of the multicast service to the PDU session by the first SMF may refer to the foregoing S1005 to S1008 in fig. 10, which is not described again.

In another possible implementation manner, as shown in fig. 12, 1C-2C, 4C-6C in the event C are executed, the first SMF receives the first information from the MB-SMF, determines to deactivate the multicast session according to the first information, and marks the multicast session as a deactivated state, meanwhile, after 4C and before 5C, the first SMF maps data of the multicast service onto a PDU session, and transmits the data of the multicast service through the PDU session, where the PDU session may be a PDU session associated with the multicast session or may not be a PDU session associated with the multicast session, which is not limited.

Specifically, the process of mapping the data of the multicast service onto the PDU session by the first SMF may refer to S1004 to S1007 in fig. 10, which is not described in detail.

Further, the first SMF may further send third information to the UPF, where the third information is used to indicate to monitor data of the multicast service from the MB-SMF, and send fourth information to the first SMF when the data of the multicast service from the MB-SMF reaches the UPF, so that the first session management function network element activates a multicast session according to the fourth information.

The third information may be sent to the UPF when the first SMF and the UPF perform N4 session update, or may be sent to the UPF before or after the first SMF and the UPF perform N4 session update, which is not limited.

The foregoing steps are related processes of deactivating a multicast session and mapping data of a multicast service to a PDU session, and further, when data of the multicast service is transmitted again in a multicast manner, to ensure multicast transmission of the multicast service, a multicast session needs to be activated, and the process of activating the multicast session may refer to the following steps:

s1202: the AS/CP determines to start the multicast session, namely, the data of the multicast service is to be transmitted, and the AS/CP sends a notification of starting the multicast session to the MB-SMF through the NEF or directly. Accordingly, the MB-SMF receives the notification to start the multicast session.

S1203: the MB-SMF sends second information to the first SMF, which may include identification information of the multicast group. Accordingly, the first SMF receives the second information.

S1204: and if the UPF receives the third information sent by the first SMF, the UPF sends a notification of the data arrival of the multicast service or detects fourth information of the data of the multicast service to the first SMF after detecting that the data of the multicast service arrives at the UPF. Accordingly, the first SMF receives the fourth message.

The method shown in fig. 12 may execute S1202 and S1203, or execute S1204, without limitation.

S1205: and the first SMF determines that a PDU session associated with the multicast session exists according to the identification information of the multicast service carried by the second information or the fourth information, and sends an N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer) to the AMF corresponding to the PDU session, where the N1N2Message Transfer may include identification information of the multicast group. Accordingly, the AMF receives the N1N2 messaging.

If the UE is in the CM connected state and the PDU session is in the deactivated state, then execute S1206 and then execute S1210, or execute S1210 and then execute S1206 first, or execute S1210 and S1206 simultaneously, which is not limited. For the UE in CM idle state, first, S1207 to S1209 are performed to activate the associated PDU session, and then S1210 is performed, or, first, S1207 to S1209 may be performed to return to connected state (for example, the associated PDU session is not activated at this time), then the associated PDU session is activated, and then S1210 is performed, or S1207 to S1209 may be performed while S1210 is performed (that is, the activation of the associated PDU session and the joining of the UE to the multicast group are performed simultaneously), which is not limited.

S1206: if the UE is in the CM-CONNECTED state, the first SMF continues to execute the service request process to activate the associated PDU session.

S1207: the first AMF receives the N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer), and triggers the first AMF to send a paging Message to the RAN in the registration area of the UE. Accordingly, the RAN receives the paging message.

S1208: and the RAN sends a paging message to the UE according to the identification information of the UE or the identification information of the multicast group. Accordingly, the UE receives the paging message sent by the RAN.

S1209: and after receiving the paging message, the UE executes a service request flow and activates the PDU session associated with the multicast session.

Specifically, step S1209 may be described with reference to step S913, and is not described in detail.

S1210: and the first SMF interacts with the access network and other core network elements to join the UE into the multicast group.

Specifically, step S1210 may be described with reference to the embodiment corresponding to fig. 5, and is not described in detail.

Based on the method shown in fig. 12, the first SMF receives a message (or first information (e.g., multicast session stop)) that the MB-SMF deactivated the multicast session, marking the multicast session state as deactivated. After receiving a message of starting/starting a multicast session of an MB-SMF or activating a multicast session, for a UE in a CM-CONNECTED state in a multicast group, if an associated PDU session is in a deactivated state, the first SMF activates the associated PDU session, it should be noted that, after the PDU session associated with the multicast session is activated, the first SMF may join the UE into the multicast group by interacting with the RAN and with other core network elements, or the first SMF may join the UE into the multicast group by interacting with the RAN and with other core network elements, and then activates the associated PDU session, or the first SMF may join the UE into the multicast group and activate the associated PDU session at the same time by interacting with the RAN and with other core network elements, without limitation. For the UE in the CM-IDLE state, the network side device may first go through group paging or paging towards a single UE. And after receiving the paging message, the UE initiates a service request flow to activate the PDU session associated with the multicast session. It should be noted that, after the PDU session associated with the multicast session is activated, the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, or the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, and then activate the associated PDU session, or the first SMF may join the UE to the multicast group and activate the associated PDU session at the same time by interacting with the RAN and with other core network elements, which is not limited.

In the following, with reference to the 5G system shown in fig. 3a, taking the first terminal as UE, the access network device as RAN, the first session management function network element as first SMF, the second session management function network element as MB-SMF, the first user plane function network element as UPF, the second user plane function network element as MB-UPF, and the access and mobility management function network element as AMF, the process that, in the method shown in fig. 8, the first session management function network element receives the first information from the second session management function network element, marks the state of the multicast session as a deactivated state according to the first information, deactivates the multicast session, and subsequently reactivates/restarts the multicast session after receiving the second information (MBs session start) is described in detail. In the following embodiments, the second information may also be multicast broadcast service session activation (MBS session activation) or multicast session activation (multicast session activation).

Fig. 13 is a flowchart of a communication method according to an embodiment of the present application, and as shown in fig. 13, the communication method may include:

s1301: and establishing a multicast session corresponding to the multicast service, and adding the UE into a multicast group corresponding to the multicast service.

S1301 may refer to S901, which is not described in detail.

And executing an event D or an event E, receiving first information from the MB-SMF by the first AMF or the second AMF through the RAN, determining to deactivate the multicast session according to the first information, and marking the multicast session as a deactivated state by the first SMF.

As shown in fig. 13, event D may include: 1d, AS/CP sends a message of multicast session stop (MBS session stop) to MB-SMF, wherein the message contains the identification information of the multicast service corresponding to the multicast session to be stopped (or deactivated).

The multicast session stop may be alternatively described as multicast broadcast service session deactivation (MBS session deactivation) or multicast session deactivation (multicast session deactivation).

And 2d, the MB-SMF receives the message of multicast session stop, the MB-SMF updates the N4 session with the MB-UPF, informs the MB-UPF of multicast session deactivation or multicast session stop, and indicates/informs the MB-UPF of report or informs the next arrival of multicast session data. Further, the MB-SMF may determine whether to release the multicast session tunnel, and if it is determined to release the multicast session tunnel, notify the MB-UPF to release the multicast session tunnel when performing N4 session update with the MB-UPF.

And after receiving the multicast session stop message, the MB-SMF sends first information to the second AMF, wherein the first information can carry the multicast session stop message and identification information of the multicast service and is used for indicating the multicast session stop or deactivating the multicast session. The first information is also used to indicate to release the multicast session tunnel if the MB-SMF determines to release the multicast session tunnel.

4d, the second AMF receives the first information and sends the first information to the RAN, for example, the first information is carried in the N2 message. And after receiving the first information, the RAN releases the air interface resources allocated to the multicast session. Optionally, if the RAN further receives a release notification for releasing the multicast session tunnel, the RAN may further remove the context of the multicast session corresponding to the multicast service stored in the RAN, release the related information of the multicast session tunnel, and the like.

5d, the RAN sends the first information to the first AMF.

And 6d, the first AMF receives the first information and sends the first information to the first SMF, the first SMF receives the first information, the multicast session is determined to be deactivated according to the first information, and the state of the multicast session is marked as deactivated.

It should be noted that the order of 2d and 3d to 6d is not limited, for example, 2d may be executed in parallel with 3d, 4d, 5, or 6 d; for another example, it may be performed in the order of 2d, 3d, 4d, 5d, 6 d; for another example, it may be performed in the order of 3d, 2d, 4d, 5d, 6 d; for example, the processing may be performed in the order of 3d, 4d, 2d, 5d, and 6d, without limitation.

As shown in fig. 13, event E may include: 1e, the MB-UPF does not detect the data of the multicast service for a long time, and the MB-UPF sends a message of not detecting the data of the multicast service to the MB-SMF, wherein the message contains the identification information of the multicast service of which the data is not detected.

Alternatively, step 1e may also be that the AS/CP sends a notification (e.g., MBs session deactivation) to the MB-SMF to deactivate the multicast/broadcast session, where the notification to deactivate the multicast/broadcast session may include identification information (e.g., one or more of MBs session ID, TMGI, IP multicast address, etc.) of the multicast service. It should be noted that the message sent by the MB-UPF to the MB-SMF that does not detect the data of the multicast service may be a PFCP session message (PFCP session message) or an N4 session message (N4 session message).

2e, the MB-SMF receives a message that the data of the multicast service is not detected or receives a notification of deactivating the multicast/broadcast session, the MB-SMF sends a response message to the MB-UPF to notify the MB-UPF to deactivate the multicast session and cache the data of the multicast service when the subsequent multicast service arrives again, or sends a notification to the MB-SMF when the data of the multicast service arrives at the MB-UPF, and the like.

Further, the MB-SMF may determine whether to release the multicast session tunnel, and if it is determined to release the multicast session tunnel, may also notify the MB-UPF to release the multicast session tunnel. For example, the MB-SMF may send a release notification carrying identification information for the downlink tunnel to the MB-UPF. The identification information of the downlink tunnel may include tunnel information connected to the MB-UPF, such as AN access network tunnel identification (AN tunnel info).

The response message sent by the MB-SMF to the MB-UPF may be a PFCP session message (PFCP session message) or an N4 session message (N4 session message)).

And 3e, after receiving the message that the data of the multicast service is not detected or receiving the Notification of deactivating the multicast/broadcast Session sent by the AS/CP, the MB-SMF sends first information to the second AMF, wherein the first information can be multicast/broadcast Session Deactivation Notification (MBS Session Deactivation Notification) or MBS Session Deactivation, and carries the identification information of the multicast service.

Optionally, if the MB-SMF determines to release the multicast session tunnel (i.e. N3 tunnel or N3MB tunnel between the access network device and the MB-UPF), the first information is further used to indicate that the multicast session tunnel is released.

Optionally, if the MB-SMF determines not to release the multicast session tunnel (i.e. N3 tunnel or N3MB tunnel between the access network device and the MB-UPF), the first information is further used to indicate not to release the tunnel of the multicast session/not to release the multicast session tunnel.

It should be noted that the second AMF may be an AMF serving NAS signaling of the UE, or the second AMF may also be an AMF not serving NAS signaling, for example, the second AMF may be an AMF dedicated to multicast/broadcast service; the second AMF may be an AMF selected from a plurality of AMFs when establishing a multicast session tunnel, and the AMF may transmit signaling to an MB-SMF managing the multicast/broadcast service; or the second AMF may be another AMF, which is not limited herein.

4e, the second AMF receives the first information and sends the first information to the RAN, for example, the first information may be an N2 message. After receiving the first information, the RAN releases air interface resources corresponding to the multicast session, for example, releases a radio bearer used for transmitting data of the multicast/broadcast service, removes/deletes a context (for example, a multicast/broadcast service session context MBS session context) corresponding to the multicast/broadcast service, and so on.

Alternatively, if the RAN receives a notification that the multicast session tunnel is not released/a notification that the multicast session tunnel is not released, the RAN retains a multicast broadcast session service session context (MBS session context) corresponding to the multicast service of the RAN, and the like.

And 5e, the RAN sends the first information to the first AMF.

And 6e, the first AMF receives the first information and sends the first information to the first SMF, the first SMF receives the first information, and the state of the multicast session is marked as deactivation according to the first information.

The above steps are related processes of multicast session deactivation, and further, when data of a multicast service is transmitted again by a multicast mode, in order to ensure transmission of the multicast service, the multicast session needs to be activated, and the process of activating the multicast session refers to the following steps:

s1302a: and the AS/CP determines to start the multicast session, namely, the data of the multicast service is started to be transmitted, and sends a notification for starting the multicast session to the MB-SMF. Accordingly, the MB-SMF receives a notification to start a multicast session.

S1302b: and the MB-UPF detects that the data of the multicast service arrives at the MB-UPF and sends a notice of the data arrival of the multicast service to the MB-SMF. Accordingly, the MB-SMF receives notification of data arrival of the multicast service.

It should be noted that, S1302a and S1302b may be executed either or both, and are not limited.

S1303: the MB-SMF sends second information to the first SMF, which may include identification information of the multicast group. Accordingly, the first SMF receives the second information.

S1304: and the first SMF determines that a PDU session associated with the multicast session exists according to the identification information of the multicast service carried by the second information, and sends an N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer) to the AMF corresponding to the PDU session, wherein the Namf _ Communication _ N1N2Message Transfer may include identification information of the multicast group. Accordingly, the AMF receives N1N2 messaging.

If the UE is in the CM connected state and the PDU session is in the deactivated state, then perform S1305 and then perform S1309, or perform S1309 and then perform S1305 first, or activate the associated PDU session and join the UE to the multicast group at the same time, which is not limited. For the UE in CM idle state, S1306 to S1308 are first executed to activate the associated PDU session, and then S1309 is executed, or S1306 to S1308 may be first executed to return to the connected state (for example, at this time, the associated PDU session is not activated), and then S1309 is executed, or both may be executed, which is not limited.

S1305: if the UE is in the CM-CONNECTED state, the first SMF continues to execute the service request process to activate the associated PDU session.

S1306: the first AMF receives the N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer), and triggers the first AMF to send a paging Message to the RAN in the registration area of the UE. Accordingly, the RAN receives the paging message.

Specifically, step S1306 can be described with reference to step S911, which is not described in detail.

S1307: and the RAN sends a paging message to the UE according to the identification information of the UE or the identification information of the multicast group. Accordingly, the UE receives the paging message sent by the RAN.

S1308: and the UE enters a CM-CONNECTED state, executes a service request flow and activates the PDU session related to the multicast session.

Specifically, step S1308 may be described with reference to step S913, and is not described in detail.

S1309: the first SMF joins the UE to the multicast group.

Specifically, step S1309 may be described with reference to the embodiment corresponding to fig. 5, and is not described in detail.

Based on the method shown in fig. 13, the first SMF receives a message (or first information (e.g., multicast session stop)) that the MB-SMF deactivated the multicast session, marking the multicast session state as deactivated. After receiving a message of starting/starting a multicast session of an MB-SMF or activating a multicast session, for a UE in a CM-CONNECTED state in a multicast group, if an associated PDU session is in a deactivated state, the first SMF activates the associated PDU session, it should be noted that, after the PDU session associated with the multicast session is activated, the first SMF may join the UE in the multicast group by interacting with the RAN and other core network elements, or the first SMF may join the UE in the multicast group by interacting with the RAN and other core network elements to join the UE in the multicast group first and then activate the associated PDU session, or the first SMF may join the UE in the multicast group and activate the associated PDU session at the same time by interacting with the RAN and other core network elements, which is not limited. For the UE in the CM-IDLE state, the network side device may first go through group paging or paging towards a single UE. And after receiving the paging message, the UE initiates a service request flow to activate the PDU session associated with the multicast session. It should be noted that, after the PDU session associated with the multicast session is activated, the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, or the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, and then activate the associated PDU session, or the first SMF may join the UE to the multicast group and activate the associated PDU session at the same time by interacting with the RAN and with other core network elements, which is not limited.

In the following, referring to the 5G system shown in fig. 3a, taking the first terminal as UE, the access network device as RAN, the first session management function network element as first SMF, the second session management function network element as MB-SMF, the first user plane function network element as UPF, the second user plane function network element as MB-UPF, and the access and mobility management function network element as AMF, the method shown in fig. 8 will be described in detail in which the first session management function network element receives the first information from the second session management function network element, marks the state of the multicast session as a deactivated state according to the first information, maps the data of the multicast service to the PDU session, transmits the data of the multicast service in a unicast manner through the PDU session, and subsequently activates/restarts the multicast session after receiving the second information.

The second information may be multicast/broadcast service session start (MBS session start), multicast/broadcast service session activation (MBS session activation), or multicast session activation (multicast session activation).

Fig. 14a is a flowchart of a communication method according to an embodiment of the present application, and as shown in fig. 14a, the communication method may include:

s1401: and establishing a multicast session corresponding to the multicast service, and adding the UE into a multicast group corresponding to the multicast service.

S1401 may refer to S901, and is not described in detail.

Next, in a possible implementation manner, 1D and 3D to 6D in event D are executed, the first SMF receives the first information from the MB-SMF through the first AMF and RAN, determines to deactivate the multicast session according to the first information, and marks the multicast session as a deactivated state, meanwhile, after 6D, the first SMF maps data of the multicast service onto a PDU session, and transmits the data of the multicast service through the PDU session, where the PDU session may be a PDU session associated with the multicast session, or may not be a PDU session associated with the multicast session, and is not limited.

In another possible implementation manner, as shown in fig. 14a, 1E, 3E to 6E in the event E are executed, the first SMF receives the first information from the MB-SMF through the AMF and the RAN, determines to deactivate the multicast session according to the first information, and marks the multicast session as a deactivated state, meanwhile, after 6E, the first SMF maps data of the multicast service onto a PDU session, and transmits the data of the multicast service through the PDU session, where the PDU session may be a PDU session associated with the multicast session or may not be a PDU session associated with the multicast session, which is not limited.

Further, the first SMF may further send third information to the UPF, where the third information is used to indicate to monitor data of the multicast service from the MB-SMF, and send fourth information to the first SMF when the data of the multicast service from the MB-SMF reaches the UPF, so that the first session management function network element activates the multicast session according to the fourth information.

The third information may be sent to the UPF when the first SMF performs N4 session update with the UPF, or may be sent to the UPF before or after the first SMF performs N4 session update with the UPF, which is not limited.

s1402: and the AS/CP determines to start the multicast session, namely, the data of the multicast service is to be transmitted, and sends a notice for starting the multicast session to the MB-SMF. Accordingly, the MB-SMF receives the notification to start the multicast session.

S1403: the MB-SMF sends second information to the first SMF, which may include identification information of the multicast group. Accordingly, the first SMF receives the second information.

S1404: and the UPF detects that the data of the multicast service reaches the UPF, and sends a notification of the data arrival of the multicast service or fourth information of the detected data of the multicast service to the first SMF. Accordingly, the first SMF receives the fourth information from the UPF.

S1405: and the first SMF determines that a PDU session associated with the multicast session exists according to the identification information of the multicast service carried by the second information or the fourth information, and sends an N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer) to the AMF corresponding to the PDU session, where the N1N2Message Transfer may include identification information of the multicast group. Accordingly, the AMF receives N1N2 messaging.

If the UE is in the CM connected state and the PDU session is deactivated, then S1406 is performed, and then S1410 is performed, or first 1410 is performed and then 1405 is performed, or simultaneously (i.e. activating the associated PDU session and adding the UE to the multicast group are performed simultaneously) is not limited. For the UE in CM idle state, the activation of the associated PDU session from 1407 to 1409 is performed first, and then 1410 is performed, or the activation of the associated PDU session and the joining of the UE to the multicast group are performed simultaneously (for example, the associated PDU session is not activated at this time) and then S1410 is performed, without limitation.

S1406: if the UE is in the CM-CONNECTED state, the first SMF continues to execute the service request process to activate the associated PDU session.

S1407: the first AMF receives the N1N2Message Transfer (Namf _ Communication _ N1N2Message Transfer), and triggers the first AMF to send a paging Message to the RAN in the registration area of the UE. Accordingly, the RAN receives the paging message.

Specifically, step S1406 may be described with reference to step S911, which is not described in detail.

S1408: and the RAN sends a paging message to the UE according to the identification information of the UE or the identification information of the multicast group. Accordingly, the UE receives the paging message sent by the RAN.

S1409: and the UE enters a CM-CONNECTED state, executes a service request flow and activates the PDU session related to the multicast session.

Specifically, step S1409 may be as described with reference to step S913, and is not repeated herein.

S1410: the first SMF joins the UE to the multicast group.

Specifically, step S1410 may be described with reference to the embodiment corresponding to fig. 5, and is not described in detail.

Based on the method shown in fig. 14a, the first SMF receives a message (or first information (e.g., multicast session stop)) that the MB-SMF deactivated the multicast session, marking the multicast session state as deactivated. After receiving a message of starting/starting a multicast session of an MB-SMF or activating a multicast session, for a UE in a CM-CONNECTED state in a multicast group, if an associated PDU session is in a deactivated state, the first SMF activates the associated PDU session, it should be noted that after the PDU session associated with the multicast session is activated, the first SMF may add the UE to the multicast group by interacting with the RAN and other core network elements, or the first SMF may add the UE to the multicast group by interacting with the RAN and other core network elements, first add the UE to the multicast group, and then activate the associated PDU session, or the first SMF may add the UE to the multicast group and activate the associated PDU session at the same time by interacting with the RAN and other core network elements, without limitation. For the UE in the CM-IDLE state, the network side device may first go through group paging or paging towards a single UE. And after receiving the paging message, the UE initiates a service request flow to activate the PDU session associated with the multicast session. It should be noted that, after the PDU session associated with the multicast session is activated, the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, or the first SMF may join the UE to the multicast group by interacting with the RAN and with other core network elements, and then activate the associated PDU session, or the first SMF may join the UE to the multicast group and activate the associated PDU session at the same time by interacting with the RAN and with other core network elements, which is not limited.

Different from the multicast session stop (or deactivation flow) shown in step 1b to step 5b of fig. 11, the following steps are performed:

the multicast session release releases/deletes the multicast session when a service provider (content provider) starts/initiates/starts (inter) the multicast session release/delete (MBS session delete or MBS session release or session delete), the information related to the multicast session is released/deleted at the terminal and the access network side during the execution process of releasing/deleting the multicast session or after the execution of the multicast session is completed, and the information related to the multicast session is released/deleted at the first session management function network element and the second session management function network element.

Specifically, the release/deletion of the multicast session may refer to: information related to the multicast service (e.g., qoS information related to the multicast service, etc.) is released/deleted in the terminal; the method comprises the steps of releasing/deleting information related to the multicast service at an access network device (for example, releasing/deleting the context related to the multicast service (for example, the context related to the multicast/broadcast or the context of the multicast/broadcast session or the context of the multicast/broadcast group or the context of the multicast/broadcast service), releasing/deleting tunnel information related to the multicast session, releasing/deleting air interface resources related to the multicast session, releasing/deleting information related to the multicast service in the context of a terminal stored by the access network device, releasing/deleting the tunnel related to the multicast session, releasing/deleting the information related to the multicast service at a first session management function network element and/or a second session management function network element, and the like.

The above method embodiments describe the process of activating/deactivating a multicast session, and activating/deactivating a PDU session associated with the multicast session. Optionally, a scheme of paging a terminal is further provided in this embodiment of the present application, where the scheme of paging a terminal provided in this embodiment of the present application may include that the access network device determines, through data transmitted on a user plane, to page a terminal in a radio resource control inactive (RRC _ inactive) state, or that the core network device triggers the access network device to page the terminal, that is, triggers the access network device to page the terminal through a control plane signaling. Specifically, the method may refer to fig. 14b or fig. 14c described below.

Fig. 14b is a flowchart of a communication method for providing a multicast service according to the present application, and as shown in fig. 14b, the method may include:

s1401b: the access network equipment receives the data of the multicast service.

Wherein the access network device may be the access network device in fig. 2.

Illustratively, the access network device may receive data for a multicast service from the MB-UPF.

S1402b: and the access network equipment determines to activate the multicast service according to the data.

The description of the multicast service may refer to the above description, and is not repeated.

It should be noted that, activating the multicast service may also be described as activating a multicast session corresponding to the multicast service, or activating a terminal in a multicast group corresponding to the multicast service, so that the terminal in the multicast group is in an RRC connected state, and the like.

The step of determining, by the access network device, to activate the multicast service according to the data includes: the access network equipment determines that the received data corresponds to the multicast service, determines that the multicast service is in a deactivated state, and determines to activate the multicast service. The multicast service being in the deactivated state may include that a terminal in an RRC _ inactive state exists in a multicast group corresponding to the multicast service, and the like.

For example, the determining, by the access network device, that the received data corresponds to the multicast service may include: the access network equipment determines whether the tunnel for transmitting the data corresponds to the multicast service according to the corresponding relation between the information of the tunnel for transmitting the data and/or the information of the tunnel and the identification information of the multicast service, determines that the received data corresponds to the data of the multicast service if the tunnel for transmitting the data corresponds to the multicast service, and otherwise determines that the received data does not correspond to the multicast service.

The identification information of the multicast service is used to identify the multicast service, and the description of the identification information of the multicast service may refer to the above description, which is not repeated. In the embodiment of the present application, in a case where data corresponds to a multicast service, the data may be referred to as data of the multicast service.

Wherein the information of the tunnel can be used to identify a tunnel. In this embodiment of the present application, the tunnel used for transmitting data of a multicast service between an access network device and an MB-UPF may be a tunnel established by a unicast transmission manner (or referred to as a unicast tunnel), or may be a tunnel established by a multicast transmission manner (or referred to as a multicast tunnel). The unicast transmission mode may refer to: the downstream node (such as access network equipment) allocates the information of the tunnel for the multicast service to the upstream node (such as MB-UPF), so that the upstream node can know to which downstream node the data of the multicast service is sent, and unicast transmission can also be referred to as point-to-point transmission. Multicast transmission may refer to: the upstream node (such as MB-UPF) allocates a common tunnel information (or information called multicast tunnel) to one or more downstream nodes (such as access network devices) for the data of the multicast service, so that the upstream node can send the data of the multicast service to one or more downstream nodes according to the common tunnel information, the downstream nodes can receive the data of the multicast service, and the multicast transmission can also be called a point-to-multipoint transmission mode.

In the embodiment of the application, the information of the tunnel is different under different establishment modes. After a tunnel for transmitting the multicast service data is established between the access network device and the MB-UPF, the correspondence between the information of the tunnel for transmitting the multicast service data and the identification information of the multicast service may be stored in the access network device. The following describes a process of determining that data transmitted on a tunnel corresponds to a multicast service in terms of different establishment manners:

in case one, a tunnel for transmitting data of a multicast service is established in a unicast transmission manner.

Specifically, the establishing a tunnel for transmitting data of the multicast service between the MB-UPF and the access network device in a unicast transport (unicast transport) manner, that is, the establishing a tunnel between the MB-UPF and the access network device in a point-to-point tunnel (point-to-point tunnel) manner may include:

the access network device sends the information of the tunnel to the MB-UPF through the core network device (such as SMF, MB-SMF), for example, the information is carried in the configuration information corresponding to the multicast session and sent to the MB-UPF, the MB-UPF receives the information of the tunnel, and correspondingly stores the corresponding relationship between the information of the tunnel and the identification information of the multicast service, so that the MB-UPF sends the received data of the multicast service to the access network device according to the corresponding relationship, correspondingly, the access network device can also store the corresponding relationship between the identification information of the multicast service and the information of the tunnel, so that the access network device knows that the data received from the tunnel corresponding to the information of the tunnel is the data of the multicast service according to the corresponding relationship, and the tunnel establishment from the MB-UPF to the data for transmitting the multicast service is completed.

The tunnel may be referred to as a General Packet Radio Service (GPRS) tunneling protocol-user plane (GTP-U) tunnel (or a downlink tunnel). The information of the Tunnel may include access network Tunnel information (AN Tunnel Info) of the access network device or a Tunnel End Identifier (TEID) of the access network device, and the information of the Tunnel may be used to establish a Tunnel (such as a GTP-U Tunnel) between the access network device and the MB-UPF for transmitting data of the multicast service.

In a first case, when a multicast session corresponding to a multicast service is activated, after the MB-UPF receives data of the multicast service from the application server, the MB-UPF may obtain information of a tunnel corresponding to the tunnel for transmitting the data of the multicast service according to a correspondence between identification information of the multicast service and information of the tunnel, and send the data of the multicast service to the access network device through the tunnel according to the obtained information of the tunnel. Correspondingly, the access network device receives the data from the tunnel, and then learns that the data transmitted on the tunnel is the data of the multicast service according to the information of the tunnel corresponding to the tunnel and/or the corresponding relation between the identification information of the multicast service and the information of the tunnel, and determines that the data corresponds to the multicast service.

For example, three tunnels are established between the base station and the MB-UPF: if the default/pre-configuration is that only the tunnel 1 transmits the data of the multicast service, the base station may directly determine that the data received from the tunnel 1 is the data of the multicast service after receiving the data from the tunnel 1. Or, the base station stores the following corresponding relations { tunnel 1, multicast service 1}, { tunnel 2, multicast service 2} and { tunnel 3, multicast service 3}, in advance, after receiving data from tunnel 1, the base station searches for the corresponding relation { tunnel 1, multicast service 1} by using the information of the tunnel of tunnel 1 as an index, and determines that the received data of the multicast service is the data of multicast service 1 according to the corresponding relation.

And in case two, a tunnel for transmitting the data of the multicast service is established in a multicast transmission mode.

The tunnel established by the multicast transmission method for transmitting the data of the multicast service may be a multicast tree, and the multicast tree may correspond to/identify one or more multicast services. The information of the tunnel may be a multicast IP address, which may include a Common TEID (C-TEID) or an IP address of MB-UPF, etc.

Specifically, taking the information of the tunnel as a multicast IP address as an example, establishing the tunnel between the MB-UPF and the access network device according to a multicast transport mode (multicast transport) may include: the MB-UPF and the corresponding one or more access network devices may form a multicast tree, the multicast tree may be used to transmit data of a multicast service, the MB-UPF is a multicast source, and the one or more access network devices corresponding to the MB-UPF may serve as a receiving end of the multicast tree, and the one or more access network devices include the access network device in S1 b. The MB-SMF or MB-UPF may allocate a multicast IP address to the multicast tree and send the multicast IP address to one or more access network devices, and the one or more access network devices may receive the multicast IP address and correspondingly store a corresponding relationship between the multicast IP address and identification information of a multicast service, so that the one or more access network devices join the multicast tree corresponding to the multicast IP address.

In case two, when the multicast session corresponding to the multicast service is activated, after the MB-UPF receives the data of the multicast service from the application server, the MB-UPF may encapsulate the multicast IP address and the data of the multicast service in a data packet, and send the data to one or more access network devices through a multicast tree, after receiving the data packet, the access network device may obtain the multicast IP address from the data packet, and further determine that the received data corresponds to the multicast service according to the correspondence between the multicast IP address and the identification information of the multicast service, and is the data of the multicast service.

S1403b: and the access network equipment sends a paging message to the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service.

For example, the sending, by the access network device, the paging message to the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service may include: and the access network equipment determines the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service and sends a paging message to the terminal in the RRC _ inactive state.

The number of terminals in the RRC _ inactive state may be one or more. The determining, by the access network device, a terminal in an RRC _ inactive state in a multicast group corresponding to a multicast service may include: the access network device may use the identification information of the multicast service as an index to find the context of the terminal stored in the access network device, and find the context of the terminal storing the identification information of the multicast service. If the found context of the terminal contains an inactive radio network temporary identifier (I-RNTI), determining that the terminal is in an RRC-inactive state, and further determining a paging area of the terminal in the RRC-inactive state.

In the embodiment of the application, the paging message can be used for paging the terminal in the RRC-inactive state.

In a possible design, the paging message may be a paging message for one terminal, that is, a paging message with per UE granularity, where one paging message pages only one terminal, and at this time, the paging message may carry identification information of the terminal. For example, assuming that the ue is in the RRC _ inactive state and includes a first terminal and a second terminal, the access network device may send a first paging message in a Notification Area (RNA) of a radio access network of the first terminal, where the first paging message includes identification information of the first terminal, and after the first terminal monitors a paging channel for a paging message carrying the identification information of the first terminal, the first terminal may transition from the RRC _ inactive state to the RRC connected state. Similarly, the access network device may send a second paging message in the RNA of the second terminal, where the second paging message includes the identification information of the second terminal, and after the second terminal monitors the paging message carrying the identification information of the second terminal on the paging channel, the second terminal may transition from the RRC _ inactive state to the (switch to) RRC connected state.

In this embodiment, the RNA of each terminal may be configured by the access network device and pre-allocated to the terminal. The RNA for each terminal may comprise one or more cells and the RNA for the terminal may comprise the signal coverage area of one or more access network devices. For example, the RNA for UE1 may contain the signal coverage areas for base stations No. 1, no. 2, and No. 3.

In yet another possible design, the paging message may also be a group paging message for multiple terminals, that is, a paging message with multiple UEs as granularity, where the paging message may be referred to as a group paging message, so as to reduce the number of times of sending the paging message and save signaling overhead. The group paging message may carry identification information of the multicast service. If the terminal monitors the identification information of the multicast service on the paging channel, the terminal may transition from an RRC _ inactive state to an RRC connected state. For example, assuming that the RRC _ inactive state includes a first terminal and a second terminal, the access network device may send a paging message within the RNA of the first terminal and the RNA of the second terminal, where the paging message includes identification information of the multicast service.

Optionally, in order to save signaling overhead, the sending, by the access network device, the paging message in the RNA of the first terminal and the RNA of the second terminal includes: in a paging cycle, the access network equipment sends a paging message once in an overlapping area of the RNA of the first terminal and the RNA of the second terminal, that is, if the RNAs of different terminals overlap, only a group paging message is sent once in the overlapping area, so that the signaling overhead of paging can be reduced.

The paging cycle may refer to a time interval for transmitting the paging message. The paging cycle can be set according to the needs, and is not limited.

For example, UE1 and UE2 in RRC-inactive state are pre-assigned with an RNA, for example, the RNA of UE1 includes signal coverage areas of base stations No. 1, no. 2, and No. 3, and the RNA of UE2 includes signal coverage areas of base stations No. 2, no. 3, and No. 4. Assuming that per UE is used as granularity to send paging messages, base stations No. 1, no. 2, and No. 3 respectively send paging messages carrying identification information of UE1 in RNA of UE1, and send 3 paging messages altogether, and base stations No. 2, no. 3, and No. 4 send 3 paging messages carrying identification information of UE2 in RNA of UE 2. If group paging is performed by using multiple UEs as granularity, and a paging message is sent once in an overlapping area, because the signal coverage areas of base stations No. 2 and No. 3 in the RNA of UE1 and the signal coverage areas of base stations No. 2 and No. 3 in the RNA of UE2 are overlapped, while the signal coverage area of base station No. 1 in the RNA of UE1 and the RNA of UE2 do not have an overlapping area, and the signal coverage area of base station No. 4 in the RNA of UE2 and the RNA of UE1 do not have an overlapping area, in one paging cycle, paging messages carrying identification information (e.g., MBS session ID) of multicast service can be sent to the signal coverage area of base station No. 1, the signal coverage areas of base stations No. 2 and No. 3, and the signal coverage area of base station No. 4, i.e., 4 paging messages are sent, which saves 2 paging messages compared with paging using UEs as granularity, and reduces paging signaling overhead.

Based on the method shown in fig. 14b, when the access network device determines that the data received from the user plane is data of the multicast service, the access network device is triggered to page the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service, so as to ensure that the terminal in the multicast group normally receives the data of the multicast service.

Fig. 14c is a communication method for providing a multicast service according to the present application, and as shown in fig. 14c, the method may include:

s1401c: and the session management function network element determines the multicast session corresponding to the activated multicast service and sends information for indicating the multicast session corresponding to the activated multicast service to the access and mobility management function network element. Accordingly, the access and mobility management function network element receives the information.

The session management network element may be the MB-SMF described above, and the information for indicating activation of the multicast session may be the second information described above, where the information may carry identification information of the multicast service. Specifically, the relevant description of the information may refer to the relevant description of the second information in S801 above, the session management function network element may determine to activate the multicast session by referring to the method described in the embodiment corresponding to fig. 8, and the identifier information of the multicast service may refer to the above, which is not described again.

It should be noted that the access and mobility management function network element in S1401c may be the second access and mobility management network element, or may be an AMF capable of providing NAS signaling service for any terminal in a multicast group corresponding to the multicast service, which is not limited in this application. Taking the session management network element as MB-SMF as an example, the access and mobility management network element may be selected by NRF and indicated to MB-SMF, that is, the access and mobility management network element may be AMF selected by MB-SMF from NRF, for example, MB-SMF may send an inquiry request carrying identification information of multicast service to NRF, the inquiry request requests to inquire AMF capable of providing NAS signaling service for terminals in the multicast group, after the NRF receives the inquiry request, the access and mobility management network element is selected from a plurality of AMFs according to the identification information of multicast service, and the access and mobility management network element is indicated to MB-SMF.

S1402c: and the access and mobility management function network element sends information for indicating the activation of the multicast session corresponding to the multicast service to the access network equipment. Accordingly, the access network device receives the information.

The access and mobility management functional network element may carry the information in an N2 message and send the information to the access network device. S1403c: and the access network equipment sends a paging message to the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service according to the information for indicating the activation of the multicast session.

For example, the sending, by the access network device, the paging message to the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service according to the information indicating that the multicast session corresponding to the multicast service is activated may include: the access network equipment determines to activate the multicast session/activate the multicast service according to the information for indicating the multicast session corresponding to the activated multicast service, determines the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service, and sends a paging message to the terminal in the RRC _ inactive state.

The process of the access network device determining the terminal in the RRC _ inactive state in the multicast group corresponding to the multicast service and sending the paging message to the terminal in the RRC _ inactive state may refer to the process in S1403b, which is not described in detail.

Based on the method shown in fig. 14c, the access network device may acquire, from the core network, a multicast session corresponding to the activated multicast service, and then trigger the access network device to page a terminal in an RRC _ inactive state in a multicast group corresponding to the multicast service, so as to ensure that the terminal in the multicast group normally receives data of the multicast service.

The above-mentioned scheme provided by the embodiments of the present application is mainly introduced from the perspective of interaction between the nodes. It is to be understood that each node, such as the first session management function network element, the access network device, the first terminal, etc., contains corresponding hardware structures and/or software modules for performing each function in order to implement the above functions. Those of skill in the art will readily appreciate that the present application is capable of hardware or a combination of hardware and computer software implementing the various illustrative algorithm steps described in connection with the embodiments disclosed herein. Whether a function is performed in hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the embodiment of the present application, according to the above method example, functional modules of the first session management functional network element, the access network device, the first terminal, and the like may be divided, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated in one processing module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. It should be noted that, in the embodiment of the present application, the division of the module is schematic, and is only one logic function division, and there may be another division manner in actual implementation.

Fig. 15 is a schematic composition diagram of a communication device 150 according to an embodiment of the present application, where the communication device 150 may be a first session management function network element or a chip or a system on chip in the first session management function network element, or the communication device may be an access network device on an access network device or a chip or a system on chip in the access network device. In one possible design, as shown in fig. 15, the communication device 150 may include: a processing unit 1501;

a processing unit 1501, configured to determine whether a PDU session to be deactivated is associated with a multicast session corresponding to a multicast service, determine whether the multicast session is in an active state, if the PDU session is associated with the multicast session and the multicast session is in the active state, keep the PDU session in the active state, and if the PDU session is associated with the multicast session and the multicast session is in the inactive state, deactivate the PDU session. For example, the processing unit 1501 may support the communication apparatus 150 to perform S501 to S504.

Specifically, in this possible design, all relevant contents related to the first session management function network element or each step in the method embodiment shown in fig. 5 to fig. 7 may be referred to the functional description of the corresponding functional module, which is not described herein again. The communication apparatus 150 in this possible design is used to perform the first session management function element or function in the communication method shown in fig. 5 to 7, so that the same effect as the above-mentioned communication method can be achieved.

As still another implementation, the communication device 150 shown in fig. 15 may include: a processing module and a communication module. The processing module may integrate the functions of the processing unit 1501. The processing module is used to control and manage the actions of the communication device 150, e.g., the processing module is used to support the communication device 150 to perform S501-S504 and other processes of the techniques described herein. The communication module is used to support the communication device 150 to perform steps 501, 504, 607, etc. and communicate with other network entities. Further, the communication device 150 shown in fig. 15 may further include a storage module for storing program codes and data of the communication device 150.

The processing module may be a processor or a controller. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. A processor may also be a combination of computing functions, e.g., comprising one or more microprocessors, a DSP and a microprocessor, or the like. The communication module may be a transceiver circuit or a communication interface, etc. The storage module may be a memory. When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the communication device 150 shown in fig. 15 may be the communication device 400 shown in fig. 4.

Fig. 16 is a schematic composition diagram of a communication device 160 according to an embodiment of the present application, where the communication device 160 may be a first session management function network element or a chip or a system on a chip in the first session management function network element. As shown in fig. 16, the communication device 160 may include: a receiving unit 1601, a processing unit 1602;

a receiving unit 1601 is configured to receive second information, which is used to indicate that a multicast session is activated, from a second session management function network element. For example, the receiving unit 1601 may support the communication device 160 to perform S802.

A processing unit 1602, configured to notify the access network device to add the first terminal to a multicast group corresponding to a multicast session, where the first session management functional network element corresponds to the first terminal, and the second session management functional network element corresponds to the multicast group. For example, processing unit 1602 may support communication device 160 in performing S802.

Specifically, in this possible design, all relevant contents of each step related to the first session management function network element in the method embodiment shown in fig. 8 to 14a may be referred to the functional description of the corresponding functional module, which is not described herein again. The communication device 160 in this possible design is used to perform the function of the first session management function network element in the communication method shown in fig. 8 to 14a, so that the same effect as the above-mentioned communication method can be achieved.

As still another implementation, the communication device 160 shown in fig. 16 may include: a processing module and a communication module. The communication module may integrate the functions of the receiving unit 1601. The processing module can integrate the functions of the processing unit 1602. The processing module is used to control and manage the actions of the communication device 160, e.g., the processing module is used to support the communication device 160 to perform S802 and other processes of the techniques described herein. The communication module is used to support communication of the communication device 160 with other network entities. Further, the communication device 160 shown in fig. 16 may also include a storage module for storing program codes and data of the communication device 160. When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the communication device 160 shown in fig. 16 may be the communication device 400 shown in fig. 4.

Fig. 17 is a schematic composition diagram of a communication apparatus 170 according to an embodiment of the present disclosure, where the communication apparatus 170 may be an access network device or a chip or a system on chip in the access network device. As shown in fig. 17, the communication device 170 may include: processing section 1701, transmitting section 1702;

the processing unit 1701 is configured to determine to deactivate a multicast session corresponding to the multicast service. For example, the processing unit 1701 may support the communication device 170 to perform S902b, S1102b.

A sending unit 1702, configured to send eighth information used for indicating to deactivate the multicast session to the first access and mobility management function network element or the second access and mobility management function network element, where the first access and mobility management function network element corresponds to a terminal in the multicast group corresponding to the multicast service, and the second access and mobility management function network element corresponds to the multicast group corresponding to the multicast service. For example, the transmitting unit 1702 may support the communication device 170 to perform S902b, S902c, S1102b, S1102c, and the like.

Specifically, in this possible design, all relevant contents related to each step in the method embodiments shown in fig. 9 and fig. 11 may be referred to the functional description of the corresponding functional module, and are not described herein again. The communication apparatus 170 in this possible design is used to perform the functions in the communication methods shown in fig. 9 and 11, and therefore the same effects as those in the above-described communication methods can be achieved.

As another implementation, the communication device 170 shown in fig. 17 may include: a processing module and a communication module. The communication module may integrate the functionality of the sending unit 1702. The processing modules may integrate the functions of the processing unit 1701. The processing module is configured to control and manage actions of the communication device 170, for example, the processing module is configured to support the communication device 170 to perform S902b, S1102b, and other processes of the techniques described herein. The communication module is used to support the communication device 170 to perform S902b, S902c, S1102b, S1102c and communication with other network entities. Further, the communication device 170 shown in fig. 17 may further include a storage module for storing program codes and data of the communication device 170. When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the communication device 170 shown in fig. 17 can be the communication device 400 shown in fig. 4.

Fig. 18 is a schematic composition diagram of a communication device 180 according to an embodiment of the present application, where the communication device 180 may be a first terminal or a chip or a system on a chip in the first terminal. As shown in fig. 18, the communication device 180 may include: receiving section 1801, processing section 1802, and transmitting section 1803;

a receiving unit 1801, configured to receive a paging message.

A processing unit 1802 is configured to determine that a PDU session associated with a multicast session is in a deactivated state.

A sending unit 1803, configured to send a first message (e.g., a service request) to the access network device, where the first message is used to activate a PDU session associated with the multicast session.

Specifically, in this possible design, all relevant contents of each step related to the first terminal in the method embodiment shown in fig. 5 to 14a may be referred to the functional description of the corresponding functional module, and are not described herein again. The communication apparatus 180 described in this possible design is used to perform the function of the first terminal in the communication method shown in fig. 5 to 14a, and therefore the same effect as the above-described communication method can be achieved.

As still another implementation, the communication device 180 shown in fig. 18 may include: a processing module and a communication module. The processing module may integrate the functionality of the processing unit 1802 and the communication module may integrate the functionality of the receiving unit 1801 and the transmitting unit 1803. The processing module is used for supporting the communication device 180 to control and manage the action of the communication device 180, and the communication module is used for supporting the communication between the communication device 180 and other network entities. Further, the communication device 180 shown in fig. 18 may further include a storage module for storing program codes and data of the communication device 180. When the processing module is a processor, the communication module is a communication interface, and the storage module is a memory, the communication device 180 shown in fig. 18 is the communication device 400 shown in fig. 4.

Fig. 19 is a schematic diagram illustrating a communication system according to an embodiment of the present disclosure, and as shown in fig. 19, the communication system may include a terminal 190, an SMF191, and a RAN192. A first AMF, a second AMF, MB-SMF may also be included, where SMF191 corresponds to terminal 190 and MB-SMF corresponds to a multicast group.

Here, the terminal 190 has the same function as the communication device 180, and the SMF191 has the same function as the communication device 150 or the communication device 160. RAN192 is functionally identical to communication device 150 or communication device 170.

For example, in an example, the SMF191 or the RAN192 is configured to determine whether a PDU session to be deactivated is associated with a multicast session corresponding to a multicast service, determine whether the multicast session is in an active state, keep the PDU session in the active state if the PDU session is associated with the multicast session and the multicast session is in the active state, and deactivate the PDU session if the PDU session is associated with the multicast session and the multicast session is in the deactivated state.

In yet another example, the SMF191 is configured to receive the second information indicating that the multicast session is activated from the MB-SMF, and notify the RAN192 to join the first terminal to the multicast group corresponding to the multicast session.

In another example, the RAN192 is configured to determine to deactivate a multicast session corresponding to a multicast service, and send eighth information indicating that the multicast session is deactivated to a first AMF or a second AMF, where the first AMF corresponds to a terminal in a multicast group corresponding to the multicast service, and the second AMF corresponds to the multicast group corresponding to the multicast service.

Terminal 190 is configured to receive a paging message from RAN192, determine that a PDU session associated with a multicast session is in a deactivated state, and send a first message (e.g., a service request) to RAN192, where the first message is used to activate the PDU session associated with the multicast session.

Specifically, the execution process of each network element in fig. 19 may refer to the execution steps of the corresponding network elements in the methods shown in fig. 5 to fig. 14a, which are not described in detail.

The embodiment of the application also provides a computer readable storage medium. All or part of the processes in the above method embodiments may be performed by a computer program instructing related hardware, where the program may be stored in the above computer-readable storage medium, and when executed, the program may include the processes in the above method embodiments. The computer readable storage medium may be the terminal device of any of the foregoing embodiments, such as: including internal storage units of the data transmitting end and/or the data receiving end, such as a hard disk or a memory of the terminal device. The computer readable storage medium may also be an external storage device of the terminal apparatus, such as a plug-in hard disk, a Smart Memory Card (SMC), a Secure Digital (SD) card, a flash memory card (flash card), and the like, provided on the terminal apparatus. Further, the computer-readable storage medium may include both an internal storage unit and an external storage device of the terminal apparatus. The computer-readable storage medium stores the computer program and other programs and data required by the terminal device. The above-described computer-readable storage medium may also be used to temporarily store data that has been output or is to be output.

The embodiment of the application also provides a computer instruction. All or part of the flow of the above method embodiments may be performed by computer instructions to instruct relevant hardware (such as a computer, a processor, a network device, a terminal, and the like). The program may be stored in the computer-readable storage medium described above.

It should be understood that in the embodiment of the present application, "B corresponding to a" means that B is associated with a. For example, B may be determined from A. It should also be understood that determining B from a does not mean determining B from a alone, but may also be determined from a and/or other information. In addition, the term "connect" in the embodiment of the present application refers to various connection manners, such as direct connection or indirect connection, to implement communication between devices, and this is not limited in this embodiment of the present application.

The "transmission" appearing in the embodiments of the present application refers to a bidirectional transmission, including actions of transmission and/or reception, unless otherwise specified. Specifically, "transmission" in the embodiment of the present application includes transmission of data, reception of data, or both transmission of data and reception of data. Alternatively, the data transmission herein includes uplink and/or downlink data transmission. The data may include channels and/or signals, uplink data transmission, i.e., uplink channel and/or uplink signal transmission, and downlink data transmission, i.e., downlink channel and/or downlink signal transmission. In the embodiments of the present application, "network" and "system" represent the same concept, and a communication system is a communication network.

In the description of the present application, a "/" indicates a relationship in which the objects associated before and after are an "or", for example, a/B may indicate a or B; in the present application, "and/or" is only an association relationship describing an associated object, and means that there may be three relationships, for example, a and/or B, and may mean: a exists singly, A and B exist simultaneously, and B exists singly, wherein A and B can be singular or plural. Also, in the description of the present application, "a plurality" means two or more than two unless otherwise specified. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple. In addition, in order to facilitate clear description of technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "exemplary" or "for example" are used to mean serving as examples, illustrations or explanations. Any embodiment or design described herein as "exemplary" or "such as" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present relevant concepts in a concrete fashion for ease of understanding.

Through the above description of the embodiments, it is clear to those skilled in the art that, for convenience and simplicity of description, the foregoing division of the functional modules is merely used as an example, and in practical applications, the above function distribution may be completed by different functional modules according to needs, that is, the internal structure of the device may be divided into different functional modules to complete all or part of the above described functions.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. For example, the above-described device embodiments are merely illustrative, and for example, the division of the modules or units is only one logical functional division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another device, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may be one physical unit or multiple physical units, that is, may be located in one place, or may be distributed in multiple different places. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a readable storage medium. Based on such understanding, the technical solutions of the embodiments of the present application, which are essential or which contribute to the prior art, or all or part of the technical solutions, may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions to enable a device, such as: the method can be a single chip, a chip, or a processor (processor) for executing all or part of the steps of the method described in the embodiments of the present application. And the aforementioned storage medium includes: a U disk, a removable hard disk, a ROM, a RAM, a magnetic disk or an optical disk, and various media capable of storing program codes.

The above description is only an embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions within the technical scope of the present disclosure should be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of communication, the method comprising:

the access network equipment receives information which is from an access and mobility management network element and is used for indicating the multicast session corresponding to the activated multicast service;

and the access network equipment sends a paging message to a terminal in a radio resource control _ non-activated RRC _ inactive state in a multicast session corresponding to the multicast service according to the information.

2. The method of claim 1, wherein the information indicating activation of the multicast session corresponding to the multicast service comprises: the multicast broadcast service session activates the MBS session activation.

3. The method according to claim 1 or 2, wherein the information for indicating activation of the multicast session corresponding to the multicast service carries identification information of the multicast service.

4. The method according to claim 3, wherein the identification information of the multicast service is: the multicast/broadcast service session identifier MBS session ID, the temporary mobile group identifier TMGI of the multicast session, or the IP multicast address.

5. The method according to claim 1 or 2, wherein the sending, by the access network device, the paging message to the terminal in the radio resource control _ inactive RRC _ inactive state in the multicast session corresponding to the multicast service includes:

the access network equipment determines the terminal in the RRC _ inactive state in the terminals of the multicast session;

and the access network equipment sends a paging message to the terminal in the RRC _ inactive state.

6. The method according to claim 1 or 2, wherein the terminals in RRC _ inactive state comprise a first terminal and a second terminal;

the sending, by the access network device, the paging message to the terminal in the RRC _ inactive state in the multicast session corresponding to the multicast service includes: and the access network equipment sends a paging message in a notification area RNA of a radio access network of the first terminal and an RNA of the second terminal, wherein the paging message comprises identification information of the multicast service.

7. The method of claim 5, wherein the identification information of the multicast service is: the multicast/broadcast service session identifier MBS session ID, the temporary mobile group identifier TMGI of the multicast session, or the IP multicast address.

8. The method according to claim 1 or 2, characterized in that the method further comprises:

the access network device receives ninth information from the access and mobility management function network element, where the ninth information is used to indicate/notify that a multicast session corresponding to the multicast service is deactivated;

and the access network equipment deactivates the multicast session according to the ninth information.

9. The method of claim 8, wherein the means for indicating/notifying deactivation of multicast session deactivates MBS session deactivation for multicast broadcast service session.

10. A communication system, the communication system comprising:

a session management function network element, configured to determine a multicast session corresponding to an activated multicast service, and send information indicating activation of the multicast session to an access and mobility management network element;

the access and mobility management network element is used for receiving the information and sending the information to the access network equipment;

and the access network equipment is used for receiving the information and sending a paging message to a terminal in a radio resource control _ inactive RRC _ inactive state in a multicast session corresponding to the multicast service according to the information.

11. The communication system of claim 10, wherein the information indicating activation of the multicast session comprises a multicast broadcast service session activation MBS session activation.

12. The communication system according to claim 10 or 11, wherein the information for indicating activation of the multicast session corresponding to the multicast service carries identification information of the multicast service.

13. The communication system according to claim 12, wherein the identification information of the multicast service is: the multicast/broadcast service session identifier MBS session ID, the temporary mobile group identifier TMGI of the multicast session, or the IP multicast address.

14. The communication system according to claim 10 or 11,

the access and mobility management element is configured to receive ninth information and send the ninth information to the access network device, where the ninth information is used to indicate/notify a multicast session for deactivating a multicast service;

the access network device is configured to deactivate the multicast session according to the ninth information.

15. The communication system according to claim 14, wherein the session management function network element is further configured to send the ninth information to the access and mobility management network element.

16. The communication system of claim 15, wherein the ninth information comprises a multicast broadcast service session deactivation MBS session deactivation.

17. The communication system according to claim 10 or 11,

the session management function network element is further configured to receive a multicast broadcast service session activation notification from an application function AF; alternatively, the first and second electrodes may be,

and the session management function network element is further configured to receive a data arrival notification of the multicast service from a multicast broadcast-user plane function MB-UPF.

18. The communication system according to claim 10 or 11,

the session management function network element is further configured to receive a multicast broadcast service session deactivation message from an application function AF, where the multicast broadcast service session deactivation message carries a multicast broadcast service session identifier MBS session ID corresponding to the multicast session that needs to be deactivated.

19. The communication system of claim 18,

and the session management function network element is further configured to instruct a multicast broadcast-user plane function MB-UPF to report or notify the arrival of next multicast session data.

20. The communication system according to claim 10 or 11, wherein the session management function network element is a multicast broadcast-session management function, MB-SMF.

21. A communications apparatus, comprising:

a memory for storing a computer program;

a processor for calling and running the computer program from the memory to perform the communication method of any one of claims 1-9.

22. A computer-readable storage medium, characterized by comprising a computer program which, when run on a computer, causes the computer to perform the communication method according to any one of claims 1 to 9.