CN113630824A

CN113630824A - Service switching method, device and system

Info

Publication number: CN113630824A
Application number: CN202011523485.4A
Authority: CN
Inventors: 宗在峰; 朱奋勤
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-05-08
Filing date: 2020-12-21
Publication date: 2021-11-09
Also published as: WO2021223620A1

Abstract

The embodiment of the application discloses a service switching method, a device and a system, wherein the method comprises the following steps: the method comprises the steps that a first session management network element receives a first message which is from a first mobility management network element and used for requesting context information of an EPS bearer corresponding to a PDU session of a first terminal, the first mobility management network element is located in a first network, the PDU session is served by the first session management network element, and the PDU session is associated with a multicast service; and the first session management network element sends the context information of the EPS bearer to the first mobility management network element according to the first message, wherein the context information of the EPS bearer comprises the context of the EPS bearer corresponding to the multicast service. The scheme can be used in the fields of communication technology field, artificial intelligence, Internet of vehicles, intelligent home networking and the like.

Description

Service switching method, device and system

The present application claims priority of chinese patent application entitled "service switching method, apparatus and system" filed by the national intellectual property office on 08/05/2020, application number 202010383295.0, 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 service switching method, device and system.

Background

In the third Generation partnership project (3 GPP), with the rapid development of wireless communication technology, a Fifth Generation (5G) mobile communication network (5G network for short) has come up, and the 5G network can coexist with an existing fourth Generation (4G) network to realize interworking between them.

In a 5G network, there is a need for a network side device to simultaneously transmit data of the same service to multiple terminals, that is, a requirement for point-to-multipoint multicast service transmission. In order to meet such a requirement, conventionally, data of the same multicast service transmitted to a plurality of terminals share the same User Plane Function (UPF) through a multicast broadcast/multicast mode, and the data of the multicast service is transmitted to the plurality of terminals through the same UPF.

When a terminal moves from a 5G network to a coverage area of a base station in a 4G network, if the terminal receives data of the multicast service in a multicast broadcast/multicast mode at the 5G network, when the terminal moves to the coverage area of the base station in the 4G network, how the terminal receives the data of the multicast service through the base station in the 4G network and ensuring the continuity of the data of the multicast service sent to the terminal become problems to be solved urgently.

Disclosure of Invention

The embodiment of the application provides a service switching method, a service switching device and a service switching system, so as to switch a multicast service from a first network to a second network, and carry data for transmitting the multicast service through an Evolved Packet System (EPS) in the second network.

In order to achieve the above purpose, the embodiment of the present application adopts the following technical solutions:

in a first aspect, an embodiment of the present application provides a service switching method, where the method may include: the first session management network element receives a first message which is from a first mobility management network element and used for requesting context information of an EPS bearer corresponding to the PDU session, the first session management network element sends the context information of the EPS bearer to the first mobility management network element according to the first message, and the context information of the EPS bearer comprises a context of the EPS bearer corresponding to the multicast service. Wherein the first mobility management network element is in a first network, the PDU session is a PDU session for the first terminal, the PDU session is serviced by the first session management network element, and the PDU session is associated with a multicast service.

Based on the method of the first aspect, the first session management network element determines context information of an EPS bearer corresponding to the multicast service, and sends the context information of the EPS bearer corresponding to the multicast service to the first mobility management network element when the first terminal is switched, so that the first mobility management network element triggers the second mobility management network element to establish a tunnel of the EPS bearer corresponding to the multicast service, so that when the first terminal is switched to the second network, the application server sends data of the multicast service to the first terminal through the EPS bearer, thereby ensuring continuity of multicast service transmission. Meanwhile, when the first terminal moves out of the area corresponding to the EPS bearer to the MBMS area, the data of the multicast service is stopped to be sent through the EPS bearer, and the data of the multicast service is switched to be sent through the MBMS bearer, so that the data transmission performance is improved.

In one possible design, the context of the EPS bearer includes a context of at least one EPS bearer corresponding to the multicast service, and the context of each EPS bearer includes an identifier of the EPS bearer and a QoS parameter of the EPS bearer.

Based on the possible design, the context of one or more EPS bearers can be determined, and the transmission requirement of the multicast service is met by transmitting the data of the multicast service through the one or more EPS bearers corresponding to the multicast service.

In one possible design, the method further includes: and the first session management network element determines the context of the EPS bearer corresponding to the multicast service.

Based on the possible design, the first session management network element determines the context of the EPS bearer corresponding to the multicast service, reduces the signaling overhead of acquiring the context information of the EPS bearer, and acquires the context of the EPS bearer from the acquired context information of the EPS bearer.

In one possible design, the determining, by the first session management network element, the context of the EPS bearer corresponding to the multicast service includes: and the first session management network element determines to allow the multicast service to be switched to the second network, and determines the context of the EPS bearer corresponding to the multicast service.

Based on the possible design, when the multicast service supports switching to the second network, the context of the EPS bearer corresponding to the multicast service can be determined, so that after the first terminal is switched to the second network, the data of the multicast service can be received through the EPS bearer, the continuity of service transmission is ensured, and meanwhile, the utilization rate of transmission resources is improved.

In one possible design, the method further includes: the first session management network element receives first indication information indicating that the multicast service is allowed to be switched to the second network. Illustratively, the first session management network element acquires a first PCC rule, where the first PCC rule includes the first indication information.

Based on the possible design, the first session management network element may obtain the first indication information from other network elements, and may effectively and flexibly indicate whether to allow the multicast service to be switched to the second network.

In one possible design, the determining, by the first session management network element, the context of the EPS bearer corresponding to the multicast service includes: the first session management network element acquires a first PCC rule corresponding to the multicast service and including QoS parameters of at least one service data flow SDF corresponding to the multicast service when the application server sends the multicast service in a multicast mode, and maps the at least one SDF to the at least one EPS bearer according to the QoS parameters of the at least one SDF.

Based on the possible design, the first session management network element may obtain the first PCC rule when establishing the multicast session corresponding to the multicast service, and determine the context of the EPS bearer corresponding to the multicast service according to the first PCC rule, which is simple and easy.

In one possible design, the determining, by the first session management network element, the context of the EPS bearer corresponding to the multicast service includes: the first session management network element maps at least one QoS flow corresponding to the multicast service to at least one EPS bearer according to the QoS flow information of the multicast service; the QoS flow information comprises QoS parameters of at least one QoS flow, and the at least one QoS flow is used for transmitting data of multicast service in a multicast mode by an application server.

Based on the possible design, the first session management network element can acquire the QoS flow information of the multicast service, and determine the context of the EPS bearer corresponding to the multicast service according to the QoS flow information of the multicast service, so that the method is simple and easy to implement.

In one possible design, the method further includes: the first session management network element acquires QoS flow information of the multicast service from a second session management network element which manages the multicast service.

Based on the possible design, the first session management network element can acquire the QoS stream information of the multicast service from the second session management network element which manages the multicast service, and the system design is simplified.

In one possible design, the determining, by the first session management network element, the context of the EPS bearer corresponding to the multicast service includes: and the first session management network element maps at least one Service Data Flow (SDF) corresponding to the multicast service to at least one EPS bearer according to a second PCC rule of the QoS parameter of the SDF corresponding to the multicast service when the application server sends the multicast service in a unicast mode.

Based on the possible design, the first session management network element can determine the context of the EPS bearer according to the PCC rule when the multicast service is sent in the unicast mode, so that the determined EPS bearer meets the QoS parameter for sending the multicast service in the unicast mode, and the method is simple and easy to implement.

In one possible design, the method further includes: and the first session management network element sends a first event notice for informing the first terminal to join the multicast session corresponding to the multicast service to the application server, and receives the second PCC rule.

Based on the possible design, the first session management network element notifies the application server of the fact that the first terminal joins in the multicast session, so that the application server sends second description information corresponding to the terminal joining in the multicast session to the first network element, the policy control network element further determines a second PCC rule according to the second description information, the first session management network element receives the second PCC rule and determines context information of an EPS bearer corresponding to the multicast service related to the terminal, so that switching of the multicast service to the second network is possible, and continuity of multicast service transmission is ensured.

In one possible design, the method further includes: the first session management network element receives a first subscription request for requesting to notify an application server of a first event, wherein the first event is that a terminal joins in a multicast session corresponding to a multicast service, and the terminal comprises a first terminal.

Based on the possible design, the first session management network element may receive a subscription request for subscribing to the first event, and send a notification of the first event to the application server under the subscription request, thereby improving user experience.

In one possible design, the method further includes: and the first session management network element receives second indication information used for indicating that the first terminal is switched, and sends second information of a first mapping relation between identification information of the multicast service flow and tunnel information borne by the EPS to the first user plane network element, wherein the identification information of the multicast service flow is used for identifying the multicast service flow corresponding to the multicast service, and the first mapping relation is used for indicating the first user plane network element to send data of the multicast service through the EPS bearer.

Based on the possible design, the first session management network element may send the first mapping relationship between the identification information of the multicast service stream and the tunnel information of the EPS bearer to the first user plane network element after the first terminal is switched, so that, subsequently, after the application server sends the data packet of the data of the multicast service to the first user plane network element, the first user plane network element sends the received data to the SGW/target access network device through the corresponding EPS bearer according to the first mapping relationship.

In one possible design, the method further includes: and the first session management network element receives second indication information used for indicating that the first terminal is switched, and sends a second message comprising a second mapping relation between the identifier of the QoS flow and the tunnel information of the EPS bearer to the first user plane network element, wherein the second mapping relation is used for indicating the first user plane network element to send a data packet corresponding to the QoS flow through the EPS bearer.

Based on the possible design, the first session management network element may send, after the first terminal is switched, the second mapping relationship between the identifier of the QoS flow and the tunnel information of the EPS bearer to the first user plane network element, so that after the subsequent application server sends the data packet of the data of the multicast service to the second user plane network element, the second user plane network element sends the received data packet and the QFI together to the first user plane network element, and after the first user plane network element receives the data packet including the data of the multicast service transmitted through the tunnel, the data of the multicast service is sent to the SGW/target access network device through one or more EPS bearers according to the second mapping relationship, the QFI corresponding to the data packet, and the identifier of the EPS bearer.

In one possible design, the second message is further used to obtain downlink tunnel information of the first user plane network element, where the downlink tunnel information of the first user plane network element is used to establish a tunnel for transmitting data of the multicast service between the first user plane network element and the second user plane network element, and the second user plane network element is used to transmit the multicast service in the first network; the method further comprises the following steps: and the first session management network element sends the downlink tunnel information of the first user plane network element to the second user plane network element.

Based on the possible design, the downlink tunnel information of the first user plane network element can be acquired through the second message and sent to the second user plane network element, so that the system design is simplified and the signaling overhead is reduced.

In one possible design, the method further includes: and the first session management network element sends a second event notification to the application server, wherein the second event notification is used for notifying the first terminal of the completion of switching to the second network or the second network.

Based on the possible design, a second event notification may be sent to the application server when the first terminal is about to switch to the second network or switch to the second network is completed, so that after the application server receives the second event notification, the application server prepares to start sending a data packet of the multicast service to the first user plane network element in a unicast manner or a multicast manner, and sends a third message to the first terminal, the third message being used to notify the first terminal of receiving the data of the multicast service through the EPS bearer or to notify the first terminal of receiving the data of the multicast service through the unicast session. Therefore, preparation for sending the data of the multicast service in a unicast mode can be started in the process that the first terminal is switched from the first network to the second network, packet loss is avoided, and the continuity of data transmission after the first terminal is successfully switched to the second network is guaranteed.

In a possible design, the first session management network element is further configured to receive a second subscription request of the application server, where the second subscription request is used to request that the application server be notified of a second event, and the second event is that the first terminal is to be switched to the second network or that the switching to the second network is completed or that the first terminal is switched to the second network or during the switching of the first terminal to the second network.

Based on the possible design, the first session management network element can send the second event notification to the application server under the subscription request of the application server, so that the user experience is improved, and meanwhile, the switching condition of the terminal is timely notified to the application server, so that the application server can timely prepare for sending the data of the multicast service to the terminal, the packet loss is avoided, and the continuity of data transmission after the first terminal is successfully switched to the second network is ensured.

In one possible design, the method further includes: a first session management network element sends context information of EPS bearer to a source access network device; and/or the first session management network element sends an identifier of the EPS bearer, or the identifier of the EPS bearer and a packet filter of the EPS bearer to the first terminal.

Based on the possible design, the first session management network element may send information related to the EPS bearer to the source access network device and the first terminal, so that the source access network device and the first terminal accurately receive data of the multicast service sent by the application server according to the received information related to the EPS bearer, and reliability of multicast service transmission is improved.

In one possible design, the method further includes: the first session management network element receives third indication information used for indicating to stop sending the data of the multicast service to the first terminal through the EPS bearer or indicating to the first terminal to receive the data of the multicast service through the MBMS bearer, and sends first configuration information used for informing the first user plane network element to stop sending the data of the multicast service to the first terminal through the EPS bearer to the first user plane network element.

Alternatively, the method further comprises: and the first session management network element receives eighth indication information used for indicating to delete the EPS bearer or indicating that the first terminal receives the data of the multicast service through the MBMS bearer from the first terminal, and sends first configuration information used for informing the first user plane network element to stop sending the data of the multicast service to the first terminal through the EPS bearer to the first user plane network element according to the eighth indication information.

Based on the possible design, the first session management network element may send the first configuration information to the first user plane under the condition that the sending of the data of the multicast service to the first terminal through the EPS bearer is stopped, so that the first user plane network element stops sending the data of the multicast service to the first terminal through the EPS bearer, releases the transmission resource, and improves the utilization rate of the transmission resource.

In one possible design, the method further includes: and the first session management network element receives fourth indication information for indicating that the data of the multicast service is sent to the first terminal through the EPS bearer, and sends second configuration information for informing the first user plane network element of sending the data of the multicast service to the first terminal through the EPS bearer to the first user plane network element.

Based on the possible design, when the data of the multicast service is sent to the first terminal through the EPS bearer again, the second configuration information is sent to the first user plane network element, so that the first user plane network element sends the data of the multicast service to the first terminal through the EPS bearer, the sending mode of the multicast service is adjusted in time, and the reliability of data transmission is improved.

In a second aspect, the present application provides a communication apparatus, which may be a first session management network element or a chip or a system on a chip in the first session management network element, and may also be a module or a unit in the first session management network element for implementing the service switching method according to the embodiment of the present application, or another module or unit capable of implementing the method executed by the first session management network element. The communication means may implement the functions performed by the first session managing network element in the above-described first aspect or in each possible design. In one design, the communication device may include a module unit or means (means) corresponding to one for performing the method/operation/step/action described in the first aspect, and the module, unit or means may be implemented by hardware, software or hardware to perform corresponding software. The hardware or software includes one or more modules or units corresponding to the above functions.

In a third aspect, a communication apparatus is provided, which may be a first session management network element or a chip or a system on chip in the first session management network element, or another module or unit capable of implementing the first session management network element side method. The communication means may implement the functions performed by the first session managing network element in the above-mentioned first aspect or in each possible design, and the functions may be implemented by hardware. In one possible design, the communication device may include: a processor and a communications interface, the processor being operable to support a communications device to implement the functionality referred to in the first aspect above or in any one of the possible designs of the first aspect, for example: the processor is configured to receive, through the communication interface, a first message from the first mobility management network element for requesting context information of an EPS bearer corresponding to a PDU session, and send, according to the first message, the context information of the EPS bearer to the first mobility management network element through the communication interface, where the context information of the EPS bearer includes a context of the EPS bearer corresponding to the multicast service. In yet another possible design, the communication device may further include a memory to hold computer instructions and/or data. When the communication device is running, the processor executes the computer instructions stored in the memory to cause the communication device to perform the service switching method according to the first aspect or any one of the possible designs of the first aspect. In the embodiments of the present application, the communication interface may be a transceiver, an interface circuit, a bus interface, a pin, or other devices capable of performing a transceiving function.

In a fourth aspect, a computer-readable storage medium is provided, in which instructions are stored, which when run on a computer, enable the computer to perform the service switching method according to the first aspect or any possible design of the above aspect.

In a fifth aspect, a computer program product comprising instructions may be provided, the computer program product comprising program instructions that, when run on a computer, enable the computer to perform the service switching method of the first aspect or any possible design of the above aspect.

A sixth aspect provides a system on chip comprising a processor and a communication interface, where the system on chip may be configured to implement the functions performed by the first session managing network element in the first aspect or any possible design of the first aspect. For example, the processor is configured to receive, through the communication interface, a first message from the first mobility management network element for requesting context information of an EPS bearer corresponding to a PDU session, and send, according to the first message, the context information of the EPS bearer to the first mobility management network element through the communication interface, where the context information of the EPS bearer includes a context of the EPS bearer corresponding to the multicast service. In one possible design, the system-on-chip further includes a memory, where the memory is used to store program instructions and/or data, and when the system-on-chip is running, the processor executes the program instructions stored in the memory, so as to enable the system-on-chip to perform the service switching method according to the first aspect or any one of the possible designs of the first aspect. The chip system may be formed by a chip, and may also include a chip and other discrete devices, without limitation.

In a seventh aspect, an embodiment of the present application further provides a service switching method, where the method includes: the application server receives a first report from the first terminal for indicating the first terminal to enter an MBMS area of the multicast service in the second network, and sends fifth indication information for indicating to stop sending data of the multicast service to the first terminal through an EPS bearer in the second network to the first network element.

Based on the method described in the seventh aspect, when the first terminal enters the MBMS area of the multicast service in the second network, the application server may switch the mode of sending the data of the multicast service, and switch the EPS bearer to the MBMS bearer, so that the first terminal switches the reception of the multicast service of the first terminal from being received via the EPS bearer (i.e., unicast bearer) to being received via the MBMS bearer, and adjusts the sending mode of the multicast service in time, thereby ensuring the continuity of service transmission.

In one possible design, the method further includes: and the application server receives a second report of the first terminal, which is used for indicating that the first terminal moves out of the MBMS area of the multicast service, and sends sixth indication information, which indicates that the data of the multicast service is sent to the first terminal through EPS bearing.

Based on the possible design, when the terminal moves out of the MBMS area of the multicast service, the MBMS bearer is switched to the EPS bearer, so that the first terminal switches the multicast service of the first terminal from receiving through the MBMS bearer to receiving through the EPS bearer (i.e., unicast bearer), and adjusts the sending mode of the multicast service in time, thereby ensuring the continuity of service transmission.

In one possible design, the method further includes: the application server sends the data packet of the multicast service including the data of the multicast service and the multicast address of the multicast service to the first user plane network element through the EPS bearer, namely, the data of the multicast service is sent in a multicast mode, the sending mode does not need to be switched to a unicast mode, and the method is simple and easy to implement.

In one possible design, the method further includes: the application server sends first description information of the multicast service for formulating the first PCC rule to the first network element, wherein the first PCC rule comprises a QoS parameter of at least one service data flow SDF corresponding to the multicast service when the application server sends the multicast service in a multicast mode.

Based on the possible design, in the case that the data of the multicast service is sent in the multicast mode, the application server sends the first description information for formulating the first PCC rule, so that the context of the EPS bearer determined according to the first PCC rule meets the QoS parameter specified by the first description information, that is, the QoS parameter when the multicast mode is sent, and the experience that the terminal switches to the EPS bearer to receive the data of the multicast service is not affected.

In one possible design, the first description information includes first indication information for indicating that the multicast service is allowed to be switched to the second network, that is, whether the multicast service is allowed to be switched to the second network is indicated by the first description information, the design is simple, and signaling overhead is reduced.

In one possible design, the method further includes: and the application server sends a data packet of the multicast service comprising the data of the multicast service and the address information of the first terminal to the first user plane network element through the EPS bearer.

Based on the possible design, the application server can pointedly send the data of the multicast service to the first terminal in a unicast mode, and the utilization rate of transmission resources is improved.

In one possible design, the fifth indication information is further used to indicate the first network element to delete the second description information when the multicast service corresponding to the multicast service is transmitted through the unicast bearer, and the second description information is used to formulate a second PCC rule corresponding to the multicast service; the sixth indication information includes second description information.

Based on the possible design, when the terminal moves into the MBMS area of the multicast service, the second description information can be deleted through the fifth indication information, so that the resource utilization rate is improved; when the terminal moves out of the MBMS area of the multicast service and is switched to the EPS bearer to receive the data of the multicast service, the sixth indication information indicates the second description information to the first network element again so as to appoint the second PCC rule again according to the second description information, and the context of the EPS bearer is determined according to the second PCC rule, thereby ensuring the accuracy and the continuity of the multicast service transmission.

In one possible design, the method further includes: and after receiving a first event notification from the first network element for notifying the first terminal to join the multicast session corresponding to the multicast service, the application server sends second description information corresponding to the multicast service to the first network element. After the first terminal is informed to join the multicast session, sending the second description information so as to execute the second PCC rule according to the second description information, determining the EPS bearer according to the second PCC rule, and sending the data of the multicast service to the first terminal through the EPS bearer so as to ensure the continuity of the multicast service transmission.

In one possible design, the method further includes: the application server sends a first subscription request for requesting to notify the application server of a first event to a first network element, wherein the first event is that a terminal joins a multicast session corresponding to the multicast service, and the terminal comprises a first terminal.

In one possible design, the method further includes: and the application server receives a second event notification from the first session management network element for notifying the first terminal of the impending handover to the second network or the completion of the handover to the second network, and sends a third message for notifying the first terminal of receiving the data of the multicast service through the EPS bearer to the first terminal. Further, after receiving the second event notification, the application server starts to send a data packet of the multicast service, which includes data of the multicast service and address information of the first terminal.

Based on the possible design, the application server may start to prepare for sending data of the multicast service in a unicast manner when the first terminal is switched from the first network to the second network, so as to avoid packet loss and ensure continuity of data transmission after the first terminal is successfully switched to the second network.

In one possible design, the method further includes: and the application server sends a second subscription request for requesting to notify the application server of a second event to the first network element, wherein the second event is that the first terminal is about to be switched to the second network or the switching to the second network is completed.

In an eighth aspect, the present application provides a communication apparatus, where the communication apparatus may be an application server or a chip or a system on a chip in the application server, a module or a unit in the application server for implementing the data transmission method according to the embodiments of the present application, or another module or unit capable of implementing an application server side. The communication device may implement the functions performed by the application server in the seventh aspect or in every possible design, and in one design, the communication device may include one-to-one corresponding module unit or means for performing the method/operation/step/action described in the seventh aspect, and the module, unit or means may be implemented by hardware, software, or by hardware and corresponding software. The hardware or software includes one or more modules or units corresponding to the above functions.

In a ninth aspect, a communication device is provided, which may be an application server or a chip or a system on chip in the application server, or other modules or units capable of implementing the application server side. The communications apparatus may implement the functions performed by the application server in the seventh aspect or in each possible design, which functions may be implemented by hardware. In one possible design, the communication device may include: a processor and a communication interface, the processor being operable to support a communication device to implement the functionality involved in any one of the possible designs of the seventh aspect or the seventh aspect. For example: the processor is configured to receive, through the communication interface, a first report from the first terminal, the first report being used to instruct the first terminal to enter an MBMS area of a multicast service in the second network, and send, to the first network element, fifth indication information used to instruct to stop sending data of the multicast service to the first terminal through an evolved packet system, EPS, bearer in the second network. In yet another possible design, the communication device may further include a memory to hold computer instructions and/or data. When the communication device is operating, the processor executes the computer instructions stored in the memory to cause the communication device to perform the data transmission 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 data transmission method of the seventh aspect or any one of the possible designs of the aspects.

In an eleventh aspect, there is provided a computer program product comprising instructions, the computer program product may include program instructions, which when run on a computer, cause the computer to perform the data transmission method of the seventh aspect described above or any possible design of the above aspect.

In a twelfth aspect, a chip system is provided, where the chip system includes a processor and a communication interface, and the chip system may be configured to implement the functions performed by the application server in any possible design of the seventh aspect or the seventh aspect. For example, the processor is configured to receive, through the communication interface, a first report from the first terminal for instructing the first terminal to enter an MBMS area of the multicast service in the second network, and send, to the first network element, fifth indication information for instructing to stop sending data of the multicast service to the first terminal through an evolved packet system, EPS, bearer in the second network. In one possible design, the chip system further includes a memory, where the memory is used to store program instructions and/or data, and when the chip system runs, the processor executes the program instructions stored in the memory, so as to enable the chip system to execute the data transmission method according to any one of the possible designs of the seventh aspect or the seventh aspect. The chip system may be formed by a chip, and may also include a chip and other discrete devices, without limitation.

In a thirteenth aspect, the present application further provides a communication system, where the communication system includes the communication apparatus according to the second aspect or the third aspect, and the communication apparatus according to the eighth aspect or the ninth aspect.

Drawings

Fig. 1a is an architecture diagram of a communication system according to an embodiment of the present application;

fig. 1b is a schematic architecture diagram of another communication system according to an embodiment of the present application;

fig. 2 is a schematic diagram of an architecture for interworking between a 4G network and a 5G network according to an embodiment of the present application;

fig. 3 is a schematic diagram illustrating a communication device 300 according to an embodiment of the present disclosure;

fig. 4 is a flowchart of a service switching method according to an embodiment of the present application;

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

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

fig. 7 is a flowchart of another service switching method according to an embodiment of the present application;

fig. 8 is a schematic diagram illustrating a communication device 80 according to an embodiment of the present disclosure;

fig. 9 is a schematic composition diagram of a communication device 90 according to an embodiment of the present disclosure.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Where in the description of the present application, "/" indicates a relationship where the objects associated before and after are an "or", unless otherwise stated, 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 alone, A and B exist simultaneously, and B exists alone, 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, terms such as "first" and "second" are used to distinguish the same items or similar items having substantially the same functions and actions. Those skilled in the art will appreciate that the terms "first," "second," etc. do not denote any order or quantity, nor do the terms "first," "second," etc. denote any order or importance. Also, in the embodiments of the present application, words such as "exemplary" or "for example" are used to mean serving as examples, illustrations or illustrations. Any embodiment or design described herein as "exemplary" or "e.g.," 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.

In addition, the network architecture and the service scenario described in the embodiment of the present application are for more clearly illustrating the technical solution of the embodiment of the present application, and do not constitute a limitation to the technical solution provided in the embodiment of the present application, and it can be known by a person skilled in the art that the technical solution provided in the embodiment of the present application is also applicable to similar technical problems along with the evolution of the network architecture and the appearance of a new service scenario.

The service switching method provided by the embodiment of the application can be applied to a communication system in which a first network and a second network are communicated with each other, so that the multicast service transmitted in the first network is switched to a transmission channel in the second network for transmission. In this application, the multicast service may be a multicast type service, or a broadcast type service, such as a broadcast service, and is not limited.

As shown in fig. 1a, for a communication system 10 provided in the embodiment of the present application, the communication system 10 is a communication system in which a first network and a second network are intercommunicated, and the communication system 10 includes a first mobility management network element and a first session management network element. Further, the method may further include a first user plane network element, a second mobility management network element, or an application server. The first mobility management network element is located in a first network, the first session management network element and the first user plane network element are shared network elements/co-located network elements of the first network and a second network, and the second mobility management network element is located in the second network. The application server is located in a Data Network (DN).

The first mobility management element is configured to send a first message requesting context information of an EPS bearer corresponding to a Protocol Data Unit (PDU) session to the first session management element. The first session management network element is configured to receive a first message, which is sent by the first mobility management network element and used to request context information of an EPS bearer corresponding to a Protocol Data Unit (PDU) session, and send the context information of the EPS bearer to the first mobility management network element according to the first message, so that the first mobility management network element triggers the second mobility management network element to establish the EPS bearer according to the context information of the EPS bearer.

The first mobility management network element is specifically configured to send a first message to the first session management network element when receiving a handover request for indicating that the first terminal is handed over.

Further, the first session management network element is further configured to obtain the first PCC rule, and map the at least one SDF to the at least one EPS bearer according to the QoS parameter of the at least one SDF included in the first PCC rule; or acquiring QoS flow information of a multicast service, and mapping at least one QoS flow corresponding to the multicast service to the at least one EPS bearer according to the QoS flow information of the multicast service; or acquiring a second PCC rule, and mapping at least one SDF to at least one EPS bearer according to the QoS parameter of at least one SDF included in the second PCC rule.

Further, the first session management network element is further configured to send a second event notification to the application server, where the second event notification is used to notify the first terminal that the data of the multicast service is received through or is going to be received through an EPS bearer, or the second event notification is used to notify the first terminal that the switching to the second network is going to be performed or the switching to the second network is completed, or the second event notification is used to notify the application server that the first terminal receives the data of the multicast service through a unicast session. And the application server is used for receiving the second event notification and sending a third message to the first terminal according to the second event notification, wherein the third message is used for notifying the first terminal to receive the data of the multicast service through the EPS bearer.

Further, the first session management network element is further configured to receive a second subscription request of the application server, where the second subscription request is used to request that the application server be notified of a second event, and the second event is that the first terminal is to be switched to the second network or that the switching to the second network is completed or that the first terminal is in the process of being switched to the second network.

Further, the application server is further configured to start sending a data packet of the multicast service after receiving the second event notification, where the data packet includes data of the multicast service and a destination address, and the destination address includes address information of the first terminal.

Based on the communication system shown in fig. 1a, the first session management network element may determine context information of an EPS bearer, where the context information of the EPS bearer includes a context of an EPS bearer corresponding to the multicast service, and when the first terminal is switched, send the context information of the EPS bearer to the first mobility management network element, so that the first mobility management network element triggers other network elements to establish a tunnel of the EPS bearer, so that when the first terminal is switched to the second network, the application server sends data of the multicast service to the first terminal through the EPS bearer, and ensures continuity of multicast service transmission.

Further, as shown in fig. 1b, the communication system 10 may further include: a first terminal, a source access network device, a second session management network element, a second user plane network element, a multicast/multicast service controller, a multicast/multicast gateway, a Serving Gateway (SGW), a second mobility management network element, and a first network element: network storage network elements, policy control network elements, network open function network elements, and the like. Taking the first terminal as the terminal 1 as an example, in the system shown in fig. 1b, a transmission path for transmitting data of the multicast service in the first network may be referred to as a multicast session, and a transmission path corresponding to the multicast session may be: the application server comprises a first user plane network element and a plurality of terminals including a terminal 1; or, the application server < second user plane network element < first user plane network element < source access network equipment < comprises a plurality of terminals including the terminal 1. The transmission path used for transmitting the data of the multicast service in the second network may include an EPS bearer and an MBMS bearer, and the transmission path of the EPS bearer is: an application server < a first user plane network element < a service gateway < a target access network device < a terminal 1. The transmission path corresponding to the MBMS bearer is as follows: an application server multicast/multicast service controller multicast/multicast gateway target access network equipment terminal 1. In the system shown in fig. 1b, the transmission path of signaling interaction between the terminal and the application server in the second network is: an application server < a first user plane network element < a source access network device < a terminal 1.

Further, in the communication system shown in fig. 1b, the application server is further configured to receive a first report from the first terminal, where the first report is used to instruct the first terminal to enter a multicast/multicast media service (MBMS) area of the multicast service in the second network, where the first terminal may receive data of the multicast service through an MBMS bearer; and sending fifth indication information to the first network element, wherein the fifth indication information is used for indicating to stop sending the data of the multicast service to the first terminal through an Evolved Packet System (EPS) bearer in the second network or indicating to receive the data of the multicast service through a bronze drum Multimedia Broadcast Multicast Service (MBMS) bearer of the first terminal.

Further, the first session management network element is further configured to receive a request message for adding the first terminal to a multicast session corresponding to the multicast service, and in a process of adding the first terminal to the multicast session corresponding to the multicast service, obtain a first Policy and Charging Control (PCC) rule corresponding to the multicast service from the policy control network element, determine a context of an EPS bearer corresponding to the multicast service according to the first PCC rule, or obtain QoS flow information corresponding to the multicast service from the second session management network element, determine the context of the EPS bearer corresponding to the multicast service according to a quality of service (QoS) flow corresponding to the multicast service, or obtain a second PCC rule from the policy control network element, and determine the context of the EPS bearer corresponding to the multicast service according to the second PCC rule.

Further, the QoS flow information corresponding to the first PCC rule and/or the multicast service includes first indication information, where the first indication information is used to indicate that the multicast service is allowed to be switched to the second network.

Further, the application server is further configured to send first description information to the first network element, where the first description information includes first indication information, so that the policy control network element obtains the first description information and formulates the first PCC rule.

Further, the first session management network element is further configured to send a first event notification to the application server in a process that the first terminal joins in a multicast session corresponding to the multicast service, and the application server is further configured to send second description information to the first network element after receiving the first event notification, so that the policy control network element obtains the second description information to formulate a second PCC rule.

Optionally, the terminal device in this embodiment may be a device for implementing a wireless communication function, for example, a terminal or a chip that can be used in the terminal. Among them, the terminal may be a User Equipment (UE), an access terminal, a terminal unit, a terminal station, a mobile station, a distant station, a remote terminal, a mobile device, a wireless communication device, a terminal agent, a terminal device, or the like in a 5G network or a future-evolution communication system. An access terminal may be a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device having wireless communication capabilities, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, or a wearable device, a Virtual Reality (VR) terminal device, an Augmented Reality (AR) terminal device, a wireless terminal in industrial control (industrial control), a wireless terminal in self driving (self driving), a wireless terminal in remote medical (remote medical), a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city (smart city), a wireless terminal in smart home (smart home), and the like. The terminal may be mobile or stationary.

Optionally, the source access network device and the target access network device in the embodiment of the present application are mainly used for implementing functions such as a physical layer function, resource scheduling and management, access control of a terminal, and mobility management. The source access network device and the target access network device may be devices supporting wired access or devices supporting wireless access. Illustratively, the source access network device may be a next generation radio access network (NG-RAN) device, AN Access Network (AN)/Radio Access Network (RAN), and is composed of a plurality of 5G-AN/5G-RAN nodes. The 5G-AN/5G-RAN node may be: a next generation base station (NR nodeB, gNB), a Transmission Reception Point (TRP), a Transmission Point (TP), or some other access node, etc. The target access network device may be an evolved universal terrestrial radio access network (E-UTRAN) device, such as an Access Point (AP), a base station (nodeB, NB), an enhanced base station (eNB), or some other access node.

Optionally, the mobility management network element in the embodiment of the present application is mainly responsible for access authentication of the terminal, mobility management, signaling interaction between functional network elements, and the like, for example: 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.

Optionally, the session management network element in this embodiment of the present application is mainly used to implement a user plane transmission logical channel, for example: and session management functions such as establishment, release and change of PDU sessions.

Optionally, the user plane network element in this embodiment of the present application may be used as an anchor point on a user plane transmission logical channel, and is configured 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 a data message of the terminal, forwarding data, controlling the rate and generating charging information.

Optionally, the network element with a network open function in the embodiment of the present application may be used to open events and capabilities of a core network, translate external parameters and internal parameters of the core network, receive and store information provided by the external network element of the core network, and perform functions such as core network device selection. The network element outside the core network may include an application server and the like.

Optionally, the policy control network element in this embodiment of the present application may be configured to provide a policy to a mobility management network element and a session management network element, where the policy control network element includes: quality of service (quality of service) policies, slice selection policies, and the like.

Optionally, the network storage network element in this embodiment of the present application may be used to store user data, such as: subscription information, authentication or authorization data, etc. of the user. The network storage network element may be a Unified Data Management (UDM), a network storage function (NRF), a Unified Data Repository (UDR), or the like.

Optionally, the serving gateway and the multicast/multicast gateway (MBSC-GW) in this embodiment of the present application may perform routing and forwarding of a data packet under the control of the second mobility management network element, that is, forward the received user data to a specified network element. The serving gateway may be deployed in the communication system independently as shown in fig. 1b, or may be integrated in other network elements, for example, the user plane function of the serving gateway is integrated in the first user plane network element, and the data plane function of the serving gateway is integrated in the first session management network element, which is not limited.

Optionally, the multicast/multicast service controller (MBSC) in the embodiment of the present application has service management functions such as group management, security management, and service announcement.

Optionally, the DN in this embodiment may provide an operator network of a data transmission service for a user, such as: an operator network or the like that provides IP Multimedia Services (IMS) to users may be provided. An Application Server (AS) may be deployed in the DN, and may provide data transmission services to users.

It should be noted that fig. 1b is only an exemplary architecture diagram, and besides the functional units shown in fig. 1b, 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. 1b are not limited, and in addition to the names shown in fig. 1b, the devices may also be named by other names, such as network element names with the same or similar functions instead, without limitation.

In fig. 1a and 1b, the first network and the second network are different communication networks, and the two networks support different Radio Access Technologies (RATs), such as: the first network may be a fifth generation (5G) network or a New Radio (NR) network, and the first network may support a New Radio (NR) technology. The second network may be a Long Term Evolution (LTE) network or a fourth generation (4th generation, 4G) network, and the second network may support Long Term Evolution (LTE) technology, and the like. The following describes the communication system with reference to fig. 2, where the first network is a 5G network and the second network is a 4G network.

As shown in fig. 2, for a communication system in which a 5G network and a 4G network are intercommunicated, a network element corresponding to a first user plane network element may be a Packet Data Network (PDN) gateway user plane function (PGW-U) + UPF, and a network element corresponding to a first session management network element may be a PDN gateway control plane function (PGW-C) + SMF. The network element or entity corresponding to the second session management network element may be a Session Management Function (SMF) 1, the network element or entity corresponding to the second user plane network element may be a User Plane Function (UPF) 1, the network element or entity corresponding to the source access network device may be a gNB, the network element or entity corresponding to the target access network device may be an eNB, the network element or entity corresponding to the first mobility management network element may be an access and mobility management function (AMF), the network element or entity corresponding to the second mobility management network element may be a Mobility Management Entity (MME), the policy control network element may be a Policy Control Function (PCF), the network element or entity corresponding to the network open function network element may be a network open function (NEF), the network element or entity corresponding to the network slice selection network element may be a network slice selection function (network slice selection function), and the network element or entity corresponding to the network storage network element may be an NRF, an UDR, or an UDM. Here "+" indicates a convergence, for example, in PGW-U + UPF, UPF is the user plane function of the first network, and PGW-U is the gateway user plane function with the second network; in PGW-C + SMF, SMF is a session management function of a first network, and PGW-C is a gateway control plane function in a second network corresponding to the SMF. In the embodiment of the present application, the combined network device may also use other names, and this is not specifically limited in the embodiment of the present application.

Optionally, the first session management network element and the application server in this embodiment may also be referred to as a communication device, which may be a general device or a special device, and this is not specifically limited in this embodiment of the present application.

Optionally, related functions of the first session management network element or the application server in this embodiment of the present application may be implemented by one device, or may be implemented by multiple devices together, or may be implemented by one or more functional modules in one device, which is not specifically limited in this embodiment of the present application. It is understood that the above functions may be network elements in a hardware device, or software functions running on dedicated hardware, or a combination of hardware and software, or virtualization functions instantiated on a platform (e.g., a cloud platform).

In a specific implementation, the devices in the communication system shown above are: the first session managing network element, the application server, etc. may all adopt the composition structure shown in fig. 3 or include the components shown in fig. 3. Fig. 3 is a schematic diagram of a communication device 300 according to an embodiment of the present disclosure, where the communication device 300 may include a processor 301, a communication line 302, and a communication interface 303. Further, the communication device 300 may further include a memory 304. The processor 301, the memory 304 and the communication interface 303 may be connected by a communication line 302.

The processor 301 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 301 may also be other devices with processing functions, such as, without limitation, a circuit, a device, or a software module.

A communication line 302 for transmitting information between the respective components included in the communication apparatus 300.

A communication interface 303 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. Communication interface 303 may be a module, circuitry, transceiver, or any device capable of enabling communication.

A memory 304 for storing instructions. Wherein the instructions may be a computer program.

The memory 304 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 should be noted that the memory 304 may exist independently from the processor 301, or may be integrated with the processor 301. The memory 304 may be used for storing instructions or program code or some data or the like. The memory 304 may be located inside the communication device 300 or outside the communication device 300, which is not limited.

The processor 301 is configured to execute the instructions stored in the memory 304 to implement the service switching method provided by the following embodiments of the present application. For example, when the communication apparatus 300 is a session management network element or a chip or a system on chip in the session management network element, the processor 301 executes instructions stored in the memory 304 to implement the steps performed by the session management network element in the embodiments described below in the present application. For another example, when the communication apparatus 300 is a mobility management network element or a chip or a system on chip in the mobility management network element, the processor 301 may execute instructions stored in the memory 304 to implement the steps performed by the mobility management network element in the embodiments described below in the present application.

In one example, the processor 301 may include one or more CPUs, such as CPU0 and CPU1 in fig. 3.

As an alternative implementation, the communication device 300 may comprise a plurality of processors, for example, the processor 307 may be included in addition to the processor 301 in fig. 3.

As an alternative implementation, the communication apparatus 300 further includes an output device 305 and an input device 306. Illustratively, the input device 306 is a keyboard, mouse, microphone, or joystick-like device, and the output device 305 is a display screen, speaker (spaker), or like device.

It should be noted that the communication apparatus 300 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. 3. Further, the constituent structure shown in fig. 3 does not constitute a limitation of the communication apparatus, and the communication apparatus may include more or less components than those shown in fig. 3, or combine some components, or a different arrangement of components, in addition to the components shown in fig. 3.

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

The service switching method provided in the embodiment of the present application is described below with reference to the communication system shown in fig. 1 b. Each network element in the following embodiments may have the components shown in fig. 3, which are not described in detail. It should be noted that, the actions, terms and the like related to the embodiments of the present application may be mutually referred to, 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. For example: the multicast described in the embodiments of the present application may be replaced by the terms broadcast, multicast communication, multicast/broadcast, and the like. 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", the "stopping" in the present application may also be understood as "no longer" or "about to be impossible", the multicast service in the present application may also be replaced by a group service or a broadcast service, etc., which are all described herein, and the embodiment of the present application is not specifically limited to this.

Fig. 4 is a flowchart of a service switching method according to an embodiment of the present application, where the method describes a process of switching a multicast service transmitted through a PDU session in a first network to an EPS bearer in a second network. As shown in fig. 4, the method includes:

s401: the first terminal establishes a PDU session for the first terminal.

The first terminal may be any terminal supporting multicast service transmission in the communication system shown in fig. 1b, or may alternatively be any terminal described as the first terminal may be any terminal of a multicast group corresponding to the multicast service. In this application, a PDU session of the first terminal may be referred to as a unicast PDU session, and the first terminal may perform data transmission or signaling transmission with the application server through the PDU session. The anchor point of the PDU session or the user plane network element corresponding to the PDU session may be a first user plane network element, and the session management network element corresponding to the PDU session is a first session management network element, that is, the PDU session may be served by the first session management network element, for example, the first session management network element provides services such as PDU session establishment, PDU session modification, and PDU maintenance. For example, assuming that the first terminal is terminal 1, in the communication system shown in fig. 1b, the transmission path of the PDU session is: an application server < a first user plane network element < a source access network device < a terminal 1; in the communication system shown in fig. 2, the transmission path of the PDU session is: AS < - > PGW-U + UPF < - > gNB < - > terminal 1. On a transmission path of the PDU session, one or more intermediate UPF network elements (I-UPFs) may be further inserted between the source access network device (or PGW-U + UPF) and the source access network device (or gNB), which is not limited in this embodiment.

Specifically, the first terminal may be registered in the first network through the first mobility management network element, and after the first terminal is registered in the first network, a PDU session establishment request (PDU session initiation request) for establishing a PDU session is sent to the first mobility management network element, and after the first mobility management network element receives the PDU session establishment request, the first mobility management network element selects the first session management network element, and sends the PDU session establishment request to the first session management network element; after receiving the PDU session establishment request, the first session management network element determines quality of service (QoS flow, QF), selects the first user plane network element as the anchor point of the PDU session, and establishes the PDU session. Specifically, the detailed process of establishing the PDU session may refer to the prior art, and is not described in detail.

Further, after the first terminal successfully establishes the PDU session, the first mobility management network element may store a correspondence between the identification information of the PDU session and the identification information of the first session management network element. The first session management network element may store a correspondence between the identification information of the PDU session and the identification information of the first user plane network element, for example: and storing the corresponding relation between the identification information of the PDU conversation and the identification information of the first user plane network element in the context of the PDU conversation.

The identification information of the PDU session may be used to identify the PDU session, and the identification information of the PDU session may be an Identifier (ID) of the PDU session. The identification information of the PDU session can be configured by the first terminal, and the identification information of the PDU session is carried in the PDU session establishment request and is sent to the first mobility management network element and other core network devices.

Wherein the identification information of the first session management network element may be used to identify the first session management network element. For example, the identification information of the first session management network element may be an Internet Protocol (IP) address of the first session management network element, a Media Access Control (MAC) address of the first session management network element, a Fully Qualified Domain Name (FQDN) of the first session management network element, or another identifier capable of identifying the first session management network element, without limitation.

The first user plane network element may be referred to as a user plane network element corresponding to a PDU session, or may be described as a UPF, directly connected to the DN, for transmitting data of the first terminal, or may be described as a UPF for receiving data of the first terminal sent by the application server, or may be described as a UPF for transmitting a data transmission N6 interface endpoint of the first terminal, or may be described as an entry network element for receiving data of the first terminal on the core network user plane. The identification information of the first user plane network element may be used to identify the first user plane network element. For example, the identification information of the first user plane network element may be an IP address of the first user plane network element, a MAC address of the first user plane network element, or an FQDN of the first user plane network element, or may be another identifier capable of identifying the first user plane network element, which is not limited.

S402: and the first terminal joins the multicast session corresponding to the multicast service.

The multicast service may be directed to a plurality of terminals (two or more terminals), and the data receiving object of the multicast service may be two or more terminals. Such as: when a multicast service can be directed to multiple terminals in a group, all terminals in the group can be authorized to receive data of the multicast service, and the group of the multicast service can be a combination of multiple terminals receiving data of the same multicast service, such as: the group of multicast services may be a fleet of vehicles receiving commands issued by the same command center or a group of users receiving the same television program, etc. When the multicast service is a broadcast service, the data of the broadcast service can be sent to a plurality of terminals in a broadcast mode, and at the moment, the plurality of terminals receiving the data of the broadcast service can receive the data of the multicast service without authorization.

The multicast session may be referred to as a multicast PDU session or a multicast broadcast session, and the multicast session may be a logical channel for transmitting data of a multicast service, and the data of the multicast service may be sent to terminals in a multicast group through the multicast session. The transmission path of the multicast session may include a transmission path between a user plane network element corresponding to the multicast session and the source access network device, and may also include a transmission path between the source access network device and the first terminal. The multicast session may be served by a multicast session management network element, for example, the multicast session management network element selects a user plane network element corresponding to the multicast session to complete establishment, modification, maintenance, and the like of the multicast session.

In this application, the multicast session management network element for managing the multicast service may be a first session management network element or a second session management network element, and the first session management network element is different from the second session management network element. Such as: if the first session management network element has the function of managing the multicast service, the first session management network element can be used as a session management network element corresponding to the multicast session; if the first session management network element does not have the capability of managing the multicast service and the second session management network element has the function of managing the multicast service, the second session management network element can be used as the session management network element corresponding to the multicast session. The anchor point of the multicast session or the user plane network element corresponding to the multicast session may be a first user plane network element or a second user plane network element, and the first user plane network element is different from the second user plane network element. Such as: if the first user plane network element has a function of transmitting data of the multicast service (for example, the first user plane network element may directly acquire the data of the multicast service from the application server), the first user plane network element may be used as an anchor point of the multicast session, and if the first user plane network element does not have the function of transmitting the data of the multicast service, the second user plane network element may be used as an anchor point of the multicast session.

For example, assuming that the first terminal is terminal 1, if the first user plane network element has a function of transmitting data of a multicast service, in the communication system shown in fig. 1b, the transmission path of the multicast session is: an application server < - > a first user plane network element < -a source access network device < -a terminal, where the terminal includes a terminal 1, and in the system shown in fig. 2, a transmission path of the multicast session is: AS < - > PGW-U + UPF < - > gNB < - > terminal, which includes terminal 1. If the first user plane network element cannot directly receive the data of the multicast service from the AS, and the second user plane network element can directly receive the data of the multicast service from the AS, in the communication system shown in fig. 1b, the transmission path of the multicast session is: an application server < second user plane network element < source access network equipment < terminal, the terminal comprises a terminal 1; in the system shown in fig. 2, the transmission path of the multicast session is: AS < - > UPF1< - > gNB < - > terminal, including terminal 1. It should be noted that, in the embodiments of the present application, an intermediate user plane network element may also exist on a transmission path of a multicast session. For example, the first user plane network element may also be inserted/deployed between the second user plane network element and the source access network device as an intermediate user plane network element, which is not limited.

It should be noted that, in each embodiment of the present application, a transmission tunnel may be established between the application server and the user plane network element corresponding to the multicast session, or the application server may directly send the data of the multicast service to the user plane network element corresponding to the multicast session in a multicast manner, which is not limited.

In one possible design, the first terminal may be added to the multicast session when the multicast session is established, for example, when the first terminal is the terminal that first joins the multicast session corresponding to the multicast service, the multicast session is not established before the first terminal joins the multicast session, and at this time, the first terminal may trigger the establishment of the multicast session and join the multicast session.

In the first mode, the first terminal may initiate a request for establishing a multicast session through the PDU session in S401, and join the multicast session. Specifically, the implementation may include:

and the first terminal sends a joining request for requesting to join the multicast session to a first session management network element corresponding to the PDU session, and the first session management network element receives the joining request, triggers the establishment of the multicast session and joins the first terminal to the multicast session corresponding to the multicast service. The establishment of the multicast session may be triggered by the first session managing network element and the first session managing network element may need to interact with the session managing network element managing the multicast traffic during the establishment of the multicast session. For example, if the session management network element that manages the multicast service is the second session management network element, the first session management network element selects/determines the second session management network element, and obtains corresponding information, for example, quality of service (QoS) flow information corresponding to the multicast session, from the second session management network element. Establishing the multicast session may include: a transmission path for the multicast session is established.

As described above, the transmission path of the multicast session may include a path from the user plane network element corresponding to the multicast session to the source access network device, and taking fig. 1b as an example, the user plane network element corresponding to the multicast session is the second user plane network element, that is, the transmission path of the multicast session is a path between the second user plane network element and the source access network device. Establishing a transmission path between the second user plane network element and the source access network device requires acquiring tunnel information of the source access network device, and configuring the tunnel information of the source access network device to the second user plane network element, so that the second user plane network element sends data of the multicast service to the source access network device by using the tunnel. The transmission path of the multicast session may further include a transmission path between the source access network device and the first terminal, and establishing the transmission path between the source access network device and the first terminal may include: and sending the QoS flow information of the multicast session to the source access network equipment, and requesting the source access network equipment to configure wireless resources for the first terminal so as to send the data of the multicast service from the source access network equipment to the first terminal.

In the embodiments of the present application, according to different methods for establishing a multicast session, functions of a first session management network element and a second session management network element are different. Taking a session management network element for managing the multicast service as a second session management network element as an example, in an implementation manner, a first session management network element sends a request message to the second session management network element to request to obtain QoS stream information of the multicast service, the second session management network element receives the request message, sends the QoS stream information of the multicast service to the first session management network element, the first session management network element sends the QoS stream information to the source access network device, and requests the source access network device to configure a wireless resource of the multicast session for the first terminal. In the method of this embodiment, the second session management network element further sends the first indication information when sending the QoS flow information to the first session management network element, or the QoS flow information includes the first indication information. It should be noted that, the second session management network element determines the QoS flow information of the multicast service according to the first PCC rule, the second session management network element obtains the first PCC rule from the PCF, and if the PCF sends the first PCC rule to the second session management network element when sending the first PCC rule, the second session management network element also sends the first indication information when sending the QoS flow information to the first session management network element. The first session management network element receives tunnel information corresponding to a multicast session from the source access network device, the first session management network element sends the tunnel information to the second session management network element, and the second session management network element configures the tunnel information to a user plane network element corresponding to the multicast session, that is, a second user plane network element.

In another implementation manner, the second session management network element sends QoS flow information of the multicast service to the source access network device, and directly receives tunnel information corresponding to the multicast session from the source access network device. The second session managing network element may trigger the above-mentioned process after receiving the above-mentioned request message sent by the first session managing network element. Or, the second session management network element may send the QoS flow information to the first session management network element after receiving the request message, and the first session management network element may be responsible for subsequently notifying the source access network device to configure the radio resource of the multicast session for the first terminal.

Of course, there may be other methods for establishing a multicast session, which is not limited in this application.

In addition, establishing the multicast session may further include: the session management network element for managing the multicast service selects the user plane network element of the multicast service, that is, the second user plane network element, and executes the following processes: it should be noted that the multicast service flow described in the embodiments of the present application may refer to one or more service flows corresponding to a multicast service, such as a Service Data Flow (SDF), for example.

If a tunnel manner is adopted between the AS and the second user plane network element, establishing the multicast session may further include: and the session management network element for managing the multicast service acquires the tunnel information of the second user plane network element and sends the tunnel information of the second user plane network element to the application server, and the application server receives and stores the tunnel information of the second user plane network element and establishes a transmission tunnel between the application server and the second user plane network element.

It should be noted that, if the first session management network element itself can manage the multicast service, and is a session management network element for managing the multicast service, the participation of the second session management network element is not required in the process of establishing the multicast session, that is, the first session management network element has the function of the second session management network element. At this time, the first session management network element acquires the first PCC rule corresponding to the multicast service. And the first PCC rule includes the first indication information, or the first session managing network element receives the first indication information while receiving the first PCC rule.

The process of selecting/determining the second session management network element by the first session management network element refers to the prior art and is not described in detail herein.

The join request may include identification information of the multicast service stream, identification information of the first terminal, and may also include identification information of the PDU session and other information, which is not limited. The identification information of the multicast service flow may be used to uniquely identify the multicast service, and the identification information of the multicast service flow may be configured by an application layer or an application server of the first terminal. The identification information of the multicast service flow may be a Temporary Mobile Group Identifier (TMGI) of a multicast session corresponding to the multicast service, or an Internet Protocol (IP) address of an application server providing the multicast service, or a service identifier (service ID) of the multicast service, or packet filter (packet filter) information of the multicast service, or a Service Data Flow (SDF) identification rule of the multicast service, or an ID of the multicast session for transmitting the multicast service.

Wherein the identification information of the first terminal may be used to identify the first terminal. The identification information of the first terminal may include an IP address of the first terminal or a MAC address of the first terminal or an International Mobile Subscriber Identity (IMSI) or a Globally Unique Temporary Identifier (GUTI), a user permanent identifier (SUPI), a General Public Subscriber Identifier (GPSI), etc. of the first terminal.

Illustratively, when the first terminal determines to join the multicast session, the first terminal sends a join request to a first session management network element corresponding to the PDU session. Wherein the determining, by the first terminal, to join the multicast session may include: the first terminal receives an instruction sent by a user to join a certain multicast session, selects the multicast service which the user is interested in from a locally stored multicast service list, and determines to join the multicast session corresponding to the multicast service. Such as: the first terminal can display the multicast service list to a user, the user can select the interested multicast service from the multicast service list through the man-machine interaction interface, and the first terminal determines to join the multicast session corresponding to the multicast service according to the selection result of the user.

The multicast service list may include information of one or more multicast services, such as service identifiers of the multicast services. The multicast service list may be pre-configured on the first terminal or dynamically configured to the first terminal by the network side. For example, assume that the multicast service list may include information of multicast sessions, such as: CCTV1, CCTV2, and so on, where the first terminal is a Set Top Box (STB) 1, the STB1 may display relevant information of these tv programs to the user, and the user may manually select a tv program that the user wants to watch, such as: the CCTV1 is selected and the selection result is transmitted to the STB1, and the STB1 transmits a join request carrying identification information of the CCTV1 to the first session management network element according to the selection result.

Wherein, the sending, by the first terminal, the join request to the first session management network element corresponding to the PDU session may include the following first example or second example:

in an example, a first terminal sends a join request to a first session management network element through a user plane corresponding to a PDU session.

For example, the first terminal sends a join request to the source access network device through a PDU session, the source access network device receives the join request and sends the join request to the first user plane network element, and the first user plane network element receives the join request and sends the join request to the first session management network element. In an example one, the join request may be a user plane message.

In example two, the first terminal sends a join request to the first session management network element through the control plane corresponding to the PDU session.

For example, a first terminal sends a join request to a first mobility management network element; and the first mobility management network element receives the joining request and sends the joining request to the first session management network element according to the corresponding relation between the identification information of the PDU session in the context of the locally stored PDU session and the identification information of the first session management network element.

In example two, the join request may be a PDU session modification request (PDU session modification request), a PDU session establishment request, or other control plane signaling.

And the second mode is that the application server triggers the first terminal to join the multicast session. Specifically, the process may include:

the application server sends a message (A) for adding the first terminal into the multicast session to the first network element, and the first network element sends the message (A) to the policy control network element, wherein the policy control network element is a PCF corresponding to the PDU session of the first terminal. For example, the application server may send the message (a) to the NEF first, then to the UDR by the NEF, and to the PCF corresponding to the PDU session sent by the UDR to the first terminal. After receiving the message (a), the policy control network element requests the first session management network element to add the first terminal to the multicast session, and after receiving the request of the policy control network element, the first session management network element triggers the first session management network element to execute the establishment of the multicast session in the first mode or the second mode, which is not described in detail again.

Or, the application server sends a message (B) to the first network element to join the terminal to the multicast session, where the terminal includes the first terminal, for example, all terminals in the terminal list may be included. After receiving the message (B), the first network element may send the message (B) to policy control network elements corresponding to all terminals in the terminal list, for example: the application server may send the message (B) to the NEF first, and then the NEF sends the message to PCFs corresponding to all terminals in the terminal list. Taking the first terminal as an example, the message (B) is also sent to the PCF corresponding to the PDU session of the first terminal. After receiving the message (B), the PCF corresponding to the PDU session of the subsequent first terminal requests the first session management network element to execute the establishment of the multicast session in the above-mentioned manner one or manner two, and adds the first terminal into the multicast session, which is not described again.

In the above-mentioned first or second mode, the session management network element that manages the multicast service needs to determine QoS flow information of the multicast session. Specifically, the determining, by the session management network element for managing the multicast service, QoS flow information of the multicast session may include: the session management network element for managing the multicast service acquires a first Policy and Charging Control (PCC) rule from the policy control network element, and determines QoS flow information corresponding to the multicast service according to the acquired PCC rule. The process of determining the first PCC rule by the policy control network element is as follows:

an application server sends first description information of multicast service to a policy control network element (such as PCF); and the policy control network element receives the first description information and formulates a first PCC rule when the application server sends the data of the multicast service in a multicast mode according to the first description information of the multicast service. It should be noted that, the sending, by the application server, the first description information to the policy control network element may be directly sent to the policy control network element, or the application server sends the first description information to the policy control network element through another first network element, for example: the application server may send the first description information to the NEF, and the NEF may store the first description information in the UDR, and the PCF may obtain the first description information from the UDR or the UDR may push the first description information to the PCF.

The first description information of the multicast service is used to specify a transmission requirement when the application server sends the data of the multicast service in a multicast manner, and the first description information of the multicast service may include: when the application server sends the information of one or more Service Data Flows (SDFs) of the multicast service in a multicast manner, and the quality of service (QoS) requirements (such as bandwidth requirements, delay requirements, error rate, and the like) corresponding to the service data flows. In addition, the first description information may further include: communication area, start transmission time and/or end transmission time of data of multicast service transmitted by multicast mode, and address information of application server. If the multicast service supports switching to the second network (for example, 4G), the first description information further includes first indication information, and the first indication information may be used to indicate a service support condition of the multicast service (for example, whether to allow the multicast service to be switched to the second network, or the like).

The first PCC rule may include at least one SDF corresponding to the multicast service when the application server sends the multicast service in a multicast manner, and QoS parameters (e.g., bandwidth size, delay budget, error rate, etc.) of each SDF, and if the first description information includes the first indication information, the first PCC rule may further include the first indication information and other information, which is not limited. Specifically, the related description of the first PCC rule may refer to the prior art, and is not repeated. The QoS flow information determined according to the first PCC rule may include an identification of one or more quality of service flows (QFs), QoS parameters per QF, and the like. The identification of QF may be a fifth generation QoS flow identification (5G QoS flow identifier, 5QI), a fifth generation QoS identification (5G QoS ID), etc., without limitation. One or more SDFs corresponding to the multicast service may correspond to one QF, and the QoS parameter of the QF may be determined according to the QoS parameter of the one or more SDFs corresponding to the QF, such as: the value of the QoS parameter of QF may be equal to the sum of the values of the QoS parameters of one or more SDFs corresponding to QF. For example, assuming that the SDF corresponding to the multicast service 1 includes SDF1, SDF2, and SDF3, the session management network element managing the multicast service may map SDF1, SDF2 to QF1, and SDF3 to QF 2.

It should be noted that, in this embodiment of the application, if the first PCC rule or the first description information includes the first indication information, the session management network element that manages the multicast service further sends the first indication information when sending the QoS flow information of the multicast service to the first session management network element, or the session management network element that manages the multicast service includes the first indication information in the QoS flow information of the multicast service that is sent to the first session management network element.

It should be noted that, the present application is not limited to establishing the multicast session by the above-mentioned first method or the second method alone, and the multicast session may also be established by combining the first method and the second method, such as: a transmission tunnel between the application server and the second user plane network element can be established in a second mode, and a transmission tunnel between the source access network device and the second user plane network element is not established; subsequently, when the first terminal requests to establish the multicast session in the first mode, the establishment of the transmission tunnel between the source access network device and the second user plane network element is completed without establishing the transmission tunnel between the application server and the second user plane network element.

And at this point, successfully establishing the multicast session from the application server to the second user plane network element, from the second user plane network element to the source access network device, and from the source access network device to the first terminal, and successfully adding the first terminal into the multicast session. Subsequently, the application server may send the data of the multicast service to the second user plane network element according to the identification information of the second user plane network element, the second user plane network element receives and identifies the data of the multicast service sent by the application server, the data of the multicast service is sent to the source access network device through the QoS stream, and the source access network device sends the data of the multicast service to the first terminal joining the multicast session through the air interface transmission resource corresponding to the QoS stream information.

In yet another possible design, the multicast session is already established/established before the first terminal joins the multicast session, and at this time, the multicast session does not need to be established by performing the first manner and/or the second manner. In this case, corresponding to the first or second manner, as long as the source access network device is notified to allocate the radio resource corresponding to the multicast session to the first terminal, the description of the first or second manner may be specifically referred to.

Further optionally, after executing S402 or during executing S402, the network-side device may further notify the application server of the fact that the first terminal joins the multicast session. For example, in one implementation, the application server may send a first subscription request to the first network element, requesting that the application server be notified of a first event, the first event being that a terminal joins the multicast session, the terminal including the first terminal. Illustratively, the first subscription request may be sent to the first network element together with the first descriptive information (i.e. in one message). Subsequently, after the first terminal is added to the multicast session or during the first terminal is added to the multicast session in S402, the session management network element (e.g., the first session management network element or the second session management network element) may send a first event notification to the application server, where the first event notification is used to notify the application server that the first terminal is added to the multicast session. The first event notification may include identification information of the first terminal, such as an IP address of the first terminal. Further, the application server may further send second description information for formulating the second PCC rule to the first network element, and the first network element sends the second description information to the policy control network element, so that the policy control network element formulates the second PCC rule according to the second description information, and triggers the first session management network element to establish the context of the EPS bearer according to the second PCC rule. Thus, the application server can know which terminals are added to the multicast session, so that the application server sends second description information corresponding to the terminals added to the multicast session to the first network element, and the core network can further determine a second PCC rule according to the second description information and determine context information of an EPS bearer corresponding to the multicast service related to the terminal, so that it is possible to switch the multicast service to the second network.

The second description information and the description related to the second PCC rule may refer to those in S403. It should be noted that, in S402, when the application server sends the second description information to the policy control network element through the first network element, the application server may further instruct not to allocate the radio resource according to the second description information for the moment, that is, when the first terminal moves from the first network to the second network, the radio resource carried by the EPS is allocated according to the second PCC rule corresponding to the second description information. That is, the second description information is only used to formulate a second PCC rule, and trigger the core network device to determine the context information of the EPS bearer of the multicast service according to the second PCC rule, and the core network device does not really allocate the radio resource of the EPS bearer in the second network or the radio resource in the first network to the first terminal according to the second description information.

S403: and the first session management network element determines the context of the EPS bearer corresponding to the multicast service.

The EPS bearer may be a logical channel for transmitting data of the multicast service in the second network, and the context of the EPS bearer may include at least an identifier of at least one EPS bearer corresponding to the multicast service and QoS parameters of the EPS bearer, and may further include other information, such as downlink tunnel information of the first user plane network element, without limitation.

In an example, the first session management network element is a session management network element that manages a multicast service, and the first session management network element may determine, according to the first PCC rule, a context of an EPS bearer corresponding to the multicast service in a process of adding the first terminal to the multicast session. Such as: in the process that the first terminal joins in the multicast session, if the first session management network element determines that the multicast service is allowed to be switched to the second network, the first session management network element is triggered to determine the context of the EPS bearer corresponding to the multicast service according to the first PCC rule. It should be noted that, in this example, the first session management network element may be a session management network element that manages multicast services.

The first session management network element may determine, according to the first indication information, to allow the multicast service to be switched to the second network. The first indication information may be included in the first PCC rule, and the first session managing network element may obtain the first indication information from the first PCC rule. For example, the policy control network element may send the first indication information when sending the first PCC rule to the first session managing network element, i.e. send the first PCC rule and the first indication information to the first session managing network element in one message. Or, if the first PCC rule does not include the first indication information, the first session management network element may also obtain the first indication information from another place, such as: the first indication information may also be stored in the subscription information of the first terminal, and the first session management network element may obtain the first indication information from the subscription information of the first terminal. For example, the subscription information of the first terminal may include an identifier of a multicast service that is allowed to be switched, the identifier of the multicast service may be used to identify the multicast service, and the first session management network element may determine, according to the subscription information of the first terminal, to allow the multicast service to be switched to the second network, for example, if the identifier of the multicast service is included in the subscription information of the first terminal, to allow the multicast service to be switched to the second network.

In this application, allowing the multicast service to be switched to the second network may be alternatively described as that the multicast service may be transmitted through the first network or the second network, which is not limited.

Specifically, the determining, by the first session management network element according to the first PCC rule, the context of the EPS bearer corresponding to the multicast service may include: the first session management network element maps at least one SDF to at least one EPS bearer according to the QoS parameter of at least one SDF included in the first PCC rule, where one or more SDFs may be mapped to one EPS bearer, and at the same time, configures an identifier of an EPS bearer for each EPS bearer, and configures a value of the QoS parameter of each EPS bearer to be equal to a sum of values of QoS parameters of all SDFs corresponding to the EPS bearer.

For example, assuming that the SDF corresponding to the multicast service 1 includes SDF1, SDF2, and SDF3, the first session management network element may map SDF1 and SDF2 to EPS bearer 1 and map SDF3 to EPS bearer 2.

It should be noted that, in the above example, the first session managing network element acquires the first PCC rule. For example, when the first session management network element has the function of the second session management network element, the first session management network element may obtain the first PCC rule.

In another example, the first session management network element is not a session management network element for managing a multicast service, the second session management network element is a session management network element for managing a multicast service, and the first session management network element may determine, according to QoS flow information corresponding to the multicast service, a context of an EPS bearer corresponding to the multicast service in a process in which the first terminal joins in the multicast session. Such as: in the process that the first terminal joins in the multicast session, if the first session management network element determines that the multicast service is allowed to be switched to the second network, the first session management network element is triggered to determine the context of the EPS bearer corresponding to the multicast service according to the QoS flow information.

Wherein the first session managing network element may obtain the QoS flow information from the second session managing network element.

The first session management network element may determine, according to the first indication information, to allow the multicast service to be switched to the second network. For example, the first session management network element may obtain the first indication information from the second session management network element, for example, obtain the first indication information when obtaining the QoS flow information, or include the first indication information in the QoS flow information; alternatively, the first session managing network element may also obtain the first indication information from other network elements, such as: and acquiring the subscription information of the first terminal carrying the first indication information from other network elements, and determining that the multicast service is allowed to be switched to the second network according to the subscription information of the first terminal. In particular, reference is made to the description of one example above.

Specifically, the determining, by the first session management network element according to the QoS flow information, the context of the EPS bearer corresponding to the multicast service may include: the first session management network element maps one or more QoS flows to one or more EPS bearers according to the QoS flow information of the multicast service, the one or more QoS flows can be mapped to one EPS bearer, meanwhile, an EPS bearer identifier is configured for each EPS bearer, and the value of the QoS parameter of each EPS bearer is configured to be equal to the sum of the values of the QoS parameters of all QoS flows corresponding to the EPS bearer. The multicast service corresponds to one or more QoS flows, one or more SDFs of the multicast service may be mapped to the one or more QoS flows, and one or more SDFs may be mapped to one QoS flow.

For example, assuming that the SDF corresponding to the multicast service 1 includes SDF1, SDF2, SDF3, SDF1, SDF2 map to QoS flow 1, and SDF3 maps to QoS flow 2, the first session management network element may map QoS flow 1, QoS flow 2 to EPS bearer 1; alternatively, QoS flow 1 is mapped to EPS bearer 1, and QoS flow 2 is mapped to EPS bearer 2.

In another example, the first session management network element may obtain the second PCC rule from the policy control network element after the first terminal joins the multicast session or during the first session joins the multicast session, and determine the context of the EPS bearer corresponding to the multicast service according to the second PCC rule. Such as: when the first session management network element learns/discovers that the first terminal joins in the multicast session, the first session management network element sends a first event notification to the application server, the application server receives the first event notification and sends second description information to the first network element, the policy control network element formulates a second PCC rule according to the second description information and sends the second PCC rule to the first session management network element, and the first session management network element receives the second PCC rule and determines the context of the EPS bearer corresponding to the multicast service according to the second PCC rule.

Specifically, the determining, by the first session management network element according to the second PCC rule, the context of the EPS bearer corresponding to the multicast service may include: the first session management network element maps at least one SDF included in the second PCC rule to one or more EPS bearers, where the one or more SDFs may be mapped to one EPS bearer, and at the same time, configures an identifier of the EPS bearer for each EPS bearer, and configures a value of a QoS parameter of each EPS bearer to be equal to a sum of values of QoS parameters of all SDFs corresponding to the EPS bearer.

The second PCC rule may be determined by the policy control network element according to the second description information of the multicast service. The second description information of the multicast service may be used to specify a transmission requirement when the application server sends the data of the multicast service in a unicast manner, and the second description information of the multicast service may include: description information of one or more SDFs corresponding to the multicast service, and QoS requirements (such as bandwidth requirements, delay requirements, error rates and the like) of each SDF when the application server sends the multicast service in a unicast mode. The second description information of the multicast service may correspond to the first terminal, and the second description information of the multicast service may further include address information of the first terminal, such as an IP address of the first terminal.

For example, the application server may send the second description information to the policy control network element after determining that the first terminal joins the multicast session. In one implementation, the application server receives a first event notification, where the first event notification is used to notify the first terminal to join in the multicast session, and then the application server determines that the first terminal joins in the multicast session, and sends second description information corresponding to the multicast service to the first network element. The first session management network element may send a first event notification to the application server during the process that the first terminal joins the multicast session.

In this application, the first network element may be any one of a network open function network element, a network storage network element, a policy control network element, and a first session management network element, and the first network element may also be described as a core network element instead. The network open function network element may be NEF, the network storage network element may be UDM, UDR or URF, and the policy control network element may be PCF.

Further optionally, the first session management network element includes the context of the EPS bearer corresponding to the multicast service in the context information of the EPS bearer corresponding to the PDU session, and stores a correspondence between the identifier of the PDU session and the context information of the EPS bearer.

Optionally, after the first session management network element determines the context of the EPS bearer corresponding to the multicast service, the first session management network element sends an identifier of the EPS bearer corresponding to the multicast service and a QoS parameter corresponding to the EPS bearer to the source access network device, and/or the first session management network element sends the identifier of the EPS bearer corresponding to the multicast service to the first terminal, and optionally, the first session management network element may also send a packet filter of the EPS bearer to the terminal, where the packet filter is used to match a data packet of the multicast service to the EPS bearer.

S404: and the source access network equipment determines that the first terminal is switched and sends a switching request to the first mobility management network element.

The source access network device may be an access network device in the first network that provides a network service for the first terminal.

The Handover (HO) request may be used to request to handover the first terminal to the second network, where the handover request may include identification information of the first terminal and identification information of the target access network device, and may also include other information, such as: in the case that the first session management network element sends the context of the EPS bearer to the source access network device, the handover request may further include an identifier of the EPS bearer corresponding to the multicast service, or the identifier of the EPS bearer corresponding to the multicast service and the QoS parameter of the EPS bearer.

For example, the source access network device may carry an identifier of an EPS bearer corresponding to the multicast service, or the identifier of the EPS bearer corresponding to the multicast service and a QoS parameter of the EPS bearer in a container (container), where the container is transparent to the first mobility management network element, and the first mobility management network element cannot analyze information carried by the container, and only needs to transparently transmit the container to the target access network device through the second mobility management network element.

The identification information of the target access network device may be used to identify the target access network device, and the target access network device may be an access network device in the second network that provides a network service for the first terminal.

S405: the first mobility management network element receives the handover request and sends a first message to the first session management network element.

The first message may be used to request context information of an EPS bearer corresponding to a PDU session, and may also be used to instruct the first terminal to perform handover to a second network where the target access network device is located.

S406: and the first session management network element receives the first message and sends the context information of the EPS bearer to the first mobility management network element.

In one example, the first session management network element may send context information of an EPS bearer corresponding to the PDU session to the first mobility management network element. The context information of the EPS bearer includes a context of the EPS bearer corresponding to the multicast service. The context of the EPS bearer may include, as described above, the context of at least one EPS bearer corresponding to the multicast service, where the context of each EPS bearer includes an identifier of the EPS bearer and QoS parameters of the EPS bearer, and may also include downlink tunnel information of the first user plane network element corresponding to the EPS bearer.

Further optionally, after receiving the first message, the first session management network element may send a second event notification to the application server, where the second event notification may be used to notify the application server that the first terminal is about to switch to the second network, or to complete switching to the second network, or may be used to notify the application server that the first terminal is about to receive data of the multicast service through an EPS bearer, or may be used to notify the application server that the first terminal is about to receive data of the multicast service through a unicast session. Further, after receiving the second event notification, the application server prepares to start sending a data packet of the multicast service to the first user plane network element in a unicast manner, wherein a target address of the data packet of the multicast service is address information of the first terminal; or, the application server may still transmit the data packet of the multicast service in a multicast manner, where the data packet may include the data of the multicast service and the multicast address of the multicast service. Further, after receiving the second event notification, the application server may further send a third message to the first terminal, where the third message may be used to notify the first terminal to receive data of the multicast service through the EPS bearer or to notify the first terminal to receive data of the multicast service through the unicast session. Therefore, the application server can start to prepare for sending the data of the multicast service in a unicast mode in the process that the first terminal is switched from the first network to the second network, so that packet loss is avoided, and the continuity of data transmission after the first terminal is successfully switched to the second network is ensured.

It should be noted that the embodiment of the present application is not limited to the sending time of the second event notification, and optionally, the first session management network element may also send the second event notification to the application server after the first terminal completes the handover, for example, send the second event notification to the application server in the following S411, which is not limited.

The second event notification may be a notification message triggered after the second event occurs. For example, the application server may send a second subscription request to the first session management network element, requesting the first session management network element to notify the application server of a second event, where the second event may be that the first terminal switches from the first network to the second network or starts to switch the first terminal from the first network to the second network or that the first terminal successfully switches from the first network to the second network, so that the first session management network element sends the second event notification to the application server after knowing that the first terminal is switched or is about to start switching or has been successfully switched.

S407: and the first mobility management network element receives the context information of the EPS bearer and sends the context information of the EPS bearer to the second mobility management network element.

The second mobility management network element may be a mobility management network element, such as an MME, in the second network, for managing the target access network device. For example, the first mobility management network element may select the second mobility management network element from one or more mobility management network elements that manage the target access network device in the second network according to the identification information of the target access network device.

Further, the first mobility management network element may also send the identification information of the target access network device to the second mobility management network element.

S408: and the second mobility management network element receives the context information of the EPS bearer from the first mobility management network element and establishes a tunnel for each EPS bearer according to the context information of the EPS bearer.

The tunnel of the EPS bearer may include a tunnel between the first user plane network element and the target access network device. In the case that the serving gateway is deployed separately from the first user plane network element, the tunnel of the EPS bearer may include: a tunnel between the service gateway and the first user plane network element and a tunnel between the service gateway and the target access network device. In the case that the serving gateway and the first user plane network element are jointly configured, the tunnel carried by the EPS may include a tunnel between the first user plane network element and the target access network device.

In the following, a service gateway is taken as an SGW, and the SGW is separately deployed from the first user plane network element. The second mobility management network element may send a session establishment request to the SGW, where the session establishment request includes an identification of each EPS bearer and identification information of the first session management network element. After receiving the session establishment message, the SGW allocates downlink tunnel information of the SGW to each EPS bearer according to the identifier of the EPS bearer, and in S410, sends the downlink tunnel information of the SGW to the first session management network element according to the identifier information of the first session management network element, and the first session management network element sends the downlink tunnel information of the SGW to the first user plane network element to establish a tunnel between the first user plane network element and the SGW.

The downlink tunnel information of the SGW corresponds to the EPS bearer, one EPS bearer corresponds to one downlink tunnel information of the SGW, and the downlink tunnel information of the SGW is used for the SGW to receive data transmitted on the EPS bearer/data corresponding to the EPS bearer from the first user plane network element. The downlink tunnel information of the SGW may be an IP address and/or a Tunnel End Identifier (TEID) of the SGW.

It should be noted that the EPS bearer corresponding to the multicast service described in the present application is used for transmitting downlink data, and at this time, the SGW does not need to allocate uplink tunnel information because there is no uplink data or no uplink data to be transmitted on the EPS bearer. However, if the EPS bearer is also used for transmitting uplink data, the SGW may allocate uplink tunnel information of the SGW after receiving the session establishment request, where the uplink tunnel information of the SGW may be used for the SGW to receive data of the EPS bearer from the target access network device, and at this time, the context of the EPS bearer further includes downlink tunnel information of the first user plane network element.

In the present application, downlink data and uplink data are relative concepts, where the downlink data may refer to data sent from an application server to a terminal through an EPS bearer, and the uplink data may refer to data sent by the terminal to the application server through the EPS bearer.

It should be noted that, after S407 is executed, S409 is executed without executing S408 if the serving gateway and the first user plane network element are co-located and the tunnel of the EPS bearer includes the tunnel between the first user plane network element and the target access network device.

S409: and the second mobility management network element requests the target access network equipment to allocate radio resources for the EPS bearer, and acquires the information of the radio resources corresponding to the EPS bearer and the tunnel information of the target access network equipment from the target access network equipment.

The radio resource may be an air interface transmission resource used for transmitting data of the multicast service between the target access network and the first terminal. The information of the radio resource corresponding to the EPS bearer may be used to indicate the radio resource corresponding to the EPS bearer.

For example, the second mobility management network element may send the bearer identifier of the EPS bearer and the QoS information corresponding to the EPS bearer in the context of the EPS bearer acquired from the first mobility management network element to the target access network device, and send the uplink tunnel information of the SGW to the target access network device if there is uplink data. It should be noted that, if the handover request sent by the source access network device to the first mobility management network element in S404 carries a container, the container is also sent to the second mobility management network element by the first mobility management network element, and the second mobility management network element is sent to the target access network device. And the target access network equipment allocates radio resources for each EPS bearer according to the identifier of the EPS bearer in the context of the container and/or the EPS bearer and QoS information corresponding to the EPS bearer, and allocates downlink tunnel information of the target access network equipment for the EPS bearer. And the target access network equipment carries the information of the radio resources allocated for the EPS bearer in a container and sends the container and the downlink tunnel information of the target access network equipment to a second mobility management network element.

The downlink tunnel information of the target access network device corresponds to the EPS bearer, one EPS bearer corresponds to one downlink tunnel information of the target access network device, and the downlink tunnel information of the target access network device is used for the target access network device to receive data corresponding to the EPS bearer/data transmitted on the EPS bearer. The downlink tunnel information of the target access network device may be an IP address and/or a TEID of the target access network device.

The information of the radio resources may be used to indicate the radio resources allocated to the EPS bearer by the target access network device.

Further, after the above process is finished, the second mobility management network element may send the transparent container carrying the information of the radio resource allocated by the target access network device for the EPS bearer to the source access network device through the first mobility management network element, and the source access network device configures the first terminal according to the transparent container, for example, the transparent container is carried in a handover command (HO command) and sent to the first terminal. After receiving the information of the radio resources allocated to the EPS bearer by the target access network device, the first terminal accesses the target access network device according to the information of the radio resources allocated to the target access network device. And the target access network equipment sends a notification message to the second mobility management network element after sensing the access of the first terminal, and notifies the second mobility management network element that the first terminal is accessed from the target access network equipment.

S410: the second mobility management network element sends second indication information to the first session management network element.

The second indication information may be used to indicate that the handover of the first terminal is completed (handover complete) or successful (handover successful).

In one example, when the SGW is deployed independently, the second mobility management element may send second indication information to the first session management element via the SGW, such as: the second mobility management network element sends second indication information to the SGW, where the second indication information includes a handover indication for indicating that the first terminal is completed or successfully handed over, and after receiving the second indication information, the SGW sends a message for indicating that the first terminal is completed or successfully handed over, such as seventh indication information, to the first session management network element, where the seventh indication information also includes a handover indication for indicating that the first terminal is completed or successfully handed over. It should be noted that the seventh indication information and the second indication information may be different types of messages, and both of the seventh indication information and the second indication information may indicate that the first terminal is completed or the handover is successful, for example, both of the seventh indication information and the second indication information may carry a handover indication for indicating that the first terminal is completed.

The second indication information may include downlink tunnel information of the target access network device, so that the SGW obtains and stores the downlink tunnel information of the target access network device from the second indication information, establishes a tunnel between the SGW and the target access network device, and sends data transmitted on the EPS bearer to the target access network device according to the downlink tunnel information of the target access network device.

The seventh indication information may include downlink tunnel information allocated by the SGW for each EPS bearer, for example, downlink tunnel information of the SGW, and the first session management network element sends the received downlink tunnel information of the SGW to the first user plane network element, so that the first user plane network element receives and stores the downlink tunnel information of the SGW, establishes a tunnel between the SGW and the first user plane network element, and the first user plane network element sends data transmitted on the EPS bearer to the SGW according to the downlink tunnel information of the SGW.

In another example, when the user plane function of the SGW is co-located with the user plane network element and the control plane function of the SGW is co-located with the first session management network element, that is, the SGW is integrally deployed with other network elements, and the second mobility management network element may directly send the second indication information to the first session management network element when the SGW does not exist in the communication system. At this time, the second indication information may include downlink tunnel information of the target access network device, the first session management network element sends the received downlink tunnel information of the target access network device to the first user plane network element, so that the first user plane network element receives and stores the downlink tunnel information of the target access network device, and establishes a tunnel between the target access network device and the first user plane network element, and the first user plane network element sends data transmitted on the EPS bearer to the target access network device according to the downlink tunnel information of the target access network device.

S411: and the first session management network element receives the second indication information or the seventh indication information and sends a second message to the first user plane network element.

In one example, in a case that the first user plane network element is an anchor point corresponding to the multicast session, the second message may include a first mapping relationship between identification information of the multicast traffic flow and tunnel information of the EPS bearer (i.e., downlink tunnel information of the SGW or downlink tunnel information of the target access network device), where the identification information of the multicast traffic flow is used to identify the multicast traffic flow. The first mapping relationship may be used to instruct the first user plane network element to send data of the multicast service through an EPS bearer corresponding to the multicast service. Further, the first user plane network element receives and stores the first mapping relationship, so that a transmission tunnel for transmitting data of the multicast service from the application server to the first user plane network element and from the first user plane network element to the SGW/target access network device is successfully established. Subsequently, after the application server may send the data packet of the data of the multicast service to the first user plane network element, the first user plane network element sends the received data to the SGW/target access network device through the corresponding EPS bearer according to the first mapping relationship.

In another example, in a case that the first user plane network element is not an anchor point corresponding to the multicast session and the second user plane network element is an anchor point corresponding to the multicast session, the second message may include a second mapping relationship between the identifier of the QoS flow and tunnel information of the EPS bearer (i.e., downlink tunnel information of the SGW or downlink tunnel information of the target access network device), and the second mapping relationship may be used to map the QoS flow corresponding to the multicast service to the EPS bearer corresponding to the multicast service. Further, the first user plane network element receives and stores the second mapping relationship. Further, in another example, the second message is further used to obtain downlink tunnel information of the first user plane network element, and after the downlink tunnel information of the first user plane network element is obtained, the first session management network element sends the downlink tunnel information of the first user plane network element to the second user plane network element. The downlink tunnel information of the first user plane network element is used to establish a tunnel for transmitting data of the multicast service between the first user plane network element and the second user plane network element, and the downlink tunnel information of the first user plane network element may include an IP address of the first user plane network element and/or a TEID of the first user plane network element.

It should be noted that, in this embodiment of the application, when the SGW is deployed independently, the tunnel information carried by the EPS is downlink tunnel information of the SGW, and when the SGW is combined with the first user plane network element, the tunnel information carried by the EPS is downlink tunnel information of the target access network device.

Wherein, the sending, by the first session management network element, the downlink tunnel information of the first user plane network element to the second user plane network element may include:

when the first session management network element can manage the second user plane network element, the first session management network element directly sends the downlink tunnel information of the first user plane network element to the second user plane network element. And when the first session management network element cannot directly manage the second user plane network element, the first session management network element sends the downlink tunnel information of the first user plane network element to a session management network element for managing the second user plane network element. For example, as described above, if the session management network element managing the second user plane network element is the second session management network element, the first session management network element sends the downlink tunnel information of the first user plane network element to the second session management network element. And the second session management network element sends the tunnel information to the second user plane network element.

In addition, the session management network element managing the second user plane network element may send the identification information of the multicast service stream, the QFI corresponding to the identification information of the multicast service stream, and the downlink tunnel information of the first user plane network element corresponding to the identification information of the multicast service stream to the second user plane network element together, where the identification information of the multicast service stream and the QFI are used to map the service data stream of the multicast service to the QoS stream of the multicast service, and when the second user plane network element receives the data packet of the multicast service matching the identification information of the multicast service stream, the second user plane network element sends the QFI corresponding to the identification information and the data packet together to the first user plane network element through the tunnel corresponding to the tunnel information.

Further, the second user plane network element may store a corresponding relationship between identification information of the multicast service stream, QFI corresponding to the identification information of the multicast service stream, and downlink tunnel information of the first user plane network element, and the first user plane network element stores the second mapping relationship. And at this point, successfully establishing a transmission tunnel for transmitting data of the multicast service between the application server and the second user plane network element, between the second user plane network element and the first user plane network element, and between the first user plane network element and the SGW/target access network device. Subsequently, after the application server may send the data packet of the multicast service carrying the identification information of the multicast service stream to the second user plane network element, the second user plane network element sends the received data packet and the QFI together to the first user plane network element according to the correspondence between the identification information of the multicast service stream and the QFI and the downlink tunnel information of the first user plane network element, and after the first user plane network element receives the data packet including the data of the multicast service transmitted through the tunnel, the data packet is sent to the SGW/target access network device through one or more EPS bearers according to the second mapping relationship, the QFI corresponding to the data packet, and the identification of the EPS bearer.

Further, after receiving the second indication information or the seventh indication information, the first session management network element learns that the first terminal is completed or has been successfully switched, and may send a second event notification to the application server. The description of the second event notification may refer to the description in S406, which is not repeated.

Further, after receiving the second event notification, the application server prepares to start sending a data packet including the multicast service in a unicast manner, wherein a target address of the data packet of the multicast service is address information of the first terminal; or, the application server may still transmit the data packet of the multicast service in a multicast manner, where the data packet may include the data of the multicast service and the multicast address of the multicast service. Further, after receiving the second event notification, the application server may further send a third message to the first terminal, where the third message may be used to notify the first terminal to receive data of the multicast service through the EPS bearer or to notify the first terminal to receive data of the multicast service through the unicast session. Therefore, the application server can start to prepare for sending the data of the multicast service after the first terminal is switched, so that packet loss is avoided, and the continuity of data transmission after the first terminal is successfully switched to the second network is ensured.

And the first terminal is successfully switched into the second network, is connected with the target access network equipment in the second network, and receives the data of the multicast service through the EPS bearer.

In this application, the target access network device may be an access network device supporting MBMS bearer or an access network device not supporting MBMS bearer. If the target access network device supports the transmission of the data of the multicast service through the MBMS bearer, or there is another access network device at the location of the first terminal that supports the transmission of the data of the multicast service in the MBMS bearer manner, at this time, the first terminal may switch the reception of the multicast service of the first terminal from the EPS bearer (i.e., unicast bearer) to the MBMS bearer. The MBMS area may refer to an area supporting reception of data of the multicast service through an MBMS bearer. The process of switching the multicast service of the first terminal from receiving via the EPS bearer to receiving via the MBMS bearer may refer to the following S412 to S414:

s412: the first terminal detects that the first terminal enters the MBMS area of the multicast service.

For example, the first terminal may obtain information of an MBMS corresponding to the multicast service in advance, such as a TMGI of the multicast service, and the first terminal may monitor a radio channel according to the information of the MBMS corresponding to the multicast service to determine whether the first terminal enters an MBMS area of the multicast service, and if the information of the MBMS (e.g., the TMGI of the multicast service) that is sent by an MBMS bearer is monitored, determine to enter the MBMS area of the multicast service.

The information of the MBMS may include a TMGI of the multicast service, and may further include radio configuration information corresponding to MBMS bearer and other information. As shown in fig. 1b, the transmission path of the MBMS bearer is: the application server is connected to the BMSC, the BMSC is connected to the MBSC-GW, the MBSC-GW is connected to the target access network equipment, and the target access network equipment is connected to the first terminal.

S413: the first terminal sends a first report to the application server.

The first report may be used to indicate that the first terminal enters an MBMS area corresponding to the multicast service in the second network, and may receive data of the multicast service through an MBMS bearer in the second network or support receiving data of the multicast service through the MBMS bearer in the second network. The first report may include identification information of the first terminal.

Illustratively, the first terminal may send the first report to the application server over an EPS bearer of the first terminal.

S414: and the application server receives the first report and sends fifth indication information to the first network element.

Wherein the fifth indication information may be used to indicate that the first terminal stops receiving data of the multicast service through the EPS bearer in the second network. The present application is not limited to the content of the indication of the fifth indication information, and alternatively, the content of the indication of the fifth indication information may be any of the following: the data indicating that the multicast service is stopped being sent to the first terminal through the EPS bearer, the data indicating that the multicast service is no longer sent through the EPS bearer, the data indicating that the first terminal is receiving the multicast service through the MBMS bearer, the data indicating that the first network element can receive the multicast service through the MBMS bearer, and the data indicating that the first terminal is no longer required to receive the multicast service through the EPS bearer. The meaning of these indication contents referred by the fifth indication information is the same, and these indication contents may indirectly or directly indicate that the data of the multicast service is no longer sent to the first terminal through the EPS bearer, but the data of the multicast service is sent to the first terminal through the MBMS bearer, and these indication contents may be used alternatively, for example, the data of the fifth indication information for indicating that the reception of the multicast service through the EPS bearer in the second network is stopped may be described as the data for indicating that the transmission of the multicast service to the first terminal through the EPS bearer is stopped instead.

In addition, if the application server receives the first event notification and sends the second description information to the first network element, the fifth indication information may also be used to indicate to delete the second description information corresponding to the multicast service, that is, in this case, the fifth indication information is the indication information for deleting the second description information.

To this end, the first terminal receives data of the multicast service through the MBMS bearer in the second network.

Further, if the fifth indication information is used to indicate to delete the second description information corresponding to the multicast service, the first network element may further trigger the policy control network element to delete the second description information and delete the second PCC rule generated according to the second description information, in a process of deleting the second PCC rule, the first network element sends the third indication information to the first session management network element, at this time, for the first session management network element, the third indication information may be used to indicate to delete the second PCC rule, the first session management network element deletes/releases the radio resource allocated according to the second PCC rule and used to transmit the EPS bearer corresponding to the multicast service, and the first session management network element releases the radio resource used to transmit the EPS bearer corresponding to the multicast service after receiving the third indication information. Deleting the second PCC rule means that the transmission resource corresponding to the EPS bearer determined according to the second PCC rule is also deleted/released, so that the data of the multicast service can not be sent through the EPS bearer any more.

Further, if the fifth indication information is only used for indicating to stop sending the data of the multicast service to the first terminal through the EPS bearer (i.e., not used for indicating to delete the second description information); or, the first terminal is used for indicating that the first terminal is receiving data of the multicast service through the MBMS bearer; or, the first network element is configured to send, to the first session management network element, third indication information for indicating that the first terminal may receive the data of the multiple services through the MBMS bearer, where the third indication information may be used to indicate that the sending of the data of the multicast service to the first terminal through the EPS bearer is stopped; or, the first terminal is used for indicating that the first terminal is receiving data of the multicast service through the MBMS bearer; or, the first terminal may be configured to receive the data of the plurality of services through the MBMS bearer. Further, the first session management network element determines to stop/no longer send the data of the multicast service to the first terminal through the EPS bearer according to the third indication information, and the first session management network element may deactivate the radio resource of the EPS bearer used for transmitting the data of the multicast service.

Further, after receiving the third indication information, the first session management network element sends the first configuration information to the first user plane network element, where the first configuration information may be used to notify the first user plane network element to stop/no longer send the data of the multicast service to the first terminal through the EPS bearer. And the first user plane network element receives the first configuration information, and stops or no longer sends the data of the multicast service to a downlink node corresponding to the EPS bearer, such as SGW/target access network equipment, through the EPS bearer. Further, the first configuration information may also be used to indicate a first mapping relationship or a second mapping relationship that is received and stored by the first user plane network element before the first user plane network element deletes the first user plane network element.

Further, the first terminal has mobility, and after moving to the MBMS area, the first terminal may move out of the MBMS area, so that data of the multicast service cannot be received through the MBMS bearer. For example, as shown in fig. 1b, the terminal 1 moves out of the MBMS area in the second network and cannot receive data of the multicast service through the MBMS bearer. When the first terminal moves out of the MBMS area, the multicast service data may be switched to be transmitted through EPS bearer transmission again, which specifically includes:

the first terminal detects that the first terminal moves out of the MBMS area, and sends a second report to the application server, wherein the second report can be used for indicating that the first terminal moves out of the MBMS area of the multicast service, namely the first terminal does not support receiving data of the multicast service through the MBMS area in the second network any more;

the application server receives the second report of the first terminal, and sends sixth indication information to the first network element, where the sixth indication information may be used to indicate that a corresponding resource is created for the first terminal to receive the multicast service through the EPS bearer or to indicate that the first terminal may/supports receiving data of the multicast service through the EPS bearer.

Further, in the case that the fifth indication information is used to indicate that the second description information is deleted, the sixth indication information may carry the second description information, that is, the application server may send the second description information to the first network element again, so as to request to send and allocate radio resources of a corresponding EPS bearer through a unicast bearer for the multicast service. For example, after receiving the sixth indication information, the first network element triggers the policy control network element to formulate a second PCC rule according to the second description information, and sends fourth indication information to the first session management network element, where the fourth indication information may be used to indicate that data of the multicast service is sent to the first terminal through an EPS bearer or indicate that a corresponding resource is created for the first terminal to receive the multicast service through the EPS bearer, and at this time, the fourth indication information may include/be the second PCC rule. Further, the first session management network element determines, according to the second PCC rule, an EPS bearer required for sending the multicast service.

Alternatively, the sixth indication information may not carry the second description information, the first network element sends, after receiving the sixth indication information, fourth indication information to the first session management network element, where the fourth indication information may be used to indicate that data of the multicast service is sent to the first terminal through an EPS bearer or indicate that a corresponding resource is created for the first terminal to receive the multicast service through the EPS bearer, and the fourth indication information does not include the second PCC rule, at this time, the first session management network element may determine, according to the locally stored first PCC rule, an EPS bearer required by the multicast service flow, and the first session management network element includes, in the second configuration information, a correspondence between identification information of the multicast service flow and tunnel information of the EPS bearer.

Further, after receiving the fourth indication information, the first session management network element sends second configuration information to the first user plane network element, where the second configuration information is used to notify the first user plane network element to send data of the multicast service through the EPS bearer. And after receiving the second configuration information, the first user plane network element continues/sends the data of the multicast service through the EPS bearer again. Further, the second configuration information may also be configured to send the first mapping relationship or the second mapping relationship to the first user plane network element, so that the first user plane network element may send the received data of the multicast service through the EPS bearer corresponding to the multicast service according to the first mapping relationship or the second mapping relationship.

Further, the first session management network element may further notify the SGW and the access network device accessed by the first terminal in the second network to allocate resources for the EPS bearer of the multicast service. Specifically, the method can be referred to in the prior art, and is not described in detail here.

In the process shown in the foregoing steps S412 to S414, after the first terminal moves to the MBMS area of the multicast service, the first terminal sends a first report to the application server, and triggers the application server to notify the first session management network element through the first network element to stop/stop sending the data of the multicast service through the EPS bearer, delete the radio resource of the EPS bearer, and switch the data of the multicast service sent through the EPS bearer to the data of the multicast service sent through the MBMS bearer, that is, trigger the first session management network element to switch between the EPS bearer and the MBMS bearer from the application server side. Further, when the first terminal moves out of the MBMS area, the application server is triggered to notify the first session management network element to stop/stop sending the data of the multicast service through the MBMS bearer, and to switch to sending the data of the multicast service through the EPS bearer.

Alternatively, the present application further provides a method, when the first terminal moves to the MBMS area, the first terminal directly sends the indication information to the first session management network element, indicates to stop/no longer send the data of the multicast service through the EPS bearer, switches to the MBMS bearer to send the data of the multicast service, and reduces a delay from the EPS bearer to the MBMS bearer. Specifically, the process may include:

the first terminal detects that the first terminal enters an MBMS area of the multicast service, or the first terminal determines that the data of the multicast service is sent through EPS bearing (namely EPS bearing connected with PDN);

and the first terminal sends the eighth indication information to the first session management network element. Further, the first session management network element receives the eighth indication information, and performs a corresponding action according to the eighth indication information, such as deactivating a radio resource of an EPS bearer used for transmitting the data of the multicast service.

The eighth indication information may be used to indicate to delete the EPS bearer corresponding to the multicast service, or the eighth indication information is used to indicate that the first terminal is receiving data of the multicast service through the MBMS. The eighth indication information may be an EPS bearer modification or deletion request message, or the eighth indication information is carried in the EPS bearer modification or EPS bearer deletion request message. The eighth indication information may carry identification information of the multicast service, for example, the TMGI of the multicast service or the multicast address of the multicast service, or an EPS Bearer Identifier (EBI) of an EPS bearer corresponding to the multicast service.

In an implementation, the eighth indication information is an EPS bearer modification or EPS bearer deletion request message, and in this implementation, the identification information of the multicast service is included in the flow description information (such as a packet filter corresponding to the multicast service) that needs to be deleted, or is included in an EPS bearer identification field of the EPS bearer modification or EPS bearer deletion request message.

Further, when the first terminal moves out of the MBMS area corresponding to the multicast service again, the first terminal cannot receive the data of the multicast service through the MBMS bearer. At this time, the first terminal may send the ninth indication information to the first session management network element, indicate to stop/no longer send the data of the multicast service through the MBMS bearer, switch to the EPS bearer to send the data of the multicast service, and reduce a delay of switching from the MBMS bearer to the EPS bearer.

The ninth indication information is used to indicate that the first terminal moves out of the MBMS area of the multicast service or that the first terminal needs to receive the data of the multicast service through an EPS bearer (that is, the first terminal cannot receive the data of the multicast service through the MBMS bearer), or to request to create an EPS bearer for the multicast service. The ninth indication information may include an identifier of the multicast service, for example, the ninth indication information may carry a TMGI of the multicast service or a multicast address of the multicast service, or an EPS Bearer Identifier (EBI) of an EPS bearer corresponding to the multicast service.

In one implementation, the ninth indication information may be an EPS bearer allocation or modification request message or carried in the EPS bearer allocation or modification request message. The identification of the multicast traffic may be included in the flow description information, e.g. the flow description information includes the multicast address and optionally the source and/or destination port number of the multicast traffic.

Based on the method described in fig. 4, the first session management network element may determine context information of an EPS bearer corresponding to the multicast service when the first terminal joins the multicast session, and send the context information of the EPS bearer corresponding to the multicast service to the first mobility management network element when the first terminal is switched, so that the first mobility management network element triggers the second mobility management network element to establish a tunnel of the EPS bearer corresponding to the multicast service, so that when the first terminal is switched to the second network, the application server sends data of the multicast service to the first terminal through the EPS bearer, thereby ensuring continuity of multicast service transmission. Meanwhile, when the first terminal moves out of the area corresponding to the EPS bearer to the MBMS area, the data of the multicast service is stopped to be sent through the EPS bearer, and the data of the multicast service is switched to be sent through the MBMS bearer, so that the data transmission performance is improved.

Referring to fig. 2, a first network is a 5G network, a second network is a 4G network, a first terminal is a terminal 1, a first session management network element is PGW + C + SMF, a first user plane network element is PGW-U + UPF, the first user plane network element is an anchor point of a multicast session, the PGW + C + SMF is a session management network element for managing the multicast service, the first user plane network element has a function of transmitting data of the multicast service, the first mobility management network element is AMF, the second mobility management network element is MME, the source access network device is gNB, the target access network device is eNB, the SGW is deployed independently, the application server is AS, the first network element is NEF/PCF, the EPS bearer is used for transmitting downlink data corresponding to downlink data/EPS bearer, and the AS an example of transmitting the multicast service in a multicast manner, which details the method shown in fig. 4.

Fig. 5 is a flowchart of a service switching method provided in an embodiment of the present application, and as shown in fig. 5, the method may include:

s501: terminal 1 establishes a PDU session for terminal 1.

Wherein, the transmission path of the PDU session of the terminal 1 is: AS < - > PGW-U + UPF < - > gNB < - > terminal 1. The specific execution process of S501 can be described with reference to S401, and is not described in detail.

S502: the terminal 1 requests to join the multicast session to the PGW-C + SMF, and the PGW-C + SMF establishes the multicast session (optional) and joins the multicast session corresponding to the multicast service.

Wherein, the transmission path of the multicast session is: AS < - > PGW-U + UPF < - > gNB < - > terminal, which includes terminal 1. The specific execution process of S502 can be described with reference to S402, and is not described in detail.

S503: and the PGW-C + SMF determines the context of the EPS bearer corresponding to the multicast service when the terminal 1 joins the multicast session.

The PGW-C + SMF may determine, according to the first PCC rule, a context of an EPS bearer corresponding to the multicast service. The specific implementation process of S503 and the related description of the EPS bearer may refer to that in S403, which is not described in detail.

S504: and the gNB determines that the terminal 1 is switched, switches from the 5G network to the 4G network, and sends a switching request to the AMF.

The description of the handover request and the specific execution process of S504 may refer to S404, which is not repeated herein.

S505: and the AMF receives the switching request, learns that the terminal 1 is switched according to the switching request, and sends a first message to the PGW-C + SMF to request the context information of the EPS bearer corresponding to the multicast service.

The related description of the first message and the specific execution process of S505 may refer to S405, which is not repeated herein.

S506: and the PGW-C + SMF receives the first message and sends the context information of the EPS bearer to the AMF.

S506 can be referred to as S406, and is not repeated herein.

S507: and the AMF receives the context information of the EPS bearer and sends the context information of the EPS bearer to the MME.

S507 can be described with reference to S407, and is not repeated herein.

S508: and the MME receives the context information of the EPS bearer, sends a session establishment request to the SGW according to the context information of the EPS bearer and requests the SGW to establish a tunnel for each EPS bearer.

The relevant description of the session establishment request and the specific execution process of S508 are described with reference to S408, and are not repeated herein.

S509: and the SGW allocates the downlink tunnel information of the SGW for the EPS bearer and sends a session establishment response to the MME, wherein the session establishment response carries the downlink tunnel information of the SGW.

S510: and the MME requests the eNB to allocate radio resources and the downlink tunnel information of the eNB for the EPS bearing.

S510 may refer to S409, which is not described herein.

S511: and the eNB receives the request of the MME, allocates the radio resource for the EPS bearer and allocates the downlink tunnel information of the eNB, and carries the radio resource information of the EPS bearer in a transparent container and sends the information and the downlink tunnel information of the eNB to the MME.

S512: the MME receives the transparent container and downlink tunnel information of the eNB from the eNB and transmits the transparent container to the AMF.

S513: the AMF receives the transparent container from the MME and sends the transparent container to the gNB.

S514: and the gNB receives the transparent container and sends a switching command to the terminal 1, wherein the switching command carries the information of the radio resource carried by the EPS.

S515: the terminal 1 receives the handover command from the gNB, connects to the eNB according to the information of the radio resource carried by the EPS, and disconnects from the gNB.

S516: the eNB sends a notification message to the MME notifying the MME that the handover of the terminal 1 is completed.

S517: and the MME receives the notification of the eNB and sends second indication information to the SGW, wherein the second indication information carries a switching indication, and the second indication information carries the downlink tunnel information of the eNB received by the MME in the S512.

S518: and the SGW receives the second indication information, stores the downlink tunnel information of the eNB, and sends seventh indication information to the PGW-C + SMF according to the identification information of the PGW-C + SMF carried in the session establishment request, wherein the seventh indication information also carries a switching indication, and the seventh indication information carries the downlink tunnel information of the SGW.

S519: and the PGW-C + SMF receives the seventh indication information, learns that the terminal 1 is switched, and sends a second message carrying the first mapping relation to the PGW-U + UPF. Accordingly, the PGW-U + UPF receives and stores the first mapping relationship.

In the embodiment of the application, the AS sends a data packet of the multicast service to the PGW-U + UPF, where the data packet includes data of the multicast service and a multicast address of the multicast service. In this case, a packet of the multicast service received by the PGW-U + UPF may be sent to multiple terminals, for example, the terminal 2 also establishes an EPS bearer to the PGW-U + UPF and receives the packet of the multicast service through the EPS bearer. Therefore, the second message may also be used to instruct the PGW-U + UPF to copy the data packet of the multicast service after receiving the data packet and send the data packet through the EPS bearer of the terminal 1 (i.e., using the downlink tunnel information of the SGW). If the terminal 2 exists at the same time, the PGW-U + UPF copies the data packet after receiving the data packet and sends the data packet through the EPS bearer of the terminal 2.

In this embodiment, the description about the first mapping relationship and the specific execution process of S519 are described with reference to S411, where the identification information of the multicast service flow in the first mapping relationship is used to identify description information of one or more SDFs of the multicast service when the AS transmits in a multicast manner.

To this end, the transmission path of the EPS bearer: and completing the establishment of the AS < - > PGW-U + UPF < - > SGW < - > eNB < - > terminal 1.

S520: and the PGW-C + SMF sends a second event notification to the AS.

The second event notification may be used to notify the terminal 1 that handover to the 4G network is about to be performed or handover to the 4G network is completed. Specifically, the description of the second event notification can be described with reference to fig. 4, and is not repeated.

S521: and the AS receives the second event notification and sends a third message to the terminal 1, wherein the third message is used for notifying the terminal 1 to receive the data of the multicast service through the EPS bearer.

Further, the AS sends a data packet of the multicast service to the PGW-U + UPF, and the PGW-U + UPF receives the data packet of the multicast service and sends the data packet of the multicast service to the terminal 1 through the EPS bearer.

Alternatively, the second event notification described in S520 may also be sent to the AS after the PGW-C + SMF receives the first message in S506, that is, S520 and S521 may be executed in S506, or sent at any time between S506 and S520, without limitation.

Subsequently, if the terminal 1 moves from the unicast zone/EPS bearer zone to the MBMS zone of the multicast service, S522 to S526 are performed.

S522: the terminal 1 detects that it enters the MBMS area of the multicast service.

The specific execution process of S522 can be referred to as that described in S412, and is not described in detail.

S523: the terminal 1 sends a first report to the AS.

The related description of the first report and the specific execution process of S523 can be executed with reference to S413, and are not repeated.

S524: the AS receives the first report and sends fifth indication information to the NEF/PCF.

The description of the fifth indication information may refer to S414, where the fifth indication information may be used to instruct the terminal 1 to stop receiving the data of the multicast service through the EPS bearer in the second network, or to notify that the data of the multicast service is stopped being sent through the EPS bearer, or to instruct the data of the multicast service to be no longer sent through the EPS bearer, or to instruct the first terminal to receive the data of the multicast service through the MBMS bearer.

S525: and the NEF/PCF receives the fifth indication information and sends the third indication information to the PGW-C + SMF.

S526: the PGW-C + SMF receives the third indication information, deletes/releases the radio resource used for transmitting the EPS bearer corresponding to the multicast service, and sends the first configuration information to the first user plane network element, where the first configuration information may be used to notify the first user plane network element to stop/no longer send the data of the multicast service through the EPS bearer. And the first user plane network element receives the first configuration information, and stops/does not send the data of the multicast service to the SGW/target access network equipment through the EPS bearer. In the embodiment shown in fig. 5, the first configuration information may also be used to instruct the PGW-U + UPF to delete the first mapping relationship.

Further, if the terminal 1 moves from the MBMS area to the unicast area again, which results in that the data of the multicast service cannot be received through the MBMS bearer, the method further includes: the terminal 1 detects that the terminal 1 moves out of the MBMS area of the multicast service, sends a second report for indicating that the terminal 1 moves out of the MBMS area of the multicast service to the AS, receives the second report of the terminal 1 and sends sixth indication information for indicating that the terminal 1 receives the multicast service through EPS bearing to the NEF/PCF. And the NEF/PCF receives the sixth indication information, sends fourth indication information to the PGW-C + SMF, the PGW-C + SMF receives the fourth indication information, and sends second configuration information to the PGW-U + UPF, wherein the second configuration information is used for informing the PGW-U + UPF to send the data of the multicast service through EPS bearer. And after receiving the second configuration information, the PGW-U + UPF continues/sends the data of the multicast service through the EPS bearer again. In the embodiment shown in fig. 5, the second configuration information may also be used to send the first mapping relationship to the PGW-U + UPF, for example, the second configuration information may carry the first mapping relationship, so that the PGW-U + UPF may send the received data packet of the multicast service through the EPS bearer corresponding to the multicast service according to the first mapping relationship.

The description of the second report, the third indication information, the fourth indication information, the fifth indication information, the sixth indication information, and the second configuration information may refer to fig. 4, and is not repeated.

Based on the method shown in fig. 5, the PGW-C + SMF may determine the context information of the EPS bearer in the multicast session joined by the terminal 1, and send the context information of the EPS bearer to the AMF when the terminal 1 is switched, so that the AMF triggers the MME to establish a tunnel of the EPS bearer, and when the terminal 1 is switched to the second network, the AS sends the data of the multicast service to the terminal 1 through the EPS bearer, thereby ensuring the continuity of multicast service transmission. Meanwhile, when the terminal 1 moves out of the area corresponding to the EPS bearer to the MBMS area, the transmission of the data of the multicast service through the EPS bearer is stopped, and the transmission of the data of the multicast service through the MBMS bearer is switched, thereby improving the data transmission performance.

Referring to fig. 2, the method shown in fig. 4 is described in detail below by taking an example that a first network is a 5G network, a second network is a 4G network, a terminal 1 is a terminal 1, a first session management network element is PGW + C + SMF, a first user plane network element is PGW-U + UPF, and UPF1 are anchors of a multicast session (i.e., a second user plane network element), SMF1 is a session management network element (i.e., a second session management network element) for managing a multicast service, a first mobility management network element is AMF, a second mobility management network element is MME, a source access network device is gNB, a target access network device is eNB, an SGW is deployed independently, an application server is AS, a first network element is NEF/PCF, an EPS carries downlink data corresponding to downlink data/EPS bearer, and the AS sends data of the multicast service in a multicast manner.

Fig. 6 is a flowchart of a service switching method according to an embodiment of the present application, where the difference between fig. 6 and fig. 5 is: in fig. 5, PGW-U + UPF may be directly connected to an AS, where PGW-U + UPF is a downstream entry of data of a multicast service, UPF1 is directly connected to the AS in fig. 6, UPF1 is a downstream entry of data of the multicast service, a session management network element corresponding to the multicast session in fig. 6 is SMF1, and UPF1 is managed by SMF 1. As shown in fig. 6, the service switching method may include:

s601: terminal 1 establishes a PDU session for terminal 1.

Wherein, the transmission path of the PDU session of the terminal 1 is: AS < - > PGW-U + UPF < - > gNB < - > terminal 1. The specific execution process of S601 can be described with reference to S401, and is not described in detail.

S602: the terminal 1 requests to join the multicast session to the PGW-C + SMF, and the PGW-C + SMF triggers the SMF1 to establish the multicast session corresponding to the multicast service and join the multicast session corresponding to the multicast service.

Wherein, the transmission path of the multicast session is: AS < - > UPF1< - > gNB < - > terminal, including terminal 1. The specific execution process of S602 may refer to that described in S402, and is not described in detail.

S603: when the terminal 1 joins in the multicast session, the PGW-C + SMF acquires QoS flow information corresponding to the multicast service from the SMF1, and determines a context of an EPS bearer corresponding to the multicast service according to the QoS flow information corresponding to the multicast service.

The specific execution process of S603 and the related description of the EPS bearer may refer to S403, which is not described in detail.

S604: and the gNB determines that the terminal 1 is switched, switches from the 5G network to the 4G network, and sends a switching request to the AMF.

The description of the handover request and the specific execution process of S604 may refer to S404, which is not repeated herein.

S605: and the AMF receives the switching request, learns that the terminal 1 is switched according to the switching request, and sends a first message to the PGW-C + SMF to request the context information of the EPS bearer corresponding to the multicast service.

The related description of the first message and the specific execution process of S605 may refer to S405, which is not described in detail.

S606: and the PGW-C + SMF receives the first message and sends the context information of the EPS bearer to the AMF.

S606 can be described with reference to S406, and is not described in detail.

S607: and the AMF receives the context information of the EPS bearer and sends the context information of the EPS bearer to the MME.

S607 can be referred to as S407, and is not repeated herein.

S608: and the MME receives the context information of the EPS bearer, sends a session establishment request to the SGW according to the context information of the EPS bearer and requests the SGW to establish a tunnel for each EPS bearer.

The relevant description of the session establishment request and the specific execution process of S608 refer to S408, which is not described in detail.

S609: and the SGW allocates the downlink tunnel information of the SGW for the EPS bearer and sends a session establishment response to the MME, wherein the session establishment response carries the downlink tunnel information of the SGW.

S610: and the MME requests the eNB to allocate radio resources and downlink tunnel information for the EPS bearer.

S610 may refer to S409, which is not described herein.

S611: and the eNB receives the request of the MME, allocates the radio resource for the EPS bearer and allocates the downlink tunnel information of the eNB, and carries the radio resource information of the EPS bearer in a transparent container and sends the information and the downlink tunnel information of the eNB to the MME.

S612: the MME receives the transparent container and downlink tunnel information of the eNB from the eNB and transmits the transparent container to the AMF.

S613: the AMF receives the transparent container from the MME and sends the transparent container to the gNB.

S614: and the gNB receives the transparent container and sends a switching command to the terminal 1, wherein the switching command carries the information of the radio resource carried by the EPS.

S615: the terminal 1 receives the handover command from the gNB, connects to the eNB according to the information of the radio resource carried by the EPS, and disconnects from the gNB.

S616: the eNB sends a notification message to the MME notifying the terminal 1 of the completion of the handover.

S617: and the MME receives the notification of the eNB and sends second indication information to the SGW, wherein the second indication information indicates that the terminal 1 is switched to be completed, and the second indication information carries the downlink tunnel information of the eNB received by the MME.

S618: and the SGW receives the second indication information, stores the downlink tunnel information of the eNB, and sends seventh indication information to the PGW-C + SMF according to the identification information of the PGW-C + SMF carried in the session establishment request, wherein the seventh indication information also indicates that the terminal 1 is switched to be completed, and the seventh indication information carries the downlink tunnel information of the SGW.

S619: and the PGW-C + SMF receives the seventh indication information, learns that the terminal 1 is switched, and sends a second message carrying a second mapping relation to the PGW-U + UPF. Accordingly, the PGW-U + UPF receives and saves the second mapping relationship.

The second message is further used for acquiring the downlink tunnel information of the PGW-U + UPF, so that the PGW-C + SMF sends the acquired downlink tunnel information of the PGW-U + UPF to the UPF1, and a transmission tunnel between the UPF1 and the PGW-U + UPF is established.

The related description of the second mapping relationship and the specific execution process of S619 are described with reference to S411, and are not repeated.

S620: and the PGW-C + SMF sends the downlink tunnel information of the PGW-U + UPF to the SMF 1.

S621: the SMF1 receives the downlink tunnel information of the PGW-U + UPF and sends the downlink tunnel information of the PGW-U + UPF to the UPF 1. Correspondingly, the UPF1 receives and stores the downlink tunnel information of the PGW-U + UPF.

And therefore, establishing a transmission path of the EPS bearer: AS < - > UPF1< - > PGW-U + UPF < - > SGW < - > eNB < - > terminal 1.

S622: and the PGW-C + SMF sends a second event notification to the AS.

S623: and the AS receives the second event notification and sends a third message to the terminal 1, wherein the third message is used for notifying the terminal 1 to receive the data of the multicast service through the EPS bearer.

Further, the AS sends the data of the multicast service to the UPF1, the UPF1 receives the data of the multicast service, sends the data of the multicast service to the PGW-U + UPF according to the downlink tunnel information of the PGW-U + UPF, the PGW-U + UPF receives the data of the multicast service, and sends the data of the multicast service to the terminal 1 through the EPS bearer according to the second mapping relationship.

Alternatively, the second event notification described in S620 may also be sent to the AS after the PGW-C + SMF receives the first message in S606, that is, S620 and S621 may be executed in S606, or executed at any time between steps S606 to S621, without limitation.

Subsequently, if the terminal 1 moves from the unicast zone/EPS bearer zone to the MBMS zone of the multicast service, S624 to S628 are performed.

S624: the terminal 1 detects that it enters the MBMS area of the multicast service.

The specific execution process of S624 can be referred to as S412, and is not described in detail.

S625: the terminal 1 sends a first report to the AS.

The related description of the first report and the specific execution process of S625 may be executed with reference to S413, and are not repeated herein.

S626: the AS receives the first report and sends fifth indication information to the NEF/PCF.

The description of the fifth indication information may refer to that in S414, and the fifth indication information may be used to instruct the terminal 1 to stop receiving the data of the multicast service through the EPS bearer in the second network, or to notify the first network element to stop sending the data of the multicast service through the EPS bearer, or to indicate that the data of the multicast service is no longer sent through the EPS bearer. In the embodiment shown in fig. 6, the first configuration information may also be used to instruct the PGW-U + UPF to delete the second mapping relationship.

S627: and the NEF/PCF receives the fifth indication information and sends the third indication information to the PGW-C + SMF.

S628: the PGW-C + SMF receives the third indication information, deletes/releases the radio resource used for transmitting the EPS bearer corresponding to the multicast service, and sends the first configuration information to the first user plane network element, where the first configuration information may be used to notify the first user plane network element to stop/no longer send the data of the multicast service through the EPS bearer. And the first user plane network element receives the first configuration information, and stops/does not send the data of the multicast service to the SGW/target access network equipment through the EPS bearer.

Further, if the terminal 1 moves from the MBMS area to the unicast area again, which results in that the data of the multicast service cannot be received through the MBMS bearer, the method further includes: the terminal 1 detects that the terminal 1 moves out of the MBMS area of the multicast service, sends a second report for indicating that the terminal 1 moves out of the MBMS area of the multicast service to the AS, receives the second report of the terminal 1 and sends sixth indication information for indicating that the terminal 1 receives the multicast service through EPS bearing to the NEF/PCF. And the NEF/PCF receives the sixth indication information, sends fourth indication information to the PGW-C + SMF, the PGW-C + SMF receives the fourth indication information, and sends second configuration information to the PGW-U + UPF, wherein the second configuration information is used for informing the PGW-U + UPF to send the data of the multicast service through EPS bearer. And after receiving the second configuration information, the PGW-U + UPF continues/sends the data of the multicast service through the EPS bearer again. In the embodiment shown in fig. 6, the second configuration information may also be used to send the second mapping relationship to the PGW-U + UPF, for example, the second configuration information may carry the second mapping relationship, so that the PGW-U + UPF may send the received data packet of the multicast service through the EPS bearer corresponding to the multicast service according to the second mapping relationship.

Based on the method shown in fig. 6, the PGW-C + SMF may obtain QoS flow information corresponding to the multicast service from the SMF1 when the terminal 1 joins in the multicast session, determine context information of an EPS bearer corresponding to the multicast service according to the QoS flow information corresponding to the multicast service, and send the context information of the EPS bearer corresponding to the multicast service to the AMF when the terminal 1 is switched, so that the AMF triggers the MME to establish a tunnel of the EPS bearer, so that when the terminal 1 is switched to the second network, the AS sends data of the multicast service to the PGW-U + SMF through the UPF1, and the PGW-U + SMF sends the data of the multicast service to the terminal 1 through the EPS bearer, thereby ensuring continuity of multicast service transmission. Meanwhile, when the terminal 1 moves out of the area corresponding to the EPS bearer to the MBMS area, the transmission of the data of the multicast service through the EPS bearer is stopped, and the transmission of the data of the multicast service through the MBMS bearer is switched, thereby improving the data transmission performance.

With reference to fig. 2, the method shown in fig. 4 is described in detail by taking an example that a first network is a 5G network, a second network is a 4G network, a terminal 1 is a terminal 1, a first session management network element is PGW + C + SMF, a first user plane network element is PGW-U + UPF, the first user plane network element is an anchor point of a multicast session, PGW + C + SMF is a session management network element for managing a multicast service, the first user plane network element has a function of transmitting data of the multicast service, the first mobility management network element is AMF, the second mobility management network element is MME, a source access network device is gNB, a target access network device is eNB, the SGW is deployed independently, an application server is AS, the first network element is NEF/PCF, the EPS carries downlink data corresponding to downlink data for transmitting the downlink data/EPS, and the AS sends data of the multicast service in a unicast manner.

Fig. 7 is a flowchart of a service switching method according to an embodiment of the present application, where fig. 7 is different from fig. 5 and fig. 6 in that: in fig. 7, the PGW + C + SMF determines the context of the EPS bearer according to the second PCC rule corresponding to the multicast service, the AS sends the data of the multicast service to the PGW-U + UPF in a unicast manner, and the AS in fig. 5 and 6 sends the data of the multicast service in a multicast manner. As shown in fig. 7, the service switching method may include:

s701: terminal 1 establishes a PDU session for terminal 1.

Wherein, the transmission path of the PDU session of the terminal 1 is: AS < - > PGW-U + UPF < - > gNB < - > terminal 1. The specific execution process of S701 may refer to that described in S401, and is not described in detail.

S702: the application server sends a first subscription request to the NEF/PCF, requests subscription to notify the AS of a first event, wherein the first event is that a terminal joins a multicast session corresponding to the multicast service, and the terminal comprises a terminal 1.

The execution order of S701 and S702 is not limited, and S702 may be executed before S701 or after S701, which is not limited.

S703: the terminal 1 requests to join the multicast session to the PGW-C + SMF, and the PGW-C + SMF establishes the multicast session and joins the multicast session corresponding to the multicast service.

In this embodiment, the PGW-C + SMF may obtain the first PCC rule from the PCF, where the first PCC rule includes the first subscription request. It should be noted that, in this embodiment, it is described by taking the example that the PGW-C + SMF creates the multicast session, and if the multicast session is created by another SMF (for example, created by SMF 1), the PGW-C + SMF may acquire QoS flow information of the multicast service from SMF1, and include the first subscription request in the response message of the QoS flow including the multicast service. Or, optionally, the PGW-C + SMF sends the identification information of the terminal 1 joining the multicast session to the SMF1, and the SMF1 sends the first event notification corresponding to the first subscription request.

S704: the PGW-C + SMF determines that the terminal 1 joins the multicast session and sends a first event notification to the AS.

Wherein the first event notification is for notifying AS terminal 1 to join the multicast session. The first event notification may carry address information of the terminal 1 as well as other information. And if the first PCC rule comprises the first subscription request, the PGW-C + SMF sends a first event notification to the AS. If the response message of the QoS flow including the multicast service, which is acquired by the PGW-C + SMF from the PCF, includes the first subscription request, the PGW-C + SMF may send the first event notification to the AS, or the PGW-C + SMF may send the identification information of the terminal 1 joining the multicast session to the SMF1, and the SMF1 sends the first event notification to the AS, which is not limited.

S705: the AS receives the first event notification and sends the second description information to the PCF through the NEF.

The description of the second description information may refer to the above description, and is not repeated.

S706: and the PCF receives the second description information and formulates a second PCC rule according to the second description information.

S707: and the PGW-C + SMF acquires a second PCC rule from the PCF and determines the context of the EPS bearer corresponding to the multicast service according to the second PCC rule.

The process of determining the context of the EPS bearer corresponding to the multicast service by the PGW-C + SMF according to the second PCC rule may refer to S403, which is not described herein again.

S708: and the gNB determines that the terminal 1 is switched, switches from the 5G network to the 4G network, and sends a switching request to the AMF.

The description of the handover request and the specific execution process of S708 may refer to S404, which is not repeated herein.

S709: and the AMF receives the switching request, learns that the terminal 1 is switched according to the switching request, and sends a first message to the PGW-C + SMF to request the context information of the EPS bearer corresponding to the multicast service.

The related description of the first message and the specific execution process of S709 may refer to S405, which is not described herein.

S710: and the PGW-C + SMF receives the first message and sends the context information of the EPS bearer to the AMF.

S710 can be described with reference to S406, and is not repeated herein.

S711: and the AMF receives the context information of the EPS bearer and sends the context information of the EPS bearer to the MME.

S711 can be described with reference to S407, and is not repeated herein.

S712: and the MME receives the context information of the EPS bearer, sends a session establishment request to the SGW according to the context information of the EPS bearer and requests the SGW to establish a tunnel for each EPS bearer.

The related description of the session establishment request and the specific execution process of S712 are described with reference to S408, and are not repeated herein.

S713: and the SGW allocates the downlink tunnel information of the SGW for the EPS bearer and sends a session establishment response to the MME, wherein the session establishment response carries the downlink tunnel information of the SGW.

S714: and the MME requests the eNB to allocate radio resources and eNB downlink tunnel information for the EPS bearer.

S714 can be referred to as S409, and is not described in detail.

S715: and the eNB receives the request of the MME, allocates the radio resource for the EPS bearer and allocates the downlink tunnel information of the eNB, and carries the radio resource information of the EPS bearer in a transparent container and sends the information and the downlink tunnel information of the eNB to the MME.

S716: the MME receives the transparent container and downlink tunnel information of the eNB from the eNB and transmits the transparent container to the AMF.

S717: the AMF receives the transparent container from the MME and sends the transparent container to the gNB.

S718: and the gNB receives the transparent container and sends a switching command to the terminal 1, wherein the switching command carries the information of the radio resource carried by the EPS.

S719: the terminal 1 receives the handover command from the gNB, connects to the eNB according to the information of the radio resource carried by the EPS, and disconnects from the gNB.

S720: the eNB sends a notification message to the MME notifying the terminal 1 of the completion of the handover.

S721: and the MME receives the notification of the eNB and sends second indication information to the SGW, wherein the second indication information indicates that the terminal 1 is switched to be completed, and the second indication information carries the downlink tunnel information of the eNB received by the MME.

S722: and the SGW receives the second indication information, stores the downlink tunnel information of the eNB, and sends seventh indication information to the PGW-C + SMF according to the identification information of the PGW-C + SMF carried in the session establishment request, wherein the seventh indication information also indicates that the terminal 1 is switched to be completed, and the seventh indication information carries the downlink tunnel information of the SGW.

S723: and the PGW-C + SMF receives the seventh indication information, learns that the terminal 1 is switched, and sends a second message carrying the first mapping relation to the PGW-U + UPF. Accordingly, the PGW-U + UPF receives and stores the first mapping relationship.

The description about the first mapping relationship and the specific execution process of S723 are described with reference to S411, and it should be noted that, in the embodiment shown in fig. 7, the identification information of the multicast service flow in the first mapping relationship is used to identify the description information of one or more SDFs of the multicast service when the AS transmits in the unicast manner.

S724: and the PGW-C + SMF sends a second event notification to the AS.

S725: and the AS receives the second event notification and sends a third message to the terminal 1, wherein the third message is used for notifying the terminal 1 to receive the data of the multicast service through the EPS bearer.

Further, the AS sends a data packet carrying the address information of the terminal 1 and the data of the multicast service to the PGW-U + UPF, and the PGW-U + UPF receives the data packet and sends the data of the multicast service to the terminal 1 through the EPS bearer according to the address information of the terminal 1.

Alternatively, the second event notification described in S724 may also be sent to the AS after the PGW-C + SMF receives the first message in S710, that is, S724 and S725 may be executed in S710, or executed at any time between steps S710 to S725, which is not limited.

Subsequently, if the terminal 1 moves from the unicast zone/EPS bearer zone to the MBMS zone of the multicast service, S726 to S730 are executed.

S726: the terminal 1 detects that it enters the MBMS area of the multicast service.

The specific execution process of S726 may refer to that described in S412, and is not described in detail.

S727: the terminal 1 sends a first report to the AS.

The related description of the first report and the specific execution process of S723 may refer to S413, which are not described in detail.

S728: the AS receives the first report and sends fifth indication information to the NEF/PCF.

The description of the fifth indication information may refer to that in S414, the fifth indication information may be used to instruct the terminal 1 to stop receiving the data of the multicast service through the EPS bearer in the second network, or to notify the first network element to stop sending the data of the multicast service through the EPS bearer, or to indicate that the data of the multicast service is no longer sent through the EPS bearer, and the fifth indication information may be indication information for deleting the second description information.

S729: and the NEF/PCF receives the fifth indication information, deletes the second description information and sends third indication information to the PGW-C + SMF.

Wherein the third indication information may be indication information for deleting the second PCC rule.

S730: the PGW-C + SMF receives the third indication information, deletes the second PCC rule, deletes/releases the radio resource used for transmitting the EPS bearer corresponding to the multicast service, and sends the first configuration information to the first user plane network element, where the first configuration information may be used to notify the first user plane network element to stop/no longer send the data of the multicast service through the EPS bearer. And the first user plane network element receives the first configuration information, and stops/does not send the data of the multicast service to the SGW/target access network equipment through the EPS bearer. In the embodiment shown in fig. 7, the first configuration information may also be used to instruct the PGW-U + UPF to delete the first mapping relationship.

Further, if the terminal 1 moves from the MBMS area to the unicast area again, which results in that the data of the multicast service cannot be received through the MBMS bearer, the method further includes: the terminal 1 detects that it moves out of the MBMS area of the multicast service, sends a second report for indicating that the terminal 1 moves out of the MBMS area of the multicast service to the AS, the AS receives the second report of the terminal 1, and sends sixth indication information for indicating that the terminal 1 receives the multicast service through EPS bearer to the NEF/PCF, and the sixth indication information may carry second description information. The NEF/PCF receives the sixth indication information, and sends fourth indication information to the PGW-C + SMF, where the fourth indication information may carry the second PCC rule. And the PGW-C + SMF receives the fourth indication information and sends second configuration information to the PGW-U + UPF, wherein the second configuration information is used for informing the PGW-U + UPF to send the data of the multicast service through the EPS bearer. And after receiving the second configuration information, the PGW-U + UPF continues/sends the data of the multicast service through the EPS bearer again. In the embodiment shown in fig. 7, the second configuration information may also be used to send the first mapping relationship to the PGW-U + UPF, for example, the second configuration information may also carry the first mapping relationship, so that the PGW-U + UPF may send the received data packet of the multicast service through the corresponding EPS bearer according to the first mapping relationship.

Specifically, the description of the second report, the third indication information, the fourth indication information, the fifth indication information, the sixth indication information, and the second configuration information may refer to fig. 4, and is not repeated.

Based on the method shown in fig. 7, the PGW-C + SMF may obtain a second PCC rule corresponding to the multicast service from the PCF after the terminal 1 joins the multicast session, determine the context information of the EPS bearer according to the second PCC rule, and send the context information of the EPS bearer to the AMF when the terminal 1 is switched, so that the AMF triggers the MME to establish a tunnel of the EPS bearer, so that when the terminal 1 is switched to the second network, the AS sends the data of the multicast service to the PGW-U + SMF in a unicast manner, and the PGW-U + SMF sends the data of the multicast service to the terminal 1 through the EPS bearer, thereby ensuring continuity of multicast service transmission. Meanwhile, when the terminal 1 moves out of the area corresponding to the EPS bearer to the MBMS area, the transmission of the data of the multicast service through the EPS bearer is stopped, and the transmission of the data of the multicast service through the MBMS bearer is switched, thereby improving the data transmission performance.

Alternatively, in any embodiment shown in fig. 5 to fig. 7, after the terminal 1 enters the MBMS area of the multicast service, the terminal 1 may directly indicate to the PGW-C + SMF that the terminal 1 stops receiving the data of the multicast service through the EPS bearer in the second network. For example, taking fig. 5 as an example, S523 to S525 in fig. 5 may be replaced with:

in step (a), the terminal 1 sends eighth indication information to the PGW-C + SMF, where the eighth indication information is used to indicate to delete the EPS bearer corresponding to the multicast service, or the eighth indication information is used to indicate that the terminal 1 is receiving the multicast service through the MBMS, so that after receiving the eighth indication information, the PGW-C + SMF performs the action shown in S526.

Specifically, the description of the eighth indication information may refer to the description in fig. 4, and is not repeated.

Similarly, S625 to S627 in fig. 6 may be replaced with the above-described step (a), and S727 to S729 in fig. 7 may be replaced with the above-described step (a). It should be understood that the replacement of steps S523 to S525 in the embodiment of the present application with step (a) may refer to performing steps (a) and S526 after S522 is performed. The replacement of S625 to S627 in the embodiment of the present application with step (a) may mean that after S624 is executed, steps (a) and S628 are executed. The replacement of steps S727 to S729 in the embodiment of the present application with step (a) may mean that steps (a) and S730 are executed after step S726 is executed.

Further, when the terminal 1 moves out of the MBMS area corresponding to the service again, the terminal 1 cannot receive the data of the multicast service through the MBMS bearer. At this time, the terminal 1 may send ninth indication information to the PGW-C + SMF, where the ninth indication information is used to indicate that the terminal 1 moves out of the MBMS area of the multicast service or that the terminal 1 needs to receive the multicast service through a bearer (that is, the terminal 1 cannot receive the multicast service through an MBMS bearer) or to request to create a bearer for the multicast service, so that the GW-C + SMF deletes radio resources related to the MBMS bearer according to the ninth indication information and switches to EPS bearer to send data of the multicast service.

Specifically, the description of the ninth indication information may refer to the description in fig. 4, and is not repeated.

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 understood that each node, e.g. the first session managing network element, the application server, in order to implement the above-described functions, comprises corresponding hardware structures and/or software modules for performing the respective functions. Those skilled in the art will readily appreciate that the methods of the embodiments of the present application can be implemented in hardware, software, or a combination of hardware and computer software, in conjunction with the exemplary algorithm steps described in connection with the embodiments disclosed herein. Whether a function is performed as 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 may be divided for the first session management network element and the application server, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into 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. 8 shows a block diagram of a communication device 80, where the communication device 80 can be a first session management network element, a chip in the first session management network element, a system on chip or other devices capable of implementing the function of the first session management network element in the above method, and the communication device 80 can be used to execute the function of the first session management network element involved in the above method embodiments. As one implementation, the communication device 80 shown in fig. 8 includes: a receiving unit 801 and a transmitting unit 802;

a receiving unit 801, configured to receive a first message, which is sent from a first mobility management network element and requests an EPS bearer corresponding to a PDU session, where the first mobility management network element is in a first network, the PDU session is a PDU session of a first terminal, the PDU session is served by the first session management network element, and the PDU session is associated with a multicast service. For example, the receiving unit 801 supports the communication apparatus 80 to perform the actions of receiving the first message in S406, S506, S606, and S710.

A sending unit 802, configured to send, according to the first message, context information of an EPS bearer including a context of the EPS bearer corresponding to the multicast service to the first mobility management network element. For example, the sending unit 802 may support the communication device 80 to perform the actions of sending context information of an EPS bearer in S406, S506, S606, and S710.

Further optionally, as shown in fig. 8, the communication device 80 may further include a processing unit 803.

A processing unit 803, configured to obtain the first PCC rule through the receiving unit 801, and map the at least one SDF to the at least one EPS bearer according to the QoS parameter of the at least one SDF included in the first PCC rule, to obtain a context of the EPS bearer corresponding to the multicast service; or mapping at least one QoS stream corresponding to the multicast service to at least one EPS bearer according to the QoS stream information of the multicast service to obtain the context of the EPS bearer corresponding to the multicast service; or mapping at least one SDF corresponding to the multicast service to at least one EPS bearer according to the second PCC rule to obtain the context of the EPS bearer corresponding to the multicast service.

Further optionally, the sending unit 802 is further configured to send a first event notification to the application server, and notify the first terminal to join the multicast session corresponding to the multicast service. The receiving unit 801 is further configured to receive a second PCC rule.

Further optionally, the receiving unit 801 is further configured to receive second indication information used for indicating that the handover of the first terminal is completed. The sending unit 802 is further configured to send a second message to the first user plane network element, where the second message includes identification information of the multicast service flow and a first mapping relationship between the tunnel information of the EPS bearer, or the second message includes a second mapping relationship between an identifier of the QoS flow and the tunnel information of the EPS bearer.

Further optionally, the sending unit 802 is further configured to send a second event notification to the application server, so as to notify that the first terminal is about to switch to the second network or that the switching to the second network is completed.

Further optionally, the receiving unit 801 is further configured to receive third indication information used for indicating to stop sending data of the multicast service to the first terminal through the EPS bearer. The sending unit 802 is further configured to send, according to the third indication information, the first configuration information to the first user plane network element, and notify the first user plane network element to stop sending the data of the multicast service to the first terminal through the EPS bearer.

Further optionally, the receiving unit 801 is further configured to receive fourth indication information used for indicating that data of the multicast service is sent to the first terminal through the EPS bearer. The sending unit 802 is further configured to send, according to the fourth indication information, second configuration information to the first user plane network element, and notify the first user plane network element to send data of the multicast service to the first terminal through an EPS bearer.

Specifically, all relevant contents of each step related to the method embodiments shown in fig. 4 to fig. 7 may be referred to the functional description of the corresponding functional module, and are not described herein again. The communication device 80 is configured to perform the function of the first session managing network element in the service switching method shown in the methods shown in fig. 4-7, so that the same effect as the service switching method described above can be achieved.

In this embodiment, the communication device 80 may also be presented in a form of dividing each functional module in an integrated manner. As used herein, a "functional block" may refer to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor and memory that execute one or more software or firmware programs, an integrated logic circuit, and/or other devices that provide the described functionality. In a simple embodiment, those skilled in the art will appreciate that the communication device 80 may take the form of the communication apparatus 300 shown in fig. 3.

For example, the processor 301 in the communication device 300 shown in fig. 3 may execute the instructions by calling a computer stored in the memory 304, so that the communication device 300 executes the service switching method in the above method embodiment.

Specifically, the functions/implementation procedures of the receiving unit 801 and the sending unit 802 in fig. 8 may be implemented by the processor 301 in the communication device 300 shown in fig. 3 calling a computer executing instruction stored in the memory 304. The functions/implementation procedures of the receiving unit 801 and the transmitting unit 802 in fig. 8 may be implemented by the communication interface 303 in the communication device 300 shown in fig. 3. The functions/implementation of the processing unit 803 in fig. 8 may be implemented by the processor 301 in the communication device 300 shown in fig. 3.

Fig. 9 shows a block diagram of a communication device 90, where the communication device 90 may be an application server, a chip in the application server, a system on chip, or other devices capable of implementing the functions of the application server in the above method, and the communication device 90 may be used to execute the functions of the application server involved in the above method embodiments. As one implementation, the communication device 90 shown in fig. 9 includes: a receiving unit 901 and a transmitting unit 902;

a receiving unit 901, configured to receive a first report from a first terminal, which is used to instruct the first terminal to enter an MBMS area of a multicast service in a second network. For example, the receiving unit 901 is used to support the communication device 90 to perform the actions of receiving the first report in S413, S524, S626, and S728.

A sending unit 902, configured to send, to the first network element, fifth indication information used to indicate to stop sending data of the multicast service to the first terminal through an EPS bearer in the second network. For example, the transmitting unit 902 is configured to support the communication device 90 to perform the actions of transmitting the fifth instruction information in S413, S524, S626, and S728.

The fifth indication information may also be used to indicate the first network element to delete the second description information corresponding to the multicast service; the sixth indication information may further include second description information.

Further optionally, the receiving unit 901 is further configured to receive a second report of the first terminal, where the second report is used to indicate that the first terminal moves out of the MBMS area of the multicast service. The sending unit 902 is further configured to send sixth indication information to the first network element, where the sixth indication information indicates that the data of the multicast service is sent to the first terminal through an EPS bearer.

Further optionally, the sending unit 902 is further configured to send, to the first user plane network element through an EPS bearer, a data packet including data of the multicast service and a multicast address of the multicast service.

Further optionally, the sending unit 902 is further configured to send, to the first user plane network element through an EPS bearer, a data packet including data of the multicast service and address information of the first terminal.

Further optionally, the receiving unit 901 is further configured to receive a second event notification from the first session management network element, where the second event notification is used to notify that the first terminal is about to switch to the second network or that the handover to the second network is completed. The sending unit 902 is further configured to send a third message to the first terminal according to the second event notification, and notify the first terminal to receive the data of the multicast service through the EPS bearer.

Specifically, all relevant contents of each step related to the method embodiments shown in fig. 4 to fig. 7 may be referred to the functional description of the corresponding functional module, and are not described herein again. The communication device 80 is used to perform the function of the application server in the service switching method shown in the methods shown in fig. 4-7, so that the same effect as the service switching method described above can be achieved.

In the present embodiment, the communication device 90 is presented in a form of dividing each functional module in an integrated manner. As used herein, a "functional module" may refer to an ASIC, an electronic circuit, a processor and memory that execute one or more software or firmware programs, an integrated logic circuit, and/or other devices that provide the described functionality. In a simple embodiment, one skilled in the art will appreciate that the communication device 90 may take the form of the communication device 300 shown in fig. 3.

Specifically, the functions/implementation procedures of the receiving unit 901 and the sending unit 902 in fig. 9 can be implemented by the processor 301 in the communication device 300 shown in fig. 3 calling the computer execution instructions stored in the memory 304. The functions/implementation procedures of the receiving unit 901 and the transmitting unit 902 in fig. 9 may be implemented by the communication interface 303 in the communication device 300 shown in fig. 3.

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 relevant hardware instructed by a computer program, which may be stored in the above computer-readable storage medium, and when executed, 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 device, 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, which are provided on the terminal device. 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.

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 ways. 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 a plurality of physical units, that is, may be located in one place, or may be distributed in a plurality of 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 may be substantially or partially implemented in the form of software products, which are stored in a storage medium and include instructions for causing 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: various media capable of storing program codes, such as a U disk, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

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 for service switching, the method further comprising:

a first session management network element receives a first message from a first mobility management network element, wherein the first message is used for requesting context information of an Evolved Packet System (EPS) bearer corresponding to a Protocol Data Unit (PDU) session, the first mobility management network element is positioned in a first network, the PDU session is the PDU session of a first terminal, the PDU session is served by the first session management network element, and the PDU session is associated with a multicast service;

and the first session management network element sends the context information of the EPS bearer to the first mobility management network element according to the first message, wherein the context information of the EPS bearer comprises the context of the EPS bearer corresponding to the multicast service.

2. The method of claim 1, wherein the context of the EPS bearer comprises a context of at least one EPS bearer corresponding to the multicast service, and wherein the context of each EPS bearer comprises an identifier of the EPS bearer and a quality of service (QoS) parameter of the EPS bearer.

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

and the first session management network element determines the context of the EPS bearer corresponding to the multicast service.

4. The method of claim 3, wherein the determining, by the first session management network element, the context of the EPS bearer corresponding to the multicast service comprises:

the first session management network element determines to allow the multicast service to be switched to a second network;

5. The method of claim 4, further comprising:

and the first session management network element receives first indication information, wherein the first indication information is used for indicating that the multicast service is allowed to be switched to the second network.

6. The method according to any of claims 3-5, wherein the determining, by the first session management network element, the context of the EPS bearer corresponding to the multicast service comprises:

the first session management network element acquires a first Policy and Charging Control (PCC) rule corresponding to the multicast service, wherein the first PCC rule comprises a QoS parameter of at least one Service Data Flow (SDF) corresponding to the multicast service when an application server sends the multicast service in a multicast mode;

and the first session management network element maps the at least one SDF to the at least one EPS bearer according to the QoS parameter of the at least one SDF.

7. The method according to any of claims 3-5, wherein the determining, by the first session management network element, the context of the EPS bearer corresponding to the multicast service comprises:

the first session management network element maps at least one QoS flow corresponding to the multicast service to the at least one EPS bearer according to the QoS flow information of the multicast service;

wherein the QoS flow information comprises QoS parameters of the at least one QoS flow, and the at least one QoS flow is used for transmitting data of the multicast service in a multicast mode by an application server.

8. The method of claim 7, further comprising:

the first session management network element acquires QoS flow information of the multicast service from a second session management network element; the second session management network element is a session management network element for managing the multicast service.

9. The method of claim 3, wherein the determining, by the first session management network element, the context of the EPS bearer corresponding to the multicast service comprises:

and the first session management network element maps at least one SDF corresponding to the multicast service to the at least one EPS bearer according to a second PCC rule, wherein the second PCC rule comprises a QoS parameter of at least one service data flow SDF corresponding to the multicast service when an application server sends the multicast service in a unicast mode.

10. The method of claim 9, further comprising:

the first session management network element sends a first event notification to the application server, wherein the first event notification is used for notifying the first terminal to join a multicast session corresponding to the multicast service;

the first session managing network element receives the second PCC rule.

11. The method of claim 10, further comprising:

the first session management network element receives a first subscription request, where the first subscription request is used to request that a first event is notified to the application server, the first event is that a terminal joins in a multicast session corresponding to the multicast service, and the terminal includes the first terminal.

12. The method according to any one of claims 1-11, further comprising:

the first session management network element receives second indication information, wherein the second indication information is used for indicating that the first terminal is switched to be completed;

the first session management network element sends a second message to a first user plane network element, where the second message includes identification information of a multicast service stream and a first mapping relationship between tunnel information of the EPS bearer, the identification information of the multicast service stream is used to identify the multicast service stream corresponding to the multicast service, and the first mapping relationship is used to instruct the first user plane network element to send data of the multicast service through the EPS bearer.

13. The method according to any one of claims 1-11, further comprising:

and the first session management network element sends a second message to the first user plane network element, where the second message includes a second mapping relationship between the identifier of the QoS flow and the tunnel information of the EPS bearer, and the second mapping relationship is used to instruct the first user plane network element to send the data packet corresponding to the QoS flow through the EPS bearer.

14. The method of claim 13, wherein the second message is further used to obtain downlink tunnel information of the first user plane network element, the downlink tunnel information of the first user plane network element is used to establish a tunnel for transmitting data of the multicast service between the first user plane network element and a second user plane network element, and the second user plane network element is used to transmit the multicast service in the first network;

the method further comprises the following steps: and the first session management network element sends the downlink tunnel information of the first user plane network element to the second user plane network element.

15. The method according to any one of claims 1-14, further comprising:

and the first session management network element sends a second event notification to an application server, wherein the second event notification is used for notifying the first terminal of the completion of switching to a second network or the switching to the second network.

16. The method according to any one of claims 1-15, further comprising:

the first session management network element sends the context information of the EPS bearer to a source access network device; and/or the presence of a gas in the gas,

and the first session management network element sends the identifier of the EPS bearer, or the identifier of the EPS bearer and a packet filter of the EPS bearer to the first terminal.

17. The method according to any one of claims 1-16, further comprising:

the first session management network element receives third indication information, where the third indication information is used to indicate that data of the multicast service is stopped being sent to the first terminal through the EPS bearer;

and the first session management network element sends first configuration information to the first user plane network element according to the third indication information, where the first configuration information is used to notify the first user plane network element to stop sending the data of the multicast service to the first terminal through the EPS bearer.

18. The method according to any one of claims 1-16, further comprising:

the first session management network element receives third indication information, wherein the third indication information is used for indicating the first terminal to receive the data of the multicast service through a multicast/multicast media service MBMS bearer;

19. The method according to any one of claims 1-16, further comprising:

the first session management network element receives eighth indication information from the first terminal, where the eighth indication information is used to indicate to delete the EPS bearer, or the eighth indication information is used to indicate the first terminal to receive the data of the multicast service through an MBMS bearer;

and the first session management network element sends first configuration information to the first user plane network element according to the eighth indication information, where the first configuration information is used to notify the first user plane network element to stop sending the data of the multicast service to the first terminal through the EPS bearer.

20. The method of claim 19, further comprising:

the eighth indication information includes identification information of the multicast service.

21. The method according to any one of claims 1-20, further comprising:

the first session management network element receives fourth indication information, where the fourth indication information is used to indicate that data of the multicast service is sent to the first terminal through the EPS bearer;

and the first session management network element sends second configuration information to the first user plane network element according to the fourth indication information, where the second configuration information is used to notify the first user plane network element to send the data of the multicast service to the first terminal through the EPS bearer.

22. A method for service switching, the method comprising:

an application server receives a first report from a first terminal, wherein the first report is used for indicating the first terminal to enter a multicast/multicast media service MBMS area of a multicast service in a second network;

and the application server sends fifth indication information to the first network element, wherein the fifth indication information is used for indicating to stop sending the data of the multicast service to the first terminal through an Evolved Packet System (EPS) bearer in the second network.

23. The method of claim 22, further comprising:

the application server receives a second report of the first terminal, wherein the second report is used for indicating that the first terminal moves out of the MBMS area of the multicast service;

and the application server sends sixth indication information to the first network element, where the sixth indication information is used to indicate that the data of the multicast service is sent to the first terminal through the EPS bearer.

24. The method according to claim 22 or 23, further comprising:

and the application server sends a data packet of the multicast service to a first user plane network element through the EPS bearer, wherein the data packet of the multicast service comprises the data of the multicast service and a destination address, and the destination address comprises a multicast address of the multicast service.

25. The method of claim 24, further comprising:

the application server sends first description information of the multicast service to the first network element, where the first description information is used to formulate a first Policy and Charging Control (PCC) rule, and the first PCC rule includes a QoS parameter of at least one Service Data Flow (SDF) corresponding to the multicast service when the application server sends the multicast service in a multicast manner.

26. The method of claim 25, wherein the first description information comprises first indication information indicating that the multicast service is allowed to be handed over to the second network.

27. The method of claim 23, further comprising:

and the application server sends a data packet of the multicast service to a first user plane network element through the EPS bearer, wherein the data packet of the multicast service comprises the data of the multicast service and a destination address, and the destination address comprises the address information of the first terminal.

28. The method of claim 27,

the fifth indication information is further configured to indicate the first network element to delete second description information corresponding to the multicast service, where the second description information is description information when the multicast service is transmitted through a unicast bearer, and the second description information is used to formulate a second PCC rule corresponding to the multicast service;

the sixth indication information includes the second description information.

29. The method of claim 27 or 28, further comprising:

the application server receives a first event notification from the first network element;

and if the first event notification is used for notifying the first terminal to join the multicast session corresponding to the multicast service, the application server sends second description information corresponding to the multicast service to a first network element.

30. The method of claim 29, further comprising:

the application server sends a first subscription request to a first network element, where the first subscription request is used to request that a first event is notified to the application server, the first event is that a terminal joins a multicast session corresponding to the multicast service, and the terminal includes the first terminal.

31. The method according to any one of claims 22-30, further comprising:

the application server receives a second event notification from a first session management network element, where the second event notification is used to notify the first terminal that the handover to the second network is about to be performed or the handover to the second network is completed;

and the application server sends a third message to the first terminal according to the second event notification, wherein the third message is used for notifying the first terminal to receive the data of the multicast service through the EPS bearer.

32. The method of claim 31, further comprising:

the application server sends a second subscription request to the first network element, where the second subscription request is used to request to notify the application server of a second event, and the second event is that the first terminal is about to switch to the second network or that the switching to the second network is completed.

33. A first session managing network element, characterized in that said first session managing network element is configured to perform the service switching method according to any of claims 1 to 21.

34. An application server, characterized in that the application server is configured to execute the service switching method according to any one of claims 22 to 32.

35. A communication system, the communication system comprising: a first session management network element, a first mobility management network element;

the first mobility management network element is configured to send a first message to the first session management network element, where the first message is used to request context information of an EPS bearer corresponding to a protocol data unit PDU session; the first mobility management network element is in a first network, the PDU session is a PDU session of a first terminal, the PDU session is served by the first session management network element, and the PDU session is associated with a multicast service;

the first session management network element is configured to receive a first message, and send context information of the EPS bearer to the first mobility management network element according to the first message, where the context information of the EPS bearer includes a context of the EPS bearer corresponding to the multicast service.

36. The communication system according to claim 35, wherein the communication system further comprises an application server, a first network element;

the application server is configured to receive a first report from the first terminal, where the first report is used to instruct the first terminal to enter a multicast/multicast media service MBMS area of a multicast service in a second network, and send fifth instruction information to the first network element, where the fifth instruction information is used to instruct to stop sending data of the multicast service to the first terminal through an EPS bearer in the second network;

the first network element, configured to send, in response to the fifth indication information, third indication information to the first session management network element;

the first session management network element is configured to receive third indication information from the first network element, and send first configuration information to the first user plane network element according to the third indication information, where the third indication information is used to indicate that the sending of the data of the multicast service to the first terminal through the EPS bearer is stopped; the first configuration information is used to notify the first user plane network element to stop sending the data of the multicast service to the first terminal through the EPS bearer.

37. The communication system of claim 35, wherein the communication system further comprises a first network element;

the first network element is configured to receive fifth indication information from an application server, where the fifth indication information is used to indicate that the first terminal receives data of the multicast service through MBMS bearer;

the first session management network element is configured to receive third indication information from the first network element, and send first configuration information to the first user plane network element according to the third indication information;

the third indication information is used for indicating the first terminal to receive the data of the multicast service through MBMS bearer; the first configuration information is used to notify the first user plane network element to stop sending the data of the multicast service to the first terminal through the EPS bearer.

38. The communication system of claim 37, further comprising the application server;

the application server is configured to receive a first report from the first terminal, and send the fifth indication information to the first network element; wherein the first report is used to instruct the first terminal to enter an MBMS area in a second network.

39. The communication system according to any of claims 36-38,

the application server is further configured to receive a second report of the first terminal, where the second report is used to indicate that the first terminal moves out of the MBMS area of the multicast service; sending sixth indication information to the first network element, where the sixth indication information is used to indicate that the data of the multicast service is sent to the first terminal through the EPS bearer;

the first network element, configured to send, in response to the sixth indication information, fourth indication information to the first session management network element;

the first session management network element is further configured to receive fourth indication information, and send second configuration information to the first user plane network element according to the fourth indication information, where the fourth indication information is used to indicate that data of the multicast service is sent to the first terminal through the EPS bearer; the second configuration information is used to notify the first user plane network element to send the data of the multicast service to the first terminal through the EPS bearer.

40. The communication system of claim 35,

the first session management network element is further configured to receive eighth indication information from the first terminal, where the eighth indication information is used to indicate to delete the EPS bearer, or the eighth indication information is used to indicate that the first terminal receives the data of the multicast service through an MBMS bearer;

the first session management network element is further configured to send, according to the eighth indication information, first configuration information to the first user plane network element, where the first configuration information is used to notify the first user plane network element to stop sending the data of the multicast service to the first terminal through the EPS bearer.

41. The communication system according to any of claims 36-40,

the first session management network element is further configured to send a second event notification to the application server, where the second event notification is used to notify that the first terminal is to be switched to the second network or that the switching to the second network is completed;

the application server is further configured to receive a second event notification from a first session management network element, and send a third message to the first terminal according to the second event notification, where the third message is used to notify the first terminal to receive the data of the multicast service through the EPS bearer.