CN117641249A

CN117641249A - Multicast communication method and device

Info

Publication number: CN117641249A
Application number: CN202210950564.6A
Authority: CN
Inventors: 李濛; 张海森; 杨艳梅
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-08-09
Filing date: 2022-08-09
Publication date: 2024-03-01
Also published as: WO2024032448A1

Abstract

The application discloses a multicast communication method and device, and relates to the field of wireless communication. In the method, an access network device determines that a last terminal connected with the access network device in a multicast group leaves the access network device, and that no inactive terminal associated with the access network device exists in the multicast group, and the access network device releases a context of a multicast session of the access network device. In this way, under the condition that the terminals in the multicast group are guaranteed to receive the multicast data, the context of the multicast session corresponding to the multicast group can be released in time, so that resources are saved.

Description

Multicast communication method and device

Technical Field

The present disclosure relates to the field of wireless communications, and in particular, to a multicast communication method and apparatus.

Background

In a communication system, after an access network device switches a terminal in a multicast group from a radio resource control connected (radio resource control connected, RRC-connected) state (hereinafter referred to as a connected state) to a radio resource control inactive (radio resource controlinactive, RRC-inactive) state (hereinafter referred to as an inactive state), the terminal may move, for example, from a coverage area of the access network device to a coverage area of another access network device. Since the other access network device does not establish the context of the multicast session corresponding to the multicast group, the terminal cannot receive the multicast data of the multicast group through the other access network device.

In order to solve the above problems, a solution is proposed: a plurality of access network devices within a certain area establish a context of a multicast session corresponding to the multicast group. However, this solution introduces a new technical problem, namely how the access network devices in the certain area maintain the context of the multicast session corresponding to the multicast group when the terminal is restored from the inactive state to the connected state.

Disclosure of Invention

The embodiment of the application provides a multicast communication method and a device, so that when a terminal in a multicast group is recovered from an inactive state to a connection state, an access network device can timely release the context of a multicast session corresponding to the multicast group.

In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions:

in a first aspect, a multicast communication method is provided, and a communication device performing the method may be a first access network device; or may be a module, such as a chip or a chip system, applied in the first access network device. The following describes an example in which the execution body is a first access network device. The method comprises the following steps: determining that a last terminal connected with first access network equipment in a multicast group leaves the first access network equipment, and releasing the context of a multicast session of the first access network equipment when no terminal in an inactive state associated with the first access network equipment exists in the multicast group. The multicast session is used for transmitting multicast data corresponding to the multicast group. In this embodiment of the present application, there is no inactive terminal associated with the first access network device in the multicast group, and other description manners may be replaced, for example, the coverage area of the first access network device and the radio access network (radio access network, RAN) notification area (RAN notification area, RNA) of any terminal in the multicast group do not have an intersection, or the coverage area of the first access network device is not included in the RNA of any terminal in the multicast group, or the access network device in the RNA of any terminal in the multicast group does not include the first access network device, or the coverage area of the first access network device and the RNA of any terminal in the multicast group do not have a common cell or tracking area, or the cell or tracking area corresponding to the RNA of any terminal in the multicast group does not belong to the first access network device.

Based on the method provided in the first aspect, in the case that the last terminal connected with the first access network device in the multicast group leaves the first access network device and the terminal in the inactive state associated with the first access network device does not exist in the multicast group, the first access network device releases the context of the multicast session corresponding to the multicast group, so that not only can the terminal in the multicast group be ensured to receive the multicast data, but also the access network device can timely release the context of the multicast session corresponding to the multicast group, so as to save resources.

In one possible implementation, the method further includes: a multicast session leave message is sent to the second network device to trigger release of the context of the multicast session of the second network device. The second network device may be an AMF network element, an MB-SMF network element, a UPF network element or an access network device other than the first access network device.

Based on the possible implementation manner, the second network device may be triggered to release the context of the multicast session corresponding to the multicast group.

In one possible implementation, after determining that a last terminal in the multicast group connected to the first access network device leaves the first access network device and that there is no inactive terminal in the multicast group associated with the first access network device, the method further includes: transmitting a request message to the first network device, the request message being for requesting release of the multicast session; before releasing the context of the multicast session of the first access network device, the method further comprises: a response message is received from the first network device, the response message being for responding to the request message. The second network device may be an AMF network element, an MB-SMF network element, a UPF network element or an access network device other than the first access network device.

Based on the possible implementation manner, the first network device may be enabled to release the multicast session corresponding to the multicast group.

In one possible implementation, a last terminal in the multicast group connected to the first access network device leaves the first access network device, including: the last terminal in the multicast group connected to the first access network device is deleted from the context of the multicast session by the first access network device; or, the last terminal in the multicast group connected to the first access network device is handed over to an access network device other than the first access network device.

Based on the possible implementation manner, in a case that a last terminal connected to the first access network device in the multicast group is deleted by the first access network device from the context of the multicast session, the first access network device determines that the last terminal connected to the first access network device in the multicast group leaves the first access network device. Or, in the case that the last terminal connected to the first access network device in the multicast group is handed over to an access network device other than the first access network device, the first access network device determines that the last terminal connected to the first access network device in the multicast group leaves the first access network device.

In one possible implementation, determining that a last terminal in a multicast group connected to the first access network device leaves the first access network device includes: and determining that the last terminal connected with the first access network equipment in the multicast group leaves the first access network equipment according to the first information of the terminal in the connection state associated with the first access network equipment in the multicast group.

Based on the possible implementation manner, the first access network device may determine whether a last terminal connected to the first access network device in the multicast group leaves the first access network device according to the first information of the terminal in the connection state associated with the first access network device in the multicast group.

In one possible implementation manner, the first information is used to indicate the number of terminals in the multicast group that are connected to the first access network device and are in a connection state, or the first information is used to indicate the number of contexts of the terminals in the multicast group stored in the first access network device, or the first information is used to indicate whether the contexts of the terminals in the multicast group are stored in the first access network device.

Based on the possible implementation manner, the first access network device may determine whether the last terminal connected to the first access network device in the multicast group leaves the first access network device according to the number of terminals connected to the first access network device in the multicast group. Alternatively, the first access network device may determine whether a last terminal in the multicast group connected to the first access network device has left the first access network device according to the number of contexts of the terminals in the multicast group stored in the first access network device. Alternatively, the first access network device may determine whether the last terminal in the multicast group connected to the first access network device has left the first access network device based on whether the first access network device stores the context of the terminal in the multicast group.

In one possible implementation, determining that there is no inactive terminal associated with the first access network device in the multicast group includes: and determining that the terminal in the inactive state associated with the first access network equipment does not exist in the multicast group according to the second information of the terminal in the inactive state associated with the first access network equipment in the multicast group.

Based on the possible implementation manner, the first access network device may determine whether the inactive state terminal associated with the first access network device exists in the multicast group according to the second information of the inactive state terminal associated with the first access network device in the multicast group.

In one possible implementation, the inactive state of the terminal associated with the first access network device in the multicast group includes: a terminal in the multicast group switched to an inactive state by the first access network device; and a terminal in the multicast group switched to an inactive state by an access network device other than the first access network device, and a radio access network notification area of the terminal includes all or a part of a coverage area of the first access network device.

Based on the possible implementation manner, in the case that the first access network device switches the terminal in the multicast group to the inactive state, the first access network device may determine that the terminal is a terminal in the multicast group in the inactive state associated with the first access network device. Alternatively, in the case where the terminal in the multicast group is switched to the inactive state by the other access network devices except the first access network device, and the radio access network notification area of the terminal includes all or part of the coverage area of the first access network device, the first access network device may determine that the terminal is the inactive state terminal associated with the first access network device in the multicast group. I.e. the possible implementations described above provide a method for the first access network device to determine a terminal in the multicast group in an inactive state associated with the first access network device.

In one possible implementation, the method further includes: receiving first notification information from a second access network device, where the first notification information is used to notify that one terminal in the multicast group is switched to an inactive state, or the first notification information is used to notify that a terminal in the multicast group that is switched to an inactive state by the second access network device exists, or the first notification information is used to notify the number of terminals in the multicast group that is switched to an inactive state by the second access network device; and updating the second information according to the first notification information.

Based on the possible implementation manner, the first access network device may update the second information in a case that the terminal in the multicast group is switched to the inactive state, or in a case that the terminal in the multicast group is switched to the inactive state by the second access network device. For example, if the second information indicates the number of inactive terminals associated with the first access network device in the multicast group, the first access network device increases the number indicated by the second information by 1. Or if the second information indicates the number of times of use of the context of the multicast session, the first access network device increases the number of times indicated by the second information by 1.

In one possible implementation, the method further includes: receiving second notification information from the second access network device, where the second notification information is used to notify that one terminal in the multicast group leaves an inactive state, or the second notification information is used to notify that no terminal switched to the inactive state by the second access network device exists in the multicast group, or the second notification information is used to notify the number of terminals that leave the inactive state under the second access network device in the multicast group; and updating the second information according to the second notification information.

Based on the possible implementation manner, the first access network device may update the second information when the terminal in the multicast group leaves the inactive state, or when there is no terminal in the multicast group switched to the inactive state by the second access network device. For example, if the second information indicates the number of inactive terminals associated with the first access network device in the multicast group, the first access network device decreases the number indicated by the second information by 1. Or if the second information indicates the number of times of use of the context of the multicast session, the first access network device decreases the number of times indicated by the second information by 1.

In one possible implementation, the second information is used to indicate a number of inactive terminals associated with the first access network device in the multicast group, or the second information is used to indicate a number of uses of a context of the multicast session.

Based on the possible implementation manner, the first access network device may determine whether the inactive state terminal associated with the first access network device exists in the multicast group by calculating the number of inactive state terminals associated with the first access network device in the multicast group. Alternatively, the first access network device may determine whether there are non-active terminals associated with the first access network device in the multicast group by counting the number of uses of the context of the multicast session. In the embodiment of the present application, the number of times the context of the multicast session is used may be understood as the number of times the context of the multicast session is established. For example, if the other access network device requests the first access network device to establish the context of the multicast session corresponding to the multicast group, the number of times of using the context of the multicast session increases, and if the other access network device requests the first access network device to release the context of the multicast session corresponding to the multicast group, the number of times of using the context of the multicast session decreases.

In one possible implementation manner, determining that the terminal in the inactive state associated with the first access network device does not exist in the multicast group according to the second information of the terminal in the inactive state associated with the first access network device in the multicast group includes: and when the number of the terminals indicated by the second information is zero or the number of times indicated by the second information is zero, determining that no inactive terminal associated with the first access network device exists in the multicast group.

Based on the possible implementation manner, in the case that the number of terminals indicated by the second information is zero or the number of times indicated by the second information is zero, the first access network device may determine that there is no terminal in the multicast group in an inactive state associated with the first access network device.

In one possible implementation, the method further includes: if a first terminal in the multicast group is switched to a non-activated state, third notification information is sent to at least one access network device, wherein the third notification information is used for notifying that one terminal in the multicast group is switched to the non-activated state, or the third notification information is used for notifying that a terminal switched to the non-activated state by the first access network device exists in the multicast group.

Based on the possible implementation manner, in the case that one terminal in the multicast group is switched to the inactive state, or in the case that a terminal switched to the inactive state by the first access network device exists in the multicast group, the first access network device may notify at least one access network device, so that each access network device in the at least one access network device updates the second information of the terminal in the multicast group associated with the terminal in the inactive state according to the third notification information.

In one possible implementation, the first terminal is a terminal in the multicast group that is switched to an inactive state by the first access network device.

Based on the possible implementation manner, in the case that the first access network device switches the first terminal in the multicast group to the inactive state, the first access network device sends third notification information to at least one access network device, so that each access network device in the at least one access network device updates the second information of the terminal in the multicast group associated with the second terminal in the inactive state according to the third notification information.

In one possible implementation, the method further includes: under the condition that the first terminal is recovered from an inactive state to a connected state under the first access network equipment, fourth known information is sent to the at least one access network equipment, and the fourth known information is used for notifying one terminal in the multicast group to leave the inactive state; or, in the case that the first terminal leaves the active state from the third access network device, sending fifth notification information to the access network devices except for the third access network device in the at least one access network device, where the fifth notification information is used to notify that one terminal in the multicast group leaves the inactive state.

Based on the possible implementation manner, in the case that the first terminal is restored from the inactive state to the connected state under the first access network device, the first access network device may send fourth notification information to at least one access network device, so that each access network device in the at least one access network device updates, according to the fourth notification information, the second information of the terminal in the multicast group associated with the terminal in the inactive state maintained by the first access network device. Or under the condition that the first terminal leaves the active state from the third access network equipment, the first access network equipment sends fifth notification information to the access network equipment except the third access network equipment in at least one access network equipment, so that the access network equipment receiving the fifth notification information can update the second information of the terminal in the non-active state associated with the multicast group maintained by the access network equipment according to the fifth notification information, and further determine whether to release the context of the multicast session established for the multicast group.

In one possible implementation, in a case where the first terminal is restored to the connected state from the inactive state under the first access network device, and the multicast group is switched to the inactive state by the first access device, and the coverage area of at least one access network device is not included in the radio access network notification area of each terminal that is currently still in the inactive state, fourth notification information is sent to the at least one access network device.

Based on the possible implementation manner, signaling overhead of the first access network device can be reduced.

In one possible implementation, in a case where the first terminal leaves the active state from the third access network device and is switched to the inactive state by the first access device in the multicast group, and the radio access network notification area of each terminal that is currently still in the inactive state does not include a coverage area of an access network device other than the third access network device in the at least one access network device, fifth notification information is sent to the access network device other than the third access network device in the at least one access network device.

In one possible implementation, the method further includes: and when the last terminal in the multicast group, which is switched to the inactive state by the first access network device, leaves the inactive state, sending sixth notification information to the at least one access network device, wherein the sixth notification information is used for notifying that the number of the terminals, which are switched to the inactive state by the first access network device, in the multicast group is 0, or the sixth notification information is used for notifying that no terminal, which is switched to the inactive state by the first access network device, exists in the multicast group.

Based on the possible implementation manner, when the last terminal in the multicast group, which is switched to the inactive state by the first access network device, leaves the inactive state, sixth notification information is sent to at least one access network device, so that each access network device in the at least one access network device updates second information of the inactive state terminal associated with the multicast group maintained by the access network device according to the sixth notification information, and further, whether to release the context of the multicast session established for the multicast group by itself is determined.

In a second aspect, a multicast communication method is provided, and a communication apparatus performing the method may be a second access network device; or may be a module, such as a chip or a system of chips, applied in the second access network device. The following describes an example in which the execution body is the second access network device. The method comprises the following steps: establishing a context of a multicast session of the second access network device, where the multicast session is used to transmit multicast data corresponding to the multicast group; receiving a first message from a first access network device, the first message indicating to release a context of the multicast session; the context of the multicast session is released.

Based on the method provided in the second aspect, after the second access network device establishes the context of the multicast session of the second access network device, a message indicating to release the context of the multicast session from the first access network device may be received, and the context of the multicast session may be timely released according to the message.

In one possible implementation, the method further includes: a second message is received from the first access network device requesting the second access network device to establish a context for the multicast session.

Based on the possible implementation manner, the second access network device may establish a context of the multicast session of the second access network device according to the second message.

In one possible implementation, releasing the context of the multicast session includes: and releasing the context of the multicast session when the last terminal connected with the second access network device in the multicast group leaves the second access network device and no non-active terminal associated with the second access network device exists in the multicast group.

Based on the possible implementation manner, the second access network device may release the context of the multicast session when the last terminal connected to the second access network device in the multicast group leaves the second access network device and there is no terminal in the multicast group in an inactive state associated with the second access network device. In this way, the access network device which needs to send data to the terminal in the multicast group can keep the context of the multicast session corresponding to the multicast group, so as to ensure that the terminal in the multicast group can receive the multicast data, and the access network device which does not need to send data to the terminal in the multicast group can timely release the context of the multicast session corresponding to the multicast group, so as to save resources.

In a third aspect, a multicast communication method is provided, and a communication apparatus performing the method may be a first access network device; or may be a module, such as a chip or a chip system, applied in the first access network device. The following describes an example in which the execution body is a first access network device. The method comprises the following steps: sending a second message to a second access network device, where the second message is used to request to establish a context of a multicast session of the second access network device, and the multicast session is used to transmit multicast data corresponding to a multicast group; and/or sending a first message to the second access network device, the first message being used to indicate to release the context of the multicast session.

Based on the method provided in the third aspect, the first access network device instructs the second access device to establish or release the context of the multicast session.

In one possible implementation, sending the first message to the second access network device includes: if the radio access network notification area of each terminal in the multicast group, which is switched to the inactive state by the first access network device and is still in the inactive state at present, does not include the coverage area of the second access network device, the first message is sent to the second access network device; or if the first access network device receives a third message from a third access network device, the third message is used for indicating that a terminal in the multicast group, which is switched to an inactive state by the first access network device, is restored to a connection state at the third access network device, or the third message is used for requesting the first access network device to send a context of the terminal to the third access network device and sending the first message to the second access network device.

Based on the possible implementation manner, in the case that the coverage area of the second access network device is not included in the radio access notification area of each terminal that is switched to the inactive state by the first access network device in the multicast group and is still in the inactive state, the first access network device sends a first message to the second access network device, so as to reduce signaling overhead of the first access network device. Or after receiving the third message of the third access network device, sending the first message to the second access network device to inform the second access network device that one terminal in the multicast group leaves the inactive state.

In a fourth aspect, a communication device is provided for implementing the method provided in the first aspect. The communication means may be or comprise the access network device of the first aspect. The communication device comprises corresponding modules, units or means (means) for implementing the above method, where the modules, units or means may be implemented by hardware, software, or implemented by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

In one possible implementation, the communication device may include a processing module. Optionally, the communication device further comprises a transceiver module. The processing module may be configured to implement the processing functions of the first aspect and any possible implementation manner thereof. The processing module may be, for example, a processor. The transceiver module, which may also be referred to as a transceiver unit, is configured to implement the transmitting and/or receiving functions of the first aspect and any possible implementation manner thereof. The transceiver module may be formed by a transceiver circuit, transceiver or communication interface.

In a possible implementation manner, the transceiver module includes a transmitting module and a receiving module, which are respectively configured to implement the transmitting and receiving functions in the first aspect and any possible implementation manner thereof.

In one possible implementation, the processing module is configured to determine that a last terminal connected to the communication device in the multicast group leaves the communication device, and that there is no inactive terminal associated with the communication device in the multicast group, and the processing module is further configured to release a context of a multicast session of the communication device, where the multicast session is used to transmit multicast data corresponding to the multicast group.

In one possible implementation, the transceiver module is configured to send a request message to the first network device, where the request message is configured to request release of the multicast session; the transceiver module is further configured to receive a response message from the first network device, where the response message is used to respond to the request message.

In one possible implementation, the transceiver module is further configured to send a multicast session leave message to the second network device, where the multicast session leave message is used to trigger to release a context of a multicast session of the second network device, and the multicast session of the second network device is used to transmit multicast data corresponding to the multicast group.

In one possible implementation, the last terminal in the multicast group connected to the communication device leaves the communication device, including: the last terminal in the multicast group to which the communication device is connected is deleted by the communication device from the context of the multicast session; or, the last terminal in the multicast group connected to the communication apparatus is handed over to an access network device other than the communication apparatus.

In one possible implementation manner, the processing module is specifically configured to determine that a last terminal connected to the communication device in the multicast group leaves the communication device according to first information of a terminal in a connection state associated with the communication device in the multicast group.

In one possible implementation, the first information is used to indicate the number of terminals in the multicast group that are connected to the communication device and in a connected state, or the first information is used to indicate the number of contexts of the terminals in the multicast group stored in the communication device.

In one possible implementation manner, the processing module is specifically configured to determine that the inactive terminal associated with the communication device does not exist in the multicast group according to the second information of the inactive terminal associated with the communication device in the multicast group.

In one possible implementation, the inactive state of the terminal associated with the communication device in the multicast group includes: a terminal in the multicast group switched to an inactive state by the communication device; and a terminal in the multicast group switched to an inactive state by other access network devices than the communication apparatus, and a radio access network notification area of the terminal includes all or a part of a coverage area of the communication apparatus.

In one possible implementation manner, the transceiver module is further configured to receive first notification information from a second access network device, where the first notification information is used to notify that one terminal in the multicast group is switched to an inactive state, or the first notification information is used to notify that there are terminals in the multicast group that are switched to an inactive state by the second access network device, or the first notification information is used to notify that the number of terminals in the multicast group that are switched to an inactive state by the second access network device; the processing module is further configured to update the second information according to the first notification information.

In one possible implementation manner, the transceiver module is further configured to receive second notification information from the second access network device, where the second notification information is used to notify that one terminal in the multicast group leaves an inactive state, or the second notification information is used to notify that no terminal switched to the inactive state by the second access network device exists in the multicast group, or the second notification information is used to notify the number of terminals leaving the inactive state under the second access network device in the multicast group; the processing module is further configured to update the second information according to the second notification information.

In one possible implementation, the second information is used to indicate a number of inactive terminals associated with the communication device in the multicast group, or the second information is used to indicate a number of uses of a context of the multicast session.

In a possible implementation manner, the processing module is specifically configured to determine that there is no inactive terminal associated with the communication device in the multicast group when the number of terminals indicated by the second information is zero or the number of times indicated by the second information is zero.

In one possible implementation manner, the transceiver module is further configured to send third notification information to at least one access network device if the first terminal in the multicast group is switched to the inactive state, where the third notification information is used to notify that one terminal in the multicast group is switched to the inactive state, or the third notification information is used to notify that there is a terminal in the multicast group that is switched to the inactive state by the communication device.

In one possible implementation, the first terminal is a terminal in the multicast group that is switched to an inactive state by the communication device.

In a possible implementation manner, the transceiver module is further configured to send fourth notification information to the at least one access network device, where the first terminal returns from the inactive state to the connected state under the communication device, where the fourth notification information is used to notify that one terminal in the multicast group leaves the inactive state; or the transceiver module is further configured to send fifth notification information to an access network device other than the third access network device in the at least one access network device, where the first terminal leaves the active state from the third access network device, where the fifth notification information is used to notify that one terminal in the multicast group leaves the inactive state.

In one possible implementation manner, the transceiver module is further configured to send, when a last terminal in the multicast group of the terminals switched to the inactive state by the communication device leaves the inactive state, sixth notification information to the at least one access network device, where the sixth notification information is used to notify that the number of terminals in the multicast group that are switched to the inactive state by the communication device is 0, or the sixth notification information is used to notify that there are no terminals in the multicast group that are switched to the inactive state by the communication device.

In a fifth aspect, a communication device is provided for implementing the method provided in the second aspect. The communication means may be or comprise the access network device of the second aspect. The communication device comprises corresponding modules, units or means (means) for implementing the above method, where the modules, units or means may be implemented by hardware, software, or implemented by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

In one possible implementation, the communication device may include a processing module and a transceiver module. The processing module may be adapted to implement the processing functions of the second aspect and any possible implementation thereof. The processing module may be, for example, a processor. The transceiver module, which may also be referred to as a transceiver unit, is configured to implement the transmitting and/or receiving functions of the second aspect and any possible implementation thereof. The transceiver module may be formed by a transceiver circuit, transceiver or communication interface.

In one possible implementation manner, the transceiver module includes a transmitting module and a receiving module, which are respectively configured to implement the transmitting and receiving functions in the second aspect and any possible implementation manner thereof.

In one possible implementation, the processing module is configured to establish a context of a multicast session of the communication device, where the multicast session is used to transmit multicast data corresponding to a multicast group; a transceiver module configured to receive a first message from a first access network device, the first message being configured to indicate to release a context of the multicast session; and the processing module is also used for releasing the context of the multicast session.

In one possible implementation, the transceiver module is further configured to receive a second message from the first access network device, where the second message is used to request the communication apparatus to establish the context of the multicast session.

In one possible implementation, the processing module is specifically configured to release the context of the multicast session when a last terminal in the multicast group connected to the communication device leaves the communication device and there is no inactive terminal associated with the communication device in the multicast group.

In a sixth aspect, a communication device is provided for implementing the method provided by the third aspect. The communication means may be or comprise the access network device of the third aspect. The communication device comprises corresponding modules, units or means (means) for implementing the above method, where the modules, units or means may be implemented by hardware, software, or implemented by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

In one possible implementation, the communication device may include a transceiver module. The transceiver module, which may also be referred to as a transceiver unit, is configured to implement the transmitting and/or receiving functions of the third aspect and any possible implementation thereof. The transceiver module may be formed by a transceiver circuit, transceiver or communication interface.

In a possible implementation manner, the transceiver module includes a transmitting module and a receiving module, which are respectively configured to implement the transmitting and receiving functions in the third aspect and any possible implementation manner thereof.

In one possible implementation manner, the transceiver module is configured to send a second message to a second access network device, where the second message is used to request to establish a context of a multicast session of the second access network device, and the multicast session is used to transmit multicast data corresponding to a multicast group; and/or; the transceiver module is further configured to send a first message to the second access network device, where the first message is used to indicate to release the context of the multicast session.

In a possible implementation manner, the transceiver module is specifically configured to send the first message to the second access network device if the coverage area of the second access network device is not included in the radio access network notification area of each terminal in the multicast group that is switched to the inactive state by the communication device and is still in the inactive state currently; or, the transceiver module is specifically configured to, if the communication apparatus receives a third message from a third access network device, instruct a terminal in the multicast group that is switched to an inactive state by the communication apparatus to restore to a connection state at the third access network device, or request the communication apparatus to send a context of the terminal to the third access network device, and send the first message to the second access network device.

In a seventh aspect, there is provided a communication apparatus comprising: a processor; the processor is configured to couple to the memory and to execute the method according to any of the above aspects in response to the instructions after reading the instructions in the memory. The communication means may be the first access network device of the first aspect or a device comprising the first access network device; alternatively, the communication means may be the second access network device of the second aspect, or a device comprising the second access network device; alternatively, the communication means may be the first access network device of the third aspect or a device comprising the first access network device.

With reference to the seventh aspect, in a possible implementation manner, the communication device further includes a memory, where the memory is used to store necessary program instructions and data.

With reference to the seventh aspect, in one possible implementation manner, the communication device is a chip or a chip system. Alternatively, when the communication device is a chip system, the communication device may be formed by a chip, or may include a chip and other discrete devices.

An eighth aspect provides a communication apparatus comprising: a processor and interface circuit; interface circuit for receiving computer program or instruction and transmitting to processor; the processor is configured to execute the computer program or instructions to cause the communication device to perform the method as described in any of the above aspects.

With reference to the eighth aspect, in one possible implementation manner, the communication device is a chip or a chip system. Alternatively, when the communication device is a chip system, the communication device may be formed by a chip, or may include a chip and other discrete devices.

In a ninth aspect, there is provided a computer readable storage medium having instructions stored therein which, when run on a computer, cause the computer to perform the method of any of the above aspects.

In a tenth aspect, there is provided a computer program product containing instructions which, when run on a computer, cause the computer to perform the method of any of the above aspects.

The technical effects caused by any one of the possible implementation manners of the fourth aspect to the tenth aspect may be referred to any one of the above first aspect to the third aspect or the technical effects caused by any one of the different possible implementation manners of the first aspect to the third aspect, which are not repeated herein.

In an eleventh aspect, a communication system is provided, the communication system comprising an access network device and a network device, wherein the access network device is configured to perform the method of the first aspect described above, and the network device is configured to receive a multicast session leave message from the access network device.

In one possible implementation, the network device comprises a core network device or an access network device other than the access network device.

In a twelfth aspect, a communication system is provided, the communication system comprising a second access network device for performing the method according to the second aspect described above, and a first access network device for performing the method according to the third aspect described above.

It will be appreciated that the above aspects may be combined without contradiction between the aspects.

Drawings

FIG. 1 is a schematic diagram of a communication system architecture;

fig. 2 is a schematic hardware structure of a communication device according to an embodiment of the present application;

fig. 3A is a schematic flow chart of a multicast communication method according to an embodiment of the present application;

fig. 3B is a second flowchart of a multicast communication method according to an embodiment of the present application;

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

fig. 5 is a flow chart diagram of a multicast communication method according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of a communication device according to an embodiment of the present application;

fig. 7 is a schematic structural diagram of a communication device according to an embodiment of the present application.

Detailed Description

Before describing the embodiments of the present application, technical terms and related processes related to the embodiments of the present application are described. It will be appreciated that these descriptions are intended to provide an easier understanding of the embodiments of the present application, and should not be construed as limiting the scope of protection claimed by the embodiments of the present application.

1. Connection state, inactive state, and radio resource control idle (radio resource control idle, RRC-idle) state (hereinafter referred to as idle state)

In the connected state, there is a radio resource control (radio resource control, RRC) connection between the terminal and the access network device, where the access network device knows that the terminal is within the coverage area of the access network device, or further, where the access network device knows that the terminal is in a cell corresponding to the access network device, and where the core network device knows that the terminal can be found through the access network device. The terminal may receive downlink data and signaling from the access network device, and may also send uplink data and signaling to the access network device. The coverage area of an access network device includes the area where the access network device is capable of providing access services to a terminal, which may also be referred to as the service coverage area of the access network device or the service area of the access network device.

In the inactive state, no RRC connection exists between the terminal and the access network device, the access network device may not know whether the terminal is within the coverage area of the access network device, and the core network device considers that the terminal is still in a Connected state (CM-Connected state), and downlink data and signaling of the terminal are sent to the access network device as in the Connected state.

In idle state, there is no RRC connection between the terminal and the access network device, the access network device is not aware of the existence of the terminal, and the core network device may not be aware of which access network device the terminal can be found through.

2. Radio access network (radio access network, RAN) notification area (RAN notification area, RNA)

The RNA may also be referred to as a RAN-based notification area (RAN-based notification area), a RAN notification area, or the like, without limitation. The RNAs may be areas set by the access network device for the terminals in the inactive state in the multicast group, that is, the terminals in the inactive state in the multicast group may correspond to one RNA. The RNA may indicate a plurality of cells (cells) or at least one access network device, e.g., the RNA includes an identification of a plurality of cells, or a list of cells, or a Tracking Area (TA) or at least one access network device. The terminal may move within the cell indicated by the RNA or within the coverage area of the indicated access network device without interaction with the network. If the core network has downlink data or signaling to be sent to the terminal, the access network device in the RNA can page the terminal, so that the terminal enters a connection state to receive the downlink data or signaling.

The access network device in the RNA may be understood as including all or part of the coverage area of the access network device in the RNA, or may be understood as the access network device to which each cell included in the RNA belongs (or corresponds).

For example, if the RNA includes cell 1, cell 2, and cell 3, where cell 1 and cell 2 are cells of the access network device 1 and cell 3 is a cell of the access network device 2, then the access network device in the RNA includes the access network device 1 and the access network device 2.

For another example, if the RNA includes the TA of the access network device 1, the TA of the access network device 2, and the TA of the access network device 3, the access network device within the RNA includes the access network device 1, the access network device 2, and the access network device 2.

For another example, if the RNA includes an identification of the access network device 1 and an identification of the access network device 2, the access network device within the RNA includes the access network device 1 and the access network device 2.

The Cell may be a new air interface Cell identifier (NR Cell Identity), or a new air interface Cell global identifier (NR Cell Global Identity), which will be described in detail herein.

3. Flow of terminal joining multicast group (also understood as joining multicast session corresponding to multicast group)

S11: the terminal sends a first request to a session management function (session management function, SMF) network element.

Accordingly, the SMF network element receives a first request from the terminal.

The first request may be used to request to join a multicast group of the multicast service, or join a multicast session corresponding to the multicast group. The first request may include information of the multicast group or information of the multicast session.

Wherein the information of the multicast group may include an identification of the multicast group or a protocol address associated with the multicast service.

In particular, the identification of the multicast group may be used to indicate the multicast group. In particular, the identification of the multicast group may be a temporary identification, e.g. a temporary mobile group identification (temporary mobile group identifier, TMGI), of the application server (application server, AS) or the fifth generation (5th generation,5G) core network allocated for the multicast group.

In particular, the protocol address associated with the multicast service may be an internet protocol (Internet Protocol, IP) address, for example, an IP address of the multicast data, or an IP address of a user plane function (user plane function, UPF) network element connected to the AS. Optionally, the information of the multicast group may further include a port number of a UPF network element connected to the AS. Or the multicast traffic related protocol address may be a source specific multicast address (Source Specific Multicast address).

The information of the multicast session may include an identification of the multicast session corresponding to the multicast group. The identification of the multicast session may be used to identify the multicast session. The multicast session corresponding to the multicast group is used for transmitting the multicast data corresponding to the multicast group.

It should be noted that, in the embodiment of the present application, the multicast group may be replaced by a multicast session, which is used to transmit multicast data corresponding to the multicast group.

One possible implementation, the first request is included in a non-access stratum (non access stratum, NAS) message or in a join request message of the user plane. The NAS message may be a protocol data unit (protocol data unit, PDU) session modification request, a PDU session establishment request, or the like. The join request message of the user plane may be an internet group management protocol (internet group management protocol, IGMP) join message (IGMP join message).

One possible implementation manner, the application of the terminal triggers the terminal to send a first request to the SMF network element; or if the terminal detects that the data needs to be received or sent in a multicast mode, the terminal sends a first request to the SMF network element.

S12: the SMF network element sends a first message to the access network device.

Accordingly, the access network device receives a first message from the SMF network element.

Wherein the first message includes a context of a multicast session corresponding to the multicast group.

Optionally, the first message further includes information of a unicast quality of service (quality of service, qoS) flow (QoS flow) corresponding to the multicast group.

In one possible implementation manner, after the SMF network element receives the first request, multicast information is obtained. For example, the SMF network element obtains multicast information from a multicast broadcast session management function (multicast/broadcast-session management function, MB-SMF) network element or a unified data repository (unified data repository, UDR) network element based on the identification of the multicast group or the information of the multicast session. Wherein the multicast information may include QoS information of the multicast session. The SMF network element generates the context of the multicast session according to the multicast information.

Wherein the context of the multicast session will be presented in the fourth point below.

Optionally, the SMF network element further generates unicast QoS flow information corresponding to the multicast group according to the multicast information.

S13: the access network device establishes or modifies the context of the multicast session corresponding to the multicast group according to the first message.

It will be appreciated that after S13, the terminal successfully joins the multicast group, and the terminal may receive multicast data of the multicast group through the access network device.

It may be appreciated that in the embodiment of the present application, the context of the access network device establishing the multicast session corresponding to the multicast group may be understood as: the access network device establishes a transmission channel for transmitting multicast data between the access network device and a UPF network element (e.g., a multicast broadcast user plane function network element), or the access network device allocates an identifier (e.g., a transmission tunnel identifier) for the transmission channel for transmitting multicast data between the access network device and the UPF network element. Further, the access network device may send the identification to the MB-SMF network element. After receiving the identifier, the MB-SMF network element may send the identifier to the UPF network element.

It is understood that in the embodiments of the present application, a transmission channel may alternatively be described as a transmission logical channel, a communication connection, a transmission path, a tunnel, or a transmission tunnel, etc. Multicast may be replaced with terms broadcast (broadcast), multicast (multicast), multicast/broadcast, etc.

It will be appreciated that the terminal may receive multicast data for a multicast group after joining the multicast group or multicast session, i.e., the terminal is in a connected state. Subsequently, the access network device may release the RRC connection with the terminal, so that the terminal switches to the inactive state. Subsequently, the terminal receives the multicast data of the multicast group in an inactive state.

4. Context of multicast sessions

The context of the multicast session may include one or more of the following information: the identification information of the transmission channel of the multicast session, the QoS information of the multicast session, the status information of the multicast session, the area identification of the MBS or the identification information of the terminal corresponding to the multicast session.

Wherein the identification information of the transmission channel of the multicast session is used to identify the transmission channel of the multicast session, the transmission channel may include at least one of: a channel between the access network device and the UPF network element for transmitting multicast data corresponding to the multicast session, or a channel between the two access network devices for transmitting multicast data corresponding to the multicast session. In particular, the identification information may include a tunnel endpoint identification for multicast session transmission, such as: multicast/broadcast session tunnel endpoint identification (multicast/broadcast session tunnel endpoint ID, MB session TEID).

Among other things, the QoS information for the multicast session may include allocation and preemption priority (allocation and retention priority, ARP) information for the multicast transmission, and/or a 5G QoS flow identification (5G QoS Flow ID,5QI).

Wherein the state information of the multicast session may be used to indicate a state of the multicast session, such as an active state or a deactivated state. The region identification of the MBS may be used to identify an MBS Service Area (MBS Service Area).

Wherein, the area identification of the MBS can comprise a cell identification or a tracking area identification.

The identification information of the terminal corresponding to the multicast session may be used to indicate the identification of the terminal corresponding to the multicast session, such as a 5G system architecture evolution-temporary mobile subscription identifier (5G-system architecture evolution-temporary mobile subscriber identity, 5G-S-TMSI), and so on.

5. The terminals in the multicast group are switched to the inactive state, and the flow of receiving multicast data in the inactive state

In this embodiment, the terminal being switched to the inactive state may be replaced by: the terminal is released to the inactive state, or the terminal is configured to the inactive state, etc., and will be described in detail herein.

The following describes a procedure in which a terminal in a multicast group is switched to an inactive state and receives multicast data in the inactive state, taking as an example a context in which the terminal joins the multicast group through the access network device 1 and the access network device 1 successfully establishes a multicast session.

S21: the access network device 1 sends an RRC Release (RRC Release) message to the terminal.

Accordingly, the terminal receives the RRC release message from the access network device 1.

The RRC release message may include one or more of indication (suspend indication) information released to an inactive state, configuration (suspend configuration) information, RNA information, or information such as an inactive radio network temporary identity (inactive radio network temporary identifier, I-RNTI).

Wherein the indication or configuration information released to the inactive state may be used to indicate switching the terminal to the inactive state. RNA information can be used to indicate RNA. The RNA information may also be sent in other messages, without limitation. In this example, the RNA information comprises an identification of the access network device 1 and an identification of the access network device 2.

S22: the access network device 1 sends a second request to access network devices within the RNA other than the access network device 1, in this case the access network device 2.

Accordingly, the access network device (access network device 2 in this example) other than the access network device 1 within the RNA receives the second request from the access network device 1.

Wherein the second request may be used to request to establish a context of a multicast session of the access network device 2 for the multicast group, or the second request may be used to request to establish a transmission channel corresponding to the multicast group, or the second request may be used to request to send multicast data corresponding to the multicast group, or the second request may be used to request to process multicast data corresponding to the multicast group.

It may be appreciated that if the RNA information further includes the identifier of the access network device 3, the access network device 1 further sends a request to the access network device 3 to request to establish a context of the multicast session of the access network device 3 for the multicast group, or to request to establish a transmission channel corresponding to the multicast group, or to request to send multicast data corresponding to the multicast group, or to request to process multicast data corresponding to the multicast group.

S23: if the access network device 2 does not establish the context of the multicast session of the access network device 2, the access network device 2 establishes the context of the multicast session of the access network device 2.

For example, the access network device 2 may interact with the core network, establishing a context for a multicast session of the access network device 2.

After S23, the access network devices within the RNA (access network device 1 and access network device 2 in this example) have established their corresponding multicast session context. Thus, access network devices within the RNA can all transmit multicast data.

It will be appreciated that after S23, the terminal may revert to the connected state under any one of the access network devices within the RNA, such as access network device 1 or access network device 2. At this time, how the access network device within the RNA maintains the context of its corresponding multicast session remains a problem to be solved.

In order to solve the above problems, embodiments of the present application provide a multicast communication method. In the method, the access network device may release the context of the multicast session if the last terminal in the multicast group connected to the access network device leaves the access network device and there is no inactive terminal in the multicast group associated with the access network device. In this way, the terminal in the multicast group can be ensured to receive the multicast data, and the access network device can timely release the context of the multicast session corresponding to the multicast group, so as to save resources. The specific process of the method will be described in the following embodiments shown in fig. 3A, 3B or 4, and will not be described herein.

The method provided by the embodiment of the application can be used for various communication systems. For example, the communication system may be a long term evolution (long term evolution, LTE) system, a fifth generation (5th generation,5G) communication system, a Wi-Fi system, a third generation partnership project (3rd generation partnership project,3GPP) related communication system, a future evolution communication system (e.g., sixth generation (6th generation,6G) communication system, etc.), or a system incorporating multiple systems, without limitation. Wherein 5G may also be referred to as New Radio (NR). The method provided in the embodiment of the present application will be described below by taking the communication system 10 shown in fig. 1 as an example. Fig. 1 is only a schematic diagram, and does not constitute a limitation on the applicable scenario of the technical solution provided in the present application.

As shown in fig. 1, a schematic architecture of a communication system 10 is provided. In fig. 1, communication system 10 may include an access network device 101, an access network device 102, a terminal 103 that may communicate with access network device 101, and a terminal 104 that may communicate with access network device 102. Optionally, the communication system 10 further comprises an access network device 105.

In fig. 1, an access network device may provide wireless access services for a terminal. Specifically, each access network device corresponds to a service coverage area, and a terminal entering the area may communicate with the access network device to receive the radio access service provided by the access network device. Alternatively, the service coverage area may comprise one or more cells. The terminal and the access network equipment can communicate through a Uu port link. Among them, the Uu port link can be divided into an Uplink (UL) and a Downlink (DL) according to the direction of data transmitted thereon. Uplink data sent from the terminal to the access network device can be transmitted on UL, and downlink data transmitted from the access network device to the terminal can be transmitted on DL.

Access network devices, for example: the access network device 101, the access network device 102, or the access network device 105 may be any device having a wireless transceiving function. Including but not limited to: an evolved node B (NodeB or eNB or e-NodeB, evolutional Node B) in LTE, a base station (gNodeB or gNB) or a transceiver point (transmission receiving point/transmission reception point, TRP) in NR, a base station for 3GPP subsequent evolution, an access node in Wi-Fi system, a wireless relay node, a wireless backhaul node, and the like. The base station may be: macro base station, micro base station, pico base station, small station, relay station, or balloon station, etc. Multiple base stations may support networks of the same technology as mentioned above, or may support networks of different technologies as mentioned above. A base station may contain one or more co-sited or non-co-sited TRPs. The access network device may also be a radio controller in the context of a cloud radio access network (cloud radio access network, CRAN). The access network device may also be a Centralized Unit (CU), and/or a Distributed Unit (DU). The access network device may also be a server, a wearable device, a machine communication device, or an in-vehicle device, etc. The following description will take an access network device as a base station as an example. The access network devices may be the same type of base station, or may be different types of base stations. The base station may communicate with the terminal or may communicate with the terminal through a relay station. The terminal may communicate with a plurality of base stations of different technologies, for example, the terminal may communicate with a base station supporting an LTE network, may communicate with a base station supporting a 5G network, and may support dual connectivity with the base station of the LTE network and the base station of the 5G network. In the embodiment of the present application, the means for implementing the function of the access network device may be the access network device; or may be a device, such as a system-on-a-chip, capable of supporting the access network device to perform this function, which may be installed in or used in conjunction with the access network device. In the embodiment of the application, the chip system may be formed by a chip, and may also include a chip and other discrete devices. In the method provided in the embodiment of the present application, taking an example that a device for implementing a function of an access network device is an access network device, the method provided in the embodiment of the present application is described.

A terminal, for example: the terminal 103 or the terminal 104 is a device having a wireless transmitting and receiving function. The terminal can be deployed on land, including indoor or outdoor, hand-held or vehicle-mounted; can also be deployed on the water surface (such as ships, etc.); but may also be deployed in the air (e.g., on aircraft, balloon, satellite, etc.). A terminal may also be referred to as a terminal device, which may be a User Equipment (UE), wherein the UE includes a handheld device, an in-vehicle device, a wearable device, or a computing device with wireless communication capabilities. The UE may be a mobile phone (mobile phone), a tablet computer, or a computer with a wireless transceiver function, for example. The terminal device may also be a Virtual Reality (VR) terminal device, an augmented reality (augmented reality, AR) terminal device, a wireless terminal in industrial control, a wireless terminal in unmanned, a wireless terminal in telemedicine, a wireless terminal in smart grid, a wireless terminal in smart city, or a wireless terminal in smart home (smart home), etc. In the embodiment of the present application, the device for implementing the function of the terminal may be the terminal; or may be a device, such as a chip system, capable of supporting the terminal to perform the function, which may be installed in the terminal or used in cooperation with the terminal. In the method provided in the embodiment of the present application, a device for implementing a function of a terminal is described as an example of the terminal.

By way of example, and not limitation, the terminal may be a wearable device. The wearable device can also be called as a wearable intelligent device, and is a generic name for intelligently designing daily wear by applying wearable technology and developing wearable devices, such as glasses, gloves, watches, clothes, shoes and the like. The wearable device is a portable device that is worn directly on the body or integrated into the clothing or accessories of the user. For example, the wearable device is not just a hardware device, but a device that realizes a powerful function through software support, data interaction and cloud interaction. Generalized wearable smart devices include devices that are fully functional, large in size, and may not rely on smartphones to achieve complete or partial functionality, such as: smart watches or smart glasses, etc., as well as devices that need to be used with other devices, such as smartphones, such as smart bracelets, smart jewelry, etc., that perform physical sign monitoring, focusing only on certain types of application functions.

The terminal can be a terminal in an internet of things (internet of things, ioT) system, the IoT is an important component of future information technology development, and the main technical characteristic of the terminal is that the article is connected with a network through a communication technology, so that an intelligent network for man-machine interconnection and internet of things interconnection is realized. The terminal in the present application may be a terminal in machine type communication (machine type communication, MTC). The terminal of the present application may be an in-vehicle module, an in-vehicle component, an in-vehicle chip, or an in-vehicle unit built in a vehicle as one or more components or units, and the vehicle may implement the method of the present application through the in-vehicle module, the in-vehicle component, the in-vehicle chip, or the in-vehicle unit built in.

Optionally, the communication system shown in fig. 1 further comprises at least one UPF network element in communication with the access network device in fig. 1 and at least one SMF network element (not shown in fig. 1) in communication with the access network device in fig. 1.

The SMF network element is configured to manage a session or establish a session, for example, to establish a multicast session corresponding to a multicast group.

The UPF network element is used for establishing the context of the multicast session corresponding to the multicast group or establishing a transmission channel between the UPF network element and the access network equipment corresponding to the UPF network element for transmitting the multicast data corresponding to the multicast group.

The communication system 10 shown in fig. 1 is for example only and is not intended to limit the scope of the present application. Those skilled in the art will appreciate that in the specific implementation, the communication system 10 may include other devices, and the number of access network devices and terminals may be determined according to specific needs, without limitation.

Alternatively, each network element or device (e.g., access network device, etc.) in fig. 1 may also be referred to as a communication apparatus, which may be a general-purpose device or a special-purpose device, and is not limited specifically.

Optionally, the relevant functions of each network element or device (e.g., access network device, etc.) in fig. 1 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 limited specifically. It will be appreciated that the functions described above may be either network elements in a hardware device, or software functions running on dedicated hardware, or a combination of hardware and software, or virtualized functions instantiated on a platform (e.g., a cloud platform).

In particular implementations, each network element or device (e.g., access network device, etc.) in fig. 1 may employ the constituent structure shown in fig. 2 or include the components shown in fig. 2. Fig. 2 is a schematic diagram of a hardware configuration of a communication device applicable to an embodiment of the present application. The communication device 20 comprises at least one processor 201 and at least one communication interface 204 for implementing the methods provided by the embodiments of the present application. The communication device 20 may also include a communication line 202 and a memory 203.

The processor 201 may be a general purpose central processing unit (central processing unit, CPU), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of programs in accordance with aspects of the present application.

Communication line 202 may include a pathway to transfer information between the aforementioned components, such as a bus.

Communication interface 204 for communicating with other devices or communication networks. The communication interface 204 may be any transceiver-like device such as an ethernet interface, a radio access network (radio access network, RAN) interface, a wireless local area network (wireless local area networks, WLAN) interface, a transceiver, pins, buses, or transceiver circuitry, etc.

The memory 203 may be, but is not limited to, a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (random access memory, RAM) or other type of dynamic storage device that can store information and instructions, or an electrically erasable programmable read-only memory (electrically erasable programmable read-only memory, EEPROM), a compact disc read-only memory (compact disc read-only memory) or other optical disc storage, optical disc storage (including compact disc, laser disc, optical disc, digital versatile disc, blu-ray disc, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. The memory may be self-contained and coupled to the processor 201 via communication line 202. Memory 203 may also be integrated with processor 201. Wherein the memory may generally have non-volatility.

The memory 203 is configured to store computer-executable instructions related to executing the schemes provided in the embodiments of the present application, and is controlled to be executed by the processor 201. The processor 201 is configured to execute computer-executable instructions stored in the memory 203, thereby implementing the methods provided by the embodiments of the present application. Alternatively, the processor 201 performs processing-related functions in the methods provided in the embodiments described below, and the communication interface 204 is responsible for communicating with other devices or communication networks, which are not particularly limited.

The computer-executable instructions may also be referred to as application code, and are not particularly limited.

Where coupling is an indirect coupling or communication connection between devices, units, or modules, which may be in electrical, mechanical, or other form, for information interaction between the devices, units, or modules.

As one example, processor 201 may include one or more CPUs, such as CPU0 and CPU1 in fig. 2.

As one example, the communication device 20 may include a plurality of processors, such as the processor 201 and the processor 207 in fig. 2. Each of these processors may be a single-core (single-CPU) processor or may be a multi-core (multi-CPU) processor. A processor herein may refer to one or more devices, circuits, and/or processing cores for processing data (e.g., computer program instructions).

As an embodiment, the communication apparatus 20 may further comprise an output device 205 and/or an input device 206. The output device 205 is coupled to the processor 201 and can display information in a variety of ways. For example, the output device 205 may be a liquid crystal display (liquid crystal display, LCD), a light emitting diode (light emitting diode, LED) display device, a Cathode Ray Tube (CRT) display device, or a projector (projector), or the like. The input device 206 is coupled to the processor 201 and may receive user input in a variety of ways. For example, the input device 206 may be a mouse, a keyboard, a touch screen device, a sensing device, or the like.

It will be appreciated that the constituent structures shown in fig. 2 do not constitute a limitation of the communication device, and that the communication device may include more or less components than those shown in fig. 2, or may combine certain components, or may be arranged in different components.

Methods provided in embodiments of the present application will be described below with reference to the accompanying drawings. Each network element in the following embodiments may be provided with the components shown in fig. 2, which are not described in detail.

It is to be understood that "transmitting" may be understood as transmitting and/or receiving depending on the particular context. "transfer" may be a noun or a verb. Where the subject of execution of an action is de-emphasized, transmission and/or reception is often replaced by "transmission". For example, the phrase "transmitting multicast data" may be understood as "transmitting multicast data" from the perspective of the transmitting end, and "receiving multicast data" from the perspective of the receiving end.

It should be understood that, in the embodiments described below, the names of the messages between the network elements or the names of the parameters in the messages are only an example, and may be other names in the specific implementation, which is not limited specifically.

Where "/" may indicate that the associated object is an "or" relationship, e.g., A/B may represent A or B; "and/or" may be used to describe that there are three relationships associated with an object, e.g., a and/or B, which may represent: there are three cases, a alone, a and B together, and B alone, wherein a, B may be singular or plural. Furthermore, expressions similar to "at least one of A, B and C" or "at least one of A, B or C" are generally used to denote any one of the following: a alone; b alone; c alone; both A and B are present; both A and C are present; b and C are present simultaneously; a, B and C are both present. The above is an alternative entry for the item exemplified by A, B and C together with three elements, the meaning of which can be obtained according to the rules described above when there are more elements in the expression.

In order to facilitate description of the technical solutions of the embodiments of the present application, the words "first", "second", etc. may be used to distinguish between technical features that are functionally the same or similar. The terms "first," "second," and the like do not necessarily denote any order of quantity or order of execution, nor do the terms "first," "second," and the like. In this application embodiment, the terms "exemplary" or "such as" and the like are used to denote examples, illustrations, or descriptions, and any embodiment or design described as "exemplary" or "such as" should not be construed as preferred or advantageous over other embodiments or designs. The use of the word "exemplary" or "such as" is intended to present the relevant concepts in a concrete fashion to facilitate understanding.

It is appreciated that reference throughout this specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, various embodiments are not necessarily referring to the same embodiments throughout the specification. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It should be understood that, in various embodiments of the present application, the sequence number of each process does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

It is to be understood that in this application, the terms "when …" and "if" are used to indicate that the corresponding process is performed under some objective condition, and are not limited in time, but do not require any judgment in the implementation, and do not mean that there are other limitations.

The term "simultaneously" in the present application is understood to mean at the same point in time, also during a period of time, and also during the same period.

It can be appreciated that some optional features of the embodiments of the present application may be implemented independently in some scenarios, independent of other features, such as the scheme on which they are currently based, to solve corresponding technical problems, achieve corresponding effects, or may be combined with other features according to requirements in some scenarios. Accordingly, the apparatus provided in the embodiments of the present application may also implement these features or functions accordingly, which is not described herein.

It will be appreciated that the same steps or technical features having the same function in the embodiments of the present application may be referred to and referred to by each other in different embodiments.

It will be appreciated that the access network device may perform some or all of the steps in the embodiments of the present application, which are examples only, and may also perform other steps or variations of the various steps. Furthermore, the various steps may be performed in a different order presented in embodiments of the present application, and it is possible that not all of the steps in embodiments of the present application may be performed.

As shown in fig. 3A, a multicast communication method provided in an embodiment of the present application may include the following steps:

s301: the first access network device determines that a last terminal in the multicast group connected to the first access network device leaves the first access network device, and that no inactive terminal associated with the first access network device exists in the multicast group.

S302: the first access network device releases the context of the multicast session.

The multicast session is used for transmitting multicast data corresponding to the multicast group.

Specifically, the release in step S302 may be understood as deletion, not as limitation.

The first access network device in S301 may be any one of the access network devices in the communication system 10 shown in fig. 1, for example, the access network device 101, the access network device 102, or the access network device 105 in fig. 1.

Optionally, before S301, the first access network device establishes a context of the multicast session for the multicast group. The context of the multicast session may be used for transmitting multicast data corresponding to the multicast group between the first access network device and its corresponding UPF network element, or the context of the multicast session may be used for transmitting multicast data between the first access network device and access network devices other than the first access network device.

The context of the multicast session established by the first access network device for the multicast group may be replaced by the context of the multicast session established by the first access network device for the multicast group, or the first access network device establishes a transmission channel of the multicast session corresponding to the multicast group.

It will be appreciated that if a terminal in a multicast group joins the multicast group through different access network devices, then these access network devices will establish the context of the multicast session for the multicast group. In order to distinguish the context of the multicast session established by different access network devices for the multicast group in the embodiment of the present application, the context of the multicast session established by each access network device for the multicast group is referred to as the context of the multicast session of the access network device. For example, if both the access network device 1 and the access network device 2 establish a context of a multicast session for a multicast group, the context of the multicast session established by the access network device 1 for the multicast group is referred to as the context of the multicast session of the access network device 1, and the context of the multicast session established by the access network device 2 for the multicast group is referred to as the context of the multicast session of the access network device 2. Thus, the context of the multicast session established by the first access network device for the multicast group may also be referred to as the context of the multicast session of the first access network device. The description is unified and will not be repeated here.

In an alternative implementation, when the last terminal in the multicast group connected to the first access network device is deleted from the context of the multicast session by the first access network device; or when the last terminal connected with the first access network device in the multicast group is switched to other access network devices (hereinafter referred to as other access network devices) except the first access network device, the first access network determines that the last terminal connected with the first access network device in the multicast group leaves the first access network device.

Illustratively, taking the first access network device as the next generation radio access network (next generation radio access network, NG-RAN), in the handover preparation phase, when the last terminal in the multicast group connected to the first access network device (i.e., the source NG-RAN) is handed over to the target NG-RAN, the first access network determines that the last terminal in the multicast group connected to the first access network device leaves the first access network device. Or, when the last terminal in the multicast group connected to the first access network device (i.e. source NG-RAN) switches to the target evolved universal terrestrial radio access (network) (evolved universal terrestrial radio access, E-UTRAN), the first access network determines that the last terminal in the multicast group connected to the first access network device leaves the first access network device.

It should be noted that, there may be other alternative description manners where there is no inactive terminal associated with the first access network device in the multicast group, for example, it may also be described that there is no intersection between the coverage area of the first access network device and the RNA of any terminal in the multicast group, or it may be described that the coverage area of the first access network device is not included in the RNA of any terminal in the multicast group, or it may be described that the access network device within the RNA of any terminal in the multicast group does not include the first access network device, or it may be described that there is no common cell or tracking area between the coverage area of the first access network device and the RNA of any terminal in the multicast group, or it may be described that the cell or tracking area corresponding to the RNA of any terminal in the multicast group does not belong to the first access network device.

Illustratively, taking the example that the multicast group includes the terminal 1 and the terminal 2, and the cell of the first access network device includes the cell 1 and the cell 2, if the RNA of the terminal 1 includes the cell 3 and the cell 4, and the RNA of the terminal 2 includes the cell 5 and the cell 6, no inactive terminal associated with the first access network device exists in the multicast group. If the RNA of terminal 1 comprises cell 1 and cell 4 and the RNA of terminal 2 comprises cell 5 and cell 6, then there is a terminal in the multicast group in an inactive state associated with the first access network device. If the RNA of the terminal 1 includes the identifier of the first access network device and the identifier of the access network device 2, and the RNA of the terminal 2 includes the identifier of the access network device 2 and the identifier of the access network device 3, then the terminal in the inactive state associated with the first access network device exists in the multicast group. If the RNA of the terminal 1 includes the TA of the access network device 2 and the TA of the access network device 3, and the RNA of the terminal 2 includes the TA of the access network device 2 and the TA of the access network device 4, then there is no terminal in the multicast group in an inactive state associated with the first access network device.

Note that S301 may be replaced with: when the last terminal in the multicast group connected with the first access network device leaves the first access network device, the first access network device determines that no inactive terminal associated with the first access network device exists in the multicast group. Further, the last terminal in the multicast group connected to the first access network device leaving the first access network device may be replaced by: the last terminal in the multicast group connected to the first access network device is deleted from the context of the multicast session by the first access network device; or, the last terminal in the multicast group connected to the first access network device is handed over to other access network devices than the first access network device.

Based on the method shown in fig. 3A, a first access network device releases a context of the multicast session in a case where a last terminal in the multicast group connected to the first access network device leaves the first access network device and there is no inactive terminal associated with the first access network device in the multicast group. In this way, the terminal in the multicast group can be ensured to receive the multicast data, and the access network device can timely release the context of the multicast session corresponding to the multicast group, so as to save resources.

Optionally, in an implementation scenario of the foregoing embodiment, after S301, the foregoing method further includes: the first access network device sends a request message to the first network device.

Accordingly, the first network device receives a request message from the first access network device.

Wherein the request message is for requesting release of the multicast session. The first network device may be an access and mobility management function (access and mobility management function, AMF) network element, MB-SMF network element, UPF network element, or other access network device, without limitation.

In a possible implementation manner, before S302, the method further includes: the first access network device receives a response message from the first network device.

Correspondingly, the first network device sends a response message to the first access network device.

Wherein the response message is used for responding to the request message. The request message may be a multicast session release request and the response message may be a multicast session release response, without limitation.

Based on the method provided in the implementation scenario, the first access network device may determine in S301 that the last terminal in the multicast group connected to the first access network device leaves the first access network device, and if there is no inactive terminal associated with the first access network device in the multicast group, send the request message to the first network device, and release the context of the multicast session after receiving the response message.

Optionally, in another implementation scenario of the foregoing embodiment, the foregoing method further includes: the first access network device sends a multicast session leave message to the second network device. Accordingly, the second network device receives a multicast session leave message from the first access network device.

Wherein the second network device may be a core network device or other access network device. The core network device is an AMF network element, an MB-SMF network element or a UPF network element.

For example, when the context of the multicast session is used for transmitting multicast data corresponding to the multicast group between the first access network device and the UPF network element (the UPF network element may be replaced with an MB-UPF network element, which is not described in detail herein), the second network device may be a core network device. Alternatively, if the context of the multicast session is used for transmitting multicast data between the first access network device and the other access network device (e.g., the context includes an identification of a transmission path between the first access network device and the second access network device), then the second network device is the other access network device.

Wherein the multicast session leave message may be used to request or trigger release of the context of the multicast session corresponding to the multicast group. Alternatively, the multicast session leave message may be used to indicate that the multicast session corresponding to the multicast group left the first access network device. The context of the multicast session corresponding to the released multicast group may be replaced by the context of the multicast session corresponding to the deleted multicast group.

Wherein the multicast session leave message may be replaced with: a transmission channel release request message, e.g., DISTRIBUTION RELEASE REQUEST message. The transmission channel release request message may be used to request release of a transmission channel of a multicast session corresponding to the multicast group. The multicast session leave message may also be replaced with: an IP packet containing leave information, such as an internet group management protocol (internet group management protocol, IGMP) leave (leave) message, or the like.

Based on the method provided by the implementation scenario, the first access network device can trigger the release of the context of the multicast session of the network device, thereby further saving network resources.

It should be noted that the embodiment of the present application further provides a multicast communication method, including: the first access network equipment releases the context of the multicast session established by the first access network equipment for the multicast group only when the last terminal connected with the first access network equipment in the multicast group leaves the first access network equipment; or the first access network device releases the context of the multicast session established by the first access network device for the multicast group only if the terminal in the inactive state associated with the first access network device is not present in the multicast group.

For example, if there is no terminal in the multicast group in the inactive state, when the last terminal in the multicast group connected to the first access network device leaves the first access network device, the first access network device releases the context of the multicast session established by the first access network device for the multicast group. If the terminal in the connection state does not exist in the multicast group, the first access network device releases the context of the multicast session established by the first access network device for the multicast group when the terminal in the non-activation state associated with the first access network device does not exist in the multicast group.

It will be appreciated that the actions of the first access network device in S301-S302 described above may be performed by the processor 201 in the communication apparatus 20 shown in fig. 2 invoking application program code stored in the memory 203, which is not limited in any way by the embodiments of the present application.

Alternatively, in another implementation scenario of the above embodiment, step S301 may include steps S301A and S301B, which are specifically as follows:

S301A: the first access network device determines that the last terminal connected with the first access network device in the multicast group leaves the first access network device according to the first information of the terminal in the connection state associated with the first access network device in the multicast group.

The first information may be any one of the following 4 cases: case a: the first information may be used to indicate the number of terminals in the multicast group that are connected to the first access network device and in a connected state, or, in case B: the first information may be used to indicate the number of contexts of the terminals in the multicast group stored in the first access network device, or case C: the first information may be used to indicate whether the context of the terminal in the multicast group is stored in the first access network device or, alternatively, case D: the first information is used to indicate a terminal of a connection state associated with an identification of the multicast group.

Optionally, the first information includes a multicast/broadcast service (MBS) -related context corresponding to the multicast group stored in the first access network device.

For example, the first access network device stores therein MBS-related contexts. The MBS-related context includes first information corresponding to the multicast session 1, first information … corresponding to the multicast session 2, and first information corresponding to the multicast session m. The multicast session 1 to the multicast session m are multicast sessions corresponding to different multicast groups, and are used for transmitting multicast data of the multicast groups corresponding to the multicast session 1 to the multicast session m.

Case a, case B, case C, and case D are described below, respectively.

Case a: the first information may be used to indicate a number of terminals in the multicast group that are connected to the first access network device and in a connected state.

One possible design, the first information includes a numerical value. The value is an initial value, for example, 0, or may be another number or value (for example, FF,00, -1, or 1, etc.), and is not limited. When the number of terminals in the multicast group, which are connected to the first access network device and are in a connected state, increases, the value also increases, for example, when the number of terminals increases by 1, the value also increases by 1; when the number of terminals in the multicast group connected to the first access network device is reduced, the value is also reduced, for example, when the number of terminals is reduced by 1, the value is also reduced by 1.

In another possible design, the first information is state information, i.e. the first information may correspond to a plurality of states. Initially, the state corresponding to the first information is an initial state. When the number of terminals in a connected state increases, for example, when the number of terminals increases by 1, the state corresponding to the first information changes from the current state to the next state of the current state; when the number of terminals in the multicast group connected to the first access network device decreases, the first access network device updates the first information, for example, when the number of terminals decreases by 1, the state corresponding to the first information changes from the current state to the state previous to the current state.

It may be understood that, when the value included in the first information is an initial value or the state corresponding to the first information is an initial state, the number of terminals in the multicast group, which are connected to the first access network device and are in a connected state, is 0 or 1, which is not limited.

It will be appreciated that when the first access network device is connected to the multicast group and the number of terminals in a connected state is 0, the first access network device may determine that the last terminal in the multicast group connected to the first access network device leaves the first access network device.

In one possible implementation, the first access network device updates the first information when a terminal in the multicast group enters a connected state under the first access network device.

For example, after a terminal joins a multicast group through a first access network device, the first access network device increases the number indicated by the first information by 1; or after the first access network device receives the RRC connection recovery request from the terminal in the multicast group, the first access network device adds 1 to the number indicated by the first information; alternatively, after the first access network device receives the context of one terminal in the multicast group from the other access network device, the first access network device adds 1 to the number indicated by the first information.

One possible implementation manner, when a terminal in a multicast group leaves a connection state (such as entering an inactive state or an idle state) under a first access network device, the first access network device updates first information; alternatively, the first access network device updates the first information when a terminal in the multicast group leaves the connected state (e.g., enters an inactive state or an idle state) under the first access network device and enters the connected state under other access network devices.

For example, in case the first access network device determines to release the connection of one terminal in the multicast group, the first access network device decreases the number of first information indications by 1, e.g. after (or before) the first access network device sends an RRC connection release message to the terminal.

For another example, when the first access network device determines that one terminal in the multicast group is switched to the inactive state or the idle state, and enters the connected state under the condition that other access network devices, for example, after the first access network device receives information from the other access network devices requesting the context of the terminal, or after the first access network device sends the information of the context of the terminal to the other access network devices, or after the first access network device receives information from the other access network devices indicating that the terminal enters the connected state under the other access network devices, the first access network device subtracts 1 from the number indicated by the first information.

Case B: the first information may be used to indicate a number of contexts of the terminals in the multicast group stored in the first access network device.

One possible design, the first information includes a numerical value. The value is an initial value, for example, 0, or may be another number or value (for example, FF,00, -1, or 1, etc.), and is not limited. When the number of contexts of a terminal in the multicast group stored in the first access network device increases, the value also increases, for example, when the number of contexts of the terminal increases by 1, the value also increases by 1; when the number of contexts of a terminal in the multicast group stored in the first access network device is reduced, the value is also reduced, for example, when the number of contexts of the terminal is reduced by 1, the value is also reduced by 1.

In another possible design, the first information is state information, i.e. the first information may correspond to a plurality of states. Initially, the state corresponding to the first information is an initial state. When the number of contexts of the terminal in the multicast group stored in the first access network device increases, the first access network device updates the first information, for example, when the number of contexts of the terminal increases by 1, the state to which the first information corresponds changes from the current state to the next state of the current state; when the number of contexts of a terminal in a multicast group stored in the first access network device decreases, the first access network device updates the first information, for example, when the number of contexts of the terminal decreases by 1, the state to which the first information corresponds changes from the current state to the state previous to the current state.

It may be understood that, when the value included in the first information is an initial value or the state corresponding to the first information is an initial state, the number of contexts of the terminal in the multicast group stored in the first access network device may be indicated as 0 or 1, which is not limited.

It will be appreciated that when the number of contexts of the terminals in the multicast group stored in the first access network device is 0, the first access network device may determine that the last terminal in the multicast group connected to the first access network device leaves the first access network device.

One possible implementation manner, after the first access network device receives the context of the terminal in the multicast group that is not stored in the first access network device, the first access network device updates the first information; alternatively, the first access network device updates the first information each time the first access network device receives a context of a terminal in the multicast group.

For example, the first access network device increases the number of first information indications by 1 after receiving a context of one terminal in the multicast group not stored in the first access network device.

One possible implementation manner, when the first access network device receives information of the context of the terminal in the multicast group from other access network devices, or when the first access network device sends the information of the context of the terminal in the multicast group to other access network devices, or when the first access network device deletes the context of the terminal in the multicast group, the first access network device updates the first information. For example, the first access network device decreases the number of first information indications by 1 after sending information of the context of one terminal in the multicast group to other access network devices.

Case C: the first information may be used to indicate whether a context of a terminal in the multicast group is stored in the first access network device.

One possible implementation manner may search for whether the identifier of the multicast group is stored in the context of the stored terminal, if the identifier of the multicast group is stored, the first access network device indicates that the context of the terminal in the multicast group is stored in the first access network device, and if the identifier of the multicast group is not stored, the first access network device indicates that the context of the terminal in the multicast group is not stored in the first access network device.

It will be appreciated that if the context of the terminal in the multicast group is not stored in the first access network device, it may be determined that the last terminal in the multicast group connected to the first access network device leaves the first access network device.

Case D: the first information is used for indicating a terminal of a connection state associated with an identification of the multicast group, namely: the first information may be used to indicate terminals in a connected state in the multicast group.

One possible design, the first information includes an identification of a terminal associated with an identification of the multicast group, e.g., an identification of a terminal of a corresponding connection state of the multicast group (e.g., 5G-S-TMSI). Initially, the first information is empty, i.e. does not include the identity of the terminal with which the identity of the multicast group is associated. It will be appreciated that the present application is not limited to the form of the first information, for example, the first information may include a list as shown in table 0 (other forms of lists are possible), or the first information may include key-value pairs, without limitation.

TABLE 0

Identification of multicast groups	Identification of terminals associated with identification of multicast groups
		TMGI 1	An identification of the terminal 1,Identification of terminal 2 and identification of terminal 3
TMGI 2	Identification of terminal 2 and identification of terminal 4
		TMGI 3	Identification of terminal 3, identification of terminal 5 and identification of terminal 6

In table 0, the terminals associated with TMGI 1 include terminal 1, terminal 2, and terminal 3. The terminals associated with TMGI 2 include terminal 2 and terminal 4. The terminals associated with TMGI 3 include terminal 3, terminal 5, and terminal 6.

For example, after a terminal joins a multicast group through a first access network device, the first access network device adds an identifier of the terminal to first information; or after the first access network equipment receives the RRC connection recovery request from the terminal in the multicast group, the first access network equipment adds the identifier of the terminal into the first information; or after the first access network device receives the context of one terminal in the multicast group from other access network devices, the first access network device adds the identifier of the terminal to the first information.

For example, in case the first access network device determines to release the connection of one terminal in the multicast group, the first access network device deletes the identity of the terminal from the first information, e.g. after (or before) the first access network device sends an RRC connection release message to the terminal.

For another example, when the first access network device determines that one terminal in the multicast group is switched to the inactive state or the idle state, and enters the connected state under the condition that other access network devices, for example, after the first access network device receives information from the other access network devices requesting the context of the terminal, or after the first access network device sends the information of the context of the terminal to the other access network devices, or after the first access network device receives information from the other access network devices indicating that the terminal enters the connected state under the other access network devices, the first access network device deletes the identifier of the terminal from the first information.

S301B: the first access network device determines that the terminal in the inactive state associated with the first access network device does not exist in the multicast group according to the second information of the terminal in the inactive state associated with the first access network device in the multicast group.

In this embodiment of the present application, a terminal in an inactive state associated with a first access network device in a multicast group includes: a terminal switched to an inactive state by a first access network device in a multicast group; and a terminal in the multicast group switched to an inactive state by the other access network device, and the RNA of the terminal includes all or part of the coverage area of the first access network device.

In the following, the multicast group includes a terminal 1, a terminal 2 and a terminal 3, where both the terminal 1 and the terminal 2 establish an RRC connection with a first access network device, and the terminal 3 establishes an RRC connection with the access network device 2, and a cell of the first access network device includes a cell 1 and a cell 2, and a cell of the access network device 2 includes a cell 3 and a cell 4, which are described as an example.

For example, if the first access network device switches the terminal 1 to the inactive state, the terminal 1 is the inactive state terminal associated with the first access network device in the multicast group.

For another example, if the access network device 2 switches the terminal 3 to the inactive state and the RNA of the terminal 3 includes the cell 1 and the cell 3, the terminal 3 is a terminal in the inactive state associated with the first access network device in the multicast group.

For another example, if the access network device 2 switches the terminal 3 to the inactive state and the RNA of the terminal 3 includes cell 3, cell 4 and cell 5, the terminal 3 is not a terminal in the inactive state associated with the first access network device in the multicast group.

Optionally, the second information is included in an MBS-related context corresponding to the multicast group stored in the first access network device.

In one possible implementation, the second information may be any one of the following three cases: case 1, the second information may be used to indicate a number of inactive terminals associated with the first access network device in the multicast group; or, in case 2, the second information is used to indicate the number of uses of the context of the multicast session (or the transmission channel of the multicast session); alternatively, in case 3, the second information is used to indicate the access network device with which the identity of the multicast group is associated. Case 1, case 2, and case 3 are described below, respectively.

Case 1: the second information may be used to indicate a number of inactive terminals associated with the first access network device in the multicast group.

One possible design, the second information includes a numerical value. The value is an initial value, for example, 0, or may be another number or value (for example, FF,00, -1, or 1, etc.), and is not limited. When the number of inactive terminals associated with the first access network device in the multicast group increases, the value also increases, for example, when the number of terminals increases by 1, the value also increases by 1; when the number of inactive terminals associated with the first access network device in the multicast group is reduced, the value is also reduced, for example when the number of terminals is reduced by 1, the value is also reduced by 1.

In another possible design, the second information is state information, i.e. the second information may correspond to a plurality of states. Initially, the state corresponding to the second information is an initial state. When the number of inactive state terminals associated with the first access network device in the multicast group increases, the first access network device updates the second information, for example, when the number of terminals increases by 1, the state to which the second information corresponds changes from the current state to the next state of the current state; when the number of inactive state terminals associated with the first access network device in the multicast group decreases, the first access network device updates the second information, for example, when the number of terminals decreases by 1, the state to which the second information corresponds changes from the current state to the state immediately preceding the current state.

It may be appreciated that, when the value included in the second information is an initial value or the state corresponding to the second information is an initial state, the number of inactive terminals associated with the first access network device in the multicast group may be indicated as 0 or 1, which is not limited.

It will be appreciated that when the number of inactive terminals associated with the first access network device in the multicast group is 0, the first access network device may determine that there are no inactive terminals associated with the first access network device in the multicast group. That is, when the number of terminals indicated by the second information is zero, the first access network device determines that there are no inactive terminals associated with the first access network device in the multicast group.

In one possible implementation, the first access network device receives first notification information from the second access network device, and updates the second information according to the first notification information. The first notification information may be used to notify that one terminal in the multicast group is switched to the inactive state, or the first notification information is used to notify the number of terminals in the multicast group that are switched to the inactive state by the second access network device, or the first notification information is used to notify that one terminal in the multicast group is switched to the inactive state by the second access network device.

It may be appreciated that the second access network device sends the first notification information to the first access network device in case the terminal in the multicast group switches to the inactive state and the access network device within the RNA of the terminal comprises the first access network device. Accordingly, after the first access network device receives the first notification information, it may be determined that the terminal in the multicast group is switched to the inactive state under the second access network device, and the RNA of the terminal includes all or a part of the coverage area of the first access network device. At this time, the first access network device updates the second information.

Optionally, in order to reduce signaling overhead, the second access network device switches to an inactive state in the terminal in the multicast group, and the access network device in the RNA of the terminal includes the first access network device, and the second access network device sends the first notification information to the first access network device when the first notification information has not been sent before.

It will be appreciated that if the first notification information is used to notify that one terminal in the multicast group switches to the inactive state, the first access network device adds 1 to the number indicated by the second information. Or if the first notification information is used for notifying that the number of the terminals switched to the inactive state by the second access network device in the multicast group is n, the first access network device adds n to the number indicated by the second information.

Optionally, the first notification information is included in a message requesting to establish a context of the multicast session, or in a message requesting to establish a transmission channel for transmitting the multicast data, or in an MBS session transmission request.

In one possible implementation, the first access network device receives second notification information from the second access network device, and updates the second information according to the second notification information. Wherein the second notification information may be used to notify that one terminal in the multicast group leaves the inactive state (e.g., enters a connected state, or enters an idle state), or the second notification information may be used to notify the number of terminals in the multicast group that leave the inactive state under the second access network device. In the case that the second notification information may be used to notify that one terminal in the multicast group leaves the inactive state, the terminal may leave the inactive state at the second access network device, or may leave the inactive state at other access network devices. The terminal may change from an inactive state to a connected state or from an inactive state to an idle state, which is not limited herein.

It will be appreciated that the second access network device sends the second notification information to the first access network device in case the terminal in the multicast group leaves the inactive state and the access network device within the RNA of the terminal comprises the first access network device when in the inactive state.

Optionally, in order to reduce signaling overhead, the second access network device sends the second notification information to the first access network device when the terminal in the multicast group leaves the inactive state, and the access network device in the RNA of any terminal in the multicast group that is switched to the inactive state by the second access network device and is currently in the inactive state does not include the first access network device.

It may be understood that the second access network device receives seventh notification information from the fourth access network device, where the seventh notification information is used to notify that, in the multicast group, the terminal switched to the inactive state by the second access network device is restored to the connected state by the fourth access network device, or the seventh notification information is used to notify that, in a case where the second access network device sends a context of the terminal to the fourth access network device, the second access network device sends second notification information to the first access network device. At this time, the second notification information is used to notify one terminal in the multicast group to leave the inactive state. It will be appreciated that the terminal is left inactive under the fourth access network device.

It will be appreciated that if the second notification information is used to notify a terminal in the multicast group that it is away from the inactive state, the first access network device decreases the number indicated by the second information by 1. Or if the second notification information is used for notifying that the number of the terminals leaving the inactive state at the second access network device in the multicast group is n, the first access network device adds n to the number indicated by the second information.

Optionally, the second notification information is included in a message requesting release of a context of the multicast session, or in a message requesting release of a transmission channel for transmitting the multicast data, or in an MBS session update request message.

Case 2: the second information is used to indicate the number of uses of the context of the multicast session (or the transmission channel of the multicast session).

One possible design, the second information includes a numerical value. The value is an initial value, for example, 0, or may be another number or value (for example, FF,00, -1, or 1, etc.), and is not limited. When the number of times of use of the context of the multicast session (or the transmission channel of the multicast session) increases, the value also increases; as the number of uses of the context of the multicast session (or the transmission channel of the multicast session) decreases, the value also decreases.

In another possible design, the second information is state information, i.e. the second information may correspond to a plurality of states. Initially, the state corresponding to the second information is an initial state. When the number of times of use of the context of the multicast session (or the transmission channel of the multicast session) increases, the first access network device updates the second information, for example, when the number of times of use increases by 1, the state to which the second information corresponds changes from the current state to the next state of the current state; when the number of times of use of the context of the multicast session (or the transmission channel of the multicast session) decreases, the first access network device updates the second information, for example, when the number of times of use decreases by 1, the state to which the second information corresponds changes from the current state to the state immediately preceding the current state.

It can be understood that, when the value included in the second information is an initial value or the state corresponding to the second information is an initial state, the number of times of use of the context of the multicast session (or the transmission channel of the multicast session) may be 0 or 1, which is not limited.

It will be appreciated that when the context of the second multicast session (or the transmission path of the multicast session) is not being used, the first access network device may determine that there are no inactive terminals in the multicast group associated with the first access network device. That is, when the number of times indicated by the second information is zero, the first access network device determines that there is no terminal in the multicast group in an inactive state associated with the first access network device.

In the embodiment of the present application, the number of times the context of the multicast session (or the transmission channel of the multicast session) is used may be understood as the number of times the context of the multicast session (or the transmission channel of the multicast session) is established. For example, if the other access network device requests the first access network device to establish the context of the multicast session corresponding to the multicast group (or the transmission channel of the multicast session corresponding to the multicast group), the number of times indicated by the second information increases, and if the other access network device requests the first access network device to release the context of the multicast session corresponding to the multicast group (or the transmission channel of the multicast session corresponding to the multicast group), the number of times indicated by the second information decreases.

For example, if the number of times indicated by the second information is currently 1, the access network device 2 requests the first access network device to establish the context of the multicast session corresponding to the multicast group, and the number of times indicated by the second information is increased by 1 to become 2. Then, the access network device 3 requests the first access network device to release the context of the multicast session corresponding to the multicast group, and the number of times indicated by the second information is reduced by 1, and becomes 1.

In one possible implementation, the first access network device receives first notification information from the second access network device, and updates the second information according to the first notification information. The first notification information may be used to notify that one terminal in the multicast group is switched to the inactive state, or the first notification information may be used to notify the number of terminals in the multicast group that are switched to the inactive state by the second access network device. This procedure is similar to that in case 1, and reference is made to the corresponding description in case 1. The difference is that the second information indicates the number of uses of the context of the multicast session (or the transmission channel of the multicast session) in case 2.

In one possible implementation, the first access network device receives second notification information from the second access network device, and updates the second information according to the second notification information. Wherein the second notification information may be used to notify that one terminal in the multicast group leaves the inactive state, or the second notification information may be used to notify the number of terminals in the multicast group that leave the inactive state under the second access network device. This procedure is similar to that in case 1, and reference is made to the corresponding description in case 1. The difference is that the second information indicates the number of uses of the context of the multicast session (or the transmission channel of the multicast session) in case 2.

Case 3: the second information is used to indicate the access network device with which the identity of the multicast group is associated.

In the embodiment of the application, the access network device associated with the identifier of the multicast group includes the access network device for switching the terminal in the multicast group to the inactive state, and the access network device in the RNA of the terminal in the inactive state in the multicast group.

One possible design, the second information includes an identification of the access network device with which the identification of the multicast group is associated. Initially, the second information is empty, i.e.: the second information does not include an identification of the access network device with which the identification of the multicast group is associated. It will be appreciated that the present application is not limited to the form of the second information, for example, the second information may include a list as shown in table 1 (other forms of lists are possible), or the second information may include key-value pairs, without limitation.

TABLE 1

Identification of multicast groups	Identification of access network devices associated with identification of multicast groups
		TMGI 1	Identification of access network device 1, identification of access network device 2 and identification of access network device 3
TMGI 2	Identification of access network device 2 and identification of access network device 4
		TMGI 3	Identification of access network device 3, identification of access network device 5 and identification of access network device 6

In table 1, the access network devices associated with TMGI 1 include access network device 1, access network device 2, and access network device 3. The access network device associated with TMGI 2 includes access network device 2 and access network device 4. The access network devices associated with the TMGI 3 include an access network device 3, an access network device 5, and an access network device 6.

In one possible implementation, the first access network device receives first notification information from the second access network device, and updates the second information according to the first notification information. The first notification information may be used to notify that a terminal switched to an inactive state by the second access network device exists in the multicast group.

It may be appreciated that the second access network device sends the first notification information to the first access network device in case the terminal in the multicast group switches to the inactive state and the access network device within the RNA of the terminal comprises the first access network device. Accordingly, after the first access network device receives the first notification information, it may be determined that the terminal in the multicast group is switched to the inactive state under the second access network device, and the RNA of the terminal includes all or a part of the coverage area of the first access network device. At this time, the first access network device updates the second information. For example, the identification of the first access network device and the identification of the second access network device are added to the second information.

In one possible implementation, the first access network device receives second notification information from the second access network device, and updates the second information according to the second notification information. Wherein the second notification information may be used to notify that there is no terminal in the multicast group that is switched to the inactive state by the second access network device.

It will be appreciated that the second access network device sends the second notification information to the first access network device in the case where there is no terminal in the multicast group that is switched to the inactive state by the second access network device, and the access network device within the RNA of the terminal when in the inactive state comprises the first access network device. Or the second access network device sends the second notification information to the first access network device under the condition that the terminal switched to the inactive state by the second access network device in the multicast group leaves the inactive state, the terminal released to the inactive state by the second access network device in the multicast group, and the access network device in the RNA of any terminal which is still in the inactive state does not comprise the first access network device. Correspondingly, after the first access network device receives the second notification information, it may be determined that the terminal in the multicast group is switched from the second access network device to the inactive state. At this time, the first access network device updates the second information. For example, the identification of the first access network device is deleted from the second information.

It may be appreciated that if the first access network device is not included in the access network device associated with the identification of the multicast group, the first access network device determines that there is no inactive terminal associated with the first access network device in the multicast group.

The embodiment of the present application does not limit the execution sequence of S301A and S301B, for example, S301A may be executed first and then S301B may be executed, S301B may be executed first and then S301A may be executed, and S301A and S301B may be executed simultaneously.

It will be appreciated that the actions of the first access network device in S301A-S301B described above may be performed by the processor 201 in the communication apparatus 20 shown in fig. 2 invoking application program code stored in the memory 203, which is not limited in any way by the embodiments of the present application.

It is understood that any of the notification information mentioned in the embodiments of the present application (for example, the first notification information, the second notification information, the third notification information, or the like) may be replaced with the update information, for example, the first notification information may be replaced with the first update information.

Optionally, as shown in fig. 3B, in still another implementation scenario of the foregoing embodiment, if the first access network device determines that the terminal in the multicast group is switched to the inactive state, the method further includes one or more steps of the following S300a-S300d, specifically as follows:

s300a: the first access network device sends third notification information to at least one access network device.

Accordingly, at least one access network device receives third notification information from the first access network device.

It can be appreciated that if the first terminal in the multicast group switches to the inactive state, the first access network device sends third notification information to the at least one access network device.

A possible implementation manner, the third notification information is used to notify a terminal in the multicast group to switch to the inactive state. In this case, the one terminal may or may not be switched to the inactive state by the first access network device. All or part of the difference in coverage area of at least one access network device is included in the RNA of the one terminal.

In another possible implementation manner, the third notification information is used to notify that there is a terminal in the multicast group that is switched to the inactive state by the first access network device. In this case the terminal is switched to the inactive state by the first access network device. All or part of the difference in coverage area of at least one access network device is included in the RNA of the terminal.

For example, the first access network device switches the first terminal in the multicast group to an inactive state and sends third notification information to the access network device within the RNA of the first terminal.

Optionally, in order to reduce signaling overhead, in a case that the first access network device does not send the third notification information to the at least one access network device, the first access network device sends the third notification information to the at least one access network device.

The second access network device may or may not be included in at least one access network device, and is not limited.

Optionally, the third communication information is included in a message requesting to establish a context of the multicast session, or in a message requesting to establish a transmission channel for transmitting the multicast data, or in an MBS session transmission request.

It will be appreciated that the at least one access network device may update the second information maintained by the at least one access network device after receiving the third notification information. The process of updating the second information by at least one access network device is similar to the process of updating the second information by the first access network device, and will not be described again.

Optionally, if the first terminal is recovered from the inactive state to the connected state under the first access network device, or the first terminal leaves the inactive state under the first access network device, for example, the first access network device receives an RRC connection recovery request from the first terminal, the method shown in fig. 3B further includes the following steps:

S300b: the first access network device sends fourth known information to at least one access network device.

Correspondingly, at least one access network device receives fourth notification information from the first access network device.

Wherein the fourth notification information may be used to notify a terminal in the multicast group to leave the inactive state.

In a possible implementation manner, in a case that all or part of the coverage area of at least one access network device is not included in the RNA of any terminal that is switched to the inactive state by the first access network device in the multicast group and is still currently in the inactive state, the first access network device sends fourth notification information to the at least one access network device.

Optionally, the fourth notification information is included in a message requesting release of a context of the multicast session or in a message requesting release of a transmission channel for transmitting the multicast data.

It may be appreciated that, after the at least one access network device receives the fourth notification information, the second information maintained by the at least one access network device may be updated. The process of updating the second information by at least one access network device is similar to the process of updating the second information by the first access network device, and will not be described again.

Optionally, if the first terminal leaves the active state from the third access network device, the method shown in fig. 3B further includes the following steps:

s300c: the first access network device sends fifth notification information to access network devices except the third access network device in the at least one access network device.

Accordingly, the access network device except the third access network device in the at least one access network device receives the fifth notification information from the first access network device.

Wherein the fifth notification information may be used to notify a terminal in the multicast group to leave the inactive state.

In one possible implementation manner, after receiving a message from the third access network device for requesting the context of the first terminal, the first access network device sends fifth notification information to access network devices except the third access network device in the at least one access network device.

Optionally, in order to reduce signaling overhead, after receiving a message from the third access network device for requesting the context of the first terminal, the first access network device is switched to an inactive state by the first access network device in the multicast group, and if the RNA of each terminal that is still in the inactive state currently does not include a coverage area of an access network device other than the third access network device in the at least one access network device, fifth notification information is sent to the access network devices other than the third access network device in the at least one access network device.

Optionally, the fifth notification information is included in a message requesting release of a context of the multicast session or in a message requesting release of a transmission channel for transmitting the multicast data.

It may be appreciated that after the access network device other than the third access network device in the at least one access network device receives the fifth notification information, the second information maintained by the access network device other than the third access network device in the at least one access network device may be updated. The process of updating the second information by the access network devices except the third access network device in the at least one access network device is similar to the process of updating the second information by the first access network device, and will not be repeated.

Optionally, if the last terminal in the terminals switched to the inactive state by the first access network device in the multicast group leaves the inactive state, the method shown in fig. 3B further includes the following steps:

s300d: the first access network device sends sixth notification information to the at least one access network device. Accordingly, the at least one access network device receives the sixth notification information from the first access network device.

The sixth notification information may be used to notify that the number of terminals in the multicast group that are switched to the inactive state by the first access network device is 0, or the sixth notification information may be used to notify that there are no terminals in the multicast group that are switched to the inactive state by the first access network device.

Optionally, the sixth notification information is included in a message requesting release of a context of the multicast session or in a message requesting release of a transmission channel for transmitting the multicast data.

It may be appreciated that the second information maintained by the at least one access network device may be updated after the at least one access network device receives the sixth notification information. The process of updating the second information by at least one access network device is similar to the process of updating the second information by the first access network device, and will not be described again.

It will be appreciated that the actions of any of the access network devices S300a-S300d described above may be performed by the processor 201 in the communication apparatus 20 shown in fig. 2 invoking application program code stored in the memory 203, which is not limited in any way by the embodiments of the present application.

In order to facilitate an understanding of the method provided by the embodiments of the present application, the method provided by the embodiments of the present application is described below in conjunction with the communication system 10 shown in fig. 1. It should be understood that the description of the features, the description of the steps, etc. in the method shown in fig. 3A and 3B are applicable to the method shown in fig. 4 below. Also, the description of the features and the description of the steps in the method shown in fig. 4 are applicable to the methods shown in fig. 3A and 3B, and are not limited thereto.

As shown in fig. 4, another multicast communication method provided in an embodiment of the present application may include the following steps:

s401: terminal 103 joins the multicast group through access network device 101.

For example, the terminal 103 joins the multicast group through the flow shown in the above-described S11 to S13.

Optionally, after S401, for the above case a (the first information may be used to indicate the number of terminals in the multicast group that are connected to the access network device 101 and in a connected state), the access network device 101 increases the number indicated by the first information in the access network device 101 by 1. For the above case B (the first information may be used to indicate the number of contexts of the terminals in the multicast group stored in the access network device 101), the access network device 101 adds 1 to the number indicated by the first information in the access network device 101. For the above case C (the first information may be used to indicate whether the context of the terminal in the multicast group is stored in the access network device 101), the access network device 101 may query the context of the terminal 103 in the multicast group stored in itself, the first information indicating the context of the terminal in the multicast group stored in the access network device 101. For the above case D (the first information is used to indicate the terminal of the connection state with which the identity of the multicast group is associated), the access network device 101 adds the identity of the terminal 103 to the first information.

S402: the access network device 101 sends an RRC connection release message to the terminal 103. Accordingly, the terminal 103 receives the RRC connection release message from the access network device.

For example, the access network device 101 determines that the terminal 103 enters the inactive state according to the auxiliary information provided by the core network, and then sends an RRC connection release message to the terminal 103. Wherein the auxiliary information may include at least one of: the registration area (registration area, RA) of the terminal 103, the discontinuous reception (discontinuous reception, DRX) parameters of the terminal 103, the extended idle state DRX parameters of the terminal 103 (extended idle mode DRX values) or the periodic update timer (Periodic Registration Update timer).

In one possible implementation, the RRC connection release message may include the I-RNTI of the terminal 103 and the RNA information of the terminal 103. In the method shown in fig. 4, the RNA information comprises an identification of a cell of the access network device 102 and an identification of a cell of the access network device 105, i.e.: the RNA of the terminal 103 includes a cell of the access network device 102 and a cell of the access network device 105.

It is understood that S402 may also be performed after S403.

Optionally, after S402, for the above case a, the access network device 101 subtracts 1 from the number indicated by the first information in the access network device 101. For the case B described above, the access network device 101 does not modify the first information. For the above case C, the access network device 101 may query for the context of the terminal 103 itself stored in the multicast group. For the case D described above, the access network device 101 deletes the identity of the terminal 103 from the first information.

S403: the access network device 101 sends first notification information to the access network device 102 and the access network device 105.

Accordingly, the access network device 102 and the access network device 105 receive the first notification information from the access network device 101.

It will be appreciated that, in addition to the introduction of the first notification information in the method shown in fig. 3B, the first notification information may optionally further include at least one of: an identification of the multicast group (e.g., TMGI), region information, I-RNTI of terminal 103, or context of terminal 103. Wherein the context of the terminal 103 may include information of the PDU session of the terminal 103. The information of the PDU session of the terminal 103 may include a PDU session identification of the terminal 103, qoS information (e.g., 5qi, arp, etc.) of the PDU session of the terminal 103.

One possible design, if the terminal 103 joins a multicast group, the first notification information may include an identification of the multicast group; if the terminal 103 joins a plurality of multicast groups, the first notification information may include an identification of the plurality of multicast groups.

One possible design, the area information is used to indicate the RNA of the terminal 103, or to indicate the area of the access network device 102 comprised in the RNA of the terminal 103, or to indicate the area of the access network device 105 comprised in the RNA of the terminal 103.

For example, the area information included in the first notification information sent to the access network device 102 includes RNA information or includes an identification of a cell of the access network device 102 included in the RNA of the terminal 103. The area information included in the first notification information sent to the access network device 105 includes RNA information or includes an identification of a cell of the access network device 105 included in the RNA of the terminal 103.

It will be appreciated that the first notification information may trigger the access network device 102 or the access network device 105 to establish a context of the multicast session for the multicast group. If the access network device 102 does not establish the context of the multicast session for the multicast group, i.e., the access network device 102 does not establish the context of the multicast session of the access network device 102, the access network device 102 establishes the context of the multicast session of the access network device 102. Similarly, if the access network device 105 does not establish the context of the multicast session for the multicast group, i.e., the access network device 105 does not establish the context of the multicast session for the access network device 105, the access network device 105 establishes the context of the multicast session for the access network device 105.

In a possible implementation, if the access network device 101 does not trigger the access network device 102 to establish a context of the multicast session of the access network device 102, the access network device 101 sends the first notification information to the access network device 102. Similarly, if the access network device 101 does not trigger the access network device 105 to establish a context of the multicast session of the access network device 105, the access network device 101 sends the first notification information to the access network device 105.

Optionally, after S402 or S403, the access network device 101 updates the second information in the access network device 101.

For example, for case 1 above (the second information may be used to indicate the number of inactive terminals associated with the first access network device in the multicast group), the access network device 101 adds 1 to the number indicated by the second information. For case 2 (the second information is used to indicate the number of uses of the context of the multicast session (or the transmission channel of the multicast session)), the access network device 101 adds 1 to the number indicated by the second information. For case 3 (the second information is used to indicate the access network device with which the identity of the multicast group is associated), the access network device 101 adds its identity to the second information.

Optionally, after S403, the terminal 103 may receive multicast data corresponding to the multicast group in RNA of the terminal 103.

S404: the access network device 102 updates the second information in the access network device 102 based on the first notification information, and the access network device 105 updates the second information in the access network device 105 based on the first notification information.

In the following description, taking the access network device 102 to update the second information according to the first notification information as an example, a process of updating the second information by the access network device 105 according to the first notification information is similar to a process of updating the second information by the access network device 102 according to the first notification information, which is not described in detail.

As an example, if the access network device 102 does not establish the context of the multicast session of the access network device 102, for case 1, the access network device 102 sets the second information to an initial value or initial state, or the access network device 102 sets the second information to an initial value or initial state, and adds 1 to the number of terminals indicated by the second information. For case 2, the access network device 102 sets the second information to an initial value or initial state, or the access network device 102 sets the second information to an initial value or initial state and increases the number of times indicated by the second information by 1. For case 3, the access network device 102 adds the identity of the access network device 102 to the second information.

As another example, if the access network device 102 establishes a context of the multicast session of the access network device 102, for case 1, the access network device 102 adds 1 to the number of terminals indicated by the second information. For case 2, the access network device 102 increments the number of times indicated by the second information by 1. For case 3, the access network device 102 may determine whether the access network device associated with the multicast group includes an identifier of the access network device 102, if not, the access network device 102 adds its identifier to the second information, and if so, the access network device 102 may not operate; alternatively, the access network device 102 directly adds its identity to the second information.

Optionally, the access network device 102 and/or the access network device 105 sends a response message to the access network device 101 to indicate to the access network device 101 whether the establishment of the context of the multicast session was successful.

Optionally, if the context of the multicast session fails to be established, the response message may include an identifier of the multicast session that fails to be established, and information (e.g., qoS flow information, etc.) of the corresponding resource. Optionally, after receiving the response message, the access network device 101 sends indication information to the terminal 103, where the indication information includes an identifier of the multicast session that fails to be established and information of a resource corresponding to the identifier. In this way, upon receiving the indication information, the terminal 103 may determine that multicast data is not received within the coverage area of the access network device 102 and/or the access network device 105.

The case where the access network device updates the second information is described below in two cases. In the first case, the terminal 103 resumes the connection state under the access network device 101, and specific procedures may refer to S405A-S407A. In the second case, the terminal 103 resumes the connection state under the access network device 102, and specific procedures may refer to S405B-S407B.

First, the first case is described:

S405A: the terminal 103 transmits an RRC connection restoration request message to the access network device 101.

Accordingly, the access network device 101 receives the RRC connection restoration request message from the terminal 103.

The RRC connection recovery request message may include an I-RNTI of the terminal 103.

It will be appreciated that after S405A, the terminal 103 enters a connected state.

Optionally, after S405A, for the above case a, the access network device 101 adds 1 to the number indicated by the first information in the access network device 101. For the case B described above, the access network device 101 does not modify the first information. For the above case C, the access network device 101 may query for the context of the terminal 103 itself stored in the multicast group. For the above case D, the access network device 101 adds the identity of the terminal 103 to the first information.

Optionally, after S405A, for case 1 above, the access network device 101 subtracts 1 from the number indicated by the second information. For case 2, the access network device 101 decreases the number of times indicated by the second information by 1. For case 3, the access network device 101 may delete its identity from the second information.

S406A: the access network device 101 sends second notification information to the access network device 102 and the access network device 105.

Accordingly, the access network device 102 and the access network device 105 receive the second notification information from the access network device 101.

In a possible implementation, in case the access network device within the RNA of any terminal in the multicast group that is switched to the inactive state by the access network device 101 and that is currently still in the inactive state does not include the access network device 102, the access network device 101 sends a second notification information to the access network device 102. Similarly, in the case where the access network device within the RNA of any terminal in the multicast group that is switched to the inactive state by the access network device 101 and is currently also in the inactive state does not include the access network device 105, the access network device 101 transmits second notification information to the access network device 105.

Illustratively, taking the multicast group including the terminal 103 and the terminal 104, where the terminal 103 is restored to the connected state under the access network device 101, and the terminal 104 is switched to the inactive state by the access network device 101 and is currently still in the inactive state, if the access network device in the RNA of the terminal 104 includes the access network device 102 but does not include the access network device 105, the access network device 101 sends the second notification information to the access network device 105 but does not send the second notification information to the access network device 102. If the access network device within the RNA of the terminal 104 does not include the access network device 102 and the access network device 105, the access network device 101 sends second notification information to the access network device 102 and the access network device 105. If the access network device within the RNA of the terminal 104 includes the access network device 102 and the access network device 105, the access network device 101 does not send the second notification information to the access network device 102 and the access network device 105.

In one possible implementation, the access network device 101 obtains a context of the terminal 103 (e.g., a locally stored context of the terminal indexed by the I-RNTI) according to the I-RNTI value provided by the terminal 103. The context of the terminal 103 includes RNA information of the terminal 103. The access network device 101 sends second notification information to the corresponding access network devices (the access network device 102 and the access network device 105 in this example) according to the RNA information of the terminal 103. Specifically, the access network device 101 sends the second notification information to the corresponding access network devices (in this example, the access network device 102 and the access network device 105) according to the RNA information of the terminal 103, where the access network device 101 may parse the corresponding base station (may parse according to a pre-configuration or may parse according to a partial field of the Cell identifier) according to the Cell information (for example, the NR Cell ID) included in the RNA information, and send the second notification information to the corresponding base station.

Optionally, the second notification information is included in an MBS session update request message.

S407A: the access network device 102 and the access network device 105 update the second information according to the second notification information.

It will be appreciated that for case 1 above, the access network device 102 reduces the number of second information indications of the access network device 102 by 1. For case 2, the access network device 102 decreases the number of times indicated by the second information of the access network device 102 by 1. For case 3, the access network device 102 may delete its identity from the second information.

It will be appreciated that for case 1 above, the access network device 105 subtracts 1 from the number indicated by the second information of the access network device 105. For case 2, the access network device 105 decreases the number of times indicated by the second information of the access network device 105 by 1. For case 3, the access network device 105 may delete its identity from the second information.

The second case is described below:

S405B: the terminal 103 transmits an RRC connection restoration request message to the access network device 102.

Accordingly, the access network device 102 receives the RRC connection restoration request message from the terminal 103.

It will be appreciated that after S405B, the terminal 103 enters a connected state.

Optionally, after S405B, for the above case a, the access network device 102 adds 1 to the number indicated by the first information in the access network device 102. For case B above, the access network device 102 does not modify the first information. For the above case C, the access network device 102 inquires of itself that the context of the terminal 103 in the multicast group is not stored, and the first information indicates that the access network device does not store the context of the terminal in the multicast group. For the case D described above, the access network device 102 adds the identification of the terminal 103 to the first information.

Optionally, after S405B, for case 1 above, the access network device 102 subtracts 1 from the number indicated by the second information. For case 2, the access network device 102 decreases the number of times indicated by the second information by 1. For case 3, the access network device 102 may delete its identity from the second information.

S406B: the access network device 102 sends the second notification information to the access network device 101 and the access network device 105.

Accordingly, the access network device 101 and the access network device 105 receive the second notification information from the access network device 102.

In a possible implementation manner, in a case where the access network device 102 is switched to the inactive state in the multicast group, and the access network device within the RNA of any terminal that is still currently in the inactive state does not include the access network device 101, the access network device 102 sends the second notification information to the access network device 101. Similarly, in the case where the access network device 102 is switched to the inactive state in the multicast group, and the access network device within the RNA of any of the terminals in the inactive state that are also currently in the inactive state does not include the access network device 105, the access network device 102 sends the second notification information to the access network device 105.

In a possible implementation manner, the access network device 102 sends a context acquisition request message of the terminal 103 to the access network device 101. Wherein the context acquisition request message of the terminal 103 may include an I-RNTI of the terminal 103. Optionally, the context acquisition request message of the terminal 103 further comprises an identification of the multicast group. After receiving the context acquisition request message of the terminal 103, the access network device 101 sends the context of the terminal 103 to the access network device 102. Subsequently, the access network device 101 deletes the context of the terminal 103.

Alternatively, for the above case B, the access network device 101 decreases the number of the first information indications by 1 after deleting the context of the terminal 103. For the above case C, after the access network device 101 deletes the context of the terminal 103, the access network device 101 does not query the context of the terminal 103, and if the access network device 101 does not store the context of the other terminals in the multicast group, the first information indicates that the access network device 101 does not store the context of the terminals in the multicast group.

It may be understood that, in S406B, the access network device 102 may not send the second notification message to the access network device 105, but the access network device 101 may send a message to the access network device 105 after receiving the context acquisition request message of the terminal 103. The message may inform the access network device 105 that one terminal in the multicast group is leaving the inactive state.

For example, the message is an MBS session update request message. The MBS session update request message may include at least one of: RNA information, identity of the multicast group or I-RNTI of the terminal 103.

S407B: the access network device 101 and the access network device 105 update the second information according to the second notification information.

It will be appreciated that for case 1 above, the access network device 101 subtracts 1 from the number indicated by the second information of the access network device 101. For case 2, the access network device 101 decreases the number of times indicated by the second information of the access network device 101 by 1. For case 3, the access network device 101 may delete its identity from the second information.

S408: the access network device 101 determines whether to release the context of the multicast session of the access network device 101 based on the first information and the second information of the access network device 101.

A possible implementation way, when the last terminal in the multicast group connected to the access network device 101 leaves the access network device 101 and there is no terminal in the multicast group in an inactive state associated with the access network device 101, the access network device 101 releases the context of the multicast session of the access network device 101, otherwise, does not release the context of the multicast session of the access network device 101.

It will be appreciated that if the access network device 101 releases the context of the multicast session of the access network device 101, the access network device 101 sends a multicast session leave message to the second network device and/or the access network device 101 sends a request message to the first network device.

S409: the access network device 102 determines whether to release the context of the multicast session of the access network device 102 based on the first information and the second information of the access network device 102.

S410: the access network device 105 determines whether to release the context of the multicast session of the access network device 105 based on the first information and the second information of the access network device 105.

It is to be understood that the processes of S409-S410 are similar to those of S408, and reference may be made to the corresponding description in S408, and will not be repeated.

The actions of the access network device 101, the access network device 102, or the access network device 105 in S401 to S410 may be performed by the processor 201 in the communication apparatus 20 shown in fig. 2 calling the application program code stored in the memory 203, which is not limited in any way in the embodiment of the present application.

Based on the method shown in fig. 4, the access network device 101, the access network device 102, or the access network device 103 may release the context of the multicast session in the case that the last terminal connected to the access network device in the multicast group leaves the access network device and there is no inactive terminal associated with the access network device in the multicast group. In this way, the terminal in the multicast group can be ensured to receive the multicast data, and the access network device can timely release the context of the multicast session corresponding to the multicast group, so as to save resources.

As shown in fig. 5, another multicast communication method according to an embodiment of the present application may include the following steps:

s501: the second access network device establishes a context for the multicast session of the second access network device.

The second access network device may be any one of the access network devices in the communication system 10 shown in fig. 1, for example, the access network device 101, the access network device 102, or the access network device 105 in fig. 1. The multicast session may be used to transmit multicast data corresponding to the multicast group.

One possible implementation manner, the second access network device establishes the context of the multicast session of the second access network device through the flow shown in S11-S13. Namely: the terminal joins the multicast group through the second access network device.

In another possible implementation, the first access network device sends the second message to the second access network device. Wherein the second message may be used to request a context for establishing a multicast session for the second access network device. After the second access network device receives the second message, the second access network device establishes the context of the multicast session of the second access network device.

Wherein the first access network device is a different access network device than the second access network device in the communication system 10 shown in fig. 1. For example, if the second access network device is the access network device 101 in fig. 1, the first access network device is the access network device 102 or the access network device 105 in fig. 1.

If the terminal joins the multicast group through the first access network device, and enters an inactive state under the first access network device, and the access network device in the RNA of the terminal includes the second access network device, the first access network device sends a second message to the second access network device to trigger the second access network device to establish a context of the multicast session of the second access network device.

S502: the first access network device sends a first message to the second access network device.

Accordingly, the second access network device receives the first message from the first access network device.

Wherein the first message may be used to indicate a context to release the multicast session.

One possible implementation way is that one terminal in the multicast group leaves the inactive state under an access network device outside the second access network device, and the first access network device sends a first message to the second access network device.

For example, if one terminal in the multicast group leaves the inactive state under the first access network device, the first access network device sends a first message to the second access network device.

For another example, if the first access network device receives a third message from the third access network device, where the third message is used to instruct the terminal in the multicast group that is switched to the inactive state by the first access network device to restore to the connected state at the third access network device, or the third message is used to request the first access network device to send the context of the terminal to the third access network device, the first access network device sends the first message to the second access network device.

In one possible implementation, if the RNA of each terminal in the multicast group that is switched to the inactive state by the first access network device and is still currently in the inactive state does not include the coverage area of the second access network device, the first access network device sends a first message to the second access network device.

S503: the second access network device releases the context of the multicast session of the second access network device.

In one possible implementation manner, the second access network device determines that a last terminal connected to the second access network device in the multicast group leaves the second access network device, and that no inactive terminal associated with the second access network device exists in the multicast group, and the second access network device releases a context of the multicast session of the second access network device. Specifically, reference may be made to corresponding descriptions in the methods shown in fig. 3A, 3B or 4, which are not described herein.

The actions of the first access network device or the second access network device in S501-S503 may be performed by the processor 201 in the communication apparatus 20 shown in fig. 2 calling the application program code stored in the memory 203, which is not limited in any way in the embodiment of the present application.

Based on the method shown in fig. 5, after the second access network device establishes the context of the multicast session of the second access network device, a message indicating to release the context of the multicast session from the first access network device may be received, and according to the message, the context of the multicast session is timely released.

It will be appreciated that in the various embodiments above, the methods and/or steps implemented by the access network device may also be implemented by a component (e.g., a chip or circuit) that may be used in the access network device.

The above description has been presented mainly from the point of interaction between the network elements. Correspondingly, the embodiment of the application also provides a communication device, which can be the first access network equipment in the embodiment of the method, or a device containing the first access network equipment, or a component applicable to the first access network equipment; alternatively, the communication apparatus may be the second access network device in the above method embodiment, or an apparatus including the second access network device, or a component that may be used in the second access network device. It will be appreciated that, in order to implement the above-mentioned functions, the first access network device or the second access network device or the like includes corresponding hardware structures and/or software modules for performing the respective functions. Those of skill in the art will readily appreciate that the elements and algorithm operations described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is implemented as hardware or computer software driven 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.

It should be appreciated that the above describes interactions between various network elements by way of example only of an access network device. In practice, the processing performed by the access network device described above is not limited to being performed by only a single network element. For example, the processing performed by the access network device may be performed by at least one of a Central Unit (CU), a Distributed Unit (DU), and a Remote Unit (RU), respectively.

The embodiment of the application may divide the functional modules of the first access network device or the second access network device according to the above method example, 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 modules may be implemented in hardware or in software functional modules. It should be understood that the division of the modules in the embodiments of the present application is merely a logic function division, and other division manners may be implemented in practice.

For example, in the case where the respective functional modules are divided in an integrated manner, fig. 6 shows a schematic configuration of a communication apparatus 60. The communication device 60 comprises a processing module 601. Optionally, the communication device further comprises a transceiver module 602. The processing module 601 may also be referred to as a processing unit for performing operations other than transceiving operations, and may be, for example, a processing circuit or a processor, etc. The transceiver module 602, which may also be referred to as a transceiver unit, is configured to perform a transceiver operation, and may be, for example, a transceiver circuit, a transceiver, or a communication interface.

In some embodiments, the communication device 60 may also include a memory module (not shown in fig. 6) for storing program instructions and data.

The communication means 60 are illustratively arranged to implement the functionality of an access network device, such as the first access network device, the access network device 101, the access network device 102 or the access network device 105. The communication means 60 is, for example, a first access network device according to the embodiment shown in fig. 3A or fig. 3B, and an access network device 101, an access network device 102 or an access network device 105 according to the embodiment shown in fig. 4.

The processing module 601 is configured to determine that a last terminal connected to the communication device 60 in a multicast group leaves the communication device 60, and that no inactive terminal associated with the communication device 60 exists in the multicast group. For example, the processing module 601 may be used to perform S301.

The processing module 601 is further configured to release the context of the multicast session of the communication device 60. The multicast session is used for transmitting multicast data corresponding to the multicast group. For example, the processing module 601 may also be used to perform S302.

In one possible implementation, the transceiver module 602 is configured to send a request message to the first network device, where the request message is used to request release of the multicast session; the transceiver module 602 is further configured to receive a response message from the first network device, where the response message is used to respond to the request message.

In a possible implementation, the transceiver module 602 is further configured to send a multicast session leave message to the second network device, where the multicast session leave message is used to trigger to release a context of a multicast session of the second network device, and the multicast session of the second network device is used to transmit multicast data corresponding to the multicast group.

In one possible implementation, the last terminal in the multicast group connected to the communication device 60 leaves the communication device 60, including: the last terminal in the multicast group to which the communication device 60 is connected is deleted by the communication device 60 from the context of the multicast session; alternatively, the last terminal in the multicast group connected to the communication device 60 switches to an access network device other than the communication device 60.

In a possible implementation manner, the processing module 601 is specifically configured to determine that a last terminal connected to the communication device 60 in the multicast group leaves the communication device 60 according to first information of a terminal in a connection state associated with the communication device 60 in the multicast group.

In one possible implementation, the first information is used to indicate the number of terminals in the multicast group that are connected to the communication device 60 and in a connected state, or the first information is used to indicate the number of contexts of terminals in the multicast group stored in the communication device 60.

In a possible implementation manner, the processing module 601 is specifically configured to determine that, according to the second information of the inactive terminal associated with the communication device 60 in the multicast group, there is no inactive terminal associated with the communication device 60 in the multicast group.

In one possible implementation, the inactive terminals associated with the communication device 60 in the multicast group include: a terminal in the multicast group switched to an inactive state by the communication device 60; and a terminal in the multicast group switched to an inactive state by other access network devices than the communication apparatus 60, and a radio access network notification area of the terminal includes all or a part of the coverage area of the communication apparatus 60.

In a possible implementation manner, the transceiver module 602 is further configured to receive first notification information from the second access network device, where the first notification information is used to notify that one terminal in the multicast group is switched to an inactive state, or the first notification information is used to notify that there are terminals in the multicast group that are switched to an inactive state by the second access network device, or the first notification information is used to notify that the number of terminals in the multicast group that are switched to an inactive state by the second access network device; the processing module 601 is further configured to update the second information according to the first notification information.

In a possible implementation manner, the transceiver module 602 is further configured to receive second notification information from the second access network device, where the second notification information is used to notify that one terminal in the multicast group leaves an inactive state, or the second notification information is used to notify that no terminal switched to the inactive state by the second access network device exists in the multicast group, or the second notification information is used to notify the number of terminals leaving the inactive state under the second access network device in the multicast group; the processing module 601 is further configured to update the second information according to the second notification information.

In one possible implementation, the second information is used to indicate the number of inactive terminals associated with the communication device 60 in the multicast group or the number of uses of the context of the multicast session.

In a possible implementation manner, the processing module 601 is specifically configured to determine that there is no terminal in the multicast group in an inactive state associated with the communication device 60 when the number of terminals indicated by the second information is zero or the number of times indicated by the second information is zero.

In a possible implementation manner, the transceiver module 602 is further configured to send, to at least one access network device, third notification information if the first terminal in the multicast group is switched to the inactive state, where the third notification information is used to notify that one terminal in the multicast group is switched to the inactive state, or the third notification information is used to notify that there is a terminal in the multicast group that is switched to the inactive state by the communication device 60.

In one possible implementation, the first terminal is a terminal in the multicast group that is switched to an inactive state by the communication device 60.

In a possible implementation manner, the transceiver module 602 is further configured to send fourth notification information to the at least one access network device, where the first terminal returns from the inactive state to the connected state under the communication apparatus 60, where the fourth notification information is used to notify one terminal in the multicast group that the terminal leaves the inactive state; or, the transceiver module 602 is further configured to send fifth notification information to an access network device other than the third access network device in the at least one access network device, where the first terminal leaves the active state from the third access network device, where the fifth notification information is used to notify that one terminal in the multicast group leaves the inactive state.

In a possible implementation manner, the transceiver module 602 is further configured to send, when a last terminal in the multicast group of the terminals switched to the inactive state by the communication device 60 leaves the inactive state, sixth notification information to the at least one access network device, where the sixth notification information is used to notify that the number of terminals in the multicast group that are switched to the inactive state by the communication device 60 is 0, or the sixth notification information is used to notify that there are no terminals in the multicast group that are switched to the inactive state by the communication device 60.

When used to implement the functions of the first access network device, the access network device 101, the access network device 102, or the access network device 105, the description of the other functions that can be implemented by the communication apparatus 60 may be omitted herein with reference to the embodiment shown in fig. 3A or fig. 3B or the relevant description of the embodiment of the method shown in fig. 4.

Alternatively, the communication means 60 are for example arranged to implement the functionality of the second access network device. The communication means 60 is for example a second access network device as described in the embodiment shown in fig. 5.

Wherein the processing module 601 is configured to establish a context of a multicast session of the communication device 60. The multicast session is used for transmitting multicast data corresponding to the multicast group. For example, the processing module 601 may be configured to execute S501.

A transceiver module 602, configured to receive a first message from a first access network device. Wherein the first message is for indicating to release a context of the multicast session. For example, the transceiver module 602 may be used to perform S502.

The processing module 601 is further configured to release the context of the multicast session. For example, the processing module 601 may be used to perform S503.

In a possible implementation, the transceiver module 602 is further configured to receive a second message from the first access network device, where the second message is used to request the communication apparatus 60 to establish the context of the multicast session.

In one possible implementation, the processing module 601 is specifically configured to release the context of the multicast session when the last terminal in the multicast group connected to the communication device 60 leaves the communication device 60 and there is no inactive terminal associated with the communication device 60 in the multicast group.

When used to implement the functions of the second access network device, the other functions that can be implemented by the communication device 60 may be referred to in the related description of the embodiment shown in fig. 5, which is not repeated.

In a simple embodiment, one skilled in the art will recognize that the communication device 60 may take the form shown in FIG. 2. For example, the processor 201 in fig. 2 may cause the communication device 60 to perform the method described in the above-described method embodiment by invoking computer-executable instructions stored in the memory 203.

Illustratively, the functions/implementations of the processing module 601 and transceiver module 602 in fig. 6 may be implemented by the processor 201 in fig. 2 invoking computer-executable instructions stored in the memory 203. Alternatively, the functions/implementation of the processing module 601 in fig. 6 may be implemented by the processor 201 in fig. 2 calling computer-executable instructions stored in the memory 203, and the functions/implementation of the transceiver module 602 in fig. 6 may be implemented by the communication interface 204 in fig. 2.

For example, in the case where the respective functional modules are divided in an integrated manner, fig. 7 shows a schematic configuration of a communication apparatus 70. The communication device 70 comprises a transceiver module 701. The transceiver module 701 may also be referred to as a transceiver unit for performing a transceiver operation, and may be, for example, a transceiver circuit, a transceiver, or a communication interface.

Illustratively, the communication means 70 is arranged to implement the functionality of the first access network device. The communication means 70 is for example a first access network device as described in the embodiment shown in fig. 5.

Wherein, the transceiver module 701 is configured to send a second message to the second access network device. The second message is used for requesting to establish the context of a multicast session of the second access network device, where the multicast session is used for transmitting multicast data corresponding to the multicast group. And/or; the transceiver module 701 is further configured to send a first message to the second access network device, where the first message is used to indicate to release the context of the multicast session.

In a possible implementation manner, the transceiver module 701 is specifically configured to send the first message to the second access network device if the coverage area of the second access network device is not included in the radio access network notification area of each terminal in the multicast group that is switched to the inactive state by the communication device and is still in the inactive state currently; or, the transceiver module 701 is specifically configured to, if the communication apparatus receives a third message from a third access network device, instruct a terminal in the multicast group that is switched to an inactive state by the communication apparatus to restore to a connected state at the third access network device, or request the communication apparatus to send a context of the terminal to the third access network device, and send the first message to the second access network device.

When used to implement the function of the first access network device, the other functions that can be implemented by the communication device 70 may be referred to in the related description of the embodiment shown in fig. 5, which is not repeated.

In a simple embodiment, one skilled in the art will recognize that the communication device 70 may take the form shown in FIG. 2. For example, the processor 201 in fig. 2 may cause the communication device 70 to perform the method described in the above method embodiment by invoking computer-executable instructions stored in the memory 203.

Illustratively, the functions/implementations of transceiver module 701 in fig. 7 may be implemented by processor 201 in fig. 2 invoking computer-executable instructions stored in memory 203. Alternatively, the functions/implementation of the transceiver module 701 in fig. 7 may be implemented by the communication interface 204 in fig. 2.

It is to be understood that one or more of the above modules or units may be implemented in software, hardware, or a combination of both. When any of the above modules or units are implemented in software, the software exists in the form of computer program instructions and is stored in a memory, a processor can be used to execute the program instructions and implement the above method flows. The processor may be built in a SoC (system on a chip) or ASIC, or may be a separate semiconductor chip. The processor may further include necessary hardware accelerators, such as field programmable gate arrays (field programmable gate array, FPGAs), PLDs (programmable logic devices), or logic circuits implementing dedicated logic operations, in addition to the cores for executing software instructions for operation or processing.

When the above modules or units are implemented in hardware, the hardware may be any one or any combination of a CPU, microprocessor, digital signal processing (digital signal processing, DSP) chip, micro control unit (microcontroller unit, MCU), artificial intelligence processor, ASIC, soC, FPGA, PLD, special purpose digital circuitry, hardware accelerator, or non-integrated discrete devices that may run the necessary software or that do not rely on software to perform the above method flows.

Optionally, an embodiment of the present application further provides a chip system, including: at least one processor and an interface, the at least one processor being coupled with the memory through the interface, the at least one processor, when executing the computer programs or instructions in the memory, causing the method of any of the method embodiments described above to be performed. In one possible implementation, the system on a chip further includes a memory. Alternatively, the chip system may be formed by a chip, or may include a chip and other discrete devices, which are not specifically limited in this embodiment of the present application.

Optionally, embodiments of the present application further provide a computer-readable storage medium. All or part of the flow in the above method embodiments may be implemented by a computer program to instruct related hardware, where the program may be stored in the above computer readable storage medium, and when the program is executed, the program may include the flow in the above method embodiments. The computer readable storage medium may be an internal storage unit of the communication device of any of the foregoing embodiments, such as a hard disk or a memory of the communication device. The computer readable storage medium may be an external storage device of the communication apparatus, for example, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash card (flash card) or the like provided in the communication apparatus. Further, the computer readable storage medium may further include both an internal storage unit and an external storage device of the communication apparatus. The computer-readable storage medium is used to store the computer program and other programs and data required by the communication 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.

Optionally, the embodiment of the application further provides a computer program product. All or part of the above-described method embodiments may be implemented by a computer program to instruct related hardware, where the program may be stored in the above-described computer program product, and the program, when executed, may include the above-described method embodiments.

Optionally, the embodiment of the application further provides a computer instruction. All or part of the flow in the above method embodiments may be implemented by computer instructions to instruct related hardware (such as a computer, a processor, an access network device, a mobility management network element, or a session management network element, etc.). The program may be stored in the above-mentioned computer readable storage medium or in the above-mentioned computer program product.

Optionally, an embodiment of the present application further provides a communication system, including: the first access network device in the embodiment shown in fig. 3A or fig. 3B. Optionally, the communication system further includes: the first network device and/or the second network device in the embodiment shown in fig. 3A.

Optionally, an embodiment of the present application further provides a communication system, including: access network device 101, access network device 102, and access network device 105 in the embodiment shown in fig. 4. Optionally, the communication system further includes: terminal 103 in the embodiment shown in fig. 4.

Optionally, an embodiment of the present application further provides a communication system, including: the first access network device and the second access network device in the embodiment shown in fig. 5.

From the foregoing description of the embodiments, it will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of functional modules is illustrated, and in practical application, the above-described functional allocation may be implemented by different functional modules, that is, the internal structure of the apparatus is divided into different functional modules, so as to implement all or part of the functions described above.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the modules or units is merely a logical functional division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another apparatus, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

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

In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The foregoing is merely a specific embodiment of the present application, but the protection 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 in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of multicast communication, applied to a first access network device, the method comprising:

Determining that a last terminal connected with the first access network device in a multicast group leaves the first access network device, and that no inactive terminal associated with the first access network device exists in the multicast group;

releasing the context of the multicast session of the first access network device, where the multicast session is used to transmit multicast data corresponding to the multicast group.

2. The method of claim 1, wherein after determining that a last terminal in a multicast group connected to the first access network device leaves the first access network device and that there is no inactive terminal in the multicast group associated with the first access network device, the method further comprises:

transmitting a request message to a first network device, the request message being for requesting release of the multicast session;

before said releasing the context of the multicast session of the first access network device, the method further comprises:

a response message is received from the first network device, the response message being for responding to the request message.

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

And sending a multicast session leaving message to a second network device, wherein the multicast session leaving message is used for triggering and releasing the context of the multicast session of the second network device, and the multicast session of the second network device is used for transmitting multicast data corresponding to the multicast group.

4. A method according to any of claims 1-3, characterized in that the last terminal in the multicast group connected to the first access network device leaves the first access network device, comprising:

the last terminal in the multicast group connected to the first access network device is deleted by the first access network device from the context of the multicast session; or,

and switching the last terminal connected with the first access network device in the multicast group to access network devices except the first access network device.

5. The method according to any of claims 1-4, wherein said determining that a last terminal in a multicast group connected to the first access network device leaves the first access network device comprises:

and determining that the last terminal connected with the first access network equipment in the multicast group leaves the first access network equipment according to the first information of the terminal in the connection state associated with the first access network equipment in the multicast group.

6. The method of claim 5, wherein the first information is used to indicate a number of terminals in the multicast group that are connected to the first access network device and in a connected state, or the first information is used to indicate a number of contexts of terminals in the multicast group stored in the first access network device.

7. The method according to any of claims 1-6, wherein the determining that there are no inactive terminals in the multicast group associated with the first access network device comprises:

and determining that the terminal in the inactive state associated with the first access network equipment does not exist in the multicast group according to the second information of the terminal in the inactive state associated with the first access network equipment in the multicast group.

8. The method of claim 7, wherein the inactive terminals in the multicast group associated with the first access network device comprise: a terminal in the multicast group switched to an inactive state by the first access network device; and a terminal in the multicast group switched to an inactive state by an access network device other than the first access network device, and a radio access network notification area of the terminal includes all or a part of a coverage area of the first access network device.

9. The method according to claim 7 or 8, characterized in that the method further comprises:

receiving first notification information from a second access network device, where the first notification information is used to notify that one terminal in the multicast group is switched to an inactive state, or the first notification information is used to notify that a terminal in the multicast group is switched to an inactive state by the second access network device, or the first notification information is used to notify the number of terminals in the multicast group which are switched to an inactive state by the second access network device;

and updating the second information according to the first notification information.

10. The method according to claim 9, wherein the method further comprises:

receiving second notification information from the second access network device, where the second notification information is used to notify that one terminal in the multicast group leaves an inactive state, or the second notification information is used to notify that no terminal switched to the inactive state by the second access network device exists in the multicast group, or the second notification information is used to notify the number of terminals that leave the inactive state under the second access network device in the multicast group;

And updating the second information according to the second notification information.

11. The method according to any of claims 7-10, wherein the second information is used to indicate the number of inactive terminals associated with the first access network device in the multicast group or the number of uses of the context of the multicast session.

12. The method according to any of claims 7-11, wherein the determining that there are no inactive terminals associated with the first access network device in the multicast group based on second information of inactive terminals associated with the first access network device in the multicast group comprises:

and when the number of the terminals indicated by the second information is zero or the number of times indicated by the second information is zero, determining that no inactive terminal associated with the first access network device exists in the multicast group.

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

and if the first terminal in the multicast group is switched to the inactive state, sending third notification information to at least one access network device, wherein the third notification information is used for notifying that one terminal in the multicast group is switched to the inactive state, or the third notification information is used for notifying that the terminal switched to the inactive state by the first access network device exists in the multicast group.

14. The method of claim 13, wherein the first terminal is a terminal in the multicast group that is switched to an inactive state by the first access network device.

15. The method according to claim 13 or 14, characterized in that the method further comprises:

sending fourth notification information to the at least one access network device under the condition that the first terminal is recovered from an inactive state to a connected state under the first access network device, wherein the fourth notification information is used for notifying one terminal in the multicast group to leave the inactive state; or,

and sending fifth notification information to access network equipment except for the third access network equipment in the at least one access network equipment under the condition that the first terminal leaves the activated state from the third access network equipment, wherein the fifth notification information is used for notifying one terminal in the multicast group to leave the deactivated state.

16. The method of claim 15, wherein the method further comprises:

and when the last terminal in the multicast group, which is switched to the inactive state by the first access network device, leaves the inactive state, sending sixth notification information to the at least one access network device, where the sixth notification information is used to notify that the number of the terminals, which are switched to the inactive state by the first access network device, in the multicast group is 0, or the sixth notification information is used to notify that no terminal, which is switched to the inactive state by the first access network device, exists in the multicast group.

17. A communication device comprising means or modules for performing the method of any one of claims 1 to 16.

18. A communication device, comprising: a processor coupled to a memory for storing a program or instructions that, when executed by the processor, cause the apparatus to perform the method of any one of claims 1 to 16.

19. A chip, comprising: a processor coupled to a memory for storing a program or instructions that, when executed by the processor, cause the chip to perform the method of any one of claims 1 to 16.

20. A computer readable storage medium having stored thereon a computer program or instructions, which when executed cause a computer to perform the method of any of claims 1 to 16.

21. A computer program product comprising computer program code for causing a computer to carry out the method of any one of claims 1 to 16 when said computer program code is run on a computer.

22. A communication system, comprising: access network device for performing the method of any of claims 1 to 16.

23. The communication system of claim 22, wherein the communication system further comprises: a first network device, the first network device configured to: and receiving a request message, wherein the request message is used for requesting to release the multicast session, and sending a response message of the request message to the access network equipment.

24. A communication system according to claim 22 or 23, characterized in that the communication system further comprises: a second network device, the second network device configured to: and receiving a multicast session leaving message, and releasing the context of the multicast session of the second network device according to the multicast session leaving message, wherein the multicast session of the second network device is used for transmitting multicast data corresponding to the multicast group.