WO2021223745A1

WO2021223745A1 - Multicast service switching method and apparatus

Info

Publication number: WO2021223745A1
Application number: PCT/CN2021/092205
Authority: WO
Inventors: 宗在峰; 朱奋勤
Original assignee: 华为技术有限公司
Priority date: 2020-05-08
Filing date: 2021-05-07
Publication date: 2021-11-11
Also published as: CN113630822B; CN113630822A

Abstract

Provided in the embodiments of the present application are a multicast service switching method and apparatus. The method comprises: when the signal in a multicast area where a terminal device in a first network is located is weak, a first session management network element receiving first indication information, wherein the first indication information is used to indicate the transmission of a data packet of a service to the terminal device by means of a unicast bearer; the first session management network element transmitting second indication information to a first user plane network element, wherein the second indication information is used to indicate the transmission of the data packet to the terminal device by means of the unicast bearer; and when the terminal device gains access by means of a second network, the first session management network element adding the terminal device to a multicast session corresponding to the service. Switching data of a service from a multicast path of a first network to a unicast bearer of the first network, and then switching the data from the unicast bearer of the first network to a multicast session of a second network can ensure the continuity of the multicast service data during the process of cell switching.

Description

Method and device for switching multicast services

This application claims the priority of the Chinese patent application filed with the Chinese Patent Office on May 8, 2020, the application number is 202010383204.3, and the application name is "Method and Device for Multicast Service Switching", and it is filed in China on July 31, 2020 The patent office, the application number is 202010756685.8, the priority of the Chinese patent application with the application name "Multicast Service Switching Method and Device", the entire content of which is incorporated into this application by reference.

Technical field

This application relates to the field of communication technology, and in particular to a method and device for switching multicast services.

Background technique

In the Long Term Evolution (LTE) system network, for group communication (Group Communication) services, the application server (Application Services) can send multicast broadcast service data (also known as MBMS services) to Terminal equipment: Multimedia Broadcast/Multicast Services (MBMS) bearer or unicast bearer.

When the terminal device is located within the coverage of the fifth generation mobile communication (5Generation, 5G) network, the terminal device can also receive multicast broadcast service data in the form of multicast broadcast. The 5G network is also called the New Radio (New Radio) system . In a 5G network, the AS can also send multicast broadcast service data to terminal devices in two ways: 5G multicast broadcast path or unicast path.

In the LTE system, MBMS has a certain service area. When the terminal equipment moves from the MBMS area to the coverage of the 5G base station, how to ensure the continuity of the multicast broadcast service data during the handover process is a key issue that needs to be solved.

Summary of the invention

The embodiments of the present application provide a method and device for switching multicast services, which can ensure that when a terminal device switches from a first network to a second network, the multicast service data received by the terminal device through the multicast path of the first network is Maintain business continuity during the handover.

The first aspect of the present application provides a method for switching multicast services, including: a first session management network element receives first indication information, where the first indication information is used to indicate to a terminal device located on a first network through a unicast bearer Send business data packets. The first session management network element sends second indication information to the first user plane network element, where the second indication information is used to indicate that the data packet is sent to the terminal device through the unicast bearer. When the terminal device accesses through the second network, the first session management network element adds the terminal device to the multicast session corresponding to the service.

In this method, the service data is first switched from the multicast path of the first network to the unicast bearer of the first network, and then the unicast bearer of the first network is switched to the multicast session of the second network, thereby ensuring that the terminal When the device is switched from the first network to the second network, the multicast service data received by the terminal device through the multicast path of the first network maintains service continuity during the switching process.

In an exemplary manner, the method further includes: the first session management network element obtains multicast service quality QoS flow information of the service, and determines to send the service according to the multicast QoS flow information of the service The unicast bearer of the data packet.

In an exemplary manner, the first session management network element receiving the first indication information includes: the first session management network element receiving a first message, the first message including the first indication information and The multicast service identifier of the service. Correspondingly, the first session management network element acquiring the multicast QoS flow information of the service includes: the first session management network element acquiring the multicast QoS flow information of the service according to the multicast service identifier.

In another exemplary manner, the first indication information includes a multicast service identifier of the service, and the first session management network element acquiring multicast QoS flow information of the service includes: the first The session management network element obtains the multicast QoS flow information of the service according to the multicast service identifier.

In an exemplary manner, the method further includes: if the first session management network element receives eighth indication information, the eighth indication information indicates that the service supports service continuity, then the first The session management network element determines the unicast QoS flow corresponding to the service according to the information of the multicast QoS flow.

In an exemplary manner, adding the terminal device to the multicast session corresponding to the service by the first session management network element is specifically: when the terminal device moves from the first network to the second During the network switching process, the first session management network element switches the data packets of the service from being sent to the terminal device via the unicast bearer to being sent to the terminal device via a protocol data unit PDU session. After the terminal device is switched from the first network to the second network, the first session management network element joins the terminal device to the multicast session, and the service data packet passes through the The PDU session sent to the terminal is switched to sent to the terminal device through the multicast session.

The PDU session is a unicast path in the second network. In this way, the data packet transmitted by the multicast mode in the first network is first switched from the multicast mode to the unicast path of the first network, and then from the first network. Switch from the unicast path of the second network to the unicast path of the second network, and then switch from the unicast path of the second network to the multicast path of the second network, so as to ensure that the multicast service of the terminal equipment maintains business continuity during the cell switching process sex.

Optionally, after the terminal device joins the multicast session, the first user plane network element is notified to stop sending the service data to the terminal device through the PDU session.

In another exemplary manner, adding the terminal device to the multicast session corresponding to the service by the first session management network element is specifically: when the terminal device is transferred from the first network to the first network 2. During the network switching process, the first session management network element joins the terminal device to the multicast session, and the service data packet is switched from being sent to the terminal device via the unicast bearer to passing through the The multicast session is sent to the terminal device.

This method first switches the data packets transmitted through the multicast mode in the first network from the multicast mode to the unicast path of the first network, and then switches from the unicast path of the first network to the multicast path of the second network. This ensures that the multicast service of the terminal equipment maintains service continuity during the cell handover.

Optionally, before the first session management network element joins the terminal device to the multicast session, the first session management network element determines that the service supports sending through the multicast mode of the second network.

Optionally, that the first session management network element determines that the service supports sending through the multicast mode of the second network may be: the first session management network element receives the first rule corresponding to the service, The first rule is used to perform control, policy, or charging, and the first rule includes third indication information, and the third indication information is used to indicate that the service supports multicast transmission.

Optionally, the first rule further includes a multicast service identifier corresponding to the service.

Optionally, the third indication information is a multicast service identifier corresponding to the service.

In an exemplary manner, the first indication information and the first rule are carried in the same message, or the first session management network element receives the first indication information before receiving the first indication information. One rule.

Optionally, before the first session management network element joins the terminal device to the multicast session, it determines that the terminal device supports multicast in the second network, and/or the target access network device Multicast is supported, wherein the terminal device accesses the second network through the target access network device.

Optionally, if the first session management network element determines that the terminal device supports multicast in the second network, it may be: the first session management network element establishes a packet data network PDN connection on the terminal device In the process, receiving multicast capability indication information sent by the terminal device, where the multicast capability indication information is used to indicate the multicast capability of the terminal device in the second network. The first session management network element determines, according to the multicast capability indication information, that the terminal device supports multicast in the second network.

Optionally, if the multicast session corresponding to the service has not been established, the first session management network element triggers the establishment of the multicast session.

In an exemplary manner, adding the terminal device to the multicast session by the first session management network element includes: the first session management network element receiving a request sent by an access and mobility management function AMF Message, the request message is used to create or update a PDU session, and the PDU session is associated with the service. The first session management network element determines that the service sent through the unicast bearer supports multicast transmission, and the terminal device supports the multicast service in the second network, and the first session management network The element instructs the target access network device in the second network to join the terminal device in the multicast session.

In an exemplary manner, when the terminal device moves into the MBMS area or after it moves into the MBMS area, the first session management network element receives fourth indication information, and the fourth indication information is used to instruct to stop passing through the The unicast bearer sends the data of the service, and the first session management network element notifies the first user plane network element to stop sending the data of the service through the unicast bearer according to the fourth instruction information.

In an exemplary manner, the second indication information includes a first mapping relationship between the information of the first tunnel and the identifier QFI of the multicast quality of service QoS flow of the service, and the first tunnel is the unicast Bears the corresponding tunnel, the QFI is the QFI of the service data packet received by the first user plane network element, and the first mapping relationship is used by the first user plane network element to determine to send the service The first tunnel of the packet.

Correspondingly, after the first session management network element sends the second indication information to the first user plane network element, the first session management network element receives the second tunnel information from the first user plane network element, so The first user plane network element receives the service data packet from a second user plane network element or an application server through the second tunnel, and the first session management network element sends the second tunnel information to the The second user plane network element or the application server.

In an exemplary manner, the second indication information includes the multicast address, and the second indication information is used to instruct the first user plane network element to set the destination address as the data of the multicast address The packet is sent to the terminal device through the unicast bearer.

In an exemplary manner, after the terminal device switches to the second network, the first session management network element sends a first notification message to the AS, and the first notification message is used to notify the AS to support Send the data of the service to the terminal device in a multicast manner. Correspondingly, adding the terminal device to the multicast session corresponding to the service by the first session management network element is specifically: the first session management network element receives fifth indication information, and the fifth indication information is used for After instructing to add the terminal device to the multicast session corresponding to the service, the first session management network element adds the terminal to the multicast session corresponding to the service according to the fifth instruction information.

Optionally, before the first session management network element sends the first notification message to the AS, the first session management network element receives sixth indication information, where the sixth indication information is used to indicate when the multicast mode is supported When sending service data to the terminal device, the first notification message is sent to the AS.

Optionally, the first message including the first indication information and the sixth indication information are carried in the first message.

Optionally, before the first session management network element joins the terminal to the multicast session corresponding to the service according to the fifth instruction information, the first session management network element determines that the terminal device is in the The second network supports multicast, and/or the target access network device supports multicast, wherein the terminal device accesses the second network through the target access network device.

A second aspect of the present application provides a method for switching multicast services, including: a first session management network element obtains a multicast service identifier of the service, and the first session management network element provides services for PDN connections of terminal devices;

Acquiring, by the first session management network element, the multicast QoS flow information of the service according to the multicast service identifier;

When the terminal device accesses through the second network, the first session management network element adds the terminal device to the multicast session corresponding to the service.

In this method, the first session management network element obtains the multicast service identifier of the service received by the terminal device through the multicast path of the first network in advance, and obtains the multicast QoS flow information of the service according to the multicast service identifier, so that the When a terminal device accesses through the second network, the first session management network element can add the terminal device to the multicast session corresponding to the service, thereby ensuring that the terminal device passes through the process when the terminal device switches from the first network to the second network The multicast service data received by the multicast path of the first network maintains service continuity during the switching process.

In an exemplary manner, adding the terminal device to the multicast session corresponding to the service by the first session management network element is specifically: when the terminal device moves from the first network to the second During the network switching process, the first session management network element creates a unicast QoS flow in the second network according to the multicast QoS flow information, the unicast QoS flow belongs to a PDU session, and the PDU session is connected to the Corresponding to the PDN connection, the service is sent to the terminal device through the PDU session. After the terminal device is switched from the first network to the second network, the first session management network element joins the terminal device to the multicast session, and the service data packet passes through the The PDU session is sent to the terminal device to switch to the multicast session via the second network and sent to the terminal device.

The PDU session is a unicast path in the second network. This method switches the data transmitted through the multicast mode in the first network to the unicast path of the second network, and then switches from the unicast path of the second network to the unicast path of the second network. The multicast path of the second network ensures that the multicast service of the terminal equipment maintains service continuity during the cell handover process.

In another exemplary manner, adding the terminal device to the multicast session corresponding to the service by the first session management network element is specifically: when the terminal device is transferred from the first network to the first network 2. During the network switching process, the first session management network element joins the terminal device to the multicast session according to the multicast service identifier, and the data packets of the service are transferred from the multicast mode through the first network Sent to the terminal device to switch to the multicast session via the second network and sent to the terminal device.

This method directly switches the data packets transmitted through the multicast mode in the first network to the multicast path of the second network, thereby ensuring that the multicast service of the terminal device maintains service continuity during the cell switching process.

In an exemplary manner, the method further includes: the first session management network element receives the multicast service identifier from the terminal device, or the first session management network element receives the multicast service identifier from the AS Multicast service identifier.

In an exemplary manner, the method further includes: the first session management network element receiving the multicast service identifier from the terminal device includes: the terminal device connects to the first The session management network element sends the multicast service identifier.

The terminal device sends the identifier of the multicast service through the PDN connection, so that the first session management network element associates the service with the PDN connection, so that when the terminal device switches to the second network, the first A session management network element can associate the service with the PDU session corresponding to the PDN connection, so that the terminal device can be added to the multicast session through the PDU session.

In an exemplary manner, the method further includes: the first session management network element determines that the terminal device is accessed through the first network, and the first session management network element is connected from the terminal device After receiving the multicast service identifier, not adding the terminal device to the multicast session and/or not creating a unicast bearer for the terminal device on the first network.

A third aspect of the present application provides a method for switching multicast services, including: an AS receives a first report from a terminal device, the first report being used to instruct the terminal device to move out of the MBMS area. According to the first report, the AS determines to send service data packets to the terminal device through a unicast bearer, the AS sends first indication information to the core network device and/or the first session management network element, and the The first indication information is used to indicate that the data packet of the service is sent to the terminal device through a unicast bearer.

When the signal in the MBMS area of the terminal device is weak, the method sends a first report to the AS, so that the AS triggers the establishment of a unicast bearer, switches the service from the MBMS bearer to the unicast bearer, and further switches the service from the unicast bearer In the multicast session to the second network, so as to ensure the continuity of the multicast service during the cell handover.

Optionally, the AS further sends a multicast service identifier corresponding to the service to the core network device and/or the first session management network element.

In an exemplary manner, the first indication information includes a multicast service identifier corresponding to the service.

In another exemplary manner, the AS sends a first message to the first session management network element, where the first message includes the first indication information and a multicast service identifier corresponding to the service. Alternatively, the AS sends a second message to the core network device, where the second message includes the first indication information and a multicast service identifier corresponding to the service.

Optionally, the AS further sends the eighth indication information to the core network device and/or the first session management network element, where the eighth indication information indicates that the service supports service continuity.

Optionally, the AS further sends third indication information to the core network device and/or the first session management network element, where the third indication information is used to indicate that the service supports multicast transmission.

Optionally, the AS sending third indication information to the core network device includes: the AS sends a second message to the core network device, and the second message includes the third indication information and the core network device. The multicast service identifier corresponding to the service.

Optionally, the AS further sends eighth indication information to the core network device or the first session management network element, where the eighth indication information is used to indicate that the service supports service continuity.

Optionally, the AS sends sixth indication information to the core network device, where the sixth indication information is used to indicate that when it supports sending service data to the terminal device in a multicast manner, the AS sends the The first notification message.

Optionally, the first indication information and the sixth indication information are carried in a first message or a second message.

In an exemplary manner, the AS receives a first notification message, and the first notification message is used to notify that it supports the use of multicast to send the service data to the terminal device, and responds to the first notification Message, the AS sends a second notification message to the terminal device, where the second notification message is used to notify the terminal device to use the multicast session to receive the data of the service.

In another exemplary manner, the AS receives a first notification message, where the first notification message is used to notify that it supports the use of multicast to send the service data to the terminal device, and responds to the first notification message. In a notification message, the AS sends fifth instruction information to the first session management network element or core network device, where the fifth instruction information is used to instruct the terminal device to join the multicast session corresponding to the service.

In an exemplary manner, when the terminal device moves from a non-MBMS area into an MBMS area, the AS receives a second report from the terminal device, and the second report is used to notify the AS of the terminal device The data of the service can be received through the MBMS bearer. Correspondingly, the AS sends fourth indication information to the core network device, where the fourth indication information is used to instruct to stop sending the data of the service through the unicast bearer.

The fourth aspect of the present application provides a method for switching multicast services. In the process of establishing a PDN connection, a terminal device sends multicast capability indication information to a first session management network element, where the multicast capability indication information is used to indicate all The multicast capability of the terminal device in the second network. The terminal device receives from the source access network device in the first network the configuration information of the wireless resource allocated by the target access network device in the second network to the terminal device, and the configuration information of the wireless resource is used for The terminal device receives the data of the service in the second network in a multicast manner, and the terminal device receives the data of the service according to the configuration information of the wireless resource.

In an exemplary manner, the terminal device receives a fourth notification message from the application server AS, and the fourth notification message is used to notify the terminal device to use a multicast session in the second network to receive service data .

A fifth aspect of the present application provides a method for switching multicast services, including: a target access network device receives seventh indication information from a first session management network element, where the seventh indication information is used to instruct to join the terminal device The multicast session corresponding to the service. The target access network device obtains the parameters of the multicast QoS flow of the multicast session, and allocates wireless resources for the multicast QoS flow according to the seventh indication information and the parameters of the multicast QoS flow. The target access network device sends the configuration information of the wireless resource of the multicast QoS flow to the terminal device through the source access network device, and the source access network device is the terminal device when the terminal device is accessing the terminal device. The access network device that is connected before the target access network device.

Optionally, the seventh indication information and the QoS information of the multicast session are sent by the first session management network element through a message.

A sixth aspect of the present application provides a first session management network element, including: a receiving module, configured to receive first instruction information, where the first instruction information is used to instruct to send to a terminal device located on a first network through a unicast bearer Service data packet; sending module, used to send second instruction information to the first user plane network element, the second instruction information used to instruct to send the data packet to the terminal device through the unicast bearer; join The module is used for adding the terminal device to the multicast session corresponding to the service when the terminal device accesses through the second network.

Optionally, the network element further includes: an obtaining module, configured to obtain multicast quality of service QoS flow information of the service; a first determining module, configured to determine to send the information according to the multicast QoS flow information of the service Unicast bearer of service data packets.

Optionally, the receiving module is specifically configured to: receive a first message, where the first message includes the first indication information and a multicast service identifier of the service; the acquiring module is specifically configured to: according to the The multicast service identifier obtains the multicast QoS flow information of the service.

Optionally, the first indication information includes a multicast service identifier of the service, and the obtaining module is specifically configured to obtain the multicast QoS flow information of the service according to the multicast service identifier.

The first determining module is further configured to: if the first session management network element receives eighth indication information, the eighth indication information indicates that the service supports service continuity, according to the multicast QoS flow The information determines the unicast QoS flow corresponding to the service.

In an exemplary manner, the joining module is specifically configured to: in the process of the terminal device switching from the first network to the second network, transfer the data packets of the service from the unicast The bearer sent to the terminal device is switched to sent to the terminal device via a protocol data unit PDU session, and after the terminal device is switched from the first network to the second network, the terminal device is added to the In a multicast session, the service data packet is switched from being sent to the terminal through the PDU session to being sent to the terminal device through the multicast session.

Optionally, after the terminal device joins the multicast session, the sending module is further configured to: notify the first user plane network element to stop sending the service data to the terminal device through the PDU session .

In another exemplary manner, the joining module is specifically configured to: join the terminal device to the multicast session during the handover process of the terminal device from the first network to the second network, The data packet of the service is switched from being sent to the terminal device via the unicast bearer to being sent to the terminal device via the multicast session.

Optionally, it further includes: a second determining module, configured to determine that the service supports multicast through the second network before the first session management network element joins the terminal device to the multicast session Way to send.

Optionally, the second determining module is specifically configured to: receive a first rule corresponding to the service, the first rule is used for control, policy, or charging, and the first rule includes third indication information The third indication information is used to indicate that the service supports multicast transmission.

Optionally, it further includes a third determining module, configured to determine that the terminal device supports multicast in the second network, and/or the target access network device supports multicast, wherein the terminal device passes all The target access network device accesses the second network.

Optionally, the third determining module is specifically configured to: in the process of establishing a packet data network PDN connection by the terminal device, receive multicast capability indication information sent by the terminal device, and the multicast capability indication information is used for In order to indicate the multicast capability of the terminal device in the second network, it is determined according to the multicast capability indication information that the terminal device supports multicast in the second network.

Optionally, it further includes: an establishment module, configured to trigger the establishment of the multicast session when the multicast session corresponding to the service has not been established.

In an exemplary manner, the joining module is specifically configured to: receive a request message sent by the access and mobility management function AMF, where the request message is used to create or update a PDU session, and the PDU session is related to the service Associate, determine that the service sent through the unicast bearer supports multicast transmission, and the terminal device supports the multicast service in the second network, and instructs the target access network device in the second network Joining the terminal device to the multicast session.

In an exemplary manner, when the terminal device moves into the MBMS area or after it moves into the MBMS area, the receiving module is further configured to: receive fourth indication information, where the fourth indication information is used to instruct to stop passing through the The unicast bearer transmits the data of the service. The sending module is further configured to notify the first user plane network element to stop sending the service data through the unicast bearer according to the fourth instruction information.

Correspondingly, the receiving module is further configured to: after the sending module sends the second indication information to the first user plane network element, receive the second tunnel information from the first user plane network element, and the first The user plane network element receives the data packet of the service from the second user plane network element or the application server through the second tunnel. The sending module is further configured to send the second tunnel information to the second user plane network element or the application server.

In an exemplary manner, after the terminal device is switched to the second network, the sending module is further configured to: send a first notification message to the AS, and the first notification message is used to notify the AS to support Send the data of the service to the terminal device in a multicast manner. Correspondingly, the joining module is specifically configured to: receive fifth instruction information, where the fifth instruction information is used to instruct the terminal device to join the multicast session corresponding to the service, and according to the fifth instruction information, add The terminal joins the multicast session corresponding to the service.

Optionally, before the sending module sends the first notification message to the AS, the receiving module is further configured to: receive sixth indication information, where the sixth indication information is used to indicate when a multicast mode is supported to the terminal When the device sends service data, the first notification message is sent to the AS.

Optionally, it further includes a determining module. Before the joining module joins the terminal to the multicast session corresponding to the service according to the fifth instruction information, the determining module determines that the terminal device is in the second Multicast is supported in the network, and/or the target access network device supports multicast, wherein the terminal device accesses the second network through the target access network device.

The seventh aspect of the present application provides an AS, including: a receiving module, configured to receive a first report from a terminal device, the first report being used to instruct the terminal device to move out of the MBMS area; a determining module, configured to The first report determines that the data packet of the service is sent to the terminal device through the unicast bearer; the sending module is used to send the first indication information to the core network device and/or the first session management network element, the first indication information It is used to instruct to send the data packet of the service to the terminal device through a unicast bearer.

Optionally, the sending module is further configured to: send third indication information to the core network device and/or the first session management network element, where the third indication information is used to indicate that the service supports multicast transmission .

Optionally, the sending module sends third indication information to the core network device, specifically: sending a second message to the core network device, and the second message includes the third indication information and the core network device. The multicast service identifier corresponding to the service.

Optionally, the sending module is further configured to send a multicast service identifier corresponding to the service to the core network device and/or the first session management network element.

Optionally, the sending module is further configured to send the eighth indication information to the core network device and/or the first session management network element, where the eighth indication information indicates that the service supports service continuity.

Optionally, the sending module is further configured to: send sixth indication information to the core network device, where the sixth indication information is used to indicate that when it supports sending service data to the terminal device in a multicast manner, The AS sends the first notification message.

Optionally, the first indication information and the sixth indication information are carried in a first message.

In an exemplary manner, the receiving module is further configured to: receive a first notification message, where the first notification message is used to notify support for using multicast to send the service data to the terminal device, and The sending module is further configured to: in response to the first notification message, send a second notification message to the terminal device, where the second notification message is used to notify the terminal device to use the multicast session to receive the service. data.

In another exemplary manner, the receiving module is further configured to: receive a first notification message, where the first notification message is used to notify that it supports the use of multicast to send the service data to the terminal device, so The sending module is further configured to: in response to the first notification message, send fifth instruction information to the first session management network element or core network device, where the fifth instruction information is used to instruct the terminal device to join The multicast session corresponding to the service.

In an exemplary manner, the receiving module is further configured to: when the terminal device moves from a non-MBMS area into an MBMS area, receive a second report from the terminal device, and the second report is used to notify the The terminal equipment of the AS can receive the data of the service through the MBMS bearer. Correspondingly, the sending module is further configured to send fourth indication information to the core network device, where the fourth indication information is used to instruct to stop sending the data of the service through the unicast bearer.

An eighth aspect of the present application provides a terminal device, including: a sending module, configured to send multicast capability indication information to a first session management network element in the process of establishing a PDN connection for the terminal device, the multicast capability The indication information is used to indicate the multicast capability of the terminal device in the second network; the receiving module is used to receive the target access network device in the second network from the source access network device in the first network The configuration information of the wireless resource allocated to the terminal device, where the configuration information of the wireless resource is used by the terminal device to receive the data of the service in the second network in a multicast manner; the receiving module further It is used to receive the data of the service according to the configuration information of the wireless resource.

In an exemplary manner, the receiving module is further configured to: receive a fourth notification message from the application server AS, where the fourth notification message is used to notify the terminal device to use the multicast session in the second network Receive business data.

A ninth aspect of the present application provides a target access network device, including: a receiving module, configured to receive seventh indication information from a first session management network element, where the seventh indication information is used to instruct to add the terminal device to the service Corresponding multicast session; acquisition module, used to acquire the parameters of the multicast QoS flow of the multicast session; resource allocation module, used to obtain the parameters of the multicast QoS flow according to the seventh indication information and the parameters of the multicast QoS flow The multicast QoS flow allocates wireless resources; a sending module is used to send configuration information of the wireless resources of the multicast QoS flow to the terminal device through a source access network device, and the source access network device is the The access network device that the terminal device accesses before accessing the target access network device.

A tenth aspect of the present application provides a first session management network element, including a processor, a memory, and a transceiver. The memory is used to store instructions, the transceiver is used to communicate with other devices, and the processor is used to execute the The instructions stored in the memory, so that the first session management network element executes the method according to the first aspect or any one of the methods of the present application.

The eleventh aspect of the present application provides an AS, including a processor, a memory, and a transceiver. The memory is used to store instructions, the transceiver is used to communicate with other devices, and the processor is used to execute data stored in the memory. Instructions to make the AS execute the method described in the second aspect or any one of the methods of the present application.

A twelfth aspect of the present application provides a terminal device, including a processor, a memory, and a transceiver. The memory is used to store instructions, the transceiver is used to communicate with other devices, and the processor is used to execute storage in the memory. , So that the terminal device executes the method described in the third aspect or any one of the methods of the present application.

A thirteenth aspect of the present application provides a target access network device, including a processor, a memory, and a transceiver. The memory is used to store instructions, the transceiver is used to communicate with other devices, and the processor is used to execute the The instructions stored in the memory, so that the target access network device executes the method according to the fourth aspect or any one of the methods of the present application.

A fourteenth aspect of the present application provides a computer-readable storage medium, the computer-readable storage medium stores instructions, and when the instructions are executed, the computer executes the first, second, and third aspects of the present application. Aspect, the fourth aspect, or the method of any one of the aspects.

The fifteenth aspect of the present application provides a computer program product. The computer program product includes instructions. When the instructions are executed, the computer executes the first, second, third, and fourth aspects of the present application. Or the method described in either way.

A sixteenth aspect of the present application provides a communication system, including a first session management network element and an AS, where the first session management network element is used to execute the method described in the first aspect or any one of the first aspects of the present application The AS is used to execute the method described in the second aspect or any one of the second aspects of this application.

Optionally, the communication system further includes: a first user plane network element.

In the method and device for switching multicast services provided by the embodiments of the present application, when the signal in the multicast area where the terminal device located in the first network is located is weak, the first session management network element receives the first indication information, and the first indication The information is used to indicate that the service data packet is sent to the terminal device through the unicast bearer. The first session management network element sends second indication information to the first user plane network element. The second indication information is used to indicate the unicast bearer to the terminal device. The terminal device sends a data packet, and when the terminal device accesses through the second network, the first session management network element adds the terminal device to the multicast session corresponding to the service. By first switching the service data from the multicast path of the first network to the unicast bearer of the first network, and then switching from the unicast bearer of the first network to the multicast session of the second network, it is possible to ensure that the terminal equipment is switched from the first network to the multicast session of the second network. During the process of switching from one network to the second network, the multicast service data received by the terminal device through the multicast path of the first network maintains service continuity during the switching process.

Description of the drawings

Figure 1 is a schematic architecture diagram of an LTE system;

Figure 2 is a schematic architecture diagram of a 5G network;

Figure 3 is a schematic diagram of an existing 4G network supporting MBMS;

Figure 4 is a schematic diagram of an existing 5G network supporting multicast mode;

FIG. 5 is a schematic diagram of a network architecture to which an embodiment of the application is applicable;

FIG. 6 is a flowchart of a method for switching a multicast service provided by Embodiment 1 of this application;

FIG. 7 is a flowchart of a method for switching a multicast service provided in Embodiment 2 of the application;

FIG. 8 is a signaling flowchart of a method for switching a multicast service provided in Embodiment 3 of the application;

FIG. 9 is a signaling flowchart of a method for switching a multicast service provided in Embodiment 4 of the application;

FIG. 10 is a signaling flowchart of a method for switching a multicast service provided by Embodiment 5 of the application;

FIG. 11 is a signaling flowchart of a method for switching a multicast service provided by Embodiment 6 of this application;

FIG. 12 is a signaling flowchart of a method for switching a multicast service provided by Embodiment 7 of the application;

FIG. 13 is a signaling flowchart of a method for switching a multicast service provided by Embodiment 8 of this application;

FIG. 14 is a schematic structural diagram of a first session management network element provided by Embodiment 9 of this application;

FIG. 15 is a schematic diagram of the structure of the AS provided in the tenth embodiment of this application;

FIG. 16 is a schematic structural diagram of a terminal device provided in Embodiment 11 of this application;

FIG. 17 is a schematic structural diagram of a target access network device provided in Embodiment 12 of this application;

FIG. 18 is a schematic structural diagram of a first session management network element provided by Embodiment 13 of this application.

Detailed ways

The embodiment of the present application provides a method for switching multicast services, which can realize the multicast service in the process of terminal equipment switching from the fourth-generation mobile communication (4-generation, 4G) system to the fifth-generation mobile communication system Keep business uninterrupted. The 4G network may be an LTE system, and the 5G network is also called a new wireless communication system, a new radio (NR) or a next-generation mobile communication system.

Figure 1 is a schematic architecture diagram of an LTE system. As shown in Figure 1, the LTE system may include: User Equipment (UE), Evolved UMTS Terrestrial Radio Access Network (E-UTRAN), Mobility Management Entity, MME), Serving Gateway (SGW), Packet Data Network Gateway (PGW), Scheme and Charging Rule Function (PCRF), Home Subscriber Server, HSS) and operator’s IP services.

The core network of the LTE network mainly includes three logical functions: MME, SGW, and PGW. MME is a signaling management network element, responsible for non-access stratum (NAS) signaling encryption, and assigning temporary identities to UEs. Identify and select core network equipment such as SGW and PGW, provide roaming, tracking, security and other functions; SGW is the mobility anchor for handover between local evolved NodeB (eNB), and provides legal monitoring related functions. eNB is The base station in the LTE system; PGW is responsible for user address allocation, plan control and charging rules execution, and lawful interception related functions; HSS is used to store user subscription information; PCRF is used to provide plans and charging control rules.

Figure 2 is a schematic architecture diagram of a 5G network. Referring to Figure 2, the access network in the 5G network can be a radio access network (R) AN, and the (R) AN equipment in the 5G network It can be composed of multiple 5G-(R)AN nodes, and the 5G-(R)AN nodes can include: non-3GPP access networks such as access points (APs) of WiFi networks, next-generation base stations (collectively referred to as It is a new generation radio access network node (NG-RAN node), among which the next generation base station includes a new air interface base station (NR nodeB, gNB), a new generation evolved base station (NG-eNB), and a central unit (CU) (GNB, etc., separated from distributed unit (DU)), transmission receiving point (TRP), transmission point (TP) or other nodes.

The 5G core network (5G core/new generation core, 5GC/NGC) includes access and mobility management function (Access and Mobility Management Function, AMF) network elements, session management function (Session Management Function, SMF) network elements, and user plane Function (User Plane Function, UPF) network element, Authentication Server Function (Authentication Server Function, AUSF) network element, Policy Control Function (PCF) network element, Application Function (AF) network element, unified Multiple functional units such as data management function (unified data management, UDM) network elements and network slice selection function (Network Slice Selection Function, NSSF) network elements.

The AMF network element is mainly responsible for services such as mobility management and access management. The SMF network element is mainly responsible for session management, UE address management and allocation, dynamic host configuration protocol functions, selection and control of user plane functions, etc. UPF is mainly responsible for data packet routing and forwarding, message filtering, and execution of quality of service (QoS) control related functions that are connected to the data network (DN) and user plane externally. AUSF is mainly responsible for the authentication function of terminal equipment. The PCF network element is mainly responsible for providing a unified policy framework for network behavior management, providing policy rules for control plane functions, and obtaining registration information related to policy decisions. It should be noted that these functional units can work independently, or can be combined together to achieve certain control functions, such as access control and mobility management functions such as access authentication, security encryption, location registration for terminal equipment, and user Session management functions such as the establishment, release, and modification of the surface transmission path.

The functional units in the 5GC can communicate through the next generation network (NG) interface. For example, the UE can transmit control plane messages with the AMF network element through the NG interface 1 (abbreviated as N1), and the RAN device can communicate through the NG interface. Interface 3 (abbreviated as N3) establishes a user plane data transmission channel with UPF. AN/RAN equipment can establish a control plane signaling connection with AMF network elements through NG interface 2 (abbreviated as N2), and UPF can communicate with UPF via NG interface 4 (abbreviated as N4). SMF network elements exchange information, UPF can exchange user plane data with data network DN through NG interface 6 (abbreviated as N6), AMF network elements can exchange information with SMF network elements through NG interface 11 (abbreviated as N11), SMF network elements can The NG interface 7 (abbreviated as N7) is used for information exchange with the PCF network element, and the AMF network element can perform information exchange with the AUSF through the NG interface 12 (abbreviated as N12). It should be noted that FIG. 2 is only an exemplary architecture diagram. In addition to the functional units shown in FIG. 2, the network architecture may also include other functional units.

UEs in 4G networks and 5G networks are also referred to as terminal devices, mobile stations (mobile stations, MS), mobile terminals (mobile terminals), terminals (terminals), and so on.

The terminal device can communicate with one or more core networks via the RAN. Therefore, the terminal device can also be called a wireless terminal. Handheld device, or other processing device connected to a wireless modem.

For example, the terminal equipment can be a cellular phone, a cordless phone, a session initiation protocol (session initiation protocol, SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), and a wireless Handheld devices, computing devices or other processing devices connected to wireless modems, vehicle-mounted devices or wearable devices with communication functions, virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, industrial control ( Wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical, wireless terminals in smart grid, and transportation safety Wireless terminal, wireless terminal in smart city, wireless terminal in smart home, etc. There is no specific limitation in the embodiments of this application.

In the 4G network, MBMS and eMBMS are introduced for group communication. eMBMS is an evolution of MBMS. MBMS supports two modes of multimedia broadcast service and multicast service. It can broadcast multimedia video information directly to all users or send it to one user. Group subscription subscription users can watch, which can help operators develop a variety of commercial applications such as multimedia advertisements, free and pay TV channels, and MMS group sending. Operators can develop mobile TV services with lower network deployment costs.

In order to realize the multicast service, on the basis of the existing 4G network, functional entities such as Broadcast Multicast Service Center (BM-SC) and MBMS Gateway (MBMS-Gateway, MBMS-GW) are introduced. Figure 3 is a schematic diagram of the existing 4G network architecture that supports MBMS. As shown in Figure 3, the Group Communication Service Application Server (GCS AS) in the application domain provides basic services and supplementary services to the UE , Multimedia conferences, converged communications, SMS gateways, standard attendant consoles and other services.

The GCS AS can send data to the UE in two ways: unicast bearer mode and MBMS bearer mode. Among them, the path corresponding to the unicast bearer (or called the unicast path) is: GCS AS->S/P-GW->E-UTRAN(eNB)->UE, that is, GCS AS sends data to S through the SGi interface /P-GW, S/P-GW means SGW and/or PGW, S/P-GW sends the data to E-UTRAN, and E-UTRAN sends the data to UE. The path corresponding to MBMS bearer is: GCS AS->BM-SC->MBMS-GW->E-UTRAN(eNB)->UE, that is, GCS AS sends data to MBMS-GW, MBMS-GW through MB2-U interface The data is sent to E-UTRAN, and E-UTRAN sends the data to the UE.

To send data through the MBMS bearer, GCS AS first needs to notify the BM-SC to establish a multicast bearer. The process of establishing a multicast bearer will establish an MB2-U interface, and establish a connection from BM-SC to MBMS-GW and from MBMS-GW to E-UTRAN interface, and notify E-UTRAN to establish MBMS air interface bearer. After the MBMS bearer is established, the GCS AS can send the multicast service data to the E-UTRAN through the MBMS bearer and to the UE through the E-UTRAN.

In 4G networks, MBMS has a certain service area, that is, not all base stations support MBMS bearer. If some base stations do not support MBMS bearer, they cannot send multicast service data through MBMS bearer. At this time, in order to ensure service continuity, it will switch to sending data through unicast bearer, that is, through packet data network (Packet Date Network, PDN). ) Connect to send data, that is, send data through S/P-GW.

When the UE is about to or has moved out of the MBMS service area, the UE can send a report to the GCS AS. According to the report, when the GCS AS learns that the UE has moved out or is about to move out of the MBMS service area, it can notify the UE to receive the data of the service through a unicast bearer, and GCS The AS sends the unicast information corresponding to the service (ie group communication service) to the PCRF through the Rx interface, and this process triggers the PGW to modify or create a bearer to prepare resources for sending the unicast data of the service.

Correspondingly, when the UE moves into the MBMS service area, the UE can also send a report to the GCS AS. According to the report, when the GCS AS learns that the UE moves into the MBMS service area, it can notify the UE to receive the data of the service through the MBMS bearer and trigger it through the Rx interface The PGW deletes the unicast bearer resources allocated for the service.

In Figure 3, there is a signaling interface between the UE and the GCS AS, and the signaling between the UE and the GCS AS is also sent through a PDN connection, that is, sent through a unicast bearer. The GSC AS and the BM-SC include an MB2-U interface and an MB2-C interface, where the MB2-U interface is used to transmit multicast service data, and the MB2-C interface is used to transmit signaling related to group communication services.

When the UE is in the 5G coverage area, the UE may also use 5G multicast to receive service data. As shown in Figure 4, when the UE receives service data in a 5G multicast mode, the multicast service data can be sent through the multicast path. For example, the AS (can be GCS AS) sends the multicast service data to the UPF and passes the UPF The shared tunnel with the base station (through which UPF only sends a copy of multicast service data to the base station, and the base station can send the copy of multicast service data to multiple UEs) sends the multicast service data to the 5G base station.

The 5G base station can flexibly determine the playback mode according to the air interface conditions and the number of terminals listening to the service. The playback mode can be a point to multipoint (PTM) mode or a point to point (PTP) mode. Among them, in the PTM mode, the base station sends only one piece of data, which can be received by multiple terminal devices; in the PTP mode, one piece of data sent by the base station can only be received by one terminal device. For the same multicast service, the base station can enable PTM and PTP at the same time, for example, PTM is used for UE1 and UE2, and PTP is used for UE3.

The 5G multicast path includes: AS->UPF->5G AN->UE. There is also a unicast path in the 5G network, that is, the path of a PDU session. The unicast path includes: AS->PGW-U+UPF->5G AN->UE. If there is signaling between the UE and the AS, the signaling can be sent through the unicast path.

The UPF in Figure 4 can be controlled by PGW-C+SMF, or controlled by other SMFs. The UPF and PGW-U+UPF can be the same UPF, or it can be a separate network element. Among them, PGW-U+UPF is a network element with both PGW (PGW-U) and UPF functions with user plane functions. The PGW-U+UPF can be a combined network element with PGW-U and UPF functions. , It can also be composed of two physically independent network elements. Similarly, PGW-C+SMF is a network element with both PGW (PGW-C) and SMF functions with control plane functions. The PGW-C+SMF can be a combined network element with PGW-C and SMF functions. , It can also be composed of two physically independent network elements.

In the existing solutions, the UE can switch between the MBMS bearer and the unicast bearer in the 4G network. Similarly, the UE can also switch between the 5G multicast path and the unicast path in the 5G network. However, when the UE moves from the 4G MBMS area to the coverage area of the 5G base station, how to make the UE switch to the 5G process, the multicast service data received by the UE through the MBMS maintain service continuity during the switch process.

An embodiment of the present application provides a method for switching multicast services, which can ensure that after the UE moves from the MBMS area to the 5G network, the multicast service data received by the UE through the MBMS bearer maintains service continuity during the switching process. Figure 5 is a schematic diagram of the network architecture to which the application method is applicable. As shown in Figure 5, when the 5G network and the 4G network are interoperable, the PGW-C and SMF on the unicast path are co-located, called PGW-C+SMF, PGW -U and UPF are co-located, called PGW-U+UPF. The PCRF in the 4G network is replaced by the PCF, and there is an interface between the PCF and PGW-C+SMF to receive the PCC rules.

In the architecture shown in Figure 5, the path corresponding to the MBMS bearer is the same as the path corresponding to the MBMS bearer in the 4G network shown in Figure 3, and the 5G multicast path shown in Figure 5 is the same as the 5G multicast path in the 5G network shown in Figure 4 .

In a 5G network, in a possible implementation, there is only an interface between a specific UPF and the AS, that is, the AS can only send multicast service data to the specific UPF. In this implementation, the PDU session of the terminal device PGW-U+UPF may not be able to receive multicast service data directly from AS. At this time, if the multicast service data is sent through a PDU session, PGW-U+UPF needs to receive multicast service data from these specific UPFs That is, a path from a specific UPF to PGW-U+UPF needs to be established. In order to support that the multicast service sent through the 5G multicast path can be switched to be sent through the 4G network, in an implementation manner, the embodiment of the application modifies the path corresponding to the unicast bearer of the multicast service on the 4G network. In the 4G network architecture shown in Figure 3, the unicast path of the multicast service in the 4G network is AS (GCS AS)->S/P-GW->eNB->UE. In the system architecture diagram shown in Figure 5 , The unicast path of the multicast service in the 4G network is changed to: AS->UPF->S/P-GW->eNB->UE, that is, in the architecture shown in Figure 5, the multicast service is unicast in the 4G network The path needs to go through UPF. It should be noted that, in the system architecture diagram shown in FIG. 5, the difference from the prior art is that the destination address of the multicast service data packet sent through the 4G unicast path is the multicast address of the multicast service , Not the address of the terminal device.

In addition, in the prior art (ie, the architecture diagram shown in Figure 3), the destination address of the multicast service data sent by the GCS AS through the unicast bearer in the 4G network is the unicast address (that is, the address of the terminal device). The destination address of the multicast service data sent by the MBMS is the multicast address. In the architecture diagram shown in FIG. 5, in a 4G network, the destination addresses of the multicast service data sent by the AS through the unicast bearer or the MBMS bearer are the same, that is, the destination addresses are all the multicast addresses of the multicast service.

In actual deployment, the UPF and PGW-U+UPF shown in Figure 5 may be co-located or not. The embodiment of this application does not limit this. If UPF and PGW-U+UPF are co-located, then There is no such path from UPF to PGW-U+UPF.

In the embodiments of this application, the 4G multicast mode (or 4G multicast path) uses MBMS to carry data, and the 4G unicast mode (or 4G unicast path) uses unicast to transmit data, and the unicast bearer uses PDN. Connect to transmit data. The unicast bearer here refers to the Evolved Packet System bearer (EPS bearer) bearer. The 5G multicast mode uses 5G multicast sessions (or called 5G multicast paths) to transmit data. The data is actually transmitted by the multicast QoS stream in the 5G multicast session. The 5G unicast mode uses PDU session transmission, and the data is actually transmitted by the PDU session. Unicast QoS streaming data.

In addition, the embodiment of the present application takes a multicast service as an example for description, but the method of the embodiment of the present application is also applicable to the broadcast service, and the multicast can be replaced with the broadcast.

Based on the system architecture shown in FIG. 3 or FIG. 5, Embodiment 1 of the present application provides a method for switching multicast services. In this embodiment, the first network is a 4G network and the second network is a 5G network. However, the first The first network and the second network are not limited to 4G networks and 5G networks, and may also be other networks that support multicast services. For example, as the network evolves, the second network may also be a next-generation network. FIG. 6 is a flowchart of a method for switching a multicast service provided in Embodiment 1 of this application. As shown in FIG. 6, the method provided in this embodiment includes the following steps:

S101. The first session management network element receives first indication information, where the first indication information is used to instruct to send a data packet of a service to a terminal device located in a first network through a unicast bearer.

The terminal device currently receives service data in a multicast manner, where the first session management network element may be PGW-C+SMF, and the first indication information is sent to PGW-C after the PCF receives the second message from the AS +SMF, or directly sent by AS to PGW-C+SMF. When the AS learns that the terminal equipment is currently located in the MBMS area of the service in the case of weak signal, or the AS determines that the terminal equipment is about to or has moved out of the MBMS area of the service, the AS directly sends the first message to the PGW-C+SMF One indication information, or after the AS sends the second message to the PCF, the PCF sends the first indication information to the PGW-C+SMF.

The AS can determine that the terminal device is about to or has moved out of the MBMS area of the service by receiving the first report of the terminal device, or knows that the signal of the MBMS area of the service where the terminal device is currently located is weak, where the first report is used to indicate the terminal The device moves out or is about to move out of the MBMS area of the service, or the signal of the MBMS area of the service where the terminal device is currently located is weak.

The first indication information is used to instruct the first session management network element to use unicast bearer to send service data packets to the terminal located in the first network, or to instruct to allocate unicast to the service of the terminal device in the first network Bearer, or, the first indication information is used to instruct to switch or migrate the service of the terminal device from the MBMS bearer to the unicast bearer.

Among them, there are two situations in which service data packets are sent to terminal devices located in the first network through unicast bearer:

Case 1: Based on the architecture of Figure 5, the service data packet sent by the AS includes the service data and the target address, and the target address is the multicast address of the service.

Case 2: Based on the architecture of Figure 5, the service data packet sent by the AS includes the service data and the target address, and the target address is the IP address of the terminal device.

In view of the above situation 1, the first indication information may further include the first rule, or the first indication information is sent to the first session management network element together with the first rule, or the first indication information is the first rule. The first rule can be the policy control and charging (Policy Control and Charging, PCC) rule corresponding to the service when the AS sends the service data in the case 1 mode. Correspondingly, the first indication information is used to indicate the first session The management network element creates a unicast bearer according to the first rule. The first rule is determined by the PCF according to the first description information. The first description information is the corresponding service information when the service is sent in the case one mode, including service identification information and corresponding QoS parameters. The identification information of the service is used to identify the service. For example, it may include any one of the source or destination address, source or destination port number, and protocol number of the data packet of the service.

In a possible method, the first session management network element has acquired the first rule before receiving the first indication information. In this case, the first indication information does not include the first rule, and the first indication information includes The identification information of the service, so that the first session management network element can determine the first rule and/or the second indication information according to the identification information of the service. For a description of the second indication information, refer to S102. The identification information of the service may be the multicast service identification corresponding to the service, or the unicast service identification corresponding to the service, or other information used to identify the service, which is not limited in this implementation.

Further, in this case, the first rule may further include third indication information, and the third indication information is used to indicate that the service supports multicast transmission. Further, the first rule also includes the multicast service identifier corresponding to the service. In an implementation manner, the third indication information is a multicast service identifier corresponding to the service.

In view of the second situation above, the first indication information may further include the second rule, or the first indication information is sent to the first session management network element together with the second rule, or the first indication information is the second rule. The second rule may be the PCC rule corresponding to the service when the AS uses the second method to send the service data. Unlike the first rule, which may include the third indication information, the second rule does not include the third indication information. Yes, the first indication information is used to instruct the first session management network element to create a unicast bearer according to the second rule. The second rule is determined by the PCF according to the second description information. The second description information is the corresponding service information when the service is sent by the second method, including the identification information of the service and the corresponding QoS parameters.

It can be understood that the above case 1 and case 2 are both based on the architecture shown in Figure 5, but there are differences between the two: in case 1, a second tunnel needs to be established between the AS and the first user plane network element, and in case 2, the AS and the first There is no need to establish a second tunnel between a user plane network element.

Optionally, in this embodiment of the present application, after receiving the first indication information, the first session management network element obtains service multicast QoS flow information from UDM or UDR or the second session management network element, according to the multicast QoS of the service The flow information determines the unicast bearer of the sending service. Among them, the first session management network element may obtain the multicast QoS flow information of the service from the UDM or UDR or the second session management network element according to the multicast service identifier, and the multicast service identifier may be the AS or the core network device and the first indication The information is sent to the first session management network element together, or the first indication information includes the multicast service identifier.

The QoS flow information of a service includes the information of one or more QoS flows of the service, and the information of one QoS flow includes the QFI of the QoS flow and the service identification information (for example, five-tuple or service identification, which is mapped to the QoS flow). The destination address in the quintuple information is the multicast IP address of the service), the QoS parameters of the QoS flow (for example, the 5QI corresponding to the QoS flow, the maximum bandwidth requirement, etc.).

Optionally, the first session management network element further receives eighth indication information from the second session management network element or UDM or UDR, where the eighth indication information indicates that the service needs to support service continuity during cross-system handover, Here, business continuity refers to ensuring that the data packets of the business are not lost and/or sent in order when the terminal device is moving. If the first session management network element receives the eighth indication information, it determines the unicast QoS flow corresponding to the service according to the information of the multicast QoS flow.

S102. The first session management network element sends second instruction information to the first user plane network element according to the first instruction information, where the second instruction information is used to instruct to send the service data to the terminal device through the unicast bearer Bag.

Regarding the second case above, the second indication information includes the third mapping relationship between the service identification information and the information of the first tunnel when the AS sends the service data in the second case. Optionally, the service identification information includes the IP address of the terminal device. When the first user plane network element receives the data packet of the service, it determines the information of the first tunnel through which the data packet is sent according to the service identification information of the data packet and the third mapping relationship. Among them, each unicast bearer corresponds to information of a first tunnel, the information of the first tunnel is tunnel information of a downlink node, and the downlink node is an SGW or an access network device (when the SGW is co-located with other network elements).

Regarding the above case 1, the second indication information includes the second mapping relationship between the service identification information and the information of the first tunnel when the AS sends the service data in the case 1, or the identifier QFI of the multicast QoS flow of the service and the first tunnel. The first mapping relationship of information of a tunnel. For the architecture shown in Figure 5, when the unicast path is AS->PGW-U+UPF->eNB->UE, the second indication information includes the second mapping relationship; for the architecture shown in Figure 5, when When the unicast path is AS->UPF->PGW-U+UPF->eNB->UE, the second indication information includes the first mapping relationship, and the first mapping relationship is used by the first user plane network element according to the slave The QFI in the data packet received by the UPF determines the information of the first tunnel used to send the data packet, that is, determines the unicast bearer corresponding to the data packet. Among them, each unicast bearer corresponds to the information of a first tunnel, the information of the first tunnel is the tunnel information of the downlink node, and the downlink node is the SGW or the access network equipment (when the SGW is co-located with other network elements).

When the unicast path is AS->UPF->PGW-U+UPF->eNB->UE, further, the second indication information is also used to obtain the information of the second tunnel, and the information of the second tunnel is used for the first The user plane network element receives the service data packet from the second user plane network element or the application server. As a response message, the first session management network element receives the information of the second tunnel from the first user plane network element, and connects the information of the second tunnel The information is sent to the second user plane network element or AS.

Or, when the unicast path is AS->UPF->PGW-U+UPF->eNB->UE, the second indication information also includes second tunnel information, so that the first user plane network element can receive from the second tunnel After the data packet, the first tunnel information used to send the data packet is determined according to the first mapping relationship.

In addition, the first session management unit also requests other nodes to create unicast bearers. For example, PGW-C+SMF sends a message to SMF to create a unicast bearer. Correspondingly, SGW sends a message to MME, and MME sends a message to access. The network device sends a message to create a unicast bearer. Since the above method is the same as the prior art, it will not be repeated in this embodiment.

For the above situation 1, when the unicast path is AS->PGW-U+UPF->eNB->UE, the second tunnel from AS to PGW-U+UPF needs to be established, then PGW-C+SMF needs further Send the information of the second tunnel to the AS. The PGW-C+SMF may carry the information of the second tunnel in the fifth notification message, and the fifth notification message is used to notify the AS to use the information of the second tunnel to send the data of the service. Further, the fifth notification message is also used to notify that a unicast bearer for sending service data has been established, and the AS may also send a sixth notification message to the terminal device according to the fifth notification message, and the sixth notification message is used for Notify the terminal device to use the unicast bearer to receive the data of the service.

For the above situation 1, when the unicast path is AS->UPF->PGW-U+UPF->eNB->UE, the first session management network element sends the information of the second tunnel to the second user plane network element, Including, if the first session management network element is a session management network element that manages the second user plane network element, the first session management network element directly sends the information of the second tunnel to the second user plane network element; if the first session The management network element is not the session management network element that manages the second user plane network element, then the first session management network element sends the information of the second tunnel to the session management network element that manages the second user plane network element, and the second user plane network element is managed by the second tunnel management network element. The session management network element of the user plane network element sends the information of the second tunnel to the second user plane network element.

S103: When the terminal device accesses through the second network, the first session management network element adds the terminal device to the multicast session corresponding to the service.

It should be noted that, in order to support the switching of the service data sent through the MBMS bearer of the first network to the second network and maintain service continuity, in this embodiment, the terminal device is switched to the second network. Previously, the data of the service was switched from being sent to the terminal device via the MBMS bearer to being sent to the terminal device via the unicast bearer (that is, the EPS bearer). Specifically, it is completed through steps S101 and S102. In order to enable the terminal device to send the first report in time, so as to have enough time to switch the service to the second network after the unicast bearer, the terminal device can be configured with an appropriate MBMS signal strength threshold. When the terminal device detects the MBMS signal When it is lower than the threshold, the terminal device sends the first report.

In this embodiment, the following three service switching methods are provided to implement the switching of multicast services:

The first multicast service switching method: During the switching process of the terminal device from the first network to the second network, the first session management unit switches the data packet of the service from sending to the terminal device via a unicast bearer to passing the PDU The session is sent to the terminal device. After the terminal device is switched from the first network to the second network, the first session management network element adds the terminal device to the multicast session corresponding to the service, and the data packet of the service is sent to The terminal switches to send to the terminal device through the multicast session.

Among them, the PDU session is a unicast path in the second network. Taking the first network as a 4G network and the second network as a 5G network as an example, this method will first switch the data packets transmitted through the MBMS bearer from the MBMS bearer to the 4G network. The unicast path is switched from the unicast path of the 4G network to the unicast path of the 5G network, and then from the unicast path of the 5G network to the multicast path of the 5G network, so as to ensure that the service of the terminal equipment is carried by the MBMS of the 4G network The continuity of the multicast service during the switching process from the transmission to the multicast session transmission through the 5G network. For switching from the unicast path of the 4G network to the unicast path of the 5G network, please refer to the description of the 4G to 5G switching process in the prior art, which will not be repeated here.

5G multicast sessions include 5G multicast paths. 5G multicast sessions can also include one or more QoS streams. Different QoS streams are used to send service data with different QoS requirements. Of course, 5G multicast sessions can also include each QoS. Information such as QoS parameters corresponding to the flow is not limited.

The second multicast service switching method: during the switching of the terminal device from the first network to the second network, the first session management network element adds the terminal device to the multicast session corresponding to the service, and the data packets of the service pass through the The unicast bearer of the first network is sent to the terminal device and is switched to be sent to the terminal device through the multicast session.

Compared with the first switching method, the second switching method directly switches the data packet of the service from the unicast bearer of the first network to the multicast session of the second network by the first session management network element. The unicast bearer of the network is switched to the unicast bearer of the second network, and then the unicast bearer of the second network is switched to the multicast session of the second network.

Both of the foregoing two switching methods can ensure the continuity of the multicast service during the switching process of the terminal device from the first network to the second network.

Before the first session management network element joins the terminal device to the multicast session, the first session management network element also needs to determine whether the service supports multicast transmission through the second network, and whether the terminal device supports grouping in the second network. broadcast. When the service supports multicast transmission through the second network, and the terminal device supports multicast in the second network, the first session management network element adds the terminal device to the multicast session of the service in the second network .

The first session management network element can determine whether the service supports multicast transmission through the second network in the following manner: the first session management network element receives the third indication information, and the third indication information is used to indicate that the service supports the multicast mode send. Further, the third indication information further includes the multicast service identifier of the service, or the third indication information is the multicast service identifier.

In an implementation manner, the foregoing first rule includes third indication information.

Taking the first rule as the PCC rule as an example, the PCF sends the first rule to the first session management network element. The third indication information can be explicitly or implicitly indicated that the service supports multicast transmission of the second network. In the explicit way, the third indication information is a newly added indication in the PCC rules. For example, the PCF can be The PCC rule corresponding to each service adds an indication of whether to support multicast sending, or the PCF adds an indication of multicast sending to the PCC rule corresponding to the service supporting the multicast service. Optionally, if the service supports multicast transmission, the PCC rule also includes a multicast service identifier. For example, the multicast service identifier may be the temporary mobile group identity (TMGI) of the service or the multicast address used to identify the multicast service when the service is played in multicast in the second network. The logo is not limited.

In the implicit method, the multicast service identifier can be used to indicate whether the service supports multicast transmission. When the service’s multicast service identifier is included in the PCC rules of the service, the first session management network element determines that the service supports multicast transmission. . Or, when the destination address of the service included in the PCC rule is a multicast address, it is determined that the service supports multicast transmission.

Optionally, the third indication information may not be carried in the PCC rules, but directly sent by the AS to the PGW-C+SMF, and the AS may carry the third indication information in the service information and send it to the PGW-C+SMF, The service information may include service description information (for example, five-tuple information such as IP address, port number, and protocol number) and QoS requirement information (for example, bandwidth requirement, delay requirement, etc.).

In an implementation manner, the first indication information and the first rule may be carried in the same message and sent to the first session management network element, or the first rule may also be used as the first indication information, that is, the first rule Instructs to send a data packet of a service to a terminal device located in the first network through a unicast bearer.

In another implementation manner, the first indication information and the first rule are carried in different messages, and the first session management network element may receive the first rule before receiving the first indication information. In this implementation manner, the first indication information includes identification information of the service, and the identification information of the service may be a multicast service identification corresponding to the service. The first session management network element may obtain the first rule during the establishment of the PDN connection, or when it sends the data of the service to the terminal device in the unicast bearer mode of the first network for the first time. For example, at the above timing, the AS Send the service information to the PCF. The service information includes the indication information used to indicate whether the service supports multicast transmission and the information when the service is sent in case 1 (the destination address of the data packet is the multicast address) Descriptive information, where the descriptive information includes identification information of at least one data service flow of the service in case one and its corresponding QoS requirement information, and the PCF generates the first rule according to the service information and sends it to the first session management network element.

Further, the first session management network element may determine that the terminal device supports multicast in the second network in the following manner:

The first session management network element may receive the multicast capability indication information sent by the terminal device during the process of establishing the PDN connection of the terminal device, where the multicast capability indication information is used to indicate the multicast capability of the terminal device in the second network. A session management network element determines, according to the multicast capability indication information, that the terminal device supports multicast in the second network.

Exemplarily, the capability indication information is included in the session management capability information of the terminal device. The terminal device can indicate whether the terminal device supports the multicast service through one or more bits of indication information. For example, the terminal device indicates whether the terminal device supports the multicast service through a bit of indication information. When the value of this bit is 1, it indicates that the terminal device supports the multicast service in the second network. When the value is 0, it indicates that the terminal device does not support the multicast service in the second network.

Or, when the terminal device does not support the multicast service in the second network, the terminal device does not carry the multicast capability indication information during the process of establishing the PDN connection. During the process of establishing the PDN connection of the terminal device, the first session management unit determines that the terminal device does not support the multicast service in the second network if the multicast capability indication information is not received, and if the multicast capability indication information is received , It is determined that the terminal device supports the multicast service in the second network.

After the first session management network element determines that the terminal device is added to the multicast session corresponding to the service, the multicast session may or may not have been established. If the multicast session is not established, the first session management network element triggers the establishment of the multicast session. For triggering the establishment of a multicast session by the first session management network element, reference may be made to the description of the prior art, which is not repeated in this embodiment.

In one implementation, the first session management network element receives a request message sent by the AMF. The request message is used to create or update a PDU session. The first session management network element determines that the service sent via a unicast bearer supports multicast transmission. , And the terminal device supports the multicast service in the second network, the first session management network element instructs the target access network device in the second network to add the terminal device to the multicast session.

Exemplarily, the request message is a session creation request message or an update session request message. In the foregoing first multicast service switching method, the request message may be an update session request message, and the request message indicates that the switching is complete, and the first session management network element indicates the target in the second network after receiving the request message The access network device adds the terminal device to the multicast session, that is, the first session management network element instructs the target access network device in the second network to add the terminal device to the multicast session after the handover is completed.

In the foregoing second multicast service switching method, the request message may be a session creation request message, and the request message may indicate handover preparation. The first session management network element instructs the target access network device in the second network to set the terminal The message for the device to join the multicast session is included in the HO request message and sent to the target access network device, that is, the first session management network element instructs the target access network device in the second network to set The terminal device joins the multicast session. The handover request message includes seventh indication information. The seventh indication information is used to instruct the terminal device to join the multicast session corresponding to the service. After receiving the handover request message, the target access network device will perform the The seventh indication information of the terminal device allocates wireless resources for receiving the data of the service through the multicast session, and encapsulates the wireless resources in a transparent container, and sends it to the source access network device in the first network. The access network device sends the wireless resource to the terminal device so that the terminal device can receive service data from the target access network device according to the wireless resource.

Taking the first session management network element as PGW-C+SMF, the first network is a 4G network, and the second network is a 5G network as an example, PGW-C+SMF also obtains the group when the service is sent by multicast in 5G Broadcast the parameters of the QoS flow, in the process of instructing the target access network device in the second network to join the terminal device to the multicast session, or instructing the target access network device in the second network to add the terminal device to the group Before the session is broadcast, the parameters of the multicast QoS flow are sent to the target access network device.

For the first multicast service switching method, after the terminal device joins the multicast session, the first session management network element notifies the first user plane network element to stop sending data of the service to the terminal device through the PDU session.

Regarding the foregoing first or second multicast service switching method, after the terminal device joins the multicast session, optionally, the first session management network element sends a third notification message to the AS to notify the terminal device that the terminal device has switched to The second network is, alternatively, used to notify the AS to use the multicast session to send the data of the service to the terminal device. After the AS receives the third notification message, optionally, in response to the third notification message, the AS sends a fourth notification message to the terminal device, where the fourth notification message is used to notify the terminal device to start using the multicast session to receive service data.

In the third multicast service switching method, the process of switching the data of the multicast service from the MBMS bearer to the unicast bearer is the same as the prior art, or the process of establishing the unicast bearer by the first session management network element is the same as the prior art. The same, and the difference from the prior art is that when the first session management network element receives the indication information sent by the AMF indicating the handover preparation or handover completion, it sends a first notification message to the AS. The first notification message is used to notify the support or the upcoming Support to send the service data to the terminal device in the second network multicast mode, or to notify the terminal device to switch to or about to switch to the second network, or to notify the AS using the method to send to the terminal device The data of the business.

Optionally, before the first session management network element sends the first notification message to the AS, the first session management network element receives sixth indication information, where the sixth indication information is used to indicate when the second network is supported or will be supported. When sending service data to a terminal device in a multicast mode, or when the terminal device switches to or is about to switch to the second network, the first notification message is sent to the AS. Correspondingly, the first session management network element sends the first notification message to the AS when the terminal device starts to switch to the second network or successfully switches to the second network according to the sixth indication information.

The sixth indication information may be sent to the first session management network element together with the first indication information. For example, the first session management network element receives the first message sent by the AS or the PCF, and the first message includes the first message. One instruction information and the sixth instruction information.

It should be noted that in the third multicast service switching method, when the terminal device receives the data of the multicast service through the unicast bearer of the first network, the AS sends the data of the multicast service in the second way (that is, the destination address). Is the address of the terminal device). Therefore, in this manner, the first indication information is the second rule, and the third indication information is not included in the second rule. The sixth indication information and the first indication information are sent together. It can be understood that the second rule includes the sixth indication information, where the sixth indication information may be a subscription request.

In the third multicast service switching method, the first session management network element adds the terminal device to the multicast session corresponding to the service, which may be: the first session management network element receives the fifth indication information, and the fifth indication information is used for After instructing to add the terminal device to the multicast session corresponding to the service, the first session management network element adds the terminal device to the multicast session corresponding to the service according to the fifth instruction information.

The fifth indication information may be sent by the core network device or the terminal device to the first session management network element. After receiving the first notification message, the AS may send a request message for adding the terminal device to the multicast session to the core network device, and the core network device sends the fifth indication information to the first session management network element according to the request message. Alternatively, the AS sends a second notification message to the terminal device after receiving the first notification message, the second notification message is used to notify the terminal device to use the multicast session to receive the data of the service, and in response to the second notification message, the terminal device The first session management network element sends the fifth indication information.

Similar to the first or second multicast service switching method, the first session management network element also needs to determine whether the terminal device supports multicast in the second network. For details, please refer to the first or second multicast service switching Description of the method.

In the third multicast service switching method, the method for the first session management network element to join the terminal device to the multicast session can be referred to the first or second multicast service switching method, which will not be repeated here.

It should be noted that in the third multicast service switching method, before the terminal device switches to the second network, the service is sent to the terminal device through the unicast bearer of the first network. After switching to the second network, the service is sent to the terminal device. The service is switched to the unicast bearer of the second network and sent to the terminal device. The first session management network element may delete the unicast resource corresponding to the service after adding the terminal device to the multicast session. The first session management network element may delete the corresponding unicast resource after receiving the instruction to delete the second rule. In one implementation, the AS sends the delete second description information to the core network device after receiving the first notification message The second description information is the service information when the AS sends the service data in the second case, including the identification information and QoS parameters of the service. The core network device gives the first session when the request to delete the second description information is received The management network element sends an instruction to delete the second rule, where the second rule is generated by the core network device according to the second description information.

In this embodiment, when the signal in the multicast area where the terminal device located in the first network is located is weak, the first session management network element receives first indication information. The terminal device sends a service data packet, and the first session management network element sends second indication information to the first user plane network element. The second indication information is used to indicate that the data packet is sent to the terminal device through a unicast bearer. When the second network is accessed, the first session management network element adds the terminal device to the multicast session corresponding to the service. By first switching the service data from the multicast path of the first network to the unicast bearer of the first network, and then from the unicast bearer of the first network to the unicast path of the second network, then switch to the multicast session, Or, directly switch the service data from the unicast path of the first network to the multicast session of the second network, or switch the service data from the unicast path of the first network to the unicast path of the second network. During the process or after the handover is completed, the first session management network element notifies the AS so that the AS directly notifies the core network device, or the AS notifies the first session management network element through the terminal device to add the terminal to the multicast session of the second network. Therefore, it can be ensured that when the terminal device is switched from the first network to the second network, the multicast service data received by the terminal device through the multicast path of the first network is received through the multicast path of the second network after being switched to the second network. , And maintain business continuity.

FIG. 7 is a flowchart of a method for switching a multicast service provided in Embodiment 2 of this application. Embodiment 1 describes the method from the side of the first session management network element, and this embodiment describes the method from the AS side, as shown in FIG. 7 , The method provided in this embodiment includes the following steps:

S201. The AS receives a first report from a terminal device, where the first report is used to instruct the terminal device to move out of the MBMS area.

The terminal device may send the first report when the signal of the current MBMS area is weak, or when the terminal device is about to or has moved from the MBMS area to the 5G network. In order to support the smooth switching of the data sent through the MBMS bearer to the multicast path in the second network, in this embodiment, it is assumed that the terminal device is configured with an appropriate predetermined value, for example, when the signal quality of the MBMS detected by the terminal device is worse than the predetermined value. When the value is set, the terminal device sends the first report to the AS. The first report is used to instruct the terminal device to move out of the MBMS area, and the MBMS area is the area in the first network.

The network can configure an appropriate predetermined value to ensure that the terminal device sends the first report to the AS before the cell handover from the first network to the second network occurs.

S202. The AS determines, according to the first report, to send the data packet of the service to the terminal device through the unicast bearer.

When the AS learns that the signal of the MBMS area where the terminal device is currently located is weak according to the first report, or the AS determines that the terminal device is about to or has moved out of the MBMS area according to the first report, it determines the unicast via the first network The bearer sends service data packets to the terminal device.

S203. The AS sends first indication information to the core network device and/or the first session management network element, where the first indication information is used to instruct to send a data packet of the service to the terminal device through a unicast bearer.

The first session management network element may be PGW-C+SMF. The AS may directly send the first indication information to PGW-C+SMF, or it may send the first indication information to the core network device, and the core network device sends the first indication information to the core network device. An instruction message is sent to PGW-C+SMF, and the core network device can be PCF or NEF.

Optionally, the AS further sends third indication information to the core network device, where the third indication information is used to indicate that the service supports multicast transmission.

Among them, the AS sends service data packets to the terminal device located in the first network through the unicast bearer of the first network, and there are two situations:

Case 1: The service data packet sent by the AS includes the service data and the target address, and the target address is a multicast address.

Case 2: The service data packet sent by the AS includes the service data and the target address, and the target address is the IP address of the terminal device.

In view of the above situation 1, the first indication information may further include the first rule, or the first indication information is sent to the first session management network element together with the first rule, or the first indication information is the first rule. The first rule may be the PCC rule corresponding to the service when the AS sends the service data in the case one mode. The first rule is determined by the PCF according to the first description information. The first description information is the corresponding service information when the service is sent in the case one mode, including service identification information and corresponding QoS parameters. The first indication information is used to instruct the first session management network element to create a unicast bearer according to the first rule. Optionally, the first indication information includes a multicast service identifier.

Further, in this case, the first rule may also include third indication information. The third indication information is used to indicate that the service supports multicast transmission. When the first indication information does not include a multicast service identifier, the third indication information is used to indicate that the service supports multicast transmission. The third indication information may be a multicast service identifier corresponding to the service. Alternatively, in addition to the third indication information, the first rule also includes the multicast service identifier corresponding to the service, that is, the multicast service identifier exists independently of the first indication information and the third indication information.

In view of the second situation above, the first indication information may further include the second rule, or the first indication information and the second rule are sent to the first session management network element together, and the first indication information of the latter is the second rule. The second rule may be the PCC rule corresponding to the service when the AS sends the service data in the second case. The first indication information is used to instruct the first session management network element to create a unicast bearer according to the second rule. The second rule is determined by the PCF according to the second description information. The second description information is the corresponding service information when the service is sent by the second method, including the identification information of the service and the corresponding QoS parameters.

In one way, after receiving the first report, the AS sends a second message to the PCF or NEF. The second message carries the first indication information. The PCF or NEF carries the first indication information in the first message and sends it to the PGW- C+SMF. The first rule is sent to the PCF, NEF, or PGW-C+SMF before sending the first instruction information. Optionally, the first indication information includes the multicast service identifier, or the second message carries the first indication information and the multicast service identifier. When the second message carries the first indication information and the multicast service identifier, correspondingly, the PCF or NEF carries the first indication information and the multicast service identifier in the first message and sends it to the PGW-C+SMF.

In another way, after receiving the first report, the AS sends a second message to the PCF or NEF. The second message carries the first indication information and the first description information. The PCF or NEF combines the first indication information and the first rule It is carried in the first message and sent to PGW-C+SMF. In this case, the first rule may be used as the first indication information, that is, only the first rule may be included in the first message. Optionally, the first indication information includes the multicast service identifier, or the second message carries the first indication information, the multicast service identifier, and the first description information, or the multicast service identifier may be carried in the first description information middle. When the second message carries the first indication information, the multicast service identifier, and the first description information, correspondingly, the PCF or NEF carries the first indication information, the first rule, and the multicast service identifier in the first message and sends it to PGW-C+SMF, or the multicast service identifier is included in the first rule.

In response to the second situation above, when the first session management network element determines that the terminal device is ready to switch to the second network or the switch is completed, it sends a first notification message to the AS. The first notification message is used to notify that it supports or will support the second network. The multicast method sends the service data to the terminal device, or is used to notify the terminal device to switch to or is about to switch to the second network, or the method is used to notify the AS usage status to send the service data to the terminal device.

Correspondingly, the AS receives the first notification message from the first session management network element, and the AS sends a request message to the core network device for adding the terminal device to the multicast session according to the first notification message, and the core network device sends the request message to the core network device according to the request message. The first session management network element sends the fifth indication information, and the AS may also send the fifth indication information to the core network device. Alternatively, the AS sends a second notification message to the terminal device according to the first notification message. The second notification message is used to notify the terminal device to use the multicast session to receive the data of the service. A session management network element sends fifth indication information.

Optionally, the AS sends sixth indication information to the core network device, where the sixth indication information is used to indicate when it supports or is about to support sending service data to the terminal device in the multicast mode of the second network, or the terminal When the device switches to or is about to switch to the second network, the first notification message is sent to the AS. The AS may send the first indication information and the sixth indication information to the core network device through the second message.

Optionally, after establishing the unicast bearer for the terminal device, the AS receives a fifth notification message from the first session management network element, where the fifth notification message is used to notify the AS to use the unicast bearer of the first network to send data of the service. The AS sends a sixth notification message to the terminal device according to the fifth notification message, where the sixth notification message is used to notify the terminal device to use the unicast bearer of the first network to receive the data of the service.

In this embodiment, the AS receives the first report from the terminal device. The first report is used to instruct the terminal device to move out of the MBMS area. According to the first report, the AS determines to send service data packets to the terminal device through the unicast bearer of the first network. , The parallel core network device and/or the first session management network element sends the first indication information indicating that the data packet of the service is sent to the terminal device through the unicast bearer of the first network. Thus, the first session management network element establishes a unicast bearer of the first network for the terminal device, first switches the data packets of the service to the unicast bearer in the first network, and then switches from the unicast bearer to the second network In this way, it is ensured that when the terminal device switches from the first network to the second network, the multicast service data received by the terminal device through the MBMS bearer maintains service continuity during the switching process.

On the basis of Embodiment 1 and Embodiment 2, FIG. 8 is a signaling flowchart of the method for switching multicast services provided in Embodiment 3 of this application. This embodiment takes the above-mentioned first multicast service switching method as an example. Note that the data transmitted by the MBMS bearer is first switched from the MBMS bearer to the unicast bearer in the 4G network. During the switching process of the terminal device from the 4G network to the 5G network, PGW-C+SMF transfers the data transmitted by the MBMS bearer from 4G The unicast bearer in the network is switched to the PDU session (that is, the unicast path in the 5G network). After the terminal device is switched from the 4G network to the 5G network, PGW-C+SMF will join the terminal device to the 5G multicast session, that is, from 5G The unicast path in the network is switched to the 5G multicast path.

In this embodiment, the AS can directly send the data to PGW-U+UPF, or the AS first sends the data to the UPF, and then sends the data to the PGW-U+UPF through the UPF.

5 and 8, the method provided in this embodiment includes the following steps:

S301. Establish a PDN connection.

The terminal equipment establishes a PDN connection in the 4G network. After the PDN connection is established, the terminal equipment can establish a signaling connection with the AS through the PDN connection. The signaling path is: AS<->PGW-U<->eNB<-> UE and eNB are access network equipment in the 4G network. Moreover, if the current location of the terminal device supports MBMS, the AS can notify the terminal device to receive service data (for example, media data) through the MBMS bearer. The path for AS to send data to the terminal device through the MBMS bearer is: AS->BM-SC->MBMS GW->eNB->UE.

The process of establishing a PDN connection can refer to the prior art, which will not be repeated here. Different from the prior art, if the terminal device supports 5G multicast capability, the terminal device carries 5G multicast capability indication information in the protocol configuration option (Protocol Configuration Option, PCO) of the PDN connection establishment request message.

In order to support 4G and 5G intercommunication, the PGW-C selected by the MME for the PDN connection is PGW-C+SMF, and the UPF selected by the PGW-C+SMF for the PDN connection is PGW-U+UPF.

The data between AS and terminal equipment is divided into two categories, one is signaling data stream, and the other is non-signaling data stream (such as voice or video or file data). AS can determine which data streams are sent by MBMS bearer and which data are in Sent via unicast bearer. For example, the signaling data stream is sent through the unicast bearer, and the non-signaling data stream is sent through the MBMS bearer. Of course, the AS can also decide to send part of the signaling data stream through the MBMS bearer and the other part of the signaling data stream through the unicast bearer. .

For service data streams that will not be sent via the MBMS bearer, the AS can use the IP address (unicast address) of the terminal device to send these service data streams. For service data streams that may be sent via MBMS bearer, AS can use multicast IP addresses to send. It should be noted that the service data stream that may be sent through the MBMS bearer can also be sent through the unicast bearer when the UE moves out of the MBMS area. If the destination address of the service data packet sent on the MBMS bearer is a multicast IP address, after the service data packet is switched to be sent via the unicast bearer, the AS does not need to change the format of these data packets, that is, the destination IP address can still be used Use multicast IP address.

Optionally, the AS may establish a policy session to a core network device (such as PCF/NEF), and the policy session is associated with the PDN connection. The AS can send the description information of the service to the core network device through the policy session, so that the mobile network can allocate corresponding unicast bearer resources for the service. The description information of the service sent to the core network includes identification information of the service (for example, five-tuple information such as IP address, port number, protocol number, etc.) and QoS requirement information (for example, bandwidth requirement, delay requirement, etc.). It should be noted that the service may include at least one service data stream, and the description information of the service includes the description information of at least one service data stream.

If the AS supports sending the service via multicast (5G multicast or MBMS multicast), the AS includes third indication information in the description information of the service, and the third indication information is used to indicate that the service supports multicast sending .

Optionally, even if the service supporting the multicast mode is currently sent via the MBMS bearer, the AS may send the description information of the service to the core network device in advance. When sending the description information of the service, the AS indicates that the service is not currently sent through a unicast bearer (or is currently sent through an MBMS bearer).

This step can also create an interface between AS and PGW-U+UPF for services that support multicast transmission. Of course, the interface can also be created in step S305. Specifically, the AS can send the processing requirements of the multicast service to the core network equipment. For example, the AS can request the core network to perform robust header compression (ROHC) or forward error correction (Forward Error Correction) on service data. , FEC) coding, etc. The AS may include the above processing requirements in the information of the business.

The PCF can generate a PCC rule (first rule) according to the description information of the service sent by the AS and the aforementioned processing requirements, and send the PCC rule to the PGW-C+SMF corresponding to the PDN connection. If the AS indicates that the service supports multicast transmission, the PCF also sends the indication information to PGW-C+SMF, so that PGW-C+SMF learns that the service supports multicast transmission. For example, the PCF may carry third indication information in the PCC rule, and the third indication information is used to indicate whether multicast transmission is supported. If the AS sends the above processing requirement to the PCF, the PCF also sends the processing requirement to PGW-C+SMF. For example, the PCC rule carries the processing requirement. If the service information sent by the AS includes the multicast service identifier, the PCF sends the multicast service identifier to the PGW-C+SMF. For example, the PCC rule includes the multicast service identifier.

Wherein, in this embodiment, when the AS sends a service data packet to a terminal device located in the first network through a unicast bearer, the service data packet sent by the AS includes the service data and the target address, and the target address is the group Broadcast address.

If the transmission path between PGW-U+UPF and AS or UPF has not been established, PGW-C+SMF informs PGW-U+UPF to establish the path. Specifically, for the second tunnel between PGW-U+UPF and AS, if the path is based on the MB2-U interface, then PGW-C+SMF can be allocated or PGW-C+SMF requests PGW-U+UPF to allocate MB2-U Interface information, MB2-U interface information includes the User Datagram Protocol (UDP) port number and IP address used to receive the service data.

The UDP port number + IP address is used to identify the second tunnel between AS and PGW-U+UPF. The service is transmitted between AS and PGW-U+UPF through the second tunnel. The UDP port number + IP address can be It is created for the service, or it may be created for the service of the terminal device. When the information of the MB2-U interface is created for the service, the data of the service on the PGW-U+UPF from the AS can be used to send to multiple terminal devices served by the PGW-U+UPF (ie AS and PGW -The second tunnel between U+UPF is a shared tunnel). If the information of the MB2-U interface is created for the service of the terminal device, the data received by the PGW-U+UPF from the AS can only be sent to the terminal, that is, the second one between the AS and PGW-U+UPF The tunnel is a dedicated tunnel for terminal equipment. The path may also be based on other tunnel technologies, for example, a GTP-U tunnel. The establishment of a GTP-U tunnel is similar to the above-mentioned tunnel, and will not be repeated in this embodiment.

After PGW-C+SMF obtains the information of the second tunnel, PGW-C+SMF sends the information of the second tunnel to the AS, so that the AS sends the service data packet to the PGW through the second tunnel according to the information of the second tunnel -U+UPF. The PGW-C+SMF may carry the information of the second tunnel in the fifth notification message or send it to the AS in other messages. The fifth notification message is used to notify the AS to use the unicast bearer to send the data of the service.

When the AS sends the service data to the UPF first and then the UPF to PGW-U+UPF, the second tunnel between PGW-U+UPF and UPF needs to be established, for the second tunnel between PGW-U+UPF and UPF The second tunnel is based on GTP-U, PGW-C+SMF can request PGW-U+SMF to allocate the tunnel information of the second tunnel, including the tunnel endpoint identifier (Tunnel Endpoint Identifier, TEID) and IP address, and send it to UPF, If the UPF is managed by another SMF, the PGW-C+SMF sends the information of the second tunnel to the SMF and the SMF sends it to the UPF. In this scenario, the UPF maps the service data to the multicast QoS stream and sends it to the PGW-U+UPF through the second tunnel. The SMF managing the UPF can determine at least one multicast QoS flow corresponding to the service according to the first rule of the service, including the QFI of the multicast QoS flow, the data flow of the service mapped to the multicast QoS flow, and the multicast QoS flow. QoS parameters of QoS flow, etc.

S302. The terminal device sends a first report to the AS, where the first report is used to instruct the terminal device to move out of the MBMS area.

It is assumed that in step S301, the terminal device is located in the MBMS area of the service, and the terminal device receives the data of the service through the MBMS bearer. Then, when the terminal device moves out of the MBMS area, the first report is sent to the AS.

The network can configure an appropriate signal predetermined value to ensure that the terminal device sends the first report to the AS before the cell handover from the 4G network to the 5G network occurs, for example, when the terminal device detects that the MBMS signal quality is worse than the signal predetermined value , The terminal device sends the first report to the AS, and reports the event that the MBMS channel quality of the terminal device is worse than the predetermined value of the signal to the AS.

S303. The AS sends a second message to the PCF, where the second message includes the first indication information.

The first indication information is used to indicate that a data packet of a service is sent to a terminal device located in the first network through a unicast bearer. Optionally, the first indication information includes a multicast service identifier. Or, the second message includes the first indication information and the multicast service identifier.

When it needs to be clarified, the service includes multiple service data streams. In one case, all service data streams in the service are currently sent through the MBMS bearer. In another case, part of the service data streams in the service currently pass The MBMS bearer is sent, and another part of the service data stream is currently sent through the unicast bearer. In the embodiment of this application, when the service of the terminal device is switched from the MBMS bearer to the unicast bearer, only the service data stream currently sent through the MBMS bearer is switched to the unicast bearer, and the service data stream currently sent through the unicast bearer is not Do processing.

If the AS has established a policy session associated with the PDN connection (that is, the PDN connection established in S301), the AS sends the second message through the policy session.

If the AS does not send the description information of the service data flow that needs to be switched to the unicast bearer to the PCF/NEF in step S301, the second message may also include the description information of the service data flow that needs to be switched to the unicast bearer. If the AS has already sent the description information of the service data stream that needs to be switched to the unicast bearer to the PCF/NEF in step S301, the second message may include the description information of the service data stream that needs to be switched to the unicast bearer. It may not include the description information of the service data flow that needs to be switched to the unicast bearer.

Wherein, the description information of the service data stream that needs to be switched to the unicast bearer includes third indication information, and the third indication information indicates that these service data streams support multicast transmission (5G multicast or MBMS multicast). Wherein, the third indication information may be indicated in a display manner or an implicit manner, refer to the related description of Embodiment 1, and details are not described herein again.

Optionally, the second message also includes the processing requirements of the AS for these service data streams. For example, the AS may request the core network to perform header compression (ROHC) or forward redundancy coding (FEC) on the service data. Please refer to the description of S301, which will not be repeated here.

S304. The PCF sends a first message to the PGW-C+SMF, where the first message includes the first indication information.

Optionally, the first message includes the PCC rule (ie, the first rule) corresponding to the service data stream that needs to be switched to the unicast bearer to send, and the PCC rule includes the third indication information, and the PCC rule is the PCF according to the second message It is generated by including the description information of the service data flow that needs to be switched to the unicast bearer. Or, if PGW-C+SMF has obtained the PCC rules of these service data streams, the first message may only include the first indication information. Optionally, the first message also includes a multicast service identifier.

Optionally, in other embodiments, the AS may directly send the second message to PGW-C+SMF.

It should be noted that in this embodiment of the application, the first indication information included in the second message sent by the AS to the core network device is the same as the first indication information included in the first message sent by the core network device to the PGW-C+SMF. The indication information has the same function and is used to instruct to send service data packets to the terminal device located in the first network through unicast bearer. However, the names of the two in the first message and the second message can be different. This application is implemented In the example, the indication information in the first message and the second message for instructing to send service data packets to the terminal device located in the first network through unicast bearer is collectively referred to as the first indication message for the convenience of description, but the indication The name of the information in the first message and the second message is not limited.

S305. PGW-C+SMF establishes a unicast bearer for services that support multicast transmission.

If the second tunnel has not been established, the second tunnel is established in this step. For details, refer to the related description in step S301, which will not be repeated here. The establishment of unicast bearer for services that support multicast transmission includes:

PGW-C+SMF establishes a unicast bearer for the service according to the first indication information. During the establishment process, PGW-C+SMF sends second indication information to PGW-U+UPF. The broadcast bearer sends data packets to the terminal device. PGW-U+UPF receives the second indication information. For case 1, if the transmission path between PGW-U+UPF and AS has not been established, follow the steps in S301 to establish a second connection between PGW-U+UPF and AS. tunnel. For the related information of the second indication information, refer to the description of the first embodiment, which will not be repeated here.

If the second tunnel is a tunnel between PGW-U+UPF and AS or PGW-U+UPF directly receives data of the service from AS (ie, no second tunnel is needed), then the second indication information includes the second mapping relationship , The second mapping relationship is the mapping relationship between the service identification information and the information of the first tunnel when the AS sends the service data in the case 1, PGW-U+UPF can be received from the second tunnel or directly from the AS The data packet of the received service is matched with the second mapping relationship, and if the matching is successful, the data packet is sent through the matched first tunnel. PGW-C+SMF can determine the bearer corresponding to each service data flow according to the PCC rules of the service, generate a second mapping relationship based on the identification information of the service data flow and the first tunnel information corresponding to the bearer, and send it to the PGW -U+UPF, so that PGW-U+UPF can determine the bearer tunnel corresponding to the received service data packet. When mapping the service data stream to a unicast bearer, PGW-C+SMF can map the service data stream to a new bearer, that is, create a new bearer for the service data stream, or PGW-C+SMF can also The data flow of the service can be mapped to the existing bearer, that is, the existing bearer can be modified to increase the data flow of the service.

If the second tunnel is a tunnel between PGW-U+UPF and UPF, then PGW-C+SMF determines the first mapping relationship between the QFI of the multicast QoS flow and the first tunnel information, and sends the first mapping relationship to the PGW -U+UPF, so that PGW-U+UPF determines the first tunnel information of the corresponding unicast bearer according to the QFI of the data packet received from the second tunnel, so as to use the first tunnel to send the data packet, that is, the second indication The information includes the first mapping relationship.

Establishing a unicast bearer also includes notifying the SGW, the base station in the first network, etc. to allocate tunnel information for the bearer, and allocating corresponding resources. For details, please refer to the prior art, which will not be repeated here.

In addition, in order for the service to switch from unicast bearer transmission via the first network to PDU session transmission via the second network, in this step, PGW-C+SMF also determines that the service passes through the PDU session of the second network The parameters of the corresponding unicast QoS flow when sending, for example, PGW-C+SMF can map one or more data flows of the service to a unicast QoS flow, and according to the service data mapped to the unicast QoS flow The QoS parameters of the flow determine the QoS parameters of the unicast QoS flow, and send the parameters of the unicast QoS flow to the terminal device. The parameters of the unicast QoS flow include the QFI of the unicast QoS flow.

S306. PGW-C+SMF sends a fifth notification message to the AS.

The fifth notification message is used to notify the AS to use the unicast bearer to send the data of the service, or to notify the AS that the network has switched or migrated the service data stream transmitted on the MBMS bearer to the unicast bearer.

If the information of the second tunnel between the PGW-U+UPF and the AS is allocated in step S305, the PGW-C+SMF includes the information of the second tunnel in the fifth notification message, so that the AS can follow the information of the second tunnel. The information sends business data to PGW-U+UPF.

S307. The AS sends a sixth notification message to the terminal device.

In response to the fifth notification message, the AS sends a sixth notification message to the terminal device. The sixth notification message is used to notify the terminal device to use the unicast bearer to receive the data of the service, or to notify the terminal device that the network has carried the MBMS The service data stream transmitted on the uplink is switched or migrated to the unicast bearer.

Among them, steps S306 and S307 are optional steps, that is, after the PGW-C+SMF establishes the unicast bearer, the AS and the terminal device may not be notified. Or, PGW-C+SMF sends the fifth notification message to the AS, and the AS does not send the sixth notification message to the terminal device.

S308. The terminal device is switched from the 4G network to the 5G network.

The cell handover process refers to the existing technology and will not be repeated here. In this embodiment, during the cell handover process, the service data stream transmitted on the MBMS bearer is switched from the unicast bearer of the 4G network to the unicast path of the 5G network. The unicast path of the network is the PDU session, and the data is carried in the unicast QoS flow in the PDU session.

It can be understood that the data in the 5G network is transmitted through QoS streams. In this embodiment, there are two types of QoS streams: unicast QoS streams and multicast QoS streams. The service data stream transmitted on the MBMS bearer will be mapped to the unicast QoS stream. Or a multicast QoS flow, where the unicast QoS flow is the data carrier in the 5G unicast path, and the multicast QoS flow is the data carrier in the 5G multicast path.

S309. The terminal device is added to the 5G multicast session corresponding to the service.

If the service supports sending via multicast, after the terminal device is successfully switched to the 5G network, the terminal device can be added to the 5G multicast session corresponding to the service. It is understandable that after the terminal device switches to the 5G network, the 5G multicast session may or may not be established. If the 5G multicast session is not established, PGW-C+SMF triggers the establishment of the 5G multicast session, PGW-C+ SMF triggers the establishment of a 5G multicast session, which can be referred to in the prior art, and details are not repeated here.

When the terminal device is successfully switched to the 5G network, PGW-C+SMF determines whether the terminal device supports the 5G multicast service, and if the service supports multicast transmission, then PGW-C+SMF determines to add the terminal device to the corresponding service 5G multicast session.

The PGW-C+SMF can determine whether the terminal device supports the 5G multicast service according to the 5G multicast capability indication information of the terminal device received in step 301.

The PGW-C+SMF can determine whether the service supports multicast transmission according to the third indication information received from the PCF or AS in the foregoing step 301 or 304.

Optionally, the PGW-C+SMF determines that the target base station supports 5G multicast capability before determining to add the terminal device to the 5G multicast session corresponding to the service, and the target base station is the base station that the terminal device accesses in the 5G network. For example, during the handover process, PGW-C+SMF can acquire the 5G multicast capability of the target base station. For example, PGW-C+SMF acquires the capability of the target base station from AMF (the target base station can send this capability when it supports 5G multicast services). To AMF). Alternatively, the PGW-C+SMF acquires the 5G multicast capability of the target base station in the process of triggering the creation of the multicast session to the target base station (if the multicast session is successfully created, it means that the base station supports 5G multicast capability).

Optionally, PGW-C+SMF may not acquire the 5G multicast capability of the target base station during the handover process, but when it is determined that the terminal device supports 5G multicast services and the service supports multicast transmission, Request the target base station to join the terminal device to the 5G multicast session. If the target base station supports 5G multicast services, it agrees to join. If the target base station does not support 5G multicast services, the join fails. PGW-C+SMF determines based on the join failure event. The target base station does not support 5G multicast services.

It can be understood that joining a terminal device to a 5G multicast session needs to be completed jointly by multiple network elements, for example, a base station gNB (that is, a target base station) and PGW-C+SMF in a 5G network are required. PGW-C+SMF can notify the target base station to join the terminal device to the 5G multicast session after the 5G multicast session is established, or PGW-C+SMF can also notify the target base station to join the terminal during the establishment of the 5G multicast session The device joins the 5G multicast session, that is, when sending the parameters of the multicast QoS flow of the service to the target base station, the target base station is notified to add the terminal device to the 5G multicast session. When the target base station receives the request to join the terminal device to the 5G multicast session, it configures the terminal device with corresponding wireless resources to receive the service data corresponding to the 5G multicast session from the target base station.

S310. PGW-C+SMF sends a third notification message to the AS.

In this embodiment, after PGW-C+SMF joins the terminal device to the 5G multicast session corresponding to the service, PGW-C+SMF sends a third notification message to the AS, and the third notification message is used to notify the terminal device Switched to the second network, or used to notify the AS to start using the 5G multicast session to send the data of the service to the terminal device.

S311. The AS sends a fourth notification message to the terminal device.

In response to the third notification message, the AS sends a fourth notification message to the terminal device, where the fourth notification message is used to notify the terminal device to use the 5G multicast session to receive the data of the service.

S312. Delete the unicast QoS flow.

When PGW-C+SMF switches the service data stream of the service to be sent through a 5G multicast session, PGW-C+SMF can delete the radio resources of the unicast QoS stream previously allocated for the service data stream.

Optionally, PGW-C+SMF can retain the context of unicast QoS flows, but PGW-C+SMF requests the gNB to delete the radio resources of these unicast QoS flows to save gNB resources.

Optionally, PGW-C+SMF also informs PGW-U+UPF to stop sending to the terminal device those service data streams that have been migrated to be sent through the 5G multicast session.

FIG. 9 is a signaling flowchart of a method for switching a multicast service provided in Embodiment 4 of this application. The method in this embodiment can be executed before step S308 in Embodiment 3. As shown in FIG. 9, the method provided in this embodiment is It includes the following steps:

S401. Establish a PDN connection.

For the specific implementation of this step, refer to the description of step S301 in the third embodiment, which will not be repeated here. The PDN connection is used to send signaling between the terminal equipment and the AS.

S402: The data of the multicast service is transmitted through the unicast bearer.

Different from the first embodiment, after the PDN connection is established, the multicast service is transmitted through the MBMS bearer. In this embodiment, the multicast service is transmitted through the unicast bearer. For the establishment of the unicast bearer, refer to the steps S301-S307 in the third embodiment. Description, that is, when the terminal device moves out of the MBMS area, the data of these multicast services is migrated to be sent through the unicast bearer.

S403: The terminal device sends a second report to the AS, where the second report is used to notify the AS that the terminal device can receive service data through the MBMS bearer.

When the terminal device moves from the non-MBMS area into the MBMS area, the terminal device detects the MBMS signal and detects that the data corresponding to the service is being sent through the MBMS bearer (the base station will use the TMGI corresponding to the service), the terminal device sends a second report to AS, the AS learns according to the second report that the multicast service data stream of the service can be sent to the terminal device through the MBMS bearer.

S404. The AS sends fourth indication information to the PCF.

The fourth indication information is used to instruct to stop sending the data of the service through the unicast bearer, or to instruct the terminal device to receive the data of the service through the MBMS bearer, or to instruct the core network element to delete the corresponding multicast service Unicast bearer resources.

In an implementation manner, the fourth indication information includes description information of service data streams (that is, multicast service data streams) that need to be deleted from the unicast bearer, so that the PCF deletes the unicast bearer resources corresponding to these service data streams.

In another implementation manner, the fourth indication information does not include the description information of the service data stream that needs to be deleted, but only includes the identification information of the service. The PCF corresponds to the service data stream supporting the multicast mode in the service according to the identification information of the service. The bearer resource is deleted. It should be understood that the AS indicates which service data streams support the multicast mode in step 402, and the PCF can determine which service data streams corresponding unicast bearer resources need to be deleted according to the instructions in step 402.

S405. The PCF sends the fourth indication information to PGW-C+SMF.

Corresponding to the former implementation of S404, the PCF informs PGW-C+SMF to delete the PCC rules corresponding to these service data streams through the fourth instruction information; for the latter implementation, the PCF only informs PGW-C+ through the fourth instruction information The SMF deletes the unicast bearer resources of the service data stream supporting the multicast mode, and the PCC rules are retained.

It should be noted that in the embodiments of this application, for the convenience of description, the instruction information sent by the AS to the core network device for instructing to stop sending the data of the service through the unicast bearer, and the core network device to the PGW-C+SMF The sent instruction information used to instruct to stop sending the data of the service through the unicast bearer is called the fourth instruction information. It can be understood that the name of the instruction information sent in different messages or between different network elements may be different. The embodiment of the present application does not limit the name of the indication information in different messages or the names sent between different network elements.

S406. Delete the unicast bearer resource corresponding to the multicast service.

The PGW-C+SMF deletes the unicast bearer resource created in the foregoing steps. For example, the PGW-C+SMF notifies the SGW, MME, and eNB to delete the resource corresponding to the unicast bearer. For details, please refer to the prior art. In addition, PGW-C+SMF also notifies PGW-U+UPF to stop sending data of the multicast service through the unicast bearer, for example, notifies PGW-U+UPF to delete the first mapping relationship or the second mapping relationship.

For the former implementation in steps S404 and S405, PGW-C+SMF deletes the corresponding PCC rule. For the latter implementation in steps S404 and S405, PGW-C+SMF still retains the corresponding PCC rules.

S407. The AS sends a seventh notification message to the terminal device.

The seventh notification message is used to notify the terminal device to receive corresponding data through the MBMS bearer. In this embodiment, step S407 is executed after step S406. Optionally, in other embodiments of the present application, step S407 may be executed before step S404.

On the basis of Embodiment 1 and Embodiment 2, FIG. 10 is a signaling flowchart of the method for switching multicast services provided in Embodiment 5 of this application. The difference from Embodiment 3 is that this embodiment uses the above-mentioned second type Take the multicast service switching method as an example to illustrate, that is, the data transmitted by the MBMS bearer is first switched from the MBMS bearer to the unicast bearer in the 4G network. During the switching process of the terminal device from the 4G network to the 5G network, PGW-C+ SMF switches the data transmitted by the MBMS bearer from the unicast bearer in the 4G network to the 5G multicast session, that is, there is no need to switch from the unicast bearer in the 4G network to the unicast bearer in the 5G network, thus omitting the 5G network. Establishment of unicast QoS flow. As shown in Figure 10, the method provided in this embodiment includes the following steps:

S501. Establish a PDN connection.

S502: The terminal device sends a first report to the AS, where the first report is used to instruct the terminal device to move out of the MBMS area.

S503. The AS sends a second message to the PCF, where the second message includes the first indication information.

The first indication information is used to indicate that a service data packet is sent to the terminal device via a unicast bearer. Optionally, the first indication information includes a multicast service identifier, or the second message includes the first indication information and multicast Business identity.

S504. The PCF sends a first message to PGW-C+SMF, where the first message includes first indication information.

It should be noted that in the embodiments of this application, for the convenience of description, the instruction information sent by the AS to the core network device for instructing to send the data of the service through the unicast bearer, and the core network device sends to the PGW-C+SMF The instruction information used to instruct to send the data of the service through the unicast bearer is called the first instruction information. It can be understood that the name of the instruction information sent in different messages or between different network elements may be different. This application The embodiment does not limit the names of the indication information in different messages or the names sent between different network elements. Other instructions in this application specification are also similar, and are explained here in a unified manner. Optionally, the first message also includes a multicast service identifier.

S505. PGW-C+SMF establishes a unicast bearer for services that support multicast transmission.

S506. PGW-C+SMF sends a fifth notification message to the AS.

S507. The AS sends a sixth notification message to the terminal device.

For the specific implementation of steps 501-507, refer to the description of steps S301-S307 in the third embodiment, which will not be repeated here. In addition to the description of S301-S307, this embodiment also includes:

Optionally, in step S501 or step S505, PGW-C+SMF also obtains the multicast QoS flow information of the service, and sends the parameters of the multicast QoS flow to the terminal device, where the parameters of the multicast QoS flow include each The QFI of the multicast QoS stream, and optional QoS parameters, etc. Sending the parameters of the multicast QoS stream to the terminal device is used to receive service data according to the parameters of the multicast QoS stream after the terminal is added to the multicast session of the second network.

S508: The eNB sends a first handover request to the MME.

The eNB is a base station in the 4G network, also referred to as the source base station, and the first handover request is used to request handover to the target base station in the 5G network, that is, the gNB.

S509. The MME sends a first handover request to the AMF.

The MME may forward the first handover request to the AMF through a Forward Relocation Request (Forward Relocation Request) message.

S510. The AMF sends a create session request (Create SM Context Request) to the PGW-C+SMF.

For the specific implementation of S508-S510, refer to the prior art, which will not be repeated here.

S511. Create a 5G multicast session corresponding to the service.

If the multicast session corresponding to the service has not been established, the create session request message is used to trigger the creation of the 5G multicast session of the service. After receiving the create session request message, PGW-C+SMF determines according to the context of the session The PDN connection includes support for services sent through 5G multicast. For example, if the PCC rule of the service associated with the PDN connection includes the third indication information, the service supports 5G multicast transmission. It should be understood that the service data streams that support multicast transmission on the PDN connection may correspond to different 5G multicast sessions. PGW-C+SMF determines whether these service data streams belong to the same 5G group according to the PCC rules corresponding to these service data streams. Broadcast session.

The establishment of a 5G multicast session refers to related descriptions in the prior art, and details are not described herein again. The establishment of a 5G multicast session includes: sending the parameters of the multicast QoS stream to the target base station, so that the target base station creates a corresponding context, and establishes the first tunnel from the UPF (the UPF can be PGW-U+UPF) to the target base station, The first tunnel is used for UPF to send multicast service data.

S512. The PGW-C+SMF sends a session creation request response to the AMF.

After the 5G multicast session is established, PGW-C+SMF sends a session creation request response to AMF. The session creation request response includes a message sent to the target base station in the 5G network, and the message sent to the target base station includes the seventh Indication information, the seventh indication information is used to instruct the terminal device to join the multicast session corresponding to the service, that is, the 5G multicast session.

Optionally, the session creation request response further includes parameters of the multicast QoS flow of the 5G multicast session sent to the target base station.

Optionally, the parameters of the multicast QoS stream may also be sent in step S511, that is, during the establishment of the 5G multicast session, the PGW-C+SMF sends the parameters of the multicast QoS stream to the target base station.

S513. The AMF sends a second handover request to the gNB.

gNB is the target base station. AMF carries the seventh indication information received from PGW-C+SMF in the second handover request and sends it to gNB. If the session creation request response includes the parameters of the multicast QoS flow, the second handover request Include the parameters of the multicast QoS flow. The gNB allocates wireless resources for the multicast QoS flow according to the seventh indication information and the parameters of the multicast QoS flow.

S514. The gNB sends a second handover request response to the AMF.

The second handover request response includes a transparent container, and the transparent container includes configuration information of the wireless resource of the multicast QoS flow allocated by the gNB for the terminal device to join the 5G multicast session.

S515. The AMF sends the second handover request response to the eNB through the MME.

S516. The eNB sends a handover command to the terminal device.

The eNB obtains the configuration information of the wireless resources allocated by the gNB for the multicast QoS flow of the terminal device from the transparent container, carries the configuration information of the wireless resource allocated by the multicast QoS flow in the handover command and sends it to the terminal device.

The terminal device is configured according to the configuration information of the wireless resource allocated by the multicast QoS flow, and accesses the gNB. After the configuration is completed, the data of the multicast service can be transmitted through the 5G multicast session.

In S514 to S516, the target base station sends the wireless resource configuration information of the multicast QoS stream to the terminal device through the source base station.

S517. Subsequent switching process.

The subsequent handover process includes that after the terminal device accesses the gNB, the gNB sends a notification to the AMF, and the AMF notifies the PGW-C+SMF switching path. This embodiment does not modify the subsequent handover process compared to the prior art.

S518. PGW-C+SMF sends a third notification message to the AS.

S519. The AS sends a sixth notification message to the terminal device.

For the specific implementation of S518 and S519, reference may be made to the related description of steps S310 and S311 in the third embodiment, which will not be repeated here.

Compared with the third embodiment, the data transmitted by the MBMS bearer in this embodiment is directly switched from the unicast bearer in the 4G network to the 5G multicast session, that is, there is no need to switch from the unicast bearer in the 4G network to the single in the 5G network first. And then switch from the unicast bearer in the 5G network to the 5G multicast session, thereby omitting the establishment of the unicast QoS flow in the 5G network, and shortening the time to switch the multicast service from the MBMS bearer to the 5G multicast session .

On the basis of Embodiment 1 and Embodiment 2, FIG. 11 is a signaling flowchart of the method for switching multicast services provided in Embodiment 6 of this application. The difference from Embodiment 3 is that this embodiment uses the third method mentioned above. Take the multicast service switching method as an example for description. As shown in FIG. 11, the method provided in this embodiment includes the following steps:

S601. Establish a PDN connection.

S602. The terminal device sends a first report to the AS, where the first report is used to instruct the terminal device to move out of the MBMS area.

S603. The AS sends a second message to the PCF, where the second message includes the first indication information and the sixth indication information.

S604. The PCF sends a first message to the PGW-C+SMF, where the first message includes the first indication information and the sixth indication information.

S605. PGW-C+SMF establishes a unicast bearer for services that support multicast transmission.

S606. PGW-C+SMF sends a fifth notification message to the AS.

S607. The AS sends a sixth notification message to the terminal device.

Steps 501-507 are basically similar to steps S301-S307 in the third embodiment. The difference is that: in this embodiment, the description information of the service sent by the AS is the second description information when it is sent in the second case above. Correspondingly, the first One indication information includes the second rule, the second rule is determined by the PCF according to the second description information, and the second rule does not include the third indication information. In the third embodiment, the description information of the service sent by the AS is the first description information when it is sent in the above case 1. The first indication information includes the first rule, and the first rule is that the PCF according to the first description information It is determined that the third instruction information is included in the first rule. In addition, in this embodiment, the first message and the second message include the sixth indication information. In the third embodiment, the first message and the second message sent by the AS do not include the sixth indication information.

S608: The terminal device is switched from the 4G network to the 5G network.

S609. PGW-C+SMF sends the first notification message to the AS.

In this embodiment, the terminal device according to the sixth instruction information, after the terminal device has successfully switched from the 4G network to the 5G network (that is, when the PGW-C+SMF is in the capital switching completion instruction information), and determines that the terminal device supports the 5G group When broadcasting the service, the first notification message is sent to the AS. The first notification message is used to notify that it supports or will support the use of multicast to send the data of the service to the terminal device, or is used to notify the terminal device to switch to the 5G network , Or, a method used to notify the AS of the usage status to send the data of the service to the terminal device.

In other embodiments of the present application, PGW-C+SMF may also send the first notification message to the AS when the terminal device is ready for handover, that is, PGW-C+SMF sends the first notification message when receiving the handover preparation instruction information .

Of course, PGW-C+SMF can also send the first notification message at other times after receiving the handover preparation, which is not limited.

S610. The AS sends a request message for adding the terminal device to the multicast session to the PCF.

The AS determines to add the terminal device to the 5G multicast session according to the first notification message, and notifies the core network device to add the terminal device to the 5G multicast session.

S611. The PCF sends fifth indication information to PGW-C+SMF.

The PCF adds the terminal device to the 5G multicast session according to the AS instruction, and sends fifth instruction information to PGW-C+SMF to instruct the PGW-C+SMF to add the terminal device to the 5G multicast session.

S612: Add the terminal device to the 5G multicast session corresponding to the service according to the fifth instruction information.

For the specific implementation of step S612, refer to the description of step S309 in the third embodiment, which will not be repeated here.

S613. PGW-C+SMF sends a third notification message to the AS.

S614. The AS sends a fourth notification message to the terminal device.

Steps S613 and S614 are optional steps.

S615. Delete the unicast QoS flow.

For the specific implementation of steps S613-615, refer to the related description of steps S310-S312 in the third embodiment, which will not be repeated here.

In other embodiments of the present application, after receiving the first notification message, the AS may also send a second notification message to the terminal device to notify the terminal device to use the 5G multicast session to receive data, and the terminal device sends the PGW-C to the PGW-C according to the second notification message. +SMF is sent to the fifth instruction message.

On the basis of Embodiment 1 and Embodiment 2, FIG. 12 is a signaling flowchart of the method for switching multicast services provided in Embodiment 7 of this application. This embodiment takes the above-mentioned first multicast service switching method as an example. Note that the data transmitted by the MBMS bearer is first switched from the MBMS bearer to the unicast bearer in the 4G network. During the switching process of the terminal device from the 4G network to the 5G network, PGW-C+SMF transfers the data transmitted by the MBMS bearer from 4G The unicast bearer in the network is switched to the PDU session (that is, the unicast path in the 5G network). After the terminal device is switched from the 4G network to the 5G network, PGW-C+SMF will join the terminal device to the 5G multicast session, that is, from 5G The unicast path in the network is switched to the 5G multicast path.

In this embodiment, the AS first sends the data to the UPF, and then sends the data to the PGW-U+UPF through the UPF.

Before the process of this embodiment, the AS sends the multicast service information of the service to the core network device, where the multicast service information includes service description information when the service is sent in a multicast manner, such as quintuple information. Exemplarily, the destination IP address in the service description information in the multicast service information of the service is the multicast IP address used when the service is sent in a multicast manner. The multicast service information also includes the QoS requirement information of the service, for example, the bandwidth requirement when the service is sent in the multicast mode. Here, the core network equipment refers to PCF or NEF. When the core network equipment is NEF, NEF receives the multicast service information of the service and saves it in the UDR, and the UDR sends the multicast service information of the service to the PCF. . The PCF determines the multicast PCC rule of the service according to the multicast service information of the service and sends it to the second SMF. The second SMF can determine the multicast QoS flow information of the service according to the multicast service information of the service. The information includes the multicast service identifier. For the specific determination process, please refer to the prior art and will not be repeated.

Optionally, the multicast service information of the service further includes eighth indication information, where the eighth indication information is used to indicate that the service supports service continuity when switching across systems. If the multicast service information includes the eighth indication information, the PCF sends the eighth indication information to the second SMF to indicate that the service needs to support service continuity during cross-system handover. Here, in order to simplify the description, the instruction information received by the PCF and the instruction information sent by the PCF to the second SMF are both called the eighth instruction information. In actual applications, different names can also be used, but both are used to indicate the service. Need to support business continuity. Here, business continuity refers to ensuring that the data packets of the business are not lost and/or sent in order when the terminal device is moving.

5 and 12, the method provided in this embodiment includes the following steps:

S701. Establish a PDN connection.

S702. The terminal device sends a first report to the AS, where the first report is used to instruct the terminal device to move out of the MBMS area.

For the specific implementation of S701-S702, refer to the description of steps S301 and S302 in the third embodiment, which will not be repeated here.

S703. The AS sends a second message to the PCF, where the second message includes the first indication information and the multicast service identifier.

The multicast service identifier may be TMGI or other identification information, which is not limited in this embodiment. The first indication information is used to indicate that a data packet of a service is sent to a terminal device located in the first network through a unicast bearer.

It should be noted that the multicast service identifier may also be included in the first instruction information and sent to the PCF.

S704. The PCF sends a first message to the PGW-C+SMF, where the first message includes the first indication information and the multicast service identifier.

It should be noted that the multicast service identifier may also be included in the first indication information and sent to PGW-C+SMF.

Both the first message and the second message carry the first indication information. In specific implementation, different message names can be used, but their functions are both used to indicate that the service data is sent to the terminal device through a unicast bearer. For ease of description, they are all referred to as first indication information in this embodiment.

S705. The PGW-C+SMF obtains the multicast QoS flow information of the service according to the multicast service identifier.

In the embodiment of this application, the PGW-C+SMF can obtain the multicast QoS flow information of the service according to the multicast service identifier. PGW-C+SMF can request the multicast QoS flow information of the service from the second SMF according to the multicast service identifier, and the second SMF can obtain the multicast service information according to the multicast service identifier, and determine the multicast of the service according to the multicast service information For the specific determination process of the QoS flow information, please refer to the prior art, which will not be repeated here.

The multicast QoS flow information of the service includes the information of one or more QoS flows of the service, and the information of one QoS flow includes the QFI of the QoS flow and the service identification information (for example, five-tuple or service Identification, where the destination address in the 5-tuple information is the multicast IP address of the service), the QoS parameters of the QoS flow (for example, the 5QI corresponding to the QoS flow, the maximum bandwidth requirement, etc.).

In one implementation, PGW-C+SMF can obtain the multicast QoS flow information of the service from UDM/UDR. Specifically, PGW-C+SMF sends the multicast service identifier to UDM/UDR so that UDM/UDR The UDR obtains the multicast QoS flow information of the service according to the multicast service identifier. The multicast QoS flow information of the service stored in the UDM/UDR may be stored in the UDM/UDR by the second SMF. For example, the second SMF obtains the information of the service from the PCF, for example, the PCC rules of the service, and according to The PCC rule of the service obtained from the PCF determines the multicast QoS flow information of the service. After the multicast QoS flow information is determined, the second SMF is the multicast QoS flow information of the service and the multicast service identifier of the service, The identification information of the second SMF is saved to UDM/UDR together.

In another implementation manner, PGW-C+SMF obtains the multicast QoS flow information of the service from the second SMF. When PGW-C+SMF receives the first message, PGW-C+SMF sends the multicast service identifier to the second SMF, and the second SMF sends the multicast QoS flow information of the service to PGW- according to the multicast service identifier. C+SMF. The PGW-C+SMF can obtain the information of the second SMF corresponding to the service from the UDM/UDR according to the multicast service identifier, so as to obtain the multicast QoS flow information of the service from the second SMF.

If the service needs to support service continuity when moving across systems, the second SMF or UDM/UDR sends eighth indication information to PGW-C+SMF to indicate that the service needs to support service continuity.

S706. The PGW-C+SMF establishes a unicast bearer for the service according to the multicast QoS flow information of the service.

The PGW-C+SMF determines the unicast bearer for sending the data packet of the service according to the multicast QoS flow information of the service, and the unicast bearer may be an EPS bearer. Exemplarily, PGW-C+SMF can map one or more multicast QoS streams to one EPS bearer. PGW-C+SMF can map the multicast QoS flow of the service to an existing EPS bearer, and it can also map the multicast QoS flow of the service to a new EPS bearer.

PGW-C+SMF can map part of the multicast QoS flow to the existing bearer, and part of the multicast QoS flow to the new bearer; or, PGW-C+SMF can map all the multicast QoS flows to the existing bearer; or PGW-C+SMF maps all multicast QoS flows to the new bearer, which is not limited in this embodiment.

In addition, if the PGW-C+SMF receives the eighth indication information, that is, the service supports service continuity, in order for the service to switch from unicast bearer transmission through the first network to PDU through the second network Session transmission. In this step, PGW-C+SMF also determines the parameters of the corresponding unicast QoS flow when the service is sent through the PDU session of the second network. For example, PGW-C+SMF can be used for one or more A multicast QoS flow is mapped to a unicast QoS flow, and the QoS parameters of the unicast QoS flow are determined according to the QoS parameters of the service data flow mapped to the unicast QoS flow. If there is no need to send the unicast QoS flow information to the terminal device, the process of determining the unicast QoS flow can also be performed during the handover, that is, step S711, which is not limited.

In the embodiment of the present application, establishing a unicast bearer for the service includes modifying the bearer (if the multicast QoS flow of the service is mapped to an existing bearer) and/or creating a bearer (if the multicast QoS flow of the service is mapped to a new bearer). After PGW-C+SMF establishes a unicast bearer, PGW-C+SMF informs the SGW to modify the bearer (if the multicast QoS flow of the service is mapped to the existing bearer) and/or create a bearer (if the multicast QoS of the service is mapped) In the new bearer), for details, please refer to the prior art, which will not be repeated in this embodiment. In this process, PGW-C+SMF obtains the first tunnel information of one or more EPS bearers corresponding to the service.

Optionally, in the process of modifying the bearer and/or creating the bearer, PGW-C+SMF sends the EPS bearer information corresponding to the service, including the bearer identifier, and the unicast QoS flow (including QFI) corresponding to the service to Terminal Equipment.

S707. PGW-C+SMF sends second indication information to PGW-U+UPF.

The second indication information is used to indicate that data packets are sent to the terminal device through the unicast bearer. After the PGW-C+SMF establishes the unicast bearer, the first mapping relationship is determined. The first mapping relationship is the QFI and the first mapping relationship of the multicast QoS flow of the service. The mapping relationship of the information of a tunnel, the information of the first tunnel is the tunnel information of the downlink node, the downlink node is the SGW or the access network equipment (when the SGW is co-located with other network elements), and each unicast bearer corresponds to a first tunnel.

The second indication information includes the first mapping relationship, used for PGW-U+UPF to determine the QFI of the data received from the second tunnel (the second tunnel is the tunnel between PGW-U+UPF and UPF) according to the first mapping relationship The corresponding unicast unicast bears the corresponding first tunnel information.

If the second tunnel has not been established, PGW-C+SMF requests PGW-U+UPF to allocate tunnel information of the second tunnel. PGW-U+UPF allocates the tunnel information of the second tunnel and sends it to PGW-C+SMF.

S708. PGW-C+SMF sends second tunnel information to the second SMF.

S709. The second SMF sends the second tunnel information to the UPF.

The UPF uses the second tunnel information to send the data packet of the service to the GW-U+UPF.

S710. The second SMF sends a response message to PGW-C+SMF.

After the establishment of the unicast bearer is completed, the AS can send service data through the unicast bearer. Optionally, after step S710, that is, after PGW-C+SMF receives the response message, PGW-C+SMF sends a fifth notification message to the AS, and the fifth notification message is used to notify the AS to use the unicast bearer to send the service The data is used to notify the AS network that the service data stream transmitted on the MBMS bearer has been switched or migrated to the unicast bearer.

Optionally, in response to the fifth notification message, the AS sends a sixth notification message to the terminal device. The sixth notification message is used to notify the terminal device to use the unicast bearer to receive the data of the service, or to notify the terminal device network The service data stream transmitted on the MBMS bearer has been switched or migrated to the unicast bearer.

S711. The terminal device is switched from the 4G network to the 5G network.

In this embodiment, the bearer corresponding to the service is switched to the 5G network only when the service supports service continuity. For the specific implementation of this step, refer to the description of step S308 in the third embodiment, which will not be repeated here.

It should be noted that the terminal device can also be added to the 5G multicast session corresponding to the service during the process of switching the terminal device from the 4G network to the 5G network, that is, steps S711-S712 are replaced with steps S508-S517.

S712. The terminal device is added to the 5G multicast session corresponding to the service.

For the specific implementation of this step, refer to the description of step S310 in the third embodiment, which will not be repeated here.

S713. Delete the unicast QoS flow.

For the specific implementation of step S713, refer to the description of step S312 in the third embodiment, which will not be repeated here.

Optionally, after step S712, PGW-C+SMF sends a third notification message to the AS, where the third notification message is used to notify the terminal device that it has switched to the 5G network, or to notify the AS to start using the 5G multicast session Send the data of the service to the terminal device. In response to the third notification message, the AS sends a fourth notification message to the terminal device, where the fourth notification message is used to notify the terminal device to use the 5G multicast session to receive the data of the service.

On the basis of Embodiment 1 and Embodiment 2, FIG. 13 is a signaling flowchart of the method for switching multicast services provided in Embodiment 8 of this application. The difference between this embodiment and Embodiment 7 is: in this embodiment, The data transmitted by the MBMS bearer does not switch from the MBMS bearer to the unicast bearer of the 4G network, but directly during the handover process of the terminal device from the 4G network to the 5G network. PGW-C+SMF creates a corresponding order for the service on the 5G network. After the terminal is switched to the 5G network, it can be sent through the unicast QoS stream. After the terminal device is switched from the 4G network to the 5G network, PGW-C+SMF will join the terminal device to the 5G multicast session, that is, from the 5G network The unicast path in is switched to the 5G multicast path. As shown in FIG. 13, the method of this embodiment may include the following steps:

S801. Establish a PDN connection.

For the specific implementation of S801, refer to the description of step S301 in the third embodiment, which will not be repeated here.

S802, PGW-C+SMF obtains the multicast service identifier of the service.

In one implementation, the terminal device sends a message to PGW-C+SMF through a PDN connection, and the message includes a multicast service identifier. For example, the terminal device sends an IGMP Join, and the PGW-C+SMF receives an IGMP Join message (the message passes through PGW-U+UPF is sent to PGW-C+SMF), IGMP Join includes multicast address information when the service is sent in multicast mode, and the multicast address information can be used to identify the service (that is, as a multicast service identifier) . It should be noted that the multicast service identifier of the service can include a variety of different identifiers, for example, multicast address information (for example, used to identify the service in an IGMP message), TMGI (for 4G MBMS identification of the service), Or 5G multicast service identifier (used to identify the service in the 5G network). In this implementation, the terminal device can send a multicast service identifier to PGW-C+SMF when it is determined that the service needs to be received. Further, the terminal device can send a multicast service identifier to PGW-C+SMF when it is determined that the service needs to support continuity. Multicast service identifier.

The terminal device sends the identifier of the multicast service through the PDN connection, so that PGW-C+SMF associates the service with the PDN connection, so that when the terminal device switches to the second network, the PGW-C+SMF can associate the service with the PDN connection. The PDU session corresponding to the PDN connection is associated, so that the terminal device can be added to the multicast session of the second network through the PDU session.

In another implementation, PGW-C+SMF receives the multicast service identifier from the AS. For example, when the terminal device and the AS are connected to the AS for application layer signaling interaction through the PDN connection, the AS sends the service to the core network device And the PCF sends the multicast service identifier to PGW-C+SMF. For example, when the AS sends the signaling description information of the application to the core network device, it sends the multicast service identifier of the service to the core network device, and the core network device (for example, PCF) sends the multicast service when sending the PCC rule corresponding to the signaling. The service identification is sent to PGW-C+SMF. The AS can send the multicast service identifier to the core network device when the service needs to support continuity. The AS may send the multicast service identifier of the service to the PGW-C+SMF after receiving the message requesting to receive the service sent by the terminal device.

S803. The PGW-C+SMF obtains the multicast QoS flow information of the service according to the multicast service identifier.

After the PGW-C+SMF obtains the multicast service identifier, it obtains the multicast QoS flow information of the service according to the multicast service identifier, and saves the multicast QoS flow information. Refer to the description of step S705 for the specific obtaining method, which will not be repeated here. Here, if PGW-C+SMF obtains the multicast service identifier from the terminal device, PGW-C+SMF can determine whether the terminal device is currently connected through the first network (for example, PGW-C+SMF can sense the interface with the downlink node The type is S5 interface or S8 interface, so it is judged that the terminal device is connected through the first network), if PGW-C+SMF judges that the terminal device is connected through the first network, PGW-C+SMF only obtains the multicast QoS flow of the service Information, do not establish a unicast bearer for this service.

S804. The terminal device switches from the 4G network to the 5G network, and creates a unicast QoS flow in the 5G network according to the multicast QoS flow information of the service during the switching process.

Since PGW-C+SMF does not create a unicast bearer for the service, that is, steps S702 to S710 in the seventh embodiment are not performed, during the handover process, PGW-C+SMF determines to pass according to the multicast QoS flow information of the service The corresponding unicast QoS flow information when the PDU session of the second network is sent. And send a request to create the unicast QoS flow to the target base station (i.e. gNB), so as to create a unicast QoS flow for the service on the second network during the handover process, so that it can pass through the second network immediately after switching to the second network. The PDU session sends the service. For the method of determining unicast QoS flow information according to the multicast QoS flow information, refer to step S706 in the seventh embodiment.

Optionally, in other embodiments of the present application, PGW-C+SMF may not establish a unicast QoS flow when the terminal device switches from a 4G network to a 5G network. Instead, the terminal device switches from a 4G network. In the process of reaching the 5G network, the terminal device directly joins the 5G multicast session corresponding to the service, that is, the service is directly switched from the MBMS bearer transmission to the 5G multicast session, without the need for 4G unicast bearer and 5G unicast QoS flow in the middle. And to ensure that the multicast service of the terminal equipment maintains the continuity of the service during the cell handover.

S805: Add the terminal device to the 5G multicast session corresponding to the service.

It should be noted that the terminal device can also be added to the 5G multicast session corresponding to the service when the terminal device is switched from the 4G network to the 5G network, that is, steps S804-S805 are replaced with steps S508-S517.

S806. Delete the unicast QoS flow.

For the specific implementation of step S806, refer to the description of step S312 in the third embodiment, which will not be repeated here.

Optionally, after step S806, PGW-C+SMF sends a third notification message to the AS, where the third notification message is used to notify the terminal device that it has switched to the 5G network, or used to notify the AS to start using the 5G multicast session Send the data of the service to the terminal device. In response to the third notification message, the AS sends a fourth notification message to the terminal device, where the fourth notification message is used to notify the terminal device to use the 5G multicast session to receive the data of the service.

In this method, PGW-C+SMF obtains the multicast service identifier of the service received by the terminal device through the multicast path of the first network (for example, 4G network) in advance, and obtains the multicast QoS of the service according to the multicast service identifier. Flow information, in the process of the terminal device switching from the first network to the second network (for example, 5G network), the unicast QoS flow information is established in the second network according to the multicast QoS flow information of the service, and the unicast QoS flow is established Later, the service can be sent to the terminal device through the unicast QoS flow, and subsequently when the terminal device switches to the second network, the terminal device is added to the 5G multicast session corresponding to the service. The method first switches the service from MBMS transmission to 5G unicast QoS streaming transmission, and then switches from 5G unicast QoS streaming transmission to 5G multicast session transmission, thereby ensuring that the terminal device is switched from the first network to the second network. During the network process, the multicast service data received by the terminal device through the multicast path of the first network maintains service continuity during the switching process.

It should be noted that the method of the fourth embodiment can not only be combined with the third embodiment, but also can be combined with the fifth embodiment, the sixth embodiment, the seventh embodiment or the eighth embodiment, that is, the method of the fourth embodiment can be combined with the fifth embodiment. Or, the method in the fourth embodiment is executed before the step S608 in the sixth embodiment, or the method in the fourth embodiment is executed before the step S711 in the seventh embodiment, or the method in the fourth embodiment is executed before the step S711 in the seventh embodiment. Executed before 804 in the Eighth Middle School.

FIG. 14 is a schematic structural diagram of a first session management network element according to Embodiment 9 of this application. As shown in FIG. 14, the first session management network element 100 includes:

The receiving module 11 is configured to receive first indication information, where the first indication information is used to indicate that a data packet of a service is sent to a terminal device located in the first network through a unicast bearer.

The sending module 12 is configured to send second instruction information to a first user plane network element, where the second instruction information is used to instruct to send the data packet to the terminal device through the unicast bearer.

The joining module 13 is configured to join the terminal device to the multicast session corresponding to the service when the terminal device accesses through the second network.

Optionally, the first session management network element 100 further includes: an obtaining module, configured to obtain multicast quality of service QoS flow information of the service; and a first determining module, configured to obtain multicast QoS flow information of the service according to the Determine the unicast bearer for sending the data packet of the service.

Optionally, the receiving module 11 is specifically configured to: receive a first message, where the first message includes the first indication information and the multicast service identifier of the service; the acquiring module is specifically configured to: The multicast service identifier obtains multicast QoS flow information of the service.

Alternatively, the first indication information includes a multicast service identifier of the service, and the obtaining module is specifically configured to obtain the multicast QoS flow information of the service according to the multicast service identifier.

Optionally, the first determining module is further configured to: if the first session management network element receives eighth indication information, the eighth indication information indicates that the service supports service continuity, according to the group The information of the broadcast QoS flow determines the unicast QoS flow corresponding to the service.

In an exemplary manner, the joining module 13 is specifically configured to: during the handover process of the terminal device from the first network to the second network, transfer the data packets of the service from passing through the single network. The broadcast bearer is sent to the terminal device to be sent to the terminal device via a protocol data unit PDU session. After the terminal device switches from the first network to the second network, the terminal device is added to the terminal device. In the multicast session, the data packet of the service is switched from being sent to the terminal through the PDU session to being sent to the terminal device through the multicast session.

Optionally, after the terminal device joins the multicast session, the sending module 12 is further configured to: notify the first user plane network element to stop sending the service to the terminal device through the PDU session data.

In another exemplary manner, the joining module 12 is specifically configured to: join the terminal device to the multicast session during the handover process of the terminal device from the first network to the second network The data packet of the service is switched from being sent to the terminal device via the unicast bearer to being sent to the terminal device via the multicast session.

In an exemplary manner, the joining module 13 is specifically configured to: receive a request message sent by the access and mobility management function AMF, where the request message is used to create or update a PDU session, and the PDU session is connected to the Service association, determining that the service sent through the unicast bearer supports multicast transmission, and the terminal device supports the multicast service in the second network, indicating the target access network in the second network The device joins the terminal device to the multicast session.

In an exemplary manner, when the terminal device moves into the MBMS area or after it moves into the MBMS area, the receiving module 11 is further configured to: receive fourth indication information, where the fourth indication information is used to instruct to stop passing through the The unicast bearer sends the data of the service. The sending module 12 is further configured to notify the first user plane network element to stop sending the service data through the unicast bearer according to the fourth instruction information.

Correspondingly, the receiving module 11 is further configured to: after the sending module sends the second indication information to the first user plane network element, receive the second tunnel information from the first user plane network element, and the first user plane network element A user plane network element receives the data packet of the service from a second user plane network element or an application server through the second tunnel. The sending module 12 is further configured to send the second tunnel information to the second user plane network element or the application server.

In an exemplary manner, after the terminal device switches to the second network, the sending module 12 is further configured to: send a first notification message to the AS, and the first notification message is used to notify the AS Support the use of multicast to send the service data to the terminal device. Correspondingly, the joining module 13 is specifically configured to: receive fifth instruction information, where the fifth instruction information is used to instruct the terminal device to join the multicast session corresponding to the service, and according to the fifth instruction information, Adding the terminal to the multicast session corresponding to the service.

Optionally, before the sending module 12 sends the first notification message to the AS, the receiving module 11 is further configured to: receive sixth indication information, where the sixth indication information is used to indicate when the multicast mode is supported When the terminal device sends service data, the first notification message is sent to the AS.

The first session management network element of this embodiment can be used to execute the method performed by the first session management network element in the foregoing method embodiment 1 to embodiment 6. The specific implementation manner and technical effect are similar, and details are not described herein again.

FIG. 15 is a schematic structural diagram of an AS provided in Embodiment 10 of this application. As shown in FIG. 15, the AS 200 includes:

The receiving module 21 is configured to receive a first report from a terminal device, where the first report is used to instruct the terminal device to move out of the MBMS area.

The determining module 22 is configured to determine, according to the first report, to send a data packet of a service to the terminal device through a unicast bearer.

The sending module 23 is configured to send first instruction information to a core network device and/or a first session management network element, where the first instruction information is used to instruct to send a data packet of the service to the terminal device through a unicast bearer .

Optionally, the sending module 23 is further configured to: send third indication information to the core network device and/or the first session management network element, where the third indication information is used to indicate that the service supports a multicast mode send.

Optionally, the sending module 23 sends third indication information to the core network device, specifically: sending a second message to the core network device, and the second message includes the third indication information and the core network device. The multicast service identifier corresponding to the service.

Optionally, the sending module 23 is further configured to: send sixth indication information to the core network device, where the sixth indication information is used to indicate when it supports sending service data to the terminal device in a multicast manner Sending the first notification message to the AS.

Optionally, the sending module 23 is further configured to send a multicast service identifier corresponding to the service to the core network device and/or the first session management network element.

In another exemplary manner, the sending module 23 sends a first message to the first session management network element, where the first message includes the first indication information and the multicast service identifier corresponding to the service . Alternatively, the sending module 23 sends a second message to the core network device, where the second message includes the first indication information and the multicast service identifier corresponding to the service.

In an exemplary manner, the receiving module 21 is further configured to: receive a first notification message, and the first notification message is used to notify that it supports the use of multicast to send the service data to the terminal device, so The sending module 23 is further configured to: in response to the first notification message, send a second notification message to the terminal device, where the second notification message is used to notify the terminal device to use the multicast session to receive the Business data.

In another exemplary manner, the receiving module 21 is further configured to: receive a first notification message, where the first notification message is used to notify that it supports the use of multicast to send the service data to the terminal device, The sending module 23 is further configured to: in response to the first notification message, send fifth indication information to the first session management network element or the core network device, where the fifth indication information is used to instruct the terminal The device joins the multicast session corresponding to the service.

In an exemplary manner, the receiving module 21 is further configured to: when the terminal device moves from a non-MBMS area into an MBMS area, receive a second report from the terminal device, and the second report is used to notify the The terminal equipment of the AS can receive the data of the service through the MBMS bearer. Correspondingly, the sending module 23 is further configured to send fourth instruction information to the core network device, where the fourth instruction information is used to instruct to stop sending the data of the service through the unicast bearer.

The AS in this embodiment can be used to execute the method executed by the AS in the foregoing method embodiment 1 to embodiment 6. The specific implementation and technical effects are similar, and will not be repeated here.

FIG. 16 is a schematic structural diagram of a terminal device provided in Embodiment 11 of this application. As shown in FIG. 16, the terminal device 300 includes:

The sending module 31 is configured to send multicast capability indication information to the first session management network element in the process of establishing a PDN connection for the terminal device, where the multicast capability indication information is used to indicate that the terminal device is in the Multicast capability in the second network.

The receiving module 32 is configured to receive, from the source access network device in the first network, the configuration information of the wireless resource allocated by the target access network device in the second network to the terminal device, and the configuration information of the wireless resource The terminal device is used for receiving the data of the service in the second network in a multicast manner; the receiving module is further used for receiving the data of the service according to the configuration information of the wireless resource.

In an exemplary manner, the receiving module 31 is further configured to: receive a fourth notification message from the application server AS, where the fourth notification message is used to notify the terminal device to use multicast in the second network The session receives the data of the service.

The terminal device of this embodiment can be used to execute the method executed by the terminal device in the first to sixth embodiments of the foregoing method. The specific implementation manner and technical effect are similar, and details are not described herein again.

FIG. 17 is a schematic structural diagram of a target access network device provided in Embodiment 12 of this application. As shown in FIG. 17, the target access network device 400 includes:

The receiving module 41 is configured to receive seventh indication information from the first session management network element, where the seventh indication information is used to indicate that the terminal device is added to the multicast session corresponding to the service.

The obtaining module 42 is configured to obtain the parameters of the multicast QoS flow of the multicast session.

The resource allocation module 43 is configured to allocate wireless resources for the multicast QoS flow according to the seventh indication information and the parameters of the multicast QoS flow.

The sending module 44 is configured to send the configuration information of the wireless resources of the multicast QoS flow to the terminal device through the source access network device, where the source access network device is the terminal device when the terminal device is accessing the target The access network device that is connected before the access network device.

The target access network device in this embodiment can be used to execute the methods executed by the target access network device in the first to sixth embodiments of the foregoing method. The specific implementation methods and technical effects are similar, and details are not described herein again.

FIG. 18 is a schematic structural diagram of a first session management network element provided by Embodiment 13 of this application. As shown in FIG. 18, the first session management network element 500 includes: a processor 51, a memory 52, a transceiver 53, and a memory 52 The transceiver 53 is connected to the processor 51 through a bus 54 to communicate, the memory 52 is used to store instructions, the transceiver 53 is used to communicate with other devices, and the processor 51 is used to execute the information stored in the memory 52. Instructions, so that the first session management network element 500 executes the method performed by the first session management network element in the first embodiment to the sixth embodiment.

It can be understood that the processor used by the first session management network element in the embodiment of the present application may be a central processing unit (CPU), a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), and a field programmable gate. Array (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. It can implement or execute various exemplary logical blocks, modules, and circuits described in conjunction with the disclosure of this application. The processor may also be a combination for realizing computing functions, for example, including a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and so on.

The bus described in the embodiments of this application may be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. . The bus can be divided into address bus, data bus, control bus and so on. For ease of representation, the buses in the drawings of this application are not limited to only one bus or one type of bus.

In the several embodiments provided in this application, it should be understood that the disclosed device and method may be implemented in other ways. For example, the device embodiments described above are merely illustrative, for example, the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or It can be integrated into another system, or some features can be ignored or not implemented. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, the functional units in the various embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware, or may be implemented in the form of hardware plus software functional units.

The above-mentioned integrated unit implemented in the form of a software functional unit may be stored in a computer readable storage medium. The above-mentioned software functional unit is stored in a storage medium, and includes several instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute the method described in each embodiment of the present application. Part of the steps. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disks or optical disks and other media that can store program codes. .

Claims

A method for switching multicast services, which is characterized in that it includes:

The first session management network element receives first indication information, where the first indication information is used to indicate that a data packet of a service is sent to a terminal device located in the first network through a unicast bearer;

Sending, by the first session management network element, second instruction information to the first user plane network element, where the second instruction information is used to instruct to send the data packet to the terminal device through the unicast bearer;

When the terminal device accesses through the second network, the first session management network element adds the terminal device to the multicast session corresponding to the service.
The method according to claim 1, further comprising:

Acquiring, by the first session management network element, the multicast service quality QoS flow information of the service;

The first session management network element determines the unicast bearer for sending the data packet of the service according to the multicast QoS flow information of the service.
The method according to claim 2, wherein the receiving of the first indication information by the first session management network element comprises:

Receiving, by the first session management network element, a first message, where the first message includes the first indication information and the multicast service identifier of the service;

The acquiring, by the first session management network element, the multicast QoS flow information of the service includes:

The first session management network element obtains the multicast QoS flow information of the service according to the multicast service identifier.
The method according to claim 2, wherein the first indication information includes a multicast service identifier of the service, and obtaining the multicast QoS flow information of the service by the first session management network element includes:

The first session management network element obtains the multicast QoS flow information of the service according to the multicast service identifier.
The method according to any one of claims 2-4, further comprising:

If the first session management network element receives eighth indication information indicating that the service supports service continuity, the first session management network element determines according to the information of the multicast QoS flow The unicast QoS flow corresponding to the service.
The method according to any one of claims 1-5, wherein the first session management network element adding the terminal device to the multicast session corresponding to the service comprises:

In the process of the terminal device switching from the first network to the second network, the first session management network element switches the data packet of the service from sending to the terminal device via the unicast bearer To the terminal device via a protocol data unit PDU session;

After the terminal device is switched from the first network to the second network, the first session management network element joins the terminal device to the multicast session, and the service data packet passes through the The PDU session sent to the terminal is switched to sent to the terminal device through the multicast session.
The method according to any one of claims 1-5, wherein the first session management network element adding the terminal device to the multicast session corresponding to the service comprises:

During the handover of the terminal device from the first network to the second network, the first session management network element joins the terminal device to the multicast session, and the service data packet passes through all the The unicast bearer sent to the terminal device is switched to sent to the terminal device through the multicast session.
The method according to claim 1, wherein the first session management network element adding the terminal device to the multicast session corresponding to the service comprises:

In the process of the terminal device switching from the first network to the second network, the first session management network element switches the data packet of the service from sending to the terminal device via the unicast bearer To the terminal device via a protocol data unit PDU session;

After the terminal device is switched from the first network to the second network, the first session management network element joins the terminal device to the multicast session, and the service data packet passes through the The PDU session sent to the terminal is switched to sent to the terminal device through the multicast session.
The method according to claim 1, wherein the first session management network element adding the terminal device to the multicast session corresponding to the service comprises:

During the handover of the terminal device from the first network to the second network, the first session management network element joins the terminal device to the multicast session, and the service data packet passes through all the The unicast bearer sent to the terminal device is switched to sent to the terminal device through the multicast session.
The method according to any one of claims 1, 8, and 9, characterized in that, before the first session management network element joins the terminal device to the multicast session, the method further comprises:

The first session management network element determines that the service supports sending through the multicast mode of the second network.
The method according to claim 10, wherein the first session management network element determining that the service supports sending through the multicast mode of the second network comprises:

The first session management network element receives a first rule corresponding to the service, where the first rule is used for control, policy, or charging, and the first rule includes third indication information, and the third indication The information is used to indicate that the service supports multicast transmission.
The method according to any one of claims 6-9, wherein before the first session management network element joins the terminal device to the multicast session, the method further comprises:

The first session management network element determines that the terminal device supports multicast in the second network, and/or the target access network device supports multicast, wherein the terminal device passes through the target access network The device accesses the second network.
The method according to claim 12, further comprising:

The first session management network element receives multicast capability indication information sent by the terminal device during the process of establishing a packet data network PDN connection by the terminal device, where the multicast capability indication information is used to instruct the terminal device Multicast capability in the second network;

The determining, by the first session management network element, that the terminal device supports multicast in the second network includes:

The first session management network element determines, according to the multicast capability indication information, that the terminal device supports multicast in the second network.
The method according to claim 6 or 8, wherein after the terminal device joins the multicast session, the method further comprises:

The first session management network element notifies the first user plane network element to stop sending the service data to the terminal device through the PDU session.
The method according to any one of claims 1-14, wherein the method further comprises:

When the terminal device moves into the MBMS area of the multimedia broadcast multicast service or after it moves into the MBMS area, the first session management network element receives fourth indication information, and the fourth indication information is used to instruct to stop passing the unicast bearer Sending data of the service;

The first session management network element notifies the first user plane network element to stop sending the service data through the unicast bearer according to the fourth instruction information.
The method according to claim 1, wherein the second indication information includes a first mapping relationship between the information of the first tunnel and the identifier QFI of the multicast quality of service QoS flow of the service, and the first tunnel Is the tunnel corresponding to the unicast bearer, the QFI is the QFI of the service data packet received by the first user plane network element, and the first mapping relationship is used for the first user plane network element Determine the first tunnel for sending the data packet of the service.
The method according to claim 16, wherein after the first session management network element sends the second indication information to the first user plane network element, the method further comprises:

The first session management network element receives information about the second tunnel from the first user plane network element, and the first user plane network element receives all information from a second user plane network element or an application server through the second tunnel. The data package of the business;

The first session management network element sends the second tunnel information to the second user plane network element or the application server.
The method according to claim 1, wherein the second indication information includes the multicast address, and the second indication information is used to instruct the first user plane network element to set the destination address as the The data packet of the multicast address is sent to the terminal device through the unicast bearer.
The method according to claim 1, wherein after the terminal device switches to the second network, the method further comprises:

Sending, by the first session management network element, a first notification message to the application server AS, where the first notification message is used to notify the AS to support the use of multicast to send the service data to the terminal device;

The adding, by the first session management network element, the terminal device to the multicast session corresponding to the service includes:

Receiving, by the first session management network element, fifth indication information, where the fifth indication information is used to instruct to add the terminal device to the multicast session corresponding to the service;

The first session management network element adds the terminal to the multicast session corresponding to the service according to the fifth instruction information.
The method according to claim 19, wherein before the first session management network element sends the first notification message to the application server AS, the method further comprises:

The first session management network element receives sixth indication information, where the sixth indication information is used to indicate to send the first notification message to the AS when it supports the use of multicast to send service data to the terminal device .
The method according to claim 19 or 20, wherein before the first session management network element joins the terminal device to the multicast session, the method further comprises:

The first session management network element determines that the terminal device supports multicast in the second network, and/or the target access network device supports multicast, wherein the terminal device passes through the target access network The device accesses the second network.
A first session management network element, characterized in that it comprises:

A receiving module, configured to receive first indication information, where the first indication information is used to instruct to send a service data packet to a terminal device located in the first network through a unicast bearer;

A sending module, configured to send second instruction information to a first user plane network element, where the second instruction information is used to instruct to send the data packet to the terminal device through the unicast bearer;

The joining module is configured to join the terminal device to the multicast session corresponding to the service when the terminal device accesses through the second network.
The network element according to claim 22, further comprising:

An obtaining module, configured to obtain multicast service quality QoS flow information of the service;

The first determining module is configured to determine the unicast bearer for sending the data packet of the service according to the multicast QoS flow information of the service.
The network element according to claim 23, wherein the receiving module is specifically configured to:

Receiving a first message, where the first message includes the first indication information and the multicast service identifier of the service;

The obtaining module is specifically used for:

Acquire the multicast QoS flow information of the service according to the multicast service identifier.
The network element according to claim 23, wherein the first indication information includes a multicast service identifier of the service, and the obtaining module is specifically configured to:

Acquire the multicast QoS flow information of the service according to the multicast service identifier.
The network element according to any one of claims 23-25, wherein the first determining module is further configured to:

If the first session management network element receives eighth indication information indicating that the service supports service continuity, determine the unicast QoS corresponding to the service according to the information of the multicast QoS flow flow.
The network element according to any one of claims 22-26, wherein the joining module is specifically configured to:

In the process of the terminal device switching from the first network to the second network, the service data packet is switched from being sent to the terminal device via the unicast bearer to being sent via a protocol data unit PDU session To the terminal device;

After the terminal device is switched from the first network to the second network, the terminal device is added to the multicast session, and the data packet of the service is switched from being sent to the terminal through the PDU session To the terminal device through the multicast session.
The network element according to any one of claims 22-26, wherein the joining module is specifically configured to:

During the handover process of the terminal device from the first network to the second network, the terminal device is added to the multicast session, and the data packet of the service is sent to the unicast bearer from the The terminal device switches to send to the terminal device through the multicast session.
The network element according to claim 22, wherein the adding module is specifically configured to:

In the process of the terminal device switching from the first network to the second network, the service data packet is switched from being sent to the terminal device via the unicast bearer to being sent via a protocol data unit PDU session To the terminal device;

After the terminal device is switched from the first network to the second network, the terminal device is added to the multicast session, and the data packet of the service is switched from being sent to the terminal through the PDU session To the terminal device through the multicast session.
The network element according to claim 22, wherein the adding module is specifically configured to:

During the handover process of the terminal device from the first network to the second network, the terminal device is added to the multicast session, and the data packet of the service is sent to the unicast bearer from the The terminal device switches to send to the terminal device through the multicast session.
The network element according to any one of claims 22, 29 and 30, further comprising:

The second determining module is configured to determine that the service supports sending through the multicast mode of the second network before the joining module joins the terminal device to the multicast session.
The network element according to claim 31, wherein the second determining module is specifically configured to:

Receive a first rule corresponding to the service, where the first rule is used for control, policy, or charging, the first rule includes third indication information, and the third indication information is used to indicate that the service supports Send in multicast mode.
The network element according to any one of claims 27-30, further comprising:

The third determining module is configured to determine that the terminal device supports multicast in the second network, and/or the target access network device supports multicast, wherein the terminal device passes through the target access network device Access to the second network.
The network element according to claim 33, wherein the receiving module is further configured to:

Receiving multicast capability indication information sent by the terminal device, where the multicast capability indication information is used to indicate the multicast capability of the terminal device in the second network;

The third determining module is specifically configured to:

It is determined according to the multicast capability indication information that the terminal device supports multicast in the second network.
The network element according to claim 27 or 29, wherein the sending module is further configured to:

After the terminal device joins the multicast session, notify the first user plane network element to stop sending the service data to the terminal device through the PDU session.
The network element according to any one of claims 22-35, wherein the receiving module is further configured to:

When the terminal device moves into the MBMS area of the multimedia broadcast multicast service or after moving into the MBMS area, receiving fourth indication information, where the fourth indication information is used to instruct to stop sending the data of the service through the unicast bearer;

The sending module is further configured to notify the first user plane network element to stop sending the service data through the unicast bearer according to the fourth instruction information.
The network element according to claim 22, wherein the second indication information comprises a first mapping relationship between the information of the first tunnel and the identifier QFI of the multicast quality of service QoS flow of the service, and the first A tunnel is a tunnel corresponding to the unicast bearer, the QFI is the QFI of the service data packet received by the first user plane network element, and the first mapping relationship is used for the first user plane network The element determines the first tunnel through which the data packet of the service is sent.
The network element according to claim 37, wherein the receiving module is further configured to:

After the sending module sends the second indication information to the first user plane network element, it receives the second tunnel information from the first user plane network element, and the first user plane network element receives information from the first user plane network element through the second tunnel. The second user plane network element or the application server receives the data packet of the service;

The sending module is further configured to send the second tunnel information to the second user plane network element or the application server.
The network element according to claim 22, wherein the second indication information includes the multicast address, and the second indication information is used to instruct the first user plane network element to set the destination address as the destination address. The data packet of the multicast address is sent to the terminal device through the unicast bearer.
The network element according to claim 22, wherein after the terminal device is switched to the second network, the sending module is further configured to:

Sending a first notification message to the application server AS, where the first notification message is used to notify the AS to support the use of multicast to send the service data to the terminal device;

The joining module is specifically used for:

Receiving fifth instruction information, where the fifth instruction information is used to instruct to add the terminal device to the multicast session corresponding to the service;

According to the fifth instruction information, the terminal is added to the multicast session corresponding to the service.
The network element according to claim 40, wherein before the sending module sends the first notification message to the application server AS, the receiving module is further configured to:

Receiving sixth indication information, where the sixth indication information is used to indicate that the first notification message is sent to the AS when a multicast mode is supported to send service data to the terminal device.
The network element according to claim 40 or 41, further comprising:

The determining module is configured to determine that the terminal device supports multicast in the second network, and/or the target access network device supports multicast, wherein the terminal device accesses through the target access network device The second network.
A communication system, characterized by comprising: a first session management network element and an application server AS;

The AS is configured to receive a first report from a terminal device of a first network, where the first report is used to instruct the terminal device to move out of the MBMS area of the multimedia broadcast multicast service; Sending service data packets to the terminal device by the broadcast bearer; and sending first indication information to the first session management network element, where the first indication information is used to indicate that the unicast bearer is used to send the Business data package;

The first session management network element is used to receive the first indication information; to send second indication information to the first user plane network element, and the second indication information is used to indicate to the terminal through the unicast bearer The device sends the data packet; and when the terminal device accesses through the second network, the first session management network element adds the terminal device to the multicast session corresponding to the service.
The system according to claim 43, wherein the system further comprises the first user plane network element.
The system according to claim 43, wherein after the terminal device switches to the second network, the first session management network element is further configured to send a first notification message to the application server AS, and the first A notification message is used to notify the AS to support the use of multicast to send the service data to the terminal device; and specifically to receive fifth indication information, which is used to instruct the terminal device Join the multicast session corresponding to the service, and add the terminal to the multicast session corresponding to the service according to the fifth instruction information.
A computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the method for switching multicast services according to any one of claims 1-21 when the computer program is executed by a processor.
A computer program product, comprising a computer program, characterized in that, when the computer program is executed by a processor, the method for switching the multicast service according to any one of claims 1-21 is realized.