Communication method and apparatus

Abstract

The present application provides a communication method and apparatus for ensuring service continuity of MBS of a terminal device in a cell handover process, and relates to the field of communication technology. The method includes a first access network device configuring a first radio bearer currently used to carry MBS between the first access network device and the terminal device as a second radio bearer used to carry unicast services. The first access network device sends the MBS to the terminal device in unicast mode via the second radio bearer. In this way, in a process in which the terminal device is subsequently handed over to the second access network device, the first access network device and the second access network device directly switch the MBS being transmitted in a manner of switching the current unicast service to the second access network device. This solves the disruption of MBS caused by the second access network device not supporting the multicast-broadcast transmission mode.

Description

[Technical field]

[0001] The present application relates to the field of communication technologies, and in particular to communication methods and devices. [Background technology]

[0002] A multicast and broadcast service (MBS) is a service that is transmitted by an access network device to multiple terminal devices. Common MBS services include live broadcast services, public security services, batch software update services, etc.

[0003] As shown in Fig. 1, in the transmission process, the MBS is sequentially transmitted to the terminal device via the MBS server, the core network device, and the access network device. The MBS is transmitted between the MBS server and the core network device via a common transmission channel (MBS service). The MBS is transmitted between the core network device and the access network device via a common transmission channel MBS session, and each MBS session includes at least one MBS quality of service (QoS) flow. The MBS is transmitted between the access network device and the terminal device via the MBS radio bearer (MRB). Usually, the MBS has two transmission modes, namely, a point-to-multipoint (PTM) transmission mode and a point-to-point (PTP) transmission mode.

[0004] In a mobile communication system, in a mobility process, a terminal device needs to be handed over from one cell to another cell when the signal strength of each cell changes. However, when a target base station does not support a multicast / broadcast transmission mode, in a process of handing over a terminal device to a target base station, the MBS cannot continue to be received in the multicast / broadcast mode. As a result, the service continuity of the MBS in the handover process of the terminal device cannot be guaranteed. Summary of the Invention

[0005] The present application provides a communication method and apparatus for solving a problem in the prior art that service continuity of MBS cannot be guaranteed when a terminal device is handed over from a cell that supports a multicast / broadcast transmission mode to a cell that does not support the multicast / broadcast transmission mode.

[0006] In order to achieve the aforementioned objectives, the following technical solutions are used in this application.

[0007] According to a first aspect, there is provided a communication method, including a terminal device receiving first indication information, the first indication information instructing the terminal device to configure a first radio bearer as a second radio bearer, the first radio bearer being a multicast radio bearer and the second radio bearer being a unicast radio bearer.

[0008] The terminal device receives the MBS via the second radio bearer.

[0009] According to the aforementioned technical solution, when a terminal device needs to be handed over from a first access network device supporting a multicast / broadcast transmission mode to a second access network device not supporting a multicast / broadcast transmission mode, the first access network device configures a first radio bearer currently used to carry MBS between the first access network device and the terminal device as a second radio bearer used to carry unicast services, and the first access network device sends the MBS to the terminal device in a unicast mode via the second radio bearer.

[0010] In this way, the MBS is transmitted between the terminal device and the first access network device in unicast mode. Therefore, in the process of the terminal device being subsequently handed over to the second access network device, the first access network device and the second access network device directly switch the transmitted MBS to the second access network device in a manner of switching the current unicast service. This solves the interruption of the MBS caused by the second access network device not supporting the multicast / broadcast transmission mode.

[0011] In relation to the first aspect, in a possible implementation, the first indication information specifically indicates at least one of the following information of the second radio bearer: packet data convergence protocol (PDCP) setting information, radio link control (RLC) setting information, security setting information, and an identifier of the second radio bearer.

[0012] Based on this, the terminal device can determine configuration information of the second radio bearer based on the first indication information, whereby the terminal device configures the second radio bearer based on the configuration information.

[0013] In relation to the first aspect, in a possible implementation, the second radio bearer still uses at least one of the following configuration information of the first radio bearer: PDCP configuration information, and PTP RLC configuration information.

[0014] On this basis, the second radio bearer still uses the PDCP configuration information and / or the PTP RLC configuration information of the first radio bearer, so that the terminal device does not need to reconfigure the PDCP configuration and the RLC configuration when setting up the second radio bearer, which reduces the implementation complexity of the terminal device.

[0015] In relation to the first aspect, in a possible implementation, the PDCP entity corresponding to the second radio bearer still uses the transmission status and transmission parameters, which are the transmission window of the PDCP entity corresponding to the first radio bearer.

[0016] Based on this, the consistency of the PDCP entity after reconfiguration can be guaranteed, and the cases where data packets are lost due to reconfiguration can be reduced.

[0017] According to a second aspect, a communication method is provided, including a first access network device sending first indication information. The first indication information instructs a terminal device to configure a first radio bearer as a second radio bearer. The first radio bearer is a multicast radio bearer and the second radio bearer is a unicast radio bearer. The first access network device sends the MBS via the second radio bearer.

[0018] In relation to the second aspect, in a possible implementation, the first indication information specifically indicates at least one of the following information of the second radio bearer: PDCP setting information, RLC setting information, security setting information, and an identifier of the second radio bearer.

[0019] In relation to the second aspect, in a possible implementation, the second radio bearer still uses at least one of the following configuration information of the first radio bearer: PDCP configuration information, and PTP RLC configuration information.

[0020] In relation to the second aspect, in a possible implementation, the PDCP entity corresponding to the second radio bearer still uses the transmission status and transmission parameters, which are the transmission window of the PDCP entity corresponding to the first radio bearer.

[0021] In relation to the second aspect, in a possible implementation, the method further includes the first access network device sending second indication information, the second indication information instructing the core network device to send the MBS to the first access network device via a unicast session or a unicast quality of service flow corresponding to the terminal device.

[0022] Based on this, when the MBS is transmitted between the first access network device and the terminal device in a unicast mode, the MBS is also transmitted between the first access network device and the core network device in a unicast mode, which can increase the consistency of transmitting the MBS between the core network device, the first access network device, and the terminal device.

[0023] In relation to the second aspect, in a possible implementation, the second indication information further indicates a data packet serial number, the data packet serial number being the serial number of the first data packet of the MBS sent by the core network device through the unicast session or the unicast quality of service flow.

[0024] Based on this, the first access network device can indicate the data packet at which the core network starts sending the MBS via the unicast session or unicast quality of service flow by using the data packet serial number.

[0025] According to a third aspect, there is provided a communication method, including a first access network device receiving third indication information, the third indication information indicating a correspondence relationship between a unicast quality of service flow and an MBS quality of service flow.

[0026] The first access network device maps the MBS quality of service flow to the unicast quality of service flow in the handover process based on the third indication information.

[0027] The first access network device forwards the unicast quality of service flow.

[0028] According to the above technical solution, before the terminal device is handed over to the second access network device, the first access network device and the terminal device continue to send MBS in multicast mode. In the process in which the terminal device performs cell handover, the first access network device instructs the terminal device to send MBS with the second access network in unicast mode. After handover, the MBS is sent between the terminal device and the second access network device in unicast mode. The first access network device sends the MBS that is not sent in unicast mode to the second access network device.

[0029] In this way, it can be ensured that the terminal device transmits the MBS in unicast mode after being handed over to the second access network device. This method ensures that the terminal device can still transmit the MBS correctly after being handed over to the second access network device. In addition, the handover procedure is similar to the existing handover procedure, is simple to implement, and can ensure the continuity of receiving the MBS by the terminal device.

[0030] In relation to the third aspect, in a possible implementation, the third indication information includes at least one of a flow identifier of a unicast quality of service flow corresponding to the MBS quality of service flow and a QoS parameter of the unicast quality of service flow.

[0031] Based on this, the access network device can determine, based on the third indication information, a unicast quality of service flow corresponding to the MBS quality of service flow, and parameter information of the unicast quality of service flow.

[0032] According to a fourth aspect, there is provided a communication method, including: a terminal device receiving fourth indication information, the fourth indication information instructing the terminal device to configure a second radio bearer as a first radio bearer, the first radio bearer being a multicast radio bearer and the second radio bearer being a unicast radio bearer.

[0033] The terminal device receives the MBS via the first radio bearer.

[0034] According to the above technical solution, an embodiment of the present application provides a communication method, in which when a terminal device is handed over from an access network device that does not support a multicast / broadcast transmission mode to an access network device that supports a multicast / broadcast transmission mode, if an MBS is transmitted between the terminal device and the access network device in a unicast mode, the MBS is mapped to an MBS transmitted in a multicast mode, which solves the waste of transmission resources caused by repeated transmission of the MBS.

[0035] In relation to the fourth aspect, in a possible implementation, the method further includes the terminal device delivering data packets in the PDCP entity corresponding to the first radio bearer to an upper layer protocol entity.

[0036] Based on this, the terminal device can deliver data packets in the PDCP entity to the upper layer protocol entity before reconfiguration, thereby avoiding data loss in the PDCP entity in the process of reconfiguring the PDCP entity.

[0037] In relation to the fourth aspect, in a possible implementation, the method further includes the terminal device performing at least one of the following operations for configuring the second radio bearer as the first radio bearer, namely, a step of establishing a PTM RLC entity, a step of configuring an MBS identifier, and a step of deleting a security configuration in the second radio bearer configuration.

[0038] Based on this, the terminal device may obtain the first radio bearer by configuring a PTP RLC entity in the second radio bearer, and / or by configuring an MBS network identifier, and / or by deleting the security configuration in the second radio bearer configuration.

[0039] In relation to the fourth aspect, in a possible implementation, the method further includes the terminal device sending fifth indication information to the third access network device, the fifth indication information indicating a serial number corresponding to the data packet that is not successfully received by the terminal device.

[0040] Based on this, the third access network device can determine the data packets that need to be sent to the terminal device after reconfiguration of the radio bearer based on the serial numbers corresponding to the data packets that were not successfully received.

[0041] According to a fifth aspect, there is provided a communication device including a communication unit and a processing unit.

[0042] The processing unit is configured to instruct the communication unit to receive first indication information, the first indication information instructing the terminal device to configure the first radio bearer as a second radio bearer, the first radio bearer being a multicast radio bearer and the second radio bearer being a unicast radio bearer.

[0043] The processing unit is further configured to instruct the communication unit to receive the MBS via the second radio bearer.

[0044] In relation to the fifth aspect, in a possible implementation, the first indication information specifically indicates at least one of the following information of the second radio bearer: PDCP setting information, RLC setting information, security setting information, and an identifier of the second radio bearer.

[0045] In relation to the fifth aspect, in a possible implementation, the second radio bearer still uses at least one of the following configuration information of the first radio bearer: PDCP configuration information, and point-to-point PTP RLC configuration information.

[0046] In relation to the fifth aspect, in a possible implementation, the PDCP entity corresponding to the second radio bearer still uses the transmission status and transmission parameters, which are the transmission window of the PDCP entity corresponding to the first radio bearer.

[0047] According to a sixth aspect, there is provided a communication device including a communication unit and a processing unit.

[0048] The processing unit is configured to instruct the communication unit to send first indication information, the first indication information instructing the terminal device to configure the first radio bearer as a second radio bearer, the first radio bearer being a multicast radio bearer and the second radio bearer being a unicast radio bearer.

[0049] The processing unit is further configured to instruct the communication unit to send the MBS over a second radio bearer.

[0050] In relation to the sixth aspect, in a possible implementation, the first indication information specifically indicates at least one of the following information of the second radio bearer: PDCP setting information, RLC setting information, security setting information, and an identifier of the second radio bearer.

[0051] In relation to the sixth aspect, in a possible implementation, the second radio bearer still uses at least one of the following configuration information of the first radio bearer: PDCP configuration information, and PTP RLC configuration information.

[0052] In relation to the sixth aspect, in a possible implementation, the PDCP entity corresponding to the second radio bearer still uses the transmission status and transmission parameters, which are the transmission window of the PDCP entity corresponding to the first radio bearer.

[0053] In relation to the sixth aspect, in a possible implementation, the processing unit is further configured to instruct the communication unit to send second indication information, the second indication information instructing the core network device to send the MBS to the first access network device via a unicast session or a unicast quality of service flow corresponding to the terminal device.

[0054] In relation to the sixth aspect, in a possible implementation, the second indication information further indicates a data packet serial number, the data packet serial number being the serial number of the first data packet of the MBS sent by the core network device through the unicast session or the unicast quality of service flow.

[0055] According to an aspect of a seventh aspect there is provided a communication device including a communication unit and a processing unit.

[0056] The processing unit is configured to instruct the communication unit to receive third indication information, the third indication information indicating a correspondence relationship between the unicast quality of service flow and the MBS quality of service flow.

[0057] The processing unit is further configured to map the MBS quality of service flows to unicast quality of service flows in the handover process based on the third indication information.

[0058] The processing unit is further configured to instruct the communication unit to forward the unicast quality of service flow.

[0059] In relation to the seventh aspect, in a possible implementation, the third indication information includes at least one of a flow identifier of a unicast quality of service flow corresponding to the MBS quality of service flow and a QoS parameter of the unicast quality of service flow.

[0060] According to an aspect of an eighth aspect there is provided a communication device including a communication unit and a processing unit.

[0061] The processing unit is configured to instruct the communication unit to receive fourth indication information, the fourth indication information instructing the terminal device to configure the second radio bearer as the first radio bearer, the first radio bearer being a multicast radio bearer and the second radio bearer being a unicast radio bearer.

[0062] The processing unit is further configured to instruct the communication unit to receive the MBS via the first radio bearer.

[0063] In relation to the eighth aspect, in a possible implementation, the processing unit Deliver the data packet in the PDCP entity corresponding to the first radio bearer to an upper layer protocol entity. It is further structured as follows.

[0064] According to an embodiment of the ninth aspect, the present application provides a communication device including a processor, a storage medium, at least one processor, and an interface circuit. The interface circuit is configured to receive a signal from another communication device other than the communication device, transmit a signal to the processor, or transmit a signal from the processor to another communication device other than the communication device. The processor is configured to implement the method according to the first aspect and any one of the possible implementations of the first aspect by using a logic circuit or executing code instructions. The communication device may be a terminal device or may be a chip in the terminal device.

[0065] According to an embodiment of the tenth aspect, the present application provides a communication device including a processor, a storage medium, at least one processor, and an interface circuit. The interface circuit is configured to receive a signal from another communication device other than the communication device, transmit a signal to the processor, or transmit a signal from the processor to another communication device other than the communication device. The processor is configured to implement the method according to the second aspect and any one of the possible implementations of the second aspect by using a logic circuit or executing code instructions. The communication device may be an access network device or may be a chip in the access network device.

[0066] According to an embodiment of the eleventh aspect, the present application provides a communication device including a processor, a storage medium, at least one processor, and an interface circuit. The interface circuit is configured to receive a signal from another communication device other than the communication device, transmit a signal to the processor, or transmit a signal from the processor to another communication device other than the communication device. The processor is configured to implement the method according to the third aspect and any one of the possible implementations of the third aspect by using a logic circuit or executing code instructions. The communication device may be an access network device or may be a chip in the access network device.

[0067] According to an aspect of the twelfth aspect, the present application provides a communication device including a processor, a storage medium, at least one processor, and an interface circuit. The interface circuit is configured to receive a signal from another communication device other than the communication device, transmit a signal to the processor, or transmit a signal from the processor to another communication device other than the communication device. The processor is configured to implement the method according to the fourth aspect and any one of the possible implementations of the fourth aspect by using a logic circuit or executing code instructions. The communication device may be a terminal device or may be a chip in the terminal device.

[0068] According to a thirteenth aspect, the present application provides a computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are executed on a computer, the computer is enabled to perform a method according to the first aspect and any one of the possible implementations of the first aspect.

[0069] According to a fourteenth aspect, the present application provides a computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are executed on a computer, the computer is enabled to perform a method according to the second aspect and any one of the possible implementations of the second aspect.

[0070] According to a fifteenth aspect, the present application provides a computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are executed on a computer, the computer is enabled to perform a method according to the third aspect and any one of the possible implementations of the third aspect.

[0071] According to a sixteenth aspect, the present application provides a computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are executed on a computer, the computer is enabled to perform a method according to the fourth aspect and any one of the possible implementations of the fourth aspect.

[0072] According to a seventeenth aspect, the present application provides a computer program product comprising instructions, which when executed on a computer, enable the computer to perform a method according to the first aspect and any one of the possible implementations of the first aspect.

[0073] According to an eighteenth aspect, the present application provides a computer program product comprising instructions, which when executed on a computer, enables the computer to perform a method according to the second aspect and any one of the possible implementations of the second aspect.

[0074] According to a nineteenth aspect, the present application provides a computer program product comprising instructions, which when executed on a computer, enables the computer to perform a method according to the third aspect and any one of the possible implementations of the third aspect.

[0075] According to a twentieth aspect, the present application provides a computer program product comprising instructions, which when executed on a computer, enable the computer to perform a method according to the fourth aspect and any one of the possible implementations of the fourth aspect.

[0076] It should be understood that the description of technical features, technical solutions, beneficial effects, or similar terms in this application does not imply that all features and advantages can be implemented in any individual embodiment. Conversely, the description of the features or beneficial effects may be understood to mean that at least one embodiment includes the particular technical feature, technical solution, or beneficial effect. Thus, the description of the technical features, technical solutions, or beneficial effects in this specification may not necessarily be specific to the same embodiment. Furthermore, the technical features, technical solutions, and beneficial effects described in the embodiments may be combined in any suitable manner. Those skilled in the art may understand that an embodiment may be implemented without one or more particular technical features, technical solutions, or beneficial effects in a particular embodiment. In other embodiments, additional technical features and beneficial effects may be identified in a particular embodiment that does not reflect all embodiments. [Brief description of the drawings]

[0077] [Figure 1] FIG. 2 is a schematic diagram of a transmission process of an MBS according to the present application; [Diagram 2] FIG. 1 is a diagram of a system architecture of a communication system according to an embodiment of the present application. [Diagram 3] FIG. 2 is a diagram of a system architecture of another communication system according to an embodiment of the present application. [Figure 4] FIG. 2 is a schematic diagram of the architecture of a user plane protocol stack according to an embodiment of the present application; [Diagram 5] 2 is a schematic flowchart of a cell measurement and handover method according to an embodiment of the present application; [Figure 6] 1 is a schematic flowchart of a communication method according to an embodiment of the present application. [Figure 7] 4 is a schematic flowchart of another communication method according to an embodiment of the present application. [Figure 8] FIG. 2 is a schematic diagram of a configuration of an MRB and a DRB according to an embodiment of the present application. [Figure 9]4 is a schematic flowchart of yet another communication method according to an embodiment of the present application. [Figure 10] 4 is a schematic flow chart of yet another communication method according to an embodiment of the present application. [Figure 11] 4 is a schematic flowchart of a further communication method according to an embodiment of the present application; [Figure 12] 1 is a schematic diagram of the structure of a communication device according to an embodiment of the application; [Figure 13] 1 is a schematic diagram of a hardware structure of a communication device according to an embodiment of the present application; [Figure 14] 1 is a schematic diagram of a hardware structure of a communication device according to an embodiment of the present application; [Figure 15] FIG. 2 is a schematic diagram of a hardware structure of a terminal device according to an embodiment of the present application; [Figure 16] FIG. 2 is a schematic diagram of a hardware structure of an access network device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0078] In the description of this application, unless otherwise specified, " / " means "or". For example, A / B may indicate A or B. The term "and / or" in this specification only describes the correspondence between associated objects and indicates that there may be three relationships. For example, A and / or B may represent the following three cases: only A exists, both A and B exist, and only B exists. In addition, "at least one" means one or more, and "multiple" means two or more. Terms such as "first" and "second" do not limit the quantity and execution order, and terms such as "first" and "second" do not indicate an obvious difference.

[0079] It should be noted that in this application, words such as "example," "for example," and the like are used to denote something that provides an example, an illustration, or an explanation. Any embodiment or design scheme described in this application as an "example" or "for example" should not be described as being preferred or having more advantages over another embodiment or design scheme. In particular, the use of words such as "example," "for example," and the like is intended to express the related concept in a particular manner.

[0080] The communication system in the embodiment of the present application includes, but is not limited to, a long term evolution (LTE) system, a 5th-generation (5G) system, a new radio (NR) system, a wireless local area network (WLAN) system, a system to be evolved in the future, or a system that aggregates multiple communication technologies. The 4G system may be referred to as an evolved packet system (EPS). In the 4G system, the core network may be referred to as an evolved packet core (EPC), and the access network may be referred to as a long term evolution (LTE). In the 5G system, the core network may be referred to as a 5GC (5G core), and the access network may be referred to as a new radio (NR). For ease of explanation, the present application is described below by using an example in which the present application is applied to a 5G system. However, it may be understood that the present application is also applicable to a 4G system, a 3rd Generation (3G) system, and the like. This is not limited. For example, the methods provided in the embodiments of the present application may be specifically applied to evolved-universal terrestrial radio access network (E-UTRAN) and next generation-radio access network (NG-RAN) systems.

[0081] The access network device in the embodiment of the present application is a network side entity configured to send a signal, receive a signal, or send a signal and receive a signal. The access network device may be an apparatus deployed in a radio access network (RAN) and providing a wireless communication function to a terminal device, and may be, for example, a TRP, a base station (e.g., evolved NodeB (eNB or eNodeB), next generation node base station (gNB), or next generation eNB (ng-eNB)), various forms of control nodes (e.g., network controllers, or radio controllers (e.g., radio controllers in a cloud radio access network (CRAN) scenario), or road side units (RSUs). Specifically, the access network device may be various forms of macro base stations, micro base stations (also called small cells), relay stations, access points (APs), etc., or may be an antenna panel of a base station. The control node may be connected to multiple base stations and configure resources for multiple terminal devices that fall within the coverage of the multiple base stations. In systems using different radio access technologies (RATs), the names of devices having base station functionality may be different. For example, a base station may be called an eNB or eNodeB in an LTE system, and a gNB in ​​a 5G system or an NR system. The specific names of base stations are not limited in this application. Alternatively, the access network device may be an access network device in a future evolved public land mobile network (PLMN), etc.

[0082] A terminal device in an embodiment of the present application is a user-side entity configured to receive signals, send signals, or receive and send signals. The terminal device is configured to provide one or more of voice services and data connectivity services to a user. A terminal device may also be called user equipment (UE), terminal, access terminal, subscriber unit, subscriber station, mobile station, remote station, remote terminal, mobile device, user terminal, wireless communication device, user agent, or user equipment. The terminal device may be a vehicle-to-everything (V2X) device, such as a smart car (or intelligent car), a digital car, an unmanned car (or driverless car, or pilotless car, or automobile), a self-driving car (or autonomous car), a pure electric vehicle (or Battery EV), a hybrid electric vehicle (HEV), a range extended electric vehicle (REEV), a plug-in hybrid electric vehicle (plug-in HEV, PHEV), or a new energy vehicle. Alternatively, the terminal device may be a device-to-device (D2D) device, such as an electricity meter or a water meter.Alternatively, the terminal device may be a mobile station (MS), a subscriber unit, an unmanned aerial vehicle, an internet of things (IoT) device, a station (ST) in a WLAN, a cellular phone, a smartphone, a cordless phone, a wireless data card, a tablet computer, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA) device, a laptop computer, a machine type communication (MTC) terminal, a handheld device with wireless communication capabilities, a computing device or another processing device connected to a wireless modem, an in-vehicle device, or a wearable device (which may also be referred to as a wearable intelligent device). Alternatively, the terminal device may be a terminal device in a next-generation communication system, for example, a terminal device in a 5G system, a terminal device in a future evolved PLMN, or a terminal device in an NR system.

[0083] The communication method provided in the embodiment of the present application may be applied to the communication system 100 shown in Fig. 2. As shown in Fig. 2, the communication system 100 includes an MBS server 10, a core network device 20, a first access network device 30, a second access network device 40, and a terminal device 50.

[0084] The MBS server 10 is configured to provide an MBS.

[0085] The core network device 20 is configured to receive the MBS from the MBS server and send the MBS to an access network device (the first access network device or the second access network device).

[0086] The first access network device 30 is an access network device (i.e., a source base station) currently accessed by the terminal device 50. The first access network device 30 is configured to provide a network service to the terminal device before the terminal device performs a cell handover. For example, before the cell handover, the first access network device 30 is configured to receive an MBS from the core network device 20 and send the MBS to the terminal device 50.

[0087] The second access network device 40 is an access network device (i.e., a target base station) to which the terminal device 50 should be handed over. The second access network device is configured to provide a network service to the terminal device after the terminal device performs a cell handover. For example, after the cell handover, the second access network device 40 is configured to receive an MBS from the core network device 20 and send the MBS to the terminal device 50.

[0088] The terminal device 50 is configured to communicate with, receive data from, or send data to an access network device. For example, the terminal device 50 is configured to receive an MBS from an access network device.

[0089] In this embodiment of the present application, the first access network device is an access network device that supports a multicast-broadcast transmission mode, and the second access network device is an access network device that does not support a multicast-broadcast transmission mode. The MBS is transmitted between the core network device and the first access network device via an MBS session, and the MBS is transmitted between the core network device and the second access network device via a unicast PDU session. The MBS is transmitted between the first access network device and the terminal device via a multicast radio bearer (MRB), and the unicast service is transmitted between the first access network device and the terminal device via a unicast radio bearer. The unicast service is transmitted between the second access network device and the terminal device via a unicast radio bearer.

[0090] In relation to Figure 2, as shown in Figure 3, the terminal device may be any terminal device having a function of receiving data and / or sending data, such as a mobile phone, a car, or an Internet of Things device shown in Figure 3. In addition, the terminal device may alternatively be a device having a capability of receiving data, such as a public security device not shown in Figure 3. The type of the terminal device is not limited in this application.

[0091] Currently, when a terminal device communicates with an access network device, there is a corresponding protocol stack structure between the terminal device and the access network device, and the terminal device communicates with the access network device based on the protocol stack structure.

[0092] In one example, a user plane protocol stack structure used by a terminal device and an access network device includes a radio resource control (RRC) layer, a service data adaptation protocol (SDAP) layer, a PDCP layer, an RLC layer, and a media access control (MAC) layer. c The IEEE 802.11 standard includes a control (MAC) layer and a physical (PHY) layer. The PHY layer is located at the bottom layer (Layer 1), the MAC layer, the RLC layer, the PDCP layer, and the SDAP layer belong to the second layer (Layer 2), and the RRC layer belongs to the third layer (Layer 3).

[0093] As shown in FIG. 4, for the user plane protocol stack for transmitting MBS, the PHY is located at the bottom layer, the MAC layer is located above the PHY layer, the RLC layer is located above the MAC layer, the PDCP layer is located above the RLC layer, and the SDAP layer is located above the PDCP layer.

[0094] The MBS is usually a service sent by an access network device to a terminal device. As a result, when the MBS is sent, the sending procedure of the MBS is as follows:

[0095] First, the MBS arrives at the SDAP layer of the first access network device, is mapped by the SDAP layer and then sent to the corresponding PDCP entity, is processed by the PDCP layer of the first access network device and then sent to the RLC layer and the MAC layer, is correspondingly processed and then sent from the PHY layer, and is sent to the terminal device via the air interface.

[0096] The protocol layer of the terminal device sequentially performs corresponding processing on the data packets in a processing order opposite to that of the first access network device.

[0097] At the first access network device side and the terminal device side, the processing of data packets in layers can be visually combined to be called a radio bearer. Each data in the radio bearer needs to be processed in each layer, and each layer has a corresponding functional entity to perform a corresponding function, for example, a PDCP entity in the PDCP layer.

[0098] Each radio bearer configuration includes one PDCP entity, and a radio bearer configuration is associated with at least one RLC entity, and each RLC entity corresponds to one logical channel.

[0099] The protocol stack structure between the terminal device and the access network device is described above.

[0100] In current mobile communication systems, multiple cells may cover the same location. When a terminal device is located at the same location covered by multiple cells, the terminal device needs to select to access the cell with the strongest signal strength. In this way, the terminal device transmits service data on the cell with the strongest signal strength, improving the data transmission quality of the terminal device.

[0101] In the process of a terminal device moving, the strength of the signals received by the terminal device from each cell changes continuously.

[0102] For example, when a terminal device is moving away from a currently accessed cell (denoted as cell A), the strength of the signal received by the terminal device from cell A decreases continuously. If the terminal device continues to transmit a service on cell A when the strength of the signal received by the terminal device from cell A decreases to a certain value, the service may experience, for example, disruptions, congestion, or even disconnections.

[0103] In order to ensure the transmission quality of service of the terminal device, in the mobility process, if the terminal device determines that the signal strength of a neighboring cell (denoted as cell B) of cell A is greater than the signal strength of cell A, the terminal device needs to report the event (specifically, the signal strength of cell B is greater than the signal strength of cell A) to the access network device, and trigger the access network device to initiate a handover procedure, so as to handover the terminal device from cell A to cell B.

[0104] In this way, the terminal device can always continue to transmit its service on the cell with stronger signal strength, and ensure the transmission quality of the service of the terminal device.

[0105] As shown in FIG. 5, currently, the method for performing cell measurement and handover by a terminal device and a first access network device includes the following steps 1 to 10.

[0106] Step 1: A terminal device accesses a first access network device.

[0107] The first access network device may be cell A.

[0108] In a possible implementation, the terminal device accessing the access network device may be implemented as follows: The terminal device camps on cell A and enters a connected state.

[0109] Step 2: The first access network device sends the measurement configuration parameters to the terminal device. In response, the terminal device receives the measurement configuration parameters from the first access network device.

[0110] In a possible implementation, the measurement configuration parameter is carried in an RRC Reconfiguration message sent by the first access network device to the terminal device. In other words, the RRC Reconfiguration message sent by the first access network device to the terminal device includes a measurement configuration parameter (MeasConfig).

[0111] The measurement configuration parameters recorded in this embodiment of the present application include at least one of the following information: measurement frequency / cell information, reporting threshold configuration, filtering parameter configuration, timer period configuration, etc.

[0112] The measurement frequency / cell information indicates the cell to be measured and the frequency corresponding to this cell. The measurement frequency / cell information includes information about the cell currently accessed by the terminal device. Alternatively, the measurement frequency cell information may include only information about the frequency that needs to be measured. In this case, the information about the currently accessed cell may be indicated by an RRC reconfiguration message.

[0113] The reporting threshold configuration indicates a condition under which the terminal device sends a measurement report to the first access network device. In other words, the reporting threshold configuration indicates a condition under which the terminal device determines a measurement report based on a measurement result and sends the measurement report to the first access network device.

[0114] The filtering coefficients are used to filter the cell signal strength currently measured by the terminal device and the cell measurement results determined by the terminal device during previous cell measurements to determine the cell measurement results.

[0115] Step 3: The terminal device measures the signal strength of the frequency or cell based on the measurement configuration parameters, and determines the measurement result.

[0116] For example, the measurement configuration parameters may indicate that the cells that need to be measured include cell A and cell B.

[0117] The terminal device initiates a physical (PHY) layer to measure the signal strength of cell A based on the frequency setting or cell setting information in the measurement configuration parameters, and the PHY layer of the terminal device sends the signal strength of cell A to the RRC layer of the terminal device. The RRC layer of the terminal device determines the measurement result of cell A based on the signal strength of cell A, the previous measurement result of cell A, and the filtering coefficient.

[0118] The terminal device initiates a physical layer to measure the signal strength of cell B based on the frequency setting or cell setting information in the measurement configuration parameters, and the PHY layer of the terminal device sends the signal strength of cell B to the RRC layer of the terminal device. The RRC layer of the terminal device determines the measurement result of cell B based on the signal strength of cell B, the previous measurement result of cell B, and the filtering coefficient.

[0119] Specifically, for cell A, the terminal device performs the following steps 3.1 to 3.3, thereby determining the measurement result of cell A.

[0120] Step 3.1: The terminal device starts the physical (PHY) layer to measure the reference signal of cell A to determine the current signal strength of cell A.

[0121] The signal strength of cell A includes at least one of, but is not limited to, a reference signal received power (RSRP) value, a reference signal received quality (RSRQ) value, a signal to interference plus noise ratio (SINR) value, and a received signal strength indicator (RSSI).

[0122] Step 3.2: The terminal device determines the previous measurement results of cell A.

[0123] The previous measurement result of cell A is determined based on the signal strength and filtering parameters of cell A previously determined by the terminal device. The specific implementation of determining the previous measurement result is similar to the method for determining the current measurement result of cell A by the terminal device. The details will not be described again in this application.

[0124] Step 3.3: The terminal device determines the measurement result of cell A according to Equation 1 and based on the current signal strength of cell A and the previous measurement result of cell A.

[0125] Please note that when the terminal device measures the signal strength of cell A for the first time, the terminal device directly uses the measurement result in step 3.1 as the measurement result of cell A, and does not need to determine the final measurement result according to the method recorded in steps 3.1 to 3.3.

[0126] For cell B, the terminal device determines the measurement results for cell B in a manner similar to steps 3.1 to 3.3.

[0127] Step 4: The terminal device determines a measurement report based on the measurement result.

[0128] Specifically, in step 3, the RRC layer of the terminal device determines the measurement result of each cell. The RRC layer of the terminal device evaluates the measurement result of each cell and determines whether the current measurement result meets one of the measurement events that need to be reported. If the current measurement result meets one of the measurement events that need to be reported, the RRC layer of the terminal device generates a corresponding measurement report and sends the measurement report to the first access network device.

[0129] In a possible implementation, the measurement report is used to report measurement events to an access network device.

[0130] Example 1: Measurement events that need to be reported and are determined by the terminal device include:

[0131] A1: The measurement result of the serving cell is greater than the threshold a1.

[0132] A2: The measurement result of the serving cell is less than the threshold a2.

[0133] A3: The measurement result of the neighboring cell is greater than the measurement result of the serving cell plus an offset.

[0134] A4: The measurement result of the adjacent cell is greater than threshold a3.

[0135] A5: The measurement result of the serving cell is less than the threshold a4, and the measurement result of the neighboring cell is greater than the threshold a5.

[0136] A6: The measurement result of the neighboring cell is greater than the measurement result of the SCell plus an offset.

[0137] B1: The measurement result of the inter-RAT cell is greater than the threshold a6.

[0138] B2: The measurement result of the inter-RAT cell is greater than threshold a7, and the measurement result of the SPCell is smaller than threshold a8.

[0139] The serving cell is cell A, and the neighboring cell is cell B. The terminal device determines whether the measurement results of cell A and cell B satisfy a measurement event that needs to be reported based on the measurement results of cell A and cell B. If the measurement results of cell A and cell B satisfy a measurement event that needs to be reported, the terminal device generates a measurement report corresponding to this event.

[0140] It can be understood that the events that need to be reported can further include other types of events, which is not limited in this application.

[0141] It should be noted that the terminal device may determine the measurement events that need to be reported based on the MeasIdList in the measurement configuration sent by the access network device. The MeasIdList is used to associate frequency / cell information with the measurement events that need to be reported and the measurement reporting conditions.

[0142] For example, the measurement event that needs to be reported by the terminal device includes an A3 event. When the terminal device determines that the current measurement result satisfies the A3 event, the terminal device generates a measurement report corresponding to the A3 event.

[0143] It should be noted that the measurement report generated by the terminal device usually includes only one measurement event that needs to be reported. When there are multiple measurement events that need to be reported and the terminal device determines that the current measurement result satisfies the multiple measurement events that need to be reported, the terminal device generates a corresponding measurement report for each measurement event that needs to be reported and sends the measurement reports to the access network device one by one.

[0144] Step 5: The terminal device sends a measurement report to the first access network device, and correspondingly, the terminal device receives the measurement report from the first access network device.

[0145] Step 6: The first access network device determines a second access network device based on the measurement report, and sends a handover request to the second access network device. In response, the second access network device receives a handover request from the first access network device.

[0146] The second access network device is the access network device to which the terminal device needs to be handed over.

[0147] It should be noted that the first access network device is also called the source base station and corresponds to cell A recorded in step 3. The second access network device is also called the target base station and corresponds to cell B recorded in step 3.

[0148] Step 7: The second access network device sends handover request acknowledgment information (Handover Request ACK) to the first access network device. In response, the first access network device receives handover request acknowledgment information from the second access network device.

[0149] In a possible implementation, after the second access network device receives a handover request from the first access network device, the second access network device determines the quantity of device connections, time-frequency resource allocation, load, etc. of the second access network device. When the second access network device determines that the terminal device can be allowed to access the second access network device, the second access network device sends acknowledgement information of the handover request to the first access network device.

[0150] In one example, the handover request acknowledgement information includes at least one of a cell radio network temporary identifier (C-RNTI) and a security algorithm of the second access network device.

[0151] Step 8: The first access network device sends an RRC reconfiguration message to the terminal device. In response, the terminal device receives an RRC reconfiguration message from the first access network device.

[0152] The RRC reconfiguration message includes the acknowledgement information of the handover request sent by the second access network device to the first access network device. In other words, in step 8, the first access network device may send the acknowledgement information of the handover request sent by the second access network device to the first access network device to the terminal device in a transparent transmission mode.

[0153] In a possible implementation, when at least one of the first access network device and the second access network device is an access network device in an NR system, the RRC reconfiguration message includes related information of the second access network device and at least one of the configuration parameters required for the terminal device to access the second access network device.

[0154] Specifically, the RRC reconfiguration message includes at least one of a physical cell identifier (PCI) of cell B, frequency information of cell B (e.g., the frequency or other frequency information of cell B), a C-RNTI assigned to the terminal device by cell B, and random access channel (RACH) resource information required to access cell B (e.g., dedicated RACH resources and / or common RACH resources).

[0155] Step 9: The terminal device initiates random access to the second access network device.

[0156] It should be noted that when the terminal device currently initiates random access to the second access network device, the terminal device needs to disconnect from the first access network device. Before the terminal device successfully accesses the second access network device, the transmission of data sent by the terminal device is temporarily interrupted.

[0157] Step 10: After the random access is successful, the terminal device sends RRC reconfiguration completion information to the second access network device.

[0158] According to steps 1 to 10, the terminal device can complete the cell measurement and cell handover.

[0159] In current cell handover scenarios, there are scenarios where a first access network device supports a multicast / broadcast transmission mode and a second access network device does not support the multicast / broadcast transmission mode.

[0160] In this scenario, when the MBS is being transmitted between the terminal device and the first access network device, after the terminal device is handed over to the second access network device, the terminal device cannot continue to receive the MBS from the second access network device in the multicast broadcast transmission mode because the second access network device does not support the multicast broadcast transmission mode, and as a result, the service continuity of the MBS cannot be guaranteed.

[0161] In order to solve the aforementioned technical problems, the present application provides a communication method for ensuring service continuity of an MBS when a terminal device is handed over from a first access network device that supports a multicast / broadcast transmission mode to a second access network device that does not support the multicast / broadcast transmission mode.

[0162] The method includes: after the first access network device receives the measurement report of the terminal device, the first access network device determines whether the second access network device supports a multicast / broadcast transmission mode. When the second access network device does not support the multicast / broadcast transmission mode, the first access network device instructs the terminal device to configure a first radio bearer for carrying the MBS as a second radio bearer for carrying a unicast service. Correspondingly, the terminal device configures the first radio bearer as a second radio bearer. Then, the MBS is transmitted between the terminal device and the first access network device via the second radio bearer.

[0163] In this way, the MBS is transmitted between the terminal device and the first access network device in a unicast mode. Therefore, in the process in which the terminal device is subsequently handed over to the second access network device, the first access network device and the second access network device directly switch the transmitted MBS to the second access network device in a manner of switching the current unicast service. This solves the interruption of the MBS caused by the second access network device not supporting the multicast / broadcast transmission mode.

[0164] The communication method provided in this embodiment of the present application is applied to the communication system shown in Figure 2. As shown in Figure 6, the communication method includes the following steps:

[0165] S600: A first access network device sends first indication information to a terminal device. In response, the terminal device receives the first indication information from the first access network device.

[0166] The first indication information instructs the terminal device to configure the first radio bearer as a second radio bearer, where the first radio bearer is a multicast radio bearer and the second radio bearer is a unicast radio bearer.

[0167] It should be noted that the first access network device is an access network device that supports a multicast broadcast transmission mode. Before sending the first indication information, the first access network device receives a measurement report from the terminal device. The measurement report is used to trigger the first access network device to handover the terminal device to the second access network device. The second access network device is an access network device that does not support a multicast broadcast transmission mode.

[0168] In a possible implementation, the first indication information specifically indicates at least one of the following information of the second radio bearer: PDCP setting information, RLC setting information, security setting information, and an identifier of the second radio bearer.

[0169] The terminal device may determine that the currently configured second radio bearer is configured based on the first radio bearer based on the identifier of the second radio bearer being the same as the identifier of the first radio bearer.

[0170] In another possible implementation, the second radio bearer still uses at least one of the following configuration information of the first radio bearer: PDCP configuration information, and PTP RLC configuration information. The PDCP entity corresponding to the second radio bearer still uses the transmission status and transmission parameters, which are the transmission window of the PDCP entity corresponding to the first radio bearer. The transmission status and transmission parameters of the transmission window include at least one of the currently transmitted data packet with the maximum SN, the successfully transmitted data packets, the unsuccessfully transmitted data packets, the size of the transmission window, the running status of the timer associated with the transmission window, etc.

[0171] Specifically, when the second radio bearer still uses at least one of the PDCP setting information and the PTP RLC setting information of the first radio bearer, the first indication information includes a first identifier, which instructs the terminal device to still use at least one of the PDCP setting information and the PTP RLC setting information.

[0172] For example, the first indication information includes two bits, which respectively indicate whether the PDCP configuration information and / or the PTP RLC configuration information of the first radio bearer are still used. When the value of the bit is 0, it indicates that the PDCP configuration information and / or the PTP RLC configuration information of the first radio bearer are still used. When the value of the bit is 1, it indicates that the PDCP configuration information and / or the PTP RLC configuration information of the first radio bearer are not still used.

[0173] In one example, when the value of the two bits is “00”, the first indication information instructs the terminal device to still not use both the PDCP setting information of the first radio bearer and the PTP RLC setting information of the first radio bearer.

[0174] When the value of the 2 bits is “01”, the first indication information instructs the terminal device to still not use the PDCP setting information of the first radio bearer, but to still use the PTP RLC setting information of the first radio bearer.

[0175] When the value of the 2 bits is “10”, the first indication information instructs the terminal device to still use the PDCP setting information of the first radio bearer and not still use the PTP RLC setting information of the first radio bearer.

[0176] When the value of the two bits is “11”, the first indication information instructs the terminal device to still use both the PDCP setting information of the first radio bearer and the PTP RLC setting information of the first radio bearer.

[0177] For another example, the first indication information indicates that the current configuration is a special type of configuration, and it is agreed in the protocol that after receiving this type of configuration, the terminal device uses at least one of the PDCP setting information and the PTP RLC setting information of the previous radio bearer.

[0178] S601: A first access network device sends an MBS to a terminal device via a second radio bearer. In response, the terminal device receives the MBS sent by the first access network device via the second radio bearer.

[0179] In a possible implementation, the first radio bearer is a MBS radio bearer (MRB), and the second radio bearer is a data radio bearer (DRB). In the following, an example in which the first radio bearer is a MRB and the second radio bearer is a DRB is used for explanation.

[0180] After S601, the terminal device, the first access network device, and the second access network device may perform cell handover according to the solution recorded in steps 6 to 10 of Figure 5. After being handed over to the second access network device, the terminal device transmits the MBS in a unicast mode.

[0181] According to the aforementioned technical solution, when a terminal device needs to be handed over from a first access network device supporting a multicast / broadcast transmission mode to a second access network device not supporting a multicast / broadcast transmission mode, the first access network device configures a first radio bearer currently used to carry MBS between the first access network device and the terminal device as a second radio bearer used to carry unicast services, and the first access network device sends the MBS to the terminal device in a unicast mode via the second radio bearer.

[0182] In this way, the MBS is transmitted between the terminal device and the first access network device in unicast mode. Therefore, in the process of the terminal device being subsequently handed over to the second access network device, the first access network device and the second access network device directly switch the transmitted MBS to the second access network device in a manner of switching the current unicast service. This solves the interruption of the MBS caused by the second access network device not supporting the multicast / broadcast transmission mode.

[0183] In a possible implementation, as shown in Fig. 7 in conjunction with Fig. 6, before S600, the method provided in this embodiment of the present application further includes the following S700 to S703. Specific descriptions are given below.

[0184] S700: A core network device sends an MBS to a first access network device. In response, the first access network device receives the MBS from the core network device.

[0185] Specifically, after the terminal device accesses the first access network device, if the MBS needs to be transmitted between the terminal device and the first access network device, before the MBS is transmitted, the core network device initiates an MBS session or an MBS flow establishment / modification request, so that a transmission channel used to transmit the MBS is established between the core network device and the first access network device. The core network device transmits the MBS to the first access network device through the established transmission channel.

[0186] A first radio bearer (MRB) is established between the first access network device and the terminal device, and the MBS is transmitted between the first access network device and the terminal device via the first radio bearer.

[0187] S701: A terminal device sends a measurement report to a first access network device.

[0188] It should be noted that in this embodiment of the present application, before triggering the terminal device to perform cell handover, the first access network device must first configure the first radio bearer as the second radio bearer and instruct the terminal device to send MBS via the second radio bearer. Thus, the period required by the terminal device to perform cell handover increases. In order to avoid a handover failure or a long service interruption period of the terminal device caused by an excessively long period for the terminal device to perform cell handover, the present application further provides a method that can trigger the terminal device to report a measurement report in advance, so that the terminal device has a sufficient period to perform cell handover.

[0189] In a possible implementation, the terminal device may trigger and report a measurement report by using a new measurement event, which is used to enable the terminal device to trigger and report a measurement report in advance.

[0190] In one example, relating to Example 1, the new measurement event includes at least one of the following:

[0191] E1: The measurement result of the serving cell is greater than threshold b1.

[0192] E2: The measurement result of the serving cell is less than threshold b2.

[0193] E3: The neighbor cell measurement result plus c is greater than the serving cell measurement result plus an offset.

[0194] E4: The measurement result of the neighboring cell is greater than threshold b3.

[0195] E5: The measurement result of the serving cell is less than the threshold b4, and the measurement result of the neighboring cell is greater than the threshold b5.

[0196] E6: The measurement result of the neighboring cell plus d is greater than the measurement result of the SCell plus an offset.

[0197] F1: The measurement result of the inter-RAT cell is greater than the threshold b6.

[0198] F2: The measurement result of the inter-RAT cell is greater than the threshold b7, and the measurement result of the SPCell is smaller than the threshold b8.

[0199] a1 is greater than b1, a2 is less than b2, a3 is greater than b3, a4 is less than b4, a5 is greater than b5, a6 is greater than b6, a7 is greater than b7, a8 is less than b8, and both c and d are greater than 0.

[0200] Based on the new measurement event, the terminal device can trigger and report a measurement report in advance, so that the terminal device has enough time to configure the first radio bearer as the second radio bearer and perform a cell handover, which reduces the probability of handover failure or the service interruption period of the terminal device.

[0201] The introduction of new measurement events is optional. Alternatively, the terminal device may trigger and report measurement reports based on existing measurement events configured for handover, and the first access network device may decide to first configure the MRB as a DRB before performing handover based on existing measurement mechanisms and whether the target base station supports multicast / broadcast transmission modes.

[0202] S702: The first access network device determines a second access network device based on the measurement report.

[0203] S703: The first access network device determines whether the second access network device supports a multicast / broadcast transmission mode.

[0204] In a possible implementation, the method for determining by the first access network device whether the first access network device supports the multicast broadcast transmission mode includes at least the following three schemes: Scheme 1: The first access network device determines whether the second access network device supports the multicast broadcast transmission mode by performing a signaling interaction with the second access network device; Scheme 2: The first access network device determines whether the second access network device supports the multicast broadcast transmission mode via an operation administration and maintenance (OAM) system; Scheme 3: The first access network device determines whether the second access network device supports the multicast broadcast transmission mode based on past handover records.

[0205] Below, Scheme 1, Scheme 2, and Scheme 3 are described separately in detail.

[0206] Method 1: A first access network device determines whether a second access network device supports a multicast / broadcast transmission mode by performing a signaling interaction with the second access network device.

[0207] In a possible implementation, method 1 may be implemented in the following steps a to c.

[0208] Step a: the first access network device sends request information to the second access network device, and in response, the second access network device receives the request information from the first access network device.

[0209] The request information requests inquiring whether the second access network device supports a multicast / broadcast transmission mode.

[0210] Step b: The second access network device sends response information to the first access network device. In response, the first access network device receives response information from the second access network device.

[0211] The response information indicates whether the second access network device supports a multicast or broadcast transmission mode.

[0212] In one example, one bit in the response information indicates whether the second access network device supports a multicast / broadcast transmission mode.

[0213] When the value of the bit is "0", the response information indicates that the second access network device does not support the multicast / broadcast transmission mode.

[0214] When the value of the bit is "1", the response information indicates that the second access network device supports the multicast / broadcast transmission mode.

[0215] Step c: The first access network device determines, based on the response information, whether the second access network device supports a multicast / broadcast transmission mode.

[0216] With reference to the previous example, the first access network device determines whether the second access network device supports a multicast / broadcast transmission mode based on the value of the bit in the response information.

[0217] Method 2: The first access network device determines, through an OAM system, whether the second access network device supports a multicast / broadcast transmission mode.

[0218] The OAM system is an OAM system to which the second access network device belongs, and the OAM system stores configuration information of the second access network device.

[0219] Method 3: The first access network device determines whether the second access network device supports a multicast / broadcast transmission mode based on past handover records.

[0220] Specifically, when the terminal device is handed over from the first access network device to the second access network device for the first time, the first access network device may determine whether the second access network device supports the multicast / broadcast transmission mode in the manner recorded in Scheme 1 or Scheme 2. Then, the first access network device stores a past handover record. The past handover record may represent information about whether the second access network device supports the multicast / broadcast transmission mode.

[0221] During the next handover, the first access network device determines whether the second access network device supports a multicast / broadcast transmission mode based on the stored past handover records.

[0222] It should be noted that after S703, if the first access network device determines that the second access network device does not support the multicast / broadcast transmission mode, the first access network device and the terminal device execute S600 and S601.

[0223] If the first access network device determines that the second access network device supports the multicast-broadcast transmission mode, the first access network device, the second access network device and the terminal device directly perform cell handover according to steps 6 to 10 recorded in FIG. 5.

[0224] In a possible implementation, after S600, if the terminal device configures the first radio bearer as the second radio bearer, the session between the first access network device and the core network device may be switched from the original MBS session to a unicast session (case 1), or the MBS session is still maintained between the first access network device and the core network device (case 2).

[0225] Below, Case 1 and Case 2 are described separately in detail.

[0226] Case 1: An MBS session between the first access network device and the core network device is switched to a unicast session, and the MBS is transmitted between the first access network device and the core network device via the unicast session.

[0227] As shown in FIG. 7, in case 1, after S600, the method further includes S704.

[0228] S704: The first access network device sends second indication information to the core network device. In response, the core network device receives the second indication information from the first access network device.

[0229] The second indication information instructs the core network device to send the MBS to the first access network device via a unicast session or a unicast quality of service flow corresponding to the terminal device.

[0230] In a possible implementation, the second indication information further indicates a data packet serial number, where the data packet serial number is the data packet serial number of the first data packet of the MBS sent by the core network device through the unicast session or the unicast quality of service flow.

[0231] The data packet serial number may be a General Packet Radio Service Tunneling Protocol-User Plane (GPRS Tunneling Protocol-U, GTP-U) serial number (SN) or a QoS Flow Identifier (QoS Flow ID, QFI) SN of the data packet.

[0232] Case 2: The MBS session is still maintained between the first access network device and the core network device for transmitting the MBS.

[0233] In case 2, after receiving the MBS transmitted by the core network device over the MBS session, the first access network device maps data of the MBS to a second radio bearer for transmission.

[0234] In a possible implementation, after the terminal device receives the first indication information, the terminal device configures the first radio bearer as the second radio bearer. The following describes in detail the process of the terminal device configuring the first radio bearer as the second radio bearer. The first indication information may be an RRC message sent by the first access network device to the terminal device. The RRC message instructs the terminal device to reconfigure the MRB as a DRB.

[0235] 8, the MRB before reconfiguration includes at least one of a PDCP configuration, a service identifier, and a radio bearer identifier. In addition, the MRB configuration is associated with a PTP RLC configuration and a PTM RLC configuration, and is used for PTP and PTM transmission of data packets separately.

[0236] The reconfigured DRB includes at least one of a PDCP configuration, a security configuration, a radio bearer identifier, and an associated PTP RLC configuration.

[0237] In the process of configuring the MRB as a DRB, the terminal device may know to delete the temporary multicast group identifier (TMGI) in the MRB configuration and add the security configuration to the MRB. The radio bearer identifier of the DRB after reconfiguration is the same as that of the MRB before reconfiguration.

[0238] Correspondingly, the first indication information includes at least one of the following information: PDCP configuration information, RLC configuration information, security configuration information, and identifier information of the DRB. Detailed descriptions are provided separately below.

[0239] (a). The PDCP setting information is used to configure the PDCP of the DRB. The first indication information may include the PDCP setting information or may not include the PDCP setting information.

[0240] When the first indication information does not include PDCP setting information, the terminal device determines to still use the PDCP configuration in the MRB as the PDCP configuration of the DRB. In this case, the terminal device determines to reserve the PDCP configuration in the MRB as the PDCP configuration of the DRB.

[0241] When the first indication information includes PDCP setting information, the terminal device configures the PDCP configuration of the DRB according to the PDCP setting information. In this case, the terminal device releases the PDCP configuration in the MRB, and performs the PDCP configuration according to the PDCP setting information in the first indication information.

[0242] (b) The RLC configuration information indicates configuration information of an RLC associated with a DRB. The first indication information may include the RLC configuration information or may not include the RLC configuration information.

[0243] When the first indication information does not include RLC setting information, the terminal device determines to still use the PTP RLC in the MRB as the RLC configuration of the DRB. In this case, the terminal device determines to reserve the PTP RLC in the MRB as the RLC configuration of the DRB.

[0244] When the first indication information includes RLC setting information, the terminal device configures the RLC configuration of the DRB according to the RLC setting information in the first indication information. In this case, the terminal device releases the RLC configuration in the MRB, and configures the RLC configuration of the DRB according to the RLC setting information in the first indication information.

[0245] (c) The security setting information is used to configure a security configuration of the DRB. In the process of transmitting a data packet, the PDCP entity performs security processing on the data packet based on the security configuration to improve data security.

[0246] (d) The DRB identifier indicates the identifier of the configured DRB.

[0247] It should be noted that after the terminal device configures the MRB as a DRB, in order to avoid loss of data packets of the MRB service, the first access network device determines that the PDCP entity corresponding to the second radio bearer still uses the transmission status and transmission parameters of the transmission window of the PDCP entity corresponding to the first radio bearer.

[0248] Specifically, after the first access network device determines that the terminal device configures the MRB as a DRB, the first access network device and the terminal device do not re-establish a new PDCP entity, but still use the PDCP entity corresponding to the MRB for the DRB. In addition, the first access network device and the terminal device do not initialize or reset the transmission status and transmission parameters of the transmission window of the PDCP entity corresponding to the MRB.

[0249] It should be noted that after the first access network device determines that the terminal device configures the MRB as a DRB, the first access network device and the terminal device may alternatively re-establish a PDCP entity, in which case the transmission status and transmission parameters of the transmission window of the re-established PDCP entity need to be initialized or reset.

[0250] In this case, in order to reduce the loss of data packets, the first access network device needs to perform redundant transmission.

[0251] For example, if the first access network device determines that it will send data packet #10 to the terminal device before the MRB is configured as a DRB, after the MRB is configured as a DRB, the first access network device will start transmitting from a data packet (e.g., data packet #5) before data packet #10 to reduce data packet loss.

[0252] According to the aforementioned technical solution, the embodiment of the present application provides a method for configuring the MRD as a DRB by the terminal device before the terminal device performs cell handover, and then transmitting the MBS between the first access network device and the terminal device in unicast mode. Then, the terminal device can perform the cell handover according to the existing handover procedure. In this case, the MBS is sent in unicast mode. Therefore, after the MBS is switched to the second access network device, the MBS can still be transmitted in unicast mode. This avoids the problem that the service continuity of the MBS cannot be guaranteed after the cell handover.

[0253] In addition, an embodiment of the present application further provides a communication method for transmitting an MBS between a first access network device and a terminal device in a multicast mode before handover. After handover, the MBS is transmitted between the terminal device and a second access network device in a unicast mode. The first access network device sends the MBS that is not sent in the unicast mode to the second access network device.

[0254] As shown in Figure 9, the communication method includes S900 to S903. A detailed description is provided below.

[0255] S900: The first access network device receives third indication information.

[0256] The third indication information indicates a correspondence relationship between the unicast quality of service flow and the MBS quality of service flow.

[0257] The third indication information may be carried in the MBS context information sent by the core network device to the first access network device. For example, when an MBS session or an MBS flow is established, the core network device sends the third indication information to the first access network device by using the MBS context information.

[0258] The third indication information includes at least one of a flow identifier of a unicast quality of service flow corresponding to the MBS quality of service flow and a QoS parameter of the unicast quality of service flow.

[0259] The flow identifier of the unicast quality of service flow may be represented via an identifier of the PDU session of the unicast quality of service flow or an identifier of the flow identifier of the unicast quality of service flow.

[0260] In a possible implementation, the third indication information is the indication information sent by the core network device to the second access network device. The time when the core network device sends the third indication information to the first access network device may be before the terminal device sends a measurement report to the first access network device, or may be after the terminal device sends a measurement report to the first access network device, or may be the same as the time when the terminal device sends a measurement report to the first access network device. This is not limited in the present application.

[0261] In another possible implementation, the third indication information further indicates a correspondence relationship between the MBS session and the unicast session, which is not limited in this application.

[0262] S901: The first access network device maps an MBS quality of service flow to a unicast quality of service flow in a handover process according to third indication information.

[0263] S902: The first access network device forwards the unicast quality of service flow to the second access network device.

[0264] Specifically, a data transmission channel is established between a first access network device and a second access network device. Because the second access network device does not support a multicast / broadcast transmission mode, the MBS quality of service flow cannot be identified. Therefore, the first access network device maps the MBS quality of service flow to a unicast quality of service flow. Then, the first access network device transmits the unicast quality of service flow to the second access network device via the established data transmission channel.

[0265] S903: The second access network device sends the MBS to the terminal device through a unicast radio bearer.

[0266] It should be noted that the unicast radio bearer between the second access network device and the terminal device is the unicast radio bearer established in the handover process.

[0267] When the second access network device sends the MBS to the terminal device, the generated identifier of the unicast quality of service flow may be determined based on the correspondence indicated by the third indication information.Details are not described again in this specification.

[0268] In relation to FIG. 9, as shown in FIG. 10, S901 may be specifically implemented by S1000 to S1007.

[0269] S1000: The core network device sends the MBS to the first access network device. In response, the first access network device receives the MBS from the core network device. It should be noted that the specific implementation of S1000 is similar to that of S700. The details are not described again in this application.

[0270] S1001: A terminal device sends a measurement report to a first access network device.

[0271] It should be noted that the specific implementation of S1001 is similar to that of S701, and the details will not be described again in this application.

[0272] S1002: The first access network device determines a second access network device based on the measurement report.

[0273] It should be noted that the specific implementation of S1002 is similar to that of S702, and the details will not be described again in this application.

[0274] S1003: The first access network device sends a handover request to the second access network device. In response, the second access network device receives a handover request from the first access network device.

[0275] The handover request may include relevant information of the MBS.

[0276] In one example, the handover request includes MBS context information (MBS info).

[0277] S1004: The second access network device generates first configuration information.

[0278] The first configuration information instructs the terminal device to perform a configuration based on the configuration information of the second access network.

[0279] In a possible implementation, the first configuration information includes all configuration information used by the second access network device for cell handover and data transmission with the terminal device.

[0280] Specifically, after the second access network device receives a handover request from the first access network device, the second access network device cannot identify the MBS information in the handover request because the second access network device does not support the multicast / broadcast transmission mode.

[0281] In this case, the second access network device determines that the setting information between the first access network and the terminal device includes setting information that cannot be identified by the second access network device. In order to enable the terminal device to perform a configuration based on the setting information of the second access network device, the second access network device generates first setting information, so that the terminal device can perform a configuration based on the first setting information.

[0282] In one example, the first configuration information may be a complete config (full configuration) and instructs the terminal device to perform a complete configuration based on the configuration information of the second access network device instead of performing a delta config (incremental configuration) based on the configuration information of the second access network device.

[0283] S1005: The second access network device sends a handover request acknowledgement information (Handover Request ACK) to the first access network device. In response, the first access network device receives a handover request acknowledgement information from the second access network device.

[0284] The acknowledgement information of the handover request includes the first configuration information.

[0285] S1006: The first access network device sends a handover command to the terminal device. In response, the terminal device receives a handover command from the first access network device.

[0286] The handover command includes the first configuration information.

[0287] After the terminal device receives the handover command, the terminal device identifies the first setting information in the handover command, and performs configuration according to the setting information of the second access network device written in the first setting information, and is handed over to the second access network device.

[0288] It should be noted that in the process in which the terminal device performs configuration based on the setting information of the second access network device, the terminal device establishes a unicast radio bearer between the terminal device and the second access network device, whereby the second access network device subsequently transmits data to the terminal device via the unicast radio bearer.

[0289] S1007: The first access network device maps the MBS quality of service flow to a unicast quality of service flow based on the third indication information.

[0290] Specifically, the first access network device is between the MBS quality of service flow and the unicast quality of service flow, and maps the MBS quality of service flow to the unicast quality of service flow based on the correspondence indicated by the third indication information.

[0291] In a possible implementation, the third indication information indicates a mapping relationship between an MBS quality of service flow and an identifier of a unicast quality of service flow.

[0292] After the first access network device determines the identifier of the unicast quality of service flow corresponding to the MBS quality of service flow, the first access network device replaces the flow identifier in the data packet header of the MBS quality of service flow with the flow identifier of the corresponding unicast quality of service flow to obtain the unicast quality of service flow. The first access network device sends the unicast quality of service flow to the second access network device via the established data transmission channel.

[0293] As shown in FIG. 10, after S902, the method further includes the following steps.

[0294] S1008: The second access network device sends a path switch request message to the core network device.

[0295] The path switch request requests the core network device to switch the transmission path of the MBS from the first access network device to the second access network device.

[0296] The reroute request does not include any information related to the MBS.

[0297] S1009: The core network device sends the MBS to the second access network device via a unicast session or a unicast quality of service flow.

[0298] Specifically, after receiving a path switch request, the core network device determines that the path requested to be switched is a transmission path of the MBS, and the path switch request does not include related information of the MBS.

[0299] As a result, the core network device determines that the second access network device does not support the multicast / broadcast transmission mode, and sends data packets of the MBS to the second access network device in the form of a unicast session or a unicast quality of service flow.

[0300] According to the above technical solution, before the terminal device is handed over to the second access network device, the first access network device and the terminal device continue to send MBS in multicast mode. In the process in which the terminal device performs cell handover, the first access network device instructs the terminal device to send MBS using the second access network in unicast mode. After the handover, the MBS is sent between the terminal device and the second access network device in unicast mode. The first access network device sends the MBS that is not sent in unicast mode to the second access network device.

[0301] In this way, it can be ensured that the terminal device transmits the MBS in unicast mode after being handed over to the second access network device. The method ensures that the terminal device can still transmit the MBS correctly after being handed over to the second access network device. In addition, the handover procedure is similar to the existing handover procedure, is simple to implement, and can ensure the continuity of receiving the MBS by the terminal device.

[0302] The foregoing describes two methods for sending an MBS to a terminal device in unicast mode by the second access network device after the handover is completed when the terminal device is handed over from a first access network device supporting a multicast / broadcast transmission mode to a second access network device not supporting a multicast / broadcast transmission mode.

[0303] In this scenario, the MBS is transmitted between the second access network device and the terminal device in unicast mode. In this case, if the terminal device performs a cell handover again and is handed over from the second access network device to a third access network device supporting the multicast-broadcast transmission mode, after the handover is performed according to the existing handover procedure, the MBS is still transmitted between the third access network device and the terminal device in unicast mode.

[0304] This may cause the waste of transmission resources between the third access network device and the terminal device. For example, the third access network device transmits MBS to another terminal in a multicast mode. If the third access network device still transmits MBS to the terminal device in a unicast mode, the third access network device repeatedly sends MBS, resulting in the waste of transmission resources of the third access network.

[0305] Therefore, one embodiment of the present application further provides the following method to solve the waste of transmission resources caused by repeated transmission of MBS when a terminal device is handed over from an access network device that does not support a multicast broadcast transmission mode to an access network device that supports a multicast broadcast transmission mode.

[0306] As shown in FIG. 11, the method includes the following steps.

[0307] S1100: A core network device determines whether a transmission progress of an MBS transmitted in unicast mode is greater than or equal to a transmission progress of an MBS transmitted in multicast mode.

[0308] Specifically, before the handover, the MBS is transmitted in unicast mode between the access network device that does not support the multicast / broadcast transmission mode and the terminal device, and after the handover, the MBS is still transmitted in unicast mode between the terminal device and the third access network device.

[0309] In this case, the core network device determines whether the third access network device supports a multicast / broadcast transmission mode.

[0310] If yes, the core network device determines whether the third access network device is currently transmitting the MBS in multicast mode.

[0311] If yes, the core network device determines the progress of the transmission of the MBSs transmitted in unicast mode and the progress of the transmission of the MBSs transmitted in multicast mode.

[0312] The core network device determines whether the transmission progress of the MBS transmitted in unicast mode is greater than or equal to the transmission progress of the MBS transmitted in multicast mode.

[0313] S1101: If yes, the core network device sends sixth indication information to the third access network device. In response, the third access network device receives sixth indication information from the core network device.

[0314] The sixth indication information instructs the third access network device to configure the unicast session as a multicast session.

[0315] In one example, the sixth indication information is session modification information.

[0316] In a possible implementation, the core network device determines an identifier of a data packet of the MBS currently being transmitted in unicast mode and an identifier of a data packet of the MBS currently being transmitted in multicast mode. If the identifier of the data packet of the MBS currently being transmitted in unicast mode is equal to or greater than the identifier of the data packet of the MBS currently being transmitted in multicast mode, For example, if the core network device determines that the identifier of a data packet of an MBS currently transmitted in unicast mode is data packet #9 and the identifier of a data packet of an MBS currently transmitted in unicast mode is data packet #7, the progress of the transmission of the MBS transmitted in unicast mode is greater than the progress of the transmission of the MBS transmitted in multicast mode, and the core network device sends a sixth indication information to the third access network device.

[0317] If the core network device determines that the identifier of a data packet of an MBS currently being transmitted in unicast mode is data packet #9 and the identifier of a data packet of an MBS currently being transmitted in unicast mode is data packet #11, the progress of transmission of the MBS transmitted in unicast mode is less than the progress of transmission of the MBS transmitted in multicast mode.

[0318] At this time, when the core network device sends the sixth indication information to the third access network device, the third access network device may directly associate the MBS transmitted in unicast mode with the MBS transmitted in multicast mode. The data packet #10 of the MBS transmitted in unicast mode by the third access network device is not sent, but the data packet #10 of the MBS transmitted in multicast mode by the third access network device is sent. In this case, if the MBS is directly associated with the MBS transmitted in multicast mode, the terminal device cannot receive the data packet #10.

[0319] Therefore, in this case, the core network device does not send the sixth indication information to the third access network device. The core network device may suspend the MBS transmitted in the multicast mode until the progress of the transmission of the MBS transmitted in the unicast mode is equal to or greater than the progress of the transmission of the MBS transmitted in the multicast mode.

[0320] S1102: The third access network device sends fourth indication information to the terminal device. In response, the terminal device receives the fourth indication information from the third access network device.

[0321] The fourth indication information instructs the terminal device to configure the second radio bearer as the first radio bearer, where the first radio bearer is a multicast radio bearer and the second radio bearer is a unicast radio bearer.

[0322] S1103: The terminal device delivers a data packet in a PDCP entity corresponding to the first radio bearer to an upper layer protocol entity.

[0323] The upper layer protocol entity is the protocol layer at which the data transmitted by the PDCP entity is received, for example, the transmission control protocol / internet protocol (TCP / IP) layer, the application layer, or the user datagram protocol (UDP) layer, which is not limited in this application.

[0324] In a possible implementation, the terminal device delivers all data packets received at the PDCP entity corresponding to the first radio bearer to a higher layer protocol entity.

[0325] In another possible implementation, the terminal device delivers data packets received consecutively in the PDCP entity corresponding to the first radio bearer to the upper layer protocol entity in sequence. The terminal device deletes other data packets, for example, data packets after a receiving hole. The hole is the serial number corresponding to the data packet that is not received. For example, if the PDCP entity includes data packet #1, data packet #2, and data packet #4, the serial number corresponding to data packet #3 is indicated as the data packet of the hole.

[0326] In one example, if the PDCP entity corresponding to the first radio bearer of the terminal device includes data packet #1, data packet #2, and data packet #4, the terminal device delivers data packet #1 and data packet #2 to the upper layer protocol entity, and the terminal device deletes data packet #4. Data packet #3 corresponds to a reception hole.

[0327] S1104: The terminal device performs at least one of the following operations to configure the second radio bearer as the first radio bearer. Establish a PTM RLC entity, configure an MBS identifier, and delete the security configuration in the second radio bearer configuration.

[0328] Specifically, the process in which the terminal device configures the second radio bearer as the first radio bearer is opposite to the process in which the terminal device configures the first radio bearer as the second radio bearer. For specific implementation, please refer to the aforementioned process of configuring the first radio bearer as the second radio bearer shown in Figure 8. Details will not be described again here.

[0329] It should be noted that in the process of configuring the second radio bearer as the first radio bearer, after the second radio bearer is configured as the first radio bearer, the third access network device performs MBS transmission based on the case in which the MBS is transmitted via the first radio bearer. Therefore, the transmission status and the transmission parameters of the transmission window of the PDCP entity of the second radio bearer need to be reconfigured based on the transmission status, and the transmission parameters of the transmission window of the PDCP entity of the first radio bearer for transmitting the MBS need to be configured.

[0330] S1105: The terminal device sends the fifth indication information to the third access network device. In response, the third access network device sends the fifth indication information to the terminal device.

[0331] The fifth indication information indicates a serial number corresponding to a data packet that is not successfully received by the terminal device.

[0332] Specifically, when the terminal device delivers all data packets in the PDCP entity corresponding to the first radio bearer to the upper layer protocol entity, the fifth indication information indicates all data packets that are not received by the terminal device.

[0333] The terminal device sequentially delivers successively received data packets in a PDCP entity corresponding to a first radio bearer to an upper layer protocol entity, and when the terminal device deletes another data packet, for example, a data packet after a reception hole, the terminal device reports the serial number corresponding to the reception hole or the serial number of the first data packet after the reception hole to instruct the third access network device to perform transmission from the data packet.

[0334] For example, in relation to the example of S1103, the terminal device reports the serial number of data packet #3. After receiving the serial number of data packet #3, the third access network device starts transmitting from data packet #3.

[0335] It should be noted that the fifth indication information may indicate the serial number of the data packet in the form of a bitmap, or may directly indicate the serial number of the data packet, which is not limited in this application.

[0336] S1106: The third access network device sends the MBD service to the terminal device through the first radio bearer. Correspondingly, the terminal device receives the MBD service from the third access network device through the first radio bearer.

[0337] It should be noted that in this application, an example in which a terminal device is handed over from a second access network device to a third access network device is used for explanation. In actual processing, this method is applicable to a scenario in which a terminal device is handed over to an access network device that supports a multicast / broadcast transmission mode when an MBS is transmitted between the terminal device and the access network device in a unicast mode. This is not limited in this application.

[0338] According to the above technical solution, an embodiment of the present application provides a communication method: when a terminal device is handed over from an access network device that does not support a multicast / broadcast transmission mode to an access network device that supports a multicast / broadcast transmission mode, if an MBS is transmitted between the terminal device and the access network device in a unicast mode, the MBS is mapped to an MBS transmitted in a multicast mode, which solves the waste of transmission resources caused by repeated transmission of the MBS.

[0339] The foregoing mainly describes the solutions in the embodiments of the present application from the perspective of interactions between network elements. To implement the aforementioned functions, it can be understood that the network elements, for example, the terminal device, the access network device (e.g., the first access network device, the second access network device, and / or the third access network device), and the core network device, include at least one of corresponding hardware structures and software modules for performing each function. Those skilled in the art should easily realize that the present application can be implemented by hardware or a combination of hardware and computer software in combination with the example units and algorithm steps described in the embodiments disclosed herein. Whether the functions are performed by hardware or by hardware driven by computer software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the functions described for each specific application, but this implementation should not be considered to go beyond the scope of the present application.

[0340] In the embodiment of the present application, the access network device, the core network device, and the terminal device may be divided into functional units based on the example of the method. For example, each functional unit may be obtained by division based on the corresponding function, or two or more functions may be integrated into one processing unit. The integrated unit may be implemented in the form of hardware or in the form of a software functional unit. It should be noted that in the embodiment of the present application, the division into units is an example and is only a logical functional division. There may be another division scheme during actual implementation.

[0341] When an integrated unit is used, Figure 12 is a schematic diagram of a possible structure of a communication device (shown as communication device 120) in the aforementioned embodiment. The communication device 120 includes a processing unit 1201 and a communication unit 1202, and may further include a storage unit 1203. The schematic diagram of the structure shown in Figure 12 can be used to illustrate the structure of an access network device, a core network device, or a terminal device in the aforementioned embodiment.

[0342] When the schematic diagram of the structure shown in FIG. 12 is used to illustrate the structure of the terminal device in the aforementioned embodiment, the processing unit 1201 is configured to control and manage the operation of the terminal device, for example, to control the terminal device to perform S600 and S601 of FIG. 6, S600, S601, S700, S701, and S704 of FIG. 7, S903 of FIG. 9, S1000, S1001, S1006, and S903 of FIG. 10, S1102 to S1106 of FIG. 11, and / or to control and manage the operation performed by the terminal device in another process described in the embodiment of the present application. The processing unit 1201 may communicate with another network entity via the communication unit 1202, for example, with the first access network device and the second access network device shown in FIG. 2. The storage unit 1203 is configured to store program codes and data of the terminal device.

[0343] When the structural schematic diagram shown in FIG. 12 is used to illustrate the structure of the terminal device in the above embodiment, the communication device 120 may be the terminal device or a chip in the terminal device.

[0344] When the schematic diagram of the structure shown in Figure 12 is used to illustrate the structure of the first access network device in the aforementioned embodiment, the processing unit 1201 is configured to control and manage the operation of the first access network device, for example, to control the first access network device to perform S600 and S601 in Figure 6, S600, S601, and S700-S703 in Figure 7, S900, S901, and S902 in Figure 9, S900, S902, S1000-S1003, and S1005-S1007 in Figure 10, and / or to control and manage the operation performed by the first access network device in another process described in the embodiment of the present application. The processing unit 1201 may communicate with another network entity via the communication unit 1202, for example, with the terminal device and the access network device shown in Figure 2. The memory unit 1203 is configured to store program codes and data for the first access network device.

[0345] When the schematic structure diagram shown in FIG. 12 is used to illustrate the structure of the first access network device in the above embodiment, the communication device 120 may be the first access network device or may be a chip in the first access network device.

[0346] When the schematic diagram of the structure shown in FIG. 12 is used to illustrate the structure of the second access network device in the aforementioned embodiment, the processing unit 1201 is configured to control and manage the operation of the second access network device, for example, to control the second access network device to perform S902 and S903 of FIG. 9, S902, S903, S1003-S1005, S1008, and S1009 of FIG. 10, and / or to control and manage the operation performed by the second access network device in another process described in the embodiment of the present application. The processing unit 1201 may communicate with another network entity via the communication unit 1202, for example, with the terminal device and the first access network device shown in FIG. 2. The storage unit 1203 is configured to store program codes and data of the second access network device.

[0347] When the schematic structure diagram shown in FIG. 12 is used to illustrate the structure of the second access network device in the above embodiment, the communication device 120 may be the second access network device or may be a chip in the second access network device.

[0348] When the schematic diagram of the structure shown in FIG. 12 is used to illustrate the structure of the third access network device in the aforementioned embodiment, the processing unit 1201 is configured to control and manage the operation of the third access network device, for example, to control the third access network device to execute S1101, S1102, S1105, and S1106 of FIG. 11, and / or to control and manage the operation performed by the third access network device in another process described in the embodiment of the present application. The processing unit 1201 may communicate with another network entity via the communication unit 1202, for example, with the terminal device and the first access network device shown in FIG. 2. The storage unit 1203 is configured to store program codes and data of the third access network device.

[0349] When the schematic structure diagram shown in FIG. 12 is used to illustrate the structure of the third access network device in the above embodiment, the communication device 120 may be the third access network device or may be a chip in the third access network device.

[0350] When the schematic diagram of the structure shown in FIG. 12 is used to illustrate the structure of the core network device in the aforementioned embodiment, the processing unit 1201 is configured to control and manage the operation of the core network device, for example, to control the core network device to perform S704 of FIG. 7, S900 of FIG. 9, S900, S1008, and S1009 of FIG. 10, S1100, and S1101 of FIG. 11, and / or to control and manage the operation performed by the terminal device in another process described in the embodiment of the present application. The processing unit 1201 may communicate with another network entity via the communication unit 1202, for example, with the terminal device and the first core network device shown in FIG. 2. The storage unit 1203 is configured to store program codes and data of the core network device.

[0351] When the schematic structure diagram shown in Figure 12 is used to illustrate the structure of the core network device in the above embodiment, the communication device 120 may be the core network device or may be a chip within the core network device.

[0352] When the communication device 120 is a terminal device, an access network device, or a core network device, the processing unit 1201 may be a processor or a controller, and the communication unit 1202 may be a communication interface, a transceiver, a transceiver circuit, a transceiver device, etc. The communication interface is a general term and may include one or more interfaces. The storage unit 1203 may be a memory. When the communication device 120 is a chip in a terminal device, an access network device, or a core network device, the processing unit 1201 may be a processor or a controller, and the communication unit 1202 may be an input interface and / or an output interface, a pin, a circuit, etc. The storage unit 1203 may be a storage unit (e.g., a register or a cache) in the chip, or a storage unit (e.g., a read-only memory (ROM for short), or a random access memory (RAM for short)) off the chip and in the terminal device, the access network device, or the core network device.

[0353] The communication unit may also be referred to as a transceiver unit. The antenna and the control circuit having the transceiver function in the communication device 120 may be considered as the communication unit 1202 of the communication device 120, and the processor having the processing function may be considered as the processing unit 1201 of the communication device 120. Optionally, a component configured to implement the receiving function in the communication unit 1202 may be considered as a receiving unit. The receiving unit is configured to perform the receiving step in the embodiment of the present application. The receiving unit may be a receiver, a receiving circuit, etc.

[0354] When implemented in the form of a software functional module and sold or used as an independent product, the integrated unit in FIG. 12 may be stored in a computer-readable storage medium. Based on such understanding, the technical solutions of the embodiments of the present application essentially, or the part that contributes to the prior art, or all or part of the technical solutions may be implemented in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for instructing a computer device or a processor (which may be a personal computer, a server, a network device, etc.) to execute all or some of the steps of the method described in the embodiments of the present application. The storage medium for storing the computer software product includes any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory, a random access memory, a magnetic disk, or an optical disk.

[0355] The units in Figure 12 may alternatively be referred to as modules, for example a processing unit may be referred to as a processing module.

[0356] An embodiment of the present application further provides a schematic diagram of a hardware structure of a communication device (denoted as communication device 130). See Fig. 13 or Fig. 14. The communication device 130 includes a processor 1301, and optionally further includes a memory 1302 connected to the processor 1301.

[0357] Refer to FIG. 13. In a first possible implementation, the communication device 130 further includes a transceiver 1303. The processor 1301, the memory 1302, and the transceiver 1303 are connected via a bus. The transceiver 1303 is configured to communicate with another device or a communication network. Optionally, the transceiver 1303 may include a transmitter and a receiver. A component configured to implement a receiving function in the transceiver 1303 may be regarded as a receiver. The receiver is configured to perform a receiving step in the embodiment of the present application. A component configured to implement a sending function in the transceiver 1303 may be regarded as a transmitter. The transmitter is configured to perform a sending step in the embodiment of the present application.

[0358] Based on the first possible implementation, the schematic diagram of the structure shown in FIG. 13 may be used to illustrate the structure of the terminal device, the first access network device, the second access network device, the third access network device, or the core network device in the aforementioned embodiments.

[0359] When the schematic diagram of the structure shown in FIG. 13 is used to illustrate the structure of the terminal device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the terminal device. For example, the processor 1301 is configured to support the terminal device in performing S600 and S601 of FIG. 6, S600, S601, S700, S701, and S704 of FIG. 7, S903 of FIG. 9, S1000, S1001, S1006, and S903 of FIG. 10, S1102-S1106 of FIG. 11, and / or operations performed by the terminal device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity via the transceiver 1303, for example, with the first access network device and the second access network device shown in FIG. 2. The memory 1302 is configured to store program codes and data of the terminal device.

[0360] When the schematic diagram of the structure shown in FIG. 13 is used to illustrate the structure of the first access network device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the terminal device. For example, the processor 1301 is configured to support the first access network device in executing S600 and S601 of FIG. 6, S600, S601, and S700-S703 of FIG. 7, S900, S901, and S902 of FIG. 9, S900, S902, S1000-S1003, and S1005-S1007 of FIG. 10, and / or the operation performed by the first access network device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity via the transceiver 1303, for example, with the terminal device and the access network device shown in FIG. 2. The memory 1302 is configured to store program codes and data of the first access network device.

[0361] When the schematic diagram of the structure shown in FIG. 13 is used to illustrate the structure of the second access network device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the second access network device. For example, the processor 1301 is configured to support the second access network device in performing S902 and S903 of FIG. 9, S902, S903, S1003-S1005, S1008, and S1009 of FIG. 10, and / or the operations performed by the second access network device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity via the transceiver 1303, for example, with the terminal device and the core network device shown in FIG. 2. The memory 1302 is configured to store program codes and data of the second access network device.

[0362] When the schematic diagram of the structure shown in FIG. 13 is used to illustrate the structure of the third access network device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the third access network device. For example, the processor 1301 is configured to support the third access network device in performing S1101, S1102, S1105, and S1106 of FIG. 11, and / or the operation performed by the third access network device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity via the transceiver 1303, for example, with the terminal device and the core network device shown in FIG. 2. The memory 1302 is configured to store program codes and data of the third access network device.

[0363] When the schematic diagram of the structure shown in Figure 13 is used to illustrate the structure of the core network device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the access network device. For example, the processor 1301 is configured to support the access network device in performing S704 of Figure 7, S900 of Figure 9, S900, S1008, and S1009 of Figure 10, S1100 and S1101 of Figure 11, and / or the operation performed by the access network device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity via the transceiver 1303, for example, with the terminal device and the core network device shown in Figure 1. The memory 1302 is configured to store program codes and data of the access network device.

[0364] In a second possible implementation, the processor 1301 includes a logic circuit and at least one of an input interface and an output interface, the output interface being configured to perform a sending operation in a corresponding manner, and the input interface being configured to perform a receiving operation in a corresponding manner.

[0365] Refer to Figure 14. Based on a second possible implementation, the schematic diagram of the structure shown in Figure 14 can be used to illustrate the structure of a terminal device, an access network device, or a core network device in the above embodiment.

[0366] When the schematic diagram of the structure shown in FIG. 14 is used to illustrate the structure of the terminal device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the terminal device. For example, the processor 1301 is configured to support the terminal device in executing S600 and S601 of FIG. 6, S600, S601, S700, S701, and S704 of FIG. 7, S903 of FIG. 9, S1000, S1001, S1006, and S903 of FIG. 10, S1102-S1106 of FIG. 11, and / or operations performed by the terminal device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity via at least one of the input interface and the output interface, for example, with the first access network device and the second access network device shown in FIG. 2. The memory 1302 is configured to store program codes and data of the terminal device.

[0367] When the schematic diagram of the structure shown in FIG. 14 is used to illustrate the structure of the first access network device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the first access network device. For example, the processor 1301 is configured to support the first access network device in performing S600 and S601 in FIG. 6, S600, S601, and S700-S703 in FIG. 7, S900, S901, and S902 in FIG. 9, S900, S902, S1000-S1003, and S1005-S1007 in FIG. 10, and / or the operations performed by the first access network device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity via at least one of the input interface and the output interface, for example, with the terminal device and the access network device shown in FIG. 1. The memory 1302 is configured to store program codes and data for the first access network device.

[0368] When the schematic diagram of the structure shown in FIG. 14 is used to illustrate the structure of the second access network device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the second access network device. For example, the processor 1301 is configured to support the second access network device in performing S902 and S903 of FIG. 9, S902, S903, S1003-S1005, S1008, and S1009 of FIG. 10, and / or the operations performed by the second access network device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity via at least one of the input interface and the output interface, for example, with the terminal device and the first access network device shown in FIG. 2. The memory 1302 is configured to store program codes and data of the second access network device.

[0369] When the schematic diagram of the structure shown in FIG. 14 is used to illustrate the structure of the third access network device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the third access network device. For example, the processor 1301 is configured to support the third access network device in performing S1101, S1102, S1105, and S1106 of FIG. 11, and / or the operation performed by the third access network device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity through at least one of the input interface and the output interface, for example, with the terminal device and the first access network device shown in FIG. 2. The memory 1302 is configured to store program codes and data of the third access network device.

[0370] When the schematic diagram of the structure shown in Figure 14 is used to illustrate the structure of the core network device in the aforementioned embodiment, the processor 1301 is configured to control and manage the operation of the core network device. For example, the processor 1301 is configured to support the core network device in performing S704 of Figure 7, S900 of Figure 9, S900, S1008, and S1009 of Figure 10, S1100 and S1101 of Figure 11, and / or the operations performed by the core network device in another process described in the embodiment of the present application. The processor 1301 may communicate with another network entity through at least one of the input interface and the output interface, for example, with the terminal device and the first core network device shown in Figure 2. The memory 1302 is configured to store the program code and data of the core network device.

[0371] 13 and 14 may alternatively show a system chip in an access network device, respectively. In this case, the operations performed by the access network device may be implemented by the system chip. For the specific operations performed, please refer to the above description. Details will not be described again in this specification. 13 and 14 may alternatively show a system chip in a terminal device, respectively. In this case, the operations performed by the terminal device may be implemented by the system chip. For the specific operations performed, please refer to the above description. Details will not be described again in this specification. 13 and 14 may alternatively show a system chip in an access network device, respectively. In this case, the operations performed by the first access network device may be implemented by the system chip. For the specific operations performed, please refer to the above description. Details will not be described again in this specification.

[0372] In addition, the embodiment of the present application further provides a schematic diagram of the hardware structure of a terminal device (depicted as terminal device 150) and an access network device (depicted as access network device 160). For details, please refer to Figure 15 and Figure 14, respectively. The terminal device 150 may be a terminal device or a first access network device.

[0373] Fig. 15 is a schematic diagram of the hardware configuration of the terminal device 150. For ease of explanation, Fig. 15 shows only the main components of the terminal device. As shown in Fig. 15, the terminal device 150 includes a processor, a memory, a control circuit, an antenna, and an input / output device.

[0374] The processor is primarily configured to process communication protocols and communication data, control the entire terminal device, execute software programs, process data of the software programs, and control the terminal device to execute, for example, S600 and S601 of FIG. 6, S600, S601, S700, S701, and S704 of FIG. 7, S903 of FIG. 9, S1000, S1001, S1006, and S903 of FIG. 10, and S1102 to S1106 of FIG. 11.

[0375] The memory is primarily configured to store software programs and data. The control circuit (which may also be called radio frequency circuitry) is primarily configured to perform conversion between baseband signals and radio frequency signals and process radio frequency signals. The control circuitry and antenna together may be called a transceiver and are primarily configured to transmit and receive radio frequency signals in the form of electromagnetic waves. The input / output device, e.g., a touch screen, a display, or a keyboard, is primarily configured to receive data entered by a user and output data to the user.

[0376] After the terminal device is powered on, the processor can read the software program in the memory, interpret and execute the instructions of the software program, and process the data of the software program. When the processor needs to send data through the antenna, after performing baseband processing on the data to be transmitted, the processor transmits the baseband signal to the control circuit. On the road The control circuit performs radio frequency processing on the baseband signal, and then sends the radio frequency signal to the outside in the form of electromagnetic waves through an antenna. When data is sent to the terminal device, the control circuit receives the radio frequency signal through the antenna, converts the radio frequency signal to a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal to data and processes the data.

[0377] Those skilled in the art may understand that for simplicity of explanation, FIG. 15 shows only one memory and one processor. In an actual terminal device, there may be multiple processors and memories. The memory may also be referred to as a storage medium, a storage device, etc. This is not limited in the embodiment of the present application.

[0378] In an optional implementation, the processor may include a baseband processor and a central processing unit. The baseband processor is mainly configured to process communication protocols and communication data. The central processing unit is mainly configured to control the entire terminal device, execute software programs, and process data of the software programs. The functions of the baseband processor and the central processing unit are integrated into the processor of FIG. 15. Those skilled in the art may understand that the baseband processor and the central processing unit may alternatively be independent processors and are interconnected by using a technique, for example, a bus. Those skilled in the art may understand that the terminal device may include multiple baseband processors to be adapted to different network standards, the terminal device may include multiple central processing units to enhance the processing capabilities of the terminal device, and the components of the terminal device may be connected via various buses. Alternatively, the baseband processor may be expressed as a baseband processing circuit or a baseband processing chip. Alternatively, the central processing unit may be expressed as a central processing circuit or a central processing chip. The function of processing the communication protocol and the communication data may be built into the processor or may be stored in the memory in the form of a software program. The processor executes the software program to implement the baseband processing function.

[0379] 16 is a schematic diagram of a hardware structure of an access network device 160. The access network device 160 may include one or more radio frequency units, such as a remote radio unit (RRU) 1601, and one or more baseband units (BBUs) 1602 (which may also be referred to as digital units (DUs)).

[0380] The RRU 1601 may also be referred to as a transceiver unit, a transceiver, a transceiver circuit, etc., and may include at least one antenna 1611 and a radio frequency unit 1612. The RRU 1601 is mainly configured to transmit and receive radio frequency signals, and perform conversion between radio frequency signals and baseband signals. The RRU 1601 and the BBU 1602 may be physically co-located or physically separated, for example, in distributed base stations.

[0381] The BBU 1602 is the control center of the access network device, also called a processing unit, and is mainly configured to complete baseband processing functions, such as channel coding, multiplexing, modulation, or spectrum spreading.

[0382] In one embodiment, the BBU 1602 may include one or more boards. The multiple boards may jointly support a radio access network of a single access standard (e.g., an LTE network) or may separately support radio access networks of different access standards (such as an LTE network, a 5G network, or another network). The BBU 1602 further includes a memory 1621 and a processor 1622. The memory 1621 is configured to store necessary instructions and data. The processor 1622 is configured to control the access network device to perform necessary operations. The memory 1621 and the processor 1622 may serve one or more boards. In other words, the memory and the processor may be independently disposed on each board. Alternatively, the multiple boards may share the same memory and the same processor. In addition, necessary circuits may be further disposed on each board.

[0383] It should be understood that the access network device 160 shown in Figure 16 can perform S600 and S601 of Figure 6, S600, S601, and S700-S703 of Figure 7, S900, S901, and S902 of Figure 9, S900, S902, S1000-S1003, and S1005-S1007 of Figure 10, or S902 and S903 of Figure 9, S902, S903, S1003-S1005, S1008, and S1009 of Figure 10, or S1101, S1102, S1105, and S1106 of Figure 11, and / or operations performed by the access network device in another process described in the embodiments of the present application. The operation or function or operation and function of each module in the access network device 160 is set separately to implement the corresponding procedure in the embodiment of the method described above. For details, please refer to the description in the above method embodiment. In order to avoid repetition, detailed descriptions are appropriately omitted in this specification.

[0384] In the implementation process, the steps in the method provided in the embodiment can be completed by using logic circuits integrated in hardware in a processor, or by using instructions in the form of software. The steps in the method disclosed in relation to the embodiments of the present application may be directly executed by a hardware processor, or may be executed by using a combination of hardware and software modules in a processor.

[0385] The processor in this application may include, but is not limited to, at least one of the following computing devices that execute software: a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a microcontroller unit (MCU), an artificial intelligence processor, etc. Each computing device may include one or more cores configured to perform an operation or process by executing software instructions. The processor may be an independent semiconductor chip or may be integrated with another circuit in a semiconductor chip. For example, the processor may form a system-on-a-chip (SoC) with another circuit (e.g., a codec circuit, a hardware acceleration circuit, or various bus and interface circuits). Alternatively, the processor may be integrated in an ASIC as an embedded processor of the ASIC, and the ASIC integrated with the processor may be packaged separately or with another circuit. In addition to the cores configured to perform operations or processing by executing software instructions, the processor may further include necessary hardware accelerators, such as a field programmable gate array (FPGA), a programmable logic device (PLD), or logic circuitry that implements dedicated logical operations.

[0386] The memory in the embodiment of the present application may include at least one of the following types: read-only memory (ROM) or another type of static storage device capable of storing static information and instructions, random access memory (RAM) or another type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM). In some scenarios, the memory may alternatively be a compact disc read-only memory (CD-ROM) or another compact disc storage, an optical disc storage (including a compact disc, a laser disc, an optical disc, a digital versatile disc, a Blu-ray disc, etc.), a magnetic disc storage medium or another magnetic storage device, or any other medium that can be configured to carry or store expected program code in the form of instructions or data structures and that can be accessed by a computer. However, the memory is not limited thereto.

[0387] An embodiment of the present application further provides a computer-readable storage medium comprising instructions, which when executed on a computer, enable the computer to perform any one of the methods described above.

[0388] An embodiment of the present application further provides a computer program product comprising instructions, which when executed on a computer, enables the computer to perform any one of the methods described above.

[0389] An embodiment of the present application further provides a communication system, including the aforementioned terminal device, a first access network device, a second access network device, a core network device, and / or a third access network device.

[0390] An embodiment of the present application further provides a chip, the chip including a processor and an interface circuit, the interface circuit being coupled to the processor, the processor being configured to execute a computer program or instructions to implement the aforementioned method, the interface circuit being configured to communicate with another module outside the chip.

[0391] All or part of the above-mentioned embodiments may be implemented by using software, hardware, firmware, or any combination thereof. When a software program is used to implement the embodiments, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the procedures or functions according to the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or another programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center in a wired (e.g., coaxial cable, optical fiber, or digital subscriber line (DSL)) or wireless (e.g., infrared, radio, or microwave) manner. A computer-readable storage medium may be any available medium accessible by a computer, or a data storage device that integrates one or more available media, such as a server or a data center. The available media may be magnetic media (e.g., floppy disks, hard disks, or magnetic tapes), optical media (e.g., DVDs), semiconductor media (e.g., solid state disks (SSDs)), etc.

Claims

1. receiving, by the first access network device, third indication information, the third indication information indicating a correspondence relationship between a unicast quality of service flow and a Multicast and Broadcast Service (MBS) Quality of Service (QoS) flow; replacing, by the first access network device, a flow identifier in a data packet header of the MBS quality of service flow with the flow identifier of the unicast quality of service flow associated with the MBS quality of service flow during a handover process; forwarding, by the first access network device, the unicast quality of service flow after replacing the flow identifier to a second access network device, the second access network device being an access network device that does not support a multicast / broadcast transmission mode; A communication method including:

2. The method of claim 1 , wherein the third indication information includes a flow identifier of the unicast quality of service flow corresponding to the MBS quality of service flow.

3. Before the handover process, the first access network device transmits an MBS to the terminal device in a multicast transmission mode; The method according to claim 1 or 2.

4. The method according to claim 1 , wherein the handover process is a process in which a terminal device hands over from the first access network device to the second access network device supporting a multicast / broadcast transmission mode.

5. Prior to forwarding the unicast quality of service flow by the first access network device to a second access network device, the method further comprises: sending a handover request to the second access network device, the handover request including information of a multicast and broadcast service; receiving a handover request acknowledgement information from the second access network device, the handover request acknowledgement information including first configuration information, the first configuration information including information for a cell handover, and if information of the multicast / broadcast service is information that cannot be identified by the second access network device, the first configuration information is a complete configuration; The method of claim 1 , further comprising:

6. 6. The method according to claim 1, further comprising the step of the first access network device determining that the second access network device does not support the multicast / broadcast transmission mode by performing a signaling interaction with the second access network device.

7. The method comprises: sending, by a first access network device, first indication information to a terminal device, the first indication information instructing the terminal device to set a first radio bearer as a second radio bearer, the first radio bearer being a multicast radio bearer and the second radio bearer being a unicast radio bearer; sending, by the first access network device, an MBS to the terminal device via the second radio bearer; The method of claim 1 , further comprising:

8. 8. The method of claim 7, wherein the first indication information indicates in particular at least one of the following information of the second radio bearer: Packet Data Convergence Protocol (PDCP) configuration information, Radio Link Control (RLC) configuration information, security configuration information, and an identifier of the second radio bearer.

9. The method comprises: The method according to claim 7 or 8, further comprising the step of sending the first indication information to the terminal device before the handover process.

10. A communication device comprising a communication unit and a processing unit, The processing unit is configured to instruct the communication unit to receive third indication information, the third indication information indicating a correspondence relationship between a unicast quality of service flow and a Multicast and Broadcast Service (MBS) Quality of Service (QoS) flow; The processing unit is further configured to replace a flow identifier in a data packet header of the MBS quality of service flow with the flow identifier of the unicast quality of service flow associated with the MBS quality of service flow in a handover process; The processing unit is further configured to instruct the communication unit to forward the unicast quality of service flow after replacing the flow identifier to a second access network device, the second access network device being an access network device that does not support a multicast / broadcast transmission mode.

11. The apparatus of claim 10 , wherein the third indication information includes a flow identifier of the unicast quality of service flow that corresponds to the MBS quality of service flow.

12. Before the handover process, the device transmits an MBS to the terminal device in a multicast transmission mode; 12. Apparatus according to claim 10 or 11.

13. The apparatus according to claim 10 , wherein the handover process is a process in which a terminal device hands over from the communication apparatus supporting the multicast / broadcast transmission mode to the second access network device.

14. The communication unit is further configured to send a handover request to a second access network device, the handover request including information of the multicast and broadcast service; The apparatus of any one of claims 10 to 13, wherein the communication unit is further configured to receive acknowledgement information of a handover request from the second access network device, the acknowledgement information of the handover request including first configuration information, the first configuration information including information for a cell handover, and if information of the multicast / broadcast service is information that cannot be identified by the second access network device, the first configuration information is a complete configuration.

15. 11. The apparatus of claim 10, wherein the processing unit is further configured to determine that the second access network device does not support the multicast / broadcast transmission mode by performing signaling interaction with the second access network device.

16. The communication unit sends first indication information to a terminal device, the first indication information instructing the terminal device to set a first radio bearer as a second radio bearer, the first radio bearer being a multicast radio bearer and the second radio bearer being a unicast radio bearer; Sending MBS to the terminal device via the second radio bearer.

16. The apparatus of claim 10, further configured to:

17. 17. The apparatus of claim 16, wherein the first indication information indicates, in particular, at least one of the following information of the second radio bearer: Packet Data Convergence Protocol (PDCP) configuration information, Radio Link Control (RLC) configuration information, security configuration information, and an identifier of the second radio bearer.

18. The apparatus according to claim 16 or 17, wherein the communication unit is further configured to send the first indication information to the terminal device before the handover procedure.

19. A method for providing a handover to a second access network device, comprising: receiving, by the second access network device, a handover request from the first access network device; sending, by the second access network device, an acknowledgement information of the handover request to the first access network device, the second access network device being an access network device that does not support a multicast / broadcast transmission mode; receiving a unicast quality of service (QoS) flow from a first access network device, the unicast quality of service flow being obtained by replacing a flow identifier in a data packet header of a Multicast and Broadcast Service (MBS) QoS flow with the flow identifier of a corresponding unicast quality of service flow; A communication method comprising:

20. The method of claim 19, wherein the handover request acknowledgement information includes first configuration information.

21. The method according to claim 20, wherein the handover request includes information about a multicast / broadcast service, the method further comprising: generating, by the second access network device, first configuration information, the first configuration information including information for cell handover, and if the information of the multicast / broadcast service is information that cannot be identified by the second access network device, the first configuration information is a complete configuration; 21. The method of claim 20, further comprising:

22. The method according to claim 21, indicating whether the second access network device supports the multicast / broadcast transmission mode by performing a signaling interaction with the first access network device.

22. The method of any one of claims 19 to 21, further comprising:

23. A communication device comprising a communication unit and a processing unit, The processing unit includes: receiving a handover request from a first access network device; sending a handover request acknowledgement information to the first access network device, the communication device being an access network device that does not support multicast and broadcast transmission modes; receiving a unicast quality of service (QoS) flow from a first access network device, the unicast quality of service flow being obtained by replacing a flow identifier in a data packet header of a Multicast and Broadcast Service (MBS) QoS flow with the flow identifier of a corresponding unicast quality of service flow; 23. A communication device configured to:

24. The apparatus of claim 23, wherein the handover request acknowledgement information includes first configuration information.

25. The handover request includes information about a multicast / broadcast service, and the processing unit: generating first configuration information, the first configuration information including information for cell handover, and if the information of the multicast / broadcast service is information that cannot be identified by the communication device, the first configuration information being a complete configuration; 25. The apparatus of claim 24, further configured to perform:

26. The processing unit, indicating whether the communication device supports the multicast / broadcast transmission mode by performing a signaling interaction with the first access network device; 26. The apparatus of claim 23, further configured to:

27. A communications device, the device comprising a processor, the processor configured to execute programs or instructions stored in a memory, thereby implementing a method according to any one of claims 1 to 9.

28. 10. A computer readable storage medium storing instructions that, when executed on a computer, enable the computer to perform the method of any one of claims 1 to 9.

29. A computer program comprising instructions which, when executed by a computer, implement the method of any one of claims 1 to 9.

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