Wireless communication method, terminal device, and access network device

Abstract

Provided are a wireless communication method, a terminal device, and an access network device. The method comprises: a terminal device performs a handover operation, the handover operation comprising handing over between a first access network device and a second access network device, wherein a radio access technology (RAT) corresponding to the first access network device is different from a RAT corresponding to the second access network device. In embodiments of the present application, the terminal device can hand over between the first access network device and the second access network device, wherein the RAT corresponding to the first access network device is different from the RAT corresponding to the second access network device, which helps to avoid interruption of the connection between the terminal device and a network.

Description

Method, terminal device and access network device for wireless communication TECHNICAL FIELD

[0001] The present application relates to the technical field of communication, and more particularly, to a method, a terminal device and an access network device for wireless communication. BACKGROUND

[0002] When a new generation technology appears, the deployment of a new radio access technology (RAT) needs to be gradually expanded in business, so the coverage of the network of the new RAT is initially limited. At this time, if the terminal device moves, it may move out of the coverage of the new RAT, at which time the terminal device loses contact with the network. SUMMARY

[0003] The present application provides a method, a terminal device and an access network device for wireless communication. The various aspects involved in the present application are introduced below.

[0004] In a first aspect, a method for wireless communication is provided, comprising: performing, by a terminal device, a handover operation, the handover operation comprising performing handover between a first access network device and a second access network device, wherein a radio access technology (RAT) corresponding to the first access network device is different from a RAT corresponding to the second access network device.

[0005] In a second aspect, a method for wireless communication is provided, comprising: sending, by a source access network device, a handover command to a terminal device, the handover command being used to instruct the terminal device to perform handover from the source access network device to a target access network device, a radio access technology (RAT) corresponding to the source access network device being different from a RAT corresponding to the target access network device.

[0006] In a third aspect, a method for wireless communication is provided, comprising: sending, by a target access network device, a handover request acknowledgement message to a source access network device, a handover command carried in the handover request acknowledgement message being used to instruct a terminal device to perform handover from the source access network device to the target access network device, a radio access technology (RAT) corresponding to the source access network device being different from a RAT corresponding to the target access network device.

[0007] In a fourth aspect, a terminal device is provided, comprising: a processing unit configured to perform a handover operation, the handover operation comprising performing handover between a first access network device and a second access network device, wherein a radio access technology (RAT) corresponding to the first access network device is different from a RAT corresponding to the second access network device.

[0008] Fifthly, an access network device is provided, the access network device being a source access network device, comprising: a transmitting unit for sending a handover command to a terminal device, the handover command being used to instruct the terminal device to switch from the source access network device to a target access network device, wherein the Radio Access Technology (RAT) corresponding to the source access network device is different from the RAT corresponding to the target access network device.

[0009] In a sixth aspect, an access network device is provided, the access network device being a target access network device, comprising: a sending unit, configured to send a handover request confirmation message to a source access network device, wherein the handover command carried in the handover request confirmation message is used to instruct a terminal device to handover from the source access network device to the target access network device, and the radio access technology (RAT) corresponding to the source access network device is different from the RAT corresponding to the target access network device.

[0010] In a seventh aspect, a terminal device is provided, including a processor, a memory, and a communication interface, wherein the memory is used to store one or more computer programs, and the processor is used to invoke the computer programs in the memory to cause the terminal device to perform some or all of the steps in the method of the first aspect.

[0011] Eighthly, a network device is provided, including a processor, a memory, and a transceiver, wherein the memory is used to store one or more computer programs, and the processor is used to invoke the computer programs in the memory to cause the network device to perform some or all of the steps in the method of the second aspect.

[0012] Ninthly, embodiments of this application provide a communication system including the aforementioned terminal device and / or network device. In another possible design, the system may further include other devices that interact with the terminal device or network device as described in the embodiments of this application.

[0013] In a tenth aspect, embodiments of this application provide a computer-readable storage medium storing a computer program that causes a communication device to perform some or all of the steps in the methods described above.

[0014] Eleventhly, embodiments of this application provide a computer program product, wherein the computer program product includes a non-transitory computer-readable storage medium storing a computer program operable to cause a communication device (e.g., a terminal device or a network device) to perform some or all of the steps of the methods described in the foregoing aspects. In some implementations, the computer program product may be a software installation package.

[0015] In a twelfth aspect, embodiments of this application provide a chip including a memory and a processor, the processor being able to call and run a computer program from the memory to implement some or all of the steps described in the methods of the foregoing aspects.

[0016] In this embodiment, the terminal device can switch between a first access network device and a second access network device. The RAT corresponding to the first access network device is different from the RAT corresponding to the second access network device, which helps to avoid connection interruption between the terminal device and the network. Attached Figure Description

[0017] Figure 1 shows the wireless communication system 100 used in an embodiment of this application.

[0018] Figure 2 is a schematic diagram of the traditional solution where 4G network access network equipment and 5G network access network equipment are connected to the same network.

[0019] Figures 3A and 3B are schematic diagrams of the protocol stack structure between the terminal device and the access network device.

[0020] Figure 4 is a schematic diagram of the communication architecture applicable to the embodiments of this application.

[0021] Figure 5 is a schematic diagram of a communication architecture applicable to another embodiment of this application.

[0022] Figures 6A and 6B are schematic diagrams of the protocol stack in the terminal device used for communication with the first access network device and the protocol stack of the first access network device in the embodiments of this application.

[0023] Figures 7A and 7B are schematic diagrams of the protocol stack in the terminal device for communicating with the first access network device and the protocol stack of the first access network device in another embodiment of this application.

[0024] Figures 8A and 8B are schematic diagrams of the protocol stack in the terminal device for communicating with the second access network device and the protocol stack of the second access network device in another embodiment of this application.

[0025] Figures 9A and 9B are schematic diagrams of the architecture of the protocol stack for communication with the second access network device and the protocol stack of the second access network device in the embodiments of this application.

[0026] Figures 10A and 10B are schematic diagrams of the architecture of the communication protocol stack for the first access network device and the protocol stack of the first access network device in the embodiments of this application.

[0027] Figures 11A, 11B, 12A, and 12B are schematic diagrams of a protocol stack including a first protocol layer in an embodiment of this application.

[0028] Figure 13 is a schematic flowchart of a wireless communication method according to an embodiment of this application.

[0029] Figure 14 is a schematic flowchart of the switching process according to an embodiment of this application.

[0030] Figure 15 is a schematic flowchart of the switching process according to another embodiment of this application.

[0031] Figure 16 is a schematic diagram of a terminal device according to an embodiment of this application.

[0032] Figure 17 is a schematic diagram of an access network device according to an embodiment of this application.

[0033] Figure 18 is a schematic diagram of an access network device according to an embodiment of this application.

[0034] Figure 19 is a schematic structural diagram of a communication device according to an embodiment of this application. Detailed Implementation

[0035] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0036] Figure 1 illustrates a wireless communication system 100 according to an embodiment of this application. The wireless communication system 100 may include a network device 110 and a terminal device 120. The network device 110 may be a device that communicates with the terminal device 120. The network device 110 may provide communication coverage for a specific geographical area and may communicate with the terminal device 120 located within that coverage area.

[0037] Figure 1 illustrates an exemplary network device and two terminals. Optionally, the wireless communication system 100 may include multiple network devices, and each network device may include other terminal devices within its coverage area. This application embodiment does not limit this.

[0038] Optionally, the wireless communication system 100 may also include other network entities such as a network controller and a mobility management entity, which is not limited in this embodiment.

[0039] It should be understood that the technical solutions of the embodiments of this application can be applied to various communication systems, such as: 5th generation (5G) systems or new radio (NR), long term evolution (LTE) systems, LTE frequency division duplex (FDD) systems, LTE time division duplex (TDD) systems, etc. The technical solutions provided in this application can also be applied to future communication systems, such as 6th generation mobile communication systems, satellite communication systems, and so on.

[0040] The terminal device in this application embodiment can also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station, mobile station (MS), mobile terminal (MT), remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device. The terminal device in this application embodiment can be a device that provides voice and / or data connectivity to a user, and can be used to connect people, objects, and machines, such as a handheld device with wireless connectivity, vehicle-mounted device, etc. The terminal devices in the embodiments of this application can be mobile phones, tablets, laptops, PDAs, mobile internet devices (MIDs), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, self-driving, remote medical surgery, smart grids, transportation safety, smart cities, and smart homes, etc. Optionally, the UE can act as a base station. For example, the UE can act as a scheduling entity, providing sidelink signals between UEs in V2X or D2D, etc. For example, cellular phones and cars communicate with each other using sidelink signals. Cellular phones and smart home devices communicate without relaying communication signals through a base station.

[0041] The network device in this application embodiment can be a device for communicating with a terminal device. This network device can also be called an access network device or a wireless access network device, such as a base station. In this application embodiment, the network device can refer to a radio access network (RAN) node (or device) that connects the terminal device to the wireless network. A base station can broadly encompass, or be replaced by, various names including: NodeB, evolved NodeB (eNB), next-generation NodeB (gNB), relay station, transmitting and receiving point (TRP), transmitting point (TP), master MeNB, auxiliary SeNB, multi-mode radio (MSR) node, home base station, network controller, access node, wireless node, access point (AP), transmission node, transceiver node, baseband unit (BBU), remote radio unit (RRU), active antenna unit (AAU), remote radio head (RRH), central unit (CU), distributed unit (DU), positioning node, etc. A base station can be a macro base station, micro base station, relay node, donor node, or similar, or a combination thereof. A base station can also refer to a communication module, modem, or chip installed within the aforementioned equipment or apparatus. Base stations can also be mobile switching centers, devices that perform base station functions in device-to-device (D2D), vehicle-to-everything (V2X), and machine-to-machine (M2M) communications, network-side devices in 6G networks, and devices that perform base station functions in future communication systems. Base stations can support networks using the same or different access technologies. The embodiments of this application do not limit the specific technologies or device forms used in the network equipment.

[0042] Base stations can be fixed or mobile. For example, a helicopter or drone can be configured to act as a mobile base station, and one or more cells can move depending on the location of the mobile base station. In other examples, a helicopter or drone can be configured as a device to communicate with another base station.

[0043] In some deployments, the network device in this application embodiment may refer to a CU or a DU, or the network device may include both a CU and a DU. The gNB may also include an AAU.

[0044] Network devices and terminal devices can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can also be deployed in the air on airplanes, balloons, and satellites. This application does not limit the scenario in which the network devices and terminal devices are located.

[0045] It should be understood that all or part of the functions of the communication device in this application can also be implemented by software functions running on hardware, or by virtualization functions instantiated on a platform (e.g., a cloud platform).

[0046] Intra-systeminter-RAT

[0047] When a new generation of technology emerges, the deployment of the new RAT (Real-Time Access Provider) needs to be rolled out commercially gradually, so the coverage of the new RAT network is initially relatively limited. At this time, when a terminal device carrying services on the new RAT leaves the new RAT network, it needs to switch to the legacy RAT network; otherwise, the terminal device will lose connection with the network. As the coverage of the new RAT network reaches a certain range, terminal devices will switch between the two networks due to the services and pricing offered by the new and legacy RAT networks. For example, when 4G networks were first deployed, because LTE could not yet provide VoIP services, devices needed to fall back to the 3G network to obtain voice services. When a terminal device needed to transmit data services, it would switch from the 3G network to the 4G network.

[0048] When 5G networks began to be deployed, standalone (SA) deployments were relatively successful, but they also faced similar upgrade cycles and handover issues with 4G networks. In one network architecture, 4G access network equipment and the 5G core network (5GC) are connected together.

[0049] As shown in Figure 2, both the 4G network access network equipment (eNB) and the 5G network access network equipment (gNB) are connected to the 5GC through the same Ng interface. Initially, the terminal device is connected to both the gNB and the 5GC. When the terminal device moves out of the gNB's coverage area, it gradually enters the eNB's coverage area. At this point, a handover occurs between different RATs within the same 5GC.

[0050] Some protocols (e.g., 3GPP TS 36.300) describe the protocol stack structure between the terminal device and the eNB when the eNB connects to the 5GC, as shown in Figures 3A and 3B. Figure 3A shows the user plane protocol stack. In the protocol stack shown in Figure 3A, the structure of the protocol stack between the terminal device and the access network device is similar. From top to bottom, it includes the Service Data Adaptation Protocol (SDAP) layer, the NR PDCP layer, the Radio Link Control (RLC) layer, the Media Access Control (MAC) layer, and the Physical (PHY) layer.

[0051] The SDAP layer is used for mapping between Quality of Service (QoS) streams and data radio bearers (DRBs). The NR PDCP layer implements one or more of the following functions: encryption / decryption; integrity protection; header compression and decompression; maintenance of PDCP send / receive sequence numbers; timer-based PDCP service data unit (SDU) discarding; routing functionality for split bearers; duplicate transmission functionality; and reordering and in-order delivery functionality. The RLC layer is used for RLC protocol data unit (PDU) packet segmentation, reassembly, and error detection. The MAC layer is used for mapping between logical and transport channels, multiplexing and demultiplexing, uplink / downlink scheduling procedures, and random access procedures. In some protocols, the MAC layer is also used for bandwidth part (BWP) activation / deactivation procedures and beam failure recovery procedures. The physical layer provides mechanical, electronic, functional, and specification characteristics for creating, maintaining, and dismantling the physical links required for data transmission.

[0052] Figure 3B illustrates the control plane protocol stack. In the control plane protocol stack shown in Figure 3B, the control plane protocol stack in the terminal equipment includes, from top to bottom, the following layers: Non-Access-Stratum (NAS) layer, Radio Resource Control (RRC) layer, PDCP layer, RLC layer, MAC layer, and PHY layer. The control plane protocol stack in the access network equipment includes, from top to bottom, the following layers: RRC layer, PDCP layer, RLC layer, MAC layer, and PHY layer. The control plane protocol stack in the core network equipment (e.g., AMF) includes the NAS layer.

[0053] The NAS layer is used to perform functions such as authentication, mobility management, and security control. The RRC layer is used for the control and management of the access network, and its main functions include broadcasting, paging, RRC management, radio bearer control, mobility management, QoS management, measurement reporting and control, radio link device monitoring and recovery, and NAS message transmission. The NR PDCP layer is used for functions such as encryption and decryption of RRC protocol data, integrity protection, and duplicate monitoring.

[0054] It should be noted that the SDAP layer and NR PDCP layer in the protocol stack shown in Figure 3A are the user plane protocol stack of 5G NR. This is done for two reasons: firstly, to allow the use of the Ng interface instead of the S1 interface (where the S1 interface is the interface between the eNB and the 4G core network EPC) when accessing the 5GC, thereby reducing the complexity of the core network; secondly, the 4G eNB can reuse the new QoS and security frameworks in the 5G NR system, enabling seamless handover between RATs within the system.

[0055] Currently, to achieve seamless handover (e.g., lossless and ordered downlink transmission), when the terminal device executes the handover command, the control parameters of the SDAP and PDCP layers first employ an incremental configuration (also known as "delta signaling") mechanism. This means the new configuration is a partial update based on the existing configuration. This control plane approach allows the user plane SDAP and PDCP entities to be updated during handover by re-establishing them, rather than by releasing and setting them up. The difference lies in the fact that when re-establishing SDAP and PDCP entities, the user plane entity's working context is preserved, while the release and setup process completely erases the working context, thus failing to achieve seamless handover.

[0056] As mentioned earlier, during the evolution of communication systems, access network equipment (also known as "next-generation access network equipment" or "next-generation base station") of next-generation communication systems and access network equipment (also known as "traditional access network equipment" or "legacy base station") of traditional communication systems are connected to the core network of the next-generation communication system (this core network can be understood as the core network adapted to the RAT corresponding to the access network equipment of the next-generation communication system, also known as the "next-generation core network"). However, connecting traditional access network equipment to the next-generation core network requires modification of the traditional access network equipment. On the one hand, modifying traditional access network equipment leads to increased costs. On the other hand, terminal equipment in traditional communication systems cannot connect to the modified traditional access network equipment. Therefore, the above-mentioned deployment method of connecting next-generation access network equipment and traditional access network equipment to the next-generation core network is not commercially successful.

[0057] For example, next-generation access network equipment is 5G access network equipment, while traditional access network equipment is 4G access network equipment. Referring to Figure 2, if 4G access network equipment is integrated into the 5G core network, it needs to be modified. On the one hand, modifying the 4G access network equipment increases costs. On the other hand, terminal devices in the 4G communication system cannot access the modified 4G access network equipment. Therefore, the deployment method of integrating 5G and 4G access network equipment into the 5G core network is not commercially successful. Furthermore, for the above reasons, the intra-system RAT handover schemes involved in the 3GPP specifications are rarely used in practical applications.

[0058] Therefore, to address the aforementioned issues, this application provides two communication architectures. In Architecture 1, the next-generation access network equipment can access the traditional core network, reducing the need for modifications to the traditional access network equipment and helping to lower the cost of such modifications. Furthermore, since the traditional access network equipment and the next-generation access network equipment access the same core network, it facilitates RAT handover within the system for the terminal equipment. For ease of understanding, the communication architecture of this application embodiment is described below with reference to Figure 4.

[0059] Referring to Figure 4, next-generation access network (NGN) devices and traditional access network (TDN) devices can connect to the traditional core network. In some implementations, NNGN devices and TDN devices can directly configure interfaces, which can be user plane interfaces, or interfaces that combine control plane and user plane interfaces. In some implementations, the interfaces between NNGN devices, TDN devices, and the traditional core network can include control plane interfaces and / or user plane interfaces.

[0060] In some implementations, the traditional core network can be an extension of the core network of a traditional communication system to support the core network of a new generation of RATs. Therefore, this core network is also called a "hybrid core network".

[0061] In Architecture 2, next-generation access network (NGN) devices and traditional access network (TNN) devices can each access their respective core networks. That is, NNGN devices access the NNGN core network, and TNN devices access the TNN core network. Correspondingly, control plane interfaces and user plane interfaces can be provided between the NNGN core network and the TNN core network. On the one hand, this helps assist terminal devices in achieving RAT (Regional Access Terminal) handover between NNGN and TNN devices; on the other hand, it helps reduce the need for modifications to TNN devices, thereby reducing the cost of such modifications. For ease of understanding, the communication architecture of this embodiment is described below with reference to Figure 5.

[0062] Referring to Figure 5, next-generation access network equipment connects to the next-generation core network, while traditional access network equipment connects to the traditional core network. In some implementations, a control plane interface and / or a user plane interface can be provided between the next-generation core network and the traditional core network. In other implementations, a user plane tunnel can be provided between the next-generation access network equipment and the traditional access network equipment.

[0063] It should be noted that this application does not limit the distinction between next-generation access network equipment and traditional access network equipment. In some implementations, next-generation access network equipment can be an access network equipment relative to traditional access network equipment. For example, next-generation access network equipment can be the next generation (NG) access network equipment of traditional access network equipment. Taking a 5G access network equipment as an example, the next-generation access network equipment is a 6G access network equipment. Taking a 4G access network equipment as an example, the next-generation access network equipment is a 5G access network equipment. Of course, in this application embodiment, the traditional access network equipment is a 4G access network equipment, and the next-generation access network equipment is a 6G access network equipment.

[0064] Currently, to support the two communication architectures described above, adjustments need to be made to the protocol stacks of terminal devices and / or access network devices. For ease of description, the next-generation access network device is referred to as the first access network device, and the traditional access network device as the second access network device. In some implementations, the first access network device is the next-generation access network device of the second access network device, and correspondingly, the RAT corresponding to the first access network device is the next-generation RAT of the RAT corresponding to the second access network device.

[0065] The following describes the protocol stacks of the terminal device and / or access network device (first access network device and second access network device) in the embodiments of this application. It should be noted that, since the terminal device in the embodiments of this application needs to communicate with the first access network device and the second access network device, the terminal device may include multiple protocol stacks that communicate with the first access network device and the second access network device respectively. Accordingly, the protocol stack in the first access network device refers to the protocol stack in the first access network device used for communication with the terminal device, and the protocol stack in the second access network device refers to the protocol stack in the second access network device used for communication with the terminal device.

[0066] In some implementations, the protocol stack in the terminal device used for communicating with the first access network device includes a first SDAP layer and / or a first PDCP layer.

[0067] In some implementations, the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device. That is to say, the first SDAP layer is a backward-compatible protocol layer based on the traditional SDAP layer. The traditional SDAP layer can be understood as the protocol layer in a traditional communication system, i.e., the protocol layer of the RAT corresponding to the second access network device mentioned above. Therefore, the first SDAP layer can also be called the "traditional SDAP layer".

[0068] In some implementations, backward compatibility is used to enable terminal devices to process information formats in next-generation communication systems. For example, in the user plane protocol stack, backward compatibility can be understood as access network devices that support the traditional SDAP protocol being able to correctly decode the data format transmitted by the SDAP layer of next-generation communication systems.

[0069] In some implementations, the first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device. That is to say, the first PDCP layer is a backward-compatible protocol layer based on the traditional PDCP layer. The traditional PDCP layer can be understood as the protocol layer in a traditional communication system, i.e., the protocol layer of the RAT corresponding to the second access network device mentioned above. Therefore, the first PDCP layer can also be called the "traditional PDCP layer".

[0070] In some implementations, backward compatibility is used to enable terminal devices to process information formats in next-generation communication systems. For example, in the control plane protocol stack, backward compatibility can be understood as access network devices supporting the traditional PDCP protocol being able to correctly decode the signaling formats (e.g., RRC message / cell formats) of the PDCP layer in next-generation communication systems. As another example, in the user plane protocol stack, backward compatibility can be understood as access network devices supporting the traditional PDCP protocol being able to correctly decode the data formats transmitted by the PDCP layer of next-generation communication systems.

[0071] In this embodiment, the protocol stack used for communicating with the first access network device may include a user plane protocol stack and / or a control plane protocol stack. In some implementations, for the user plane protocol stack, the terminal device's protocol stack includes a first SDAP layer and a first PDCP layer. In other implementations, for the control plane protocol stack, the terminal device's protocol stack includes a first PDCP layer.

[0072] In some implementations, the terminal device's protocol stack is a control plane protocol stack, which includes a second RRC layer. This second RRC layer corresponds to the RAT of the first access network device. In other words, the second RRC layer can be the RRC layer in a next-generation communication system, or the protocol of the second RRC layer is the RRC protocol in a next-generation communication system.

[0073] For ease of understanding, the following description, in conjunction with Figures 6A and 6B, introduces the protocol stack within the terminal device used for communication with the first access network device, and the protocol stack within the first access network device used for communication with the terminal device. Referring to the user plane protocol stack shown in Figure 6A, the user plane protocol stack within the terminal device used for communication with the first access network device (or, the user plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the traditional SDAP layer, the traditional PDCP layer, the NG RLC layer, the NG MAC layer, and the NG PHY layer. Correspondingly, the user plane protocol stack within the first access network device used for communication with the terminal device includes, from top to bottom, the traditional SDAP layer, the traditional PDCP layer, the NG RLC layer, the NG MAC layer, and the NG PHY layer.

[0074] Referring to the control plane protocol stack shown in Figure 6B, the control plane protocol stack within the terminal device that communicates with the first access network device (or, the control plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the NG RRC layer, the traditional PDCP layer, the NG RLC layer, the NG MAC layer, and the NG PHY layer. Correspondingly, the control plane protocol stack in the first access network device used for communication with the terminal device includes, from top to bottom, the NG RRC layer, the traditional PDCP layer, the NG RLC layer, the NG MAC layer, and the NG PHY layer.

[0075] In the protocol stacks shown in Figures 6A and 6B, the traditional SDAP layer can be understood as the protocol layer that supports the traditional SDAP protocol, and the traditional PDCP layer can be understood as the protocol layer that supports the traditional PDCP protocol. The NG RRC layer, NG RLC layer, NG MAC layer, and NG PHY layer can be understood as protocol layers that support the protocols specified in the next-generation communication system. In other words, the NG RRC layer, NG RLC layer, NG MAC layer, and NG PHY layer can be understood as a protocol stack designed for the RAT (i.e., the next-generation RAT) of the first access network device.

[0076] It should be noted that, in this embodiment, the traditional SDAP layer can also be understood as the protocol layer that supports the SDAP protocol of the RAT of the first access network device. That is to say, the traditional SDAP layer can be a backward-compatible extension based on the traditional SDAP protocol. Specifically, for the user plane protocol stack, the backward-compatible extension enables the SDAP layer supporting the traditional SDAP protocol to correctly decode the data formats supported by the RAT of the first access network device and to configure and run the traditional SDAP protocol layer according to the supported traditional SDAP protocol portion.

[0077] Furthermore, the traditional PDCP layer can also be understood as the protocol layer that supports the PDCP protocol of the RAT of the first access network device. That is to say, the traditional PDCP layer can be a backward-compatible extension based on the traditional PDCP protocol. Specifically, for the user plane protocol stack, the backward-compatible extension allows the PDCP layer supporting the traditional PDCP protocol to correctly decode the RRC message / cell format supported by the RAT of the first access network device, and to configure and run the traditional PDCP protocol layer according to the supported traditional PDCP protocol portion.

[0078] The above describes the implementation of the protocol stack for communication between the terminal device and the first access network device in the embodiments of this application. The following describes the implementation of the protocol stack for communication between the terminal device and the first access network device in another embodiment of this application.

[0079] In some implementations, for the user plane protocol stack, the protocol stack in the terminal device used to communicate with the first access network device includes the first SDAP layer.

[0080] In some implementations, the protocol stack (e.g., control plane protocol stack and / or user plane protocol stack) in the terminal device used for communication with the first access network device includes a second PDCP layer for communication with the first access network device. This second PDCP layer is the protocol layer of the RAT corresponding to the first access network device. In other words, the second PDCP layer is the PDCP layer in a next-generation communication system, or the protocol of the second PDCP layer is the PDCP protocol in a next-generation communication system. Therefore, the second PDCP layer is also called "NG PDCP".

[0081] In this embodiment of the application, for the protocol stack that communicates with the first access network device within the terminal device, except for the SDAP layer which adopts the traditional SDAP protocol, all other protocol layers can adopt the protocols specified in the next-generation communication system.

[0082] For ease of understanding, the following describes a protocol stack for communication between a terminal device and a first access network device in another embodiment of this application, with reference to Figures 7A and 7B. Referring to the user plane protocol stack shown in Figure 7A, the user plane protocol stack within the terminal device that communicates with the first access network device (or, the user plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the traditional SDAP layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer. Correspondingly, the user plane protocol stack in the first access network device that communicates with the terminal device includes, from top to bottom, the traditional SDAP layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer.

[0083] Referring to the control plane protocol stack shown in Figure 7B, the control plane protocol stack within the terminal device that communicates with the first access network device (or, the control plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the NG RRC layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer. Correspondingly, the control plane protocol stack in the first access network device used for communication with the terminal device includes, from top to bottom, the NG RRC layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer.

[0084] In some implementations, in order to enable seamless switching of terminal devices between multiple RATs, the length between the PDCP sequence number (SN) of the next-generation RAT and the PDCP SN of the traditional RAT is consistent, and / or the length between the PDLC hyperframe number (HFN) of the next-generation RAT and the PDCP HFN of the traditional RAT is consistent.

[0085] In the protocol stacks shown in Figures 7A and 7B, the traditional SDAP layer can be understood as the protocol layer that supports the traditional SDAP protocol. The NG RRC layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer can be understood as protocol layers that support the protocols specified in next-generation communication systems. In other words, the NG RRC layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer can be understood as a protocol stack designed for the RAT (i.e., next-generation RAT) of the first access network device.

[0086] It should be noted that, in this embodiment, the traditional SDAP layer can also be understood as the protocol layer that supports the SDAP protocol of the RAT of the first access network device. That is to say, the traditional SDAP layer can be a backward-compatible extension based on the traditional SDAP protocol. Specifically, for the user plane protocol stack, the backward-compatible extension enables the SDAP layer supporting the traditional SDAP protocol to correctly decode the data formats supported by the RAT of the first access network device and to configure and run the traditional SDAP protocol layer according to the supported traditional SDAP protocol portion.

[0087] As can be seen from the above introduction, in this embodiment, the PDCP layer supports the traditional PDCP protocol in the protocol stack used for communication between the terminal device and the first access network device. This is because the PDCP protocol is much more complex and has a greater correlation with the RAT. Keeping the PDCP protocol layer unchanged or making slight backward compatibility extensions helps to ensure that PDCP SDUs are not lost during the handover process and / or that PDCP SDUs are delivered in sequence, so as to achieve seamless handover of the terminal device between RATs.

[0088] As mentioned above, the terminal device needs to switch between the first access network device and the second access network device. Therefore, in addition to the protocol stack for communicating with the first access network device as described above, the terminal device may also include a protocol stack for communicating with the second access network device.

[0089] In some implementations, each protocol layer in the protocol stack used for communication between the terminal device and the second access network device can be a protocol layer from a traditional communication system. The following description uses Figures 8A and 8B as examples. Referring to the user plane protocol stack shown in Figure 8A, the user plane protocol stack within the terminal device that communicates with the second access network device (or, the user plane protocol stack between the terminal device and the RAT of the second access network device) includes, from top to bottom, the traditional SDAP layer, traditional PDCP layer, traditional RLC layer, traditional MAC layer, and traditional PHY layer. Correspondingly, the user plane protocol stack in the second access network device used for communication with the terminal device includes, from top to bottom, the traditional SDAP layer, traditional PDCP layer, traditional RLC layer, traditional MAC layer, and traditional PHY layer.

[0090] Referring to the control plane protocol stack shown in Figure 8B, the control plane protocol stack for communication between the terminal device and the second access network device (or, the control plane protocol stack between the terminal device and the RAT of the second access network device) includes, from top to bottom, the traditional RRC layer, traditional PDCP layer, traditional RLC layer, traditional MAC layer, and traditional PHY layer. Correspondingly, the control plane protocol stack in the second access network device for communication with the terminal device includes, from top to bottom, the traditional RRC layer, traditional PDCP layer, traditional RLC layer, traditional MAC layer, and traditional PHY layer.

[0091] In the protocol stacks shown in Figures 8A and 8B, if the terminal device is connected to a traditional RAT, the user plane protocol stack and control plane protocol stack of the traditional RAT can be fully adopted on the wireless interface.

[0092] The foregoing section described the improvements to the protocol stack of the terminal device and / or the first access network device in the embodiments of this application, to support the switching of the terminal device between the first access network device and the second access network device. Of course, in the embodiments of this application, the protocol stack in the terminal device used for communication with the second access network device and / or the protocol stack of the second access network device can also be adjusted to support the switching of the terminal device between the first access network device and the second access network device.

[0093] In some implementations, the protocol stack in the terminal device used for communication with the second access network device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device. That is to say, the second SDAP layer is the SDAP layer in a next-generation communication system, or the protocol of the second SDAP layer is the SDAP protocol in a next-generation communication system. Therefore, the second SDAP layer is also called "NG SDAP".

[0094] It should be noted that, except for the second SDAP layer, all other protocol layers in the protocol stack used for communication with the second access network device within the terminal device can be configured based on the protocols of each layer in the traditional communication system.

[0095] In this embodiment, the SDAP layer in the protocol stack of the terminal device used for communication with the second access network device can be set as the second SDAP layer. Thus, in next-generation communication systems, the SDAP layer can adopt a completely new design to improve system performance. For the protocol stack used for communication with the second access network device, or for the protocol stack of the second access network device itself, only the SDAP layer protocol needs to be modified. Since the SDAP layer protocol is relatively simple, the workload for improving the SDAP layer is relatively small.

[0096] In some implementations, the control plane protocol stack in the terminal device used for communication with the second access network device includes a first RRC layer, which corresponds to the RAT of the second access network device. That is to say, the first RRC layer is the RRC layer in a traditional communication system, or the protocol of the first RRC layer is the RRC protocol in a traditional communication system. Therefore, the first RRC layer is also called the "traditional RRC layer".

[0097] It should be noted that the structure of the communication protocol stack in the terminal device in the embodiments of this application is the same as the structure of the protocol stack in the second access network device for communicating with the terminal device. For the sake of simplicity, it will not be described again here.

[0098] For ease of understanding, the architecture of the communication protocol stack between the terminal device and the second access network device in this embodiment is described below with reference to Figures 9A and 9B. Referring to the user plane protocol stack shown in Figure 9A, the user plane protocol stack within the terminal device that communicates with the second access network device (or, the user plane protocol stack between the terminal device and the RAT of the second access network device) includes, from top to bottom, the NG SDAP layer, the traditional PDCP layer, the traditional RLC layer, the traditional MAC layer, and the traditional PHY layer. Correspondingly, the user plane protocol stack in the second access network device that communicates with the terminal device includes, from top to bottom, the NG SDAP layer, the traditional PDCP layer, the traditional RLC layer, the traditional MAC layer, and the traditional PHY layer.

[0099] Referring to the control plane protocol stack shown in Figure 9B, the control plane protocol stack for communication between the terminal device and the second access network device (or, the control plane protocol stack between the terminal device and the RAT of the second access network device) includes, from top to bottom, the traditional RRC layer, traditional PDCP layer, traditional RLC layer, traditional MAC layer, and traditional PHY layer. Correspondingly, the control plane protocol stack in the second access network device used for communication with the terminal device includes, from top to bottom, the traditional RRC layer, traditional PDCP layer, traditional RLC layer, traditional MAC layer, and traditional PHY layer.

[0100] In the protocol stacks shown in Figures 9A and 9B, the NG SDAP layer can be understood as a protocol layer that supports the protocols specified in next-generation communication systems. The traditional RRC layer, traditional PDCP layer, traditional RLC layer, traditional MAC layer, and traditional PHY layer can be understood as protocol layers that support the protocols specified in traditional communication systems. In other words, the traditional RRC layer, traditional PDCP layer, traditional RLC layer, traditional MAC layer, and traditional PHY layer can be understood as a protocol stack designed for the RAT (i.e., traditional RAT) of the second access network device.

[0101] As mentioned above, the terminal device needs to switch between the first access network device and the second access network device. Therefore, in addition to the protocol stack for communicating with the second access network device as described above, the terminal device may also include a protocol stack for communicating with the first access network device.

[0102] In some implementations, each protocol layer in the protocol stack used for communication between the terminal device and the first access network device can adopt protocol layers from next-generation communication systems. The following description uses Figures 10A and 10B as examples. Referring to the user plane protocol stack shown in Figure 10A, the user plane protocol stack within the terminal device that communicates with the first access network device (or, the user plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the NG SDAP layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer. Correspondingly, the user plane protocol stack in the first access network device used for communication with the terminal device includes, from top to bottom, the NG SDAP layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer.

[0103] Referring to the control plane protocol stack shown in Figure 10B, the control plane protocol stack within the terminal device that communicates with the first access network device (or, the control plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the NG RRC layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer. Correspondingly, the control plane protocol stack in the first access network device used for communication with the terminal device includes, from top to bottom, the NG RRC layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer.

[0104] In the protocol stacks shown in Figures 10A and 10B, the NG SDAP layer, NG RRC layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer can be understood as protocol layers that support the protocols specified in the next-generation communication system. In other words, the NG SDAP layer, NG RRC layer, NG PDCP layer, NG RLC layer, NG MAC layer, and NG PHY layer can be understood as a protocol stack designed for the RAT (i.e., the next-generation RAT) of the first access network device.

[0105] In some scenarios, some or all of the functions of the PDCP layer and the RLC layer can be merged and implemented by a newly introduced protocol layer (also known as the first protocol layer). Therefore, the first protocol layer is also called the "PDLC layer".

[0106] In some implementations, in the protocol stack used for communication between the terminal device and the first access network device, the first protocol layer is the protocol layer of the RAT corresponding to the first access network device. That is to say, the first protocol layer is the protocol layer in the next-generation communication system, or the protocol of the first protocol layer is the protocol in the next-generation communication system. Therefore, the first protocol layer is also called the "NG PDLC layer".

[0107] In some implementations, the length of the SN in the first protocol layer communicating with the source access network device is the same as the length of the SN in the protocol layer communicating with the target access network device, and / or the length of the HFN in the first protocol layer communicating with the source access network device is the same as the length of the HFN in the protocol layer communicating with the target access network device.

[0108] In some implementations, the first protocol layer in the protocol stack of the terminal device or the protocol stack of the second access network device is located between the SDAP layer and the MAC layer. The SDAP layer is either the first SDAP layer or the second SDAP layer described above, as shown in Figures 11A, 11B, 12A, and 12B below.

[0109] For ease of understanding, the architecture of the protocol stack including the first protocol layer in the embodiments of this application is described below with reference to Figures 11A and 11B. Referring to the user plane protocol stack shown in Figure 11A, the user plane protocol stack in the terminal device that communicates with the first access network device (or, the user plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the NG SDAP layer, the NG PDLC layer, the NG MAC layer, and the NG PHY layer. Correspondingly, the user plane protocol stack in the first access network device used for communication with the terminal device includes, from top to bottom, the NG SDAP layer, the NG PDLC layer, the NG MAC layer, and the NG PHY layer.

[0110] Referring to the control plane protocol stack shown in Figure 11B, the control plane protocol stack within the terminal device that communicates with the first access network device (or, the control plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the NG RRC layer, NG PDLC layer, NG MAC layer, and NG PHY layer. Correspondingly, the control plane protocol stack in the first access network device used for communication with the terminal device includes, from top to bottom, the NG RRC layer, NG PDLC layer, NG MAC layer, and NG PHY layer.

[0111] In some implementations, the NG PDLC layer can be understood as a protocol layer that combines and improves upon some redundant functions of the PDCP and RLC layers. The NG PDLC layer may include sequence number information (e.g., PDLC SN) and / or the HFN context of the PDLC entity in the PDU header. Typically, to enable seamless handover of terminal devices between multiple RATs, the length between the PDLC SN of the next-generation RAT and the PDCP SN of the traditional RAT is consistent, and / or the length between the PDLC HFN of the next-generation RAT and the PDCP HFN of the traditional RAT is consistent.

[0112] In the protocol stacks shown in Figures 11A and 11B, the NG SDAP layer, NG RRC layer, NG PDLC layer, NG MAC layer, and NG PHY layer can be understood as protocol layers that support the protocols specified in the next-generation communication system. Alternatively, the NG SDAP layer, NG RRC layer, NG PDLC layer, NG MAC layer, and NG PHY layer can be understood as a protocol stack designed for the RAT (i.e., the next-generation RAT) of the first access network device.

[0113] As mentioned above, the terminal device needs to switch between the first access network device and the second access network device. Therefore, in addition to the protocol stack for communicating with the first access network device as described above, the terminal device may also include a protocol stack for communicating with the second access network device.

[0114] In some implementations, each protocol layer in the protocol stack used for communication with the second access network device can be a protocol layer from a traditional communication system. For example, the protocol stack framework shown in Figures 9A and 9B can be used.

[0115] For ease of understanding, the architecture of the protocol stack including the first protocol layer in the embodiments of this application is described below with reference to Figures 12A and 12B. Referring to the user plane protocol stack shown in Figure 12A, the user plane protocol stack in the terminal device that communicates with the first access network device (or, the user plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the traditional SDAP layer, the NG PDLC layer, the NG MAC layer, and the NG PHY layer. Correspondingly, the user plane protocol stack in the first access network device used for communication with the terminal device includes, from top to bottom, the traditional SDAP layer, the NG PDLC layer, the NG MAC layer, and the NG PHY layer.

[0116] Referring to the control plane protocol stack shown in Figure 12B, the control plane protocol stack within the terminal device that communicates with the first access network device (or, the control plane protocol stack between the terminal device and the RAT of the first access network device) includes, from top to bottom, the NG RRC layer, NG PDLC layer, NG MAC layer, and NG PHY layer. Correspondingly, the control plane protocol stack in the first access network device used for communication with the terminal device includes, from top to bottom, the NG RRC layer, NG PDLC layer, NG MAC layer, and NG PHY layer.

[0117] In some implementations, the NG PDLC layer can be understood as a protocol layer that combines and improves upon some redundant functions of the PDCP and RLC layers. The NG PDLC layer may include sequence number information (e.g., PDLC SN) and / or the HFN context of the PDLC entity in the PDU header. Typically, to enable seamless handover of terminal devices between multiple RATs, the length between the PDLC SN of the next-generation RAT and the PDCP SN of the traditional RAT is consistent, and / or the length between the PDLC HFN of the next-generation RAT and the PDCP HFN of the traditional RAT is consistent.

[0118] In the protocol stacks shown in Figures 12A and 12B, the traditional SDAP layer can be understood as the protocol layer that supports the traditional SDAP protocol. The NG RRC layer, NG PDLC layer, NG MAC layer, and NG PHY layer can be understood as protocol layers that support the protocols specified in next-generation communication systems. In other words, the NG SDAP layer, NG RRC layer, NG PDLC layer, NG MAC layer, and NG PHY layer can be understood as a protocol stack designed for the RAT (i.e., next-generation RAT) of the first access network device.

[0119] As mentioned above, the terminal device needs to switch between the first access network device and the second access network device. Therefore, in addition to the protocol stack for communicating with the first access network device as described above, the terminal device may also include a protocol stack for communicating with the second access network device.

[0120] In some implementations, each protocol layer in the protocol stack used for communication between the terminal device and the second access network device can be a protocol layer from a traditional communication system. For example, the protocol stack framework shown in Figures 8A and 8B can be used.

[0121] The protocol stack provided in the embodiments of this application has been introduced above. The handover process of the terminal device implemented based on the above protocol stack is described below. Figure 13 is a schematic flowchart of the wireless communication method according to an embodiment of this application. The method shown in Figure 13 includes step S1310.

[0122] In step S1310, the terminal device performs a handover operation, which includes switching between the first access network device and the second access network device.

[0123] In some implementations, switching between the first access network device and the second access network device may include a terminal device switching from the first access network device to the second access network device. In this case, the source access network device can be the first access network device, and the target access network device can be the second access network device. Of course, in the embodiments of this application, switching between the first access network device and the second access network device may include a terminal device switching from the second access network device to the first access network device. In this case, the source access network device can be the second access network device, and the target access network device can be the first access network device.

[0124] In some implementations, the above method further includes: a terminal device receiving a handover command sent by a source access network device, the handover command indicating configuration information for communication between the SDAP layer and / or PDCP layer of the target access network device, the configuration information carrying incremental configuration information based on the configuration information of the SDAP layer and / or PDCP layer of the source access network device. In the embodiments of this application, this configuration scheme based on incremental configuration information helps to reduce the overhead of transmitting configuration information.

[0125] It should be noted that, for the protocol stack described above, the SDAP layer for communication of the target access network device can be either the first SDAP layer or the second SDAP layer. Correspondingly, the PDCP layer for communication of the target access network device can also be either the first PDCP layer or the second PDCP layer.

[0126] Accordingly, for the protocol stack described above, the SDAP layer for communication between the source access network devices can be either the first SDAP layer or the second SDAP layer. Similarly, the PDCP layer for communication between the source access network devices can be either the first PDCP layer or the second PDCP layer.

[0127] In some implementations, the handover command is sent by the target access network device to the source access network device. That is, the method also includes: the target access network device sending a handover request confirmation message to the source access network device, which carries the handover command.

[0128] In some implementations, the configuration information of the SDAP layer and / or PDCP layer for communication between the source access network device and the target access network device can be sent by the source access network device to the target access network device. For example, the above method further includes: the source access network device sending a handover request to the target access network device, the handover request carrying the configuration information of the source access network device's SDAP layer and / or PDCP layer.

[0129] In some implementations, the above method further includes: the terminal device obtaining configuration information for communicating with the target access network device based on incremental configuration information and configuration information of the SDAP layer and / or PDCP layer for communicating with the source access network device.

[0130] In some implementations, the above method further includes: the source access network device sending first information to the target access network device, the first information carrying one or more of the following: a PDCP SDU to be sent; a received PDCP SDU; a sent but not yet acknowledged PDCP SDU; a count (COUNT) value associated with the sent but not yet acknowledged PDCP SDU; the COUNT value of the first PDCP SDU to be allocated; and status information of the PDCP SDU to be received, wherein the status information is used to indicate whether the PDCP SDU has been successfully received. That is, the source access network device can send the first information to the target access network device so that after the terminal device switches to the target access network device, the target access network device can continue to transmit data to the terminal device, thereby reducing the impact of the handover operation performed by the terminal device on the smoothness of data transmission.

[0131] In some implementations, the aforementioned COUNT value is also called the "PDCP COUNT value." It is an important parameter in the PDCP layer used for security protection and data transmission, ensuring the uniqueness of each PDCP PDU. Typically, the COUNT value is a 32-bit unsigned value, comprising two parts: HFN and SN (also known as the "PDCP SN"). The length of HFN is equal to 32 minus the length of SN. Furthermore, after one cycle of the sequence number space, HFN is incremented by 1. For example, if SN is 12 bits, then the sequence number space is 0 to (2^32 - 2^32)^32. 12 -1), which is {0,4095}. When the sequence number increases from 0 to 4095, adding 1 to the sequence number will make it 0 again. At this time, HFN will be incremented by 1.

[0132] It should be noted that, in the embodiments of this application, the above-mentioned COUNT value can be used as the COUNT value of the first protocol layer PDU (PDLC PDU) in the following text.

[0133] In some implementations, the above method further includes: the terminal device retaining one or more of the following: the PDCP SDU received from the source access network device, the SN context of the PDCP entity associated with the source access network device, and the HFN context of the PDCP entity associated with the source access network device, so that after the terminal device switches from the source access network device to the target access network device, it can continue to receive the PDCP SDU to be transmitted to the terminal device sent by the source access network device to the target access network device, thereby reducing the impact of the handover operation performed by the terminal device on the smoothness of data transmission.

[0134] In some implementations, the SN context and HFN context of the PDCP entity are used to indicate one or more of the following: the COUNT value of the allocated PDCP SDU, the COUNT value of the next PDCP SDU to be allocated, and the COUNT value of the received PDCP SDU.

[0135] In some implementations, the switching command carries configuration information for one or more protocol layers. The one or more protocol layers are protocol layers of the terminal device other than the SDAP layer and / or PDCP layer that communicate with the target access network device. The above method also includes: the terminal device replacing the current configuration information of one or more protocol layers with the configuration information of one or more protocol layers.

[0136] For ease of understanding, the handover process of this application embodiment is described below with reference to Figure 14, assuming that the source access network device is the first access network device and the target access network device is the second access network device. Alternatively, the target access network device is the first access network device and the source access network device is the second access network device. The handover process shown in Figure 14 includes steps S1410 to S1460.

[0137] In step S1410, the terminal device establishes a connection with the source access network device.

[0138] In step S1415, the terminal device sends a measurement report to the source access network device.

[0139] In step S1420, the source access network device determines whether to perform a handover operation based on the measurement report.

[0140] In step S1425, if it is determined that a handover operation will be performed, the source access network device sends a handover request message to the target access network device.

[0141] In some implementations, the access service context (AS CONTEXT) in the handover request message includes the RRC configuration information of the terminal device on the access stratum (AS layer) of the source access network device. This configuration information includes the configuration information of the traditional SDAP layer and the traditional PDCP layer.

[0142] It should be noted that if the source access network device is an access network device that supports the next-generation RAT (i.e., the first access network device introduced above), then the above configuration information may also include some backward compatibility extension-related configurations.

[0143] In step S1430, the target access network device generates a handover command (HO CMD).

[0144] In some implementations, the handover command is carried in a handover request acknowledge (HO REQUEST ACK) message and sent to the target access network device. The HO CMD uses incremental configuration to generate delta signaling for both the SDAP and PDCP layers. Taking the PDCP layer protocol as an example, logically, the traditional PDCP configuration and the incremental PDCP configuration generated by the target access network device are combined to form the complete RRC configuration for the PDCP layer configured by the target access network device for the terminal device. Similarly, logically, the traditional SDAP configuration and the incremental SDAP configuration generated by the target access network device are combined to form the complete SDAP layer configuration configured by the target access network device for the terminal device.

[0145] It should be noted that using incremental signaling for configuration helps ensure continuity of DRB configuration before and after the handover. In the current 3GPP protocol, DRB configuration mainly refers to SDAP configuration and PDCP configuration.

[0146] In step S1435, the target access network device sends a handover request confirmation message to the source access network device, which carries the aforementioned handover command.

[0147] In step S1440, the source access network device sends a user plane context (UP CONTEXT) to the target access network device.

[0148] In some implementations, the user plane context contains all the state and configuration information required for the terminal device to transmit data in the network, enabling the terminal device to maintain data continuity when seamlessly switching between different network nodes.

[0149] In some implementations, to achieve seamless handover, the source access network device can send the PDCP layer context (e.g., SN context and / or HFN context) to the target access network device, and forward PDCP SDUs that have been sent but not acknowledged by the receiver (in this case, these SDUs have been assigned PDCP SNs), as well as unsent downlink PDCP SDUs and some uplink PDCP SDUs (e.g., PDCP SDUs not received in order by the receiver) to the target access network device through the user-facing forwarding tunnel. In some scenarios, the aforementioned PDCP SDUs can be understood as SDAP PDUs.

[0150] In some implementations, both the source access network device's RAT and the target access network device's RAT use the same or compatible SDAP and PDCP protocols, and therefore the aforementioned PDCP SDUs employ the same data format, thus maintaining compatibility between the two RATs. For the same reason, the PDCP SN and PDCP HFN maintain the same length for both the source and target access network devices.

[0151] It should be noted that if the PDCP PDU format used by the new generation RAT is different from that used by the traditional RAT, then this difference is backward compatible.

[0152] In step S1445, the source access network device forwards data to the target access network device. Data forwarding is a crucial step in the handover process, ensuring data continuity for the terminal device when switching from the source access network device to the target access network device.

[0153] In step S1450, the source access network device sends a handover command to the terminal device.

[0154] In step S1455, the terminal device processes the switching command.

[0155] In some implementations, the above processing includes configuration parameters for the PDCP layer protocol. The terminal device can combine the current PDCP configuration and the received incremental PDCP configuration to obtain the complete PDCP configuration configured by the target access network device for the terminal device. The same method is used for the configuration of the SDAP layer. For example, in the SDAP layer protocol, the mapping relationship between QoS flows and DRBs can remain unchanged for SDAP entities for the same PDU session before and after handover (i.e., the same SDAP entities before and after handover). Of course, in the embodiments of this application, for SDAP entities for the same PDU session before and after handover, the mapping between QoS flows and DRBs is remapping.

[0156] In some implementations, within the user plane protocol stack, for SDAP and PDCP layer entities configured using incremental configuration, the terminal device retains the current working context. When a PDCP layer entity switches, a PDCP entity re-establishment process occurs, such as a change in the security key. Furthermore, the terminal device can retain the SN context and HFN context of the sender and / or receiver's PDCP entities. The SN context and HFN context are used to indicate one or more of the following: the COUNT value of the allocated PDCP SDU, the COUNT value of the next PDCP SDU to be allocated, and the COUNT value of the received PDCP SDU.

[0157] In some implementations, for protocol layers below the PDCP layer, the terminal device uses HO CMD configuration to replace the current configuration information. At protocol layers below the PDCP layer, the terminal device first releases the protocol layer entity and then re-establishes it.

[0158] In step S1460, the terminal device connects to the target access network device and completes the handover operation.

[0159] It should be noted that the above description is from the perspectives of the terminal device, the source access network device, and the target access network device. The routing methods for control plane signaling and user plane data packets are directly related to the network architecture, but the network-side routing methods are transparent to the terminal device. In other words, from the terminal device's perspective, there is no difference on the wireless interface.

[0160] For example, for the architecture shown in Figure 4, network-side transmission can be divided into two schemes: Scheme 1 and Scheme 2. In Scheme 1, signaling exchange between the source access network device and the target access network device can be performed through the interface between the access network devices. The source access network device also forwards the PDCP SDU to the target access network device through the forwarding channel between the access network devices.

[0161] In Scheme 2, signaling exchange between the source access network device and the target access network device can be conducted through the core network. The source access network device can forward PDCP SDUs to the target access network device through the forwarding channel between access network devices. It should be understood that the content of the signaling may be partially updated during transmission through the core network; that is, message routing is not transparent.

[0162] For example, regarding the architecture shown in Figure 5, network-side transmission can be divided into two schemes: Scheme 3 and Scheme 4. In Scheme 3, the source access network device and / or the target access network device first send signaling to their respective connected core networks. The core networks interact through inter-core network interfaces, and then send the signaling to the access network devices connected to each core network. The source access network device can forward the PDCP SDU to the target access network device through the forwarding channel between access network devices. It should be understood that when the signaling passes through the core network, its content may be partially updated; that is, message routing is not transparent.

[0163] In Scheme 4, the source access network device and / or the target access network device first send signaling to their respective connected core networks. The core networks interact through inter-core network interfaces, and then the core networks forward the signaling to their respective connected access network devices. The source access network device forwards the PDCP SDU to the target access network device through a forwarding channel between core networks. It should be understood that the content of the signaling may be partially updated when it passes through the core network; that is, message routing is not transparent.

[0164] It should be noted that the handover process described above applies to protocol stacks that include both the first SDAP layer (i.e., the traditional SDAP layer) and the first PDCP layer (i.e., the traditional PDCP layer), such as the protocol stacks shown in Figures 6A and 6B. For protocol stacks that only include the first SDAP layer (i.e., the traditional SDAP layer), the handover process is similar, except that in step S1455, for the user plane protocol stack, the terminal device does not need to retain the current working context of the SDAP layer entity. In other scenarios, the protocol stack may include a first protocol layer; accordingly, the handover process may differ slightly.

[0165] In some implementations, the handover operation includes switching from the second access network device to the first access network device. The above method also includes: the terminal device replacing the configuration information of other protocol layers in the protocol stack used for control plane transmission, except for the first SDAP layer, with the configuration information carried in the handover command.

[0166] In some implementations, the handover operation includes switching from the second access network device to the first access network device. The above method also includes: the terminal device releasing the protocol entities of other protocol layers in the protocol stack used for user plane transmission, except for the first SDAP layer, and establishing protocol entities of other protocol layers used for communication with the first access network device.

[0167] In some implementations, the other protocol layers in the protocol stack used for control plane transmission include one or more of the first protocol layer, MAC layer, and PHY layer; or the protocol entities of the other protocol layers in the protocol stack used for user plane transmission include one or more of the following: protocol entity of PDCP layer, protocol entity of RLC layer, protocol entity of MAC layer, and protocol entity of PHY layer.

[0168] In some other implementations, the handover operation includes switching from a first access network device to a second access network device. The above method also includes: the terminal device replacing the configuration information of other protocol layers in the protocol stack used for control plane transmission, excluding the first SDAP layer, with the configuration information carried in the handover command.

[0169] In some implementations, the handover operation includes switching from the second access network device to the first access network device. The above method also includes: the terminal device releasing the protocol entities of other protocol layers in the protocol stack used for user plane transmission, except for the first SDAP layer, and establishing protocol entities of other protocol layers used for communication with the second access network device.

[0170] In some implementations, the protocol entities of other protocol layers in the protocol stack used for control plane transmission include one or more of the following: PDCP layer, RLC layer, MAC layer, and PHY layer; or the protocol entities of other protocol layers in the protocol stack used for user plane transmission include one or more of the following: protocol entity of PDCP layer, protocol entity of RLC layer, protocol entity of MAC layer, and protocol entity of PHY layer.

[0171] In some implementations, the above method further includes: the terminal device retaining one or more of the following: a first protocol layer SDU received from the source access network device, an SN context of a first protocol layer entity associated with the source access network device, and an HFN context of the first protocol layer entity, so that after the terminal device switches from the source access network device to the target access network device, it can continue to receive SDUs to be transmitted to the terminal device sent by the source access network device to the target access network device, thereby reducing the impact of the handover operation performed by the terminal device on the smoothness of data transmission.

[0172] In some implementations, the SN context and HFN context are used to indicate one or more of the following: the COUNT value of the first protocol layer SDU that has been assigned, the COUNT value of the next first protocol layer SDU to be assigned, the COUNT value of the first protocol layer SDU that has been received, the COUNT value of the next SDU that is expected to be received, the COUNT value of the first SDU that has not been delivered to the higher protocol layer, and the COUNT value of the SDU associated with starting the reordering timer.

[0173] In some implementations, the above method further includes: the source access network device sending second information to the target access network device, the second information carrying the SDU of the first protocol layer and / or the COUNT value corresponding to the SDU of the first protocol layer.

[0174] It should be noted that if the handover operation includes switching from the first access network device to the second access network device, the protocol stack of the first access network device is set to the first protocol layer, and the protocol stack of the second access network device is set to the traditional PDCP layer. Accordingly, the first protocol layer SDU is the PDCP layer SDU, the SN corresponding to the first protocol layer SDU is the SN corresponding to the PDCP layer SDU, and the HFN corresponding to the first protocol layer SDU is the HFN corresponding to the PDCP layer SDU.

[0175] For ease of understanding, the handover process of another embodiment of this application is described below with reference to Figure 15. Assume the source access network device is the second access network device, the target access network device is the first access network device, and the protocol stack of the first access network device is shown in Figures 11A and 11B; correspondingly, the protocol stack of the second access network device is shown in Figures 9A and 9B. The handover process shown in Figure 15 includes steps S1510 to S1560.

[0176] In step S1510, the terminal device establishes a connection with the source access network device.

[0177] In step S1515, the terminal device sends a measurement report to the source access network device.

[0178] In step S1520, the source access network device determines whether to perform a handover operation based on the measurement report.

[0179] In step S1525, if it is determined that a handover operation will be performed, the source access network device sends a handover request message to the target access network device.

[0180] In some implementations, the access service context (AS CONTEXT) in the handover request message includes the RRC configuration information of the terminal device on the access stratum (AS layer) of the source access network device. This configuration information includes the configuration information of the traditional SDAP layer and the traditional PDCP layer.

[0181] It should be noted that if the source access network device is an access network device that supports the next-generation RAT (i.e., the first access network device introduced above), then the above configuration information may also include some backward compatibility extension-related configurations.

[0182] In step S1530, the target access network device generates a handover command (HO CMD).

[0183] In some implementations, the handover command is carried in a handover request acknowledge (HO REQUEST ACK) message and sent to the target access network device. The HO CMD uses incremental configuration to generate delta signaling for the SDAP layer. Taking the SDAP layer protocol as an example, logically, the traditional SDAP configuration and the incremental SDAP configuration generated by the target access network device are combined to form the complete SDAP layer configuration configured by the target access network device for the terminal device.

[0184] It should be noted that using incremental signaling for configuration helps ensure continuity of DRB-level configuration before and after the handover. In the current 3GPP protocol, DRB configuration mainly refers to SDAP configuration.

[0185] In step S1535, the target access network device sends a handover request confirmation message to the source access network device, which carries the aforementioned handover command.

[0186] In step S1540, the source access network device sends a user plane context (UP CONTEXT) to the target access network device.

[0187] In some implementations, the user plane context contains all the state and configuration information required for the terminal device to transmit data in the network, enabling the terminal device to maintain data continuity when seamlessly switching between different network nodes.

[0188] In some implementations, to achieve seamless handover, the source access network device can send the PDCP layer context (e.g., SN context and / or HFN context) to the target access network device, and forward PDCP SDUs that have been sent but not acknowledged by the receiver (in this case, these SDUs have been assigned PDCP SNs), as well as unsent downlink PDCP SDUs and some uplink PDCP SDUs (e.g., PDCP SDUs not received in order by the receiver) to the target access network device through the user-facing forwarding tunnel. In some scenarios, the aforementioned PDCP SDUs can be understood as SDAP PDUs.

[0189] It should be noted that, for the target access network device, the context of the PDCP layer mentioned above can be applied to the PDLC layer of the target access network device. Accordingly, the PDLC SN can correspond to the PDCP SN, and the PDLC HFN can correspond to the PDCP HFN.

[0190] In some implementations, both the source access network device's RAT and the target access network device's RAT use the same or compatible SDAP protocol, and therefore the aforementioned SDAP SDUs employ the same data format, maintaining compatibility between the two RATs. For the same reason, the PDCP SN and PDLC HFN maintain the same length for both the source and target access network devices.

[0191] In step S1545, the source access network device forwards data to the target access network device. Data forwarding is a crucial step in the handover process, ensuring data continuity for the terminal device when switching from the source access network device to the target access network device.

[0192] In step S1550, the source access network device sends a handover command to the terminal device.

[0193] In step S1555, the terminal device processes the handover command.

[0194] In some implementations, the above processing includes configuration parameters for the SDAP layer protocol. The terminal device can combine the current SDAP configuration and the received incremental SDAP configuration to obtain the complete SDAP configuration configured by the target access network device for the terminal device. For example, in the SDAP layer protocol, the mapping relationship between QoS flows and DRBs can remain unchanged for SDAP entities for the same PDU session before and after the handover (i.e., the same SDAP entities before and after the handover). Of course, in the embodiments of this application, the mapping between QoS flows and DRBs is remapping for SDAP entities for the same PDU session before and after the handover.

[0195] In some implementations, for the control plane protocol stack, the terminal device can use the PDLC layer configuration information, RLC layer configuration information, MAC layer configuration information and PHY layer configuration information carried in the handover command for configuration.

[0196] For the user plane protocol stack, the terminal device can release the PDCP layer protocol entity, MAC layer protocol entity, and PHY layer protocol entity, and establish the PDLC layer protocol entity, RLC layer protocol entity, MAC layer protocol entity, and PHY layer protocol entity. When releasing the PDCP layer protocol entity, the PDCP SDU (i.e., SDAP PDU) and its corresponding SN / HFN are retained. At this time, the PDCP SDU can be used as a PDLC SDU.

[0197] In step S1560, the terminal device connects to the target access network device and completes the handover operation.

[0198] It should be noted that the above description uses the source access network device as the second access network device and the target access network device as the first access network device as an example. In other scenarios, the source access network device is the first access network device and the target access network device is the second access network device. For example, the protocol stack of the first access network device is shown in Figures 11A and 11B, and correspondingly, the protocol stack of the second access network device is shown in Figures 9A and 9B. In this case, the terminal device's processing of the handover command (see step S1555) differs slightly from the description above.

[0199] In some implementations, the terminal device handles the SDAP layer in the same way for the control plane protocol stack. Additionally, the terminal device can use the PDCP layer configuration information, RLC layer configuration information, MAC layer configuration information, and PHY layer configuration information carried in the handover command for configuration.

[0200] For the user plane protocol stack, the processing of the SDAP layer is the same. Additionally, the terminal device can release the PDLC, MAC, and PHY layer protocol entities and establish PDCP, RLC, MAC, and PHY protocol layer entities. When releasing the PDLC layer protocol entity, the PDLC SDU (i.e., SDAP PDU) and its corresponding SN / HFN (or, the COUNT value) are retained. At this point, the PDLC SDU can be used as the SDU for the PDCP layer protocol.

[0201] The method embodiments of this application have been described in detail above with reference to Figures 1 to 15. The apparatus embodiments of this application will be described in detail below with reference to Figures 16 to 19. It should be understood that the descriptions of the method embodiments correspond to the descriptions of the apparatus embodiments; therefore, any parts not described in detail can be referred to the preceding method embodiments.

[0202] Figure 16 is a schematic diagram of a terminal device according to an embodiment of this application. The terminal device 1600 shown in Figure 16 includes a processing unit 1610.

[0203] The processing unit 1610 is configured to perform a handover operation, which includes switching between a first access network device and a second access network device, wherein the Radio Access Technology (RAT) corresponding to the first access network device is different from the RAT corresponding to the second access network device.

[0204] In some implementations, the RAT corresponding to the first access network device is the next-generation radio access technology of the RAT corresponding to the second access network device.

[0205] In some implementations, the protocol stack in the terminal device for communicating with the first access network device includes a first SDAP layer and / or a first PDCP layer, wherein the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device; the first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device.

[0206] In some implementations, the protocol stack used for communicating with the first access network device is a user plane protocol stack, which includes the first SDAP layer and the first PDCP layer, and / or the protocol stack used for communicating with the first access network device is a control plane protocol stack, which includes the first PDCP layer.

[0207] In some implementations, the protocol stack used for communicating with the first access network device is a control plane protocol stack, which includes a second RRC layer, and the second RRC layer corresponds to the RAT corresponding to the first access network device.

[0208] In some implementations, the protocol stack used for communicating with the first access network device is a user plane protocol stack, which includes the first SDAP layer.

[0209] In some implementations, the user plane protocol stack includes a second PDCP layer for communicating with the first access network device, wherein the second PDCP layer is the protocol layer of the RAT corresponding to the first access network device.

[0210] In some implementations, the protocol stack in the terminal device used for communicating with the second access network device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device.

[0211] In some implementations, the control plane protocol stack in the terminal device used for communicating with the second access network device includes a first RRC layer, which corresponds to the RAT of the second access network device.

[0212] In some implementations, the terminal device further includes: a first receiving unit, configured to receive a handover command sent by a source access network device, the handover command being used to indicate configuration information for communication between the SDAP layer and / or PDCP layer of the target access network device, the configuration information carrying incremental configuration information based on the configuration information of the SDAP layer and / or PDCP layer of the source access network device.

[0213] In some implementations, the processing unit is configured to obtain configuration information for communicating with the target access network device based on the incremental configuration information and the configuration information of the SDAP layer and / or PDCP layer communicating with the source access network device.

[0214] In some implementations, the processing unit is configured to retain one or more of the following: a PDCP SDU received from the source access network device, an SN context of a PDCP entity associated with the source access network device, and an HFN context of a PDCP entity associated with the source access network device.

[0215] In some implementations, the SN context and the HFN context are used to indicate one or more of the following: the COUNT value of the allocated PDCP SDU, the COUNT value of the next PDCP SDU to be allocated, and the COUNT value of the received PDCP SDU.

[0216] In some implementations, the switching command carries configuration information for one or more protocol layers, wherein the one or more protocol layers are protocol layers of the terminal device other than the SDAP layer and / or PDCP layer that communicate with the target access network device. The processing unit is further configured to: replace the current configuration information of the one or more protocol layers with the configuration information of the one or more protocol layers.

[0217] In some implementations, the source access network device is the first access network device and the target access network device is the second access network device; or the target access network device is the first access network device and the source access network device is the second access network device.

[0218] In some implementations, the protocol stack in the terminal device used for communicating with the first access network device includes a first protocol layer, which is the protocol layer of the RAT corresponding to the first access network device.

[0219] In some implementations, the first protocol layer in the protocol stack of the terminal device is located between the SDAP layer and the MAC layer of the terminal device, wherein the SDAP layer of the terminal device is either the first SDAP layer or the second SDAP layer.

[0220] In some implementations, the length of the SN in the first protocol layer communicating with the source access network device is the same as the length of the SN in the protocol layer communicating with the target access network device, and / or the length of the HFN in the first protocol layer communicating with the source access network device is the same as the length of the HFN in the protocol layer communicating with the target access network device.

[0221] In some implementations, the handover operation includes switching from the second access network device to the first access network device. The processing unit is further configured to replace the configuration information of other protocol layers in the protocol stack used for control plane transmission, excluding the first SDAP layer, with the configuration information carried in the handover command; and / or release the protocol entities of other protocol layers in the protocol stack used for user plane transmission, excluding the first SDAP layer, and establish the protocol entities of the other protocol layers used for communication with the first access network device.

[0222] In some implementations, the other protocol layers in the protocol stack for control plane transmission include one or more of the first protocol layer, MAC layer, and PHY layer; or the protocol entities of the other protocol layers in the protocol stack for user plane transmission include one or more of the following: protocol entity of PDCP layer, protocol entity of RLC layer, protocol entity of MAC layer, and protocol entity of PHY layer.

[0223] In some implementations, the handover operation includes switching from the first access network device to the second access network device. The processing unit is further configured to replace the configuration information of other protocol layers in the protocol stack used for control plane transmission, excluding the first SDAP layer, with the configuration information carried in the handover command; and / or release the protocol entities of other protocol layers in the protocol stack used for user plane transmission, excluding the first SDAP layer, and establish the protocol entities of the other protocol layers used for communication with the second access network device.

[0224] In some implementations, the other protocol layers in the protocol stack for control plane transmission include one or more of the following: PDCP layer, RLC layer, MAC layer, and PHY layer; or the protocol entities of the other protocol layers in the protocol stack for user plane transmission include one or more of the following: protocol entity of PDCP layer, protocol entity of RLC layer, protocol entity of MAC layer, and protocol entity of PHY layer.

[0225] In some implementations, the processing unit is further configured to retain one or more of the following: a first protocol layer SDU received from the source access network device, an SN context corresponding to a first protocol layer entity associated with the source access network device, and an HFN context corresponding to the first protocol layer entity.

[0226] In some implementations, the SN context and the HFN context are used to indicate one or more of the following: the COUNT value of the first protocol layer SDU that has been assigned, the COUNT value of the next first protocol layer SDU to be assigned, the COUNT value of the first protocol layer SDU that has been received, the COUNT value of the next SDU that is expected to be received, the COUNT value of the first SDU that has not been delivered to the higher protocol layer, and the COUNT value of the SDU associated with starting the reordering timer.

[0227] Figure 17 is a schematic diagram of an access network device according to an embodiment of this application. The access network device 1700 shown in Figure 17 is a source access network device, and the access network device 1700 includes: a transmitting unit 1710.

[0228] The sending unit 1710 is used to send a handover command to the terminal device. The handover command is used to instruct the terminal device to switch from the source access network device to the target access network device. The radio access technology (RAT) corresponding to the source access network device is different from the RAT corresponding to the target access network device.

[0229] In some implementations, the source access network device is a first access network device and the target access network device is a second access network device, or the source access network device is a second access network device and the target access network device is a first access network device, wherein the RAT corresponding to the first access network device is the next-generation radio access technology of the RAT corresponding to the second access network device.

[0230] In some implementations, the protocol stack in the first access network device for communicating with the terminal device includes a first SDAP layer and / or a first PDCP layer, wherein the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device; the first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device.

[0231] In some implementations, the protocol stack used for communicating with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer and the first PDCP layer, and / or the protocol stack used for communicating with the terminal device in the first access network device is a control plane protocol stack, which includes the first PDCP layer.

[0232] In some implementations, the protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes a second RRC layer, and the second RRC layer corresponds to the RAT of the first access network device.

[0233] In some implementations, the protocol stack used for communicating with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer.

[0234] In some implementations, the protocol stack in the first access network device used for communication with the terminal device includes a second PDCP layer, which is the protocol layer of the RAT corresponding to the first access network device.

[0235] In some implementations, the protocol stack in the second access network device used for communicating with the terminal device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device.

[0236] In some implementations, the control plane protocol stack in the second access network device for communicating with the terminal device includes a first RRC layer, which corresponds to the RAT of the second access network device.

[0237] In some implementations, the access network device further includes: a first receiving unit, configured to receive a handover request confirmation message sent by the target access network device, wherein the handover command carried in the handover request confirmation message is used to indicate the configuration information of the SDAP layer and / or PDCP layer communication of the target access network device, wherein the configuration information carries incremental configuration information based on the configuration information of the SDAP layer and / or PDCP layer corresponding to the source access network device, and the SDAP layer and / or PDCP layer corresponding to the source access network device is a protocol layer in the source access network device used for communication with the terminal device.

[0238] In some implementations, the access network device further includes: a first sending unit, configured to send a handover request to the target access network device, the handover request carrying configuration information of the SDAP layer and / or PDCP layer of the source access network device.

[0239] In some implementations, the access network device further includes: a second sending unit, configured to send first information to the target access network device, the first information carrying one or more of the following: a PDCP SDU to be sent; a PDCP SDU that has been sent but not yet acknowledged; a COUNT value associated with a PDCP SDU that has been sent but not yet acknowledged; a COUNT value of the first PDCP SDU to be allocated; a PDCP SDU that has been received; and status information of a PDCP SDU to be received.

[0240] In some implementations, the switching command carries configuration information for one or more protocol layers, which are protocol layers in the target access network device's protocol stack used for communicating with the terminal device, excluding the SDAP layer and / or PDCP layer used for communicating with the terminal device.

[0241] In some implementations, the protocol stack in the first access network device used for communicating with the terminal device includes a first protocol layer, which is the protocol layer of the RAT corresponding to the first access network device.

[0242] In some implementations, in the protocol stack of the first access network device used for communication with the terminal device, the first protocol layer is located between the SDAP layer and the MAC layer of the first access network device, and the SDAP layer of the first access network device includes a first SDAP layer or a second SDAP layer.

[0243] In some implementations, the length of the SN in the first protocol layer of the source access network device is the same as the length of the SN in the protocol layer of the target access network device, and / or the length of the HFN in the first protocol layer of the source access network device is the same as the length of the HFN in the protocol layer of the target access network device.

[0244] In some implementations, the sending unit is further configured to: send second information to the target access network device, the second information carrying the SDU of the first protocol layer and / or the COUNT value corresponding to the SDU of the first protocol layer.

[0245] Figure 18 is a schematic diagram of an access network device according to an embodiment of this application. The access network device shown in Figure 18 is the target access network device, and the access network device 1800 includes: a transmitting unit 1810.

[0246] The sending unit 1810 is used to send a handover request confirmation message to the source access network device. The handover command carried in the handover request confirmation message is used to instruct the terminal device to hand over from the source access network device to the target access network device. The radio access technology (RAT) corresponding to the source access network device is different from the RAT corresponding to the target access network device.

[0247] In some implementations, the source access network device is a first access network device and the target access network device is a second access network device, or the source access network device is a second access network device and the target access network device is a first access network device, wherein the RAT corresponding to the first access network device is the next-generation radio access technology of the RAT corresponding to the second access network device.

[0248] In some implementations, the protocol stack in the first access network device for communicating with the terminal device includes a first SDAP layer and / or a first PDCP layer, wherein the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device; the first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device.

[0249] In some implementations, the protocol stack used for communicating with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer and the first PDCP layer, and / or the protocol stack used for communicating with the terminal device in the first access network device is a control plane protocol stack, which includes the first PDCP layer.

[0250] In some implementations, the protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes a second RRC layer, and the second RRC layer corresponds to the RAT of the first access network device.

[0251] In some implementations, the protocol stack used for communicating with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer.

[0252] In some implementations, the protocol stack in the first access network device used for communication with the terminal device includes a second PDCP layer, which is the protocol layer of the RAT corresponding to the first access network device.

[0253] In some implementations, the protocol stack in the second access network device used for communicating with the terminal device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device.

[0254] In some implementations, the control plane protocol stack in the second access network device for communicating with the terminal device includes a first RRC layer, which corresponds to the RAT of the second access network device.

[0255] In some implementations, the switching command is used to indicate the configuration information of the SDAP layer and / or PDCP layer communication corresponding to the target access network device, wherein the SDAP layer and / or PDCP layer corresponding to the source access network device is the protocol layer in the source access network device used to communicate with the terminal device.

[0256] In some implementations, the access network device further includes: a first receiving unit, configured to receive a handover request sent by the source access network device, the handover request carrying configuration information of the SDAP layer and / or PDCP layer in the source access network device for communicating with the terminal device.

[0257] In some implementations, the access network device further includes: a second receiving unit, configured to receive first information sent by the source access network device, the first information carrying one or more of the following: a PDCP SDU to be sent; a PDCP SDU that has been sent but not yet acknowledged; a COUNT value associated with a PDCP SDU that has been sent but not yet acknowledged; a PDCP SDU that has been received; and status information of a PDCP SDU to be received.

[0258] In some implementations, the switching command carries configuration information for one or more protocol layers, which are protocol layers in the target access network device's protocol stack used for communicating with the terminal device, excluding the SDAP layer and / or PDCP layer used for communicating with the terminal device.

[0259] In some implementations, the protocol stack in the first access network device used for communicating with the terminal device includes a first protocol layer, which is the protocol layer of the RAT corresponding to the first access network device.

[0260] In some implementations, in the protocol stack of the first access network device used for communication with the terminal device, the first protocol layer is located between the SDAP layer and the MAC layer of the first access network device, and the SDAP layer of the first access network device includes a first SDAP layer or a second SDAP layer.

[0261] In some implementations, the length of the SN in the first protocol layer of the source access network device is the same as the length of the SN in the protocol layer of the target access network device, and / or the length of the HFN in the first protocol layer of the source access network device is the same as the length of the HFN in the protocol layer of the target access network device.

[0262] In some implementations, the receiving unit is further configured to: receive second information sent by the source access network device, the second information carrying the SDU of the first protocol layer and / or the COUNT value corresponding to the SDU of the first protocol layer.

[0263] Figure 19 is a schematic structural diagram of a communication device according to an embodiment of this application. The dashed lines in Figure 19 indicate that the unit or module is optional. This device 1900 can be used to implement the methods described in the above method embodiments. Device 1900 can be a chip, a terminal device, or a network device.

[0264] Apparatus 1900 may include one or more processors 1910. The processor 1910 may support apparatus 1900 in implementing the methods described in the preceding method embodiments. The processor 1910 may be a general-purpose processor or a special-purpose processor. For example, the processor may be a central processing unit (CPU). Alternatively, the processor may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0265] The apparatus 1900 may further include one or more memories 1920. The memories 1920 store a program that can be executed by the processor 1910, causing the processor 1910 to perform the methods described in the preceding method embodiments. The memories 1920 may be independent of the processor 1910 or integrated within the processor 1910.

[0266] The device 1900 may also include a transceiver 1930. The processor 1910 can communicate with other devices or chips via the transceiver 1930. For example, the processor 1910 can send and receive data with other devices or chips via the transceiver 1930.

[0267] This application also provides a computer-readable storage medium for storing a program. This computer-readable storage medium can be applied to a terminal or network device provided in this application, and the program causes a computer to execute the methods performed by the terminal or network device in various embodiments of this application.

[0268] This application also provides a computer program product. The computer program product includes a program. The computer program product can be applied to a terminal or network device provided in this application embodiment, and the program causes a computer to execute the methods performed by the terminal or network device in various embodiments of this application.

[0269] This application also provides a computer program. This computer program can be applied to the terminal or network device provided in this application, and the computer program causes the computer to execute the methods performed by the terminal or network device in various embodiments of this application.

[0270] It should be understood that the terms "system" and "network" in this application can be used interchangeably. Furthermore, the terminology used in this application is only for explaining specific embodiments of the application and is not intended to limit the application. The terms "first," "second," "third," and "fourth," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. In addition, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0271] In the embodiments of this application, the term "instruction" can be a direct instruction, an indirect instruction, or an indication of a relationship. For example, A instructing B can mean that A directly instructs B, such as B being able to obtain information through A; it can also mean that A indirectly instructs B, such as A instructing C, so B can obtain information through C; or it can mean that there is a relationship between A and B.

[0272] In the embodiments of this application, "B corresponding to A" means that B is associated with A, and B can be determined based on A. However, it should also be understood that determining B based on A does not mean that B is determined solely based on A; B can also be determined based on A and / or other information.

[0273] In the embodiments of this application, the term "correspondence" can indicate a direct or indirect correspondence between two things, or an association between two things, or a relationship such as instruction and being instructed, configuration and being configured.

[0274] In this application embodiment, "predefined" or "preconfigured" can be implemented by pre-storing corresponding codes, tables, or other means that can be used to indicate relevant information in the device (e.g., including terminal devices and network devices). This application does not limit the specific implementation method. For example, predefined can refer to what is defined in the protocol.

[0275] In this application embodiment, the "protocol" may refer to a standard protocol in the field of communication, such as the LTE protocol, the NR protocol, and related protocols applied to future communication systems. This application does not limit this.

[0276] In the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0277] In the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0278] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0279] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0280] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0281] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially 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, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can read or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., digital video discs, DVDs) or semiconductor media (e.g., solid-state disks, SSDs), etc.

[0282] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for wireless communication, characterized in that, include: The terminal device performs a handover operation, which includes switching between a first access network device and a second access network device, wherein the Radio Access Technology (RAT) corresponding to the first access network device is different from the RAT corresponding to the second access network device.

2. The method as described in claim 1, characterized in that, The RAT corresponding to the first access network device is the next-generation wireless access technology of the RAT corresponding to the second access network device.

3. The method as described in claim 1 or 2, characterized in that, The protocol stack in the terminal device used for communication with the first access network device includes a first SDAP layer and / or a first PDCP layer. Wherein, the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device; The first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device.

4. The method as described in claim 3, characterized in that, The protocol stack used for communicating with the first access network device is a user plane protocol stack, which includes the first SDAP layer and the first PDCP layer, and / or The protocol stack used for communicating with the first access network device is a control plane protocol stack, which includes the first PDCP layer.

5. The method as described in claim 4, characterized in that, The protocol stack used for communicating with the first access network device is a control plane protocol stack, which includes a second RRC layer, and the second RRC layer corresponds to the RAT of the first access network device.

6. The method as described in claim 3, characterized in that, The protocol stack used for communicating with the first access network device is a user plane protocol stack, which includes the first SDAP layer.

7. The method as described in claim 6, characterized in that, The user plane protocol stack includes a second PDCP layer for communicating with the first access network device, and the second PDCP layer is the protocol layer of the RAT corresponding to the first access network device.

8. The method as described in claim 1 or 2, characterized in that, The protocol stack in the terminal device used for communication with the second access network device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device.

9. The method as described in claim 8, characterized in that, The control plane protocol stack in the terminal device used for communication with the second access network device includes a first RRC layer, which corresponds to the RAT of the second access network device.

10. The method according to any one of claims 3-9, characterized in that, The method further includes: The terminal device receives a handover command sent by the source access network device. The handover command is used to indicate the configuration information of the SDAP layer and / or PDCP layer communicating with the target access network device. The configuration information carries incremental configuration information based on the configuration information of the SDAP layer and / or PDCP layer communicating with the source access network device.

11. The method as described in claim 10, characterized in that, The method further includes: The terminal device obtains configuration information for communicating with the target access network device based on the incremental configuration information and the configuration information of the SDAP layer and / or PDCP layer for communicating with the source access network device.

12. The method as described in claim 10 or 11, characterized in that, The method further includes: The terminal device retains one or more of the following: a PDCP SDU received from the source access network device, an SN context of a PDCP entity associated with the source access network device, and an HFN context of a PDCP entity associated with the source access network device.

13. The method as described in claim 12, characterized in that, The SN context and the HFN context are used to indicate one or more of the following: the COUNT value of the assigned PDCP SDU, the COUNT value of the next PDCP SDU to be assigned, and the COUNT value of the received PDCP SDU.

14. The method according to any one of claims 10-13, characterized in that, The handover command carries configuration information for one or more protocol layers, wherein the one or more protocol layers are protocol layers of the terminal device other than the SDAP layer and / or PDCP layer that communicate with the target access network device. The method further includes: The terminal device replaces the current configuration information of the one or more protocol layers with the configuration information of the one or more protocol layers.

15. The method according to any one of claims 10-14, characterized in that, The source access network device is the first access network device, and the target access network device is the second access network device; or The target access network device is the first access network device, and the source access network device is the second access network device.

16. The method according to any one of claims 3, 7-13, characterized in that, The protocol stack in the terminal device used for communicating with the first access network device includes a first protocol layer, which is the protocol layer of the RAT corresponding to the first access network device.

17. The method as described in claim 16, characterized in that, In the protocol stack of the terminal device, the first protocol layer is located between the SDAP layer and the MAC layer of the terminal device, wherein the SDAP layer of the terminal device is either the first SDAP layer or the second SDAP layer.

18. The method as described in claim 16 or 17, characterized in that, The length of the SN in the first protocol layer communicating with the source access network device is the same as the length of the SN in the protocol layer communicating with the target access network device, and / or The length of the HFN in the first protocol layer communicating with the source access network device is the same as the length of the HFN in the protocol layer communicating with the target access network device.

19. The method according to any one of claims 16-18, characterized in that, The handover operation includes switching from the second access network device to the first access network device, and the method further includes: The terminal device replaces the configuration information of other protocol layers in the protocol stack used for control plane transmission, excluding the first SDAP layer, with the configuration information carried in the handover command; and / or The terminal device releases the protocol entities of the other protocol layers in the protocol stack used for user plane transmission, excluding the first SDAP layer, and establishes the protocol entities of the other protocol layers used for communication with the first access network device.

20. The method as described in claim 19, characterized in that, The other protocol layers in the protocol stack used for control plane transmission include one or more of the following: a first protocol layer, a MAC layer, and a PHY layer; or The protocol entities of other protocol layers in the protocol stack used for user plane transmission include one or more of the following: protocol entities of the PDCP layer, protocol entities of the RLC layer, protocol entities of the MAC layer, and protocol entities of the PHY layer.

21. The method according to any one of claims 16-18, characterized in that, The handover operation includes switching from the first access network device to the second access network device, and the method further includes: The terminal device replaces the configuration information of other protocol layers in the protocol stack used for control plane transmission, excluding the first SDAP layer, with the configuration information carried in the handover command; and / or The terminal device releases the protocol entities of the other protocol layers in the protocol stack used for user plane transmission, excluding the first SDAP layer, and establishes the protocol entities of the other protocol layers used for communication with the second access network device.

22. The method as described in claim 21, characterized in that, The other protocol layers in the protocol stack used for control plane transmission include one or more of the following: PDCP layer, RLC layer, MAC layer, and PHY layer; or The protocol entities of other protocol layers in the protocol stack used for user plane transmission include one or more of the following: protocol entities of the PDCP layer, protocol entities of the RLC layer, protocol entities of the MAC layer, and protocol entities of the PHY layer.

23. The method as described in claim 21 or 22, characterized in that, The method further includes: The terminal device retains one or more of the following: a first protocol layer SDU received from the source access network device, an SN context of a first protocol layer entity associated with the source access network device, and an HFN context of the first protocol layer entity.

24. The method as described in claim 23, characterized in that, The SN context and the HFN context are used to indicate one or more of the following: the COUNT value of the first protocol layer SDU that has been assigned, the COUNT value of the next first protocol layer SDU to be assigned, the COUNT value of the first protocol layer SDU that has been received, the COUNT value of the next SDU that is expected to be received, the COUNT value of the first SDU that has not been delivered to the higher protocol layer, and the COUNT value of the SDU associated with starting the reordering timer.

25. A method for wireless communication, characterized in that, include: The source access network device sends a handover command to the terminal device. The handover command is used to instruct the terminal device to switch from the source access network device to the target access network device. The radio access technology (RAT) corresponding to the source access network device is different from the RAT corresponding to the target access network device.

26. The method as described in claim 25, characterized in that, The source access network device is a first access network device, and the target access network device is a second access network device, or The source access network device is a second access network device, and the target access network device is a first access network device. Wherein, the RAT corresponding to the first access network device is the next-generation wireless access technology of the RAT corresponding to the second access network device.

27. The method as described in claim 26, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a first SDAP layer and / or a first PDCP layer. Wherein, the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device; The first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device.

28. The method as described in claim 27, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer and the first PDCP layer, and / or The protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes the first PDCP layer.

29. The method as described in claim 28, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes a second RRC layer, and the second RRC layer corresponds to the RAT of the first access network device.

30. The method as described in claim 27, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer.

31. The method as described in claim 30, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a second PDCP layer, which is the protocol layer of the RAT corresponding to the first access network device.

32. The method as described in claim 25 or 26, characterized in that, The protocol stack in the second access network device used for communication with the terminal device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device.

33. The method as described in claim 32, characterized in that, The control plane protocol stack in the second access network device for communicating with the terminal device includes a first RRC layer, which corresponds to the RAT of the second access network device.

34. The method according to any one of claims 25-33, characterized in that, The method further includes: The source access network device receives a handover request confirmation message sent by the target access network device. The handover command carried in the handover request confirmation message is used to indicate the configuration information of the SDAP layer and / or PDCP layer in the target access network device for communicating with the terminal device. The configuration information carries incremental configuration information based on the configuration information of the SDAP layer and / or PDCP layer corresponding to the source access network device. The SDAP layer and / or PDCP layer corresponding to the source access network device are the protocol layers in the source access network device used for communication with the terminal device.

35. The method according to any one of claims 25-34, characterized in that, The method further includes: The source access network device sends a handover request to the target access network device, the handover request carrying the configuration information of the SDAP layer and / or PDCP layer of the source access network device.

36. The method as described in claim 34 or 35, characterized in that, The method further includes: The source access network device sends first information to the target access network device, the first information carrying one or more of the following: PDCP SDU to be sent; PDCP SDU sent but not yet acknowledged; The COUNT value associated with a PDCP SDU that has been sent but not yet acknowledged; The COUNT value of the first PDCP SDU to be assigned; Received PDCP SDU; Status information of the PDCP SDU to be received.

37. The method according to any one of claims 33-36, characterized in that, The switching command carries configuration information for one or more protocol layers, which are protocol layers in the target access network device used to communicate with the terminal device, excluding the SDAP layer and / or PDCP layer used to communicate with the terminal device.

38. The method according to any one of claims 28, 31-36, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a first protocol layer, which is the protocol layer of the RAT corresponding to the first access network device.

39. The method as described in claim 38, characterized in that, In the protocol stack used for communication with the terminal device in the first access network device, the first protocol layer is located between the SDAP layer and the MAC layer of the first access network device, and the SDAP layer of the first access network device includes a first SDAP layer or a second SDAP layer.

40. The method as described in claim 38 or 39, characterized in that, The length of the SN in the first protocol layer of the source access network device is the same as the length of the SN in the protocol layer of the target access network device, and / or The length of the HFN in the first protocol layer of the source access network device is the same as the length of the HFN in the protocol layer of the target access network device.

41. The method according to any one of claims 38-40, characterized in that, The method further includes: The source access network device sends second information to the target access network device, the second information carrying the SDU of the first protocol layer and / or the COUNT value corresponding to the SDU of the first protocol layer.

42. A method for wireless communication, characterized in that, include: The target access network device sends a handover request confirmation message to the source access network device. The handover command carried in the handover request confirmation message is used to instruct the terminal device to hand over from the source access network device to the target access network device. The radio access technology (RAT) corresponding to the source access network device is different from the RAT corresponding to the target access network device.

43. The method as described in claim 42, characterized in that, The source access network device is a first access network device, and the target access network device is a second access network device, or The source access network device is a second access network device, and the target access network device is a first access network device. Wherein, the RAT corresponding to the first access network device is the next-generation wireless access technology of the RAT corresponding to the second access network device.

44. The method as described in claim 43, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a first SDAP layer and / or a first PDCP layer. Wherein, the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device; The first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device.

45. The method as described in claim 44, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer and the first PDCP layer, and / or The protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes the first PDCP layer.

46. ​​The method as described in claim 45, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes a second RRC layer, and the second RRC layer corresponds to the RAT of the first access network device.

47. The method as described in claim 46, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer.

48. The method as described in claim 47, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a second PDCP layer, which is the protocol layer of the RAT corresponding to the first access network device.

49. The method as described in claim 42 or 43, characterized in that, The protocol stack in the second access network device used for communication with the terminal device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device.

50. The method as described in claim 49, characterized in that, The control plane protocol stack in the second access network device for communicating with the terminal device includes a first RRC layer, which corresponds to the RAT of the second access network device.

51. The method according to any one of claims 42-50, characterized in that, The switching command is used to indicate the configuration information of the SDAP layer and / or PDCP layer in the target access network device for communicating with the terminal device. The configuration information carries incremental configuration information based on the configuration information of the SDAP layer and / or PDCP layer corresponding to the source access network device. The SDAP layer and / or PDCP layer corresponding to the source access network device are the protocol layers in the source access network device used for communication with the terminal device.

52. The method according to any one of claims 42-51, characterized in that, The method further includes: The target access network device receives a handover request sent by the source access network device. The handover request carries configuration information of the SDAP layer and / or PDCP layer in the source access network device used for communication with the terminal device.

53. The method as described in claim 51 or 52, characterized in that, The method further includes: The target access network device receives first information sent by the source access network device, the first information carrying one or more of the following: PDCP SDU to be sent; PDCP SDU sent but not yet acknowledged; The COUNT value associated with a PDCP SDU that has been sent but not yet acknowledged; Received PDCP SDU; Status information of the PDCP SDU to be received.

54. The method according to any one of claims 50-53, characterized in that, The switching command carries configuration information for one or more protocol layers, which are protocol layers in the target access network device used to communicate with the terminal device, excluding the SDAP layer and / or PDCP layer used to communicate with the terminal device.

55. The method according to any one of claims 45, 48-53, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a first protocol layer, which is the protocol layer of the RAT corresponding to the first access network device.

56. The method as described in claim 55, characterized in that, In the protocol stack used for communication with the terminal device in the first access network device, the first protocol layer is located between the SDAP layer and the MAC layer of the first access network device, and the SDAP layer of the first access network device includes a first SDAP layer or a second SDAP layer.

57. The method as described in claim 55 or 56, characterized in that, The length of the SN in the first protocol layer of the source access network device is the same as the length of the SN in the protocol layer of the target access network device, and / or The length of the HFN in the first protocol layer of the source access network device is the same as the length of the HFN in the protocol layer of the target access network device.

58. The method according to any one of claims 55-57, characterized in that, The method further includes: The target access network device receives second information sent by the source access network device, the second information carrying the SDU of the first protocol layer and / or the COUNT value corresponding to the SDU of the first protocol layer.

59. A terminal device, characterized in that, include: A processing unit is configured to perform a handover operation, which includes switching between a first access network device and a second access network device, wherein the Radio Access Technology (RAT) corresponding to the first access network device is different from the RAT corresponding to the second access network device.

60. The terminal device as described in claim 59, characterized in that, The RAT corresponding to the first access network device is the next-generation wireless access technology of the RAT corresponding to the second access network device.

61. The terminal device as described in claim 59 or 60, characterized in that, The protocol stack in the terminal device used for communication with the first access network device includes a first SDAP layer and / or a first PDCP layer. Wherein, the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device; The first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device.

62. The terminal device as described in claim 61, characterized in that, The protocol stack used for communicating with the first access network device is a user plane protocol stack, which includes the first SDAP layer and the first PDCP layer, and / or The protocol stack used for communicating with the first access network device is a control plane protocol stack, which includes the first PDCP layer.

63. The terminal device as described in claim 62, characterized in that, The protocol stack used for communicating with the first access network device is a control plane protocol stack, which includes a second RRC layer, and the second RRC layer corresponds to the RAT of the first access network device.

64. The terminal device as described in claim 61, characterized in that, The protocol stack used for communicating with the first access network device is a user plane protocol stack, which includes the first SDAP layer.

65. The terminal device as described in claim 64, characterized in that, The user plane protocol stack includes a second PDCP layer for communicating with the first access network device, and the second PDCP layer is the protocol layer of the RAT corresponding to the first access network device.

66. The terminal device as described in claim 59 or 60, characterized in that, The protocol stack in the terminal device used for communication with the second access network device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device.

67. The terminal device as described in claim 66, characterized in that, The control plane protocol stack in the terminal device used for communication with the second access network device includes a first RRC layer, which corresponds to the RAT of the second access network device.

68. The terminal device as described in any one of claims 61-67, characterized in that, The terminal device also includes: The first receiving unit is configured to receive a handover command sent by the source access network device. The handover command is used to indicate the configuration information of the SDAP layer and / or PDCP layer communicating with the target access network device. The configuration information carries incremental configuration information based on the configuration information of the SDAP layer and / or PDCP layer communicating with the source access network device.

69. The terminal device as described in claim 68, characterized in that, The processing unit is used for: Based on the incremental configuration information and the configuration information of the SDAP layer and / or PDCP layer for communicating with the source access network device, configuration information of the SDAP layer and / or PDCP layer for communicating with the target access network device is obtained.

70. The terminal device as described in claim 68 or 69, characterized in that, The processing unit is used for: One or more of the following are retained: the PDCP SDU received from the source access network device, the SN context of the PDCP entity associated with the source access network device, and the HFN context of the PDCP entity associated with the source access network device.

71. The terminal device as described in claim 70, characterized in that, The SN context and the HFN context include one or more of the following: the COUNT value of the assigned PDCP SDU, the COUNT value of the next PDCP SDU to be assigned, the COUNT value of the received PDCP SDU, and the HFN context.

72. The terminal device as described in any one of claims 68-71, characterized in that, The handover command carries configuration information for one or more protocol layers, wherein the one or more protocol layers are protocol layers of the terminal device other than the SDAP layer and / or PDCP layer that communicate with the target access network device. The processing unit is further configured to: Replace the current configuration information of the one or more protocol layers with the configuration information of the one or more protocol layers.

73. The terminal device as described in any one of claims 68-72, characterized in that, The source access network device is the first access network device, and the target access network device is the second access network device; or The target access network device is the first access network device, and the source access network device is the second access network device.

74. The terminal device as described in any one of claims 61, 65-71, characterized in that, The protocol stack in the terminal device used for communicating with the first access network device includes a first protocol layer, which is the protocol layer of the RAT corresponding to the first access network device.

75. The terminal device as described in claim 74, characterized in that, In the protocol stack of the terminal device, the first protocol layer is located between the SDAP layer and the MAC layer of the terminal device, wherein the SDAP layer of the terminal device is either the first SDAP layer or the second SDAP layer.

76. The terminal device as described in claim 74 or 75, characterized in that, The length of the SN in the first protocol layer communicating with the source access network device is the same as the length of the SN in the protocol layer communicating with the target access network device, and / or The length of the HFN in the first protocol layer communicating with the source access network device is the same as the length of the HFN in the protocol layer communicating with the target access network device.

77. The terminal device as described in any one of claims 74-76, characterized in that, The handover operation includes switching from the second access network device to the first access network device, and the processing unit is further configured to: Replace the configuration information of all protocol layers in the protocol stack used for control plane transmission, except for the first SDAP layer, with the configuration information carried in the handover command; and / or Release the protocol entities of the protocol layers other than the first SDAP layer in the protocol stack used for user plane transmission, and establish the protocol entities of the other protocol layers used for communication with the first access network device.

78. The terminal device as described in claim 77, characterized in that, The other protocol layers in the protocol stack used for control plane transmission include one or more of the following: a first protocol layer, a MAC layer, and a PHY layer; or The protocol entities of other protocol layers in the protocol stack used for user plane transmission include one or more of the following: protocol entities of the PDCP layer, protocol entities of the RLC layer, protocol entities of the MAC layer, and protocol entities of the PHY layer.

79. The terminal device as described in any one of claims 74-76, characterized in that, The handover operation includes switching from the first access network device to the second access network device, and the processing unit is further configured to: Replace the configuration information of all protocol layers in the protocol stack used for control plane transmission, except for the first SDAP layer, with the configuration information carried in the handover command; and / or Release the protocol entities of the protocol layers other than the first SDAP layer in the protocol stack used for user plane transmission, and establish the protocol entities of the other protocol layers used for communication with the second access network device.

80. The terminal device as described in claim 79, characterized in that, The other protocol layers in the protocol stack used for control plane transmission include one or more of the following: PDCP layer, RLC layer, MAC layer, and PHY layer; or The protocol entities of other protocol layers in the protocol stack used for user plane transmission include one or more of the following: protocol entities of the PDCP layer, protocol entities of the RLC layer, protocol entities of the MAC layer, and protocol entities of the PHY layer.

81. The terminal device as described in claim 79 or 80, characterized in that, The processing unit is further configured to: One or more of the following may be retained: a first protocol layer SDU received from the source access network device, an SN context corresponding to a first protocol layer entity associated with the source access network device, and an HFN context corresponding to the first protocol layer entity.

82. The terminal device as described in claim 81, characterized in that, The SN context and the HFN context are used to indicate one or more of the following: the COUNT value of the first protocol layer SDU that has been assigned, the COUNT value of the next first protocol layer SDU to be assigned, the COUNT value of the first protocol layer SDU that has been received, the COUNT value of the next SDU that is expected to be received, the COUNT value of the first SDU that has not been delivered to the higher protocol layer, the COUNT value of the SDU associated with starting the reordering timer, and the HFN context.

83. An access network device, characterized in that, The access network device is a source access network device, including: The sending unit is used to send a handover command to the terminal device. The handover command is used to instruct the terminal device to switch from the source access network device to the target access network device. The radio access technology (RAT) corresponding to the source access network device is different from the RAT corresponding to the target access network device.

84. The access network device as described in claim 83, characterized in that, The source access network device is a first access network device, and the target access network device is a second access network device, or The source access network device is a second access network device, and the target access network device is a first access network device. Wherein, the RAT corresponding to the first access network device is the next-generation wireless access technology of the RAT corresponding to the second access network device.

85. The access network device as described in claim 84, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a first SDAP layer and / or a first PDCP layer. Wherein, the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device; The first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device.

86. The access network device as described in claim 85, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer and the first PDCP layer, and / or The protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes the first PDCP layer.

87. The access network device as described in claim 86, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes a second RRC layer, and the second RRC layer corresponds to the RAT of the first access network device.

88. The access network device as described in claim 85, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer.

89. The access network device as described in claim 88, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a second PDCP layer, which is the protocol layer of the RAT corresponding to the first access network device.

90. The access network device as described in claim 83 or 84, characterized in that, The protocol stack in the second access network device used for communication with the terminal device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device.

91. The access network device as described in claim 90, characterized in that, The control plane protocol stack in the second access network device for communicating with the terminal device includes a first RRC layer, which corresponds to the RAT of the second access network device.

92. The access network equipment as described in any one of claims 83-91, characterized in that, The access network equipment also includes: The first receiving unit is configured to receive a handover request confirmation message sent by the target access network device. The handover command carried in the handover request confirmation message is used to indicate the configuration information of the SDAP layer and / or PDCP layer communication in the target access network device for communicating with the terminal device. The configuration information carries incremental configuration information based on the configuration information of the SDAP layer and / or PDCP layer corresponding to the source access network device. The SDAP layer and / or PDCP layer corresponding to the source access network device are the protocol layers in the source access network device used for communication with the terminal device.

93. The access network equipment as described in any one of claims 83-92, characterized in that, The access network equipment also includes: The first sending unit is used to send a handover request to the target access network device, the handover request carrying configuration information of the SDAP layer and / or PDCP layer of the source access network device.

94. The access network equipment as described in claim 92 or 93, characterized in that, The access network equipment also includes: The second sending unit is configured to send first information to the target access network device, wherein the first information carries one or more of the following: PDCP SDU to be sent; PDCP SDU sent but not yet acknowledged; The COUNT value associated with a PDCP SDU that has been sent but not yet acknowledged; The COUNT value of the first PDCP SDU to be assigned; Received PDCP SDU; Status information of the PDCP SDU to be received.

95. The access network equipment as described in any one of claims 91-94, characterized in that, The switching command carries configuration information for one or more protocol layers, which are protocol layers in the target access network device used to communicate with the terminal device, excluding the SDAP layer and / or PDCP layer used to communicate with the terminal device.

96. The access network equipment as described in any one of claims 86, 89-94, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a first protocol layer, which is the protocol layer of the RAT corresponding to the first access network device.

97. The access network device as described in claim 96, characterized in that, In the protocol stack used for communication with the terminal device in the first access network device, the first protocol layer is located between the SDAP layer and the MAC layer of the first access network device, and the SDAP layer of the first access network device includes a first SDAP layer or a second SDAP layer.

98. The access network equipment as described in claim 96 or 97, characterized in that, The length of the SN in the first protocol layer of the source access network device is the same as the length of the SN in the protocol layer of the target access network device, and / or The length of the HFN in the first protocol layer of the source access network device is the same as the length of the HFN in the protocol layer of the target access network device.

99. The access network equipment as described in any one of claims 96-98, characterized in that, The transmitting unit is further configured to: Send second information to the target access network device, the second information carrying the SDU of the first protocol layer and / or the COUNT value corresponding to the SDU of the first protocol layer.

100. An access network device, characterized in that, The access network device is the target access network device, including: The sending unit is used to send a handover request confirmation message to the source access network device. The handover command carried in the handover request confirmation message is used to instruct the terminal device to hand over from the source access network device to the target access network device. The Radio Access Technology (RAT) corresponding to the source access network device is different from the RAT corresponding to the target access network device.

101. The access network device as described in claim 100, characterized in that, The source access network device is a first access network device, and the target access network device is a second access network device, or The source access network device is a second access network device, and the target access network device is a first access network device. Wherein, the RAT corresponding to the first access network device is the next-generation wireless access technology of the RAT corresponding to the second access network device.

102. The access network device as described in claim 101, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a first SDAP layer and / or a first PDCP layer. Wherein, the first SDAP layer is the protocol layer of the RAT corresponding to the second access network device, and the first SDAP layer supports processing the information format corresponding to the first access network device; The first PDCP layer is the protocol layer of the RAT corresponding to the second access network device, and the first PDCP layer is used to process the information format corresponding to the first access network device.

103. The access network device as described in claim 102, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer and the first PDCP layer, and / or The protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes the first PDCP layer.

104. The access network device as described in claim 103, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a control plane protocol stack, which includes a second RRC layer, and the second RRC layer corresponds to the RAT of the first access network device.

105. The access network device as described in claim 102, characterized in that, The protocol stack used for communication with the terminal device in the first access network device is a user plane protocol stack, which includes the first SDAP layer.

106. The access network device as described in claim 105, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a second PDCP layer, which is the protocol layer of the RAT corresponding to the first access network device.

107. The access network device as described in claim 100 or 101, characterized in that, The protocol stack in the second access network device used for communication with the terminal device includes a second SDAP layer, which is the protocol layer of the RAT corresponding to the first access network device.

108. The access network device as described in claim 107, characterized in that, The control plane protocol stack in the second access network device for communicating with the terminal device includes a first RRC layer, which corresponds to the RAT of the second access network device.

109. The access network device as described in any one of claims 100-108, characterized in that, The switching command is used to indicate the configuration information of the SDAP layer and / or PDCP layer in the target access network device for communicating with the terminal device. The configuration information carries incremental configuration information based on the configuration information of the SDAP layer and / or PDCP layer corresponding to the source access network device. The SDAP layer and / or PDCP layer corresponding to the source access network device are the protocol layers in the source access network device used for communication with the terminal device.

110. The access network device as described in any one of claims 100-109, characterized in that, The access network equipment also includes: The first receiving unit is configured to receive a handover request sent by the source access network device, wherein the handover request carries configuration information of the SDAP layer and / or PDCP layer in the source access network device for communicating with the terminal device.

111. The access network device as described in claim 109 or 110, characterized in that, The access network equipment also includes: The second receiving unit is configured to receive first information sent by the source access network device, wherein the first information carries one or more of the following: PDCP SDU to be sent; PDCP SDU sent but not yet acknowledged; The COUNT value associated with a PDCP SDU that has been sent but not yet acknowledged; Received PDCP SDU; Status information of the PDCP SDU to be received.

112. The access network device as described in any one of claims 108-111, characterized in that, The switching command carries configuration information for one or more protocol layers, which are protocol layers in the target access network device used to communicate with the terminal device, excluding the SDAP layer and / or PDCP layer used to communicate with the terminal device.

113. The access network equipment as described in any one of claims 103, 106-111, characterized in that, The protocol stack in the first access network device used for communication with the terminal device includes a first protocol layer, which is the protocol layer of the RAT corresponding to the first access network device.

114. The access network device as described in claim 113, characterized in that, In the protocol stack used for communication with the terminal device in the first access network device, the first protocol layer is located between the SDAP layer and the MAC layer of the first access network device, and the SDAP layer of the first access network device includes a first SDAP layer or a second SDAP layer.

115. The access network device as described in claim 113 or 114, characterized in that, The length of the SN in the first protocol layer of the source access network device is the same as the length of the SN in the protocol layer of the target access network device, and / or The length of the HFN in the first protocol layer of the source access network device is the same as the length of the HFN in the protocol layer of the target access network device.

116. The access network device as described in any one of claims 113-115, characterized in that, The receiving unit is further configured to: The system receives second information sent by the source access network device, the second information carrying the SDU of the first protocol layer and / or the COUNT value corresponding to the SDU of the first protocol layer.

117. A terminal device, characterized in that, The device includes a transceiver, a memory, and a processor. The memory stores a program, and the processor invokes the program in the memory and controls the transceiver to receive or send signals so that the terminal device performs the method as described in any one of claims 1-24.

118. An access network device, characterized in that, The device includes a transceiver, a memory, and a processor. The memory stores a program, and the processor invokes the program in the memory and controls the transceiver to receive or transmit signals so that the access network device performs the method as described in any one of claims 25-58.

119. An apparatus, characterized in that, Includes a processor for calling a program from memory to cause the device to perform the method as described in any one of claims 1-58.

120. A chip, characterized in that, Includes a processor for calling a program from memory, causing a device on which the chip is mounted to perform the method as described in any one of claims 1-58.

121. A computer-readable storage medium, characterized in that, It contains a program that causes a computer to perform the method as described in any one of claims 1-58.

122. A computer program product, characterized in that, Includes a program that causes a computer to perform the method as described in any one of claims 1-58.

123. A computer program, characterized in that, The computer program causes the computer to perform the method as described in any one of claims 1-58.

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