Communication method and apparatus

Abstract

Disclosed in the embodiments of the present application are a communication method and an apparatus. The method comprises: a first access network device receiving a first request sent by a second access network device, the first request being used for requesting a handover from a cell of the second access network device to a cell of the first access network device, the first request comprising first instruction information, and the first instruction information being used for instructing inheriting transport layer information for data transfer to a candidate access network device; and, on the basis of the transport layer information, establishing a data forwarding tunnel with the candidate access network device. Using the embodiments of the present application can avoid processes of applying for handover resources, shorten handover time, and improve handover efficiency.

Description

Communication method and device

[0001] This application claims priority to the Chinese patent application with application number 202311279891.4 filed with the State Intellectual Property Office of China on September 28, 2023, and priority to the Chinese patent application with the invention name “A Communication Method and Device”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0003] Since traditional terrestrial networks (TNs) cannot provide seamless coverage for user equipment (UE), especially in places where base stations cannot be deployed, such as the ocean, desert, and air, non-terrestrial networks (NTNs) have been introduced into the Internet of Things (IoT) and the fifth-generation mobile communication technology (5G) system, as well as subsequent evolved system architectures such as 6G. By deploying base stations or part of the base station functions on non-terrestrial network equipment such as high-altitude platforms or satellites, seamless coverage is provided for UEs, thereby improving system reliability.

[0004] In the networking of NTN and TN, the XN interface between NTN and TN is very likely to not exist. Therefore, if switching is required between NTN and TN, switching preparation must be performed through the NG interface. However, the switching preparation of the NG interface may go through multiple satellites, gateway stations and core networks. The entire process may take up to hundreds of milliseconds, resulting in a long switching preparation time.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a communication method and apparatus that can reduce the process of applying for switching resources, shorten switching time, and improve switching efficiency.

[0007] In a first aspect, an embodiment of the present application provides a communication method, which is applied to a first access network device, or a chip or circuit configured in the first access network device, including:

[0008] receiving a first request sent by a second access network device, where the first request is used to request switching from a cell of the second access network device to a cell of the first access network device, and the first request includes first indication information, where the first indication information is used to indicate inheriting transport layer information for data transfer to a candidate access network device;

[0009] Based on the transport layer information, a data forwarding tunnel is established with the candidate access network device.

[0010] By pre-applying for transport layer information for data transfer to a candidate access network device, during a handover from the second access network device's cell to the first access network device's cell, the second access network device instructs the second access network device to inherit the transport layer information for data transfer to the candidate access network device. This allows the first access network device to execute the handover from the first access network device's cell to the candidate access network device's cell without having to apply for the transport layer information for data transfer to the candidate access network device. This reduces the handover resource application process, shortens handover time, and improves handover efficiency.

[0011] In one possible design, the first request includes the transport layer information. The transport layer information for data transfer to the candidate access network device included in the first request may be first indication information. That is, if the first request includes the transport layer information for data transfer to the candidate access network device, it may implicitly indicate the inheritance of the transport layer information for data transfer to the candidate access network device. After receiving the first request, the first access network device determines that the first request includes the transport layer information for data transfer to the candidate access network device, and then inherits the transport layer information for data transfer to the candidate access network device.

[0012] In one possible design, the first request also includes second indication information, where the second indication information is used to indicate that pre-configuration information of the cell of the candidate access network device is retained, and the pre-configuration information is used to access the cell of the candidate access network device.

[0013] By applying for the pre-configuration information of the candidate access network device's cell in advance, during the process of switching from the second access network device's cell to the first access network device's cell, the second access network device instructs the user to retain the pre-configuration information of the candidate access network device's cell. This allows the user to switch from the first access network device's cell to the candidate access network device's cell without the first access network device having to apply for the pre-configuration information of the candidate access network device. This reduces the process of applying for handover resources, shortens handover time, and improves handover efficiency.

[0014] In one possible design, the first request includes pre-configuration information of a cell of a candidate access network device. The pre-configuration information of the cell of the candidate access network device included in the first request may be second indication information. That is, if the first request includes pre-configuration information of the cell of the candidate access network device, it may implicitly indicate that the pre-configuration information of the cell of the candidate access network device is retained. After receiving the first request, the first access network device determines that the first request includes pre-configuration information of the cell of the candidate access network device, and then retains the pre-configuration information of the cell of the candidate access network device.

[0015] In one possible design, the pre-configuration information includes pre-configuration information based on conditional switching CHO, and / or pre-configuration information based on L1 / L2 triggered mobility LTM switching. That is, the second access network device can apply for the pre-configuration information of the cell of the candidate access network device through the CHO switching process or the LTM switching process, and send the pre-configuration information of the cell of the candidate access network device to the terminal device and the first access network device. The terminal device can determine whether to access the cell of the candidate access network device according to the CHO switching trigger condition of the cell of the candidate access network device by self-evaluation in the CHO switching process. Alternatively, the first access network device determines whether to switch to the cell of the candidate access network device according to the measurement report based on the cell of the candidate access network device in the LTM switching process. If the terminal device or the first access network device determines to switch to the cell of the candidate access network device, the cell of the candidate access network device is accessed based on the pre-configuration information.

[0016] In one possible design, the first access network device sends first information to the second access network device, where the first information is used to indicate confirmation of inheriting the transport layer information for data transfer to the candidate access network device.

[0017] In one possible design, the transport layer information includes transport layer information on the core network side. For example, when the handover with the cell of the candidate access network device is an Ng handover, the transport layer information is the transport layer information on the core network side.

[0018] In one possible design, the transport layer information includes the transport layer information of the candidate access network device side. For example, when the handover with the cell of the candidate access network device is an Xn handover, the transport layer information is the transport layer information of the candidate access network device side.

[0019] In one possible design, the first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is an NT base station, and the candidate access network device is an NTN base station.

[0020] In a second aspect, an embodiment of the present application provides a communication method, which is applied to a second access network device, or a chip or circuit configured in the second access network device, including:

[0021] Obtaining transport layer information for transferring data to candidate access network devices;

[0022] A first request is sent to a first access network device, where the first request is used to request switching from the cell of the second access network device to the cell of the first access network device, and the first request includes first indication information, where the first indication information is used to indicate inheritance of transport layer information for data transfer to the candidate access network device.

[0023] By pre-applying for transport layer information for data transfer to a candidate access network device, during a handover from the second access network device's cell to the first access network device's cell, the second access network device instructs the second access network device to inherit the transport layer information for data transfer to the candidate access network device. This allows the first access network device to execute the handover from the first access network device's cell to the candidate access network device's cell without having to apply for the transport layer information for data transfer to the candidate access network device. This reduces the handover resource application process, shortens handover time, and improves handover efficiency.

[0024] In one possible design, the first request includes the transport layer information. The transport layer information for data transfer to the candidate access network device included in the first request may be first indication information. That is, if the first request includes the transport layer information for data transfer to the candidate access network device, it may implicitly indicate the inheritance of the transport layer information for data transfer to the candidate access network device. After receiving the first request, the first access network device determines that the first request includes the transport layer information for data transfer to the candidate access network device, and then inherits the transport layer information for data transfer to the candidate access network device.

[0025] In one possible design, the first request also includes second indication information, where the second indication information is used to indicate that pre-configuration information of the cell of the candidate access network device is retained, and the pre-configuration information is used to access the cell of the candidate access network device.

[0026] By applying for pre-configuration information of the candidate access network device's cell in advance, during the process of switching from the second access network device's cell to the first access network device's cell, the second access network device instructs the user to retain the pre-configuration information of the candidate access network device's cell. This allows the user to switch from the first access network device's cell to the candidate access network device's cell without having to apply for the pre-configuration information of the candidate access network device's cell. This reduces the process of applying for handover resources, shortens handover time, and improves handover efficiency.

[0027] In one possible design, the first request includes pre-configuration information of a cell of a candidate access network device. The pre-configuration information of the cell of the candidate access network device included in the first request may be second indication information. That is, if the first request includes pre-configuration information of the cell of the candidate access network device, it may implicitly indicate that the pre-configuration information of the cell of the candidate access network device is retained. After receiving the first request, the first access network device determines that the first request includes pre-configuration information of the cell of the candidate access network device, and then retains the pre-configuration information of the cell of the candidate access network device.

[0028] In one possible design, the pre-configuration information includes pre-configuration information based on conditional switching CHO, and / or pre-configuration information based on L1 / L2 triggered mobility LTM switching. That is, the second access network device can apply for the pre-configuration information of the cell of the candidate access network device through the CHO switching process or the LTM switching process, and send the pre-configuration information of the cell of the candidate access network device to the terminal device and the first access network device. The terminal device can determine whether to access the cell of the candidate access network device according to the CHO switching trigger condition of the cell of the candidate access network device by self-evaluation in the CHO switching process. Alternatively, the first access network device determines whether to switch to the cell of the candidate access network device according to the measurement report based on the cell of the candidate access network device in the LTM switching process. If the terminal device or the first access network device determines to switch to the cell of the candidate access network device, the cell of the candidate access network device is accessed based on the pre-configuration information.

[0029] In one possible design, first information sent by the first access network device is received, where the first information is used to indicate confirmation of inheriting the transport layer information for data transfer to the candidate access network device.

[0030] In one possible design, the second access network device sends second information to the terminal device, where the second information is used to instruct a switch from the cell of the second access network device to the cell of the first access network device. The second information includes third indication information, where the third indication information is used to instruct the terminal device to retain the pre-configuration information of the cell of the candidate access network device. By instructing the terminal device to retain the pre-configuration information of the cell of the candidate access network device, during the process of switching from the cell of the first access network device to the cell of the candidate access network device, the terminal device accesses the cell of the candidate access network device through the pre-configuration information of the cell of the candidate access network device, thereby ensuring successful switching.

[0031] In one possible design, the second access network device sends pre-configuration information of the cell of the candidate access network device to the terminal device.

[0032] In one possible design, the first access network device sends first information to the second access network device, where the first information is used to indicate confirmation of inheriting the transport layer information for data transfer to the candidate access network device.

[0033] In one possible design, the transport layer information includes transport layer information on the core network side. For example, when the handover with the cell of the candidate access network device is an Ng handover, the transport layer information is the transport layer information on the core network side.

[0034] In one possible design, the first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is an NT base station, and the candidate access network device is an NTN base station.

[0035] In a third aspect, an embodiment of the present application provides a communication method, which is applied to a terminal device, or a chip or circuit configured in the terminal device, including:

[0036] receiving second information sent by a second access network device, where the second information includes third indication information, where the third indication information is used to indicate that pre-configured information of a cell of the candidate access network device is retained;

[0037] After switching from the cell of the second access network device to the cell of the first access network device, the pre-configuration information of the cell of the candidate access network device is retained, and the pre-configuration information is used to access the cell of the candidate access network device.

[0038] By instructing the terminal device to retain the pre-configuration information of the cell of the candidate access network device, during the process of switching from the cell of the first access network device to the cell of the candidate access network device, the cell of the candidate access network device is accessed through the pre-configuration information of the cell of the candidate access network device, thereby ensuring successful switching.

[0039] In one possible design, pre-configuration information of the cell of the candidate access network device sent by the second access network device is received.

[0040] In one possible design, the pre-configuration information includes pre-configuration information based on conditional handover (CHO) and / or pre-configuration information based on L1 / L2 triggered mobility (LTM) handover.

[0041] In one possible design, the first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is an NT base station, and the candidate access network device is an NTN base station.

[0042] In a fourth aspect, an embodiment of the present application provides a communication device, the communication device comprising:

[0043] a receiving module, configured to receive a first request sent by a second access network device, where the first request is used to request switching from a cell of the second access network device to a cell of the first access network device, where the first request includes first indication information, where the first indication information is used to indicate inheritance of transport layer information for data transfer to a candidate access network device;

[0044] A processing module is used to establish a data forwarding tunnel with the candidate access network device based on the transport layer information.

[0045] In one possible design, the first request includes the transport layer information.

[0046] In one possible design, the first request also includes second indication information, where the second indication information is used to indicate that pre-configuration information of the cell of the candidate access network device is retained, and the pre-configuration information is used to access the cell of the candidate access network device.

[0047] In one possible design, the first request includes the pre-configuration information.

[0048] In one possible design, the pre-configuration information includes pre-configuration information based on conditional handover (CHO) and / or pre-configuration information based on L1 / L2 triggered mobility (LTM) handover.

[0049] In one possible design, the device further includes:

[0050] A sending module is used to send first information to the second access network device, where the first information is used to indicate confirmation of inheriting the transport layer information for data transfer to the candidate access network device.

[0051] In one possible design, the transport layer information includes transport layer information on the core network side.

[0052] In one possible design, the transport layer information includes transport layer information on the candidate access network device side.

[0053] In one possible design, the first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is an NT base station, and the candidate access network device is an NTN base station.

[0054] The operations and beneficial effects performed by the communication device can refer to the method and beneficial effects described in the first aspect above, and the repeated parts will be omitted.

[0055] In a fifth aspect, an embodiment of the present application provides a communication device, the communication device comprising:

[0056] A receiving module, configured to obtain transport layer information for transferring data to a candidate access network device;

[0057] A sending module is used to send a first request to a first access network device, where the first request is used to request switching from a cell of a second access network device to a cell of the first access network device, and the first request includes first indication information, where the first indication information is used to indicate inheritance of transport layer information for data transfer to the candidate access network device.

[0058] In one possible design, the first request includes the transport layer information.

[0059] In one possible design, the first request also includes second indication information, where the second indication information is used to indicate that pre-configuration information of the cell of the candidate access network device is retained, and the pre-configuration information is used to access the cell of the candidate access network device.

[0060] In one possible design, the first request includes the pre-configuration information.

[0061] In one possible design, the pre-configuration information includes pre-configuration information based on conditional handover (CHO) and / or pre-configuration information based on L1 / L2 triggered mobility (LTM) handover.

[0062] In one possible design, the receiving module is further used to receive first information sent by the first access network device, where the first information is used to indicate confirmation of inheriting the transport layer information for data transfer to the candidate access network device.

[0063] In one possible design, the sending module is also used to send second information to the terminal device, where the second information is used to indicate switching from the cell of the second access network device to the cell of the first access network device, and the second information includes third indication information, where the third indication information is used to indicate retaining the pre-configuration information of the cell of the candidate access network device.

[0064] In one possible design, the sending module is also used to send pre-configuration information of the cell of the candidate access network device to the second access network device and the terminal device.

[0065] In one possible design, the transport layer information includes address information on the core network side.

[0066] In one possible design, the transport layer information includes transport layer information on the candidate access network device side.

[0067] In one possible design, the first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is an NT base station, and the candidate access network device is an NTN base station.

[0068] The operations and beneficial effects performed by the communication device can refer to the method and beneficial effects described in the second aspect above, and the repeated parts will be omitted.

[0069] In a sixth aspect, an embodiment of the present application provides a communication device, the communication device comprising:

[0070] a receiving module, configured to receive second information sent by a second access network device, where the second information includes third indication information, where the third indication information is used to indicate that pre-configured information of a cell of the candidate access network device is retained;

[0071] The processing module is used to retain the pre-configuration information of the cell of the candidate access network device after switching from the cell of the second access network device to the cell of the first access network device, where the pre-configuration information is used to access the cell of the candidate access network device.

[0072] In one possible design, the receiving module is further used to receive pre-configuration information of the cell of the candidate access network device sent by the second access network device.

[0073] In one possible design, the pre-configuration information includes pre-configuration information based on conditional handover (CHO) and / or pre-configuration information based on L1 / L2 triggered mobility (LTM) handover.

[0074] In one possible design, the first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is an NT base station, and the candidate access network device is an NTN base station.

[0075] The operations and beneficial effects performed by the communication device can refer to the method and beneficial effects described in the third aspect above, and the repeated parts will be omitted.

[0076] In the seventh aspect, the present application provides a communication device, which includes a processor and a memory, the memory being used to store a computer program; the processor being used to execute the computer program stored in the memory so that the communication device performs the method as described in any one of the first aspects.

[0077] In an eighth aspect, the present application provides a communication device, comprising a processor and a memory, wherein the memory is used to store a computer program; the processor is used to execute the computer program stored in the memory so that the communication device performs a method as described in any one of the second aspects.

[0078] In the ninth aspect, the present application provides a communication device, which includes a processor and a memory, the memory being used to store a computer program; the processor being used to execute the computer program stored in the memory so that the communication device performs a method as described in any one of the third aspects.

[0079] In a tenth aspect, the present application provides a communication device, which may be a first access network device, or a device in the first access network device, or a device that can be used in conjunction with the first access network device. The communication device may also be a chip system. The communication device may execute the method described in the first aspect. The functions of the communication device may be implemented by hardware, or by hardware executing corresponding software implementations. The hardware or software includes one or more modules corresponding to the above functions. The module may be software and / or hardware. The operations and beneficial effects performed by the communication device may refer to the methods and beneficial effects described in the first aspect above, and repetitive parts will not be repeated.

[0080] In the eleventh aspect, the present application provides a communication device, which may be a second access network device, or a device in the second access network device, or a device that can be used in conjunction with the second access network device. The communication device may also be a chip system. The communication device may execute the method described in the second aspect. The functions of the communication device may be implemented by hardware, or by hardware executing corresponding software implementations. The hardware or software includes one or more modules corresponding to the above functions. The module may be software and / or hardware. The operations and beneficial effects performed by the communication device can refer to the method and beneficial effects described in the second aspect above, and repetitive parts will not be repeated.

[0081] In the twelfth aspect, the present application provides a communication device, which may be a terminal device, a device in a terminal device, or a device that can be used in conjunction with a terminal device. The communication device may also be a chip system. The communication device may execute the method described in the third aspect. The functions of the communication device may be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. The module may be software and / or hardware. The operations and beneficial effects performed by the communication device may refer to the method and beneficial effects described in the third aspect above, and the repeated parts will not be repeated.

[0082] In a thirteenth aspect, the present application provides a computer-readable storage medium for storing a computer program. When the computer program is executed, the method described in any one of the first to third aspects is implemented.

[0083] In a fourteenth aspect, the present application provides a computer program product comprising a computer program, which, when executed, enables the method described in any one of the first to third aspects to be implemented.

[0084] In the fifteenth aspect, an embodiment of the present application provides a communication system, which includes at least one terminal device and at least one access network device, the access network device is used to execute the steps in the above-mentioned first aspect or second aspect, and the terminal device is used to execute the steps in the above-mentioned third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the accompanying drawings required in the embodiments of the present application or the background technology will be described below.

[0086] FIG1 is a schematic diagram of a communication system provided in an embodiment of the present application;

[0087] FIG2 is a schematic diagram of a CU-DU network structure;

[0088] FIG3 is a schematic diagram of the architecture of a transparent satellite;

[0089] FIG4 is a schematic diagram of the architecture of a regenerative satellite;

[0090] FIG5 is a schematic diagram of an LTM switching;

[0091] FIG6 is a schematic diagram of another LTM switching;

[0092] FIG7 is a schematic diagram of a CHO process;

[0093] FIG8 is a schematic diagram of switching between NTN and TN;

[0094] FIG9 is a flow chart of a communication method provided in an embodiment of the present application;

[0095] FIG10 is a flow chart of another communication method provided in an embodiment of the present application;

[0096] FIG11 is a flow chart of another communication method provided in an embodiment of the present application;

[0097] FIG12 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0098] FIG13 is a schematic structural diagram of an access network device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0099] As shown in Figure 1, Figure 1 is a schematic diagram of a communication system provided by an embodiment of the present application. The communication system mainly includes terminal equipment, core network equipment and access network equipment. Among them:

[0100] Terminal devices, also known as user equipment (UE), mobile stations (MS), and mobile terminals (MT), refer to devices that provide voice and / or data connectivity to users. Examples include handheld devices and in-vehicle devices with wireless connectivity. Currently, some examples of terminals include: mobile phones, tablets, laptops, PDAs, mobile internet devices (MIDs), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals in self-driving cars, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, and wireless terminals in smart homes.

[0101] Access network equipment refers to the radio access network (RAN) node (or device) that connects terminals to the wireless network. It can also be called a base station. Examples of RAN nodes include the evolved Node B (gNB), radio network controller (RNC), Node B (NB), base station controller (BSC), base transceiver station (BTS), home evolved Node B (HNB), base band unit (BBU), and wireless fidelity (Wi-Fi) access point (AP).

[0102] The access network equipment and terminal equipment can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; can also be deployed on the water; and can also be deployed in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of the access network equipment and terminal equipment.

[0103] As shown in Figure 2, a schematic diagram of the CU-DU network architecture is provided. Access network equipment may include centralized unit (CU) nodes, distributed unit (DU) nodes, or RAN equipment including CU and DU nodes. The RAN equipment including CU and DU nodes splits the protocol layers of the gNB in ​​the NR system, centrally controlling some protocol layer functions in the CU and distributing some or all of the remaining protocol layer functions in the DU, which is then centrally controlled by the CU. Furthermore, the centralized unit (CU) can be further divided into the control plane (CU-CP) and the user plane (CU-UP). The CU-CP is responsible for control plane functions, primarily including RRC and the control plane's corresponding packet data convergence protocol (PDCP), also known as PDCP-C. PDCP-C is primarily responsible for encryption, decryption, integrity protection, and data transmission of control plane data. The CU-UP is responsible for user plane functions, primarily including SDAP and the user plane's corresponding PDCP, also known as PDCP-U. SDAP is primarily responsible for processing core network data and mapping flows to bearers. The PDCP-U is primarily responsible for data plane encryption and decryption, integrity protection, header compression, sequence number maintenance, and data transmission. The CU-CP and CU-UP are connected via the E1 interface. The CU-CP represents the gNB's connection to the core network via the NG interface. It connects to the DU via the F1 control plane, or F1-C. The CU-UP connects to the DU via the F1 user plane, or F1-U. Alternatively, the PDCP-C may also reside in the CU-UP.

[0104] Core network equipment refers to equipment in the core network (CN) that provides service support for terminals. At present, some examples of core network equipment are: access and mobility management function (AMF) entity, session management function (SMF) entity, user plane function (UPF) entity, etc., which are not listed here one by one. Among them, the AMF entity can be responsible for terminal access management and mobility management; the SMF entity can be responsible for session management, such as user session establishment, etc.; the UPF entity can be a functional entity of the user plane, mainly responsible for connecting to the external network. It should be noted that the entity in this application can also be referred to as a network element or a functional entity. For example, the AMF entity can also be referred to as an AMF network element or an AMF functional entity. For another example, the SMF entity can also be referred to as an SMF network element or an SMF functional entity, etc.

[0105] The communication system can be applicable to a long term evolution (LTE) system, a universal mobile telecommunications system (UMTS) system, a code division multiple access (CDMA) system, a wireless local area network (WLAN) or a fifth generation mobile communication system (5G) or a next generation wireless communication system, etc.

[0106] NTN is a communication technology enabled by non-terrestrial network equipment. NTN systems can include satellite systems, drones, and high-altitude platform stations (HAPS). NTN communications offer advantages such as wide coverage, long communication distances, high reliability, flexibility, and high throughput. Unaffected by geographical conditions, climate conditions, and natural disasters, NTN has been widely used in aviation, maritime, and military communications. Introducing NTN into future fifth-generation mobile networks (5G) will significantly improve user experience. On the one hand, NTN can provide communication services in areas difficult to reach by terrestrial networks, such as oceans, forests, deserts, and remote areas. On the other hand, NTN can enhance the reliability of 5G communications, providing more stable communication services for users in high-speed scenarios such as trains and airplanes. Furthermore, NTN can provide more data transmission resources and support a greater number of connections. Thanks to the concept of "anytime, anywhere" communication, the importance of NTN will continue to rise in the future.

[0107] Generally speaking, the higher the satellite's orbit, the greater its coverage area, but also the longer the communication latency. Based on their orbital altitude, satellites can be categorized as: Low Earth Orbit (LEO), with an orbital altitude of 160 to 2000 km; Medium Earth Orbit (MEO), with an orbital altitude of 2000 to 35,786 km; and High Earth Orbit (GEO), also known as Geostationary Earth Orbit (GEO), with an orbital altitude of 35,786 km. GEO is a geostationary orbit, in which satellites remain stationary relative to the Earth. LEO and MEO are collectively referred to as non-geostationary orbits (NGSO), in which satellites move at high speed relative to the Earth.

[0108] NGSOs are further categorized as Earth Moving Cells and Earth Fixed Cells, depending on whether the satellite's beam moves with it. In Earth Moving Cells, the cell moves relative to the ground, and the satellite's beam pointing direction follows the satellite's movement. In Earth Fixed Cells, the cell remains fixed relative to the ground for a specified period of time, and the satellite antenna uses its beamforming capabilities to keep the beam pointing to a fixed area on the ground for a specified period of time.

[0109] Satellites can generally be divided into two categories according to their working modes, including:

[0110] Figure 3 shows a schematic diagram of the transparent satellite architecture. The satellite transparently forwards cell information from ground network equipment (such as base stations). The satellite performs radio frequency filtering, frequency conversion, and amplification. In other words, the satellite primarily acts as an L1 relay, regenerating physical layer signals and lacks any higher protocol layer functionality.

[0111] Figure 4 shows a schematic diagram of the architecture of a regenerative satellite. In regenerative mode, the satellite performs the processing functions of a base station. Regenerative satellites in this mode can be categorized as either non-intersatellite links (ISLs) or with ISLs, where the satellites have an interface for direct data exchange, typically an Xn port. Another architecture involves the satellite performing the DU processing functions of a base station, effectively acting as a DU.

[0112] It should be noted that Figures 3 and 4 only illustrate one satellite and one NTN gateway. In actual use, an architecture with multiple satellites and / or multiple NTN gateways may be adopted as needed. Each satellite may provide services to one or more terminal devices, each NTN gateway may correspond to one or more satellites, and each satellite may correspond to one or more NTN gateways, although this embodiment of the present application does not specifically limit this.

[0113] It should be noted that FIG3 and FIG4 are merely examples of NTN scenarios. NTN scenarios may also include other specific scenarios, which are not limited in this application.

[0114] It should be noted that the embodiments of the present application can be used in transparent satellite architecture and regenerative satellite architecture, and can also be used in Earth Moving Cell and Quasi-Earth Fixed Cell scenarios.

[0115] L1 / L2 triggered mobility (LTM) handover primarily involves L1 and / or L2, with handover-related operations primarily performed at L1 and L2. L1 refers to the physical layer, and L2 refers to one or more layers among the media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and service data adaptation protocol (SDAP). L1 / L2 can also be understood as L1 and / or L2. For example, a terminal device sends L1 measurement results to an access network device via physical layer control signaling, carried on the physical uplink control channel (PUCCH). The access network device reads the L1 measurement results, makes a handover decision based on them, and sends the handover decision to the terminal device via L1 / L2 signaling. The L1 / L2 signaling may be carried on a physical downlink control channel (PDCCH) or a media access control protocol control element (MAC CE).

[0116] LTM handover refers to handover-related operations primarily performed at the physical and MAC layers. However, it should be understood that LTM handover also involves the participation of other protocol layers, such as the RRC layer (also known as L3). This application document does not limit the specific name of the handover technology; L1 / L2 handover may also be referred to as bottom layer handover or lower layer handover.

[0117] L1 / L2 handover is applicable to: (1) cross-DU cell handover within the same CU (i.e., the source cell and target cell belong to different DUs under the same CU); (2) cell handover within the same DU (i.e., the source cell and target cell belong to the same DU). It may be introduced into NTN in the future, such as NTN to TN handover, or NTN to NTN handover, and may also be introduced into more scenarios. Although the specific signaling interaction content of L1 / L2 handover in the above different scenarios is different, the basic concept is the same.

[0118] As shown in Figure 5, Figure 5 is a schematic diagram of LTM handover. In the cell handover scenario within the same DU under the CU-DU separation architecture, the UE switches from the source cell (cell1) to the target cell (cell2) through LTM handover. The main steps are as follows:

[0119] S501: The CU sends configuration information of LTM candidate cells to the UE. It should be understood that the CU sends the configuration information to the UE via the DU.

[0120] S502: The UE sends the measurement result to the access network device (DU in the figure) to which the source cell belongs.

[0121] Specifically, the UE measures the reference signals of the source cell and / or candidate cells according to the configuration information, obtains the measurement results, and then reports the measurement results to the DU.

[0122] The measurement results include at least one of the following: an L1 measurement result of a source cell and an L1 measurement result of at least one candidate cell. The L1 measurement results of the source cell and / or candidate cell may be cell-level measurement results, such as cell-level reference signal received power (RSRP), or beam-level measurement results, such as beam-level RSRP.

[0123] S503: The DU sends a handover command to the UE.

[0124] Specifically, after receiving the measurement result, the DU determines whether to switch based on the measurement result. If switching is determined, a handover command is sent to the UE.

[0125] For example, when the signal quality of a candidate cell is better than that of the source cell, a handover is determined to be made to the candidate cell, which is also referred to as the target cell. The DU sends a handover command to the UE. The handover command is an LTM handover command, which is L1 / L2 signaling.

[0126] The handover command may include the identity information of the target cell, or the identity information associated with the target cell. Furthermore, the handover command may also carry indication information, which is used to indicate the beam information that the UE should use when communicating with the target cell.

[0127] S504: The UE accesses the target cell in the DU.

[0128] Specifically, the UE performs handover according to the configuration information of the target cell received in step S501, accesses the target cell of the DU, and begins uplink and downlink data transmission with the target cell after successful access. Furthermore, the UE may use the beam information indicated in step S503 to perform uplink and downlink data transmission with the target cell. In this application document, communication between the UE and the target cell can be understood as communication between the UE and the access network device to which the target cell belongs.

[0129] Furthermore, the UE may access the target cell using a random access channel (RACH) or a RACH-less method.

[0130] S505 , the DU sends notification information to the CU, where the notification information is used to indicate that the UE has successfully completed the LTM handover.

[0131] The notification information may include identification information associated with the target cell identity.

[0132] As shown in Figure 6, Figure 6 is a schematic diagram of another LTM switching. Under the CU-DU separation architecture, in the cell switching scenario between different DUs under the same CU, the UE switches from the source DU to the target DU through LTM switching. The difference from the steps shown in Figure 5 is: in S601, the CU establishes a UE context with the target DU, obtains the configuration information of the cell of the target DU as the configuration information of the candidate cell, and sends the configuration information of the candidate cell to the UE in S602. Finally, the UE accesses the target cell of the target DU in S605. For other steps, please refer to Figure 5 and will not be repeated here.

[0133] It should be understood that the target DU may also be referred to as a candidate DU before the handover. When the target cell for handover to a candidate DU is determined, the candidate DU may be referred to as a target DU.

[0134] In traditional New Radio (NR) basic handover, the base station signal can be measured during the movement of the terminal device. If the signal quality of the target base station is measured to be better than that of the source base station, the terminal device can be handed over from the cell covered by the source base station to the cell covered by the target base station. However, due to the deterioration of the wireless environment between the UE and the source base station, the UE's measurement report may not reach the base station, resulting in a handover failure. At this time, the UE will recognize the radio link failure and initiate the RRC re-establishment process.

[0135] In order to reduce the probability of NR basic switching, the 3rd generation partnership project (3GPP) R16 introduced conditional handover (CHO), which is an enhancement of NR basic switching. CHO can be understood as: before the wireless environment between the UE and the source base station deteriorates further, the source base station sends the switching command (carrying the CHO configuration and CHO trigger conditions of the candidate target base station) to the UE in advance, so that the UE knows how to access the target base station in advance. After waiting for the UE to find a base station that meets the CHO trigger conditions among the candidate target base stations, it can independently decide to initiate a handover, which increases the chance of successful message transmission and can greatly improve the success rate of the handover. As shown in Figure 7, Figure 7 is a schematic diagram of a CHO process. It mainly includes the following steps:

[0136] S701: The source base station sends a measurement configuration to the UE.

[0137] S702: The UE measures one or more candidate base stations (including candidate base station 1 and candidate base station 2) based on the measurement configuration, obtains measurement reports of the one or more candidate base stations, and sends the measurement reports to the source base station.

[0138] S703 : The source base station sends a first handover request to the candidate base station 1 . The first handover request is used to request CHO configuration of one or more candidate cells of the candidate base station 1 .

[0139] S704 : Candidate base station 1 sends first handover confirmation information to the source base station. The first handover confirmation information includes CHO configurations of one or more candidate cells of candidate base station 1 .

[0140] S705 : The source base station sends a second handover request to the candidate base station 2 . The second handover request is used to request CHO configuration of one or more candidate cells of the candidate base station 2 .

[0141] S706 : Candidate base station 2 sends second handover confirmation information to the source base station. The second handover confirmation information includes CHO configurations of one or more candidate cells of candidate base station 2 .

[0142] S703-S704 and S705-S706 are in no particular order.

[0143] S707: When the source link quality is good, the source base station sends CHO configuration information (pre-configured information of candidate cells) to the UE. The CHO configuration information may include CHO handover triggering conditions and related information of one or more candidate cells (information required for the UE to access the candidate cells).

[0144] The relevant information of the candidate cell may include at least one of the following: a cell-radio network temporary identifier (C-RNTI) allocated by the candidate cell to the UE, resource information of the random access channel (RACH) required to access the candidate cell, index information corresponding to the candidate cell (for example, the measurement identifier measID corresponding to the cell and / or the CHO-ConfigId corresponding to the cell), the cell global identity (CGI) of the candidate cell, the physical cell identifier (PCI) of the candidate cell, and the frequency information corresponding to the candidate cell, the physical layer configuration parameters corresponding to the candidate cell, the MAC layer configuration parameters, the RLC layer configuration parameters, the PDCP layer configuration parameters, the SDAP layer configuration parameters, the RRC layer configuration parameters, etc. Among them, the frequency information corresponding to the candidate cell includes one or more of the following: the absolute frequency of the synchronization signal block SSB (absolute frequency SSB), the absolute frequency position (absolute frequency point A) of the reference resource module (common RB0), the frequency bandwidth list (frequency band list), and the SCS-specific carrier list (scs-specific carrier list).

[0145] The CHO handover triggering condition may include a CHO execution event type and a corresponding threshold value. The CHO execution event type may include event A3, event A4, event A5, event B1, event B2 or other execution event types. A candidate cell may be configured with one or more CHO handover triggering conditions. For example, a candidate cell may be configured with one execution event type, but may be configured with at least two different threshold values ​​and / or at most two different trigger qualities (trigger quantity). The trigger quality may include reference signal received power (RSRP), reference signal received quality (RSRQ), and signal to interference plus noise ratio (SINR). Alternatively, a candidate cell may be configured with at least two different execution event types and threshold values ​​corresponding to each execution event type. The CHO execution event types corresponding to different candidate cells may be the same or different. The threshold values ​​corresponding to different candidate cells may be the same or different, without limitation.

[0146] S708: The UE determines whether the candidate cell meets the handover triggering condition according to the CHO configuration information, and selects a candidate cell that meets the handover triggering condition as the target cell.

[0147] For example, for candidate cell A, the configured CHO execution event type is an A3 event, and the configured corresponding threshold value is a first threshold value. When the cell signal quality of candidate cell A is higher than the first threshold value of the cell signal quality of the serving cell, it can be considered that candidate cell A meets the CHO handover trigger condition, and candidate cell A can be determined as the target cell. Specifically, for example, for candidate cell A, an A3 event is configured, and two trigger qualities are configured, such as RSRP and RSRQ. The configured first threshold value corresponding to RSRP is E, and the configured first threshold value corresponding to RSRQ is F. Then, when the RSRP of candidate cell A is higher than the RSRP of the serving cell by E, and the RSRQ of candidate cell A is higher than the RSRQ of the serving cell by F, it can be considered that candidate cell A meets the CHO handover trigger condition, and candidate cell A can be determined as the target cell. For another example, corresponding to candidate cell B, if the configured CHO execution event type is an A5 event, a trigger quality is configured, such as RSRP, and the corresponding threshold values ​​are configured as the second threshold and the third threshold, then when the RSRP of candidate cell B is higher than the second threshold and the RSRP of the serving cell is lower than the third threshold, it can be considered that candidate cell B meets the CHO switching trigger condition, and the candidate cell B can be determined as the target cell.

[0148] S709: The UE accesses the target cell, for example, by performing a random access procedure.

[0149] S710, the UE sends an RRC message (such as an RRC reconfiguration complete message) to the base station to which the target cell belongs (ie, the target base station). The RRC message is used to notify the target base station that the conditional handover is completed.

[0150] Figure 8 is a schematic diagram of handover between NTN and TN. In NTN and TN networking, the Xn interface between the NTN and TN networks is highly unlikely to exist. Therefore, handover preparation between the NTN and TN networks requires the Ng interface. This Ng interface preparation may involve multiple satellites, gateway stations, and the core network. The entire process can take up to several hundred milliseconds, resulting in a very long handover preparation time.

[0151] Taking NTN (where NTN is a satellite) to TN handover as an example, when the pre-configuration information of a candidate TN cell is delivered to the UE but the UE does not switch to the candidate TN cell, the source satellite switches the UE to the target satellite due to the rapid movement of the satellite. In the prior art, the pre-configuration information of the candidate TN cell needs to be released when the handover occurs or after the handover is completed. However, after the handover is successful, the target satellite will likely need to re-apply for the pre-configuration information of the candidate TN cell for the UE to switch to the candidate TN cell. This re-application process wastes time and is not conducive to the UE switching to the candidate TN target cell in a timely manner.

[0152] In order to solve the above technical problems, the embodiments of the present application provide the following solutions.

[0153] The embodiments of the present application involve Ng switching and Xn switching. The following explains Ng switching and Xn switching:

[0154] Xn handover: Xn is the interface between two access network devices. When an Xn interface exists between two access network devices, the two devices can perform handover directly through the Xn interface. Specifically, the source access network device sends a handover request to the target access network device and receives a handover confirmation from the target access network device. Data transfer does not require passing through the core network, so only the transport layer information of the candidate access network device is required.

[0155] Ng switching: When the switching cannot be completed through the Xn interface, the switching is completed through the Ng interface. When the source access network device needs to apply for the switching resources of a terminal device from the target access network device, the source access network device sends a switching request to the core network device. After the core network device receives the switching request, it sends the switching request to the target access network device. The core network device may need to forward during this process. When data is transferred, the source access network device is also required to send the transferred data to the core network device, and then the core network device sends the transferred data to the target access network device. Therefore, for the source access network device, it is necessary to know the transport layer information of the next-hop core network side when transferring data. For the core network side, it is necessary to know the transport layer information of the candidate access network device.

[0156] As shown in Figure 9, Figure 9 is a flow chart of a communication method provided in an embodiment of the present application. The method in the embodiment of the present application includes the following steps:

[0157] S901, a first access network device receives a first request sent by a second access network device, where the first request is used to request switching from a cell of the second access network device to a cell of the first access network device, and the first request includes first indication information, where the first indication information is used to indicate inheritance of transport layer information for data transfer to the candidate access network device.

[0158] The first request may be a handover request. The transport layer information may include transport layer information on the core network side or transport layer information on the candidate access network device side. When the handover to the cell of the candidate access network device is an Xn handover, the transport layer information is the transport layer information on the candidate access network device side; when the handover to the cell of the candidate access network device is an Ng handover, the transport layer information is the transport layer information on the core network side. Furthermore, the transport layer information may include an IP address and a port number.

[0159] Optionally, the first request may include transport layer information for transferring data to the candidate access network device (i.e., when the first access network device transfers data to the candidate access network device through the core network, the transport layer information on the core network side or the transport layer information on the candidate access network device side).

[0160] It should be understood that the transport layer information for data transfer to the candidate access network device included in the first request may be the first indication information. That is, if the first request includes the transport layer information for data transfer to the candidate access network device, it may implicitly indicate the inheritance of the transport layer information for data transfer to the candidate access network device. After receiving the first request, the first access network device determines that the first request includes the transport layer information for data transfer to the candidate access network device, and then inherits the transport layer information for data transfer to the candidate access network device.

[0161] Optionally, the first request may further include second indication information, where the second indication information is used to indicate that the pre-configuration information allocated by the cell of the candidate access network device to the terminal device is retained, and the pre-configuration information is used by the terminal device to access the cell of the candidate access network device. Optionally, the second indication information may also be the first indication information. That is, if the first request includes the second indication information, it can implicitly indicate the inheritance of transport layer information for data transfer to the candidate access network device.

[0162] Optionally, the first request includes pre-configuration information of a cell of the candidate access network device.

[0163] It should be understood that the pre-configuration information of the candidate access network device's cell included in the first request may be the second indication information. That is, if the first request includes the pre-configuration information of the candidate access network device's cell, it may implicitly indicate that the pre-configuration information of the candidate access network device's cell is retained. After receiving the first request, the first access network device determines that the first request includes the pre-configuration information of the candidate access network device's cell, and then retains the pre-configuration information of the candidate access network device's cell.

[0164] The pre-configuration information includes information required for accessing the cell of the candidate access network device, and the pre-configuration information may include one or more of the following: the cell ID of the candidate access network device, the cell radio network temporary identifier (C-RNTI), the security algorithm ID, the key, etc. The pre-configuration information may also include dedicated random access channel (RACH) resources, the association between RACH resources and synchronization signals and PBCH blocks (synchronization signal and PBCH block synchronization signal and PBCH block, SSB), the association between RACH resources and terminal device-specific channel state information reference signal (CSI-RS) configuration, public RACH resources, system information of the cell of the candidate access network device, etc.

[0165] The pre-configuration information includes pre-configuration information based on conditional switching CHO, and / or pre-configuration information based on LTM switching. That is, the second access network device can apply for the pre-configuration information of the cell of the candidate access network device through the CHO switching process or the LTM switching process, and send the pre-configuration information of the cell of the candidate access network device to the terminal device and the first access network device. The terminal device can determine whether to access the cell of the candidate access network device according to the CHO switching trigger condition of the cell of the candidate access network device by self-evaluation in the CHO switching process. Alternatively, the first access network device determines whether to switch to the cell of the candidate access network device according to the measurement report based on the cell of the candidate access network device in the LTM switching process. If the terminal device or the first access network device determines to switch to the cell of the candidate access network device, the cell of the candidate access network device is accessed based on the pre-configuration information.

[0166] Optionally, before the second access network device sends the first request to the first access network device, the second access network device may obtain transport layer information for data transfer to the candidate access network device and pre-configured information of the cell of the candidate access network device. Specifically, the following methods may be used:

[0167] In one implementation, when Xn handover is used, the second access network device may send a handover request to one or more candidate access network devices. After receiving the handover request, the candidate access network device allocates pre-configuration information (also known as handover configuration) to the terminal device and sends a handover confirmation message to the second access network device. The handover confirmation message includes the pre-configuration information of the candidate access network device and the transport layer information on the candidate access network device side.

[0168] In another implementation, when Ng switching is adopted, the second access network device can send a first switching request to the core network device. After receiving the first switching request, the core network device sends a second switching request to one or more candidate access network devices. The candidate access network device allocates pre-configuration information (also called switching configuration) to the terminal device, and then sends a first switching confirmation message to the core network device. The first switching confirmation message may include the pre-configuration information of the candidate access network device and the transport layer information on the candidate access network device side. After receiving the first switching confirmation message, the core network device sends a second switching confirmation message to the second access network device. The second switching confirmation message may include the pre-configuration information of the candidate access network device and the transport layer information on the core network side.

[0169] In another implementation, when Ng switching is adopted, the second access network device can send a first switching request to the core network device. After receiving the first switching request, the core network device sends a second switching request to one or more candidate access network devices. The candidate access network device allocates pre-configuration information (also called switching configuration) to the terminal device, and then sends a first switching confirmation message to the core network device. The first switching confirmation message may include the pre-configuration information of the candidate access network device and the transport layer information on the candidate access network device side. After receiving the first switching confirmation message, the core network device sends a second switching confirmation message to the second access network device. The second switching confirmation message may include the pre-configuration information of the candidate access network device and the transport layer information on the candidate access network device side.

[0170] Optionally, after acquiring the pre-configuration information of the cell of the candidate access network device, the second access network device may send the pre-configuration information of the cell of the candidate access network device to the terminal device.

[0171] S902: The first access network device sends a handover confirmation message to the second access network device. The handover confirmation message is used to confirm the handover from the cell of the second access network device to the cell of the first access network device or to indicate that the first access network device has prepared resources for the handover.

[0172] Optionally, the switching confirmation information carries configuration information allocated by the first access network device to the terminal device.

[0173] Optionally, the switching confirmation information includes first information, and the first information is used to indicate confirmation of inheriting the transport layer information for data transfer to the candidate access network device.

[0174] Optionally, the first information may further include fourth indication information, where the fourth indication information is used to indicate confirmation of retaining the pre-configuration information of the cell of the candidate access network device. Based on the first information, the second access network device may determine that the first access network device inherits the transport layer information for transferring data to the candidate access network device, or determine that the first access network device retains the pre-configuration information of the cell of the candidate access network device.

[0175] S903: The first access network device establishes a data forwarding tunnel with the candidate access network device based on the transport layer information.

[0176] It can be understood that: the first access network device transfers data to the candidate access network device based on the transport layer information.

[0177] It should be noted that if the transport layer information is from the candidate access network device, the first access network device can directly establish a data forwarding tunnel with the candidate access network device. If the transport layer information is from the core network, the first access network device establishes a data forwarding tunnel with the core network based on the transport layer information from the core network. The core network establishes a data forwarding tunnel with the candidate access network device based on the transport layer information from the candidate access network device. In this way, data forwarding tunnels are established between the first access network device and the core network, and between the core network and the candidate access network device. The data forwarding tunnels are used to forward data.

[0178] S904. The second access network device sends second information to the terminal device, where the second information is used to indicate switching from the cell of the second access network device to the cell of the first access network device.

[0179] Optionally, the second information includes third indication information, and the third indication information is used to indicate that pre-configuration information of the cell of the candidate access network device is retained.

[0180] The second information may be a handover command. Optionally, the handover command carries configuration information allocated by the first access network device to the terminal device.

[0181] Optionally, if the terminal device has saved the pre-configuration information of the source cell (eg, the cell of the second access network device), the terminal device may retain the pre-configuration information of the cell of the candidate access network device and the pre-configuration information of the source cell.

[0182] Optionally, the second information also includes pre-configuration information of the cell of the candidate access network device. Optionally, the pre-configuration information of the cell of the candidate access network device included in the second information may be incremental configuration information. If the terminal device has saved the reference configuration information of the cell of the candidate access network device, the terminal device may synthesize the reference configuration information of the cell of the candidate access network device (the basic configuration information common to the cells of multiple candidate access network devices) and the incremental configuration information to obtain the synthesized pre-configuration information of the cell of the candidate access network device, and the terminal device retains the synthesized pre-configuration information of the cell of the candidate access network device.

[0183] Optionally, after the terminal device switches from the cell of the second access network device to the cell of the first access network device, the terminal device and the first access network device retain the pre-configuration information of the cell of the candidate access network device. If the pre-configuration information is pre-configuration information based on conditional switching CHO, the terminal device independently evaluates whether the cell of the candidate access network device meets the CHO switching trigger condition. If a candidate access network device meets the CHO switching trigger condition, it switches from the cell of the first access network device to the cell of the candidate access network device that meets the CHO switching trigger condition based on the pre-configuration information. If the pre-configuration information is pre-configuration information based on LTM, the first access network device determines whether to switch to the cell of the candidate access network device based on the measurement report of the cell of the candidate access network device, and the terminal device waits for the switching instruction from the first access network device.

[0184] In an embodiment of the present application, by applying in advance for pre-configured information of a candidate access network device's cell and transport layer information for data transfer to the candidate access network device, during a handover from a second access network device's cell to a first access network device's cell, the second access network device instructs the user to inherit the transport layer information for data transfer to the candidate access network device and retain the pre-configured information of the candidate access network device's cell. This allows the user to switch from the first access network device's cell to the candidate access network device's cell without having to apply for the transport layer information for data transfer to the candidate access network device and the pre-configured information of the candidate access network device's cell. This reduces the process of applying for handover resources, shortens handover time, and improves handover efficiency.

[0185] In the embodiments of the present application, the first access network device or the second access network device is a non-terrestrial network (NTN) base station, and the candidate access network device is a terrestrial network (NT) base station; alternatively, the first access network device or the second access network device is an NT base station, and the candidate access network device is an NTN base station. The following example illustrates an NTN-to-TN handover scenario. The first access network device is a first NTN base station, the second access network device is a second NTN base station, the candidate access network device is a candidate NT base station, and the terminal device is a UE. The TN-to-NTN handover scenario is similar and will not be further described here.

[0186] As shown in FIG10 , FIG10 is a flow chart of another communication method provided in an embodiment of the present application. In this embodiment of the present application, the NTN base station and the candidate TN base station are switched via the Xn interface. The main steps include:

[0187] S1001: A second NTN base station sends a first handover request to a candidate TN base station. The first handover request is used to request handover from a cell of the second NTN base station to a cell of the candidate TN base station.

[0188] S1002: The candidate TN base station sends first handover confirmation information to the second NTN base station, where the first handover confirmation information includes transport layer information of the candidate TN base station and pre-configuration information of the cell of the candidate TN base station.

[0189] In the above S1001 - S1002 , the second NTN base station may apply for the transport layer information of the candidate TN base station and the pre-configured information of the cell of the candidate TN base station through the CHO handover process or the LTM handover process.

[0190] S1003: The second NTN base station sends pre-configuration information of the cell of the candidate TN base station to the UE.

[0191] The pre-configuration information includes pre-configuration information based on conditional switching CHO and / or pre-configuration information based on LTM switching. That is, the second NTN base station can apply for the pre-configuration information of the cell of the candidate TN base station through the CHO switching process or the LTM switching process, and send the pre-configuration information of the cell of the candidate TN base station to the UE and the first NTN base station. The UE can self-evaluate the CHO switching trigger condition of the cell of the candidate TN base station in the CHO switching process to determine whether to access the cell of the candidate TN base station. Alternatively, the first NTN base station determines whether to switch to the cell of the candidate TN base station according to the measurement report based on the cell of the candidate TN base station in the LTM switching process. If the UE or the first NTN base station determines to switch to the cell of the candidate TN base station, the cell of the candidate TN base station is accessed based on the pre-configuration information.

[0192] The above S1001-S1003 complete the pre-configuration of the candidate TN base station.

[0193] S1004: The second NTN base station sends a second handover request to the first NTN base station, where the second handover request is used to request handover from the cell of the second NTN base station to the cell of the first NTN base station.

[0194] The second handover request includes first indication information, and the first indication information is used to indicate that the transport layer information of the candidate TN base station is inherited. Optionally, the first request may include the transport layer information of the candidate TN base station.

[0195] Optionally, the second handover request may further include second indication information, where the second indication information is used to indicate that the pre-configuration information allocated by the cell of the candidate TN base station to the UE should be retained. Optionally, the first request includes the pre-configuration information of the cell of the candidate TN base station.

[0196] S1005: The first NTN base station sends a second handover confirmation message to the second NTN base station. The second handover confirmation message is used to confirm the handover from the cell of the second NTN base station to the cell of the first NTN base station or to indicate that the first NTN base station has prepared resources for the handover.

[0197] Optionally, the second handover confirmation information carries configuration information allocated by the first NTN base station to the UE.

[0198] Optionally, the second switching confirmation information includes first information, where the first information is used to indicate confirmation of inheriting the transport layer information of the candidate TN base station.

[0199] Optionally, the first information may further include fourth indication information, where the fourth indication information is used to indicate confirmation of retaining the pre-configuration information of the cell of the candidate TN base station. Based on the first information, the second NTN base station may determine that the first NTN base station inherits the transport layer information of the candidate TN base station, or determine that the first NTN base station retains the pre-configuration information of the cell of the candidate TN base station.

[0200] It should be noted that the second NTN base station and the first NTN base station can also be switched over the Xn interface. This means that information exchange between the second and first NTN base stations does not need to go through the core network. The second NTN base station and the first NTN base station can also be switched over the Ng interface. This means that information exchange between the second and first NTN base stations needs to go through the core network.

[0201] S1006: The first NTN base station establishes a data forwarding tunnel with the candidate TN base station based on the transport layer information of the candidate TN base station.

[0202] It can be understood that: the first access network device transfers data to the candidate TN base station based on the transport layer information.

[0203] S1007: The second NTN base station sends a handover command to the UE. The handover command may be used to instruct to retain the pre-configured information of the cell of the candidate TN base station.

[0204] Optionally, the handover command carries configuration information allocated by the first NTN base station to the UE.

[0205] Optionally, after the UE switches from the cell of the second NTN base station to the cell of the first NTN, it retains the pre-configuration information of the cell of the candidate TN base station. If the pre-configuration information is based on conditional handover (CHO), the UE independently evaluates whether the cell of the candidate TN base station meets the CHO handover triggering condition. If a candidate TN base station meets the CHO handover triggering condition, it switches from the cell of the first NTN base station to the cell of the candidate TN base station that meets the CHO handover triggering condition. If the pre-configuration information is based on LTM, the first NTN base station determines whether to switch to the cell of the candidate TN base station based on the measurement report of the cell of the candidate access network base station, and the UE waits for the handover instruction from the first NTN base station.

[0206] As shown in FIG11 , FIG11 is a flow chart of another communication method provided in an embodiment of the present application. In this embodiment of the present application, the NTN base station and the candidate TN base station are switched via the Ng interface. The main steps include:

[0207] S1101: A second NTN base station sends a first handover request to a core network, where the first handover request is used to request handover from a cell of the second NTN base station to a cell of a candidate TN base station.

[0208] S1102: The core network sends a second handover request to the candidate TN base station, where the second handover request is used to request handover from the cell of the second NTN base station to the cell of the candidate TN base station.

[0209] S1103 , the candidate TN base station sends first handover confirmation information to the core network, where the first handover confirmation information includes transport layer information of the candidate TN base station and pre-configuration information of the cell of the candidate TN base station.

[0210] S1104: The core network sends second handover confirmation information to the second NTN base station. The second handover confirmation information includes transport layer information on the core network side and pre-configuration information of the cell of the candidate TN base station.

[0211] In the above S1101 - S1104 , the second NTN base station may apply for the transport layer information on the core network side and the pre-configured information of the cell of the candidate TN base station through the CHO handover process or the LTM handover process.

[0212] S1105: The second NTN base station sends pre-configuration information of the cell of the candidate TN base station to the UE.

[0213] The pre-configuration information includes pre-configuration information based on conditional switching CHO and / or pre-configuration information based on LTM switching. That is, the second NTN base station can apply for the pre-configuration information of the cell of the candidate TN base station through the CHO switching process or the LTM switching process, and send the pre-configuration information of the cell of the candidate TN base station to the UE and the first NTN base station. The UE can self-evaluate the CHO switching trigger condition of the cell of the candidate TN base station in the CHO switching process to determine whether to access the cell of the candidate TN base station. Alternatively, the first NTN base station determines whether to switch to the cell of the candidate TN base station according to the measurement report based on the cell of the candidate TN base station in the LTM switching process. If the UE or the first NTN base station determines to switch to the cell of the candidate TN base station, the cell of the candidate TN base station is accessed based on the pre-configuration information.

[0214] The above S1101 - S1105 complete the pre-configuration of the candidate TN base station.

[0215] S1106: The second NTN base station sends a third handover request to the first NTN base station, where the third handover request is used to request handover from the cell of the second NTN base station to the cell of the first NTN base station.

[0216] The third handover request includes first indication information, and the first indication information is used to indicate inheritance of the transport layer information on the core network side. Optionally, the first request may include the transport layer information on the core network side.

[0217] Optionally, the third handover request may further include second indication information, where the second indication information is used to indicate that the pre-configuration information allocated by the cell of the candidate TN base station to the UE should be retained. Optionally, the first request includes the pre-configuration information of the cell of the candidate TN base station.

[0218] S1107: The first NTN base station sends third handover confirmation information to the second NTN base station. The third handover confirmation information is used to confirm handover from the cell of the second NTN base station to the cell of the first NTN base station, or to indicate that the first NTN base station has prepared resources for handover.

[0219] Optionally, the third handover confirmation information carries configuration information allocated by the first NTN base station to the UE.

[0220] Optionally, the third switching confirmation information includes first information, where the first information is used to indicate confirmation of inheriting the transport layer information on the core network side.

[0221] Optionally, the first information may further include fourth indication information, where the fourth indication information is used to indicate confirmation of retaining the pre-configuration information of the cell of the candidate TN base station. Based on the first information, the second NTN base station may determine that the first NTN base station inherits the transport layer information on the core network side, or determine that the first NTN base station retains the pre-configuration information of the cell of the candidate TN base station.

[0222] It should be noted that the second NTN base station can be switched to the first NTN base station via the Xn interface. This means that information exchange between the second and first NTN base stations does not need to go through the core network. The second and first NTN base stations can also be switched to the Ng interface. This means that information exchange between the second and first NTN base stations needs to go through the core network.

[0223] S1108: The first NTN base station establishes a data forwarding tunnel with the candidate TN base station based on the transport layer information of the core network.

[0224] It can be understood that: the first access network device transfers data to the candidate TN base station based on the transport layer information.

[0225] Specifically, the data forwarding tunnel includes a first data forwarding tunnel and a second data forwarding tunnel. The first NTN base station establishes the first data forwarding tunnel with the core network based on the transport layer information on the core network side in S1106. The core network establishes the second data forwarding tunnel with the cell of the candidate TN base station based on the transport layer information of the candidate TN base station in S1103.

[0226] S1109: The second NTN base station sends a handover command to the UE. The handover command may be used to instruct to retain the pre-configured information of the cell of the candidate TN base station.

[0227] Optionally, the handover command carries configuration information allocated by the first NTN base station to the UE.

[0228] Optionally, after the UE switches from the cell of the second NTN base station to the cell of the first NTN, it retains the pre-configuration information for the cell of the candidate TN base station. If the pre-configuration information is based on conditional handover (CHO), the UE independently evaluates whether the cell of the candidate TN base station meets the CHO handover triggering conditions. If a candidate TN base station meets the CHO handover triggering conditions, it switches from the cell of the first NTN base station to the cell of the candidate TN base station that meets the CHO handover triggering conditions. If the pre-configuration information is based on LTM, the first NTN base station determines whether to switch to the cell of the candidate TN base station based on the measurement report of the cell of the candidate access network base station. The UE waits for the handover instruction from the first NTN base station.

[0229] The embodiments shown in Figures 10 and 11 are examples of the embodiment shown in Figure 9. The specific implementation of the embodiments shown in Figures 10 and 11 can refer to the specific implementation of the embodiment shown in Figure 9, and will not be repeated here.

[0230] It can be understood that in the above-mentioned method embodiments, the methods and operations implemented by the terminal device can also be implemented by components that can be used for the terminal device (such as chips or circuits), and the methods and operations implemented by the access network device can also be implemented by components that can be used for the access network device (such as chips or circuits).

[0231] In the embodiment of the present application, the functional modules of the terminal device or access network device can be divided according to the above method example. For example, each functional module can be divided according to each function, or two or more functions can be integrated into one processing module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical functional division. There may be other division methods in actual implementation. The following is an example of dividing each functional module according to each function.

[0232] The method provided in the embodiment of the present application is described in detail above in conjunction with Figures 9-11. Below, the communication device provided in the embodiment of the present application is described in detail in conjunction with Figure 12. It should be understood that the description of the device embodiment corresponds to the description of the method embodiment. Therefore, for matters not described in detail, please refer to the method embodiment above. For the sake of brevity, it will not be repeated here.

[0233] 12 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application. The communication device may include a receiving module 1201, a processing module 1202, and a sending module 1203.

[0234] Optionally, the communication device may implement steps or processes corresponding to those performed by the access network device in the above method embodiments. For example, the communication device may be an access network device, or a chip or circuit configured in the access network device. The receiving module 1201 and the sending module 1203 are used to perform the transmission and reception related operations on the access network device side in the above method embodiments, and the processing module 1202 is used to perform the processing related operations of the access network device in the above method embodiments.

[0235] In one embodiment:

[0236] A receiving module 1201 is configured to receive a first request sent by a second access network device, where the first request is used to request handover from a cell of the second access network device to a cell of the first access network device, and the first request includes first indication information, where the first indication information is used to indicate inheritance of transport layer information for data transfer to a candidate access network device;

[0237] The processing module 1202 is configured to establish a data forwarding tunnel with the candidate access network device based on the transport layer information.

[0238] Optionally, the first request includes the transport layer information.

[0239] Optionally, the first request also includes second indication information, where the second indication information is used to indicate that pre-configuration information of the cell of the candidate access network device is retained, and the pre-configuration information is used to access the cell of the candidate access network device.

[0240] Optionally, the first request includes the pre-configuration information.

[0241] Optionally, the pre-configuration information includes pre-configuration information based on conditional handover (CHO) and / or pre-configuration information based on L1 / L2 triggered mobility (LTM) handover.

[0242] Optionally, the sending module 1203 is used to send first information to the second access network device, where the first information is used to indicate confirmation of inheriting the transport layer information for data transfer to the candidate access network device.

[0243] Optionally, the transport layer information includes transport layer information on the core network side.

[0244] Optionally, the transport layer information includes transport layer information on the candidate access network device side.

[0245] Optionally, the first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is an NT base station, and the candidate access network device is an NTN base station.

[0246] In another embodiment:

[0247] Receiving module 1201, used to obtain transport layer information for transferring data to a candidate access network device;

[0248] The sending module 1203 is used to send a first request to the first access network device, where the first request is used to request switching from the cell of the second access network device to the cell of the first access network device. The first request includes first indication information, and the first indication information is used to indicate the inheritance of transport layer information for data transfer to the candidate access network device.

[0249] Optionally, the first request includes the transport layer information.

[0250] Optionally, the first request also includes second indication information, where the second indication information is used to indicate that pre-configuration information of the cell of the candidate access network device is retained, and the pre-configuration information is used to access the cell of the candidate access network device.

[0251] Optionally, the first request includes the pre-configuration information.

[0252] Optionally, the pre-configuration information includes pre-configuration information based on conditional handover (CHO) and / or pre-configuration information based on L1 / L2 triggered mobility (LTM) handover.

[0253] Optionally, the receiving module 1201 is further used to receive first information sent by the first access network device, where the first information is used to indicate confirmation of inheriting the transport layer information for data transfer to the candidate access network device.

[0254] Optionally, the sending module 1203 is also used to send second information to the terminal device, where the second information is used to indicate switching from the cell of the second access network device to the cell of the first access network device, and the second information includes third indication information, where the third indication information is used to indicate retaining the pre-configuration information of the cell of the candidate access network device.

[0255] Optionally, the sending module 1203 is further used to send pre-configuration information of the cell of the candidate access network device to the second access network device and the terminal device.

[0256] Optionally, the transport layer information includes address information on the core network side.

[0257] Optionally, the transport layer information includes transport layer information on the candidate access network device side.

[0258] Optionally, the first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is an NT base station, and the candidate access network device is an NTN base station.

[0259] It should be noted that the implementation of each module can also correspond to the corresponding description of the method embodiments shown in Figures 9 to 11, and execute the methods and functions executed by the first access network device and the second access network device in the above embodiments.

[0260] FIG13 is a schematic diagram of the structure of an access network device provided in an embodiment of the present application. The access network device can be applied to the system shown in FIG1 to FIG4 to perform the functions of the first access network device and the second access network device in the above method embodiment, or to implement the steps or processes performed by the first access network device and the second access network device in the above method embodiment.

[0261] As shown in Figure 13, the access network device includes a processor 1301 and a transceiver 1302. Optionally, the access network device also includes a memory 1303. The processor 1301, transceiver 1302, and memory 1303 can communicate with each other via internal connection paths to transmit control and / or data signals. The memory 1303 is used to store computer programs, and the processor 1301 is used to retrieve and execute the computer programs from the memory 1303 to control the transceiver 1302 to transmit and receive signals. Optionally, the access network device may also include an antenna for transmitting uplink data or uplink control signaling output by the transceiver 1302 via wireless signals.

[0262] The processor 1301 and the memory 1303 may be combined into a processing device, and the processor 1301 is configured to execute program code stored in the memory 1303 to implement the aforementioned functions. In a specific implementation, the memory 1303 may also be integrated into the processor 1301 or independent of the processor 1301. The processor 1301 may correspond to the processing module in FIG10 .

[0263] The transceiver 1302 may correspond to the receiving module and transmitting module in FIG10 , and may also be referred to as a transceiver unit or transceiver module. The transceiver 1302 may include a receiver (or receiver, receiving circuit) and a transmitter (or transmitter, transmitting circuit). The receiver is used to receive signals, and the transmitter is used to transmit signals.

[0264] It should be understood that the access network device shown in Figure 13 is capable of implementing the various processes related to the access network device in the method embodiments shown in Figures 9 to 11. The operations and / or functions of the various modules in the access network device are respectively for implementing the corresponding processes in the aforementioned method embodiments. For details, please refer to the description of the aforementioned method embodiments; to avoid repetition, detailed descriptions are omitted here.

[0265] The processor 1301 can be used to execute the actions implemented within the access network device described in the previous method embodiments, while the transceiver 1302 can be used to execute the actions of the access network device sending to or receiving from the access network device described in the previous method embodiments. For details, please refer to the description of the previous method embodiments and will not be repeated here.

[0266] The processor 1301 may be a central processing unit (CPU), a general-purpose processor (GPOR), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device (PLD), a transistor logic device (TLD), a hardware component, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. The processor 1301 may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and so on. The communication bus 1304 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industrial Standard Architecture (EISA) bus. These buses may be categorized as address buses, data buses, control buses, and so on. For ease of illustration, FIG13 shows only one bold line, but this does not imply that there is only one bus or type of bus. The communication bus 1304 is used to facilitate communication between these components. In the embodiment of this application, the transceiver 1302 is used to communicate signaling or data with other node devices. The memory 1303 may include volatile memory, such as nonvolatile dynamic random access memory (NVRAM), phase change random access memory (PRAM), magnetoresistive random access memory (MRAM), etc. It may also include non-volatile memory, such as at least one disk storage device, electrically erasable programmable read-only memory (EEPROM), flash memory devices, such as NOR flash memory or NAND flash memory, semiconductor devices, such as solid state disks (SSDs), etc. The memory 1303 may optionally be at least one storage device located remote from the aforementioned processor 1301. The memory 1303 may optionally also store a set of computer program code or configuration information. Optionally, the processor 1301 may also execute the program stored in the memory 1303. The processor may cooperate with the memory and the transceiver to execute any one of the methods and functions of the first access network device or the second access network device in the above-mentioned application embodiments.

[0267] An embodiment of the present application also provides a chip system, which includes a processor for supporting a terminal device or an access network device to implement the functions involved in any of the above embodiments, such as generating or processing the transport layer information involved in the above method.

[0268] In one possible design, the chip system may also include a memory for storing computer programs and data necessary for the terminal device or access network device. The chip system may consist of a single chip or may include a chip and other discrete components. The inputs and outputs of the chip system correspond to the receive and transmit operations of the terminal device or access network device in the method embodiment, respectively.

[0269] According to the method provided in the embodiments of the present application, the present application also provides a computer program product, which includes: a computer program, which, when running on a computer, enables the computer to execute the method of any one of the embodiments shown in Figures 9 to 11.

[0270] According to the method provided in the embodiments of the present application, the present application also provides a computer-readable medium, which stores a computer program. When the computer program runs on a computer, the computer executes the method of any one of the embodiments shown in Figures 9 to 11.

[0271] According to the method provided in the embodiment of the present application, the present application also provides a communication system, which includes one or more terminal devices and one or more access network devices as mentioned above.

[0272] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated therein. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a high-density digital video disc (DVD)), or a semiconductor medium (eg, a solid state disc (SSD)).

[0273] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: The method comprises: A first access network device receives a first request sent by a second access network device, where the first request is used to request switching from a cell of the second access network device to a cell of the first access network device, and the first request includes first indication information, where the first indication information is used to indicate inheritance of transport layer information for data transfer to a candidate access network device; The first access network device establishes a data forwarding tunnel with the candidate access network device based on the transport layer information.

2. The method according to claim 1, characterized in that The first request includes the transport layer information.

3. The method according to claim 1 or 2, characterized in that The first request also includes second indication information, where the second indication information is used to indicate that pre-configuration information of the cell of the candidate access network device is retained, and the pre-configuration information is used to access the cell of the candidate access network device.

4. The method according to claim 3, characterized in that The first request includes the pre-configuration information.

5. The method according to claim 3 or 4, characterized in that The pre-configuration information includes pre-configuration information based on conditional handover CHO and / or pre-configuration information based on L1 / L2 triggered mobility LTM handover.

6. The method according to any one of claims 1 to 5, characterized in that: The method comprises: The first access network device sends first information to the second access network device, where the first information is used to indicate confirmation of inheriting the transport layer information for transferring data to the candidate access network device.

7. The method according to any one of claims 1 to 6, characterized in that: The transport layer information includes the transport layer information on the core network side.

8. The method according to any one of claims 1 to 6, characterized in that: The transport layer information includes the transport layer information on the candidate access network device side.

9. The method according to any one of claims 1 to 8, characterized in that: The first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is a NT base station, and the candidate access network device is a NTN base station.

10. A communication method, characterized in that: The method comprises: The second access network device acquires transport layer information for transferring data to the candidate access network device; The second access network device sends a first request to the first access network device, where the first request is used to request switching from the cell of the second access network device to the cell of the first access network device, and the first request includes first indication information, where the first indication information is used to indicate inheritance of transport layer information for data transfer to the candidate access network device.

11. The method according to claim 10, characterized in that The first request includes the transport layer information.

12. The method according to claim 10 or 11, characterized in that The first request also includes second indication information, where the second indication information is used to indicate that pre-configuration information of the cell of the candidate access network device is retained, and the pre-configuration information is used to access the cell of the candidate access network device.

13. The method according to claim 12, characterized in that The first request includes the pre-configuration information.

14. The method according to claim 12 or 13, characterized in that The pre-configuration information includes pre-configuration information based on conditional handover CHO and / or pre-configuration information based on L1 / L2 triggered mobility LTM handover.

15. The method according to any one of claims 10 to 14, characterized in that: The method comprises: The second access network device receives first information sent by the first access network device, where the first information is used to indicate confirmation of inheriting the transport layer information for transferring data to the candidate access network device.

16. The method according to any one of claims 9 to 15, characterized in that: The method comprises: The second access network device sends second information to the terminal device, the second information is used to indicate switching from the cell of the second access network device to the cell of the first access network device, the second information includes third indication information, and the third indication information is used to indicate retaining the pre-configuration information of the cell of the candidate access network device.

17. The method according to claim 16, characterized in that The method comprises: The second access network device sends pre-configuration information of the cell of the candidate access network device to the terminal device.

18. The method according to any one of claims 10 to 17, characterized in that: The transport layer information includes address information on the core network side.

19. The method according to any one of claims 10 to 17, characterized in that: The transport layer information includes the transport layer information on the candidate access network device side.

20. The method according to any one of claims 10 to 19, characterized in that: The first access network device or the second access network device is a non-terrestrial network NTN base station, and the candidate access network device is a terrestrial network NT base station; or, the first access network device or the second access network device is a NT base station, and the candidate access network device is a NTN base station.

21. A communication device, characterized in that: The communication device comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the communication device to perform the method according to any one of claims 1 to 9.

22. A communication device, characterized in that: The communication device comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the communication device to perform the method according to any one of claims 10 to 20.

23. A communication system, characterized in that: The system includes a first access network device and a second access network device, the first access network device is used to execute the method according to any one of claims 1-9, and the second access network device is used to execute the method according to any one of claims 10-20.

24. A computer-readable storage medium, characterized in that: The computer-readable storage medium comprises a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 20 is implemented.

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