Communication method and device

Abstract

Disclosed are a communication method and device, the method being applied to a target access network device, the method comprising: receiving a first request message from a source access network device, the first request message being used for requesting configuration information of at least one candidate cell of a terminal device, the first request message comprising first information, the first information is used for indicating that the first protocol layer function is provided by the source access network device; and sending a first acknowledgement message to the source access network device, wherein the first acknowledgement message comprises first configuration information of the at least one candidate cell. In the present application, in a candidate cell pre-configuration process of LTM handover, a source access network device and a target access network device can negotiate that a first protocol layer function (e.g., a PDCP layer function) is still provided by the source access network device, that is, the first protocol layer function resides in the source access network device, and the first protocol layer function is still provided by the target access network device. According to the invention, the terminal device does not reestablish the function of the first protocol layer in the LTM switching process, so that the switching interruption time is reduced.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0002] During L1 and / or L2 layer-triggered mobility (LTM) handover, terminal devices may need to reset the L2 protocol stack, which could result in handover interruption time.

[0003] Currently, L2 protocol stack reset includes the re-establishment of radio link control (RLC) layer functions, medium access control (MAC) layer functions, and packet data convergence protocol (PDCP) layer functions. Since the PDCP layer function re-establishment process involves changing encryption and integrity protection key information, it introduces additional handover interruption time. Therefore, how to reduce handover interruption time and improve service experience during LTM handover is worth studying. Summary of the Invention

[0004] This application provides a communication method and apparatus for reducing handover interruption time.

[0005] In a first aspect, embodiments of this application provide a communication method applicable to a target access network device, which may be, for example, a target access network equipment, or other equipment including the functions of a target access network equipment, or a chip system (or chip) or other functional module capable of implementing the functions of the target access network equipment, and which may be disposed, for example, in the target access network equipment. The method includes: receiving a first request message from a source access network device, wherein the first request message is used to request configuration information of at least one candidate cell of a terminal device, the first request message including first information indicating that a first protocol layer function is provided by the source access network device; and sending a first confirmation message to the source access network device, wherein the first confirmation message includes the first configuration information of the at least one candidate cell.

[0006] In the embodiments of this application, during the pre-configuration of candidate cells for LTM handover, the source access network device and the target access network device can negotiate that the first protocol layer function (e.g., PDCP layer function) is still provided by the source access network device. That is, the first protocol layer function resides in the source access network device, so that the terminal device does not re-establish the first protocol layer function during LTM handover, thereby reducing the handover interruption time.

[0007] In one possible implementation, the first request message further includes information about a first radio bearer to be established, wherein the information about the first radio bearer to be established is used to generate the first configuration information, and the first configuration information is configuration information related to the second protocol layer function.

[0008] In this embodiment, since the first protocol layer function includes transmitting different services using different radio bearers, the source access network device can determine the information of the first radio bearer to be established and send it to the target access network device. This allows the target access network device to generate configuration information related to the second protocol layer function based on the information of the first radio bearer to be established, without generating configuration information related to the first protocol layer function. Thus, the first protocol layer function is provided by the source access network device.

[0009] In one possible implementation, the second protocol layer function includes one or more of RLC layer functions, MAC layer functions, and PHY layer functions. This implementation provides multiple implementations of the second protocol layer function, such as RLC layer functions, MAC layer functions, and PHY layer functions.

[0010] In one possible implementation, the information of the first radio bearer to be established includes one or more of the following: the quality of service (QoS) information of the first radio bearer to be established; the tunnel information of the first radio bearer to be established; and the identification information of the first radio bearer to be established.

[0011] In this embodiment, multiple implementations of the information of the first radio bearer to be established are provided, making the way in which the source access network device indicates the information of the first radio bearer to be established more flexible, and correspondingly, the way in which the target access network device determines the information of the first radio bearer to be established is also more flexible.

[0012] In one possible implementation, the first confirmation message further includes information about an established first radio bearer, wherein the information about the established first radio bearer is used to generate second configuration information for the at least one candidate cell, and the second configuration information is configuration information related to the first protocol layer function.

[0013] In this embodiment, since the first protocol layer function includes transmitting different services using different radio bearers, the target access network device can determine the information of the established first radio bearer and send it to the source access network device. The source access network device can generate configuration information related to the first protocol layer function based on the information of the established first radio bearer, so that the first protocol layer function is provided by the source access network device.

[0014] In one possible implementation, the first protocol layer function includes one or more of the following: radio resource control (RRC) layer function, service data adaptation protocol (SDAP) layer function, and PDCP layer function. This implementation provides multiple implementations of the first protocol layer function, such as RRC layer function, SDAP layer function, and PDCP layer function.

[0015] In one possible implementation, the first request message may further include: configuration information preferred by the terminal device; and / or, RRC version information of the source access network device.

[0016] In this embodiment, the target access network device can generate configuration information suitable for the terminal device related to the second protocol layer function based on the terminal device's preferred configuration information (e.g., discontinuous reception (DRX) period). Alternatively, the target access network device can also generate configuration information suitable for the source access network device related to the second protocol layer function based on the source access network device's RRC version information. For example, if the source access network device's RRC version is incompatible with the RRC parameters corresponding to the functions supported by the target access network device, and the source access network device cannot generate configuration information related to some communication functions, then even if the target access network device supports these communication functions, the target access network device does not need to generate configuration information related to the second protocol layer function when generating configuration information related to these communication functions.

[0017] In one possible implementation, the method further includes: sending second information to the source access network device, wherein the second information includes information about neighboring cells of the cell managed by the target access network device, the second information being used to generate second configuration information for the at least one candidate cell, and the second configuration information being configuration information related to the first protocol layer function.

[0018] In this embodiment, since the configuration information related to the first protocol layer function includes configuration information related to neighbor cell measurement, the target access network device can determine the information of the neighbor cells of the cell managed by the target access network device and send it to the source access network device. The source access network device can generate configuration information related to the first protocol layer function based on the information of the neighbor cells of the cell managed by the target access network device, so that the first protocol layer function is provided by the source access network device.

[0019] In one possible implementation, the target access network device is a target central unit (CU); the method further includes: the target CU sending a second request message to the target distributed unit (DU), wherein the target DU is used to provide the at least one candidate cell, the second request message including: the first information; and / or, information of a first radio bearer to be established, the information of the first radio bearer to be established being used to generate the first configuration information, the first configuration information being configuration information related to a second protocol layer function; the target CU receiving a second confirmation message from the target DU, wherein the second confirmation message includes: the first configuration information; and / or, information of an established first radio bearer, the information of the established first radio bearer being used to generate second configuration information of the at least one candidate cell, the second configuration information being configuration information related to the first protocol layer function.

[0020] In this embodiment, if the target access network device is a target CU, the target CU can send the information of the first radio bearer to be established, determined by the source CU, to the target DU, so that the target CU can generate configuration information related to the second protocol layer function based on the information of the first radio bearer to be established. That is to say, the target CU does not need to generate configuration information related to the second protocol layer function, nor does it need to generate configuration information related to the first protocol layer function; it only acts as a relay device between the source access network device and the target DU, so that the first protocol layer function is provided by the source access network device.

[0021] In one possible implementation, the method further includes: receiving a third request message from the source access network device, wherein the third request message is used to indicate that the first protocol layer function is provided by the target access network device; and sending a third confirmation message to the source access network device, wherein the third confirmation message includes third configuration information and fourth configuration information of the at least one candidate cell, the third configuration information being configuration information related to the second protocol layer function, and the fourth configuration information being configuration information related to the first protocol layer function.

[0022] In this embodiment, after the terminal device performs LTM handover, if the source access network device is the source CU and the target access network device is the target CU, the source CU can switch the first protocol layer function from being provided by the source CU to being provided by the target CU, thereby reducing the load on the source CU or the latency between the source CU and the target CU.

[0023] In one possible implementation, the method further includes: sending a first indication message to the source access network device; wherein the first indication message is used to indicate that the first protocol layer function is provided by the target access network device, the first indication message includes third configuration information and fourth configuration information of the at least one candidate cell, the third configuration information being configuration information related to the second protocol layer function, and the fourth configuration information being configuration information related to the first protocol layer function.

[0024] In this embodiment, after the terminal device performs LTM handover, if the source access network device is the source CU and the target access network device is the target CU, the target CU can switch the first protocol layer function from being provided by the source access network device to being provided by the target access network device. Since the source CU is unaware of the specific resource situation of the target DU, while the target CU is aware of the specific resource situation of the target DU, the resource utilization rate of the target DU is improved.

[0025] In one possible implementation, the target access network device is a target CU; the method further includes: receiving a second indication message from the target DU, wherein the target DU is used to provide the at least one candidate cell, and the second indication message is used to indicate that the first protocol layer function is provided by the target CU.

[0026] In this embodiment, after the terminal device performs LTM handover, if the source access network device is the source CU and the target access network device is the target CU, the target DU can switch the first protocol layer function from being provided by the source CU to being provided by the target CU, thereby reducing the load on the source CU or the latency between the source CU and the target DU.

[0027] In one possible implementation, the target access network device is a target CU; the method further includes: sending a fourth request message to the target DU, wherein the target DU is used to provide the at least one candidate cell, the fourth request message including: third information, the third information being used to indicate that the first protocol layer function is provided by the target access network device; and / or, information of a second radio bearer to be established, the information of the second radio bearer to be established being used to generate the third configuration information; receiving a fourth confirmation message from the target DU, wherein the fourth confirmation message includes the third configuration information, and / or, information of an established second radio bearer, the information of the established second radio bearer being used to generate the fourth configuration information.

[0028] In this embodiment, if the target access network device is a target CU, the target CU can determine the information of the second radio bearer to be established and send it to the target DU, so that the target CU can generate configuration information related to the second protocol layer function based on the information of the second radio bearer to be established. That is, the target CU needs to generate configuration information related to the first protocol layer function so that the first protocol layer function is provided by the target access network device.

[0029] In one possible implementation, the target access network device is a target CU; the method further includes: receiving fourth information from the source access network device, wherein the target DU is used to provide the at least one candidate cell, the fourth information is obtained by encrypting and protecting the third configuration information and the fourth configuration information according to a first key, the first key corresponding to the source access network device; and sending the fourth information to the target DU.

[0030] In this embodiment, if the target access network device is the target CU, since the terminal device only has the key of the source access network device and not the key of the target CU, the source access network device can only use the key of the source CU to encrypt and protect the integrity of the third configuration information and the fourth configuration information of at least one candidate cell of the terminal device to obtain the fourth information, which is then sent to the terminal device via the target CU and the target DU.

[0031] In one possible implementation, the method further includes: receiving fifth information and first data from the target DU, wherein the fifth information is used to indicate that the terminal device has accessed a first candidate cell among the at least one candidate cell, and the first data is obtained by encrypting and protecting the integrity of second data according to a second key, the second key corresponding to the first candidate cell.

[0032] In this embodiment, if the target access network device is the target CU, since the key of the target CU may include the key corresponding to at least one candidate cell of the terminal device, and the keys corresponding to different candidate cells are different, if the terminal device has accessed the first candidate cell among at least one candidate cell of the terminal device and has completed the first protocol layer function re-establishment, the terminal device can use the key corresponding to the first candidate cell to encrypt and protect the integrity of the second data, obtain the first data, and send it to the target CU via the target DU, so that the target CU can use the key corresponding to the first candidate cell to decrypt the first data and obtain the second data, thereby determining that the terminal device has completed the first protocol layer function re-establishment.

[0033] In one possible implementation, the method further includes: sending a fifth request message to a core network device, wherein the fifth request message is used to request the core network device to switch the endpoint of the downlink user plane tunnel from the source access network device to the target CU.

[0034] In this embodiment, if the target access network device is the target CU, then when the target CU determines that the terminal device has successfully applied the third configuration information and fourth configuration information of at least one candidate cell of the terminal device, the target CU can request the core network device to switch the endpoint of the downlink user plane tunnel from the source access network device to the target CU, thereby completing the switch of the first protocol layer function from the source CU to the target CU.

[0035] Secondly, embodiments of this application also provide a communication method, which can be applied to a source access network device, such as a source access network equipment, or other devices including source access network equipment functions, or a chip system (or chip) or other functional module, which can implement the functions of the source access network equipment, and is, for example, disposed in the source access network equipment. The method includes: sending a first request message to a target access network device, wherein the first request message is used to request configuration information of at least one candidate cell of a terminal device, the first request message including first information, the first information being used to indicate that a first protocol layer function is provided by the source access network device; and receiving a first confirmation message from the target access network device, wherein the first confirmation message includes the first configuration information of the at least one candidate cell.

[0036] In one possible implementation, the first request message further includes information about a first radio bearer to be established, wherein the information about the first radio bearer to be established is used to generate the first configuration information, and the first configuration information is configuration information related to the second protocol layer function.

[0037] In one possible implementation, the second protocol layer function includes one or more of the RLC layer function, MAC layer function, and PHY layer function.

[0038] In one possible implementation, the information of the first radio bearer to be established includes one or more of the following: QoS information of the first radio bearer to be established; tunnel information of the first radio bearer to be established; and identification information of the first radio bearer to be established.

[0039] In one possible implementation, the first confirmation message further includes information about an established first radio bearer, wherein the information about the established first radio bearer is used to generate second configuration information for the at least one candidate cell, and the second configuration information is configuration information related to the first protocol layer function.

[0040] In one possible implementation, the first protocol layer function includes one or more of the following: RRC layer function, SDAP layer function, and PDCP layer function.

[0041] In one possible implementation, the first request message may further include: configuration information preferred by the terminal device; and / or, RRC version information of the source access network device.

[0042] In one possible implementation, the method further includes: receiving second information from the target access network device, wherein the second information includes information about neighboring cells of the cell managed by the target access network device, the second information being used to generate second configuration information for the at least one candidate cell, and the second configuration information being configuration information related to the first protocol layer function.

[0043] In one possible implementation, the method further includes: sending the first configuration information to the terminal device, the first configuration information being used to indicate that the first protocol layer function is provided by the source access network device; or, sending the first configuration information and second configuration information of the at least one candidate cell to the terminal device, wherein the second configuration information is configuration information related to the first protocol layer function, and the second configuration information is used to indicate that the first protocol layer function is provided by the source access network device.

[0044] In one possible implementation, the method further includes: sending a third request message to a target access network device, wherein the third request message is used to indicate that the first protocol layer function is provided by the target access network device; receiving a third confirmation message from the target access network device, wherein the third confirmation message includes third configuration information and fourth configuration information of the at least one candidate cell, the third configuration information being configuration information related to the second protocol layer function, and the fourth configuration information being configuration information related to the first protocol layer function.

[0045] In one possible implementation, the method further includes: receiving a first indication message from the target access network device; wherein the first indication message is used to indicate that the first protocol layer function is provided by the target access network device, the first indication message includes third configuration information and fourth configuration information of the at least one candidate cell, the third configuration information being configuration information related to the second protocol layer function, and the fourth configuration information being configuration information related to the first protocol layer function.

[0046] In one possible implementation, the method further includes: sending fourth information to the target access network device, wherein the fourth information is obtained by encrypting and protecting the third configuration information and the fourth configuration information according to a first key, and the first key corresponds to the source access network device.

[0047] The beneficial effects of the second aspect and its implementation can be referred to the beneficial effects of the first aspect and any of its implementations.

[0048] Thirdly, embodiments of this application also provide a communication device. The communication device can be the source access network device described in the first aspect above. The communication device possesses the functions of the aforementioned source access network device. This communication device is, for example, a source access network equipment, or other equipment including the functions of a source access network equipment, or a chip system (or chip) or other functional module, which can implement the functions of the source access network equipment, and is, for example, disposed within the source access network equipment. In one optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also called a processing module) and a transceiver unit (sometimes also called a transceiver module). The transceiver unit can implement both transmitting and receiving functions. When the transceiver unit implements the transmitting function, it can be called a transmitting unit (sometimes also called a transmitting module), and when the transceiver unit implements the receiving function, it can be called a receiving unit (sometimes also called a receiving module). The transmitting unit and the receiving unit can be the same functional module, which is called the transceiver unit. This functional module can realize the transmitting and receiving functions; or, the transmitting unit and the receiving unit can be different functional modules, and the transceiver unit is a general term for these functional modules.

[0049] In one optional implementation, the transceiver unit is configured to receive a first request message from a source access network device, wherein the first request message is used to request configuration information of at least one candidate cell of the terminal device, the first request message including first information, the first information being used to indicate that a first protocol layer function is provided by the source access network device; and to send a first confirmation message to the source access network device, wherein the first confirmation message includes the first configuration information of the at least one candidate cell.

[0050] Fourthly, embodiments of this application also provide a communication device. The communication device can be the target access network device described in the second aspect above. The communication device possesses the functions of the target access network device. This communication device is, for example, a target access network equipment, or other equipment including the functions of a target access network equipment, or a chip system (or chip) or other functional module, which can implement the functions of the target access network equipment, and is, for example, disposed within the target access network equipment. In one optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also called a processing module) and a transceiver unit (sometimes also called a transceiver module). The transceiver unit can implement both transmitting and receiving functions. When the transceiver unit implements the transmitting function, it can be called a transmitting unit (sometimes also called a transmitting module), and when the transceiver unit implements the receiving function, it can be called a receiving unit (sometimes also called a receiving module). The transmitting unit and the receiving unit can be the same functional module, which is called the transceiver unit. This functional module can realize the transmitting and receiving functions; or, the transmitting unit and the receiving unit can be different functional modules, and the transceiver unit is a general term for these functional modules.

[0051] In one optional implementation, the transceiver unit is configured to send a first request message to a target access network device, wherein the first request message is used to request configuration information of at least one candidate cell of the terminal device, the first request message includes first information, the first information being used to indicate that a first protocol layer function is provided by the source access network device; and to receive a first confirmation message from the target access network device, wherein the first confirmation message includes the first configuration information of the at least one candidate cell.

[0052] Fifthly, a communication device is provided, which can be the source access network device described in the first aspect above. The communication device possesses the functions of the source access network device described above. The communication device is, for example, a source access network equipment, or other equipment including the functions of a source access network equipment, or a system-on-a-chip (or chip) or other functional module capable of implementing the functions of the source access network equipment, and the system-on-a-chip or functional module is, for example, disposed within the source access network equipment. The communication device includes a processor for executing the functions of the source access network device described in the first aspect above. Optionally, the communication device further includes a memory. The memory stores a computer program, and the processor is coupled to the memory. When the processor reads the computer program or instructions, it causes the communication device to execute the methods performed by the source access network device in the above aspects.

[0053] Sixthly, a communication device is provided, which can be the target access network device described in the second aspect above. The communication device possesses the functions of the target access network device. The communication device is, for example, a target access network equipment, or other equipment including the functions of a target access network equipment, or a system-on-a-chip (or chip) or other functional module capable of implementing the functions of the target access network equipment, and the system-on-a-chip or functional module is, for example, disposed within the target access network equipment. The communication device includes a processor for executing the functions of the target access network device described in the second aspect above. Optionally, the communication device further includes a memory. The memory stores a computer program, and the processor is coupled to the memory. When the processor reads the computer program or instructions, it causes the communication device to execute the methods performed by the target access network device in the above aspects.

[0054] A seventh aspect provides a communication system including a source access network device. This source access network device is used to perform the method described in the first aspect. For example, the source access network device can be implemented using the communication device described in the third or fifth aspect.

[0055] Optionally, the communication system further includes a target access network device. This target access network device is used to perform the method described in the second aspect above. For example, the target access network device can be implemented using the communication device described in the fourth or sixth aspect.

[0056] Eighthly, a computer-readable storage medium is provided for storing a computer program or instructions that, when executed, cause the methods performed by the source access network device or the target access network device in the above aspects to be implemented.

[0057] Ninthly, a computer program product containing instructions is provided, which, when the computer program or instructions are run on a computer, causes the methods described in the above aspects to be implemented.

[0058] In a tenth aspect, a chip system is provided, including a processor and an interface, the processor being configured to call and execute instructions from the interface to enable the chip system to implement the methods described above. Attached Figure Description

[0059] Figure 1 This application provides a schematic diagram of the structure of a communication system according to an embodiment of the present application.

[0060] Figure 2 A schematic diagram of a CU-DU separation architecture used in an access network device according to an embodiment of this application;

[0061] Figure 3 A schematic diagram of a 5G wireless communication system provided in an embodiment of this application;

[0062] Figure 4a A schematic diagram of an LTM switching scenario provided for the example of this application;

[0063] Figure 4b A schematic diagram of an LTM switching process provided for the example of this application;

[0064] Figure 4c A schematic diagram illustrating another LTM switching scenario provided for this application example;

[0065] Figure 4d A schematic diagram illustrating another LTM switching scenario provided for this application example;

[0066] Figure 5 A flowchart illustrating a communication method provided in an embodiment of this application;

[0067] Figure 6 A flowchart illustrating another communication method provided in an embodiment of this application;

[0068] Figure 7 A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0069] Figure 8 A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0070] Figure 9 A flowchart illustrating yet another communication method provided in an embodiment of this application;

[0071] Figure 10 A schematic diagram of a communication device provided in an embodiment of this application;

[0072] Figure 11 This is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0073] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0074] The technical solutions of this application can be applied to various communication systems, such as: Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access (CDMA), Wireless Local Area Network (WLAN), Sidelink Communication System, 4th Generation (4G) Communication System, 5th Generation (5G) Wireless Communication System, other future evolution systems, or other wireless communication systems employing wireless access technologies. The technical solutions of this application can be used wherever cell handover is required in the communication system.

[0075] See Figure 1 This is a schematic diagram of the structure of a communication system provided in an embodiment of this application. Figure 1 As shown, the communication system includes terminal equipment and access network equipment.

[0076] Terminal equipment, also known as user equipment (UE), mobile station (MS), or mobile terminal (MT), refers to devices that provide voice and / or data connectivity to users. For example, terminal equipment can be handheld devices with wireless connectivity, in-vehicle devices, etc. Currently, some examples of terminal equipment include: mobile phones, tablets, laptops, PDAs, mobile internet devices (MID), 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, wireless terminals in smart homes, and cellular internet of things (CIoT) devices.

[0077] In this application embodiment, the device for implementing the functions of the terminal device can be the terminal device itself; it can also be a device capable of supporting the terminal device in implementing the functions, such as a chip system, which can be installed in the terminal device. In this application embodiment, the chip system can be composed of chips, or it can include chips and other discrete devices. In the technical solutions provided in this application embodiment, the terminal device is used as an example to describe the technical solutions provided in this application embodiment.

[0078] Access network equipment can refer to radio access network (RAN) nodes (or devices) that connect terminal devices to the wireless network, such as base stations. Examples of RAN nodes include: evolved Node B (gNB), transmission reception point (TRP), evolved Node B (eNB), radio network controller (RNC), Node B (NB), base station controller (BSC), base transceiver station (BTS), home base station (e.g., home evolved Node B, or home Node B, HNB), base band unit (BBU), or wireless fidelity (Wi-Fi) access point (AP), etc.

[0079] In another network architecture, access network equipment may include centralized unit (CU) nodes, distributed unit (DU) nodes, or both CU and DU nodes. That is, access network equipment can adopt a CU-DU separation architecture, which can also be called a distributed deployment architecture. Here, the CU node performs the functions of the radio resource control (RRC) protocol and packet data convergence protocol (PDCP) of the access network equipment, and can also perform the functions of the service data adaptation protocol (SDAP). The DU node performs the functions of the radio link control (RLC) layer and medium access control (MAC) layer of the access network equipment, and can also perform some or all of the physical (PHY) layer functions. For detailed descriptions of the above protocol layers, please refer to the relevant technical specifications of the 3rd Generation Partnership Project (3GPP).

[0080] For example, see Figure 2 This is a schematic diagram of a CU-DU separation architecture used in an access network device according to an embodiment of this application. Figure 2 As shown, an access network device can logically include one CU and one or more DUs. Each DU can be connected to the CU via an F1 interface, and information exchange between different DUs can be completed based on forwarding by the CU. The CU and DU can be physically set together or physically separated, without limitation. The CU can support the functions of RRC layer protocols, PDCP layer protocols, and SDAP layer protocols; the DU can support the functions of RLC layer protocols, MAC layer protocols, and PHY layer protocols.

[0081] In this application embodiment, the apparatus for implementing the functions of the access network device can be the access network device itself; it can also be an apparatus capable of supporting the access network device in implementing the functions, such as a chip system, which can be installed in the access network device. In this application embodiment, the chip system can be composed of chips, or it can include chips and other discrete devices. In the technical solutions provided in this application embodiment, the use of an access network device as an example to describe the technical solutions provided in this application embodiment is exemplified by the use of an access network device as an apparatus for implementing the functions of the access network device.

[0082] In this embodiment, communication between the terminal device and the access network device refers to the terminal device sending uplink signals or uplink information to the access network device, with the uplink information carried on the uplink channel, and / or the access network device sending downlink signals or downlink information to the terminal device, with the downlink information carried on the downlink channel. For the terminal device to communicate with the access network device, it needs to establish a radio connection with a cell controlled by the access network device (i.e., the terminal device camps on a cell controlled by the access network device). The cell with which the terminal device establishes a radio connection is called the serving cell of the terminal device (i.e., the cell that provides service to the terminal device).

[0083] The terminal device can be located within the coverage area of ​​one or more cells (carriers), and there can be one or more cells providing service to the terminal device. For example, Figure 1 In the scenario shown, the terminal device is simultaneously located within the coverage area of ​​cell 1 controlled by access network device 1, cell 2 controlled by access network device 2, and cell 3 controlled by access network device 3. Cells 1, 2, and 3 can all provide services to the terminal device. It should be noted that... Figure 1 Taking the example of an access network device controlling only one cell, in practical applications, an access network device can control multiple cells simultaneously. When there are multiple cells providing services to a terminal device, the terminal device can operate in one or more of the following modes: carrier aggregation (CA), dual connectivity (DC), or coordinated multiple points transmission / reception (CoMP). One or more cells can provide the terminal device with radio resources corresponding to more than one set of transmission parameters.

[0084] Due to changes in terminal device mobility and / or cell channel conditions, terminal devices can switch serving cells. The serving cell where the terminal device originally camped (or the cell where the terminal device disconnected its radio connection, or the cell the terminal device switched out of) is called the source cell, and the cell where the terminal device newly camped (or the cell where the terminal device newly established a radio connection, or the cell the terminal device switched into) is called the target cell. In other words, switching serving cells means the terminal device switches from the source cell to the target cell. A terminal device can camp on only one cell or simultaneously on multiple cells. Multiple cells can be controlled by the same access network device or by different access network devices; this application embodiment does not impose any restrictions. Correspondingly, when performing a serving cell handover, the terminal device can switch to only one serving cell or simultaneously switch to multiple serving cells; this application embodiment does not limit this either.

[0085] Furthermore, communication between a cell and a terminal device (e.g., a cell sending downlink signals to a terminal device, and / or a cell receiving uplink signals from a terminal device) refers to communication between the access network equipment to which the cell belongs (e.g., the base station controlling the cell) and the terminal device. Communication between cells, such as communication between one cell and another, refers to communication between the access network equipment to which the first cell belongs and the access network equipment to which the second cell belongs (e.g., two access network equipment transmitting messages) if the two cells belong to the same access network equipment (e.g., two cells controlled by the same base station). If the two cells belong to the same access network equipment, it refers to signaling or data exchange between the functional modules controlling the first cell and the second cell within the access network equipment.

[0086] It is understood that the embodiments of this application do not limit the number of access network devices and terminal devices included in the communication system. Moreover, in addition to access network devices and terminal devices, the communication system may also include other devices or network elements, such as core network devices and relay devices. The embodiments of this application do not limit these as well.

[0087] In this context, core network equipment corresponds to different devices in different communication systems. For example, see... Figure 3 This is a schematic diagram of a 5G wireless communication system provided in an embodiment of this application. Figure 3 As shown, a 5G wireless communication system can include three parts: terminal equipment, data network (DN), and operator network. The operator network includes a radio access network and a core network. The core network includes user plane network elements and control plane network elements.

[0088] The user plane network elements of the core network include user plane functions (UPFs).

[0089] The control plane network elements of the core network include the authentication server function (AUSF) network element, access and mobility management function (AMF), session management function (SMF), network slicing selection function (NSSF), network exposure function (NEF), network repository function (NRF), policy control function (PCF), unified data management (UDM), application function (AF), network slice-specific authentication and authorization function (NSSAAF), service communication proxy (SCP), network slice admission control function (NSACF), and edge application server discovery function (EASDF), etc.

[0090] In this application embodiment, the apparatus for implementing the functions of the core network equipment can be the core network equipment itself; it can also be an apparatus capable of supporting the core network equipment in implementing the functions, such as a chip system, which can be installed in the core network equipment. In this application embodiment, the chip system can be composed of chips, or it can include chips and other discrete devices. In the technical solutions provided in this application embodiment, the core network equipment is used as an example to describe the technical solutions provided in this application embodiment.

[0091] The above content describes the system architecture and possible application scenarios applicable to the embodiments of this application. In order to better understand the technical solutions of the embodiments of this application, the relevant technical features involved in the embodiments of this application will be explained below.

[0092] Cell handover can include cell handover based on L1 and / or L2 (referred to as L1 and / or L2 handover) and cell handover based on L3 (referred to as L3 handover). Here, L1 refers to the PHY layer, L2 refers to the MAC layer, RLC layer, PDCP layer or SDAP layer, and L3 refers to the RRC layer.

[0093] L1 and / or L2 handover, also known as L1 and / or L2 layer-triggered mobility (LTM) handover, refers to cell handover operations primarily performed in L1 and / or L2 layers. For example, the terminal device sends L1 measurement results to the access network device via PHY layer control signaling (bearing the physical uplink control channel (PUCCH)). The access network device's PHY layer reads the L1 measurement results, makes a handover decision based on the L1 measurement results, and sends this handover decision to the terminal device via L1 and / or L2 signaling. This L1 and / or L2 signaling can be messages carried on the physical downlink control channel (PDCCH) or MAC control elements (MAC CE).

[0094] In LTM handover under a CU-DU separation architecture, the source DU (S-DU) is the DU to which the source cell belongs, meaning the source DU provides the source cell for the UE. The source CU (S-CU) is connected to the source DU and manages the source DU. The target DU (T-DU) is the DU to which the target cell belongs, meaning the target DU provides the target cell for the UE. The target CU (T-CU) is connected to the target DU and manages the target DU. Depending on whether the source DU and target DU are the same, and whether the source CU and target CU are the same, LTM handover can be divided into several scenarios, which are described below.

[0095] For example, in scenario 1: the source DU is different from the target DU, but the source CU and the target CU are the same.

[0096] In other words, the source cell and the target cell can be different cells provided by different DUs managed by the same CU, meaning that the terminal device can perform cell handover between different DUs managed by the same CU.

[0097] See Figure 4a This is a schematic diagram illustrating an LTM switching scenario provided in this application. Figure 4aAs shown, UE1's source cell is cell 1, and UE1's target cell is cell 2. Cell 1 belongs to a DU (Dedicated Unit), meaning UE1's source DU is DU1. Cell 2 belongs to a DU (Dedicated Unit), meaning UE1's target DU (T-DU) is DU2. DU1 is connected to CU1, and CU1 manages DU1. DU2 is connected to CU1, and CU1 manages DU2. In other words, UE1 can handover between cell 1 provided by DU1 (managed by CU1) and cell 2 provided by DU2 (managed by CU1).

[0098] See Figure 4b This is a schematic diagram illustrating an LTM switching process, as provided in this application example. Figure 4b As shown, the specific steps for cell handover between different DUs managed by the same CU are as follows:

[0099] Step 1: The CU sends the configuration information of at least one candidate cell to the UE via the source DU.

[0100] Step 2: The UE sends the measurement results of the source cell and the candidate cell to the source DU.

[0101] Step 3: The source DU sends a handover command to the UE, sending the identification information of the target cell to the UE via L1 and / or L2 signaling. The target cell is any one of the at least one candidate cell. The L1 and / or L2 signaling is still sent via the communication resources of the source cell.

[0102] Step 4: The UE performs an LTM handover from the source cell to the target cell, and uses the configuration information corresponding to the target cell received in Step 1 to access the target cell. After successful access, it starts communicating with the target cell (i.e., communicating with the target DU, or using the communication resources of the target cell to communicate).

[0103] For example, scenario two: the source DU and the target DU are the same, that is, the source CU and the target CU are also the same.

[0104] In other words, the source cell and the target cell can also be different cells provided by the same DU, meaning that the terminal device can perform cell handover between different cells provided by the same DU.

[0105] See Figure 4c This is a schematic diagram illustrating another LTM switching scenario provided in this application example. Figure 4c As shown, UE1's source cell is cell 1, and UE1's target cell is cell 2. The DU to which cell 1 belongs is DU1, meaning UE1's source DU is DU1. The DU to which cell 2 belongs is DU1, meaning UE1's target DU is DU1. In other words, UE1 can handover between cell 1 provided by DU1 and cell 2 provided by DU1.

[0106] For example, in scenario 3: the source DU is different from the target DU, and the source CU is also different from the target CU.

[0107] In other words, the source cell and the target cell can also be different cells provided by different DUs managed by different CUs, meaning that cell handover can be performed between different DUs managed by different CUs.

[0108] See Figure 4d This is a schematic diagram illustrating another LTM switching scenario provided in this application example. Figure 4d As shown, UE1's source cell is cell 1, and UE1's target cell is cell 2. Cell 1 belongs to DU1, meaning UE1's source DU is DU1. Cell 2 belongs to DU1, meaning UE1's target DU is DU1. DU1 is connected to CU1, and CU1 manages DU1. DU2 is connected to CU2, and CU2 manages DU2. This means UE1 can handover between cell 1 (managed by CU1) and cell 2 (managed by CU2).

[0109] Currently, during LTM handover in terminal devices, the L2 protocol stack is reset, which may cause handover interruption time. For example, as mentioned above... Figure 4a As shown, when a UE switches from DU1 managed by CU1 to DU2 managed by CU1, an LTM handover occurs between DUs within the same CU. The L2 protocol stack reset includes RLC layer function re-establishment and MAC layer function reset. For example, as described above... Figure 4d As shown, when the UE switches from DU1 managed by CU1 to DU2 managed by CU2, it is a cross-CU LTM handover. In addition to RLC layer function reset and MAC layer function reset, L2 protocol stack reset also includes PDCP layer function reset.

[0110] Since the PDCP layer functional re-establishment process involves replacing encryption and integrity protection key information, it introduces additional handover interruption time. Therefore, how to reduce handover interruption time and improve business experience during LTM handover is worth studying.

[0111] In view of this, embodiments of this application provide a communication method for reducing handover interruption time during LTM handover.

[0112] In the embodiments of this application, "when," "if," and "if" all refer to the device taking corresponding actions under certain objective circumstances, and are not time-limited, nor do they require the device to perform a judgment action, nor do they imply any other limitations. Unless otherwise specified, "if" and "if" can be substituted, and "when" and "in the case of" can be substituted. "When" and "if" / "if" can be substituted.

[0113] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0114] In this document, "used for indication" can include both direct and indirect indication. For example, when descriptive information I is used to indicate information J, it can mean that information I directly indicates information J or indirectly indicates information J, but it does not necessarily mean that information I carries information J.

[0115] Let information J, indicated by information I, be called the information to be indicated. In practice, there are many ways to indicate the information to be indicated, such as, but not limited to, directly indicating the information to be indicated, such as the information itself or its index. It can also be indirectly indicated by indicating other information, where there is a relationship between the other information and the information to be indicated. It can also indicate only a part of the information to be indicated, while the other parts are known or pre-agreed upon. For example, the indication of specific information can be achieved by using a pre-agreed (e.g., protocol-defined) order of various pieces of information, thereby reducing indication overhead to some extent. Simultaneously, common parts of various pieces of information can be identified and indicated uniformly to reduce the indication overhead caused by individually indicating the same information.

[0116] Furthermore, the specific instruction method can also be any existing instruction method, such as, but not limited to, the above-mentioned instruction methods and their various combinations. As described above, for example, when multiple pieces of information of the same type need to be indicated, the instruction methods for different pieces of information may differ. In specific implementation, the required instruction method can be selected according to specific needs. This application embodiment does not limit the selected instruction method. Therefore, the instruction methods involved in this application embodiment should be understood to cover various methods that enable the party to be instructed to obtain the information to be indicated.

[0117] In the embodiments of this application, "send" and "receive" indicate the direction of signal transmission. For example, "send information to XX" can be understood as the destination of the information being XX, which may include direct transmission via the air interface or indirect transmission via the air interface by other units or modules. "Receive information from YY" can be understood as the source of the information being YY, which may include direct reception from YY via the air interface or indirect reception from YY via the air interface by other units or modules. "Send" can also be understood as the "output" of the chip interface, and "receive" can also be understood as the "input" of the chip interface.

[0118] Information may undergo necessary processing, such as encoding and modulation, between the source and destination ends, but the destination end can understand the valid information from the source end. Similar statements in the embodiments of this application can be understood in a similar way, and will not be repeated here.

[0119] In this application embodiment, the number of nouns, unless otherwise specified, refers to "singular nouns or plural nouns," that is, "one or more." "At least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. The character " / " can indicate that the related objects before and after are in an "or" relationship. For example, A / B means: A or B. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c means: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0120] In this application, the ordinal numbers such as "first" and "second" are used to distinguish multiple objects, and are not used to limit the size, content, order, timing, priority, or importance of the multiple objects. For example, "first information" and "second information" refer to two different pieces of information, and do not indicate a difference in priority or importance between the two pieces of information. For a technical feature, the technical features within that technical feature are distinguished by "A," "B," "C," and "D," and there is no sequential or hierarchical order among the technical features described by "A," "B," "C," and "D." For example, in this document, situation A and situation B are only used to distinguish different contents, and do not limit the sequential or hierarchical order, priority, or importance between situation A and situation B.

[0121] The solution provided by the embodiments of this application will be described in detail below with reference to the accompanying drawings. In the following description, the communication method provided by the embodiments of this application is applied to... Figures 1-3 The communication system shown is an example. The communication system and application scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of communication systems and the emergence of new application scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0122] The following describes the communication method provided in this application, using an embodiment executed by a terminal device, an access network device, and a core network device as an example. The steps executed by the terminal device can be implemented by the terminal device itself or by components within the terminal device (such as chips, processing units, or processor modules). The terminal device can be... Figures 1-3 The terminal device shown, or it could be Figures 1-3 The steps performed by the access network device can be implemented by the access network device itself or by components within the access network device (such as chips, processing units, or processor modules). The access network device can be... Figures 1-3 The access network device shown, or it could be Figures 1-3 The core network equipment contains chips (systems). The steps executed by the core network equipment can be implemented by the core network equipment itself, or by components within the core network equipment (such as chips, processing units, or processor modules). The core network equipment can be... Figures 1-3 The access network device shown, or it could be Figures 1-3 The core network of the chip (system).

[0123] When this communication method is implemented by components in terminal equipment, access network equipment, and core network equipment, the receiving and transmitting steps can be understood as the component communicating with other components, such as communication between a baseband chip and a radio frequency circuit. In the embodiments of this application, the processing performed by a single execution entity can also be divided into multiple execution entities, which can be logically and / or physically separated. For example, the processing performed by the access network equipment can be divided into execution by at least one of the CU and DU.

[0124] See Figure 5 , Figure 5 This is a flowchart illustrating a communication method provided in an embodiment of this application. Figure 5 As shown, the communication method includes the following steps.

[0125] S501, the source access network device sends a first request message to the target access network device, and correspondingly, the target access network device receives the first request message from the source access network device. The first request message is used to request configuration information of at least one candidate cell of the terminal device, and includes first information indicating that the first protocol layer function is provided by the source access network device.

[0126] The source access network device can be the access network device to which the source cell of the terminal device belongs. The source access network device can adopt a CU-DU separation architecture, that is, the source access network device can be a source CU and / or a source DU, wherein the source DU can be used to provide the source cell of the terminal device, and this application embodiment does not limit this.

[0127] The target access network device can be the access network device to which at least one candidate cell of the terminal device belongs. The target access network device can adopt a CU-DU separation architecture, meaning that the target access network device can be a target CU and / or a target DU, wherein the target DU can be used to provide at least one candidate cell for the terminal device; this embodiment of the application does not limit this. It should be understood that before performing cell handover, the target access network device can also be referred to as a candidate access network device, the target CU can also be referred to as a candidate CU, and the target DU can also be referred to as a candidate CU.

[0128] Among them, the source DU and the target DU can be different, and the source CU and the target CU can be different. That is to say, the LTM handover of the terminal equipment from the source cell to one of the candidate cells in at least one candidate cell is a cross-CU LTM handover.

[0129] For ease of explanation, the following text uses the source access network device as the source CU and the target access network device as the target CU as an example.

[0130] When a terminal device performs an LTM handover across CUs, the L2 protocol stack reset involves RLC layer function re-establishment, MAC layer function reset, and PDCP layer function re-establishment. The PDCP layer function re-establishment process involves changing the encryption and integrity protection key information, which introduces additional handover interruption time. Therefore, to reduce handover interruption time, the source CU and target CU can choose not to perform PDCP layer function re-establishment. This can be understood as the PDCP layer function residing in the source CU, meaning the PDCP layer function is provided by the source CU; or it can be understood as the CU function (e.g., RRC layer function, SDAP layer function, and PDCP layer function) residing in the source CU, meaning the CU function is provided by the source CU; or it can be understood as the source CU being the anchor point CU.

[0131] In the specific implementation process Figure 6 A flowchart illustrating another communication method provided in an embodiment of this application is shown below. Figure 6 As shown, the above S501 may include the following steps A1-A3.

[0132] In step A1, the source CU can send a first request message to the target CU, and correspondingly, the target CU can receive the first request message from the source CU.

[0133] The first request message is used to request configuration information of at least one candidate cell from the terminal device.

[0134] To reduce handover interruption time, the first protocol layer function (or CU function) can be provided by the source CU. That is, the configuration information related to the first protocol layer function can be generated by the source CU instead of the target CU. Therefore, the first request message is not used to request configuration information related to the first protocol layer function, but only to request configuration information related to the second protocol layer function (or DU function). This will be explained below.

[0135] 1) Configuration information related to the functions of the first protocol layer.

[0136] The first protocol layer function may include one or more of the following: RRC layer function, PDCP layer function, and SDAP layer function. The configuration information related to the first protocol layer function can be understood as the CU-side configuration information generated by the CU.

[0137] 2) Configuration information related to the second protocol layer functions.

[0138] The second protocol layer function may include one or more of the RLC layer function, MAC layer function, and PHY layer function. The configuration information related to the second protocol layer function can be understood as the DU-side configuration information generated by the DU.

[0139] In other words, when the first protocol layer function is provided by the source CU and the second protocol layer function is provided by the target DU, the configuration information related to the first protocol layer function is generated by the source CU and the configuration information related to the second protocol layer function is generated by the target DU; when the first protocol layer function is provided by the target CU and the second protocol layer function is provided by the target DU, the configuration information related to the first protocol layer function is generated by the target CU and the configuration information related to the second protocol layer function is generated by the target DU.

[0140] In this embodiment, the first protocol layer function is provided by the source CU, which can be understood as the first protocol layer function residing in the source CU, or as the source CU being the anchor CU. The first protocol layer function is provided by the target CU, which can be understood as the first protocol layer function not residing in the source CU, but switching to the target CU, or as the source CU not being the anchor CU. This application does not limit this aspect.

[0141] The first request message may be a switching request message; or other messages, such as a partial function switching request message, which is not limited in this embodiment.

[0142] The first request message may include first information. This first information may be used to indicate that the first protocol layer function is provided by the source CU.

[0143] Specifically, the first information can directly indicate that the first protocol layer function is provided by the source CU; or, the first information can indirectly indicate that the first protocol layer function is provided by the source CU. For example, the first information can indicate that the type of the first request message is a first type (e.g., a partial function switching request message). The first type indicates that the first protocol layer function is provided by the source CU. The first type can be pre-configured, standard-defined, or agreed upon in advance by the terminal device and the access network device; this application embodiment does not limit this.

[0144] It is understandable that, regarding the first piece of information, the target CU can determine that it does not need to generate configuration information related to the first protocol layer function, meaning that the configuration information related to the first protocol layer function is generated by the source CU. Optionally, the target CU can also determine that after the terminal device switches from the source cell provided by the source DU to one of the candidate cells provided by the target DU, it does not need to initiate a path switch to the core network device, that is, it does not need to request the core network device to switch the endpoint of the downlink user plane tunnel (i.e., from the core network device to the CU) from the source CU to the target CU.

[0145] In one possible implementation, since the first protocol layer function includes transmitting different services using different radio bearers, when the first protocol layer function is provided by the source CU, the starting point of the uplink user plane tunnel corresponding to the radio bearer is the target DU, and the ending point is the source CU; when the first protocol layer function is provided by the target CU, the starting point of the uplink user plane tunnel corresponding to the radio bearer is the target DU, and the ending point is the target CU. Therefore, in order to realize that the first protocol layer function is provided by the source CU, the information of the first radio bearer to be established should be determined by the source CU, and the first request message sent by the source CU to the target CU may also include the information of the first radio bearer to be established.

[0146] The information of the first radio bearer to be established can be used to generate first configuration information for at least one candidate cell of the terminal device. The first configuration information can be configuration information related to the second protocol layer function. For example, the first configuration information can be configuration information related to one or more of the RLC layer function, MAC layer function, and PHY layer function. It can be understood that the first configuration information is the DU-side configuration information generated by the target DU.

[0147] The first radio bearer to be established may include one or more radio bearers to be established, which may be a data radio bearer (DRB) to be established and / or a signaling radio bearer (SRB) to be established. This application embodiment does not limit this.

[0148] Specifically, the information of the first radio bearer to be established may include one or more of the following: the quality of service (QoS) information of the first radio bearer to be established, such as the QoS parameters of the first DRB to be established and the QoS parameters of the first SRB to be established; the tunnel information of the first radio bearer to be established, such as the identifier or address of the endpoint (i.e., source CU) of the uplink user plane tunnel corresponding to the first DRB to be established, such as the general packet radio service tunneling protocol-tunnelendpoint identifier (GTP-TEID) of the source CU and the Internet protocol address (IP) address of the source CU; and the identification information of the first radio bearer to be established, such as the identifier of the first DRB to be established and the identifier of the first SRB to be established. This application embodiment does not limit this.

[0149] In one possible implementation, since the configuration information related to the second protocol layer function is generated by the target DU, in order to make the configuration information related to the second protocol layer function generated by the target DU suitable for the terminal device, the first request message may also include configuration information preferred by the terminal device, such as the discontinuous reception (DRX) period preferred by the terminal device.

[0150] Furthermore, since the configuration information related to the first protocol layer function is generated by the source CU, and the first protocol layer function may include RRC layer functions, if the RRC version of the source CU is incompatible with the RRC parameters corresponding to the functions supported by the target DU, the source CU may be unable to generate configuration information related to some communication functions. Therefore, even if the target DU supports these communication functions, the target DU does not need to generate configuration information related to the second protocol layer function when generating configuration information related to these communication functions. Thus, to ensure that the configuration information related to the second protocol layer function generated by the target DU is suitable for the source CU, the first request message may also include the RRC version information of the source CU.

[0151] It is understandable that for some information included in the aforementioned first request message, such as information about the first radio bearer to be established, configuration information preferred by the terminal device, and RRC version information of the source CU, since this information is used by the target DU to generate configuration information related to the second protocol layer function, the target CU does not need to interpret its contents, but can simply forward it to the target DU. To reduce the overhead of this information, it can be a container structure. For example, for the interface between the source CU and the target CU (e.g., the Xn interface), a container can be set up for the interface between the target CU and the target DU (e.g., the F1 interface).

[0152] In one possible implementation, since the configuration information related to the first protocol layer function includes configuration information related to neighbor cell measurement, in order to enable the first protocol layer function to be provided by the source CU, that is, the source CU generates configuration information related to the first protocol layer function, the target CU can send second information to the source CU, and correspondingly, the source CU receives the second information from the target CU.

[0153] The second information may include information about neighboring cells of the cell managed by the target CU, and can be used to generate second configuration information for at least one candidate cell of the terminal device. The second configuration information may be configuration information related to the first protocol layer function. For example, the second configuration information may be configuration information related to one or more of the RRC layer function, PDCP layer function, and SDAP layer function. The configuration information related to the RRC layer function may include configuration information related to neighbor cell measurement. In other words, the information about neighboring cells of the cell managed by the target CU can be used to generate configuration information related to neighbor cell measurement. It can be understood that the second configuration information is CU-side configuration information generated by the source CU.

[0154] The second information may be encapsulated or carried within the first confirmation message, wherein the first confirmation message is a message in response to the first request message; or other messages, which may be messages sent by the target CU before receiving the first request message, or messages sent by the target CU after sending the first confirmation message. This application embodiment does not limit this.

[0155] In step A2, the target CU sends a second request message to the target DU, and the target DU receives the second request message from the target CU.

[0156] Step A2 is an optional step.

[0157] After receiving the first request message, the target CU can perform admission control. That is, after the target CU receives the request for the first protocol layer function provided by the source CU, if the target CU agrees to the source CU's request, the target CU sends a second request message to the target DU.

[0158] It is understood that the second request message can be used to request configuration information related to the second protocol layer function of at least one candidate cell of the terminal device.

[0159] The second request message may include one or more of the following: first information; information about the first radio bearer to be established.

[0160] The second request message may be a UE context setup request message or other messages, and this application embodiment does not limit this.

[0161] In one possible implementation, the second request message may further include configuration information preferred by the terminal device, such as the DRX period preferred by the terminal device, so that the configuration information generated by the target CU related to the second protocol layer function is suitable for the terminal device.

[0162] The second request message may also include the RRC version information of the source CU to ensure that the configuration information related to the second protocol layer function generated by the target DU is suitable for the source CU.

[0163] In step A3, the target DU sends a second confirmation message to the target CU, and the target CU receives the second confirmation message from the target DU.

[0164] Step A3 is optional.

[0165] After receiving the second request message, the target DU can generate first configuration information for at least one candidate cell of the terminal device. In other words, the first configuration information is the DU-side configuration information generated by the target DU.

[0166] It is understood that the second confirmation message may include one or more of the following: first configuration information of at least one candidate cell of the terminal device; information of the first established radio bearer.

[0167] The information of the established first radio bearer can be used to generate second configuration information for at least one candidate cell of the terminal device.

[0168] The established first radio bearer may include one or more established radio bearers, which may be established DRBs and / or established SRBs, and this application embodiment does not limit this.

[0169] Specifically, the information of the established first radio bearer may include one or more of the following: QoS information of the established first radio bearer, such as the QoS parameters of the established first DRB and the QoS parameters of the established first SRB; tunnel information of the established first radio bearer, such as the identifier or address of the starting point (i.e., the target DU) of the downlink user plane tunnel corresponding to the established first DRB, such as the GTP-TEID of the target DU and the IP address of the target DU; and identification information of the established first radio bearer, such as the identifier of the established first DRB and the identifier of the established first SRB. This application embodiment does not limit this.

[0170] The second confirmation message may be a UE context setup response message or other messages, and this application embodiment does not limit this.

[0171] S502, the target access network device sends a first confirmation message to the source access network device, and correspondingly, the source access network device receives the first confirmation message from the target access network device. The first confirmation message includes first configuration information of at least one candidate cell of the terminal device.

[0172] In the specific implementation process, such as Figure 6 As shown, the above S502 may include the following steps B1-B2.

[0173] In step B1, the target CU sends a first acknowledgment message to the source CU, and correspondingly, the source CU receives the first acknowledgment message from the target CU.

[0174] The first confirmation message includes the first configuration information of at least one candidate cell of the terminal device.

[0175] In one possible implementation, in order to enable the first protocol layer function to be provided by the source CU, that is, the source CU generates configuration information related to the first protocol layer function, the first confirmation message may also include information about the established first radio bearer.

[0176] The first confirmation message may be a switch confirmation message; or other messages, such as a partial switch confirmation message, which is not limited in this application embodiment.

[0177] In step B2, the source CU sends the first configuration information of at least one candidate cell of the terminal device to the terminal device, and correspondingly, the terminal device receives the first configuration information of at least one candidate cell of the terminal device from the source CU.

[0178] Step B2 is an optional step.

[0179] The first configuration information can be used to indicate that the first protocol layer function is provided by the source CU. In other words, the first configuration information is used to instruct the terminal device not to re-establish the first protocol layer function.

[0180] The first configuration information may be encapsulated or carried in a downlink RRC message or other messages, and this application embodiment does not limit this.

[0181] It is understandable that if the source CU only sends the first configuration information of at least one candidate cell of the terminal device to the terminal device, then after the terminal device receives the first configuration information of at least one candidate cell of the terminal device from the source CU, it can determine that the first protocol layer function is provided by the source CU based on the first configuration information. In other words, the terminal device does not perform the first protocol layer function re-establishment.

[0182] Optionally, the source CU sends first configuration information and second configuration information of at least one candidate cell of the terminal device to the terminal device, and correspondingly, the terminal device receives the first configuration information and second configuration information of at least one candidate cell of the terminal device from the source CU.

[0183] After receiving the first confirmation message, the source CU can generate second configuration information for at least one candidate cell of the terminal device. In other words, the second configuration information is the CU-side configuration information generated by the source CU.

[0184] The second configuration information can be used to indicate that the first protocol layer function is provided by the source CU. In other words, the second configuration information is used to instruct the terminal device not to re-establish the first protocol layer function.

[0185] Specifically, the second configuration information can directly indicate that the first protocol layer function is provided by the source CU; or, the second configuration information can also indirectly indicate that the first protocol layer function is provided by the source CU. For example, taking the first protocol layer function as the PDCP layer function, the second configuration information may not include the configuration information related to the PDCP layer function, so as to indicate that the terminal device can use the original configuration information related to the PDCP layer function.

[0186] The first configuration information and the second configuration information can be encapsulated or carried in downlink RRC messages or other messages, and this application embodiment does not limit this.

[0187] It is understandable that if the source CU sends the first configuration information and the second configuration information of at least one candidate cell of the terminal device to the terminal device, then after the terminal device receives the first configuration information and the second configuration information of at least one candidate cell of the terminal device from the source CU, it can determine that the first protocol layer function is provided by the source CU according to the second configuration information. In other words, the terminal device does not perform the first protocol layer function re-establishment.

[0188] It is understood that, based on steps A1-A3 and B1-B2 above, the configuration information (e.g., first configuration information and second configuration information) of at least one candidate cell of the terminal device is sent to the terminal device. This enables the terminal device to perform LTM handover from the source cell provided by the source DU to one of the candidate cells provided by the target DU, i.e., to perform cross-CU LTM handover, based on the configuration information of at least one candidate cell of the terminal device. Furthermore, during cross-CU LTM handover, the terminal device can avoid re-establishing the first protocol layer function; that is, the first protocol layer function resides in the source CU, thereby reducing handover interruption time.

[0189] In one possible implementation, after the terminal device performs an LTM handover across CUs, the source CU and the target CU can re-establish the first protocol layer function. That is, the first protocol layer function is switched from being provided by the source CU to being provided by the target CU.

[0190] It can be understood that the source CU and source DU here refer to the CU and DU of the serving cell previously belonging to the terminal device, while the target CU and target DU refer to the CU and DU of the serving cell currently belonging to the terminal device. For ease of explanation, they will still be referred to as source CU and source DU, target CU and target DU in the following text. The serving cell previously belonging to the terminal device is the source cell, and the serving cell currently belonging to the terminal device is the first candidate cell among at least one candidate cell.

[0191] The initiator of the first protocol layer function re-establishment can be the source CU. For example, when the source CU is heavily loaded or the link latency between the source CU and the target DU is large, in order to reduce the load of the source CU or the link latency between the source CU and the target DU, the source CU can switch the provision of the first protocol layer function from the source CU to the target CU.

[0192] Alternatively, the initiator of the first protocol layer function re-establishment can also be the target CU. For example, since the source CU is unaware of the specific resource situation of the target DU, the resource utilization of the target DU is low. In order to improve the resource utilization of the target DU, the target CU can switch the provision of the first protocol layer function from the source CU to the provision of the target CU.

[0193] Alternatively, the initiator of the first protocol layer function re-establishment can also be the target DU. For example, when the link latency between the source CU and the target DU is large, in order to reduce the link latency between the source CU and the target DU, the target DU can switch the first protocol layer function from being provided by the source CU to being provided by the target CU.

[0194] The following will be introduced in different situations.

[0195] In scenario A, the initiator of the first protocol layer functional re-establishment can be the source CU.

[0196] For example, Figure 7 A flowchart illustrating another communication method provided in an embodiment of this application is shown below. Figure 7 As shown, after the terminal device performs an LTM handover across CUs, the following steps C1-C10 can also be executed.

[0197] In step C1, the source CU sends a third request message to the target CU, and the target CU receives the third request message from the source CU.

[0198] The third request message can be used to indicate that the first protocol layer function is provided by the target CU.

[0199] It is understood that the third request message may be a switch request message or other messages, and this application embodiment does not limit this.

[0200] The third request message can be used to request configuration information for at least one candidate cell of the terminal device.

[0201] In step C2, the target CU sends a fourth request message to the target DU, and the target DU receives the fourth request message from the target CU.

[0202] After receiving the third request message, the target CU can perform admission control. That is, after the target CU determines that the request to switch the first protocol layer function of the receiving source CU from the source CU to the target CU is being made, if the target CU agrees to the source CU's request, the target CU sends a fourth request message to the target DU.

[0203] It is understood that the fourth request message can be used to request configuration information related to the second protocol layer function of at least one candidate cell of the terminal device.

[0204] The fourth request message may include one or more of the following: third information; information about the second radio bearer to be established;

[0205] The third piece of information can be used to indicate that the first protocol layer function is provided by the target CU.

[0206] The information of the second radio bearer to be established can be used to generate third configuration information for at least one candidate cell of the terminal device. This third configuration information can be configuration information related to the second protocol layer function. For example, the third configuration information can be configuration information related to one or more of the RLC layer function, MAC layer function, and PHY layer function. It can be understood that the first configuration information is the DU-side configuration information regenerated by the target DU.

[0207] The second radio bearer to be established may include one or more radio bearers to be established, which may be a DRB to be established and / or an SRB to be established. This application embodiment does not limit this.

[0208] Specifically, the information of the second radio bearer to be established may include one or more of the following: QoS information of the second radio bearer to be established, such as the QoS parameters of the second DRB to be established and the QoS parameters of the second SRB to be established; tunnel information of the second radio bearer to be established, such as the identifier or address of the endpoint (i.e., the target CU) of the uplink user plane tunnel corresponding to the second DRB to be established, such as the GTP-TEID of the target CU and the IP address of the target CU; and identification information of the second radio bearer to be established, such as the identifier of the second DRB to be established and the identifier of the second SRB to be established. This application embodiment does not limit this.

[0209] It is understandable that, since the first protocol layer function can transmit different services through different radio bearers, when the first protocol layer function is provided by the source CU, the starting point of the uplink user plane tunnel corresponding to that radio bearer is the target DU, and the ending point is the source CU; when the first protocol layer function is provided by the target CU, the starting point of the uplink user plane tunnel corresponding to that radio bearer is the target DU, and the ending point is the target CU. Therefore, in order to realize that the first protocol layer function is provided by the target CU, the requirement of the radio bearer should be determined by the target CU. Thus, the fourth request message sent by the target CU to the target DU can also include information about the second radio bearer to be established.

[0210] The fourth request message may be a UE context modification request message or other messages, and this application embodiment does not limit this.

[0211] In step C3, the target DU sends a fourth confirmation message to the target CU, and the target CU receives the fourth confirmation message from the target DU.

[0212] After receiving the fourth request message, the target DU can generate third configuration information for at least one candidate cell of the terminal device. In other words, the third configuration information is the DU-side configuration information regenerated by the target DU.

[0213] It is understood that the fourth confirmation message may include one or more of the following: third configuration information of at least one candidate cell of the terminal device; information of the established second radio bearer.

[0214] The established information of the second radio bearer is used to generate fourth configuration information for at least one candidate cell of the terminal device. This fourth configuration information is configuration information related to the functions of the first protocol layer. For example, the fourth configuration information may be configuration information related to one or more of the RRC layer functions, PDCP layer functions, and SDAP layer functions. It can be understood that the fourth configuration information is the CU-side configuration information generated by the target CU.

[0215] The established second radio bearer may include one or more established radio bearers, which may be established DRBs and / or established SRBs, and this application embodiment does not limit this.

[0216] Specifically, the information of the established second radio bearer may include one or more of the following: QoS information of the established second radio bearer, such as the QoS parameters of the established second DRB and the QoS parameters of the established second SRB; tunnel information of the established second radio bearer, such as the identifier or address of the starting point (i.e., the target DU) of the downlink user plane tunnel corresponding to the established second DRB, such as the GTP-TEID of the target DU and the IP address of the target DU; and identification information of the established second radio bearer, such as the identifier of the established second DRB and the identifier of the established second SRB. This application embodiment does not limit this.

[0217] The fourth confirmation message may be a UE context modification response message or other messages, and this application embodiment does not limit this.

[0218] In step C4, the target CU sends a third acknowledgment message to the source CU, and correspondingly, the source CU receives the third acknowledgment message from the target CU.

[0219] The third confirmation message may include third configuration information and fourth configuration information of at least one candidate cell of the terminal device.

[0220] The third confirmation message can be a switch confirmation message or other messages, and this application embodiment does not limit this.

[0221] It is understandable that after the target CU receives the fourth confirmation message, the target CU can generate fourth configuration information for at least one candidate cell of the terminal device. In other words, the fourth configuration information is the CU-side configuration information generated by the target CU.

[0222] In step C5, the source CU sends the fourth information to the target CU, and the target CU receives the fourth information from the source CU accordingly.

[0223] In step C6, the target CU sends the fourth information to the target DU, and correspondingly, the target DU receives the fourth information from the target CU.

[0224] In step C7, the target DU sends the fourth information to the terminal device, and the terminal device receives the fourth information from the target DU.

[0225] The fourth information can be obtained by encrypting and protecting the integrity of the third and fourth configuration information of at least one candidate cell of the terminal device based on the first key. The first key can correspond to the source CU, that is, the first key is the key of the source CU.

[0226] The fourth piece of information can be used to indicate a switch from providing the first protocol layer function to providing it to the target CU. In other words, the fourth piece of information is used to instruct the terminal device to re-establish the first protocol layer function.

[0227] The fourth piece of information may be encapsulated or carried in a downlink RRC message or other messages, and this application embodiment does not limit this.

[0228] It is understandable that since the terminal device only has the key of the source CU and not the key of the target CU, the source CU can only use the key of the source CU to encrypt and protect the integrity of the third configuration information and the fourth configuration information of at least one candidate cell of the terminal device to obtain the fourth information, which is then sent to the terminal device via the target CU and the target DU.

[0229] After receiving the fourth information, the terminal device can first use the key of the source CU to decrypt the fourth information to obtain the third and fourth configuration information of at least one candidate cell of the terminal device. Then, based on the third and fourth configuration information of at least one candidate cell of the terminal device, the terminal device can determine the key of the target CU, so that the terminal device can use the key of the target CU to communicate.

[0230] Optionally, since the data cached by the target DU is encrypted and protected for integrity using the source CU's key, after the target DU sends the fourth message, or after confirming that the terminal device has successfully received the fourth message, the target DU can perform RLC layer function re-establishment and MAC layer function reset to clear the cached data encrypted and protected for integrity using the source CU's key. Furthermore, after the target DU successfully completes the RLC layer function re-establishment, the target DU can also send uplink user plane data to the target CU based on the established second radio bearer.

[0231] In step C8, the terminal device sends the sixth information and / or the first data to the target DU, and correspondingly, the target DU receives the sixth information and / or the first data from the terminal device.

[0232] In step C9, the target DU sends the fifth information and / or the first data to the target CU, and correspondingly, the target CU receives the fifth information and / or the first data from the target DU.

[0233] The sixth piece of information can be used to indicate that the terminal device has successfully completed the first protocol layer function re-establishment (e.g., PDCP layer function re-establishment). The sixth piece of information is obtained by encrypting and protecting its integrity based on the second key.

[0234] The sixth piece of information may be encapsulated or carried in an uplink RRC message; or other messages, which are not limited in this application embodiment.

[0235] The fifth piece of information can be used to indicate that the terminal device has accessed the first candidate cell among at least one candidate cell of the terminal device. Optionally, the fifth piece of information can also be used to indicate that the terminal device has successfully completed the first protocol layer function re-establishment.

[0236] The fifth piece of information may be encapsulated or carried in an access success notification message; or other messages, such as an uplink RRC message transfer message, which is not limited in this embodiment of the application.

[0237] The first and second data are uplink user plane data. The first data is obtained by encrypting and protecting the integrity of the second data using the second key.

[0238] The second key corresponds to the first candidate cell, meaning the second key is the key for the target CU.

[0239] It is understandable that after the terminal device determines the key of the target CU, since the key of the target CU may include the key corresponding to at least one candidate cell of the terminal device, and the keys corresponding to different candidate cells are different, if the terminal device has accessed the first candidate cell among at least one candidate cell of the terminal device and has completed the first protocol layer function re-establishment, the terminal device can use the key corresponding to the first candidate cell to encrypt and protect the integrity of the second data, obtain the first data, and send the first data and / or the sixth information used to indicate that the terminal device has successfully completed the first protocol layer function re-establishment to the target DU.

[0240] After the target DU receives the first data and / or the sixth information, the target DU may send the first data and / or the fifth information, which is used to indicate that the terminal device has accessed at least one candidate cell in the candidate cells of the terminal device, to the target CU.

[0241] After the target CU receives the first data and / or the fifth information, the terminal device can use the key corresponding to the first candidate cell to decrypt the first data to obtain the second data. Based on the second data or the fifth information, the terminal device can determine that it has successfully applied the third and fourth configuration information of at least one candidate cell of the terminal device, that is, it has successfully completed the first protocol layer function re-establishment.

[0242] Optionally, after the target CU receives the first data and / or the sixth information, the target CU may send lower user plane data to the target DU based on the established second radio bearer.

[0243] In step C10, the target CU sends a fifth request message to the core network device, and the core network device receives the fifth request message from the target CU.

[0244] The fifth request message is used to request the core network device to switch the endpoint of the downlink user plane tunnel (i.e., from the core network device to the CU) from the source CU to the target CU.

[0245] The fifth request message may be a path switching request message or other messages, which are not limited in this application.

[0246] The core network equipment can be an AMF network element or other network elements, and this application embodiment does not limit this.

[0247] In scenario B, the initiator of the first protocol layer functional re-establishment can be the target CU.

[0248] For example, Figure 8 A flowchart illustrating another communication method provided in an embodiment of this application is shown below. Figure 8 As shown, after the terminal device performs an LTM handover across CUs, the following steps D1-D9 can also be executed.

[0249] In step D1, the target CU sends a fourth request message to the target DU, and the target DU receives the fourth request message from the target CU.

[0250] Step D1 can be referred to step C2 above, and will not be repeated here.

[0251] In step D2, the target DU sends a fourth confirmation message to the target CU, and the target CU receives the fourth confirmation message from the target DU.

[0252] Step D2 can be referred to step C3 above, and will not be repeated here.

[0253] In step D3, the target CU sends a first indication message to the source CU, and the source CU receives the first indication message from the target CU.

[0254] The first instruction message can be used to indicate that the first protocol layer function is provided by the target CU.

[0255] The first instruction message may include third and fourth configuration information of at least one candidate cell of the terminal device.

[0256] The first instruction message can be a transfer request message, such as a CU anchor point transfer request message, a PDCP layer function transfer request message, or a CU function transfer request message; or other messages, which are not limited in this embodiment.

[0257] In step D4, the source CU sends the fourth information to the target CU, and the target CU receives the fourth information from the source CU accordingly.

[0258] Step D4 can be referred to step C5 above, and will not be repeated here.

[0259] In step D5, the target CU sends the fourth information to the target DU, and correspondingly, the target DU receives the fourth information from the target CU.

[0260] Step D5 can be referred to step C6 above, and will not be repeated here.

[0261] In step D6, the target DU sends the fourth information to the terminal device, and the terminal device receives the fourth information from the target DU.

[0262] Step D6 can be referred to step C7 above, and will not be repeated here.

[0263] In step D7, the terminal device sends the sixth information and / or the first data to the target DU, and correspondingly, the target DU receives the sixth information and / or the first data from the terminal device.

[0264] Step D7 can be referred to step C8 above, and will not be repeated here.

[0265] In step D8, the target DU sends the fifth information and / or the first data to the target CU, and correspondingly, the target CU receives the fifth information and / or the first data from the target DU.

[0266] Step D8 can be referred to step C9 above, and will not be repeated here.

[0267] In step D9, the target CU sends a fifth request message to the core network device, and the core network device receives the fifth request message from the target CU.

[0268] Step D9 can be referred to step C10 above, and will not be repeated here.

[0269] In case C, the initiator of the first protocol layer functional re-establishment can be the target DU.

[0270] For example, Figure 9 A flowchart illustrating another communication method provided in an embodiment of this application is shown below. Figure 9 As shown, after the terminal device performs an LTM handover across CUs, the following steps E1-E11 can also be executed.

[0271] In step E1, the target DU sends a second indication message to the target CU, and correspondingly, the target CU receives the second indication message from the target DU.

[0272] The second instruction message can be used to indicate that the first protocol layer function is provided by the target CU.

[0273] The second instruction message can be a transfer request message, such as a CU anchor point transfer request message, a PDCP layer function transfer request message, or a CU function transfer request message; or other messages, which are not limited in this embodiment.

[0274] In step E2, the target CU sends a fourth request message to the target DU, and the target DU receives the fourth request message from the target CU.

[0275] Step E2 can be referred to step C2 above, and will not be repeated here.

[0276] In step E3, the target DU sends a fourth confirmation message to the target CU, and the target CU receives the fourth confirmation message from the target DU.

[0277] Step E3 can be referred to step C3 above, and will not be repeated here.

[0278] In step E4, the target CU sends a first indication message to the source CU, and the source CU receives the first indication message from the target CU.

[0279] Step E4 can be referred to step D3 above, and will not be repeated here.

[0280] In step E5, the source CU sends the fourth information to the target CU, and the target CU receives the fourth information from the source CU accordingly.

[0281] Step E5 can be referred to as step C5 above, and will not be repeated here.

[0282] In step E6, the target CU sends the fourth information to the target DU, and correspondingly, the target DU receives the fourth information from the target CU.

[0283] Step 6 can be referred to as step C6 above, and will not be repeated here.

[0284] In step E7, the target DU sends the fourth information to the terminal device, and the terminal device receives the fourth information from the target DU.

[0285] Step E7 can be referred to step C7 above, and will not be repeated here.

[0286] In step E8, the terminal device sends the sixth information and / or the first data to the target DU, and correspondingly, the target DU receives the sixth information and / or the first data from the terminal device.

[0287] Step E8 can be referred to as step C8 above, and will not be repeated here.

[0288] In step E9, the target DU sends the fifth information and / or the first data to the target CU, and correspondingly, the target CU receives the fifth information and / or the first data from the target DU.

[0289] Step E9 can be referred to step C9 above, and will not be repeated here.

[0290] In step E10, the target CU sends a fifth request message to the core network device, and the core network device receives the fifth request message from the target CU.

[0291] Step E10 can be referred to as step C10 above, and will not be repeated here.

[0292] It is understood that the above embodiments of this application can be implemented individually or in combination with each other, and the embodiments of this application are not limited.

[0293] The methods provided by the embodiments of this application have been described above with reference to the accompanying drawings. The apparatus provided by the embodiments of this application will be described below with reference to the accompanying drawings.

[0294] Based on the same technical concept, embodiments of this application provide a communication device, which includes a module / unit / means for executing the method performed by the device in the above-described method embodiments. This module / unit / means can be implemented in software, or in hardware, or implemented by hardware executing corresponding software.

[0295] For example, see Figure 10 This is a schematic diagram of a communication device 1000, which includes a transceiver module 1001 and a processing module 1002.

[0296] When the device 1000 is a target access network device, the functions of each module of the device 1000 are as follows:

[0297] The transceiver module 1001 is configured to receive a first request message from a source access network device, wherein the first request message is used to request configuration information of at least one candidate cell of a terminal device, the first request message includes first information, the first information being used to indicate that a first protocol layer function is provided by the source access network device; and to send a first confirmation message to the source access network device, wherein the first confirmation message includes the first configuration information of the at least one candidate cell.

[0298] Alternatively, when the device 1000 is a source access network device, the functions of each module of the device 1000 are as follows:

[0299] The transceiver module 1001 is configured to send a first request message to a target access network device, wherein the first request message is used to request configuration information of at least one candidate cell of the terminal device, the first request message includes first information, the first information being used to indicate that a first protocol layer function is provided by the source access network device; and to receive a first confirmation message from the target access network device, wherein the first confirmation message includes the first configuration information of the at least one candidate cell.

[0300] In practical implementation, the above-mentioned device 1000 can have various product forms. Several possible product forms are introduced below.

[0301] See Figure 11 The diagram shows another communication device. The communication device 1100 includes a processor 1101 and an interface circuit 1102. The interface circuit 1102 is used to receive signals from other communication devices outside the communication device and transmit them to the processor 1101, or to send signals from the processor 1101 to other communication devices outside the communication device. The processor 1101 is used to implement the methods executed by the network device or terminal device in the above method embodiments through logic circuits or execution instructions.

[0302] The processor 1101 and the interface circuit 1102 are coupled to each other. It is understood that the interface circuit 1102 can be a transceiver or an input / output interface. Optionally, the communication device 1100 may also include a memory 1103 for storing instructions executed by the processor 1101, or storing input data required by the processor 1101 to execute instructions, or storing data generated after the processor 1101 executes instructions.

[0303] It should be understood that the processor mentioned in the embodiments of this application can be implemented in hardware or software. When implemented in hardware, the processor can be a logic circuit, integrated circuit, etc. When implemented in software, the processor can be a general-purpose processor, implemented by reading software code stored in memory.

[0304] For example, the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0305] It should be understood that the memory mentioned in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0306] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component, the memory (storage module) can be integrated into the processor.

[0307] It should be noted that the memories described herein are intended to include, but are not limited to, these and any other suitable types of memories.

[0308] Based on the same technical concept, embodiments of this application also provide a computer-readable storage medium storing a computer program or instructions, which, when executed by a processor, causes the methods executed by the terminal device, access network device, or core network device in the above method embodiments to be implemented.

[0309] Based on the same technical concept, this application also provides a computer program product, which includes a computer program or instructions. When the computer program or instructions are executed by a processor, the methods executed by the terminal device, access network device or core network device in the above method embodiments are implemented.

[0310] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0311] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0312] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0313] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

Claims

1. A communication method, characterized in that, Applied to target access network devices, including: Receive a first request message from a source access network device, wherein the first request message is used to request configuration information of at least one candidate cell of the terminal device, the first request message includes first information, the first information being used to indicate that a first protocol layer function is provided by the source access network device; A first confirmation message is sent to the source access network device, wherein the first confirmation message includes the first configuration information of the at least one candidate cell.

2. The method according to claim 1, characterized in that, The first request message also includes information about a first radio bearer to be established, wherein the information about the first radio bearer to be established is used to generate the first configuration information, and the first configuration information is configuration information related to the second protocol layer function.

3. The method according to claim 2, characterized in that, The second protocol layer functions include one or more of the following: Radio Link Control (RLC) layer functions, Media Access Control (MAC) layer functions, and Physical PHY layer functions.

4. The method according to claim 2 or 3, characterized in that, The information of the first radio bearer to be established includes one or more of the following: the Quality of Service (QoS) information of the first radio bearer to be established; the tunnel information of the first radio bearer to be established; The identification information of the first wireless bearer to be established.

5. The method according to any one of claims 1-4, characterized in that, The first confirmation message also includes information about the established first radio bearer, wherein the information about the established first radio bearer is used to generate second configuration information for the at least one candidate cell, and the second configuration information is configuration information related to the first protocol layer function.

6. The method according to any one of claims 1-5, characterized in that, The first protocol layer function includes one or more of the following: Radio Resource Control (RRC) layer function, Service Data Adaptation Protocol (SDAP) layer function, and Packet Data Convergence Protocol (PDCP) layer function.

7. The method according to any one of claims 1-6, characterized in that, The first request message also includes: The terminal device's preferred configuration information; and / or, The RRC version information of the source access network device.

8. The method according to any one of claims 1-7, characterized in that, The method further includes: Send second information to the source access network device, wherein the second information includes information about neighboring cells of the cell managed by the target access network device, the second information is used to generate second configuration information for the at least one candidate cell, and the second configuration information is configuration information related to the first protocol layer function.

9. The method according to any one of claims 1-8, characterized in that, The target access network device is a target centralized unit (CU); the method further includes: The target CU sends a second request message to the target distributed unit DU, wherein the target DU is used to provide the at least one candidate cell, and the second request message includes: the first information; and / or, information of the first radio bearer to be established, wherein the information of the first radio bearer to be established is used to generate the first configuration information, and the first configuration information is configuration information related to the second protocol layer function; The target CU receives a second confirmation message from the target DU, wherein the second confirmation message includes: the first configuration information; and / or, information of an established first radio bearer, the information of the established first radio bearer being used to generate second configuration information for the at least one candidate cell, and the second configuration information being configuration information related to the first protocol layer function.

10. The method according to any one of claims 1-9, characterized in that, The method further includes: Receive a third request message from the source access network device, wherein the third request message is used to indicate that the first protocol layer function is provided by the target access network device; A third confirmation message is sent to the source access network device, wherein the third confirmation message includes third configuration information and fourth configuration information of the at least one candidate cell, the third configuration information being configuration information related to the second protocol layer function, and the fourth configuration information being configuration information related to the first protocol layer function.

11. The method according to any one of claims 1-9, characterized in that, The method further includes: Send a first indication message to the source access network device; wherein the first indication message is used to indicate that the first protocol layer function is provided by the target access network device, and the first indication message includes third configuration information and fourth configuration information of the at least one candidate cell, the third configuration information being configuration information related to the second protocol layer function, and the fourth configuration information being configuration information related to the first protocol layer function.

12. The method according to claim 11, characterized in that, The target access network device is a target CU; the method further includes: A second indication message is received from a target DU, wherein the target DU is used to provide the at least one candidate cell, and the second indication message is used to indicate that the first protocol layer function is provided by the target DU.

13. The method according to any one of claims 10-12, characterized in that, The target access network device is a target CU; the method further includes: A fourth request message is sent to the target DU, wherein the target DU is used to provide the at least one candidate cell, and the fourth request message includes: third information, the third information being used to indicate that the first protocol layer function is provided by the target access network device; and / or, information of a second radio bearer to be established, the information of the second radio bearer to be established being used to generate the third configuration information; Receive a fourth confirmation message from the target DU, wherein the fourth confirmation message includes the third configuration information and / or information of the established second radio bearer, the information of the established second radio bearer being used to generate the fourth configuration information.

14. A communication method, characterized in that, Applied to source access network devices, including: Send a first request message to the target access network device, wherein the first request message is used to request configuration information of at least one candidate cell of the terminal device, and the first request message includes first information, which is used to indicate that a first protocol layer function is provided by the source access network device; Receive a first confirmation message from the target access network device, wherein the first confirmation message includes first configuration information of the at least one candidate cell.

15. The method according to claim 14, characterized in that, The first request message also includes information about a first radio bearer to be established, wherein the information about the first radio bearer to be established is used to generate the first configuration information, and the first configuration information is configuration information related to the second protocol layer function.

16. The method according to claim 15, characterized in that, The second protocol layer functions include one or more of the following: Radio Link Control (RLC) layer functions, Media Access Control (MAC) layer functions, and Physical PHY layer functions.

17. The method according to claim 15 or 16, characterized in that, The information of the first radio bearer to be established includes one or more of the following: the Quality of Service (QoS) information of the first radio bearer to be established; the tunnel information of the first radio bearer to be established; The identification information of the first wireless bearer to be established.

18. The method according to any one of claims 14-17, characterized in that, The first confirmation message also includes information about the established first radio bearer, wherein the information about the established first radio bearer is used to generate second configuration information for the at least one candidate cell, and the second configuration information is configuration information related to the first protocol layer function.

19. The method according to any one of claims 14-18, characterized in that, The first protocol layer function includes one or more of the following: Radio Resource Control (RRC) layer function, Service Data Adaptation Protocol (SDAP) layer function, and Packet Data Convergence Protocol (PDCP) layer function.

20. The method according to any one of claims 14-19, characterized in that, The first request message also includes: The terminal device's preferred configuration information; and / or, The RRC version information of the source access network device.

21. The method according to any one of claims 14-20, characterized in that, The method further includes: The system receives second information from the target access network device, wherein the second information includes information about neighboring cells of the cell managed by the target access network device, and the second information is used to generate second configuration information for the at least one candidate cell, wherein the second configuration information is configuration information related to the first protocol layer function.

22. The method according to any one of claims 14-21, characterized in that, The method further includes: Send the first configuration information to the terminal device, wherein the first configuration information is used to indicate that the first protocol layer function is provided by the source access network device; or... The terminal device is sent the first configuration information and the second configuration information of the at least one candidate cell, wherein the second configuration information is configuration information related to the first protocol layer function, and the second configuration information is used to indicate that the first protocol layer function is provided by the source access network device.

23. The method according to any one of claims 14-22, characterized in that, The method further includes: Send a third request message to the target access network device, wherein the third request message is used to indicate that the first protocol layer function is provided by the target access network device; A third confirmation message is received from the target access network device, wherein the third confirmation message includes third configuration information and fourth configuration information of the at least one candidate cell, the third configuration information being configuration information related to the second protocol layer function, and the fourth configuration information being configuration information related to the first protocol layer function.

24. The method according to any one of claims 14-22, characterized in that, The method further includes: Receive a first indication message from the target access network device; wherein the first indication message is used to indicate that the first protocol layer function is provided by the target access network device, the first indication message includes third configuration information and fourth configuration information of the at least one candidate cell, the third configuration information is configuration information related to the second protocol layer function, and the fourth configuration information is configuration information related to the first protocol layer function.

25. A communication device, characterized in that, The communication device includes a module for performing the method as described in any one of claims 1 to 13, or a module for performing the method as described in any one of claims 14 to 24.

26. A communication device, characterized in that, The communication device includes a processor for performing the method as described in any one of claims 1 to 13, or the method as described in any one of claims 14 to 24.

27. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program that, when run on a computer, causes the method as described in any one of claims 1 to 13 to be performed, or causes the method as described in any one of claims 14 to 24 to be performed.

28. A computer program product, characterized in that, The computer program product includes a computer program that, when run on a computer, causes the method as described in any one of claims 1 to 13 to be performed, or causes the method as described in any one of claims 14 to 24 to be performed.

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