Wireless communication method, terminal device, and network device

Abstract

The present application provides a wireless communication method, a terminal device, and a network device. The method includes: after the terminal device successfully accesses a first cell, the terminal device performs a layer 2 reset; wherein the first cell is the target cell for layer 2 handover. It can be seen therefrom that in the case where the terminal device fails to access the first cell, the terminal device may not perform a layer 2 reset. Therefore, even if the access to the first cell fails and the terminal device successfully accesses a second cell, if the second cell is a cell that does not require a layer 2 reset, the terminal device may not perform a layer 2 reset, thereby avoiding unnecessary layer 2 resets, reducing packet retransmissions caused by handovers, and further improving the experience of handover users.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and more particularly, to a wireless communication method, a terminal device, and a network device. Background Art

[0002] In the related art, the handover process must perform a layer 2 (L2) reset, and the packet data convergence protocol (PDCP) is used as an anchor point to achieve continuous transmission of service data before and after handover. Among them, the L2 reset may include clearing the radio link control (RLC) buffer. With the development of technologies, some communication systems have realized the separation of the central unit (CU) and the distributed unit (DU). One CU can manage multiple DUs. Therefore, there may be a situation where the DU does not change before and after cell handover. If the DU does not change before and after handover, the L2 reset may not be performed. Based on this, to reduce the latency caused by the handover process, some communication systems have introduced a bottom-layer handover (also known as layer 1 (L1) / L2 handover) process to achieve fast handover. Summary of the Invention

[0003] This application provides a wireless communication method, a terminal device, and a network device. The following introduces each aspect involved in this application.

[0004] In a first aspect, a wireless communication method is provided. The method includes: after the terminal device successfully accesses a first cell, the terminal device performs an L2 reset; where the first cell is the target cell of the bottom-layer handover.

[0005] In a second aspect, a wireless communication method is provided. The method includes: the network device sends first information to the terminal device; where the first information is used to indicate: in the case where the terminal device hands over to the first cell, whether the terminal device needs to perform an L2 reset, and in the case where the terminal device needs to perform an L2 reset, the L2 reset is performed after the terminal device successfully accesses the first cell.

[0006] In a third aspect, a terminal device is provided, characterized in that the terminal device includes: an execution unit, configured to perform an L2 reset after the terminal device successfully accesses a first cell; where the first cell is the target cell of the bottom-layer handover.

[0007] In a fourth aspect, a network device is provided. The network device includes: a sending unit configured to send first information to a terminal device; wherein the first information is used to indicate whether the terminal device needs to perform a layer 2 reset when the terminal device switches to a first cell, and when the terminal device needs to perform a layer 2 reset, the layer 2 reset is performed after the terminal device successfully accesses the first cell.

[0008] In a fifth aspect, a terminal device is provided, including a processor and a memory, the memory is configured to store one or more computer programs, and the processor is configured to call the computer programs in the memory to cause the terminal device to perform some or all of the steps in the method of the first aspect.

[0009] In a sixth aspect, a network device is provided, including a processor, a memory, and a transceiver, the memory is configured to store one or more computer programs, and the processor is configured to call the computer programs in the memory to cause the network device to perform some or all of the steps in the method of the second aspect.

[0010] In a seventh aspect, an embodiment of the present application provides a communication system, which includes the above-mentioned terminal device and / or network device. In another possible design, the system may further include other devices that interact with the terminal device or the network device in the solution provided by the embodiment of the present application.

[0011] In an eighth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program, and the computer program causes the terminal device and / or the network device to perform some or all of the steps in the methods of the above-mentioned aspects.

[0012] In a ninth aspect, an embodiment of the present application provides a computer program product, wherein the computer program product includes a non-transitory computer-readable storage medium storing a computer program, and the computer program is operable to cause the terminal device and / or the network device to perform some or all of the steps in the methods of the above-mentioned aspects. In some implementations, the computer program product may be a software installation package.

[0013] In a tenth aspect, an embodiment of the present application provides a chip, which includes a memory and a processor, and the processor can call and run a computer program from the memory to implement some or all of the steps described in the methods of the above-mentioned aspects.

[0014] The technical solution provided by this application can avoid unnecessary Layer 2 resets, and the specific analysis is as follows. If the terminal device performs a Layer 2 reset before accessing the first cell, and the terminal device fails to access the first cell, then in the case where the terminal device successfully accesses a second cell that does not require a Layer 2 reset, the previously performed Layer 2 reset is unnecessary. This is because the second cell does not require a Layer 2 reset, that is, the terminal device and the second cell can continue to transmit data using the data in the previous RLC buffer. However, since the RLC buffer has been cleared before attempting to access the first cell, even if the terminal device receives the RLC status report sent by the second cell, the terminal device cannot continue to transmit data to the RLC of the second cell. Based on this application, the terminal device will perform a Layer 2 reset only after successfully accessing the first cell. In other words, in the case of failing to access the first cell, the terminal device will not perform a Layer 2 reset. Therefore, even if the terminal device fails to access the first cell and successfully accesses the second cell, the terminal device can not perform a Layer 2 reset according to the situation of the second cell, thus avoiding unnecessary Layer 2 resets, reducing the packet retransmission caused by handover, and further improving the experience of handover users. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of a wireless communication system to which the embodiments of this application are applied.

[0016] Figure 2 is an example diagram of protocol stack entities corresponding to 4 data bearers.

[0017] Figure 3 is an example diagram of the process of Layer 2 handover.

[0018] Figure 4 is a schematic flowchart of a wireless communication method provided by the embodiments of this application.

[0019] Figure 5 is a schematic flowchart of another wireless communication method provided by the embodiments of this application.

[0020] Figure 6 is a schematic structural diagram of a terminal device provided by the embodiments of this application.

[0021] Figure 7 is a schematic structural diagram of a network device provided by the embodiments of this application.

[0022] Figure 8 is a schematic structural diagram of a device for communication provided by the embodiments of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The technical solutions in this application will be described below with reference to the accompanying drawings.

[0024] Communication system

[0025] Figure 1 is the wireless communication system 100 to which the embodiments of the present application are applied. The wireless communication system 100 may include communication devices. The communication devices may include a network device 110 and a terminal device 120. The network device 110 may be a device that communicates with the terminal device 120.

[0026] Figure 1 Exemplarily, one network device and two terminals are shown. Optionally, the wireless communication system 100 may include multiple network devices and the coverage range of each network device may include other numbers of terminal devices, which is not limited in the embodiments of the present application.

[0027] Optionally, the wireless communication system 100 may further include other network entities such as a network controller, a mobility management entity, etc., which is not limited in the embodiments of the present application.

[0028] It should be understood that the technical solutions of the embodiments of the present application can be applied to various communication systems, such as: the fifth generation (5G) system or new radio (NR), long term evolution (LTE) system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD), etc. The technical solutions provided by the present application can also be applied to future communication systems, such as the sixth generation mobile communication system, or a satellite communication system, and so on.

[0029] The terminal device in the embodiments of the present application may also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station (MS), mobile terminal (MT), remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device. The terminal device in the embodiments of the present application may be a device that provides voice and / or data connectivity to users and can be used to connect people, things, and machines. For example, it can be a handheld device with wireless connection capabilities, in-vehicle device, etc. The terminal device in the embodiments of the present application may be a mobile phone, tablet computer (Pad), laptop computer, palmtop computer, mobile internet device (MID), wearable device, virtual reality (VR) device, augmented reality (AR) device, wireless terminal in industrial control, wireless terminal in self-driving, wireless terminal in remote medical surgery, wireless terminal in smart grid, wireless terminal in transportation safety, wireless terminal in smart city, wireless terminal in smart home, etc. Optionally, the UE can be used as a base station. For example, the UE can act as a scheduling entity that provides sidelink signals between UEs in vehicle-to-everything (V2X) or device-to-device (D2D), etc. For instance, a cellular phone and a car communicate with each other using sidelink signals. A cellular phone and a smart home device communicate without relaying the communication signal through a base station.

[0030] The network device in the embodiments of the present application can be a device for communicating with a terminal device. The network device can also include an access network device. The access network device can provide communication coverage for a specific geographical area and can communicate with a terminal device 120 located within the coverage area. The access network device can also be referred to as a radio access network (RAN) node (or device) that connects the terminal device to a wireless network. The access network device can generally cover various names as follows, or be replaced with the following names, such as: Node B, evolved Node B (eNB), next generation Node B (gNB), relay station, access point, transmitting and receiving point (TRP), transmitting point (TP), master eNB (MeNB), secondary eNB (SeNB), multi-standard radio (MSR) node, home base station, network controller, access node, wireless node, access point (AP), transmission node, transceiver node, base band unit (BBU), remote radio unit (RRU), active antenna unit (AAU), remote radio head (RRH), CU, DU, positioning node, etc. The base station can be a macro base station, micro base station, relay node, donor node or the like, or a combination thereof. The base station can also refer to a communication module, modem or chip used to be disposed in the foregoing device or apparatus. The base station can also be a mobile switching center and a device that undertakes the base station function in D2D, V2X, machine-to-machine (M2M) communication, a network-side device in a 6G network, a device that undertakes the base station function in a future communication system, etc. The base station can support networks with the same or different access technologies. The embodiments of the present application do not limit the specific technologies and specific device forms adopted by the access network device.

[0031] The base station can be fixed or mobile. For example, a helicopter or a drone can be configured to act as a mobile base station, and one or more cells can move according to the position of the mobile base station. In other examples, a helicopter or a drone can be configured to be a device for communicating with another base station.

[0032] The communication devices involved in a wireless communication system may include not only access network devices and terminal devices, but also core network elements. The core network elements can be implemented by devices, that is, the core network elements are core network devices. It can be understood that the core network devices can also be a type of network device.

[0033] The core network elements in the embodiments of the present application may include elements that process and forward signaling and data of users. For example, the core network devices may include core access and mobility management function (AMF), session management function (SMF), as well as core network devices such as user plane gateway, location management function (LMF), etc. Among them, the user plane gateway can be a server with functions such as mobility management, routing, and forwarding of user plane data, generally located on the network side, such as serving gateway (SGW), packet data network gateway (PGW), or user plane function entity (UPF), etc. Of course, other elements may also be included in the core network, which are not listed one by one here.

[0034] In some deployments, the network devices in the embodiments of the present application may refer to CU or DU, or the network devices include CU and DU. The gNB may also include AAU.

[0035] The network devices and terminal devices can be deployed on land, including indoor or outdoor, handheld or vehicle-mounted; they can also be deployed on water; they can also be deployed on airplanes, balloons, and satellites in the air. The scenarios where the network devices and terminal devices are located in the embodiments of the present application are not limited.

[0036] It should be understood that all or part of the functions of the communication devices in the present application can also be implemented by software functions running on hardware, or by virtualized functions instantiated on a platform (such as a cloud platform).

[0037] CU and DU separation architecture

[0038] Some wireless communication networks (such as 5G communication networks) have realized the separation of CU and DU. One CU can manage multiple DUs. For example, one CU can manage hundreds or thousands of DUs.

[0039] From the perspective of the communication protocol stack, the control plane entity is in the CU, and the user plane entity is in the CU and the DU. Specifically for the user plane entity, the CU contains the service data adaptation protocol (SDAP) and the packet data convergence protocol (PDCP), and the DU contains the RLC, medium access control (MAC), and physical layer (PHY). Figure 2 It is an example diagram of protocol stack entities corresponding to 4 data bearers. Different fillings represent protocol stack entities corresponding to 4 data bearers respectively.

[0040] For the CU and DU separation architecture, the cell handover process of the terminal device can be divided into the following three cases (Case 1 to Case 3).

[0041] Case 1: Handover without changing the DU.

[0042] For Case 1, before and after the handover, the DU serving the terminal device does not change, and the CU does not change either. For the handover without changing the DU, the RLC entities before and after the handover are in the same DU. Refer to Figure 2 , the RLC entities corresponding to data bearer 1 and data bearer 2 are both in the same DU. Therefore, for Case 1, the terminal device may not need to perform RLC reset (or called layer 2 reset) after the handover.

[0043] Case 2: Handover without changing the CU.

[0044] For Case 2, before and after the handover, the DU serving the terminal device changes, and the CU does not change. For the handover without changing the CU, the RLC entities before and after the handover are in different DUs. Continuing to refer to Figure 2 , the RLC entities corresponding to data bearer 3 and data bearer 4 are in different DUs. Therefore, for Case 2, the terminal device needs to reset the RLC after the handover. And since the CU does not change, the PDCP does not need to be reset. It can be seen that the handover without changing the CU is essentially similar to the in-station handover in some communication systems (such as the intra eNB handover in LTE).

[0045] Case 3: Handover with changing the CU.

[0046] For Case 3, before and after the handover, the DU serving the terminal device changes, and the CU changes. For the handover with CU replacement, the RLC entities before and after the handover are not in the same DU, so the RLC needs to be reset. Also, since the PDCPs before and after the handover are not in the same CU, the PDCP needs to be re-established in the target CU through the interaction between the CUs. It can be seen that the handover with CU replacement is essentially similar to the inter-station handover in some communication systems (such as the inter eNB handover in LTE).

[0047] In the related art, the handover process must perform a layer 2 reset or an RLC reset, and use the PDCP as an anchor point to achieve continuous transmission of service data before and after the handover. However, according to the above analysis, if the DU does not change before and after the handover, the RLC actually does not need to be reset. Therefore, to reduce the latency caused by the handover process, some communication systems have introduced a bottom-layer handover process to achieve fast handover. The following will describe the bottom-layer handover in combination with Figure 3 illustrate the bottom-layer handover.

[0048] Underlying handover

[0049] The bottom-layer handover can also be referred to as layer 1 (L1) / layer 2 (L2) handover.

[0050] Figure 3 is a schematic flowchart of a bottom-layer handover. In Figure 3 , the source cell prepares three alternative target cells for the terminal device: Target Cell 1, Target Cell 2, and Target Cell 3.

[0051] Figure 3 The bottom-layer handover process shown includes steps S310 to S340.

[0052] Step S310, the source cell and each alternative target cell perform handover preparation.

[0053] Step S310 may include steps S311 to S316.

[0054] Step S311, the source cell sends a handover preparation message to Target Cell 1.

[0055] Step S312, Target Cell 1 sends a handover preparation completion message to the source cell.

[0056] Step S313, the source cell sends a handover preparation message to Target Cell 2.

[0057] Step S314, Target Cell 2 sends a handover preparation completion message to the source cell.

[0058] Step S315, the source cell sends a handover preparation message to Target Cell 3.

[0059] Step S316, the target cell 3 feeds back a handover preparation completion message to the source cell.

[0060] Step S320, the source cell sends a handover configuration message to the terminal device. This handover configuration message is transmitted through radio resource control (RRC) signaling.

[0061] The handover configuration message may include the configuration information of all alternative target cells (target cell 1 to target cell 3).

[0062] Step S330, the terminal device performs timing advance (TA) pre-acquisition and measurement.

[0063] The terminal device may send preambles to each alternative target cell respectively to obtain the TA. Among them, the TA may be notified to the terminal device by each target cell; or, each target cell may not notify the terminal device of the TA, and the TA may be stored by the source cell.

[0064] The terminal device may also measure each alternative target cell to obtain a measurement result.

[0065] Step S340, the terminal device reports the measurement results of each alternative target cell to the source cell.

[0066] The source cell may determine the target cell to which the terminal device needs to hand over according to the measurement results and inform the terminal device through the underlying signaling. Exemplarily, Figure 3 The method shown may include steps S350, S360 or S370.

[0067] If the source cell determines that the terminal device hands over to target cell 1, then Figure 3 The method shown may include step S350.

[0068] Step S350 may include steps S351 to S353.

[0069] Step S351, the source cell sends a handover command to the terminal device through L1 / L2 signaling. The handover command is used to indicate that the terminal device needs to hand over to target cell 1.

[0070] Step S352, the terminal device sends uplink data to target cell 1 and receives a confirm message sent by target cell 1. Thus, the handover process ends.

[0071] Among them, if the terminal device has pre-obtained the TA of target cell 1 and the network device corresponding to target cell 1 allocates a configured grant (CG) to the terminal device, the terminal device can directly send uplink data. If the terminal device has not pre-obtained the TA of target cell 1, or the network device corresponding to target cell 1 does not allocate a CG to the terminal device, the terminal device obtains uplink resources and TA through a random access procedure and sends uplink data.

[0072] If the source cell determines that the terminal device switches to target cell 2, then Figure 3 The method shown may include step S360.

[0073] Step S360 may include steps S361 to S363.

[0074] Step S361, the source cell sends a handover command to the terminal device through L1 / L2 signaling. The handover command is used to indicate that the terminal device needs to switch to target cell 2.

[0075] Step S362, the terminal device sends uplink data to target cell 2 and receives an acknowledgment message sent by target cell 2. Thus, the handover process ends.

[0076] Among them, if the terminal device has pre-obtained the TA of target cell 2 and the network device corresponding to target cell 2 allocates a CG to the terminal device, the terminal device can directly send uplink data. If the terminal device has not pre-obtained the TA of target cell 2, or the network device corresponding to target cell 2 does not allocate a CG to the terminal device, the terminal device obtains uplink resources and TA through a random access procedure and sends uplink data.

[0077] If the source cell determines that the terminal device switches to target cell 3, then Figure 3 The method shown may include step S370.

[0078] Step S370 may include steps S371 to S373.

[0079] Step S371, the source cell sends a handover command to the terminal device through L1 / L2 signaling. The handover command is used to indicate that the terminal device needs to switch to target cell 3.

[0080] Step S372, the terminal device sends uplink data to target cell 3 and receives an acknowledgment message sent by target cell 3. Thus, the handover process ends.

[0081] Among them, if the terminal device has pre-acquired the TA of target cell 3 and the network device corresponding to target cell 3 allocates a CG to the terminal device, the terminal device can directly send uplink data. If the terminal device has not pre-acquired the TA of target cell 3, or the network device corresponding to target cell 3 does not allocate a CG to the terminal device, the terminal device obtains uplink resources and TA through a random access procedure and sends uplink data.

[0082] In Figure 3 In the method shown, if the terminal device switches to target cell 1, it belongs to a handover without replacing the DU; if the terminal device switches to target cell 2, it belongs to a handover with replacing the DU; if the terminal device switches to target cell 3, it belongs to a handover with replacing the CU. Therefore, if the terminal device switches into target cell 1, the terminal device does not need to perform an L2 reset; if the terminal device switches into target cell 2 or target cell 3, an L2 reset is required.

[0083] Figure 3 shows the underlying handover process in which the source cell determines which alternative target cell the terminal device will switch to. Similarly, the underlying handover can also be applied in the conditional handover process. Similar to Figure 3 the process shown, in the conditional handover process, the terminal device can pre-acquire the configuration information of one or more quasi-target cells and select a target cell to switch into by itself according to the measurement results.

[0084] It should be noted that in the conditional handover process, if multiple quasi-target cells are pre-configured and the terminal device selects to access target cell 2 but the access fails, the terminal device can select another quasi-target cell (such as target cell 3) to access again. In this case, whether the terminal device switches into target cell 2 or target cell 3, an L2 reset is required.

[0085] This application optimizes the underlying handover process. Figure 4 is a schematic structural diagram of a wireless communication method provided by an embodiment of this application.

[0086] Figure 4 The method shown can be executed by a terminal device. Figure 4 The method shown includes step S410.

[0087] Step S410, after the terminal device successfully accesses the first cell, the terminal device performs an L2 reset.

[0088] The first cell can be the target cell for layer 2 handover. For example, the first cell can be the target cell indicated by the handover command sent by the network device. That is to say, the first cell can be the target cell determined by the network device. Alternatively, the first cell can be the target cell selected by the terminal device itself during the conditional handover process. That is to say, the first cell can be the target cell determined by the terminal device itself.

[0089] As described above, the layer 2 reset performed by the terminal device can be understood as the reset of RLC. The reset of RLC can refer to clearing the RLC buffer. For example, the layer 2 reset can include: clearing the sender RLC buffer; and / or, clearing the receiver RLC buffer.

[0090] It can be seen from step S410 that the terminal device will perform a layer 2 reset only after successfully accessing the first cell. In other words, in the case where the terminal device fails to access the first cell, the terminal device may not perform a layer 2 reset.

[0091] This technical solution can avoid unnecessary layer 2 resets, and the specific analysis is as follows. If the terminal device performs a layer 2 reset before accessing the first cell and fails to access the first cell, then in the case of successfully accessing another second cell that does not require a layer 2 reset, the previously performed layer 2 reset is unnecessary. This is because the second cell does not require a layer 2 reset, that is, the terminal device and the second cell can continue to interact using the data in the previous RLC buffer. However, since the RLC buffer has been cleared before attempting to access the first cell, it is difficult for the RLC between the terminal device and the second cell to continue transmitting data or data needs to be retransmitted. For example, for uplink transmission, the RLC status report sent by the second cell can indicate that the second cell requests the retransmission of some RLC service data units (SDUs). If the RLC buffer is not cleared, the terminal device can find these RLC SDUs from the RLC buffer and retransmit them to the second cell. However, in the case where the RLC buffer is cleared, the terminal device cannot find these RLC SDUs from the RLC buffer and cannot transmit these RLC SDUs. Another example is for downlink transmission. If the layer 2 reset is not performed, the terminal device can send an RLC status report to the second cell and request the retransmission of some RLC SDUs or RLSSDU segments, thereby avoiding excessive retransmission of data. However, in the case where the layer 2 reset is performed, excessive retransmission of data cannot be avoided based on this technical solution. Based on the present application, after the terminal device successfully accesses the first cell, the terminal device will perform a layer 2 reset. In other words, in the case of failing to access the first cell, the terminal device will not perform a layer 2 reset. Therefore, even if the access to the first cell fails and the terminal device successfully accesses the second cell, the terminal device can not perform a layer 2 reset according to the situation of the second cell, thereby avoiding unnecessary layer 2 resets, reducing the packet retransmission caused by handover, and further improving the experience of handover users.

[0092] In some embodiments, in the case where the terminal device determines that a layer 2 reset needs to be performed, the terminal device can perform step S410. For example, the terminal device can determine: if it switches to the first cell, whether a layer 2 reset needs to be performed. If a layer 2 reset is not required, the terminal device does not perform a layer 2 reset; if a layer 2 reset is required, the terminal device performs a layer 2 reset (i.e., performs step S410). The terminal device can determine whether a layer 2 reset is required according to the first information in step S405 described below.

[0093] It should be noted that whether to perform Layer 2 reset can be at the cell level. That is, for different cells, the situation of whether the terminal device needs to perform Layer 2 reset can be different. For example, in the case of handover to the first cell where the DU is not replaced, the terminal device does not need to perform Layer 2 reset. Or, in the case of handover to the first cell where the DU is replaced but the CU is not replaced, the terminal device needs to perform Layer 2 reset. Or, in the case of handover to the first cell where the CU is replaced, the terminal device needs to perform Layer 2 reset.

[0094] It should be noted that whether to replace the DU can be one of the conditions for whether to perform (or not perform) Layer 2 reset. The conditions for whether to perform Layer 2 reset can also include other conditions. When some or all of the conditions for whether to perform Layer 2 reset are met, it can be determined that Layer 2 reset needs to be performed; or, when some or all of the conditions for whether to perform Layer 2 reset are met, it can be determined that Layer 2 reset does not need to be performed. For example, in the case of handover to the first cell where the DU is replaced, if the two DUs before and after replacement can achieve storage space sharing through a large-capacity transmission channel or cloud connection, etc., the terminal device may not need to perform Layer 2 reset.

[0095] In some embodiments, Figure 4 The method shown may further include step S405. Step S405 can be executed by the terminal device and the network device. The network device can be the network device corresponding to the source cell of the terminal device.

[0096] Step S405, the network device sends the first information to the terminal device.

[0097] The first information can be used to indicate whether the terminal device needs to perform Layer 2 reset in the case of handover to the first cell.

[0098] According to the first information, the terminal device can determine whether it needs to perform Layer 2 reset in the case of handover to the first cell, so as to determine whether it needs to perform Layer 2 reset after successfully accessing the first cell.

[0099] In some embodiments, the first information can be indicated in an explicit manner.

[0100] Exemplarily, the first information may include a first bit, a first boolean value, or a first enumerated value corresponding to the first cell. For example, when the first bit is 0, it may indicate that no layer 2 reset needs to be performed for handover to the first cell; when the first bit is 1, it may indicate that a layer 2 reset needs to be performed for handover to the first cell. Alternatively, when the first bit is 1, it may indicate that no layer 2 reset needs to be performed for handover to the first cell; when the first bit is 0, it may indicate that a layer 2 reset needs to be performed for handover to the first cell. For another example, when the first boolean value is "true", it may indicate that no layer 2 reset needs to be performed for handover to the first cell; when the first boolean value is "false", it may indicate that a layer 2 reset needs to be performed for handover to the first cell. Alternatively, when the first boolean value is "false", it may indicate that no layer 2 reset needs to be performed for handover to the first cell; when the first boolean value is "true", it may indicate that a layer 2 reset needs to be performed for handover to the first cell. For another example, the first enumerated value may indicate "L2 reset is required" or "L2 reset is not required".

[0101] Exemplarily, for conditional handover, the network device may divide the quasi-target cells into a first group and a second group. The first group may include one or more cells for which an L2 reset needs to be performed; the second group may include one or more cells for which no L2 reset needs to be performed. Among them, the one or more cells may be the quasi-target cells of the terminal device.

[0102] In some embodiments, the first information may be indicated in an implicit manner.

[0103] Exemplarily, the first information may be indicated by the conditional handover condition of the first cell. The terminal device may determine whether an L2 reset needs to be performed for the first cell according to the conditional handover condition configured by the network device for the first cell.

[0104] Optionally, in the case where an L2 reset needs to be performed for the first cell, the network device may set the conditional handover condition of the first cell to a first condition that is relatively difficult to meet; in the case where no L2 reset needs to be performed for the first cell, the network device may set the conditional handover condition of the first cell to a second condition that is relatively easy to meet. Optionally, the first condition may include that the RSRP of the first cell reaches a first value and the first cell meets the conditional handover condition; the second condition may include: the RSRP of the first cell reaches a second value and the first cell meets the conditional handover condition; where the first value is greater than the second value.

[0105] Optionally, for all quasi-target cells, the network device may configure multiple conditional handover conditions; or, for quasi-target cells in frequency range (FR) 1, configure multiple handover conditions; or, for quasi-target cells in FR2, configure multiple handover conditions. Among them, the multiple handover conditions may be related to the first information. For example, the multiple handover conditions may include the first condition and the second condition described above.

[0106] Exemplarily, the first information may indicate whether the terminal device needs to perform a layer 2 reset through the order of the first cell among multiple cells. The multiple cells may be the cells that the terminal device can attempt to perform a lower layer handover. For example, the multiple cells may be represented by a cell list. For the cells in the cell list, the first half may be the cells that do not need to perform an L2 reset, and the second half may be the cells that need to perform an L2 reset. Or, for the cells in the cell list, the first half may be the cells that need to perform an L2 reset, and the second half may be the cells that do not need to perform an L2 reset.

[0107] In some embodiments, the network device may send second information to the terminal device. The second information may include information about multiple cells. The multiple cells may be the cells that the terminal device can attempt to perform a lower layer handover.

[0108] As can be seen from the above, in the lower layer handover process, the network device or the terminal device may determine the target cell for handover according to the L1 / L2 measurement result of the terminal device. Since the L1 / L2 measurement result is not smoothed and filtered, the fluctuation is large. The handover failure probability based on the L1 / L2 measurement result is relatively high. If the network device only indicates one cell that the terminal device can attempt to perform a lower layer handover to the terminal device (for example, the technical solution in the handover command in the related art only includes one cell), then after the handover fails in this cell, the terminal device can only perform cell reselection and initiate a radio link reestablishment. This will result in a reduction in the handover success rate and a relatively long data transmission interruption time. Based on the present application, the terminal device can sequentially attempt to handover to multiple cells indicated by the second information, thereby improving the handover success rate and reducing the data transmission interruption time.

[0109] In some embodiments, the second information may be carried in the handover command. That is to say, the handover command may include multiple cells. All of the multiple cells may be the cells that the terminal device can perform an L1 / L2 handover. The multiple cells indicated by the handover command may all meet the handover conditions. That is to say, the L / L2 measurement results of the multiple cells indicated by the handover command all meet the handover requirements.

[0110] In some embodiments, the second information may be carried in the handover configuration message. In other words, the terminal device may initiate a random access to a cell indicated in a handover configuration message. Since the alternative target cells indicated in the handover configuration message are the cells that have interacted with the source cell, when the terminal device accesses the alternative target cells indicated in the handover configuration message, it can also be processed according to the handover process. Continue to refer to Figure 3The scene shown. Based on the present application, the target cell 1, target cell 2, and target cell 3 included in the handover configuration message in step S320 can all be cells that the terminal device can attempt to hand over to. This is because, in step S310, a handover preparation process is performed between the source cell and target cell 1, target cell 2, and target cell 3.

[0111] In some embodiments, the second information can be carried in a handover indication. The handover indication can be an L1 / L2 signaling. The handover indication can be used to indicate one or more target cells.

[0112] It should be noted that the second information can be carried alone in a handover command, or can be carried in at least two of a handover command, a handover configuration message, and a handover indication.

[0113] In the case where the second information is carried alone in a handover command, the handover command can indicate multiple cells. If the terminal device fails to access all the multiple cells indicated by the handover command, the terminal device can perform cell reselection and perform RRC reestablishment.

[0114] In the case where the second information is carried in a handover command and a handover configuration message, the handover command can indicate one or more cells, and the handover configuration message can indicate one or more cells. All the cells indicated in the handover command and the handover configuration message can form the multiple cells indicated by the second information. For example, the handover command can include only one cell. The terminal device can preferentially attempt to access the cell indicated in the handover command. In the case where the access to the cell indicated in the handover command fails, the terminal device can select a cell that has been indicated in the handover configuration message but not included in the handover command, and initiate a random access for the selected cell. Or, the handover command can include multiple cells. The terminal device can preferentially attempt to access the multiple cells indicated by the handover command. In the case where the access to all the multiple cells indicated in the handover command fails, the terminal device can select a cell that has been indicated in the handover configuration message but not included in the handover command, and initiate a random access for the selected cell.

[0115] The following takes Figure 5 as an example for illustration. Figure 5 The method shown includes step S510 and step S520.

[0116] Step S510, the network device sends a handover configuration message to the terminal device.

[0117] The handover configuration message indicates 5 cells. The 5 cells are respectively: cell A, cell B, cell C, cell D, and cell E.

[0118] Step S520, the network device sends a handover command to the terminal device.

[0119] The handover command indicates three cells. The three cells are Cell B, Cell C, and Cell E respectively.

[0120] For Figure 5 For the scenario shown, when the terminal device fails to access Cell B, Cell C, and Cell E, the terminal device can perform cell reselection and perform RRC re - establishment. Alternatively, when the terminal device fails to access Cell B, Cell C, and Cell E, the terminal device can attempt to access Cell A or Cell D.

[0121] Optionally, in step S520, the handover command can indicate only one cell. For example, the one cell indicated by the handover command can be Cell B. When the terminal device fails to access Cell B, the terminal device can attempt to access Cell A, Cell C, Cell D, or Cell E.

[0122] It should be noted that for the multiple cells indicated by the second piece of information, when the terminal device calculates the handover parameters, it can calculate separately or calculate together with the cells in the related technology. Among them, the handover parameters can include one or more of the following: the number of handovers, handover delay, etc., statistical information. For example, for the multiple cells indicated by the second piece of information, the statistical information can include one or more of the following: the probability of successfully handing over to the first cell among the multiple cells, the number of times of successfully handing over to the first cell among the multiple cells, the frequency of successfully handing over to the first cell among the multiple cells, the probability of successfully handing over to a non - first cell among the multiple cells, the number of times of successfully handing over to a non - first cell among the multiple cells, the frequency of successfully handing over to a non - first cell among the multiple cells. Another example is that the statistical information can include one or more of the following: the number of times of successfully handing over to a cell that does not require layer 2 reset among the multiple cells, the probability of successfully handing over to a cell that does not require layer 2 reset among the multiple cells, the frequency of successfully handing over to a cell that does not require layer 2 reset among the multiple cells, the number of times of successfully handing over to a cell that requires layer 2 reset among the multiple cells, the probability of successfully handing over to a cell that requires layer 2 reset among the multiple cells, the frequency of successfully handing over to a cell that requires layer 2 reset among the multiple cells.

[0123] The terminal device can attempt to access the multiple cells indicated by the second piece of information in a certain order. The following describes the access order of the terminal device to the multiple cells.

[0124] In some embodiments, the multiple cells indicated by the second information may form a cell list. The terminal device may access the corresponding cells in sequence according to the order of the cell list. That is to say, the terminal device may first attempt to access the first cell in the cell list; if the access to the first cell fails, the terminal device may attempt to access the second cell in the cell list; if the access to the second cell fails, the terminal device may attempt to access the third cell in the cell list... until attempting to access the last cell in the cell list. Continuing to refer to Figure 5 , taking the example that the second information is only carried in the handover command, the terminal device may attempt to access in the order of cell B, cell C, and cell E. That is to say, the terminal device may first attempt to access cell B; if the access to cell B fails, the terminal device may attempt to access cell C; if the access to cell C fails, the terminal device may attempt to access cell E.

[0125] In some embodiments, the terminal device may preferentially attempt to handover to the cell with a higher priority among the multiple cells indicated by the second information. For example, in the case where the priority associated with the first cell is higher than or equal to the priority associated with the second cell, the terminal device may first attempt to access the first cell. If the access to the first cell fails, the terminal device may attempt to access the second cell.

[0126] The priority associated with the first cell may be determined according to one or more of the following information: whether layer 2 reset needs to be performed for handover to the first cell, the signal strength of the first cell, and the order of the first cell among the multiple cells included in the second information.

[0127] For example, the priority associated with a cell that does not require layer 2 reset may be higher than the priority associated with a cell that requires layer 2 reset. That is to say, the terminal device may, according to the principle of "first attempt to access the cell that does not require layer 2 reset", first attempt to access the cell that does not require layer 2 reset, and then attempt to access the cell that requires layer 2 reset. Continuing to refer to Figure 5 , if cell B and cell E are cells that do not require layer 2 reset, and cell C is a cell that requires layer 2 reset, the terminal device may attempt to access in the order of cell B, cell E, and cell C.

[0128] For another example, the priority associated with a cell with a higher signal strength may be higher than the priority associated with a cell with a lower signal strength. That is to say, the terminal device may attempt to access one by one from the cell with a strong signal strength to the cell with a weak signal strength according to the measured signal strength.

[0129] For another example, among the multiple cells included in the second information, the priority associated with the cell with a higher order may be higher than the priority associated with the cell with a lower order. That is to say, the terminal device may attempt to access in the order of the multiple cells included in the second information.

[0130] The above embodiments can be implemented independently or in combination. For example, when the priorities of two cells are the same, the terminal device can attempt to access according to the order of the two cells in the cell list.

[0131] In some embodiments, the terminal device may send third information to the network device. The third information may be used to indicate that the terminal device has not performed a layer 2 reset before attempting to access the first cell. Alternatively, the third information is used to indicate that the terminal device has not performed a layer 2 reset before successfully accessing the first cell.

[0132] Exemplarily, the third information may be carried in one or more of the following: RLC status report, media access control control element (MAC CE), RRC message, message 3 (msg3). When the third information is carried in the MAC CE, the third information may be carried in one or more bits in the MAC sub-header. When the third information is carried in the RRC message, the third information may be carried in a certain parameter in the RRC message. When the third information is carried in msg3, the third information indicated by the physical layer may be transmitted by means of physical layer puncturing within msg3.

[0133] It should be noted that when the third information is carried in the RLC status report, through the RLC status report, the terminal device can not only inform the network device that it has not performed a layer 2 reset before attempting to access the first cell, but also inform the network device of the RLC situation of the terminal device.

[0134] For example, if the terminal device has obtained the CG resources allocated by the first cell and has obtained the TA, when the terminal device attempts to access the first cell, it can send an RLC status report. If the terminal device successfully accesses the first cell and the network device knows that the terminal device needs to perform a layer 2 reset during this handover process, the network device can ignore the RLC status report. After performing the layer 2 reset, the PDCP layer can ensure the continuous transmission of data packets. If the terminal device fails to access the first cell, the terminal device may not perform a layer 2 reset and continue to search for the next cell to attempt access.

[0135] The method embodiments of the present application have been described in detail above. Next, the device embodiments of the present application will be described in detail. It should be understood that the description of the method embodiments corresponds to the description of the device embodiments. Therefore, the parts not described in detail can be referred to the previous method embodiments.

[0136] Figure 6 It is a schematic structural diagram of a terminal device 600 provided by an embodiment of the present application. The terminal device 600 includes an execution unit 610.

[0137] The execution unit 610 is configured to perform a layer 2 reset after the terminal device successfully accesses the first cell; wherein, the first cell is the target cell for layer 2 handover.

[0138] In some embodiments, the execution unit 610 is configured to: when the terminal device determines that a layer 2 reset needs to be performed, the terminal device performs a layer 2 reset.

[0139] In some embodiments, the terminal device 600 is further configured to: receive first information; wherein, the first information is used to indicate whether the terminal device needs to perform a layer 2 reset when switching to the first cell.

[0140] In some embodiments, the first information is indicated by the conditional handover condition of the first cell; and / or, the first information is indicated by the order of the first cell among multiple cells, where the multiple cells are cells that the terminal device can attempt to perform layer 2 handover to.

[0141] In some embodiments, the terminal device 600 is further configured to: receive second information; wherein, the second information includes information of multiple cells, the multiple cells include the first cell, and the multiple cells are cells that the terminal device can attempt to perform layer 2 handover to.

[0142] In some embodiments, the second information is carried in one or more of the following messages: handover configuration message, handover command, handover indication.

[0143] In some embodiments, the cell that the terminal device preferentially attempts to handover to is the cell with a higher priority among the multiple cells.

[0144] In some embodiments, the priority associated with the first cell is determined based on one or more of the following information: whether a layer 2 reset needs to be performed when switching to the first cell; the signal strength of the first cell; the order of the first cell among the multiple cells included in the second information.

[0145] In some embodiments, the terminal device 600 is further configured to: send third information; wherein, the third information is used to indicate that the terminal device has not performed a layer 2 reset before attempting to access the first cell.

[0146] In some embodiments, the third information is carried in one or more of the following: MAC CE, RRC message, message 3, RLC status report.

[0147] In an alternative embodiment, the execution unit 610 may be the processor 810. The terminal device 600 may further include a memory 820 and a transceiver 830, specifically as Figure 8 shown.

[0148] Figure 7This is a network device 700 provided by an embodiment of the present application. The network device 700 includes a sending unit 710.

[0149] The sending unit 710 is configured to send first information to a terminal device; wherein, the first information is used to indicate whether the terminal device needs to perform a layer 2 reset when the terminal device switches to a first cell, and if the terminal device needs to perform a layer 2 reset, the layer 2 reset is performed after successfully accessing the first cell.

[0150] In some embodiments, the first information is indicated by a conditional handover condition of the first cell; and / or, the first information is indicated by the order of the first cell among multiple cells, where the multiple cells are cells that the terminal device can attempt to perform a lower layer handover to.

[0151] In some embodiments, the network device 700 is further configured to: send second information to the terminal device; wherein, the second information includes information of multiple cells, the multiple cells include the first cell, and the multiple cells are cells that the terminal device can attempt to perform a lower layer handover to.

[0152] In some embodiments, the second information is carried in one or more of the following messages: a handover configuration message, a handover command, a handover indication.

[0153] In some embodiments, the cell that the terminal device preferentially attempts to hand over to is the cell with a higher priority among the multiple cells.

[0154] In some embodiments, the priority associated with the first cell is determined based on one or more of the following information: whether a layer 2 reset needs to be performed when switching to the first cell; the signal strength of the first cell; the order of the first cell among the multiple cells included in the second information.

[0155] In some embodiments, the network device 700 is further configured to: receive third information; wherein, the third information is used to indicate that the terminal device has not performed a layer 2 reset before attempting to access the first cell.

[0156] In some embodiments, the third information is carried in one or more of the following: a MAC CE, an RRC message, a message 3, an RLC status report.

[0157] In an alternative embodiment, the sending unit 710 may be a transceiver 830. The network device 700 may further include a processor 810 and a memory 820, specifically as Figure 8 shown.

[0158] Figure 8 This is a schematic structural diagram of a device for communication according to an embodiment of the present application. Figure 8The dashed line therein indicates that the unit or module is optional. The apparatus 800 can be used to implement the method described in the foregoing method embodiments. The apparatus 800 can be a chip, a terminal device, or a network device.

[0159] The apparatus 800 may include one or more processors 810. The processor 810 can support the apparatus 800 to implement the method described in the foregoing method embodiments. The processor 810 can be a general-purpose processor or a dedicated processor. For example, the processor can be a central processing unit (CPU). Alternatively, the processor can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0160] The apparatus 800 may further include one or more memories 820. A program is stored on the memory 820, and the program can be executed by the processor 810, so that the processor 810 executes the method described in the foregoing method embodiments. The memory 820 can be independent of the processor 810 or integrated in the processor 810.

[0161] The apparatus 800 may further include a transceiver 830. The processor 810 can communicate with other devices or chips through the transceiver 830. For example, the processor 810 can perform data transmission and reception with other devices or chips through the transceiver 830.

[0162] An embodiment of the present application further provides a computer-readable storage medium for storing a program. The computer-readable storage medium can be applied to the terminal or network device provided in the embodiments of the present application, and the program enables a computer to execute the methods performed by the terminal or network device in various embodiments of the present application.

[0163] An embodiment of the present application further provides a computer program product. The computer program product includes a program. The computer program product can be applied to the terminal or network device provided in the embodiments of the present application, and the program enables a computer to execute the methods performed by the terminal or network device in various embodiments of the present application.

[0164] An embodiment of the present application further provides a computer program. The computer program can be applied to the terminal or network device provided in the embodiment of the present application, and the computer program enables the computer to execute the methods performed by the terminal or network device in various embodiments of the present application.

[0165] It should be understood that the terms "system" and "network" in the present application can be used interchangeably. In addition, the terms used in the present application are only used to explain specific embodiments of the present application, rather than intended to limit the present application. The terms "first", "second", "third", "fourth", etc. in the specification, claims and drawings of the present application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0166] In the embodiments of the present application, the "indication" mentioned can be a direct indication, an indirect indication, or a representation of an associated relationship. For example, A indicates B, which can mean that A directly indicates B. For example, B can be obtained through A; it can also mean that A indirectly indicates B. For example, A indicates C, and B can be obtained through C; it can also mean that there is an associated relationship between A and B.

[0167] In the embodiments of the present application, "B corresponding to A" means that B is associated with A, and B can be determined according to A. However, it should also be understood that determining B according to A does not mean determining B only according to A. B can also be determined according to A and / or other information.

[0168] In the embodiments of the present application, the term "corresponding" can represent a direct or indirect corresponding relationship between two parties, can also represent an associated relationship between two parties, or can be a relationship such as indication and being indicated, configuration and being configured, etc.

[0169] In the embodiments of the present application, "predefined" or "preconfigured" can be implemented by pre-saving corresponding codes, tables, or other ways that can be used to indicate relevant information in a device (for example, including a terminal device and a network device). The present application does not limit its specific implementation manner. For example, predefined can refer to what is defined in a protocol.

[0170] In the embodiments of the present application, the "protocol" can refer to standard protocols in the communication field. For example, it can include LTE protocols, NR protocols, and related protocols applied to future communication systems. The present application does not limit this.

[0171] In the embodiments of the present application, the term "and / or" merely describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, in this document, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0172] In the embodiments of the present application, the term "comprising" can refer to direct inclusion or indirect inclusion. Optionally, the "comprising" mentioned in the embodiments of the present application can be replaced with "indicating" or "used to determine". For example, A comprises B can be replaced with A indicates B, or A is used to determine B.

[0173] In various embodiments of the present application, the magnitudes of the sequence numbers of the above processes do not imply the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not impose any limitation on the implementation process of the embodiments of the present application.

[0174] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces. The indirect coupling or communication connection of the devices or units can be in an electrical, mechanical, or other form.

[0175] The unit described as a separated component may or may not be physically separated. The component displayed as a unit may or may not be a physical unit, that is, it can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0176] In addition, in each embodiment of the present application, the functional units can be integrated in one processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0177] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from a website, computer, server, or data center to another website, computer, server, or data center by wire (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be read by a computer or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a digital video disc (DVD)), or a semiconductor medium (such as a solid state disk (SSD)), etc.

[0178] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A wireless communication method, characterized in that, The method includes: The terminal device receives the first information and / or the second information; After the terminal device successfully accesses the first cell, when the terminal device determines that a layer 2 reset needs to be performed, the terminal device performs the layer 2 reset; Wherein, the first cell is the target cell for layer-based handover, the first information is used to indicate whether the terminal device needs to perform the layer 2 reset when switching to the first cell, the second information includes information of multiple cells, the multiple cells include the first cell, the multiple cells are the cells that the terminal device can attempt to perform layer-based handover, and the second information is carried in the handover configuration message; The terminal device preferentially attempts to access the cell indicated in the handover command. When the access to the cell indicated in the handover command fails, the terminal device attempts to access the cell that was indicated in the handover configuration message but not included in the handover command.

2. The method according to claim 1, wherein: The first information is indicated by the conditional handover condition of the first cell; and / or, The first information is indicated by the order of the first cell among multiple cells, where the multiple cells are the cells that the terminal device can attempt to perform layer-based handover.

3. The method according to claim 1, characterized in that The cell that the terminal device preferentially attempts to hand over to is the cell with a higher priority among the multiple cells.

4. The method according to claim 3, wherein The priority associated with the first cell is determined according to one or more of the following information: Whether a layer 2 reset needs to be performed when switching to the first cell; The signal strength of the first cell; The order of the first cell among the multiple cells included in the second information.

5. The method according to any one of claims 1 to 4, characterized in that The method further includes: The terminal device sends the third information; Wherein, the third information is used to indicate that the terminal device has not performed the layer 2 reset before attempting to access the first cell; or, the third information is used to indicate that the terminal device has not performed the layer 2 reset before successfully accessing the first cell.

6. The method according to claim 5, characterized in that The third information is carried in one or more of the following: Medium Access Control layer Control Element (MAC CE), Radio Resource Control (RRC) message, Message 3, Radio Link Control (RLC) status report.

7. A wireless communication method, characterized in that, The method includes: The network device sends the first information and / or the second information to the terminal device; Wherein, the first information is used to indicate whether the terminal device needs to perform a layer 2 reset when the terminal device switches to the first cell. When the terminal device needs to perform the layer 2 reset, the layer 2 reset is performed after the terminal device successfully accesses the first cell. The second information includes information of multiple cells, the multiple cells include the first cell, the multiple cells are the cells that the terminal device can attempt to perform layer-based handover, the second information is carried in the handover configuration message, the terminal device preferentially attempts to access the cell indicated in the handover command. When the access to the cell indicated in the handover command fails, the terminal device attempts to access the cell that was indicated in the handover configuration message but not included in the handover command.

8. The method according to claim 7, wherein: The first information is indicated by the conditional handover condition of the first cell; and / or, The first information is indicated by the order of the first cell among multiple cells, where the multiple cells are cells that the terminal device can attempt to perform a layer-2 handover to.

9. The method according to claim 7, wherein The cell that the terminal device preferentially attempts to hand over to is the cell with a higher priority among the multiple cells.

10. The method according to claim 9, wherein The priority associated with the first cell is determined according to one or more of the following information: Whether a layer-2 reset needs to be performed when handing over to the first cell; The signal strength of the first cell; The order of the first cell among the multiple cells included in the second information.

11. The method according to any one of claims 7-10, characterized in that, The method further includes: The network device receives third information; Wherein, the third information is used to indicate that the terminal device has not performed the layer-2 reset before attempting to access the first cell; or, the third information is used to indicate that the terminal device has not performed the layer-2 reset before successfully accessing the first cell.

12. The method according to claim 11, wherein The third information is carried in one or more of the following: Media Access Control layer Control Element (MAC CE), Radio Resource Control (RRC) message, Message 3, Radio Link Control (RLC) status report.

13. A terminal device, characterized in that, The terminal device includes: Receiving the first information and / or the second information; An execution unit, configured to perform a layer-2 reset when the terminal device determines that a layer-2 reset is required after successfully accessing the first cell; Wherein, the first cell is the target cell of the layer-2 handover, the first information is used to indicate whether the terminal device needs to perform the layer-2 reset when handing over to the first cell, the second information includes information of multiple cells, the multiple cells include the first cell, the multiple cells are cells that the terminal device can attempt to perform a layer-2 handover to, and the second information is carried in a handover configuration message; The terminal device preferentially attempts to access the cell indicated in the handover command. In the case of failure to access the cell indicated in the handover command, the terminal device attempts to access the cell that was indicated in the handover configuration message but not included in the handover command.

14. The terminal device according to claim 13, wherein The first information is indicated by the conditional handover condition of the first cell; and / or, The first information is indicated by the order of the first cell among multiple cells, where the multiple cells are cells that the terminal device can attempt to perform a layer-2 handover to.

15. The terminal device according to claim 13, characterized in that, The cell that the terminal device preferentially attempts to hand over to is the cell with a higher priority among the multiple cells.

16. The terminal device according to claim 15, wherein The priority associated with the first cell is determined according to one or more of the following information: Whether a layer-2 reset needs to be performed when handing over to the first cell; The signal strength of the first cell; The order of the first cell among the multiple cells included in the second information.

17. The terminal device according to any one of claims 13-16, characterized in that, The terminal device is further configured to: Send third information; Wherein, the third information is used to indicate that the terminal device has not performed the layer-2 reset before attempting to access the first cell; or, the third information is used to indicate that the terminal device has not performed the layer-2 reset before successfully accessing the first cell.

18. The terminal device according to claim 17, wherein The third information is carried in one or more of the following: Media Access Control layer control element (MAC CE), Radio Resource Control (RRC) message, Message 3, Radio Link Control (RLC) status report.

19. A network device, characterized in that, The network device includes: a sending unit, configured to send the first information and / or the second information to the terminal device; wherein, the first information is used to indicate whether the terminal device needs to perform a layer 2 reset when the terminal device switches to the first cell, and when the terminal device needs to perform the layer 2 reset, the layer 2 reset is performed after the terminal device successfully accesses the first cell; the second information includes information of multiple cells, the multiple cells include the first cell, the multiple cells are cells to which the terminal device can attempt to perform a lower layer handover, the second information is carried in a handover configuration message, the terminal device preferentially attempts to access the cell indicated in the handover command, and when accessing the cell indicated in the handover command fails, the terminal device attempts to access the cell that is indicated in the handover configuration message but not included in the handover command.

20. The network device according to claim 19, wherein the first information is indicated by the conditional handover condition of the first cell; and / or the first information is indicated by the order of the first cell among multiple cells, where the multiple cells are cells to which the terminal device can attempt to perform a lower layer handover.

21. The network device according to claim 19, characterized in that, The cell to which the terminal device preferentially attempts to hand over is the cell with a higher priority among the multiple cells.

22. The network device according to claim 21, characterized in that, The priority associated with the first cell is determined according to one or more of the following information: whether a layer 2 reset needs to be performed when switching to the first cell; the signal strength of the first cell; the order of the first cell among the multiple cells included in the second information.

23. The network device according to any one of claims 19-22, characterized in that, The network device is further configured to: receive third information; wherein, the third information is used to indicate that the terminal device has not performed the layer 2 reset before attempting to access the first cell; or, the third information is used to indicate that the terminal device has not performed the layer 2 reset before successfully accessing the first cell.

24. The network device according to claim 23, characterized in that, The third information is carried in one or more of the following: Media Access Control layer control element (MAC CE), Radio Resource Control (RRC) message, Message 3, Radio Link Control (RLC) status report.

25. A terminal device, characterized in that, comprising a memory and a processor, the memory is configured to store a program, and the processor is configured to call the program in the memory to enable the terminal device to execute the method according to any one of claims 1-6.

26. A network device, characterized in that, comprising a memory and a processor, the memory is configured to store a program, and the processor is configured to call the program in the memory to enable the network device to execute the method according to any one of claims 7-12.

27. A communication device, characterized in that, comprising a processor, configured to call a program from a memory to enable the device to execute the method according to any one of claims 1-12.

28. A chip, characterized in that, comprising a processor, configured to call a program from a memory, such that the device installed with the chip executes the method according to any one of claims 1-12.

29. A computer-readable storage medium, characterized in that, A program is stored thereon, and the program causes a computer to execute the method according to any one of claims 1-12.

30. A computer program product, characterized in that, It includes a program, and the program causes a computer to execute the method according to any one of claims 1-12.

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