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 comprises: a terminal device executes a Layer 2 reset upon successfully accessing a first cell, wherein the first cell is a target cell of Layer 1 / Layer 2-triggered mobility. Therefore, when the terminal device fails in accessing the first cell, the terminal device may not execute a Layer 2 reset. In this way, even if the access to the first cell fails, the terminal device, upon successfully accessing a second cell which does not require execution of a Layer 2 set, may not execute a Layer 2 reset. Thus, unnecessary Layer 2 resets are avoided, and data packet retransmissions caused by handover are reduced, improving user experience during handover.

Description

Wireless communication method, terminal device, and network device Technical Field

[0001] The present application relates to the field of communication technology, and more specifically, to a wireless communication method, terminal equipment, and network equipment. Background Art

[0002] In related technologies, the switching 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 the switching. Among them, the layer 2 reset may include clearing the radio link control (RLC) cache. With the development of technology, some communication systems have realized the separation of the central unit (CU) and the distributed unit (DU). A CU can manage multiple DUs. Therefore, the cell switching process may have a situation where the DU is not replaced before and after the switching. If the DU is not replaced before and after the switching, the layer 2 reset may not be performed. Based on this, in order to reduce the delay caused by the switching process, some communication systems have introduced the bottom layer switching process (also called layer 1 (L1) / L2 switching) to achieve fast switching.

[0003] Summary of the Invention

[0004] The present application provides a wireless communication method, a terminal device, and a network device. The following introduces various aspects of the present application.

[0005] In a first aspect, a wireless communication method is provided, comprising: after a terminal device successfully accesses a first cell, the terminal device performs a layer 2 reset; wherein the first cell is a target cell for a bottom layer handover.

[0006] In a second aspect, a wireless communication method is provided. The method includes: a network device sending 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 the terminal device successfully accesses the first cell.

[0007] According to a third aspect, a terminal device is provided, characterized in that the terminal device includes: an execution unit for executing a layer 2 reset after the terminal device successfully accesses a first cell; wherein the first cell is a target cell for bottom layer switching.

[0008] 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 if 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.

[0009] In a fifth aspect, a terminal device is provided, comprising a processor and a memory, wherein the memory is used to store one or more computer programs, and the processor is used to call the computer program in the memory so that the terminal device executes part or all of the steps in the method of the first aspect.

[0010] In a sixth aspect, a network device is provided, comprising a processor, a memory, and a transceiver, wherein the memory is used to store one or more computer programs, and the processor is used to call the computer program in the memory so that the network device executes part or all of the steps in the method of the second aspect.

[0011] 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 also include other devices that interact with the terminal device or network device in the solution provided in the embodiment of the present application.

[0012] 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 enables a terminal device and / or a network device to execute part or all of the steps in the methods of the above aspects.

[0013] In a ninth aspect, embodiments of the present application provide a computer program product, wherein the computer program product includes a non-transitory computer-readable storage medium storing a computer program, wherein the computer program is operable to cause a terminal device and / or a network device to perform some or all of the steps of the methods described in each of the above aspects. In some implementations, the computer program product may be a software installation package.

[0014] In the tenth aspect, an embodiment of the present application provides a chip, which includes a memory and a processor. 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 aspects.

[0015] The technical solution provided by the present application can avoid unnecessary layer 2 resets, as specifically analyzed 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 when the access to another second cell that does not require a layer 2 reset is successful, the previously performed layer 2 reset is unnecessary. This is because the second cell does not need to perform a layer 2 reset, that is, the terminal device and the second cell can use the data in the previous RLC cache to continue transmission. However, since the RLC cache 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 the present application, the terminal device will only perform a layer 2 reset after the terminal device successfully accesses the first cell. In other words, the terminal device will not perform a layer 2 reset if access to the first cell fails. Therefore, even if the terminal device fails to access the first cell and successfully accesses the second cell, the terminal device may not perform a layer 2 reset based on the situation of the second cell, thereby avoiding unnecessary layer 2 resets, reducing data packet retransmissions caused by switching, and thereby improving the experience of switching users. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a schematic diagram of a wireless communication system used in an embodiment of the present application.

[0017] FIG2 is an example diagram of a protocol stack entity corresponding to four data bearers.

[0018] FIG3 is an exemplary diagram of a bottom layer switching process.

[0019] FIG4 is a schematic flowchart of a wireless communication method provided in an embodiment of the present application.

[0020] FIG5 is a schematic flowchart of another wireless communication method provided in an embodiment of the present application.

[0021] FIG6 is a schematic structural diagram of a terminal device provided in an embodiment of the present application.

[0022] FIG7 is a schematic structural diagram of a network device provided in an embodiment of the present application.

[0023] FIG8 is a schematic structural diagram of a device for communication provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] The technical solution in this application will be described below with reference to the accompanying drawings.

[0025] Communication System

[0026] FIG1 illustrates a wireless communication system 100 used in an embodiment of the present application. 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.

[0027] FIG1 exemplarily shows a network device and two terminals. Optionally, the wireless communication system 100 may include multiple network devices and each network device may include other numbers of terminal devices within its coverage area, which is not limited in the embodiments of the present application.

[0028] Optionally, the wireless communication system 100 may further include other network entities such as a network controller and a mobility management entity, which is not limited in the embodiment of the present application.

[0029] It should be understood that the technical solutions of the embodiments of the present application can be applied to various communication systems, such as: 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 in this application can also be applied to future communication systems, such as the sixth generation mobile communication system, satellite communication system, etc.

[0030] 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, 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 refer to a device that provides voice and / or data connectivity to a user and can be used to connect people, objects and machines, such as a handheld device with wireless connection function, a vehicle-mounted device, etc. The terminal device in the embodiments of the present application can be a mobile phone, a tablet computer, a laptop computer, a PDA, a mobile internet device (MID), a wearable device, a virtual reality (VR) device, an augmented reality (AR) device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical surgery, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, etc. Optionally, the UE can be used to act 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). For example, a cellular phone and a car communicate with each other using sidelink signals. The cellular phone and smart home devices communicate without relaying the communication signal through a base station.

[0031] The network device in the embodiments of the present application may be a device for communicating with a terminal device. The network device may also include an access network device. The access network device may provide communication coverage for a specific geographical area and may communicate with the terminal device 120 located within the coverage area. The access network device may also be referred to as a radio access network device or a base station. The access network device in the embodiments of the present application may refer to a radio access network (RAN) node (or device) that connects the terminal device to a wireless network. Access network equipment can broadly cover various names as follows, or replace the following names, such as: NodeB, evolved NodeB (eNB), next generation NodeB (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, baseband 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, a micro base station, a relay node, a donor node, or the like, or a combination thereof. A base station may also refer to a communication module, modem, or chip used to be set in the aforementioned device or apparatus. A base station may also be a mobile switching center and a device that performs base station functions in D2D, V2X, and machine-to-machine (M2M) communications, a network-side device in a 6G network, or a device that performs base station functions in future communication systems. A base station may support networks with the same or different access technologies. The embodiments of this application do not limit the specific technology and specific device form used by the access network device.

[0032] Base stations can be fixed or mobile. For example, a helicopter or drone can be configured to act as a mobile base station, and one or more cells can move based on the location of the mobile base station. In other examples, a helicopter or drone can be configured to act as a device that communicates with another base station.

[0033] The communication equipment involved in a wireless communication system can include not only access network equipment and terminal equipment, but also core network elements. Core network elements can be implemented by devices, that is, core network elements are core network devices. It is understood that core network devices can also be a type of network equipment.

[0034] The core network elements in the embodiments of the present application may include network elements that process and forward user signaling and data. For example, the core network equipment may include core network access and mobility management function (AMF), session management function (SMF), user plane gateway, location management function (LMF) and other core network equipment. Among them, the user plane gateway may be a server with functions such as mobility management, routing, and forwarding of user plane data, generally located on the network side, such as a serving gateway (SGW) or a packet data network gateway (PGW) or a user plane network element function entity (UPF). Of course, the core network may also include other network elements, which are not listed here one by one.

[0035] In some deployments, the network device in the embodiments of the present application may refer to a CU or a DU, or the network device may include a CU and a DU. The gNB may also include an AAU.

[0036] The network equipment and terminal devices can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; they can also be deployed in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the scenarios in which the network equipment and terminal devices are located.

[0037] It should be understood that all or part of the functions of the communication device in this application can also be implemented through software functions running on hardware, or through virtualization functions instantiated on a platform (such as a cloud platform).

[0038] CU and DU separation architecture

[0039] Some wireless communication networks (such as 5G communication networks) have implemented the separation of CU and DU. A CU can manage multiple DUs. For example, a CU can manage hundreds or thousands of DUs.

[0040] From the perspective of the communication protocol stack, the control plane entities are located in the CU, while the user plane entities are located in the CU and DU. Specifically, for the user plane entities, the CU includes the Service Data Adaptation Protocol (SDAP) and Packet Data Convergence Protocol (PDCP), while the DU includes the RLC, Medium Access Control (MAC), and Physical Layer (PHY). Figure 2 shows an example of the protocol stack entities corresponding to four data bearers. The different padding indicates the protocol stack entities corresponding to the four data bearers.

[0041] For the CU and DU separation architecture, the cell switching process of the terminal device can be divided into the following three cases (cases 1 to 3).

[0042] Case 1: Switching without replacing the DU.

[0043] For scenario 1, the DU serving the terminal device remains unchanged before and after the handover, and neither does the CU. For handovers that do not change the DU, the RLC entities before and after the handover are in the same DU. Referring to Figure 2, the RLC entities corresponding to data bearer 1 and data bearer 2 are both in the same DU. Therefore, for scenario 1, the terminal device does not need to perform an RLC reset (also known as a Layer 2 reset) after the handover.

[0044] Case 2: Switching without replacing the CU.

[0045] For case 2, before and after the switch, the DU serving the terminal device changes, but the CU does not change. For the switch without changing the CU, the RLC entities before and after the switch 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 switch. Since the CU has not changed, the PDCP does not need to be reset. It can be seen that the switch without changing the CU is essentially similar to the intra-site switch in some communication systems (such as the intra-eNB switch in LTE).

[0046] Case 3: Switching after replacing the CU.

[0047] For case three, before and after the handover, the DU serving the terminal device changes, and the CU also changes. For the handover with a CU change, the RLC entities before and after the handover are not in the same DU, so the RLC needs to be reset. In addition, since the PDCP before and after the handover are not in the same CU, the PDCP needs to be re-established in the target CU through interaction between CUs. It can be seen that the handover with a CU change is essentially similar to the inter-station handover in some communication systems (such as the inter-eNB handover in LTE).

[0048] In related technologies, the handover process requires a Layer 2 reset or RLC reset, with PDCP serving as the anchor point to ensure continuous service data transmission before and after the handover. However, based on the above analysis, if the DU is not replaced before and after the handover, an RLC reset is not actually necessary. Therefore, to reduce the latency caused by the handover process, some communication systems have introduced a lower-layer handover process to achieve fast handover. Below, we will explain lower-layer handover with reference to Figure 3.

[0049] Bottom layer switching

[0050] The bottom layer switching may also be referred to as layer 1 (L1) / layer 2 (L2) switching.

[0051] Figure 3 is a schematic flow chart of a bottom layer handover. In Figure 3, the source cell prepares three candidate target cells for the terminal device: target cell 1, target cell 2, and target cell 3.

[0052] The bottom layer switching process shown in FIG3 includes steps S310 to S340 .

[0053] In step S310, the source cell and each candidate target cell prepare for handover.

[0054] Step S310 may include steps S311 to S316.

[0055] Step S311 : The source cell sends a handover preparation message to the target cell 1 .

[0056] Step S312: The target cell 1 feeds back a handover preparation completion message to the source cell.

[0057] Step S313: The source cell sends a handover preparation message to the target cell 2.

[0058] Step S314: The target cell 2 feeds back a handover preparation completion message to the source cell.

[0059] Step S315 : The source cell sends a handover preparation message to the target cell 3 .

[0060] Step S316: The target cell 3 feeds back a handover preparation completion message to the source cell.

[0061] In step S320, the source cell sends a handover configuration message to the terminal device. The handover configuration message is transmitted via radio resource control (RRC) signaling.

[0062] The handover configuration message may include configuration information of all candidate target cells (target cell 1 to target cell 3).

[0063] Step S330 : The terminal device performs timing advance (TA) pre-acquisition and measurement.

[0064] The terminal device may send a preamble to each candidate target cell to obtain a TA. The TA may be notified to the terminal device by each target cell; or, alternatively, each target cell may not notify the terminal device of the TA, and the TA may be stored by the source cell.

[0065] The terminal device can also measure each candidate target cell to obtain measurement results.

[0066] Step S340: The terminal device reports the measurement results of each candidate target cell to the source cell.

[0067] The source cell may determine the target cell to which the terminal device needs to be handed over based on the measurement result, and inform the terminal device via underlying signaling. For example, the method shown in FIG3 may include steps S350, S360, or S370.

[0068] If the source cell determines that the terminal device is switched to the target cell 1, the method shown in FIG3 may include step S350.

[0069] Step S350 may include steps S351 to S353.

[0070] In step S351, the source cell sends a handover command to the terminal device via L1 / L2 signaling. The handover command is used to indicate that the terminal device needs to be handed over to the target cell 1.

[0071] In step S352, the terminal device sends uplink data to the target cell 1 and receives a confirmation message sent by the target cell 1. At this point, the handover process ends.

[0072] Among them, if the terminal device has pre-acquired the TA of target cell 1 and the network device corresponding to target cell 1 has allocated a configured grant (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 1, or the network device corresponding to target cell 1 has not allocated a CG to the terminal device, the terminal device obtains uplink resources and TA through a random access process and sends uplink data.

[0073] If the source cell determines that the terminal device is switched to the target cell 2, the method shown in FIG3 may include step S360.

[0074] Step S360 may include steps S361 to S363.

[0075] In step S361, the source cell sends a handover command to the terminal device via L1 / L2 signaling. The handover command is used to indicate that the terminal device needs to be handed over to the target cell 2.

[0076] In step S362, the terminal device sends uplink data to the target cell 2 and receives a confirmation message sent by the target cell 2. At this point, the handover process ends.

[0077] Among them, if the terminal device has pre-acquired the TA of target cell 2 and the network device corresponding to target cell 2 has allocated 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 2, or the network device corresponding to target cell 2 has not allocated a CG to the terminal device, the terminal device obtains uplink resources and TA through a random access process and sends uplink data.

[0078] If the source cell determines that the terminal device is switched to the target cell 3, the method shown in FIG3 may include step S370.

[0079] Step S370 may include steps S371 to S373.

[0080] In step S371, the source cell sends a handover command to the terminal device via L1 / L2 signaling. The handover command is used to indicate that the terminal device needs to be handed over to the target cell 3.

[0081] In step S372, the terminal device sends uplink data to the target cell 3 and receives a confirmation message sent by the target cell 3. At this point, the handover process ends.

[0082] Among them, if the terminal device has pre-acquired the TA of the target cell 3 and the network device corresponding to the target cell 3 has allocated 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 the target cell 3, or the network device corresponding to the target cell 3 has not allocated a CG to the terminal device, the terminal device obtains uplink resources and TA through a random access process and sends uplink data.

[0083] In the method shown in Figure 3, if the terminal device switches to target cell 1, it is a handover without replacing the DU; if the terminal device switches to target cell 2, it is a handover with replacing the DU; if the terminal device switches to target cell 3, it is a handover with replacing the CU. Therefore, if the terminal device switches to target cell 1, the terminal device does not need to perform an L2 reset; if the terminal device switches to target cell 2 or target cell 3, an L2 reset is required.

[0084] Figure 3 illustrates the underlying handover process, where the source cell determines which candidate target cell the terminal device switches to. Similarly, underlying handover can also be applied to a conditional handover process. Similar to the process shown in Figure 3, in a conditional handover process, the terminal device can pre-acquire the configuration information of one or more potential target cells and select a target cell to switch to based on measurement results.

[0085] It should be noted that in the conditional switching process, if multiple quasi-target cells are pre-configured, when the terminal device selects target cell 2 for access but fails to access, the terminal device can select another quasi-target cell (such as target cell 3) for access. In this case, when switching to target cell 2 or target cell 3, the terminal device needs to perform an L2 reset.

[0086] This application optimizes the underlying switching process. Figure 4 is a schematic structural diagram of a wireless communication method provided by an embodiment of the present application.

[0087] The method shown in Figure 4 can be executed by a terminal device. The method shown in Figure 4 includes step S410.

[0088] Step S410: After the terminal device successfully accesses the first cell, the terminal device performs a layer 2 reset.

[0089] The first cell may be the target cell for the underlying handover. For example, the first cell may be the target cell indicated by a handover command sent by the network device. In other words, the first cell may be the target cell determined by the network device. Alternatively, the first cell may be the target cell selected by the terminal device during the conditional handover process. In other words, the first cell may be the target cell determined by the terminal device itself.

[0090] As described above, a Layer 2 reset performed by a terminal device can be understood as an RLC reset. An RLC reset can refer to clearing the RLC buffer. For example, a Layer 2 reset can include: clearing the sender's RLC buffer; and / or clearing the receiver's RLC buffer.

[0091] As can be seen from step S410, the terminal device will perform layer 2 reset only after the terminal device successfully accesses the first cell. In other words, if the terminal device fails to access the first cell, the terminal device may not perform layer 2 reset.

[0092] This technical solution can avoid unnecessary layer 2 resets, as specifically analyzed below. 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 when accessing another second cell that does not require a layer 2 reset is successful, the previously performed layer 2 reset is unnecessary. This is because the second cell does not need to perform a layer 2 reset, that is, the terminal device and the second cell can continue to interact using the data in the previous RLC cache. However, since the RLC cache has been cleared before attempting to access the first cell, it is difficult for the terminal device to continue to transmit data between the RLC of the second cell or data needs to be transmitted repeatedly. For example, for uplink transmission, the RLC status report sent by the second cell may indicate that the second cell requires retransmission of some RLC service data units (SDUs). If the RLC cache is not cleared, the terminal device can find these RLC SDUs from the RLC cache and retransmit them to the second cell. However, when the RLC cache is cleared, the terminal device cannot find these RLC SDUs from the RLC cache and cannot transmit these RLC SDUs. For another example, for downlink transmission, if Layer 2 reset is not performed, the terminal device can send an RLC status report to the second cell and request retransmission of some RLC SDU or RLS SDU segments, thereby avoiding excessive retransmission of data. However, in the case of performing a Layer 2 reset, it is impossible to avoid excessive retransmission of data based on this technical solution. Based on the present application, the terminal device will perform a Layer 2 reset only after the terminal device successfully accesses the first cell. In other words, in the case of a failure 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 may not perform a Layer 2 reset according to the situation of the second cell, thereby avoiding unnecessary Layer 2 resets, reducing the retransmission of data packets caused by switching, and thereby improving the experience of the switching user.

[0093] In some embodiments, if the terminal device determines that a Layer 2 reset is required, the terminal device may execute step S410. For example, the terminal device may determine whether a Layer 2 reset is required when switching to the first cell. If a Layer 2 reset is not required, the terminal device does not execute the Layer 2 reset; if a Layer 2 reset is required, the terminal device executes the Layer 2 reset (i.e., executes step S410). The terminal device may determine whether a Layer 2 reset is required based on the first information in step S405 described below.

[0094] It should be noted that whether a layer 2 reset needs to be performed can be at the cell level. That is, for different cells, whether the terminal device needs to perform a layer 2 reset may be different. For example, in the case where the switch to the first cell is a switch that does not replace the DU, the terminal device does not need to perform a layer 2 reset. Alternatively, in the case where the switch to the first cell is a switch that replaces the DU but does not replace the CU, the terminal device needs to perform a layer 2 reset. Alternatively, in the case where the switch to the first cell is a switch that replaces the CU, the terminal device needs to perform a layer 2 reset.

[0095] It should be noted that whether to replace the DU may be one of the conditions for whether to perform a Layer 2 reset (or not). The conditions for whether to perform a Layer 2 reset may also include other conditions. When some or all of the conditions for whether to perform a Layer 2 reset are met, it can be determined that a Layer 2 reset needs to be performed; or, when some or all of the conditions for whether to perform a Layer 2 reset are met, it can be determined that a Layer 2 reset does not need to be performed. For example, in the case where switching to the first cell is to replace the DU, if the two DUs before and after the replacement can share storage space through a large-capacity transmission channel or a cloud connection, the terminal device may not need to perform a Layer 2 reset.

[0096] In some embodiments, the method shown in FIG4 may further include step S405. Step S405 may be performed by a terminal device and a network device. The network device may be a network device corresponding to a source cell of the terminal device.

[0097] Step S405: The network device sends first information to the terminal device.

[0098] The first information may be used to indicate whether the terminal device needs to perform a layer 2 reset when switching to the first cell.

[0099] Based on the first information, the terminal device can determine whether it is necessary to perform a layer 2 reset when switching to the first cell, thereby determining whether it is necessary to perform a layer 2 reset after successfully accessing the first cell.

[0100] In some embodiments, the first information may be indicated in an explicit manner.

[0101] Exemplarily, the first information may include a first bit, a first Boolean value, or a first enumeration value corresponding to the first cell. For example, when the first bit is 0, it may indicate that Layer 2 reset does not need to be performed when switching to the first cell; when the first bit is 1, it may indicate that Layer 2 reset needs to be performed when switching to the first cell. Alternatively, when the first bit is 1, it may indicate that Layer 2 reset does not need to be performed when switching to the first cell; when the first bit is 0, it may indicate that Layer 2 reset needs to be performed when switching to the first cell. For another example, when the first Boolean value is "true", it may indicate that Layer 2 reset does not need to be performed when switching to the first cell; when the first Boolean value is "false", it may indicate that Layer 2 reset needs to be performed when switching to the first cell. Alternatively, when the first Boolean value is "false", it may indicate that Layer 2 reset does not need to be performed when switching to the first cell; when the first Boolean value is "true", it may indicate that Layer 2 reset needs to be performed when switching to the first cell. For another example, the first enumeration value may indicate "L2 reset needs to be performed" or "L2 reset does not need to be performed".

[0102] For example, for conditional handover, the network device may divide quasi-target cells into a first group and a second group. The first group may include one or more cells that require L2 reset; the second group may include one or more cells that do not require L2 reset. One or more cells may be quasi-target cells of the terminal device.

[0103] In some embodiments, the first information may be indicated in an implicit manner.

[0104] Exemplarily, the first information may be indicated by a conditional switching condition of the first cell. The terminal device may determine whether to perform an L2 reset for the first cell according to the conditional switching condition configured by the network device for the first cell.

[0105] Optionally, if an L2 reset is required for the first cell, the network device may set the conditional switching condition for the first cell to a first condition that is relatively difficult to meet; if an L2 reset is not required for the first cell, the network device may set the conditional switching condition for the first cell to a second condition that is relatively easy to meet. Optionally, the first condition may include: the RSRP of the first cell reaches a first value, and the first cell meets the conditional switching condition; the second condition may include: the RSRP of the first cell reaches a second value, and the first cell meets the conditional switching condition; wherein the first value is greater than the second value.

[0106] Optionally, the network device may configure multiple handover conditions for all quasi-target cells; or, for quasi-target cells with a frequency band in frequency range (FR) 1, multiple handover conditions; or, for quasi-target cells with a frequency band in FR2, multiple handover conditions. 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.

[0107] Exemplarily, the first information may indicate whether the terminal device needs to perform a Layer 2 reset by the order of the first cell in the plurality of cells. The plurality of cells may be cells in which the terminal device can attempt to perform a layer 2 handover. For example, the plurality of cells may be represented by a cell list. For the cells in the cell list, the first half may be cells that do not require an L2 reset, and the second half may be cells that require an L2 reset. Alternatively, for the cells in the cell list, the first half may be cells that require an L2 reset, and the second half may be cells that do not require an L2 reset.

[0108] In some embodiments, the network device may send second information to the terminal device. The second information may include information of multiple cells. The multiple cells may be cells in which the terminal device can attempt to perform a bottom layer handover.

[0109] As can be seen from the above, in the underlying switching process, the network device or the terminal device can determine the target cell for switching based on the L1 / L2 measurement results of the terminal device. Since the L1 / L2 measurement results have not been smoothed and filtered, the fluctuations are large. The probability of switching failure based on the L1 / L2 measurement results is relatively high. If the network device only indicates to the terminal device a cell that can attempt to perform underlying switching (for example, the technical solution in the related technology that only includes one cell in the switching command), then after the cell switching fails, the terminal device can only reselect the cell and initiate a wireless link establishment. This will result in a lower switching success rate and a longer data transmission interruption time. Based on the present application, the terminal device can try to switch to multiple cells indicated by the second information in turn, thereby improving the switching success rate and reducing the data transmission interruption time.

[0110] In some embodiments, the second information may be carried in a handover command. That is, the handover command may include multiple cells. The multiple cells may all be cells in which the terminal device can perform L1 / L2 handover. The multiple cells indicated by the handover command may all be cells that meet the handover conditions. In other words, the L / L2 measurement results of the multiple cells indicated by the handover command all meet the handover requirements.

[0111] In some embodiments, the second information can be carried in a handover configuration message. In other words, the terminal device can select a cell indicated in the handover configuration message to initiate random access. Since the alternative target cell indicated in the handover configuration message is a cell that has interacted with the source cell, the terminal device accesses the alternative target cell indicated in the handover configuration message, and can also be processed according to the handover process. Continue to refer to the scenario shown in Figure 3. 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 switch. This is because, in step S310, the handover preparation process is performed between the source cell and the target cell 1, target cell 2 and target cell 3.

[0112] In some embodiments, the second information may be carried in a handover indication, which may be L1 / L2 signaling, and which may be used to indicate one or more target cells.

[0113] It should be noted that the second information may be carried in the handover command alone, or may be carried in at least two of the handover command, the handover configuration message, and the handover indication.

[0114] In the case where the second information is carried separately in the handover command, the handover command may indicate multiple cells. If the terminal device fails in attempting to access the multiple cells indicated by the handover command, the terminal device may perform cell reselection and perform RRC re-establishment.

[0115] In the case where the second information is carried in the handover command and the handover configuration message, the handover command may indicate one or more cells, and the handover configuration message may indicate one or more cells. All cells indicated in the handover command and the handover configuration message may constitute multiple cells indicated by the second information. For example, the handover command may include only one cell. The terminal device may preferentially attempt to access the cell indicated in the handover command. In the case where access to the cell indicated in the handover command fails, the terminal device may select a cell indicated in the handover configuration message but not included in the handover command, and initiate random access to the selected cell. Alternatively, the handover command may include multiple cells. The terminal device may preferentially attempt to access the multiple cells indicated by the handover command. In the case where access to the multiple cells indicated in the handover command fails, the terminal device may select a cell indicated in the handover configuration message but not included in the handover command, and initiate random access to the selected cell.

[0116] The following description will be made using Figure 5 as an example. The method shown in Figure 5 includes step S510 and step S520.

[0117] Step S510: The network device sends a switching configuration message to the terminal device.

[0118] The handover configuration message indicates five cells: Cell A, Cell B, Cell C, Cell D, and Cell E.

[0119] Step S520: The network device sends a switching command to the terminal device.

[0120] The handover command indicates three cells: cell B, cell C, and cell E.

[0121] For the scenario shown in Figure 5, if the terminal device fails to access cell B, cell C, and cell E, the terminal device can perform cell reselection and RRC re-establishment. Alternatively, if 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.

[0122] Optionally, in step S520, the handover command may indicate only one cell. For example, the cell indicated by the handover command may be cell B. If the terminal device fails to access cell B, the terminal device may attempt to access cell A, cell C, cell D, or cell E.

[0123] It should be noted that, for the multiple cells indicated by the second information, when the terminal device counts the switching parameters, it can be counted separately or together with the cells in the related technology. The switching parameters may include one or more of the following: number of switching times, switching delay, etc., and statistical information. For example, for the multiple cells indicated by the second information, the statistical information may include one or more of the following: the probability of successfully switching into the first cell among the multiple cells, the number of successful switching into the first cell among the multiple cells, the frequency of successfully switching into the first cell among the multiple cells, the probability of successfully switching into a cell other than the first cell among the multiple cells, the number of successful switching into a cell other than the first cell among the multiple cells, and the frequency of successfully switching into a cell other than the first cell among the multiple cells. For another example, the statistical information may include one or more of the following: the number of successful switches into cells among multiple cells that do not require layer 2 reset, the probability of successfully switching into cells among multiple cells that do not require layer 2 reset, the frequency of successful switches into cells among multiple cells that do not require layer 2 reset, the number of successful switches into cells among multiple cells that require layer 2 reset, the probability of successfully switching into cells among multiple cells that require layer 2 reset, and the frequency of successful switches into cells among multiple cells that require layer 2 reset.

[0124] The terminal device may attempt to access the multiple cells indicated by the second information in sequence according to a certain order. The following describes the access order of the terminal device to access the multiple cells.

[0125] 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, the terminal device may first try to access the first cell in the cell list; if the first cell access fails, the terminal device may try to access the second cell in the cell list; if the second cell access fails, the terminal device may try to access the third cell in the cell list... until trying to access the last cell in the cell list. Continuing to refer to Figure 5, taking the second information only carried in the switching command as an example, the terminal device may try to access in the order of cell B, cell C, and cell E. That is, the terminal device may first try to access cell B; if access to cell B fails, the terminal device may try to access cell C; if access to cell C fails, the terminal device may try to access cell E.

[0126] In some embodiments, the terminal device may preferentially attempt to switch to a cell with a higher priority among the multiple cells indicated by the second information. For example, if 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 access to the first cell fails, the terminal device may then attempt to access the second cell.

[0127] The priority of the first cell association may be determined according to one or more of the following information: whether handover to the first cell requires performing a layer 2 reset, the signal strength of the first cell, and the order of the first cell in the plurality of cells included in the second information.

[0128] For example, the priority of cells that do not require Layer 2 reset can be higher than the priority of cells that do not require Layer 2 reset. In other words, the terminal device can first attempt to access cells that do not require Layer 2 reset, and then attempt to access cells that require Layer 2 reset, based on the principle of "first attempt to access cells that do not require Layer 2 reset." Continuing with Figure 5, if cells B and E are cells that do not require Layer 2 reset, and cell C is a cell that requires Layer 2 reset, the terminal device can attempt to access cells B, E, and C in that order.

[0129] For example, the priority of cells with high signal strength may be higher than that of cells with low signal strength. In other words, the terminal device may try to access cells one by one from cells with high signal strength to cells with low signal strength according to the measured signal strength.

[0130] For another example, among the multiple cells included in the second information, the priority associated with the cell in the earlier order may be higher than the priority associated with the cell in the later order. In other words, the terminal device may attempt to access the cells one at a time according to the order of the multiple cells included in the second information.

[0131] The above embodiments may be implemented individually or in combination. For example, when two cells have the same priority, the terminal device may attempt to access the two cells in the order in which they appear in the cell list.

[0132] 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 did not perform a layer 2 reset before attempting to access the first cell. Alternatively, the third information may be used to indicate that the terminal device did not perform a layer 2 reset before successfully accessing the first cell.

[0133] Exemplarily, the third information may be carried in one or more of the following: an RLC status report, a media access control element (MAC CE), an RRC message, or 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 subheader. When the third information is carried in the RRC message, the third information may be carried in a 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 physical layer puncturing within msg3.

[0134] 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 did not perform a layer 2 reset before attempting to access the first cell, but also inform the network device of the RLC status of the terminal device.

[0135] For example, if the terminal device has obtained the CG resources allocated by the first cell and has obtained the TA, the terminal device can send an RLC status report when attempting to access the first cell. 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 switching 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 look for the next cell to attempt access.

[0136] The method embodiments of the present application are described in detail above, and the device embodiments of the present application are described in detail below. It should be understood that the description of the method embodiments corresponds to the description of the device embodiments, so for parts not described in detail, reference can be made to the above method embodiments.

[0137] FIG6 is a schematic structural diagram of a terminal device 600 provided in an embodiment of the present application. The terminal device 600 includes an execution unit 610 .

[0138] The execution unit 610 is used to perform layer 2 reset after the terminal device successfully accesses the first cell; wherein the first cell is the target cell of the bottom layer switching.

[0139] 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.

[0140] In some embodiments, the terminal device 600 is further used to: receive first information; wherein the first information is used to indicate: when switching to the first cell, whether the terminal device needs to perform a layer 2 reset.

[0141] In some embodiments, the first information is indicated by a conditional switching condition of the first cell; and / or, the first information is indicated by an order of the first cell in a plurality of cells, wherein the plurality of cells are cells in which the terminal device can attempt to perform underlying switching.

[0142] In some embodiments, the terminal device 600 is further used 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 in which the terminal device can attempt to perform underlying switching.

[0143] In some embodiments, the second information is carried in one or more of the following messages: a handover configuration message, a handover command, and a handover indication.

[0144] In some embodiments, the cell to which the terminal device preferentially attempts to switch is a cell with a higher priority among multiple cells.

[0145] In some embodiments, the priority associated with the first cell is determined according to one or more of the following information: whether handover to the first cell requires performing a layer 2 reset; the signal strength of the first cell; and the order of the first cell among the multiple cells included in the second information.

[0146] In some embodiments, the terminal device 600 is further used to: send third information; wherein the third information is used to indicate that the terminal device did not perform a layer 2 reset before attempting to access the first cell.

[0147] In some embodiments, the third information is carried in one or more of the following: MAC CE, RRC message, Message 3, RLC status report.

[0148] In an optional embodiment, the execution unit 610 may be a processor 810. The terminal tanning device 600 may further include a memory 820 and a transceiver 830, as shown in FIG8 .

[0149] FIG7 shows a network device 700 provided in an embodiment of the present application. The network device 700 includes a sending unit 710 .

[0150] The sending unit 710 is used to send first information to the terminal device; wherein the first information is used to indicate: when the terminal device switches to the first cell, whether the terminal device needs to perform a layer 2 reset; when the terminal device needs to perform a layer 2 reset, the layer 2 reset is performed after successfully accessing the first cell.

[0151] In some embodiments, the first information is indicated by a conditional switching condition of the first cell; and / or, the first information is indicated by an order of the first cell in a plurality of cells, wherein the plurality of cells are cells in which the terminal device can attempt to perform underlying switching.

[0152] In some embodiments, the network device 700 is further used 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 in which the terminal device can attempt to perform underlying switching.

[0153] In some embodiments, the second information is carried in one or more of the following messages: a handover configuration message, a handover command, and a handover indication.

[0154] In some embodiments, the cell to which the terminal device preferentially attempts to switch is a cell with a higher priority among multiple cells.

[0155] In some embodiments, the priority associated with the first cell is determined according to one or more of the following information: whether handover to the first cell requires performing a layer 2 reset; the signal strength of the first cell; and the order of the first cell among the multiple cells included in the second information.

[0156] In some embodiments, the network device 700 is further used to: receive third information; wherein the third information is used to indicate that the terminal device did not perform a layer 2 reset before attempting to access the first cell.

[0157] In some embodiments, the third information is carried in one or more of the following: MAC CE, RRC message, Message 3, RLC status report.

[0158] In an optional embodiment, the sending unit 710 may be a transceiver 830. The network device 700 may further include a processor 810 and a memory 820, as specifically shown in FIG8 .

[0159] Figure 8 is a schematic block diagram of a communication device according to an embodiment of the present application. The dashed lines in Figure 8 indicate that the unit or module is optional. The device 800 can be used to implement the method described in the above method embodiment. The device 800 can be a chip, a terminal device, or a network device.

[0160] The device 800 may include one or more processors 810. The processor 810 may support the device 800 to implement the method described in the method embodiment above. The processor 810 may be a general-purpose processor or a special-purpose processor. For example, the processor may be a central processing unit (CPU). Alternatively, the processor may be another general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, etc. The general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0161] The apparatus 800 may further include one or more memories 820. The memories 820 store programs that can be executed by the processor 810, causing the processor 810 to perform the methods described in the above method embodiments. The memories 820 may be independent of the processor 810 or integrated into the processor 810.

[0162] The apparatus 800 may further include a transceiver 830. The processor 810 may communicate with other devices or chips via the transceiver 830. For example, the processor 810 may transmit and receive data with other devices or chips via the transceiver 830.

[0163] The present application also provides a computer-readable storage medium for storing a program. The computer-readable storage medium can be applied to a terminal or network device provided in the present application, and the program enables a computer to execute the method performed by the terminal or network device in each embodiment of the present application.

[0164] The present application also provides a computer program product. The computer program product includes a program. The computer program product can be applied to a terminal or network device provided in the present application, and the program causes a computer to execute the method performed by the terminal or network device in each embodiment of the present application.

[0165] The embodiments of the present application also provide a computer program. The computer program can be applied to the terminal or network device provided in the embodiments of the present application, and the computer program enables a computer to execute the method performed by the terminal or network device in each embodiment of the present application.

[0166] It should be understood that the terms "system" and "network" in this application can be used interchangeably. In addition, the terms used in this application are only used to explain the specific embodiments of this application and are not intended to limit this application. The terms "first", "second", "third", and "fourth" in the specification and claims of this application and the accompanying drawings are used to distinguish different objects rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0167] In the embodiments of this application, the term "indication" may refer to a direct indication, an indirect indication, or an indication of an association. For example, "A indicates B" may refer to a direct indication of B, e.g., B can obtain information through A; it may refer to an indirect indication of B, e.g., A indicates C, e.g., B can obtain information through C; or it may refer to an association between A and B.

[0168] In the embodiment of the present application, "B corresponding to A" means that B is associated with A and B can be determined based on A. However, it should be understood that determining B based on A does not mean determining B based solely on A, but B can also be determined based on A and / or other information.

[0169] In the embodiments of the present application, the term "corresponding" may indicate a direct or indirect correspondence between the two, or an association relationship between the two, or a relationship between indication and indication, configuration and configuration, etc.

[0170] In the embodiments of the present application, "pre-definition" or "pre-configuration" may be implemented by pre-storing corresponding codes, tables, or other methods that can be used to indicate relevant information in a device (e.g., a terminal device and a network device). The present application does not limit the specific implementation method. For example, pre-definition may refer to information defined in a protocol.

[0171] In the embodiments of the present application, the “protocol” may refer to a standard protocol in the communications field, for example, it may include an LTE protocol, an NR protocol, and related protocols used in future communication systems, and the present application does not limit this.

[0172] In the embodiments of this application, the term "and / or" is simply a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0173] In the embodiments of this application, the term "include" can refer to direct inclusion or indirect inclusion. Alternatively, the term "include" in the embodiments of this application can be replaced with "indicates" or "is used to determine." For example, "A includes B" can be replaced with "A indicates B" or "A is used to determine B."

[0174] In various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0175] In the several embodiments provided in this 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 schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as 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 mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0176] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0177] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0178] 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 process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium 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 available media integrated therein. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital versatile disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0179] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A wireless communication method, characterized in that: The method comprises: After the terminal device successfully accesses the first cell, the terminal device performs a layer 2 reset; The first cell is a target cell for bottom layer switching.

2. The method according to claim 1, characterized in that The terminal device performing a layer 2 reset comprises: In the case where the terminal device determines that the layer 2 reset needs to be performed, the terminal device performs the layer 2 reset.

3. The method according to claim 2, characterized in that The method further comprises: The terminal device receives first information; The first information is used to indicate whether the terminal device needs to perform the layer 2 reset when switching to the first cell.

4. The method according to claim 3, characterized in that The first information is indicated by a conditional switching condition of the first cell; and / or, The first information is indicated by an order of the first cell in a plurality of cells, wherein the plurality of cells are cells in which the terminal device can attempt to perform a bottom layer handover.

5. The method according to any one of claims 1 to 4, characterized in that: The method further comprises: The terminal device receives second information; The second information includes information of multiple cells, the multiple cells include the first cell, and the multiple cells are cells in which the terminal device can attempt to perform underlying switching.

6. The method according to claim 5, characterized in that The second information is carried in one or more of the following messages: a switching configuration message, a switching command, and a switching indication.

7. The method according to claim 5 or 6, characterized in that: The cell to which the terminal device preferentially attempts to switch is a cell with a high priority among the multiple cells.

8. The method according to claim 7, characterized in that The priority of the first cell association is determined according to one or more of the following information: Whether switching to the first cell requires performing a layer 2 reset; the signal strength of the first cell; The order of the first cell among the multiple cells included in the second information.

9. The method according to any one of claims 1 to 8, characterized in that The method further comprises: The terminal device sends third information; The third information is used to indicate that the terminal device did not perform the layer 2 reset before attempting to access the first cell; or, the third information is used to indicate that the terminal device did not perform the layer 2 reset before successfully accessing the first cell.

10. The method according to claim 9, characterized in that The third information is carried in one or more of the following: a media access control layer control element MAC CE, a radio resource control RRC message, message 3, and a radio link control RLC status report.

11. A wireless communication method, characterized in that: The method comprises: The network device sends first information to the terminal device; Among them, the first information is used to indicate: when the terminal device switches to the first cell, whether the terminal device needs to perform the layer 2 reset; 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.

12. The method according to claim 11, characterized in that The first information is indicated by a conditional switching condition of the first cell; and / or, The first information is indicated by an order of the first cell in a plurality of cells, wherein the plurality of cells are cells in which the terminal device can attempt to perform a bottom layer handover.

13. The method according to claim 11 or 12, characterized in that: The method further comprises: The network device sends second information to the terminal device; The second information includes information of multiple cells, the multiple cells include the first cell, and the multiple cells are cells in which the terminal device can attempt to perform underlying switching.

14. The method according to claim 13, characterized in that The second information is carried in one or more of the following messages: a switching configuration message, a switching command, and a switching indication.

15. The method according to claim 13 or 14, characterized in that The cell to which the terminal device preferentially attempts to switch is a cell with a high priority among the multiple cells.

16. The method according to claim 15, characterized in that The priority of the first cell association is determined according to one or more of the following information: Whether switching to the first cell requires performing a layer 2 reset; the signal strength of the first cell; The order of the first cell among the multiple cells included in the second information.

17. The method according to any one of claims 11 to 16, characterized in that The method further comprises: The network device receives third information; The third information is used to indicate that the terminal device did not perform the layer 2 reset before attempting to access the first cell; or, the third information is used to indicate that the terminal device did not perform the layer 2 reset before successfully accessing the first cell.

18. The method according to claim 17, characterized in that The third information is carried in one or more of the following: a media access control layer control element MAC CE, a radio resource control RRC message, message 3, and a radio link control RLC status report.

19. A terminal device, characterized in that: The terminal device comprises: An execution unit, configured to execute a layer 2 reset after the terminal device successfully accesses the first cell; The first cell is a target cell for bottom layer switching.

20. The terminal device according to claim 19, characterized in that: The execution unit is used for: In the case where the terminal device determines that the layer 2 reset needs to be performed, the terminal device performs the layer 2 reset.

21. The terminal device according to claim 20, characterized in that: The terminal device is also used for: receiving a first message; The first information is used to indicate whether the terminal device needs to perform the layer 2 reset when switching to the first cell.

22. The terminal device according to claim 21, characterized in that: The first information is indicated by a conditional switching condition of the first cell; and / or, The first information is indicated by an order of the first cell in a plurality of cells, wherein the plurality of cells are cells in which the terminal device can attempt to perform a bottom layer handover.

23. The terminal device according to any one of claims 19 to 22, characterized in that: The terminal device is also used for: receiving second information; The second information includes information of multiple cells, the multiple cells include the first cell, and the multiple cells are cells in which the terminal device can attempt to perform underlying switching.

24. The terminal device according to claim 23, characterized in that: The second information is carried in one or more of the following messages: a switching configuration message, a switching command, and a switching indication.

25. The terminal device according to claim 23 or 24, characterized in that: The cell to which the terminal device preferentially attempts to switch is a cell with a high priority among the multiple cells.

26. The terminal device according to claim 25, characterized in that: The priority of the first cell association is determined according to one or more of the following information: Whether switching to the first cell requires performing a layer 2 reset; the signal strength of the first cell; The order of the first cell among the multiple cells included in the second information.

27. The terminal device according to any one of claims 19 to 26, characterized in that: The terminal device is also used for: Sending a third message; The third information is used to indicate that the terminal device did not perform the layer 2 reset before attempting to access the first cell; or, the third information is used to indicate that the terminal device did not perform the layer 2 reset before successfully accessing the first cell.

28. The terminal device according to claim 27, characterized in that: The third information is carried in one or more of the following: a media access control layer control element MAC CE, a radio resource control RRC message, message 3, and a radio link control RLC status report.

29. A network device, characterized in that: The network equipment includes: A sending unit, configured to send first information to a terminal device; The first information is used to indicate whether the terminal device needs to perform the layer 2 reset when the terminal device switches to the first cell. If 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.

30. The network device according to claim 29, characterized in that: The first information is indicated by a conditional switching condition of the first cell; and / or, The first information is indicated by an order of the first cell in a plurality of cells, wherein the plurality of cells are cells in which the terminal device can attempt to perform a bottom layer handover.

31. The network device according to claim 29 or 30, characterized in that: The network device is also used for: Sending second information to the terminal device; The second information includes information of multiple cells, the multiple cells include the first cell, and the multiple cells are cells in which the terminal device can attempt to perform underlying switching.

32. The network device according to claim 31, characterized in that: The second information is carried in one or more of the following messages: a switching configuration message, a switching command, and a switching indication.

33. The network device according to claim 31 or 32, characterized in that: The cell to which the terminal device preferentially attempts to switch is a cell with a high priority among the multiple cells.

34. The network device according to claim 33, characterized in that: The priority of the first cell association is determined according to one or more of the following information: Whether switching to the first cell requires performing a layer 2 reset; the signal strength of the first cell; The order of the first cell among the multiple cells included in the second information.

35. The network device according to any one of claims 29 to 34, characterized in that: The network device is also used for: receiving third information; The third information is used to indicate that the terminal device did not perform the layer 2 reset before attempting to access the first cell; or, the third information is used to indicate that the terminal device did not perform the layer 2 reset before successfully accessing the first cell.

36. The network device according to claim 35, characterized in that The third information is carried in one or more of the following: a media access control layer control element MAC CE, a radio resource control RRC message, message 3, and a radio link control RLC status report.

37. A terminal device, characterized in that: The method comprises a memory and a processor, wherein the memory is used to store a program, and the processor is used to call the program in the memory so that the terminal device executes the method according to any one of claims 1 to 10.

38. A network device, characterized in that: The device comprises a memory and a processor, wherein the memory is used to store a program, and the processor is used to call the program in the memory so that the network device executes the method according to any one of claims 11 to 18.

39. A device, characterized in that The device comprises a processor, configured to call a program from a memory so as to enable the device to execute the method according to any one of claims 1 to 18.

40. A chip, characterized in that: It comprises a processor, which is used to call a program from a memory, so that a device equipped with the chip executes a method as claimed in any one of claims 1 to 18.

41. A computer-readable storage medium, characterized in that A program is stored thereon, and the program enables a computer to execute the method according to any one of claims 1 to 18.

42. A computer program product, characterized in that The method comprises a program which causes a computer to execute the method according to any one of claims 1 to 18.

43. A computer program, characterized in that The computer program enables a computer to execute the method according to any one of claims 1 to 18.

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