Communication method, communication apparatus and communication system

Abstract

Provided in the embodiments of the present application are a communication method, a communication apparatus and a communication system. The communication apparatus is applied to a terminal device. The apparatus comprises a first processing unit, which controls the terminal device to perform the following operations: receiving indication information sent by a network device; and for an L1 / 2 triggered mobility (LTM) cell switch process, the terminal device executing first processing on the basis of the indication information, wherein the first processing at least comprises packet data convergence protocol (PDCP) data recovery and / or PDCP entity reestablishment.

Description

Communication method, communication device and communication system Technical Field

[0001] The embodiments of the present application relate to the field of communication technologies. Background Art

[0002] Network-controlled mobility applies to connected terminals and can be divided into two types of mobility: cell-level mobility and beam-level mobility. Cell-level mobility can be based on Layer 3 or Layer 1 / 2.

[0003] Layer 3 based mobility:

[0004] Serving cell changes are triggered by L3 measurements and completed by Radio Resource Control (RRC) signalling, with Reconfiguration with Synchronisation triggered for changes in the Primary Cell (PCell) and Primary Secondary Cell (PSCell), and the release of Secondary Cells (SCells) when applicable. Cell-level mobility is triggered by explicit RRC signalling, i.e. handover. The RRC-triggered handover mechanism requires the terminal device (e.g. User Equipment UE) to at least reset the Medium Access Control (MAC) entity and re-establish the Radio Link Control (RLC). RRC-managed handovers are supported with and without re-establishment of the Packet Data Convergence Protocol (PDCP) entity. For Radio Data Bearers (DRBs) using RLC AM mode, PDCP can either re-establish with security key update or initiate a data recovery procedure without key update. For DRBs using RLC UM mode, PDCP can either re-establish with security key update or remain unchanged without key update. For signaling radio bearers (SRBs), PDCP can remain unchanged without key update, discard stored PDCP packet data units / signaling data units (PDUs / SDUs), or re-establish with security key update.

[0005] Layer 1 / 2 based mobility:

[0006] For RRC-triggered handover mechanisms, all cases involve a complete Layer 2 and Layer 1 (L2 / L1) reset, resulting in higher latency, greater overhead, and longer disruption than beam switching mobility. The goal of L1 / L2 mobility enhancement is to ensure that serving cell changes via L1 / L2 signaling reduce latency, overhead, and disruption.

[0007] Layer 1 / 2 Triggered Mobility (LTM) is a process in which a network device (e.g., a gNB) receives Layer 1 measurement reports from a UE. Based on these reports, the gNB changes the UE's serving cell via a cell switch command sent via a Media Access Control Element (MAC CE). The MAC-triggered cell change mechanism (i.e., LTM cell change) requires the UE to at least reset the MAC entity. The RLC handling depends on the network configuration.

[0008] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art.

[0009] Summary of the Invention

[0010] The inventors of this application discovered that current LTM operations only support inter-cell mobility within the same gNB (same CU). If LTM is to be performed between network devices, such as inter-CU LTM, the location of the Packet Data Convergence Protocol (PDCP) entity on the network side changes, but the Layer 2 processing in the current LTM cell change implementation is not applicable to this scenario. This situation significantly limits the opportunities for using LTM.

[0011] In response to at least one of the above problems or other similar problems, embodiments of the present application provide a communication method, a communication device, and a communication system.

[0012] According to one aspect of an embodiment of the present application, a communication apparatus is provided, applied to a terminal device, the apparatus including a first processing unit, the first processing unit causing the terminal device to perform the following operations:

[0013] receiving instruction information sent by the network device; and

[0014] For the layer 1 / layer 2 triggered mobility (LTM) cell change process, the terminal device performs a first process according to the indication information, and the first process includes at least packet data convergence protocol (PDCP) data recovery and / or packet data convergence protocol (PDCP) entity reconstruction.

[0015] According to another aspect of an embodiment of the present application, a communication apparatus is provided, applied to a network device, the apparatus including a second processing unit, the second processing unit causing the network device to perform the following operations:

[0016] The network device sends instruction information to the terminal device,

[0017] Among them, for the layer 1 / layer 2 triggered mobility (LTM) cell change process, the terminal device performs a first processing according to the indication information, and the first processing includes at least packet data convergence protocol (PDCP) data recovery and / or packet data convergence protocol (PDCP) entity reconstruction.

[0018] One of the beneficial effects of the embodiments of the present application is that the technical solution of the present application can be applied to situations where the location of the PDCP entity on the network side changes, thereby expanding the usage scenarios of LTM, which on the one hand improves the flexibility of the mobility method; on the other hand, since more cell changes are achieved through LTM cell changes with smaller interruption delays, the system throughput is improved.

[0019] With reference to the following description and accompanying drawings, specific embodiments of the present application are disclosed in detail, indicating the manner in which the principles of the present application can be employed. It should be understood that the embodiments of the present application are not limited in scope. Within the spirit and scope of the appended claims, the embodiments of the present application include many variations, modifications and equivalents.

[0020] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0021] It should be emphasized that the term "include / comprising" when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The elements and features described in one figure or one embodiment of the present application can be combined with the elements and features shown in one or more other figures or embodiments. In addition, in the accompanying drawings, similar reference numerals represent corresponding parts in several figures and can be used to indicate corresponding parts used in more than one embodiment.

[0023] FIG1 is a schematic diagram of a communication system of the present application;

[0024] FIG2 is a schematic diagram of the intra-CU LTM cell change process;

[0025] Figure 3 is a schematic diagram of the inter-CU LTM scenario.

[0026] Figure 4 is a schematic diagram of a gNB-intra-CU LTM scenario;

[0027] FIG5 is a schematic diagram of a communication method according to an embodiment of the first aspect of the present application;

[0028] FIG6 is a schematic diagram of a communication method according to an embodiment of the second aspect;

[0029] FIG7 is a schematic diagram of a communication device according to an embodiment of the third aspect;

[0030] FIG8 is a schematic diagram of a communication device according to an embodiment of the fourth aspect;

[0031] FIG9 is a schematic diagram of an electronic device according to an embodiment of the fifth aspect. DETAILED DESCRIPTION

[0032] The above and other features of the present application will become apparent through the following description with reference to the accompanying drawings. In the description and the accompanying drawings, specific embodiments of the present application are disclosed in detail, which illustrate some embodiments in which the principles of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the present application includes all modifications, variations and equivalents that fall within the scope of the appended claims.

[0033] In the embodiments of the present application, the terms "first", "second", etc. are used to distinguish different elements from the name, but do not indicate the spatial arrangement or temporal order of these elements, and these elements should not be limited by these terms. The term "and / or" includes any one and all combinations of one or more of the associated listed terms. The terms "comprising", "including", "having", etc. refer to the presence of the stated features, elements, components or components, but do not exclude the presence or addition of one or more other features, elements, components or components.

[0034] In the embodiments of this application, the singular forms "a," "the," etc. include plural forms and should be broadly understood to mean "a" or "a type" rather than being limited to "one." Furthermore, the term "said" should be understood to include both singular and plural forms, unless the context clearly indicates otherwise. Furthermore, the term "according to" should be understood to mean "at least in part based on...", and the term "based on" should be understood to mean "at least in part based on...", unless the context clearly indicates otherwise.

[0035] In the embodiments of the present application, the term "communication network" or "wireless communication network" may refer to a network that complies with any of the following communication standards, such as New Radio (NR), Long Term Evolution (LTE), Enhanced Long Term Evolution (LTE-A, LTE-Advanced), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), etc.

[0036] Furthermore, communication between devices in the communication system may be carried out according to communication protocols of any stage, for example, including but not limited to the following communication protocols: 1G (generation), 2G, 2.5G, 2.75G, 3G, 4G, 4.5G and 5G, New Radio (NR), etc., and / or other communication protocols currently known or to be developed in the future.

[0037] In the embodiments of the present application, the term "network device" refers to, for example, a device in a communication system that connects a terminal device to a communication network and provides services for the terminal device. Network devices may include, but are not limited to, the following devices: an integrated access and backhaul node (IAB-node), a base station (BS), an access point (AP), a transmission reception point (TRP), a broadcast transmitter, a mobile management entity (MME), a gateway, a server, a radio network controller (RNC), a base station controller (BSC), and the like.

[0038] Base stations may include, but are not limited to, NodeB (NB), evolved NodeB (eNodeB or eNB), and 5G base stations (gNB), among others. They may also include remote radio heads (RRHs), remote radio units (RRUs), relays, or low-power nodes (e.g., femeto, pico, etc.). The term "base station" may include some or all of their functions, and each base station may provide communication coverage for a specific geographic area. The term "cell" may refer to a base station and / or its coverage area, depending on the context in which the term is used.

[0039] In the embodiments of the present application, the term "user equipment" (UE) or "terminal equipment" (TE) refers to, for example, a device that accesses a communication network through a network device and receives network services. A terminal device can be fixed or mobile and may also be referred to as a mobile station (MS), a terminal, a subscriber station (SS), an access terminal (AT), a station, and so on.

[0040] Among them, terminal devices may include but are not limited to the following devices: cellular phones, personal digital assistants (PDAs), wireless modems, wireless communication devices, handheld devices, machine-type communication devices, laptop computers, cordless phones, smart phones, smart watches, digital cameras, etc.

[0041] For another example, in scenarios such as the Internet of Things (IoT), the terminal device can also be a machine or device for monitoring or measurement, including but not limited to: machine type communication (MTC) terminal, vehicle-mounted communication terminal, device-to-device (D2D) terminal, machine-to-machine (M2M) terminal, and so on.

[0042] In addition, the term "network side" or "network device side" refers to one side of the network, which can be a base station or one or more network devices as mentioned above. The term "user side" or "terminal side" or "terminal device side" refers to the user or terminal side, which can be a UE or one or more terminal devices as mentioned above.

[0043] In the following description, the terms "uplink control signal" and "uplink control information (UCI)" or "physical uplink control channel (PUCCH)" are interchangeable, and the terms "uplink data signal" and "uplink data information" or "physical uplink shared channel (PUSCH)" are interchangeable to avoid confusion.

[0044] The terms "downlink control signal" and "downlink control information (DCI)" or "physical downlink control channel (PDCCH)" are interchangeable, and the terms "downlink data signal" and "downlink data information" or "physical downlink shared channel (PDSCH)" are interchangeable.

[0045] In addition, sending or receiving PUSCH can be understood as sending or receiving uplink data carried by PUSCH, sending or receiving PUCCH can be understood as sending or receiving uplink information carried by PUCCH, and sending or receiving PRACH can be understood as sending or receiving preamble carried by PRACH; uplink signals can include uplink data signals and / or uplink control signals, etc., and can also be referred to as uplink transmission (UL transmission) or uplink information or uplink channels. Sending uplink transmission on uplink resources can be understood as sending the uplink transmission using the uplink resources. Similarly, downlink data / signals / channels / information can be understood accordingly.

[0046] In the embodiments of the present application, the high-layer signaling may be, for example, radio resource control (RRC) signaling; for example, an RRC message, including, for example, MIB, system information, or a dedicated RRC message; or an RRC information element (RRC IE). The high-layer signaling may also be, for example, MAC (Medium Access Control) signaling; or a MAC control element (MAC CE). However, the present application is not limited thereto.

[0047] The following describes the scenarios of the embodiments of the present application through examples, but the present application is not limited thereto.

[0048] Figure 1 is a schematic diagram of the communication system of the present application, which schematically illustrates the situation taking a terminal device and a network device as an example. As shown in Figure 1, the communication system 100 may include network devices 101, 103 and a terminal device 102 (for simplicity, Figure 1 only illustrates one terminal device as an example).

[0049] In an embodiment of the present application, the terminal device 102 may communicate with one of the network devices 101 and 103 in sequence. Taking the communication between the terminal device 102 and the network device 101 as an example, existing services or future services that can be implemented can be carried out between the network device 101 and the terminal device 102. For example, these services include but are not limited to: enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable and low-latency communication (URLLC), etc.

[0050] Among them, the terminal device 102 can send data to the network device 101, for example, using authorization (for example, a configured authorization, i.e., a configured grant) or an authorization-free transmission mode. In the authorization mode, the network device 101 can receive data sent by one or more terminal devices 102 in the authorization, and feedback information to the terminal device 102, such as confirmation ACK / non-confirmation NACK information, etc., or indicate a new authorization to the terminal device 102. The terminal device 102 can confirm the end of the transmission process based on the feedback information or the new authorization, or can also perform new data transmission, or can retransmit the data. For the authorization-free transmission mode, the terminal device can transmit new data on the configured authorization, or can retransmit.

[0051] Figure 2 is a schematic diagram of the intra-CU LTM cell change process. The basic process on the air interface applies to both Master Cell Group (MCG) LTM and Secondary Cell Group (SCG) LTM. As shown in Figure 2, the intra-CU LTM process includes the following steps:

[0052] 1. The UE in RRC_CONNECTED state sends a MeasurementReport message to the gNB. The gNB decides to configure LTM and initiates candidate cell configuration.

[0053] 2. The gNB sends an RRCReconfiguration message including the LTM candidate cell configuration to the UE.

[0054] 3. The UE stores the LTM candidate cell configuration and sends an RRCReconfigurationComplete message to the gNB.

[0055] 4a. Before receiving the cell change command, the UE performs downlink (DL) synchronization of the candidate cell. This downlink synchronization can be triggered by the gNB. The UE can activate and deactivate the TCI state of the LTM candidate cell.

[0056] 4b. Before receiving the cell change command, the UE performs uplink (UL) synchronization of the candidate cell by using UE-based TA measurement (if configured) and / or by sending a preamble to the candidate cell triggered by the gNB. When UE-based TA measurement is configured, the UE obtains the TA value of the candidate cell through measurement. Before receiving the cell change command, the UE performs early TA acquisition of the candidate cell as requested by the network. This is done by a CFRA triggered by the PDCCH order of the source cell and the subsequent UE sending a preamble to the indicated candidate cell. In order to minimize data interruption to the source cell caused by the CFRA to the candidate cell, the UE does not receive a random access response from the network to obtain the TA value of the candidate cell indicated in the cell handover command. The UE does not maintain a TA timer for the candidate cell and relies on the network to ensure TA validity;

[0057] 5. The UE performs L1 measurements on the configured candidate cells and sends an L1 measurement report to the gNB, where L1 measurements should be performed whenever RRC reconfiguration (i.e., step 2) applies.

[0058] 6. The gNB decides to perform a cell change to the target cell and triggers the cell change by sending a LTM cell change MAC CE including a target configuration ID indicating the candidate configuration index of the target cell, the beam indicated by the TCI state or DL ​​and UL TCI states, and the timing advance command of the target cell, if applicable. The UE switches to the target cell and applies the configuration indicated by the candidate configuration ID.

[0059] 7. If the UE does not have a valid TA for the target cell, the UE performs a random access procedure to the target cell;

[0060] 8. The UE completes the LTM cell change procedure by sending an RRCReconfigurationComplete message to the target cell. If the UE has already performed a random access procedure in step 7, the UE considers the LTM cell change to be successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE considers the LTM cell change to be successfully completed when it determines that the network has successfully received its first UL data.

[0061] For subsequent LTM, steps 4a-8 may be performed multiple times using the LTM candidate configuration provided in step 2. That is, subsequent LTM is achieved by repeating the early synchronization, LTM cell change execution, and LTM cell change completion steps without releasing other LTM candidate configurations after each LTM cell change is completed.

[0062] LTM cell switch execution includes:

[0063] For each signaling radio bearer or data radio bearer (SRB / DRB) in the current UE configuration:

[0064] If the LTM cell change is triggered on the MCG and for an SRB / DRB using a master key; or

[0065] If the LTM cell change is triggered on the SCG, and for SRB / DRB using secondary keys:

[0066] Preserve associated RLC, PDCP and SDAP entities, their state variables, buffers and timers;

[0067] Release all fields related to the SRB / DRB configuration, except srb-Identity and drb-Identity.

[0068] If this procedure is triggered after cell selection while timer T311 is running (due to synchronization reconfiguration failure):

[0069] Continue to use PDCP using SRB1 (if configured) using continuous entity state variables;

[0070] Release / clear all current dedicated radio configurations associated with the cell group triggered by the LTM cell change procedure, except for the following:

[0071] - The logicalChannelIdentity and logicalChannelIdentityExt of the Radio Link Control (RLC) bearer, their state variables, buffers, and timers configured in RLC-BearerConfig;

[0072] -UE variables VarLTM-ServingCellNoResetID and VarLTM-ServingCellUE-MeasuredTA-ID;

[0073] -ltm-Config

[0074] If the LTM cell change is triggered on the MCG:

[0075] -Master Cell Group Cell Radio Network Temporary Identity (MCG C-RNTI);

[0076] - The service-based access stratum (AS) security configuration associated with the master key.

[0077] Otherwise, if the LTM cell change is triggered on the SCG:

[0078] -AS security configuration associated with the secondary key.

[0079] Release / clear all current public radio configurations associated with the cell group triggered by the LTM cell change process;

[0080] Use the default values ​​of timers T310, T311 and constants 310, N311 associated with the cell group triggered by the LTM cell change procedure;

[0081] Use the default MAC cell group configuration of the cell group triggered by the LTM cell change procedure;

[0082] For each signaling radio bearer identity (srb-Identity) in the current UE configuration:

[0083] If the value of the ltm-NoResetID field included in the LTM-Candidate IE in the ltm-Config is not equal to the value of the ltm-ServingCellNoResetID in VarLTM-ServingCellNoResetID:

[0084] For each logicalChannelIdentity and logicalChannelIdentityExt that is part of the current UE configuration for the cell group triggered by this LTM cell change procedure:

[0085] If servedRadioBearer is set to data radio bearer identity (drb-Identity):

[0086] After the process is completed, the LTM configuration in the ltm-CandidateConfig in the LTM-Candidate IE in the ltm-Config is applied and the corresponding RLC entity is rebuilt;

[0087] For each drb-Identity value that is part of the current UE configuration:

[0088] If the DRB is an AM DRB:

[0089] After this process is completed, the LTM configuration in the ltm-CandidateConfig in the LTM-Candidate IE in the ltm-Config is applied, triggering the PDCP entity of this DRB to perform data recovery;

[0090] Replace the value of ltm-ServingCellNoResetID in VarLTM-ServingCellNoResetID with the value of ltm-NoResetID in LTM-Candidate in ltm-Config.

[0091] In this way, during LTM cell change execution, the UE can determine the L2 behavior according to the above content.

[0092] Additionally, network configuration that determines L2 behavior includes:

[0093] (1) IE LTM-Config includes the ID used to configure the serving cell (The IE LTM-Config is used to provide LTM candidate configurations), as shown in Table 1.

[0094] Table 1

[0095] (2) IE LTM-Candidate includes the ID used to configure candidate cells (The IE LTM-Candidate concerns a LTM candidate configuration to add or modify), as shown in Table 2.

[0096] Table 2

[0097] In addition, for a target cell that is not an LTM candidate cell, the per-radio bearer (Per RB) configuration includes:

[0098] (1) In NR, each radio bearer (DRB or SRB) is configured using the IE RadioBearerConfig, as shown in Tables 3, 4, and 5.

[0099] Table 3

[0100] Table 4

[0101] Table 5

[0102] As indicated above, the network may indicate PDCP re-establishment (if not part of the LTM candidate configuration) or SDU / PDU discard per SRB, and PDCP re-establishment or PDCP data recovery (if not part of the LTM candidate configuration) per DRB.

[0103] (2) NR uses the IE RLC-BearerConfig to configure each RLC entity, as shown in Tables 6 and 7.

[0104] Table 6

[0105] Table 7

[0106] As indicated above, the network may instruct RLC re-establishment per RLC entity (if not part of the LTM candidate configuration).

[0107] Figure 3 is a schematic diagram of the inter-gNB-CU LTM scenario, and Figure 4 is a schematic diagram of the intra-gNB-CU LTM scenario.

[0108] As shown in Figure 3, the UE performs LTM from cell 2 to cell 3, i.e., inter-CU LTM. In inter-CU LTM, the LTM candidate cell configuration includes at least the cell configurations of different CUs; ​​the cell change command (MAC CE) indicates that the candidate cell configuration is associated with an inter-CU cell.

[0109] In addition, the LTM between cell 1 and cell 2, the LTM between cell 3 and cell 4, or the LTM between cell 5 and cell 6 in FIG3 are all intra-CU LTMs.

[0110] As shown in Figure 4, the UE performs inter-cell LTM within the same CU, i.e., intra-CU LTM. In intra-CU LTM, the LTM candidate cell configuration includes at least the cell configuration of the same CU; the cell change command (MAC CE) indicates that the candidate cell configuration is associated with an intra-CU cell.

[0111] Embodiments of the first aspect

[0112] LTM operation only supports inter-cell mobility within the same gNB (same CU). The following scenarios are supported:

[0113] Synchronous reconfiguration of LTM cell change (without security key refresh), and:

[0114] Random access (RA) involving or not involving the target LTM candidate special cell according to the network instruction;

[0115] MAC reset;

[0116] Depends on network indication, i.e., RLC re-establishment and PDCP data resumption (for AM DRBs), or no RLC re-establishment.

[0117] When LTM cell change is performed, if the LTM is triggered on the Master Cell Group (MCG), the UE will not release / clear the service-based access stratum (AS) security configuration associated with the master key, and for each SRB / DRB using the master key in the current UE configuration, the associated Packet Data Convergence Protocol (PDCP) and Service Discovery Application Profile (SDAP) entities and their state variables, caches and timers are kept.

[0118] However, for inter-CU LTM, the location of the PDCP entity on the network side changes, and the L2 processing in the current LTM cell change execution is not applicable.

[0119] In order to solve the above problems or at least similar problems, an embodiment of the first aspect of the present application provides a communication method applied to a terminal device, for example, the terminal device 102 in Figure 1.

[0120] FIG5 is a schematic diagram of a communication method according to an embodiment of the first aspect of the present application. As shown in FIG5 , the communication method includes:

[0121] 501. The terminal device receives instruction information sent by the network device; and

[0122] 502. For the layer 1 / layer 2 triggered mobility (LTM) cell change process, the terminal device performs a first process according to the indication information, and the first process includes at least packet data convergence protocol (PDCP) data recovery and / or packet data convergence protocol (PDCP) entity reconstruction.

[0123] In some embodiments, the first processing is performed by the terminal device on a data radio bearer (DRB) and / or a signaling radio bearer (SRB).

[0124] In some examples, the data radio bearer (DRB) is at least a portion of a data radio bearer (DRB) configured for a current terminal device (UE) of a cell group triggered by the layer 1 / layer 2 triggered mobility (LTM) cell change procedure. In addition, the signaling radio bearer (SRB) is a portion or all of a signaling radio bearer (SRB) configured for the terminal device.

[0125] The data radio bearer (DRB) includes an acknowledged mode data radio bearer (AM DRB) and / or an unacknowledged mode data radio bearer (UM DRB).

[0126] The signaling radio bearer (SRB) includes a signaling radio bearer 1 (SRB1) and / or a signaling radio bearer 2 (SRB2) and / or a signaling radio bearer 3 (SRB3).

[0127] In some embodiments, the layer 1 / layer 2 triggered mobility (LTM) cell change procedure in operation 502 may be triggered by one of the following ways:

[0128] A Layer 1 / Layer 2 Triggered Mobility (LTM) Cell Change Command Media Access Control Element (MAC CE) is triggered by a lower layer, such as a Media Access Control (MAC) layer;

[0129] Triggered by a Layer 1 / Layer 2 triggered mobility (LTM) candidate cell selected in cell selection after handover failure or radio link failure;

[0130] The terminal device determines or evaluates that a trigger condition or an execution condition is satisfied and triggers the trigger.

[0131] In some embodiments, the Layer 1 / Layer 2 Triggered Mobility (LTM) cell change procedure may include:

[0132] ① Cell change execution process; and

[0133] ② After the cell change execution process, the configuration of the target cell, candidate cell or selected cell is applied, or the first process is performed.

[0134] For the above situation ②, the first process may be performed after applying the configuration of the target cell, the candidate cell, or the selected cell.

[0135] In some embodiments, the indication information includes at least one of the following information:

[0136] Safety-related information;

[0137] Inter-CU LTM information;

[0138] A first identifier (ID) used to indicate Layer 2 (L2) or PDCP layer / entity behavior, where Layer 2 includes the Media Access Control layer / Radio Link Control layer / Packet Data Convergence Protocol layer / Service Discovery Application Specification layer (MAC / RLC / PDCP / SDAP).

[0139] In some embodiments, the security-related information includes at least one of the following information:

[0140] An indication of whether it is a safe update;

[0141] An indication of whether the security key has changed, the security key including a primary key and / or a secondary key, wherein, if the LTM cell change process is triggered on the MCG, the security key is the primary key; if the LTM cell change process is triggered on the SCG, the security key is the primary key and / or the secondary key.

[0142] The indication of whether the update is safe includes any of the following situations:

[0143] Case 1: The network device provides an indication message for indicating a security update or indicating no security update;

[0144] Case 2: In the case where a security update is required, the network device provides an indication information indicating the security update, i.e., if the security update is not performed, there is no such indication information;

[0145] Case 3: When security update is not required, the network device provides an indication information indicating that security update is not to be performed, that is, if security update is to be performed, there is no such indication information.

[0146] The indication of whether the security key is updated includes any of the following situations:

[0147] Case 1: The network device provides an indication message for indicating that the security key is updated or not updated;

[0148] Case 2: When a security key update is required, the network device provides an indication information indicating the security key update, i.e., if the security key update is not performed, there is no such indication information;

[0149] Case 3: When the security key update is not required, the network device provides an indication information indicating that the security key update is not to be performed. That is, if the security key update is to be performed, there is no such indication information.

[0150] In some embodiments, the information of the inter-CU layer 1 / layer 2 triggered mobility (Inter-CU LTM) is used to indicate inter-CU layer 1 / layer 2 triggered mobility (Inter-CU LTM), for example, to indicate whether it is Inter-CU LTM.

[0151] The indication of whether it is Inter-CU LTM includes any of the following situations:

[0152] Case 1: The network device provides an indication message for indicating Inter-CU LTM or Intra-CU LTM.

[0153] Case 2: When Inter-CU LTM is required, the network device provides an indication information indicating Inter-CU LTM. That is, if Inter-CU LTM is not performed (or Intra-CU LTM is performed), there is no such indication information.

[0154] Case 3: When Inter-CU LTM is not required, the network device provides an indication information indicating not to perform Inter-CU LTM. That is, if Inter-CU LTM is performed, there is no such indication information.

[0155] In some embodiments, the Inter-CU LTM information is included in at least one of the following information:

[0156] Reference configuration;

[0157] Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configurations;

[0158] Radio Resource Control (RRC) reconfiguration message outside of Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configuration.

[0159] In some embodiments, the Inter-CU LTM information includes:

[0160] The length of the cell identifier (ID) and the network equipment identifier (gNB ID).

[0161] In the case of LTM candidate cell preparation, that is, when the inter-CU LTM information (e.g., cell ID + gNB ID length) is included in at least one of the information described above: the network device must / must / mandatorily indicate the gNB ID length information.

[0162] In some examples, the first identifier (ID) is different from the second identifier (ID), and the second identifier (ID) may be a no reset identifier (No reset ID), such as ltm-ServingCellNoResetID or ltm-NoResetID. For example, the first identifier (ID) is a separate ID other than ltm-ServingCellNoResetID or ltm-NoResetID, or an ID defined by Release 19 (Rel-19). The first identifier (ID) may be the first identifier (ID) of the serving cell and / or the first identifier (ID) of the candidate cell.

[0163] In other examples, the value of the first identifier (ID) is an extended value of the second identifier (ID), and the second identifier (ID) can be a no reset identifier (No reset ID), for example, ltm-ServingCellNoResetID or ltm-NoResetID.

[0164] In some embodiments, the indication information further includes: indication information per radio bearer (RB) and / or per radio link control (RLC) entity.

[0165] In some examples, the per-radio link control (RLC) entity indication information includes a per-RLC indication of radio link control (RLC) entity re-establishment.

[0166] In some other examples, the per-radio bearer (RB) indication information includes a packet data convergence protocol (PDCP) data resumption per-DRB indication.

[0167] In some further examples, the per-radio bearer (RB) indication information includes a per-RB indication of a Packet Data Convergence Protocol (PDCP) entity reestablishment.

[0168] In some further examples, for a signaling radio bearer (SRB), the indication information per radio bearer (RB) includes: an indication per SRB of protocol data units and / or signaling data units (PDUs and / or SDUs) discarded.

[0169] In some embodiments, the indication information in operation 501 is included in a radio resource control (RRC) message or a media access control control element (MAC CE). The radio resource control (RRC) message includes a radio resource control (RRC) reconfiguration message for configuring layer 1 / layer 2 triggered mobility (LTM) candidate configuration or serving cell configuration. In addition, the media access control control element (MAC CE) is a layer 1 / layer 2 triggered mobility (LTM) cell change command media access control control element (MAC CE), or a media access control control element (MAC CE) for security or inter-central unit (inter-CU) LTM or layer 2 (L2) processing.

[0170] In operation 502, the terminal device performs the first process according to the instruction information, including three solutions:

[0171] Solution 1 corresponds to the case where the network indication is the first ID for indicating L2 behavior;

[0172] Solution 2 corresponds to the case where the network indication is security-related information;

[0173] Solution 3 corresponds to the case where the network indication is Inter-CU LTM information.

[0174] In solution 1, if the first identifier (ID) of the target cell or candidate cell is the same as the first identifier (ID) of the serving cell or source cell, the terminal device performs the following operations:

[0175] Performing a media access control (MAC) reestablishment, and further, if the first identifier (ID) is different from the second identifier (ID), the network device does not include or the terminal device ignores the second identifier (ID); or

[0176] performing a medium access control (MAC) re-establishment, a radio link control (RLC) re-establishment (e.g., according to an indication per RLC entity), and a packet data convergence protocol (PDCP) data recovery (e.g., according to an indication per DRB), and further, if the first identifier (ID) is different from the second identifier (ID), the network device does not include, or the terminal device ignores, the second identifier (ID); or

[0177] When the second identifier (ID) of the target cell or candidate cell is the same as the second identifier (ID) of the serving cell or source cell, perform media access control (MAC) re-establishment; when the second identifier (ID) of the target cell or candidate cell is different from the second identifier (ID) of the serving cell or source cell, perform media access control (MAC) re-establishment, radio link control (RLC) re-establishment (e.g., according to an indication per RLC entity), and packet data convergence protocol (PDCP) data recovery (e.g., according to an indication per DRB). This operation is applicable when the first identifier (ID) is different from the second identifier (ID).

[0178] In solution 1, if the first identifier (ID) of the target cell or candidate cell is different from the first identifier (ID) of the serving cell or source cell, the terminal device performs the packet data convergence protocol (PDCP) entity re-establishment (for example, according to the indication of each radio bearer RB), the medium access control (MAC) re-establishment and the radio link control (RLC) re-establishment (for example, according to the indication of each RLC entity). The first identifier (ID) of the serving cell or source cell is the first identifier (ID) stored in the terminal device, or the first identifier (ID) in the current UE configuration.

[0179] In some examples of Scheme 2, if the terminal device is configured with an indication of security update or is instructed to perform a security update, or is configured with an indication of security key change or is instructed to perform a security key change, the terminal device performs the Packet Data Convergence Protocol (PDCP) entity reconstruction (e.g., based on an indication per RB), Medium Access Control (MAC) reconstruction, and Radio Link Control (RLC) reconstruction (e.g., based on an indication per RLC entity).

[0180] In some other examples of Solution 2, if the terminal device is not configured with a security update indication or is instructed not to update security, or is not configured with a security key change indication or is instructed not to change security keys, the terminal device:

[0181] Performing a media access control (MAC) re-establishment, furthermore, the network device does not include or the terminal device ignores the second identification (ID); or

[0182] performing a medium access control (MAC) re-establishment, a radio link control (RLC) re-establishment (e.g., according to an indication per RLC entity), and a packet data convergence protocol (PDCP) data recovery (e.g., according to an indication per DRB), and further, the network device does not include, or the terminal device ignores, a second identifier (ID); or

[0183] When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, perform media access control (MAC) re-establishment; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, perform media access control (MAC) re-establishment, radio link control (RLC) re-establishment (for example, according to the indication of each RLC entity) and packet data convergence protocol (PDCP) data recovery (for example, according to the indication of each DRB).

[0184] In some examples of scheme 3, if the terminal device is configured with central unit inter-layer 1 / layer 2 triggered mobility (Inter-CU LTM) or is indicated for central unit inter-layer 1 / layer 2 triggered mobility (Inter-CU LTM), or the network equipment identifier (gNB ID) of the target cell or candidate cell is different from the network equipment identifier (gNB ID) of the serving cell or source cell, the terminal device performs the packet data convergence protocol (PDCP) entity re-establishment (e.g., according to the indication of each RB), medium access control (MAC) re-establishment and radio link control (RLC) re-establishment (e.g., according to the indication of each RLC entity).

[0185] In other examples of Solution 3, if the terminal device is not configured with Inter-CU LTM or is not instructed with Inter-CU LTM, or the network equipment identifier (gNB ID) of the target cell or candidate cell is the same as the network equipment identifier (gNB ID) of the serving cell or source cell, the terminal device:

[0186] Performing a media access control (MAC) re-establishment, furthermore, the network device does not include or the terminal device ignores the second identification (ID); or

[0187] Performing medium access control (MAC) re-establishment, radio link control (RLC) re-establishment, and packet data convergence protocol (PDCP) data recovery, and further, the network device does not include or the terminal device ignores the second identifier (ID); or

[0188] When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, perform media access control (MAC) re-establishment; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, perform media access control (MAC) re-establishment, radio link control (RLC) re-establishment (e.g., according to the indication of each RLC entity) and packet data convergence protocol (PDCP) data recovery (e.g., according to the indication of each DRB).

[0189] In some embodiments, when the first processing is performed on a DRB or SRB, corresponding processing can be performed based on the indication information of each radio bearer (RB) and / or each radio link control (RLC) entity provided for the DRB or SRB.

[0190] In some examples, if radio link control (RLC) entity reestablishment is indicated or configured in the radio link control (RLC) configuration associated with the radio bearer (RB), the first process includes radio link control (RLC) entity reestablishment. In other examples, if packet data convergence protocol (PDCP) data resumption is indicated or configured in the radio bearer (RB) configuration of a data radio bearer (DRB), the first process includes packet data convergence protocol (PDCP) data resumption. In still other examples, if entity reestablishment is indicated or configured in the radio bearer (RB) configuration of a data radio bearer (DRB) or a signaling radio bearer (SRB), the first process includes packet data convergence protocol (PDCP) entity reestablishment.

[0191] In some further examples, for a signaling radio bearer (SRB), the first processing also includes: if protocol data unit and / or signaling data unit (PDU and / or SDU) discard is indicated or configured in the radio bearer (RB) configuration of the signaling radio bearer (SRB), then the first processing includes discarding the protocol data unit and / or signaling data unit (PDU and / or SDU).

[0192] The technical solution of the embodiment of the first aspect of the present application can be applied to the situation where the location of the PDCP entity on the network side changes, thereby expanding the use scenarios of LTM and improving flexibility.

[0193] Embodiments of the second aspect

[0194] The second embodiment of the present application provides a communication method, which is applied to a network device. The method corresponds to the communication method of the first embodiment.

[0195] As shown in FIG6 , the communication method of the embodiment of the second aspect includes:

[0196] 601. The network device sends an indication message to the terminal device, wherein, for a layer 1 / layer 2 triggered mobility (LTM) cell change process, the indication message causes the terminal device to perform a first process, the first process including at least packet data convergence protocol (PDCP) data recovery and / or packet data convergence protocol (PDCP) entity reconstruction.

[0197] In some embodiments, the first processing is performed by the terminal device on a data radio bearer (DRB) and / or a signaling radio bearer (SRB).

[0198] In some embodiments, the layer 1 / layer 2 triggered mobility (LTM) cell change procedure is triggered by one of the following ways:

[0199] The Layer 1 / Layer 2 Triggered Mobility (LTM) Cell Change Command Media Access Control Element (MAC CE) is received by the lower layers;

[0200] Triggered by a Layer 1 / Layer 2 triggered mobility (LTM) candidate cell selected in cell selection after handover failure or radio link failure;

[0201] The terminal device is triggered when it determines that a trigger condition or an execution condition is met.

[0202] In some embodiments, the layer 1 / layer 2 triggered mobility (LTM) cell change procedure includes:

[0203] Cell change execution process; and

[0204] After the cell change execution process, the configuration of the target cell, candidate cell, or selected cell is applied, or the first process is performed.

[0205] In some embodiments, after applying the configuration of the target cell or the candidate cell or the selected cell, the terminal device performs the first processing.

[0206] In some embodiments, the indication information includes at least one of the following information:

[0207] Safety-related information;

[0208] Inter-CU LTM information;

[0209] A first identifier (ID) indicating layer 2 (L2) behavior.

[0210] In some embodiments, the security-related information includes at least one of the following information:

[0211] An indication of whether it is a safe update;

[0212] An indication of whether security keys have changed, the security keys including primary keys and / or secondary keys.

[0213] In some embodiments, the inter-CU layer 1 / layer 2 triggered mobility (Inter-CU LTM) information is used to indicate inter-CU layer 1 / layer 2 triggered mobility (Inter-CU LTM), and the information is included in at least one of the following information:

[0214] Reference configuration;

[0215] Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configurations;

[0216] Radio Resource Control (RRC) reconfiguration message outside of Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configuration.

[0217] In some embodiments, the Inter-CU LTM information includes:

[0218] The length of the cell identifier (ID) and the network equipment identifier (gNB ID).

[0219] In some embodiments, the first identification (ID) is different from the second identification (ID); or

[0220] The value of the first identifier (ID) is an extended value of the second identifier (ID),

[0221] The second identifier is a no-reset identifier (ID).

[0222] In some embodiments, the indication information is included in a radio resource control (RRC) message or a medium access control element (MAC CE).

[0223] In some embodiments, the radio resource control (RRC) message includes a radio resource control (RRC) reconfiguration message for configuring layer 1 / layer 2 triggered mobility (LTM) candidate configuration or serving cell configuration; and / or

[0224] The media access control control element (MAC CE) is a layer 1 / layer 2 triggered mobility (LTM) cell change command media access control control element (MAC CE), or a media access control control element (MAC CE) for security or inter-central unit (inter-CU) LTM or layer 2 (L2) processing.

[0225] In addition, in the embodiment of the second aspect, for further description of the indication information, reference can be made to the description in the embodiment of the first aspect.

[0226] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0227] If the first identifier (ID) of the target cell or the candidate cell is the same as the first identifier (ID) of the serving cell or the source cell, the terminal device:

[0228] Performing a Medium Access Control (MAC) re-establishment; or

[0229] Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or

[0230] When the second identifier (ID) of the target cell or candidate cell is the same as the second identifier (ID) of the serving cell or source cell, media access control (MAC) reconstruction is performed; when the second identifier (ID) of the target cell or candidate cell is different from the second identifier (ID) of the serving cell or source cell, media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery are performed.

[0231] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0232] If the first identifier (ID) of the target cell or candidate cell is different from the first identifier (ID) of the serving cell or source cell, the terminal device performs the packet data convergence protocol (PDCP) entity reconstruction, media access control (MAC) reconstruction and radio link control (RLC) reconstruction.

[0233] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0234] If the terminal device is configured with a security update indication or is instructed to perform a security update, or is configured with a security key change indication or is instructed to perform a security key change,

[0235] The terminal device performs the Packet Data Convergence Protocol (PDCP) entity reconstruction, Medium Access Control (MAC) reconstruction and Radio Link Control (RLC) reconstruction.

[0236] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0237] If the terminal device is not configured with a security update instruction or is instructed not to update security, or is not configured with a security key change instruction or is instructed not to change security keys,

[0238] The terminal device:

[0239] Performing a Medium Access Control (MAC) re-establishment; or

[0240] Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or

[0241] When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, perform media access control (MAC) reconstruction; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, perform media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery.

[0242] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0243] If the terminal device is configured with Inter-CU LTM or is instructed to use Inter-CU LTM, or the gNB ID of the target cell or candidate cell is different from the gNB ID of the serving cell or source cell,

[0244] The terminal device performs the Packet Data Convergence Protocol (PDCP) entity reconstruction, Medium Access Control (MAC) reconstruction and Radio Link Control (RLC) reconstruction.

[0245] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0246] If the terminal device is not configured with Inter-CU LTM or is not instructed to use Inter-CU LTM, or the gNB ID of the target cell or candidate cell is the same as the gNB ID of the serving cell or source cell,

[0247] The terminal device:

[0248] Performing a Medium Access Control (MAC) re-establishment; or

[0249] Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or

[0250] When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, media access control (MAC) reconstruction is performed; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery are performed.

[0251] In some embodiments, the indication information further includes: indication information per radio bearer (RB) and / or per radio link control (RLC) entity.

[0252] In some embodiments, the indication information per radio link control (RLC) entity includes an indication of radio link control (RLC) entity reestablishment, and if radio link control (RLC) entity reestablishment is indicated or configured in the radio link control (RLC) configuration associated with the radio bearer (RB), the first processing includes radio link control (RLC) entity reestablishment; and / or

[0253] The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) data recovery, and if packet data convergence protocol (PDCP) data recovery is indicated or configured in the radio bearer (RB) configuration of the data radio bearer (DRB), the first processing includes packet data convergence protocol (PDCP) data recovery; and / or

[0254] The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) entity reconstruction. If entity reconstruction is indicated or configured in the radio bearer (RB) configuration of the data radio bearer (DRB) or the signaling radio bearer (SRB), the first processing includes packet data convergence protocol (PDCP) entity reconstruction.

[0255] In some embodiments, for the signaling radio bearer (SRB), the first processing further includes protocol data unit and / or signaling data unit (PDU and / or SDU) discarding.

[0256] In some embodiments, the data radio bearer (DRB) is a data radio bearer (DRB) of at least part of a current terminal equipment (UE) configuration of a cell group triggered by the layer 1 / layer 2 triggered mobility (LTM) cell change procedure; and / or

[0257] The signaling radio bearer (SRB) is part or all of the signaling radio bearers (SRBs) configured for the terminal device.

[0258] In some embodiments, the data radio bearer (DRB) includes an acknowledged mode data radio bearer (AM DRB) and / or an unacknowledged mode data radio bearer (UM DRB);

[0259] The signaling radio bearer (SRB) includes signaling radio bearer 1 (SRB1) and / or signaling radio bearer 2 (SRB2) and / or signaling radio bearer 3 (SRB3).

[0260] Embodiments of the third aspect

[0261] The third embodiment of the present application provides a communication device, which is applied to a terminal device. The device corresponds to the communication method of the first embodiment.

[0262] FIG7 is a schematic diagram of a communication device in an embodiment of the third aspect. As shown in FIG7 , the communication device 700 includes a first processing unit 701. The first processing unit 701 controls the terminal device so that the terminal device performs the following operations:

[0263] receiving instruction information sent by the network device; and

[0264] For the layer 1 / layer 2 triggered mobility (LTM) cell change process, the terminal device performs a first process according to the indication information, and the first process includes at least packet data convergence protocol (PDCP) data recovery and / or packet data convergence protocol (PDCP) entity reconstruction.

[0265] In some embodiments, the first processing is performed by the terminal device on a data radio bearer (DRB) and / or a signaling radio bearer (SRB).

[0266] In some embodiments, the layer 1 / layer 2 triggered mobility (LTM) cell change procedure is triggered by one of the following ways:

[0267] The Layer 1 / Layer 2 Triggered Mobility (LTM) Cell Change Command Media Access Control Element (MAC CE) is received by the lower layers;

[0268] Triggered by a Layer 1 / Layer 2 triggered mobility (LTM) candidate cell selected in cell selection after handover failure or radio link failure;

[0269] The terminal device is triggered when it determines that a trigger condition or an execution condition is met.

[0270] In some embodiments, the layer 1 / layer 2 triggered mobility (LTM) cell change procedure includes:

[0271] Cell change execution process; and

[0272] After the cell change execution process, the configuration of the target cell, candidate cell, or selected cell is applied, or the first process is performed.

[0273] In some embodiments, the first process is performed after applying the configuration of the target cell or the candidate cell or the selected cell.

[0274] In some embodiments, the indication information includes at least one of the following information:

[0275] Safety-related information;

[0276] Inter-CU LTM information;

[0277] A first identifier (ID) indicating layer 2 (L2) behavior.

[0278] In some embodiments, the security-related information includes at least one of the following information:

[0279] An indication of whether it is a safe update;

[0280] An indication of whether security keys have changed, the security keys including primary keys and / or secondary keys.

[0281] In some embodiments, the inter-CU layer 1 / layer 2 triggered mobility (Inter-CU LTM) information is used to indicate inter-CU layer 1 / layer 2 triggered mobility (Inter-CU LTM), and the information is included in at least one of the following information:

[0282] Reference configuration;

[0283] Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configurations;

[0284] Radio Resource Control (RRC) reconfiguration message outside of Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configuration.

[0285] In some embodiments, the Inter-CU LTM information includes:

[0286] The length of the cell identifier (ID) and the network equipment identifier (gNB ID).

[0287] In some embodiments, the first identification (ID) is different from the second identification (ID); or

[0288] The value of the first identifier (ID) is an extended value of the second identifier (ID),

[0289] The second identifier is a no-reset identifier (ID).

[0290] In some embodiments, the indication information is included in a radio resource control (RRC) message or a medium access control element (MAC CE).

[0291] In some embodiments, the radio resource control (RRC) message includes a radio resource control (RRC) reconfiguration message for configuring layer 1 / layer 2 triggered mobility (LTM) candidate configuration or serving cell configuration; and / or

[0292] The media access control control element (MAC CE) is a layer 1 / layer 2 triggered mobility (LTM) cell change command media access control control element (MAC CE), or a media access control control element (MAC CE) for security or inter-central unit (inter-CU) LTM or layer 2 (L2) processing.

[0293] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0294] If the first identifier (ID) of the target cell or the candidate cell is the same as the first identifier (ID) of the serving cell or the source cell, the terminal device:

[0295] Performing a Medium Access Control (MAC) re-establishment; or

[0296] Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or

[0297] When the second identifier (ID) of the target cell or the candidate cell is the same as the second identifier (ID) of the serving cell or the source cell, media access control (MAC) reconstruction is performed; when the second identifier (ID) of the target cell or the candidate cell is different from the second identifier (ID) of the serving cell or the source cell, media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery are performed.

[0298] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0299] If the first identifier (ID) of the target cell or candidate cell is different from the first identifier (ID) of the serving cell or source cell, the terminal device performs the packet data convergence protocol (PDCP) entity reconstruction, media access control (MAC) reconstruction and radio link control (RLC) reconstruction.

[0300] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0301] If the terminal device is configured with a security update indication or is instructed to perform a security update, or is configured with a security key change indication or is instructed to perform a security key change,

[0302] The terminal device performs the Packet Data Convergence Protocol (PDCP) entity reconstruction, Medium Access Control (MAC) reconstruction and Radio Link Control (RLC) reconstruction.

[0303] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0304] If the terminal device is not configured with a security update instruction or is instructed not to update security, or is not configured with a security key change instruction or is instructed not to change security keys,

[0305] The terminal device:

[0306] Performing a Medium Access Control (MAC) re-establishment; or

[0307] Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or

[0308] When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, perform media access control (MAC) reconstruction; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, perform media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery.

[0309] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0310] If the terminal device is configured with Inter-CU LTM or is instructed to use Inter-CU LTM, or the gNB ID of the target cell or candidate cell is different from the gNB ID of the serving cell or source cell,

[0311] The terminal device performs the Packet Data Convergence Protocol (PDCP) entity reconstruction, Medium Access Control (MAC) reconstruction and Radio Link Control (RLC) reconstruction.

[0312] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0313] If the terminal device is not configured with Inter-CU LTM or is not instructed to use Inter-CU LTM, or the gNB ID of the target cell or candidate cell is the same as the gNB ID of the serving cell or source cell,

[0314] The terminal device:

[0315] Performing a Medium Access Control (MAC) re-establishment; or

[0316] Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or

[0317] When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, media access control (MAC) reconstruction is performed; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery are performed.

[0318] In some embodiments, the indication information further includes: indication information per radio bearer (RB) and / or per radio link control (RLC) entity.

[0319] In some embodiments, the indication information per radio link control (RLC) entity includes an indication of radio link control (RLC) entity reestablishment, and if radio link control (RLC) entity reestablishment is indicated or configured in the radio link control (RLC) configuration associated with the radio bearer (RB), the first processing includes radio link control (RLC) entity reestablishment; and / or

[0320] The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) data recovery, and if packet data convergence protocol (PDCP) data recovery is indicated or configured in the radio bearer (RB) configuration of the data radio bearer (DRB), the first processing includes packet data convergence protocol (PDCP) data recovery; and / or

[0321] The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) entity reconstruction. If entity reconstruction is indicated or configured in the radio bearer (RB) configuration of the data radio bearer (DRB) or the signaling radio bearer (SRB), the first processing includes packet data convergence protocol (PDCP) entity reconstruction.

[0322] In some embodiments, for the signaling radio bearer (SRB), the first processing further includes protocol data unit and / or signaling data unit (PDU and / or SDU) discarding.

[0323] In some embodiments, the data radio bearer (DRB) is a data radio bearer (DRB) of at least part of a current terminal equipment (UE) configuration of a cell group triggered by the layer 1 / layer 2 triggered mobility (LTM) cell change procedure; and / or

[0324] The signaling radio bearer (SRB) is part or all of the signaling radio bearers (SRBs) configured for the terminal device.

[0325] In some embodiments, the data radio bearer (DRB) includes an acknowledged mode data radio bearer (AM DRB) and / or an unacknowledged mode data radio bearer (UM DRB);

[0326] The signaling radio bearer (SRB) includes signaling radio bearer 1 (SRB1) and / or signaling radio bearer 2 (SRB2) and / or signaling radio bearer 3 (SRB3).

[0327] Embodiments of the fourth aspect

[0328] The fourth embodiment of the present application provides a communication device, which is applied to a network device. The device corresponds to the communication method of the second embodiment.

[0329] FIG8 is a schematic diagram of a communication device in an embodiment of the fourth aspect. As shown in FIG8 , the communication device 800 includes a second processing unit 801. The second processing unit 801 controls the network device so that the network device performs the following operations:

[0330] The network device sends an indication message to the terminal device, wherein, for a layer 1 / layer 2 triggered mobility (LTM) cell change process, the indication message causes the terminal device to perform a first process, the first process including at least packet data convergence protocol (PDCP) data recovery and / or packet data convergence protocol (PDCP) entity reconstruction.

[0331] In some embodiments, the first processing is performed by the terminal device on a data radio bearer (DRB) and / or a signaling radio bearer (SRB).

[0332] In some embodiments, the layer 1 / layer 2 triggered mobility (LTM) cell change procedure is triggered by one of the following ways:

[0333] The Layer 1 / Layer 2 Triggered Mobility (LTM) Cell Change Command Media Access Control Element (MAC CE) is received by the lower layers;

[0334] Triggered by a Layer 1 / Layer 2 triggered mobility (LTM) candidate cell selected in cell selection after handover failure or radio link failure;

[0335] The terminal device is triggered when it determines that a trigger condition or an execution condition is met.

[0336] In some embodiments, the layer 1 / layer 2 triggered mobility (LTM) cell change procedure includes:

[0337] Cell change execution process; and

[0338] After the cell change execution process, the configuration of the target cell, candidate cell, or selected cell is applied, or the first process is performed.

[0339] In some embodiments, after applying the configuration of the target cell or the candidate cell or the selected cell, the terminal device performs the first processing.

[0340] In some embodiments, the indication information includes at least one of the following information:

[0341] Safety-related information;

[0342] Inter-CU LTM information;

[0343] A first identifier (ID) indicating layer 2 (L2) behavior.

[0344] In some embodiments, the security-related information includes at least one of the following information:

[0345] An indication of whether it is a safe update;

[0346] An indication of whether security keys have changed, the security keys including primary keys and / or secondary keys.

[0347] In some embodiments, the inter-CU layer 1 / layer 2 triggered mobility (Inter-CU LTM) information is used to indicate inter-CU layer 1 / layer 2 triggered mobility (Inter-CU LTM), and the information is included in at least one of the following information:

[0348] Reference configuration;

[0349] Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configurations;

[0350] Radio Resource Control (RRC) reconfiguration message outside of Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configuration.

[0351] In some embodiments, the Inter-CU LTM information includes:

[0352] The length of the cell identifier (ID) and the network equipment identifier (gNB ID).

[0353] In some embodiments, the first identification (ID) is different from the second identification (ID); or

[0354] The value of the first identifier (ID) is an extended value of the second identifier (ID),

[0355] The second identifier is a no-reset identifier (ID).

[0356] In some embodiments, the indication information is included in a radio resource control (RRC) message or a medium access control element (MAC CE).

[0357] In some embodiments, the radio resource control (RRC) message includes a radio resource control (RRC) reconfiguration message for configuring layer 1 / layer 2 triggered mobility (LTM) candidate configuration or serving cell configuration; and / or

[0358] The media access control control element (MAC CE) is a layer 1 / layer 2 triggered mobility (LTM) cell change command media access control control element (MAC CE), or a media access control control element (MAC CE) for security or inter-central unit (inter-CU) LTM or layer 2 (L2) processing.

[0359] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0360] If the first identifier (ID) of the target cell or the candidate cell is the same as the first identifier (ID) of the serving cell or the source cell, the terminal device:

[0361] Performing a Medium Access Control (MAC) re-establishment; or

[0362] Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or

[0363] When the second identifier (ID) of the target cell or candidate cell is the same as the second identifier (ID) of the serving cell or source cell, media access control (MAC) reconstruction is performed; when the second identifier (ID) of the target cell or candidate cell is different from the second identifier (ID) of the serving cell or source cell, media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery are performed.

[0364] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0365] If the first identifier (ID) of the target cell or candidate cell is different from the first identifier (ID) of the serving cell or source cell, the terminal device performs the packet data convergence protocol (PDCP) entity reconstruction, media access control (MAC) reconstruction and radio link control (RLC) reconstruction.

[0366] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0367] If the terminal device is configured with a security update indication or is instructed to perform a security update, or is configured with a security key change indication or is instructed to perform a security key change,

[0368] The terminal device performs the Packet Data Convergence Protocol (PDCP) entity reconstruction, Medium Access Control (MAC) reconstruction and Radio Link Control (RLC) reconstruction.

[0369] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0370] If the terminal device is not configured with a security update instruction or is instructed not to update security, or is not configured with a security key change instruction or is instructed not to change security keys,

[0371] The terminal device:

[0372] Performing a Medium Access Control (MAC) re-establishment; or

[0373] Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or

[0374] When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, perform media access control (MAC) reconstruction; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, perform media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery.

[0375] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0376] If the terminal device is configured with Inter-CU LTM or is instructed to use Inter-CU LTM, or the gNB ID of the target cell or candidate cell is different from the gNB ID of the serving cell or source cell,

[0377] The terminal device performs the Packet Data Convergence Protocol (PDCP) entity reconstruction, Medium Access Control (MAC) reconstruction and Radio Link Control (RLC) reconstruction.

[0378] In some embodiments, the terminal device performs the first process according to the instruction information, including:

[0379] If the terminal device is not configured with Inter-CU LTM or is not instructed to use Inter-CU LTM, or the gNB ID of the target cell or candidate cell is the same as the gNB ID of the serving cell or source cell,

[0380] The terminal device:

[0381] Performing a Medium Access Control (MAC) re-establishment; or

[0382] Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or

[0383] When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, media access control (MAC) reconstruction is performed; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery are performed.

[0384] In some embodiments, the indication information further includes: indication information per radio bearer (RB) and / or per radio link control (RLC) entity.

[0385] In some embodiments, the indication information per radio link control (RLC) entity includes an indication of radio link control (RLC) entity reestablishment, and if radio link control (RLC) entity reestablishment is indicated or configured in the radio link control (RLC) configuration associated with the radio bearer (RB), the first processing includes radio link control (RLC) entity reestablishment; and / or

[0386] The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) data recovery, and if packet data convergence protocol (PDCP) data recovery is indicated or configured in the radio bearer (RB) configuration of the data radio bearer (DRB), the first processing includes packet data convergence protocol (PDCP) data recovery; and / or

[0387] The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) entity reconstruction. If entity reconstruction is indicated or configured in the radio bearer (RB) configuration of the data radio bearer (DRB) or the signaling radio bearer (SRB), the first processing includes packet data convergence protocol (PDCP) entity reconstruction.

[0388] In some embodiments, for the signaling radio bearer (SRB), the first processing further includes protocol data unit and / or signaling data unit (PDU and / or SDU) discarding.

[0389] In some embodiments, the data radio bearer (DRB) is a data radio bearer (DRB) of at least part of a current terminal equipment (UE) configuration of a cell group triggered by the layer 1 / layer 2 triggered mobility (LTM) cell change procedure; and / or

[0390] The signaling radio bearer (SRB) is part or all of the signaling radio bearers (SRBs) configured for the terminal device.

[0391] In some embodiments, the data radio bearer (DRB) includes an acknowledged mode data radio bearer (AM DRB) and / or an unacknowledged mode data radio bearer (UM DRB);

[0392] The signaling radio bearer (SRB) includes signaling radio bearer 1 (SRB1) and / or signaling radio bearer 2 (SRB2) and / or signaling radio bearer 3 (SRB3).

[0393] Embodiments of the fifth aspect

[0394] An embodiment of the fifth aspect of the present application provides a communication system, which may include a network device and a terminal device.

[0395] Figure 9 is a schematic diagram of an electronic device according to an embodiment of the fifth aspect. As shown in Figure 9 , electronic device 900 may correspond to terminal device 102 or network device 101 in Figure 1 . Electronic device 900 may include a processor 910 and a memory 920 ; the memory 920 stores data and programs and is coupled to processor 910 . It should be noted that this diagram is exemplary; other types of structures may be used to supplement or replace this structure to implement telecommunication functions or other functions.

[0396] For example, the processor 910 may be configured to execute a program to implement the method in the first embodiment and / or the method in the second embodiment.

[0397] As shown in Figure 9 , the terminal device 900 may further include: a communication module 930, an input unit 940, a display 950, and a power supply 960. The functions of these components are similar to those in the prior art and are not described in detail here. It is worth noting that the terminal device 900 does not necessarily include all of the components shown in Figure 9 , and these components are not essential. Furthermore, the terminal device 900 may also include components not shown in Figure 9 , for which reference may be made to the prior art.

[0398] An embodiment of the present application also provides a computer program, wherein when the program is executed in a terminal device, the program causes the terminal device to execute the method in the embodiment of the first aspect.

[0399] An embodiment of the present application also provides a storage medium storing a computer program, wherein the computer program enables a terminal device to execute the method in the embodiment of the first aspect.

[0400] An embodiment of the present application also provides a computer program, wherein when the program is executed in a network device, the program causes the network device to execute the method in the embodiment of the second aspect.

[0401] An embodiment of the present application also provides a storage medium storing a computer program, wherein the computer program enables a network device to execute the method in the embodiment of the second aspect.

[0402] The above devices and methods of the present application can be implemented by hardware or by a combination of hardware and software. The present application relates to such a computer-readable program that, when executed by a logic component, enables the logic component to implement the devices or components described above, or enables the logic component to implement the various methods or steps described above. The present application also relates to a storage medium for storing the above program, such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, etc.

[0403] The method / device described in conjunction with the embodiments of the present application can be directly embodied as hardware, a software module executed by a processor, or a combination of the two. For example, one or more of the functional block diagrams shown in the figure and / or one or more combinations of functional block diagrams can correspond to various software modules of the computer program flow or to various hardware modules. These software modules can respectively correspond to the various steps shown in the figure. These hardware modules can be implemented by solidifying these software modules, for example, using a field programmable gate array (FPGA).

[0404] The software module may be located in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. A storage medium may be coupled to a processor so that the processor can read information from the storage medium and write information to the storage medium; or the storage medium may be an integral part of the processor. The processor and the storage medium may be located in an ASIC. The software module may be stored in the memory of the mobile terminal or in a memory card that can be inserted into the mobile terminal. For example, if the device (such as a mobile terminal) uses a large-capacity MEGA-SIM card or a large-capacity flash memory device, the software module may be stored in the MEGA-SIM card or the large-capacity flash memory device.

[0405] One or more of the functional blocks and / or one or more combinations of functional blocks described in the accompanying drawings may be implemented as a 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, a discrete gate or transistor logic device, a discrete hardware component, or any appropriate combination thereof for performing the functions described in this application. One or more of the functional blocks and / or one or more combinations of functional blocks described in the accompanying drawings may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in communication with a DSP, or any other such configuration.

[0406] The present application has been described above in conjunction with specific embodiments. However, those skilled in the art should understand that these descriptions are merely illustrative and are not intended to limit the scope of protection of the present application. Those skilled in the art may make various modifications and variations to the present application based on the spirit and principles of the present application, and such modifications and variations are also within the scope of the present application.

[0407] Regarding the implementation methods including the above embodiments, the following additional notes are also disclosed:

[0408] 1. A communication method, applied to a network device, characterized in that the method comprises:

[0409] The network device sends instruction information to the terminal device,

[0410] Among them, for the layer 1 / layer 2 triggered mobility (LTM) cell change process, the terminal device performs a first processing according to the indication information, and the first processing includes at least packet data convergence protocol (PDCP) data recovery and / or packet data convergence protocol (PDCP) entity reconstruction.

[0411] 2. The method as described in Note 1, wherein:

[0412] The indication information includes at least one of the following information:

[0413] Safety-related information;

[0414] Inter-CU LTM information;

[0415] A first identifier (ID) indicating layer 2 (L2) behavior.

[0416] 3. The method as described in Note 2, wherein:

[0417] The security-related information includes at least one of the following information:

[0418] An indication of whether it is a safe update;

[0419] An indication of whether security keys have changed, the security keys including primary keys and / or secondary keys.

[0420] 4. The method as described in Note 2, wherein:

[0421] The Inter-CU LTM information is used to indicate Inter-CU LTM, and is included in at least one of the following information:

[0422] Reference configuration;

[0423] Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configurations;

[0424] Radio Resource Control (RRC) reconfiguration message outside of Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configuration.

[0425] 5. The method as described in Note 2, wherein:

[0426] The Inter-CU LTM information includes:

[0427] The length of the cell identifier (ID) and the network equipment identifier (gNB ID).

[0428] 6. The method as described in Note 2, wherein:

[0429] The first identification (ID) is different from the second identification (ID); or

[0430] The value of the first identifier (ID) is an extended value of the second identifier (ID),

[0431] The second identifier is a no-reset identifier (ID).

[0432] 7. The method as described in Note 1, wherein:

[0433] The indication information is included in a radio resource control (RRC) message or a medium access control element (MAC CE), wherein:

[0434] The radio resource control (RRC) message includes a radio resource control (RRC) reconfiguration message for configuring layer 1 / layer 2 triggered mobility (LTM) candidate configuration or serving cell configuration; and / or

[0435] The media access control control element (MAC CE) is a layer 1 / layer 2 triggered mobility (LTM) cell change command media access control control element (MAC CE), or a media access control control element (MAC CE) for security or inter-central unit (inter-CU) LTM or layer 2 (L2) processing.

[0436] 8. The method as described in Note 2, wherein:

[0437] The indication information further includes: indication information of each radio bearer (RB) and / or each radio link control (RLC) entity.

[0438] 9. The method as described in Supplementary Note 8, wherein:

[0439] The indication information of each radio link control (RLC) entity includes an indication of radio link control (RLC) entity reestablishment, and if radio link control (RLC) entity reestablishment is indicated or configured in the radio link control (RLC) configuration associated with the radio bearer (RB), the first processing includes radio link control (RLC) entity reestablishment; and / or

[0440] The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) data recovery, and if packet data convergence protocol (PDCP) data recovery is indicated or configured in the radio bearer (RB) configuration of the data radio bearer (DRB), the first processing includes packet data convergence protocol (PDCP) data recovery; and / or

[0441] The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) entity reconstruction. If entity reconstruction is indicated or configured in the radio bearer (RB) configuration of the data radio bearer (DRB) or the signaling radio bearer (SRB), the first processing includes packet data convergence protocol (PDCP) entity reconstruction.

[0442] 10. The method as described in Supplement 1, wherein:

[0443] The first processing is performed by the terminal device on a data radio bearer (DRB) and / or a signaling radio bearer (SRB),

[0444] The data radio bearer (DRB) includes an acknowledged mode data radio bearer (AM DRB) and / or an unacknowledged mode data radio bearer (UM DRB);

[0445] The signaling radio bearer (SRB) includes signaling radio bearer 1 (SRB1) and / or signaling radio bearer 2 (SRB2) and / or signaling radio bearer 3 (SRB3).

Claims

1. A communication device, applied to a terminal device, characterized in that: The apparatus includes a first processing unit, which causes the terminal device to perform the following operations: receiving instruction information sent by the network device; and For the layer 1 / layer 2 triggered mobility (LTM) cell change process, the terminal device performs a first process according to the indication information, and the first process includes at least packet data convergence protocol (PDCP) data recovery and / or packet data convergence protocol (PDCP) entity reconstruction.

2. The device according to claim 1, wherein The first processing is performed by the terminal device on a data radio bearer (DRB) and / or a signaling radio bearer (SRB).

3. The device according to claim 1, wherein The Layer 1 / Layer 2 Triggered Mobility (LTM) cell change procedure is triggered by one of the following methods: The Layer 1 / Layer 2 Triggered Mobility (LTM) Cell Change Command Media Access Control Element (MAC CE) is received by the lower layers; Triggered by a Layer 1 / Layer 2 triggered mobility (LTM) candidate cell selected in cell selection after handover failure or radio link failure; The terminal device is triggered when it determines that a trigger condition or an execution condition is met.

4. The device according to claim 1, wherein After applying the configuration of the target cell, the candidate cell, or the selected cell, the first processing is performed.

5. The device according to claim 1, wherein The indication information includes at least one of the following information: Safety-related information; Inter-CU LTM information; A first identifier (ID) indicating layer 2 (L2) behavior.

6. The device according to claim 5, wherein The security-related information includes at least one of the following information: An indication of whether it is a safe update; An indication of whether security keys have changed, the security keys including primary keys and / or secondary keys.

7. The device according to claim 5, wherein The Inter-CU LTM information is used to indicate Inter-CU LTM, and is included in at least one of the following information: Reference configuration; Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configurations; Radio Resource Control (RRC) reconfiguration message outside of Layer 1 / Layer 2 Triggered Mobility (LTM) candidate configuration.

8. The device according to claim 5, wherein The Inter-CU LTM information includes: The length of the cell identifier (ID) and the network equipment identifier (gNB ID).

9. The device according to claim 5, wherein The first identification (ID) is different from the second identification (ID); or The value of the first identifier (ID) is an extended value of the second identifier (ID), The second identifier is a no-reset identifier (ID).

10. The device of claim 1, wherein: The indication information is included in a radio resource control (RRC) message or a medium access control element (MAC CE).

11. The device according to claim 1, wherein The terminal device performs the first process according to the instruction information, including: If the first identifier (ID) of the target cell or the candidate cell is the same as the first identifier (ID) of the serving cell or the source cell, the terminal device: Performing a Medium Access Control (MAC) re-establishment; or Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or When the second identifier (ID) of the target cell or candidate cell is the same as the second identifier (ID) of the serving cell or source cell, perform media access control (MAC) reestablishment; when the second identifier (ID) of the target cell or candidate cell is different from the second identifier (ID) of the serving cell or source cell, perform media access control (MAC) reestablishment, Radio Link Control (RLC) re-establishment and Packet Data Convergence Protocol (PDCP) data recovery.

12. The device of claim 1, wherein The terminal device performs the first process according to the instruction information, including: If the first identifier (ID) of the target cell or candidate cell is different from the first identifier (ID) of the serving cell or source cell, the terminal device performs the packet data convergence protocol (PDCP) entity reconstruction, media access control (MAC) reconstruction and radio link control (RLC) reconstruction.

13. The device of claim 1, wherein: The terminal device performs the first process according to the instruction information, including: If the terminal device is configured with a security update indication or is instructed to perform a security update, or is configured with a security key change indication or is instructed to perform a security key change, The terminal device performs the Packet Data Convergence Protocol (PDCP) entity reconstruction, Medium Access Control (MAC) reconstruction and Radio Link Control (RLC) reconstruction.

14. The device of claim 1, wherein: The terminal device performs the first process according to the instruction information, including: If the terminal device is not configured with a security update instruction or is instructed not to update security, or is not configured with a security key change instruction or is instructed not to change security keys, The terminal device: Performing a Medium Access Control (MAC) re-establishment; or Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, perform media access control (MAC) reconstruction; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, perform media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery.

15. The apparatus of claim 1, wherein: The terminal device performs the first process according to the instruction information, including: If the terminal device is configured with Inter-CU LTM or is instructed to use Inter-CU LTM, or the target cell or candidate cell The gNB ID of the selected cell is different from the gNB ID of the serving cell or source cell. The terminal device performs the Packet Data Convergence Protocol (PDCP) entity reconstruction, Medium Access Control (MAC) reconstruction and Radio Link Control (RLC) reconstruction.

16. The apparatus of claim 1, wherein: The terminal device performs the first process according to the instruction information, including: If the terminal device is not configured with Inter-CU LTM or is not instructed to use Inter-CU LTM, or the gNB ID of the target cell or candidate cell is the same as the gNB ID of the serving cell or source cell, The terminal device: Performing a Medium Access Control (MAC) re-establishment; or Performing Medium Access Control (MAC) re-establishment, Radio Link Control (RLC) re-establishment, and Packet Data Convergence Protocol (PDCP) data recovery; or When the second ID of the target cell or candidate cell is the same as the second ID of the serving cell or source cell, media access control (MAC) reconstruction is performed; when the second ID of the target cell or candidate cell is different from the second ID of the serving cell or source cell, media access control (MAC) reconstruction, radio link control (RLC) reconstruction and packet data convergence protocol (PDCP) data recovery are performed.

17. The apparatus of claim 5, wherein: The indication information further includes: indication information of each radio bearer (RB) and / or each radio link control (RLC) entity.

18. The apparatus of claim 17, wherein: The indication information of each radio link control (RLC) entity includes an indication of radio link control (RLC) entity reestablishment, and if radio link control (RLC) entity reestablishment is indicated or configured in the radio link control (RLC) configuration associated with the radio bearer (RB), the first processing includes radio link control (RLC) entity reestablishment; and / or The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) data recovery. If the radio bearer (RB) configuration of the data radio bearer (DRB) indicates or configures a packet Data Convergence Protocol (PDCP) data recovery, the first processing includes packet data convergence protocol (PDCP) data recovery; and / or The indication information of each radio bearer (RB) includes an indication of packet data convergence protocol (PDCP) entity reconstruction. If entity reconstruction is indicated or configured in the radio bearer (RB) configuration of the data radio bearer (DRB) or the signaling radio bearer (SRB), the first processing includes packet data convergence protocol (PDCP) entity reconstruction.

19. The apparatus of claim 2, wherein: For the signaling radio bearer (SRB), the first processing further includes discarding a protocol data unit and / or a signaling data unit (PDU and / or SDU).

20. The apparatus of claim 2, wherein: The data radio bearer (DRB) is a data radio bearer (DRB) of at least part of the current terminal equipment (UE) configuration of the cell group triggered by the layer 1 / layer 2 triggered mobility (LTM) cell change procedure; and / or The signaling radio bearer (SRB) is part or all of the signaling radio bearers (SRBs) configured for the terminal device.

Images