Communication method, device, equipment, storage medium, chip, product and program

Abstract

The embodiment of the invention provides a communication method and device, equipment, a storage medium, a chip, a product and a program. The method comprises the steps that terminal equipment determines a target cell or first information; wherein the first information is used for indicating a target cell; and the terminal equipment accesses the target cell through a random access process, or the terminal equipment triggers a connection reestablishment process, or the terminal equipment determines a first candidate cell and executes switching to the first candidate cell.

Description

Communication method, device, equipment, storage medium, chip, product and program Technical Field

[0001] The embodiments of the present application relate to the field of mobile communication technologies, and specifically to a communication method, apparatus, device, storage medium, chip, product, and program. Background Art

[0002] The terminal device can switch from the source cell to the target cell through the switching process. However, if the terminal device fails to switch, the terminal device may not be able to establish a connection with the target cell, resulting in the terminal being unable to communicate with the target cell, thereby reducing the reliability of information transmission.

[0003] Summary of the Invention

[0004] Embodiments of the present application provide a communication method, apparatus, device, storage medium, chip, product, and program.

[0005] In a first aspect, an embodiment of the present application provides a communication method, the method comprising:

[0006] The terminal device determines a target cell or first information; wherein the first information is used to indicate the target cell;

[0007] The terminal device accesses the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0008] In a second aspect, an embodiment of the present application provides a communication method, the method comprising:

[0009] The source network device sends an identifier or first information of a target cell to the terminal device; wherein the first information is used to indicate the target cell;

[0010] The identifier of the target cell or the first information is used by the terminal device to access the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0011] In a third aspect, an embodiment of the present application provides a communication device, including:

[0012] a determining unit, configured to: determine a target cell or first information; wherein the first information is used to indicate the target cell;

[0013] The communication unit is used to: access the target cell through a random access process, or trigger a connection re-establishment process, or perform switching to the first candidate cell determined by the terminal device.

[0014] In a fourth aspect, an embodiment of the present application provides a communication device, including:

[0015] A communication unit, configured to: send an identifier of a target cell or first information to a terminal device; wherein the first information is used to indicate the target cell;

[0016] The identifier of the target cell or the first information is used by the terminal device to access the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0017] In a fifth aspect, an embodiment of the present application provides a communication device, including: a processor and a memory,

[0018] The memory stores a computer program executable on the processor.

[0019] When the processor executes the program, the method of the first aspect or the second aspect is implemented.

[0020] In a sixth aspect, an embodiment of the present application provides a computer storage medium, which stores one or more programs, and the one or more programs can be executed by one or more processors to implement the method described in the first aspect or the second aspect.

[0021] In a seventh aspect, an embodiment of the present application provides a chip, comprising: a processor, configured to call and run a computer program from a memory to implement the method described in the first aspect or the second aspect.

[0022] In an eighth aspect, an embodiment of the present application provides a computer program product, comprising a computer storage medium, wherein the computer storage medium stores a computer program, wherein the computer program comprises instructions that can be executed by at least one processor, and when the instructions are executed by the at least one processor, the method described in the first aspect or the second aspect is implemented.

[0023] In a ninth aspect, an embodiment of the present application provides a computer program, which enables a computer to execute the method described in the first aspect or the second aspect.

[0024] In an embodiment of the present application, a terminal device determines a target cell or first information; wherein the first information is used to indicate the target cell; the terminal device accesses the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs a handover to the first candidate cell. In this way, the terminal device can access the target cell through the random access process, or can access the target cell through the connection re-establishment process, or can access the first candidate cell, thereby enabling the terminal device to communicate in the target cell or the first candidate cell, thereby improving the reliability of information transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0026] FIG1 is a schematic diagram of an application scenario of an embodiment of the present application;

[0027] FIG2 is a schematic diagram of a switching process provided in an embodiment of the present application;

[0028] FIG3 is a flow chart of a communication method provided in an embodiment of the present application;

[0029] FIG4 is a flow chart of another communication method provided in an embodiment of the present application;

[0030] FIG5 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application;

[0031] FIG6 is a schematic diagram of the structure of another communication device provided in an embodiment of the present application;

[0032] FIG7 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0033] FIG8 is a schematic structural diagram of a chip according to an embodiment of the present application. DETAILED DESCRIPTION

[0034] The following will describe the technical solutions in the embodiments of this application in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0035] The technical solutions described in the embodiments of the present application can be combined arbitrarily without conflict. In the description of the present application, "multiple" means two or more, unless otherwise clearly defined.

[0036] Figure 1 is a schematic diagram of an application scenario of an embodiment of the present application. As shown in Figure 1, a communication system 100 may include a terminal device 110 and a network device 120. The network device 120 may communicate with the terminal device 110 via an air interface. The terminal device 110 and the network device 120 support multi-service transmission.

[0037] It should be understood that the embodiments of the present application are only exemplified by the communication system 100, but the embodiments of the present application are not limited thereto. That is to say, the technical solutions of the embodiments of the present application can be applied to various communication systems, such as: Global System of Mobile communication (GSM) system, Code Division Multiple Access (CDMA) system, Wideband Code Division Multiple Access (WCDMA) system, General Packet Radio Service (GPRS), Long Term Evolution (LTE) system, Advanced long term evolution (LTE-A) system, New Radio (NR) system, NR system evolution system, LTE on unlicensed spectrum (LTE-U) system, NR on unlicensed spectrum (NR-based access to unlicensed spectrum, NR-U) system, Universal Mobile Telecommunication System (UMTS), Wireless Local Area Networks (WLAN), Wireless Fidelity (WiFi), LTE Time Division Duplex (TDD), ... Wireless Fidelity (WiFi), Wireless Fidelity (WiFi), LTE Time Division Duplex (TDD), Universal Mobile Telecommunication System (UMTS), Wireless Local Area Networks (WLAN), Wireless Fidelity (WiFi), Wireless Fidelity (WiFi), Wireless Fidelity (WiFi), LTE Time Division Duplex (TDD), Universal Mobile Telecommunication System (UMTS), Wireless Fidelity (WiFi), Wireless System, UMTS), Internet of Things (IoT) system, Narrow Band Internet of Things (NB-IoT) system, enhanced Machine-Type Communications (eMTC) system, or future communication systems (such as 6G and 7G communication systems).

[0038] The network device 120 in the embodiment of the present application may include an access network device 121 and / or a core network device 122. The access network device may provide communication coverage for a specific geographical area and may communicate with a terminal device 110 (eg, UE) located within the coverage area.

[0039] The terminal in this application is a device with wireless communication capabilities, which can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; can also be deployed on the water (such as ships, etc.); can also be deployed in the air (for example, on airplanes, balloons, and satellites). The terminal device in this application can be called user equipment (UE), mobile station (MS), mobile terminal (MT), subscriber unit, subscriber station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device. The terminal device may include one of the following or a combination of at least two of the following: an Internet of Things device, a satellite terminal, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, a server, a mobile phone, a tablet computer (Pad), a computer with wireless transceiver capabilities, a handheld computer, a desktop computer, a personal digital assistant, a portable media player, a smart speaker, a navigation device, a smart watch, smart glasses, a smart necklace and other wearable devices, a pedometer, a digital TV, a Virtual Reality (VR) terminal device, an Augmented Reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical surgery, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a smart home, a wireless terminal in a smart city, a wireless terminal in a smart home, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home ... home, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal in a smart city, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal in a smart home, a wireless terminal The wireless terminals in the home and the vehicles, vehicle-mounted devices, vehicle-mounted modules, wireless modems, handheld devices, customer premises equipment (CPE), smart home appliances, etc. in the Internet of Vehicles system.

[0040] Optionally, the terminal device 110 may be any terminal device, including but not limited to a terminal device connected to the network device 120 or other terminal devices by wire or wireless connection.

[0041] Optionally, the terminal device 110 may be used for device-to-device (D2D) communication.

[0042] The access network device 121 may include one of the following or a combination of at least two: an evolved base station (eNB or eNodeB) in a Long Term Evolution (LTE) system, a next generation radio access network (NG RAN) device, a base station (gNB) in an NR system, a small station, a micro station, a wireless controller in a cloud radio access network (CRAN), a wireless fidelity (Wi-Fi) access point, a transmission reception point (TRP), a relay station, an access point, a vehicle-mounted device, a wearable device, a hub, a switch, a bridge, a router, a network device in a future evolved public land mobile network (PLMN), etc.

[0043] The core network device 122 can be a 5G core network (5G Core, 5GC) device. The core network device 122 can include one of the following or a combination of at least two: Access and Mobility Management Function (AMF), Authentication Server Function (AUSF), User Plane Function (UPF), Session Management Function (SMF), Location Management Function (LMF), Policy Control Function (PCF). In other embodiments, the core network device can also be an Evolved Packet Core (EPC) device of the LTE network, for example, a Session Management Function + Core Packet Gateway (SMF+PGW-C) device. It should be understood that SMF+PGW-C can simultaneously implement the functions that SMF and PGW-C can implement. During the network evolution process, the above-mentioned core network device 122 may also be called other names, or a new network entity may be formed by dividing the functions of the core network, which is not limited in this embodiment of the present application.

[0044] The functional units in the communication system 100 may also establish connections and implement communication via next generation (NG) network interfaces.

[0045] For example, the terminal device establishes an air interface connection with the access network device through the NR interface for transmitting user plane data and control plane signaling; the terminal device can establish a control plane signaling connection with the AMF through the NG interface 1 (referred to as N1); the access network device, such as the next generation wireless access base station (gNB), can establish a user plane data connection with the UPF through the NG interface 3 (referred to as N3); the access network device can establish a control plane signaling connection with the AMF through the NG interface 2 (referred to as N2); the UPF can establish a control plane signaling connection with the SMF through the NG interface 4 (referred to as N4); the UPF can exchange user plane data with the data network through the NG interface 6 (referred to as N6); the AMF can establish a control plane signaling connection with the SMF through the NG interface 11 (referred to as N11); the SMF can establish a control plane signaling connection with the PCF through the NG interface 7 (referred to as N7).

[0046] Figure 1 exemplarily shows a base station, a core network device and two terminal devices. Optionally, the wireless communication system 100 may include multiple base station devices and each base station may include other numbers of terminal devices within its coverage area, which is not limited in this embodiment of the present application.

[0047] It should be noted that Figure 1 is merely an example of a system applicable to this application. Of course, the methods described in the embodiments of this application can also be applied to other systems. Furthermore, the terms "system" and "network" are often used interchangeably herein. The term "and / or" herein simply describes an association relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " generally indicates that the associated objects are in an "or" relationship. It should also be understood that the "indication" mentioned in the embodiments of this application can be a direct indication, an indirect indication, or an indication of an association relationship. For example, "A indicates B" can mean that A directly indicates B, for example, B can obtain information through A; it can also mean that A indirectly indicates B, for example, A indicates C, and B can obtain information through C; or it can mean that A and B have an association relationship. It should also be understood that the "correspondence" mentioned in the embodiments of this application can mean that there is a direct or indirect correspondence between two objects, or that there is an association relationship between the two objects, or a relationship between an indicator and the indicated, a configuration and the configured, and so on. It should also be understood that the “predefined”, “protocol agreement”, “predetermined” or “predefined rules” mentioned in the embodiments of the present application can be implemented by pre-saving corresponding codes, tables or other methods that can be used to indicate relevant information in devices (for example, including terminal devices and network devices). This application does not limit its specific implementation method. For example, predefined can refer to what is defined in the protocol. It should also be understood that in the embodiments of the present application, the “protocol” may refer to a standard protocol in the field of communications, for example, it may include LTE protocols, NR protocols, and related protocols used in future communication systems, and this application does not limit this.

[0048] To facilitate understanding of the technical solutions of the embodiments of the present application, the relevant technologies of the embodiments of the present application are described below. The following relevant technologies can be arbitrarily combined with the technical solutions of the embodiments of the present application as optional solutions, and they all fall within the protection scope of the embodiments of the present application.

[0049] When a terminal device that is using network services moves from one cell to another, or due to reasons such as wireless transmission service load adjustment, activation operation maintenance, equipment failure, etc., in order to ensure communication continuity and service quality, the system must transfer the communication link between the terminal device and the source cell to the new target cell, that is, perform a switching process.

[0050] FIG2 is a schematic diagram of a switching process provided by an embodiment of the present application. As shown in FIG2 , taking the Xn interface switching process as an example, the entire switching process can be divided into the following three stages:

[0051] (1) Handover preparation: This includes measurement control and reporting, handover request, and confirmation. The handover confirmation message contains the handover command generated by the target cell. The source cell does not allow any modification to the handover command generated by the target cell and directly forwards the handover command to the terminal device.

[0052] (2) Handover execution: After receiving the handover command, the terminal device immediately executes the handover process, that is, the terminal device disconnects from the source cell and connects to the target cell (such as performing random access, sending a Radio Resource Control (RRC) handover completion message to the target base station, etc.); the sequence number (SN) state is transferred, and data is forwarded.

[0053] (3) Handover completion: The target base station performs path switching with the Access and Mobility Management Function (AMF) and User Port Function (UPF), releasing the terminal device context of the source base station.

[0054] In FIG2 , the handover process may include the following steps 1 to 12 .

[0055] Before step 1, the terminal device exchanges user data with the source base station, and the source base station exchanges user data with the UPF(s). Before step 1, there may also be step 0: providing mobility control information through the AMF.

[0056] In any embodiment of the present application, the source base station may be a base station corresponding to a source cell or a network device corresponding to the source cell, and the target base station may be a base station corresponding to a target cell or a network device corresponding to the target cell.

[0057] Step 1: Measurement control and reporting. The source base station configures measurements for the terminal device. The measurement results of the terminal device will be used to assist the source base station in making handover decisions. The terminal device then reports the measurements based on the measurement configuration.

[0058] Step 2: Handover determination: the source base station refers to the measurement report results of the terminal device and makes a handover decision based on its own handover algorithm.

[0059] Step 3: The source base station sends a handover request to the target base station. The source base station sends a handover request message to the target base station. This message contains relevant information for handover preparation, including the terminal device's X2 and S1 signaling context references, the target cell identifier, keys, RRC context, access stratum (AS) configuration, and Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Radio Access Bearer (E-RAB) context. It also contains the source cell's physical layer identifier and a message authentication code for use in the recovery process after a possible handover failure. The terminal device's X2 and S1 signaling context references help the target base station locate the source base station. The E-RAB context includes necessary Radio Network Layer (RLN) and Transport Network Layer (TNL), addressing information, and E-RAB Quality of Service (QoS) information. A portion of the handover preparation information is included in the interface message itself (eg, target cell identifier), and another portion exists in the RRC container of the interface message (eg, RRC context).

[0060] Step 4: Admission control: The target base station performs admission control based on the received E-RAB QoS information to improve the success rate of handover. Admission control should take into account the reservation of corresponding resources, the Cell Radio Network Temporary Identity (C-RNTI), and the allocation of dedicated random access preamble codes. The AS configuration used by the target cell can be a complete configuration completely independent of the source cell, or it can be an incremental configuration based on the source cell (incremental configuration means that the same parts are not configured, and only the different parts are reconfigured through signaling. The terminal device will continue to use the original configuration for the configuration it has not received).

[0061] Step 5: The target base station sends a handover request confirmation to the source base station, and the target base station prepares for the handover and sends an Acknowledgement (ACK) message of the handover request to the source base station. The message contains an RRC container, and the specific content is the handover command that triggers the terminal device to switch. The source base station handover command is sent to the terminal device in a transparent manner (without any modification). The handover command contains a new C-RNTI, the case algorithm identifier of the target base station, and may also carry a random access dedicated Preamble code, access parameters, system information, etc. If necessary, the handover request ACK message may also carry Radio Network Layer (RNL) / Transport Network Layer (TNL) information for data forwarding. When the source base station receives the handover request ACK message or forwards the handover command to the terminal device, data forwarding can begin.

[0062] Step 6: RAN Handover Initiation. In step 6, the source base station sends a handover command to the terminal device. The handover command (an RRC connection reconfiguration message carrying mobility control information) is generated by the target base station and transparently transmitted to the terminal device by the source base station. When the terminal device receives this message, it uses the relevant parameters in the message to initiate the handover process. The terminal device can initiate the handover process without waiting for the Hybrid Automatic Repeat reQuest (HARQ) / Automatic Repeat reQuest (ARQ) response sent by the lower layer to the source base station.

[0063] After step 6, the terminal device leaves the source base station and synchronizes to the target base station.

[0064] Step 7: The source base station transfers the SN to the target base station, which can also be SN status transmission. The source base station sends a sequence number (SN, Seq terminal equipment) status transfer message to the target base station, transmitting the uplink PDCP SN reception status and downlink PDCP SN transmission status of the E-RAB (only those E-RABs that need to retain the Packet Data Convergence Protocol (PDCP) state need to perform SN status forwarding, corresponding to the Radio Link Control (RLC) Acknowledged Mode (AM) mode).

[0065] After step 7, the source base station provides the buffered data and new data from the UPF. Then, the UPF can send the user data to be transmitted to the terminal device to the source base station first, and the source base station forwards the user data to the target base station. The target base station can buffer the user data from the source base station.

[0066] Step 8: RAN switching is completed. In step 8, after receiving the switching command, the terminal device performs synchronization with the target cell. If a random access dedicated preamble code is configured in the switching command, the non-contention random access process is used to access the target cell. If no dedicated preamble code is configured, the contention random access process is used to access the target cell.

[0067] After step 8, the terminal device will transmit user data with the UPF through the target base station.

[0068] Step 9: The target eNB sends a path switching request to the AMF. The target eNB informs the AMF that the terminal device has changed cells through the path switching request message. At this point, the air interface handover has been successfully completed.

[0069] Step 10: Path switching in UPF can be achieved through the following steps: AMF sends a user plane update request to UPF, UPF switches the downlink data path, and UPF sends a user plane update response to AMF.

[0070] In order to assist the rescheduling function at the target base station, the UPF sends one or more "End Marker Packets" on the old path immediately after the path switch. The "End Marker Packet" does not contain user data and is indicated by the GPRS Tunneling Protocol (GTP) header. After completing the sending of the packet containing the identifier, the UPF should not send any data packets on the old path. After receiving the "End Marker Packet", if forwarding is activated for this bearer, the source base station should send this packet to the target base station. After detecting the "End Marker Packet", the target base station should discard the "End Marker Packet" and initiate any necessary processes to maintain the in-order delivery of users so that user data is transmitted between the UPF and the target base station.

[0071] Step 11: AMF sends a path switching request confirmation to the target base station, completing the path switching process.

[0072] Step 12: The target base station sends a terminal device context release to the source base station. The source base station receives the terminal device context release sent by the target base station and releases the terminal device context.

[0073] In order to reduce the delay caused by switching, NR R18 supports switching based on layer 1 / layer 2 (L1 / L2). Switching based on L1 / L2 is mainly aimed at the intra-central unit (intra-CU) switching scenario, and switching is performed based on layer 1 or layer 2 signaling when the PDCP and / or key of the centralized unit (CU) remains unchanged.

[0074] LTE Release 14 introduces Random Access Channel-less (RACH-less) handover. The terminal device's Timing Advance (TA) is 0 or the same as the TA value of the source cell. After receiving the handover command, the terminal device can directly transmit uplink data to the target base station. For RACH-less handover, the terminal device determines handover completion based on the Media Access Control Element (MAC CE) receiving the terminal device's contention resolution identity from the target cell.

[0075] In any embodiment of the present application, time advance may also be referred to as time advance, timing advance, or timing advance. In any embodiment of the present application, RACH-less may be understood synonymously with RACH less.

[0076] For L1 / L2 handovers, reducing UE uplink synchronization latency is one of the key optimization areas for L1 / L2 mobility. One approach is to pre-acquire the UE's TA in the target cell. This means that when a handover is triggered, the UE does not need to perform the random access procedure again to acquire the TA. Instead, it interacts with the target cell based on the already acquired TA.

[0077] A potential problem with obtaining TA in advance is that when the UE actually performs the handover, the TA may no longer be valid due to the UE's movement, or the link quality corresponding to the beam indicated by the network in the handover hit cannot meet the transmission requirements. In this case, the UE can only try uplink transmission until T304 times out, and the handover is considered to have failed.

[0078] In order to avoid the RRC connection re-establishment caused by the above-mentioned handover failure, the present application provides a method for falling back to traditional random access, avoiding unnecessary reconstruction procedures.

[0079] To facilitate understanding of the technical solutions of the embodiments of the present application, the technical solutions of the present application are described in detail below through specific embodiments. The above related technologies can be combined arbitrarily with the technical solutions of the embodiments of the present application as optional solutions, and all of them fall within the scope of protection of the embodiments of the present application. The embodiments of the present application include at least part of the following contents.

[0080] FIG3 is a flow chart of a communication method provided in an embodiment of the present application. As shown in FIG3 , the method includes:

[0081] S301. The terminal device determines a target cell or first information; wherein the first information is used to indicate the target cell.

[0082] S302. The terminal device accesses the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0083] Optionally, the terminal device may determine the target cell or the first information based on the measurement result of at least one candidate cell. Optionally, the terminal device may measure at least one candidate cell to obtain the measurement result of the at least one candidate cell. Optionally, the measurement result of the at least one candidate cell may be included in a measurement report.

[0084] Optionally, the terminal device may receive the identifier or first information of the target cell sent by the (source) network device.

[0085] Optionally, the first information may include or indicate an identifier of the target cell. Optionally, the first information may also include or indicate information for accessing and / or switching to the target cell. Optionally, when the first information is sent by the (source) network device to the terminal device, the first information may be included in the handover command, or may be included in the reconfiguration message, or may be included in other signaling in the reconfiguration message.

[0086] Optionally, the terminal device accessing the target cell through a random access procedure may include the terminal device accessing the target cell through a random access procedure based on random access information of the target cell. Optionally, the random access information may include at least one of the following: a random access preamble, random access resources, and a TA value.

[0087] Optionally, in any embodiment of the present application, the TA value may include an uplink TA value or a downlink TA value.

[0088] Optionally, the random access information of the target cell may be determined by the terminal device, or may be determined by the network device and sent to the terminal device. Optionally, the random access information of the target cell may be included in the handover command, or may be included in the reconfiguration message, or may be included in other signaling in the reconfiguration message.

[0089] Optionally, the terminal device triggering the connection re-establishment process may include: the terminal device sending a connection re-establishment request to the specific network device. Optionally, in some embodiments, the terminal device may receive a connection re-establishment message sent by the specific network device, and the terminal device may send a connection re-establishment completion message to the specific network device. Optionally, in other embodiments, the terminal device may receive a connection re-establishment rejection message sent by the specific network device. Optionally, the cell corresponding to the specific network device may be any cell that the terminal device can search for. For example, the specific network device may include any one of the following network devices: a source network device corresponding to a source cell, a target network device corresponding to a target cell, a network device corresponding to a first candidate cell, a network device corresponding to at least one candidate cell, and a network device corresponding to a cell other than at least one candidate cell.

[0090] Optionally, the terminal device may determine the first candidate cell by itself and perform handover to the first candidate cell. Optionally, the terminal device may determine the first candidate cell based on a measurement result of at least one candidate cell. Optionally, the terminal device may determine the first candidate cell from at least one candidate cell.

[0091] Optionally, the first information or the handover command may include the first candidate cell. Optionally, the TA values ​​of at least two cells among the first candidate cell, the target cell, and the source cell may be the same or different.

[0092] Optionally, performing switching to the first candidate cell may include: obtaining a TA value of the first candidate cell, and performing switching to the first candidate cell according to the TA value of the first candidate cell, or may include: initiating a random access procedure to access the first candidate cell.

[0093] Optionally, the terminal device triggers the connection re-establishment process, or the terminal device determines the first candidate cell and performs switching to the first candidate cell, which may include: the terminal device triggers the connection re-establishment process, or determines the first candidate cell and performs switching to the first candidate cell based on at least one of the following: cell information of the target cell, access information of the target cell, and information for accessing / or switching to the target cell.

[0094] Optionally, when the terminal device determines that it cannot access the target cell, the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs a handover to the first candidate cell. Optionally, the terminal device determines that it cannot access the target cell, which may include: the terminal device determines that it cannot access the target cell based on information previously obtained or sent by the source network device for accessing / or handing over to the target cell.

[0095] Optionally, when the first candidate cell is determined, the terminal device may access the first candidate cell through the TA value of the first candidate cell.

[0096] Optionally, the terminal device may access the first candidate cell through a random access procedure when the first candidate cell is determined. Optionally, the terminal device accessing the first candidate cell through the random access procedure may include: the terminal device may access the first candidate cell through the random access procedure based on random access information of the first candidate cell. Optionally, the random access information may include at least one of the following: a random access preamble, random access resources, and a TA value.

[0097] Optionally, the random access information of the target cell and / or the random access information of the first candidate cell may be pre-configured by the terminal device, or may be configured / activated by the source network device to the terminal device, or may be agreed upon by the protocol. Exemplarily, the random access information of the target cell and / or the random access information of the first candidate cell may be included in the signaling / configuration indicating at least one candidate cell, or may be included in the handover command. Optionally, the random access resources of the target cell and / or the random access resources of the first candidate cell may be configured grant (CG) resources or dynamic grant (DG) resources.

[0098] Optionally, when the terminal device fails to access the target cell through the random access process, the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0099] Optionally, when the terminal device fails to trigger the connection re-establishment process, the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0100] Optionally, when the terminal device fails to access the target cell through the random access process, the terminal device triggers the connection re-establishment process. When the terminal device fails to trigger the connection re-establishment process, the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0101] In an embodiment of the present application, a terminal device determines a target cell or first information; wherein the first information is used to indicate the target cell; the terminal device accesses the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs a handover to the first candidate cell. In this way, the terminal device can access the target cell through the random access process, or can access any cell through the connection re-establishment process, or can access the first candidate cell, thereby enabling the terminal device to communicate in the target cell or the first candidate cell, thereby improving the reliability of information transmission.

[0102] In some embodiments, the terminal device accesses the target cell through a random access process, including: if the terminal device fails to access the target cell within a first time period, the terminal device accesses the target cell through a random access process.

[0103] Optionally, the terminal device accesses the target cell through a random access procedure, and the corresponding terminal device fails to access the target cell, which may include: the terminal device fails to access the target cell according to one or more access methods other than the random access procedure. Optionally, the one or more access methods other than the random access procedure may include at least one of the following: the terminal device directly accesses the target cell (which may correspond to RACH-less switching), and the terminal device accesses the target cell according to the obtained TA value of the target cell (which may correspond to L1 / L2 switching).

[0104] Optionally, in any embodiment of the present application, access may include the terminal device performing uplink transmission based on the acquired resources or monitoring the downlink message. For example, accessing the target cell may include: the terminal device sending an uplink message (such as the second information) to the target network device based on the acquired resources, or monitoring the downlink message (such as PDCCH or PDSCH) sent by the target network device. For another example, accessing a specific cell (i.e., the cell corresponding to the specific network device) / the first candidate cell may include: the terminal device sending an uplink message to the specific network device / the network device corresponding to the first candidate cell based on the acquired resources, or monitoring the downlink message sent by the network device corresponding to the specific network device / the first candidate cell.

[0105] Optionally, the first duration may be less than the duration of timer T304. Optionally, the start time of the first duration may be the same as the start time of timer T304. Optionally, the first duration may be determined based on pre-configured information of the terminal device, or may be configured by the network device to the terminal device, or may be agreed upon in a protocol. Optionally, the first duration may be configured by the source network device through RRC signaling.

[0106] Optionally, the first duration may be timer T304. Thus, when timer T304 times out, the terminal device may execute the step of accessing the target cell through a random access procedure.

[0107] In some embodiments, the random access procedure includes a four-step random access procedure or a two-step random access procedure.

[0108] In some embodiments, the terminal device fails to access the target cell, which includes: after the terminal device sends second information to the target network device, the terminal device fails to receive third information sent by the target network device.

[0109] Optionally, the terminal device may send the second information via the uplink resources when there are available uplink resources. Optionally, the available uplink resources may be pre-configured by the source network device for the terminal device, such as the indication of the uplink resources may be included in the signaling / configuration for indicating at least one candidate cell to the terminal device, or the available uplink resources may be directly indicated or activated (for example, activating pre-configured resources) by the source network device to the terminal device, such as the indication of the uplink resources may be included in the handover command, or the available uplink resources may be agreed upon by the protocol. Optionally, the uplink resources in any embodiment of the present application may be configured authorized CG resources or dynamically authorized DG resources.

[0110] In other embodiments, the terminal device fails to access the target cell, including: the terminal device fails to monitor a physical downlink control channel PDCCH or a physical downlink shared channel PDSCH sent by a target network device.

[0111] Optionally, the terminal device may receive the second information, PDCCH or PDSCH on a downlink resource. Optionally, the downlink resource may be pre-configured by the terminal device, or may be configured by the source network device to the terminal device, or may be agreed upon by a protocol.

[0112] Optionally, when there are no available uplink resources, the terminal device monitors the downlink control channel PDCCH or PDSCH of the target cell.

[0113] Optionally, the PDCCH is used to schedule or activate uplink resources and / or downlink resources.

[0114] In some embodiments, the second information includes at least one of the following:

[0115] Reconfiguration completion message, handover execution / completion media access control control element MAC CE, cell radio network temporary identity C-RNTI MAC CE, buffer status report BSR, data message, scheduling request SR.

[0116] In some embodiments, the third information includes at least one of the following: a contention resolution identifier MAC CE of the terminal device and downlink information.

[0117] Optionally, the downlink information in any embodiment of the present application may include at least one of the following: downlink data information, PDCCH, PDSCH, downlink control information (Downlink Control Information, DCI), and downlink MAC CE.

[0118] In some embodiments, the terminal device accesses the target cell through a random access procedure, including:

[0119] The terminal device sends Msg3 / MsgA to the target network device; wherein, when the authorized size of the transmitted Msg3 / MsgA payload is greater than or equal to the uplink media access control MAC protocol data unit PDU, the uplink MAC PDU is sent to the target network device via Msg3 / MsgA.

[0120] In some embodiments, the terminal device accesses the target cell through a random access procedure, including:

[0121] The terminal device sends Msg3 / MsgA to the target network device; wherein, when the authorized size of transmitting the Msg3 / MsgA payload is smaller than the uplink MAC PDU, the part or all of the MAC service data unit SDU and / or part or all of the MAC CE are determined from the uplink MAC PDU, and the part or all of the MAC SDU and / or part or all of the MAC CE are sent to the target network device via Msg3 / MsgA.

[0122] Optionally, at least one of the uplink MAC PDU, MAC SDU, and MAC CE may correspond to all or part of the second information.

[0123] In some embodiments, the method also includes: the terminal device determines the timing advance TA value of the target cell; the terminal device accesses the target cell through a random access process, including: the terminal device accesses the target cell through a random access process after a second time period starting from the determination of the TA value of the target cell.

[0124] Optionally, the terminal device determines the timing advance TA value of the target cell before, after, or simultaneously with the terminal device determining the target cell or the first information. Exemplarily, in some scenarios, the terminal device determines the timing advance TA value of the target cell before the terminal device determines the target cell or the first information.

[0125] Optionally, the terminal device may independently determine the TA value of the target cell, or the terminal device may receive the TA value of the target cell sent by the source network device. Optionally, the terminal device may first determine the TA value of the target cell, and then determine the target cell or the first information, thereby accessing the target cell based on the TA value of the target cell. Optionally, the terminal device may first determine the TA value of at least one candidate cell, where the at least one candidate cell includes the target cell, and then determine the target cell or the first information, thereby accessing the target cell based on the TA value of the target cell.

[0126] Optionally, the second duration may be determined based on pre-configured information of the terminal device, or may be configured by the network device to the terminal device, or may be agreed upon in a protocol. Optionally, the start time of the second duration may be the time when the TA value of the target cell is determined, or may be determined based on the time when the TA value of the target cell is determined. Optionally, the second duration may be configured by the source network device through RRC signaling.

[0127] Optionally, the second duration may be greater than a specific duration, where the specific duration may be the duration between the moment when the terminal device determines the TA value of the target cell and the moment when the terminal device determines the target cell or the first information.

[0128] In some embodiments, the terminal device accesses the target cell through a random access procedure after a second time period starting from the determination of the TA value of the target cell, including: within the second time period starting from the determination of the TA value of the target cell, if the terminal device fails to access the target cell according to the TA value of the target cell, the terminal device accesses the target cell through a random access procedure after the second time period.

[0129] In some embodiments, the terminal device determining the timing advance TA value of the target cell may include: the terminal device receiving the TA value of the target cell sent by a source network device.

[0130] Optionally, the TA value of the target cell may be included in the handover command, or may be included in the reconfiguration message, or may be included in other signaling in the reconfiguration message. Optionally, the source network device may determine the TA values ​​of the source network device and the terminal device, and obtain the TA difference between the source cell and the target cell, and determine the TA value of the target cell based on the TA values ​​of the source network device and the terminal device and the TA difference.

[0131] In some other embodiments, the terminal device determining the timing advance TA value of the target cell may include: the terminal device sending an uplink reference signal to a source network device, and receiving the TA value of the target cell sent by the source network device.

[0132] Optionally, the uplink reference signal may include at least one of the following: a sounding reference signal (SRS), a demodulation reference signal (DMRS), and a phase tracking reference signal (PTRS).

[0133] Optionally, the source network device may send uplink reference signal configuration information to the terminal device, and the terminal device may send an uplink reference signal to the source network device based on the uplink reference signal configuration information. Optionally, the source network device may determine a TA value between the source network device and the terminal device based on the uplink reference signal sent by the terminal device, and then the source network device may determine a TA value for the target cell based on the TA values ​​of the source network device and the terminal device and a TA difference. Optionally, the uplink reference signal configuration information may include resources used to send the uplink reference signal.

[0134] In some further embodiments, the terminal device determining the timing advance TA value of the target cell may include: the terminal device determining the TA value of the target cell according to a first measurement result of the target cell.

[0135] Optionally, the terminal device may receive at least one candidate cell sent by the source network device, so that the terminal device may measure the at least one candidate cell and obtain a measurement result of the at least one candidate cell. Since the at least one candidate cell includes the target cell, the terminal device may obtain a first measurement result of the target cell. Optionally, the measurement result of the at least one candidate cell may be included in a measurement report.

[0136] Optionally, the terminal device measures at least one candidate cell based on the configuration information to obtain a measurement result of the at least one candidate cell. The at least one candidate cell may include a source cell and a target cell. The terminal device may determine whether to switch to the target cell based on the measurement result of the at least one candidate cell. In this case, before determining the target cell to be switched to, the terminal device may obtain a first measurement result of the target cell, thereby determining the TA value of the target cell.

[0137] Optionally, in any embodiment of the present application, the measurement results may include at least one of the following: reference signal received power (RSRP), reference signal received quality (RSRQ), received signal strength indicator (RSSI), and signal to interference and noise ratio (SINR).

[0138] In some further embodiments, the terminal device determines the timing advance TA value of the target cell, which may include: the terminal device determines the TA value of the target cell based on the TA value of the source cell and the TA difference between the source cell and the target cell.

[0139] Optionally, the terminal device may receive a TA difference between the source cell and the target cell sent by the source network device. Optionally, the TA value of the source cell and / or the TA difference between the source cell and the target cell may be included in a handover command, or may be included in a reconfiguration message, or may be included in other signaling in the reconfiguration message.

[0140] In some further embodiments, the terminal device determining the timing advance (TA) value of the target cell may include: the terminal device determining the TA value of the target cell through a random access procedure. Thus, in one embodiment, before the terminal device determines the target cell or the first information, the terminal device may determine the TA value of the target cell through a random access procedure. If the terminal device fails to access the target cell based on the TA value of the target cell, the terminal device may determine a new TA value of the target cell through the random access procedure and access the target cell using the new TA value.

[0141] Optionally, a random access process may be triggered by a PDCCH order or a DCI to enable the terminal device to determine the TA value of the target cell. For example, the source network device may send a PDCCH order or DCI to the terminal device, and the terminal device may initiate a random access process based on the PDCCH order or DCI to obtain the TA value of the target cell.

[0142] In some embodiments, the method further comprises:

[0143] Before the terminal device determines the target cell or the first information, the terminal device determines a first measurement result of the target cell; wherein the time of determining the first measurement result of the target cell corresponds to the time of determining the TA value of the target cell;

[0144] When the terminal device receives a handover command sent by a source network device or the terminal device needs to perform handover, the terminal device determines a second measurement result of the target cell;

[0145] The terminal device accesses the target cell through a random access process, including:

[0146] When the absolute value of the difference between the first measurement result and the second measurement result is greater than a first threshold, the terminal device accesses the target cell through a random access procedure.

[0147] Optionally, the first measurement result of the target cell may be a measurement result of a measurement report. Optionally, the first measurement result of the target cell may be determined before the terminal device determines that it needs to be handed over to the target cell.

[0148] Optionally, the time for determining the first measurement result of the target cell may be the same as the time for determining the TA value of the target cell, or may be separated by one or more time units. Optionally, a time unit may include or consist of at least one of the following: one or more frames, one or more subframes, one or more time slots, or one or more symbols. Optionally, the time for determining the first measurement result of the target cell may be determined before, after, or simultaneously with the time for determining the TA value of the target cell.

[0149] When the terminal device receives a handover command sent by the source network device or the terminal device needs to perform a handover, the terminal device may determine that it needs to be handed over to the target cell.

[0150] In related technologies, when the terminal device receives a handover command sent by the source network device or when the terminal device needs to perform a handover, the terminal device can directly send a message to the target network device based on the TA value of the target cell. However, in an embodiment of the present application, when the terminal device receives a handover command sent by the source network device or when the terminal device needs to perform a handover, the terminal device re-determines the second measurement result of the target cell and determines the method for the terminal device to access the target cell based on the first measurement result and the second measurement result.

[0151] Exemplarily, when the absolute value of the difference between the first measurement result and the second measurement result is greater than a first threshold, the terminal device accesses the target cell through a random access procedure.

[0152] In an embodiment of the present application, since the absolute value of the difference between the first measurement result and the second measurement result is greater than the first threshold, the terminal device determines that the TA value of the target cell does not meet the access requirements. At this time, the terminal device can determine the new TA value of the target cell through a random access process, and access the target cell according to the new TA value of the target cell, thereby avoiding the situation where the target cell cannot be accessed through the TA value of the target cell, resulting in reduced transmission reliability.

[0153] Optionally, in any embodiment of the present application, the TA value of the target cell may be referred to as the old TA value of the target cell or the first TA value of the target cell, and the new TA value of the target cell may be referred to as the second TA value of the target cell.

[0154] In some embodiments, the method further comprises:

[0155] When the absolute value of the difference between the first measurement result and the second measurement result is less than or equal to the first threshold, the terminal device performs handover to the target cell.

[0156] In this way, when the absolute value of the difference between the first measurement result and the second measurement result is less than or equal to the first threshold, the terminal device can perform switching to the target cell according to the TA value of the target cell, or can access the target cell according to the TA value of the target cell.

[0157] Optionally, the first threshold may be determined according to pre-configuration information of the terminal device, or may be configured by the network device to the terminal device, or may be agreed upon by a protocol.

[0158] In an embodiment of the present application, since the absolute value of the difference between the first measurement result and the second measurement result is less than or equal to the first threshold, the terminal device determines that the TA value of the target cell meets the access requirements. At this time, switching can be performed to the target cell based on the TA value of the target cell.

[0159] In some embodiments, the terminal device accesses the target cell through a random access procedure, including:

[0160] When the terminal device determines that the measurement result of the beam information of the target cell is less than or equal to a second threshold, the terminal device accesses the target cell through a random access procedure; wherein, the beam information of the target cell is indicated by the first information.

[0161] In other embodiments, the terminal device accesses the target cell through a random access procedure, including: when the terminal device determines the beam information of the target cell and there is no beam information with a measurement result greater than a second threshold, the terminal device accesses the target cell through a random access procedure.

[0162] Optionally, the beam information may include a reference signal and / or resource information of the reference signal.

[0163] Optionally, in any embodiment of the present application, the beam information can be replaced by a reference signal or a downlink reference signal, that is, the beam information of the target cell can be replaced by the downlink reference signal of the target cell, or, in any embodiment of the present application, the beam information can correspond to a spatial domain filter, for example, the transmit beam can correspond to a spatial domain transmission filter, and the receive beam can correspond to a spatial domain receive filter.

[0164] Optionally, the downlink reference signal may include at least one of the following: a synchronization signal block (SSB) and a channel state information reference signal (CSI-RS). The SSB may also be referred to as a synchronization signal / physical broadcast channel block (SS / PBCH block).

[0165] Optionally, the beam information of the target cell can be determined based on pre-configuration information of the terminal device, or can be configured by the network device to the terminal device, or can be agreed upon by the protocol. Optionally, the beam information of the target cell can be included in the first information, or can be included in the handover command, or can be included in the reconfiguration message, or can be included in other signaling in the reconfiguration message.

[0166] Optionally, the second threshold may be determined according to pre-configuration information of the terminal device, or may be configured by the network device to the terminal device, or may be agreed upon by a protocol.

[0167] In this way, since the measurement result of the beam information of the target cell is less than or equal to the second threshold, or since there is no beam information in the beam information of the target cell whose measurement result is greater than the second threshold, the terminal device determines that the TA value of the target cell does not meet the access requirements. At this time, the terminal device can determine the new TA value of the target cell through a random access process and access the target cell according to the new TA value of the target cell.

[0168] In some embodiments, the method further includes: when the terminal device determines that the measurement result of the beam information of the target cell is greater than the second threshold, the terminal device performs switching to the target cell.

[0169] In some other embodiments, the method further includes: when the terminal device determines the beam information of the target cell and there is beam information with a measurement result greater than the second threshold, the terminal device performs switching to the target cell.

[0170] In this way, since the measurement result of the beam information of the target cell is greater than the second threshold, or since the beam information of the target cell contains beam information whose measurement result is greater than the second threshold, the terminal device determines that the TA value of the target cell meets the access requirements. At this time, switching can be performed to the target cell based on the TA value of the target cell.

[0171] In some embodiments, the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell, including: within a third time period, when the terminal device fails to access the target cell, the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0172] Optionally, the third duration can be determined based on pre-configured information of the terminal device, or can be configured by the network device to the terminal device, or can be agreed upon in a protocol. Optionally, the timer corresponding to the third duration can be timer T304. Optionally, the start time of the third duration can be the same as or different from the start time corresponding to the first time. Optionally, the third duration can be configured by the source network device through RRC signaling.

[0173] Optionally, the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell, and the corresponding terminal device fails to access the target cell, which may include: the terminal device fails to access the target cell according to one or more access methods other than the random access process, or may include: the terminal device fails to access the target cell according to the random access process, or may include: the terminal device fails to access the target cell according to one or more access methods other than the random access process and the random access process.

[0174] Optionally, when the terminal device triggers a connection re-establishment process, the terminal device may send a reason for the re-establishment process to the specific network device.

[0175] Optionally, the first candidate cell may be a candidate cell other than the target cell. Optionally, the first candidate cell may be the target cell or a cell other than the target cell.

[0176] Optionally, the terminal device may determine the TA value of the first candidate cell, and perform handover to the first candidate cell, or access the first candidate cell, according to the TA value of the first candidate cell.

[0177] Optionally, the terminal device may perform handover to the first candidate cell based on the TA value of the first candidate cell obtained before determining the first candidate cell. Optionally, the terminal device may perform handover to the first candidate cell based on a new TA value of the first candidate cell obtained after determining the first candidate cell (for example, a new TA value obtained through a random access process). Optionally, the terminal device may perform handover to the first candidate cell based on the TA value of the first candidate cell sent by the source network device; wherein the TA value of the first candidate cell sent by the source network device may be included in the handover command, or may be included in the reconfiguration message, or may be included in other signaling in the reconfiguration message.

[0178] Exemplarily, before the terminal device determines the first candidate cell, the terminal device determines a third measurement result of the first candidate cell, wherein the time of determining the third measurement result of the first candidate cell corresponds to the time of determining the TA value of the first candidate cell; when the terminal device receives a handover command sent by a source network device or when the terminal device needs to perform a handover, the terminal device determines a fourth measurement result of the first candidate cell; when the absolute value of the difference between the third measurement result and the fourth measurement result is greater than a first threshold, the terminal device accesses the first candidate cell through a random access procedure. When the absolute value of the difference between the third measurement result and the fourth measurement result is less than or equal to the first threshold, the terminal device performs a handover to the first candidate cell based on the TA value of the first candidate cell.

[0179] Exemplarily, when the terminal device determines that the measurement result of the beam information of the first candidate cell is less than or equal to a second threshold, the terminal device accesses the first candidate cell through a random access procedure; wherein the beam information of the first candidate cell is indicated by the first information; or, when the terminal device determines that there is no beam information with a measurement result greater than the second threshold in the beam information of the first candidate cell, the terminal device accesses the first candidate cell through a random access procedure.

[0180] Exemplarily, when the terminal device determines that the measurement result of the beam information of the first candidate cell is greater than the second threshold, the terminal device performs switching to the first candidate cell; or, when the terminal device determines that there is beam information with a measurement result greater than the second threshold in the beam information of the first candidate cell, the terminal device performs switching to the first candidate cell.

[0181] In some embodiments, the third duration is greater than the first duration corresponding to the terminal device accessing the target cell through a random access procedure.

[0182] In some embodiments, within a first time period, if the terminal device fails to access the target cell through the TA of the target cell or according to RACH-less, the terminal device can access the target cell through a random access procedure. Within a third time period, if the terminal device fails to access the target cell through the random access procedure, the terminal device triggers a connection re-establishment procedure, or determines a first candidate cell and performs a handover to the first candidate cell.

[0183] In some embodiments, the start time of the timer corresponding to the first duration and / or the third duration is determined according to the time when the terminal device determines to arrive at the target cell.

[0184] Optionally, the start time of the timer corresponding to the first duration and / or the third duration may be the moment when the terminal device determines to arrive at the target cell. Optionally, the start time of the timer corresponding to the first duration and / or the third duration may be separated from the moment when the terminal device determines to arrive at the target cell by one or more time units. Optionally, the start time of the timer corresponding to the first duration and / or the third duration may be before or after the moment when the terminal device determines to arrive at the target cell, or the start time of the timer corresponding to the first duration and / or the third duration may be the same as the moment when the terminal device determines to arrive at the target cell.

[0185] In some embodiments, the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell, including: when the terminal device determines that the measured value of the beam information of the target cell is less than a third threshold, triggering the connection re-establishment process, or determining the first candidate cell and performing switching to the first candidate cell.

[0186] Optionally, the third threshold may be determined according to pre-configuration information of the terminal device, or may be configured by the network device to the terminal device, or may be agreed upon by a protocol.

[0187] Optionally, performing handover to the first candidate cell may include sending data information or an access request to a network device corresponding to the first candidate cell, where the data information or the access request may carry an identifier of the source cell and / or an identifier of the target cell. In this way, the network device corresponding to the first candidate cell may receive the context of the terminal device from the source network device or the target network device based on the identifier of the source cell and / or the identifier of the target cell sent by the terminal device.

[0188] In some embodiments, determining the first candidate cell includes:

[0189] The first candidate cell is determined according to a measurement result of at least one candidate cell; wherein the at least one candidate cell is indicated by a source network device to the terminal device.

[0190] Optionally, the first candidate cell may be: the candidate cell corresponding to the highest measurement result among the measurement results of the at least one candidate cell. Optionally, the first candidate cell may be: the candidate cell corresponding to the highest measurement result among the measurement results of cells other than the target cell among the at least one candidate cell.

[0191] In some embodiments, the terminal device determines the target cell or the first information, including: the terminal device receives a handover command sent by a source network device, and the handover command carries the identifier of the target cell or the first information.

[0192] In other embodiments, the terminal device determines the target cell or the first information, including: the terminal device determines the target cell or the first information based on the measurement results of at least one candidate cell; wherein the at least one candidate cell is indicated by the source network device to the terminal device.

[0193] In some embodiments, the first information includes at least one of the following:

[0194] The index or identifier of the target cell;

[0195] The TA value of the target cell;

[0196] The TA difference between the source cell and the target cell;

[0197] beam information of the target cell;

[0198] Resource information configured by the target cell for the terminal device;

[0199] The C-RNTI of the target cell;

[0200] No random access channel RACH-less handover type indication;

[0201] L1 / L2 handover type indication.

[0202] Optionally, the TA difference between the source cell and the target cell may also be referred to as a TA adjustment value in other embodiments.

[0203] Optionally, the beam information may include at least one of the following: transmission configuration indication (TCI) state (TCI state), SSB index (SSB index), and CSI-RS index (CSI-RS index).

[0204] Optionally, the resource information configured by the target cell to the terminal device may include granted CG resources or DG resources.

[0205] Optionally, when the handover command received by the terminal device carries an L1 / L2 handover type indication, the terminal device performs L1 / L2 handover. Optionally, when the handover command received by the terminal device carries an RACH-less handover type indication, the terminal device performs RACH-less handover.

[0206] In some embodiments, the method further includes: storing / generating a first report when the terminal device successfully switches to the first candidate cell.

[0207] In some other embodiments, the method further includes: storing / generating a second report when the terminal device successfully performs random access to the target cell.

[0208] Optionally, the first report and / or the second report may include at least one of the following: a measurement result obtained by the terminal device on at least one candidate cell before determining the target cell, a measurement result obtained by the terminal device on at least one candidate cell after determining the target cell, a first measurement result of the target cell, a second measurement result of the target cell, beam information of the target cell, the target cell indicated in the switching command, the target cell determined by the terminal device based on the measurement report, the TA value of the target cell, the new TA value of the target cell, and an identifier of the first candidate cell.

[0209] In some embodiments, the method further comprises one of the following:

[0210] The terminal device sends the first report to the network device corresponding to the first candidate cell;

[0211] The terminal device sends the second report to the target network device;

[0212] The terminal device receives a first reporting request sent by a network device corresponding to the first candidate cell, and the terminal device sends the first report to the network device corresponding to the first candidate cell;

[0213] The terminal device receives a second reporting request sent by the target network device, and the terminal device sends the second report to the target network device;

[0214] The terminal device sends indication information for indicating that the first report is stored to the network device corresponding to the first candidate cell, the terminal device receives the first reporting request sent by the network device corresponding to the first candidate cell, and the terminal device sends the first report to the network device corresponding to the first candidate cell;

[0215] The terminal device sends indication information to the target network device to indicate that the second report is stored, the terminal device receives the second reporting request sent by the target network device, and the terminal device sends the second report to the target network device.

[0216] Optionally, each time the terminal device receives the first report or the second report, it may report the first report or the second report to the network device corresponding to the first candidate cell or the target network device.

[0217] Optionally, when the terminal device successfully accesses the first candidate cell, the network device corresponding to the first candidate cell may send a first reporting request to the terminal device, or the terminal device sends indication information to the network device corresponding to the first candidate cell to indicate that the first report is stored.

[0218] Optionally, when the terminal device successfully accesses the target cell, the target network device may send a second reporting request to the terminal device, or the terminal device may send indication information to the target network device to indicate that the second report is stored.

[0219] Optionally, when the network device corresponding to the first candidate cell receives the first report, the network device corresponding to the first candidate cell may train or optimize the internally stored AI model based on the first report. Optionally, when the target network device receives the second report, the target network device may train or optimize the internally stored AI model based on the second report.

[0220] In some embodiments, before the terminal device accesses the target cell through a random access procedure, or the terminal device triggers a connection re-establishment procedure, or the terminal device determines a first candidate cell and performs a handover to the first candidate cell, the method further includes:

[0221] The terminal device performs L1 / L2 handover to the target cell; or

[0222] The terminal device performs RACH less switching to the target cell.

[0223] Optionally, the terminal device performing L1 / L2 switching to the target cell may include: the terminal device performing L1 / L2 switching to the target cell according to the TA value of the target cell.

[0224] Optionally, the terminal device performs RACH less switching to the target cell, which may include: the terminal device performs RACH less switching to the target cell according to the TA value of the target cell being 0, or the terminal device performs RACH less switching to the target cell according to the TA value of the source cell.

[0225] FIG4 is a flow chart of another communication method provided in an embodiment of the present application. As shown in FIG4 , the method includes:

[0226] S401. A source network device sends an identifier or first information of a target cell to a terminal device; wherein the first information is used to indicate the target cell;

[0227] The identifier of the target cell or the first information is used by the terminal device to access the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0228] Optionally, the identifier or first information of the target cell may be included in the handover command, or may be included in the reconfiguration message, or may be included in other signaling in the reconfiguration message.

[0229] In some embodiments, the first information includes at least one of the following:

[0230] The index or identifier of the target cell;

[0231] The TA value of the target cell;

[0232] A TA difference between the source cell and the target cell;

[0233] beam information of the target cell;

[0234] Resource information configured by the target cell for the terminal device;

[0235] The C-RNTI of the target cell;

[0236] No random access channel RACH-less handover type indication;

[0237] L1 / L2 handover type indication.

[0238] In some embodiments, the UE determines the target cell and / or the first information, and initiates a handover procedure to the target cell based on the first information.

[0239] Optionally, the UE initiating a handover process to the target cell includes at least one of the following (a)-(d) (for network-triggered handover, this refers to an act of receiving a handover command):

[0240] (a) The UE sends a first uplink message (corresponding to the second information in the above embodiment) to the target network device. The first uplink message may include at least one of the following: a reconfiguration completion message, a handover execution / completion MAC CE, a C-RNTI MAC CE, a buffer status report BSR, data, a scheduling request SR, etc.

[0241] After sending the first uplink message, the UE monitors the second downlink message (corresponding to the third message in the above embodiment) sent by the target network device, where the second downlink message is used to respond to the first uplink message. Optionally, after receiving the second downlink message, the UE stops the first timer and / or the second timer.

[0242] The handover execution / completion MAC CE is used to respond to the configuration information of the target cell, that is, the UE uses the configuration information provided by the target cell.

[0243] (b) monitoring a downlink control channel (PDCCH) of the target cell, where the PDCCH is used to schedule uplink and downlink resources.

[0244] If the UE has no available uplink resources to send the first uplink message, this step is performed.

[0245] (c) Starting a first timer (a new timer, where the duration corresponding to the first timer is the first duration, or the first timer may be timer T304).

[0246] The first timer is used for the UE to fall back to the random access procedure in a timely manner to avoid handover failure due to invalid TA or unreasonable beam indication.

[0247] (d) Starting a second timer (the second timer may be timer T304, and the duration corresponding to the second timer is the third duration).

[0248] The second timer may be a timer in the related art, used to determine whether the handover has failed. The timer is started when the UE receives the handover command and stopped if the handover is successful. If the timer expires, the handover is considered to have failed and the link re-establishment process is triggered. Optionally, the first timer duration may be smaller than the second timer duration.

[0249] In some embodiments, the first timer expiration behavior includes at least one of the following (a)-(c):

[0250] (a) Initiate a 4-step random access procedure.

[0251] Optionally, if the second timer times out, the UE triggers connection re-establishment or executes (c).

[0252] Optionally, if there is no beam that meets the conditions, the UE triggers connection re-establishment or executes (c).

[0253] (b) Initiate a 2-step random access procedure.

[0254] Optionally, if the second timer times out, the UE triggers connection re-establishment or executes (c).

[0255] Optionally, if there is no beam that meets the conditions, the UE triggers connection re-establishment or executes (c).

[0256] (c) determining a first candidate cell from at least one candidate cell, performing a handover to the first candidate cell, and restarting a second timer. The at least one candidate cell is preconfigured for the UE by the network. Optionally, the timing for restarting the second timer may be determined based on the moment the first candidate cell is determined, or based on the moment the terminal device sends a message to the network device corresponding to the first candidate cell.

[0257] Optionally, if before initiating the random access procedure, the UE transmits the first uplink message through uplink resources pre-configured or dynamically scheduled by the network, and stores the MAC PDU of the first uplink message in the first buffer, the UE determines the transmission mode based on whether the grant size for transmitting Msg3 / MsgA matches the size of the first uplink message:

[0258] Optionally, if the grant size of the transmitted Msg3 / MsgA payload matches the MAC PDU of the first uplink message, the UE can obtain the MAC PDU of the first uplink message from the first buffer and transmit it through Msg3 / MsgA; specifically, the UE obtains the MAC PDU from the first buffer (HARQ buffer) and stores it in the Msg3 / A buffer.

[0259] Optionally, if the grant size of the transmitted Msg3 / MsgA payload does not match the MAC PDU of the first uplink message, the UE obtains the MAC PDU of the first uplink message from the first buffer and instructs the multiplexing and assembly entity to reassemble the first uplink message according to the grant size of the Msg3 / MsgA payload, and the newly assembled first uplink message includes all or part of the MAC SDU / MAC CE in the original first uplink message. Specifically, the Multiplexing and assembly entity is instructed to carry MAC subPDU(s) in the new transmission, and the MAC subPDU(s) includes the MAC SDU in the MAC PDU.

[0260] In some embodiments, before the UE determines the target cell, the UE determines the TA value of the target cell and simultaneously starts a third timer and or stores the current first RSRP, wherein the first RSRP is included in the first measurement result.

[0261] Optionally, the UE determines the TA value of the target cell by one of the following:

[0262] The UE receives the TA value of the target cell sent by the source network, such as the TA command MAC CE;

[0263] The UE determines the TA value of the target cell by itself, for example, by calculating it on the UE side.

[0264] Optionally, when the UE determines the TA value of the target cell, the UE may report information used to determine the TA value to the source network device / target network device. For example, the UE may determine the TA value through RSRP or downlink (DL) TA timing difference.

[0265] Optionally, a third timer may be used to maintain the validity of the TA value of the target cell. The UE starts / restarts the third timer when determining the TA value of the target cell. The TA value is considered valid during the operation of the third timer. If the third timer times out when the UE initiates handover to the target cell, the UE considers the TA value invalid and falls back to the RACH-based handover process (same as the first timer timeout behavior).

[0266] The UE can store the first RSRP when determining the target cell's TA to determine the validity of the target cell's TA value. When initiating a handover to the target cell, the UE determines the second RSRP. If the difference between the first RSRP and the second RSRP exceeds a preconfigured threshold (corresponding to the first threshold in the above embodiment), the TA value of the target cell is considered invalid. The UE falls back to the RACH-based handover process. The second RSRP is included in the second measurement result.

[0267] In some embodiments, before the first timer expires, the UE's behavior may include one of the following (a)-(b):

[0268] (a) Determine whether the beam indicated by the first information meets the first threshold (corresponding to the second threshold in the above embodiment). If not, the UE considers that the first timer has timed out, or, if not, the terminal device accesses the target cell through a random access process.

[0269] (b) Determine whether the target cell has a beam that meets the first threshold. If not, it is considered that the first timer has timed out. In other words, if not, the terminal device accesses the target cell through a random access process.

[0270] In some embodiments, the stop condition of the first timer may include:

[0271] The UE receives a first downlink message sent by the target network device. The first downlink message may be any message carried by the PDCCH or PDSCH. Optionally, the first downlink message may be a UE contention resolution identity MAC CE (MAC CE).

[0272] In some embodiments, the first information includes at least one of the following:

[0273] Serving cell index; wherein the serving cell index may also be referred to as the target cell index;

[0274] TA information of the target cell; the TA information of the target cell may include the TA value of the target cell, or the TA adjustment value of the target cell;

[0275] Beam information of the target cell; the beam information of the target cell may include at least one of the following: TCI state of the target cell, SSB index of the target cell, CSI-RS index of the target cell;

[0276] First resource or first resource identifier; the first resource may include a CG resource or a DG resource;

[0277] The C-RNTI of the target cell;

[0278] RACH-less handover type indication;

[0279] L1 / L2 handover type indication.

[0280] Among them, the first resource can be the resource information configured by the target cell to the terminal device in the above embodiment.

[0281] In some embodiments, the UE determines the target cell includes one of the following (a)-(b):

[0282] (a) Network-based (NW-based): The UE receives a handover command that indicates the target cell.

[0283] (b) UE-based: The UE determines the target cell based on conditions / measurement events;

[0284] In some embodiments, if the UE successfully switches to the first candidate cell, a first report is stored / generated.

[0285] In some embodiments, if the UE successfully initiates random access to the target cell, a second report is stored / generated.

[0286] In some embodiments, the UE reports to the network the first and / or second reports currently stored, and reports the first / second reports based on indication information on the network side.

[0287] In an embodiment of the present application, the terminal device may adopt a fallback random access method in advance to avoid connection re-establishment due to switching failure.

[0288] An embodiment of the present application provides a method for timer-based fallback random access, including a UE determining to perform RACH-less switching or L1 / L2 switching, or to perform a RACH-based switching process based on the validity of a first timer and / or a TA value.

[0289] The preferred embodiments of the present application are described in detail above in conjunction with the accompanying drawings. However, the present application is not limited to the specific details in the above embodiments. Within the technical concept of the present application, the technical solution of the present application can be subjected to a variety of simple modifications, and these simple modifications all fall within the scope of protection of the present application. For example, the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present application will no longer describe the various possible combinations separately. For another example, the various different embodiments of the present application can also be arbitrarily combined, as long as they do not violate the idea of ​​the present application, they should also be regarded as the contents disclosed in the present application. For another example, under the premise of no conflict, the various embodiments and / or the technical features in each embodiment described in the present application can be arbitrarily combined with the prior art, and the technical solution obtained after the combination should also fall within the scope of protection of the present application.

[0290] It should also be understood that in the various method embodiments of the present application, the sequence numbers of the above-mentioned processes do not imply a precedence in their execution order. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. Furthermore, in the embodiments of the present application, the terms "downlink," "uplink," and "sidelink" are used to indicate the direction of signal or data transmission. "Downlink" indicates a signal or data transmission direction of a first direction, from a site to a user equipment in a cell; "uplink" indicates a signal or data transmission direction of a second direction, from a user equipment in a cell to a site; and "sidelink" indicates a signal or data transmission direction of a third direction, from user equipment 1 to user equipment 2. For example, "downlink signal" indicates that the signal is transmitted in the first direction. Furthermore, in the embodiments of the present application, the term "and / or" merely describes an association relationship between associated objects, indicating that three possible relationships exist. Specifically, "A and / or B" can represent three situations: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " as used herein generally indicates that the associated objects are in an "or" relationship.

[0291] FIG5 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application. As shown in FIG5 , the communication device 500 can be applied in a terminal device, or can be a terminal device, wherein the communication device 500 includes:

[0292] The determining unit 501 is configured to determine a target cell or first information, wherein the first information is used to indicate the target cell;

[0293] The communication unit 502 is configured to: access the target cell through a random access procedure, or trigger a connection re-establishment procedure, or perform handover to a determined first candidate cell.

[0294] In some embodiments, the communication unit 502 is further configured to: if the target cell is not accessed within the first time period, access the target cell through a random access procedure.

[0295] In some embodiments, the random access procedure includes a four-step random access procedure or a two-step random access procedure.

[0296] In some embodiments, the communication unit 502 is further configured to: after sending second information to the target network device, not receive third information sent by the target network device.

[0297] In some embodiments, the communication unit 502 is further configured to: fail to monitor a physical downlink control channel PDCCH or a physical downlink shared channel PDSCH sent by the target network device.

[0298] In some embodiments, the second information includes at least one of the following:

[0299] Reconfiguration completion message, handover execution / completion media access control control element MAC CE, cell radio network temporary identity C-RNTI MAC CE, buffer status report BSR, data message, scheduling request SR.

[0300] In some embodiments, the third information includes at least one of the following: UE contention resolution identifier MAC CE, downlink information.

[0301] In some embodiments, the communication unit 502 is further used to: send Msg3 / MsgA to the target network device; wherein, when the authorized size of the transmitted Msg3 / MsgA payload is greater than or equal to the uplink media access control MAC protocol data unit PDU, the uplink MAC PDU is sent to the target network device via Msg3 / MsgA.

[0302] In some embodiments, the communication unit 502 is further used to: send Msg3 / MsgA to the target network device; wherein, when the authorized size of the transmitted Msg3 / MsgA payload is smaller than the uplink MAC PDU, determine the part or all of the MAC service data unit SDU and / or part or all of the MAC CE from the uplink MAC PDU, and send the part or all of the MAC SDU and / or part or all of the MAC CE to the target network device via Msg3 / MsgA.

[0303] In some embodiments, the determination unit 501 is further used to: determine the timing advance TA value of the target cell; the communication unit 502 is further used to: access the target cell through a random access process after a second time period starting from the determination of the TA value of the target cell.

[0304] In some embodiments, the communication unit 502 is further used to: within the second time period starting from determining the TA value of the target cell, if the target cell is not accessed according to the TA value of the target cell, access the target cell through a random access process after the second time period.

[0305] In some embodiments, the communication unit 502 is further configured to: receive the TA value of the target cell sent by the source network device.

[0306] In some embodiments, the communication unit 502 is further configured to: send an uplink reference signal to a source network device, and receive a TA value of the target cell sent by the source network device.

[0307] In some embodiments, the determining unit 501 is further configured to: determine a TA value of the target cell according to the first measurement result of the target cell.

[0308] In some embodiments, the determining unit 501 is further configured to determine the TA value of the target cell according to the TA value of the source cell and the TA difference between the source cell and the target cell.

[0309] In some embodiments, the determining unit 501 is further configured to: determine the TA value of the target cell through a random access procedure.

[0310] In some embodiments, the determining unit 501 is further configured to: determine a first measurement result of the target cell before determining the target cell or the first information; wherein the time of determining the first measurement result of the target cell corresponds to the time of determining the TA value of the target cell; and determine a second measurement result of the target cell upon receiving a handover command sent by a source network device or when handover needs to be performed;

[0311] The communication unit 502 is further configured to: access the target cell through a random access procedure if an absolute value of a difference between the first measurement result and the second measurement result is greater than a first threshold.

[0312] In some embodiments, the communication unit 502 is further configured to: perform handover to the target cell if an absolute value of a difference between the first measurement result and the second measurement result is less than or equal to the first threshold.

[0313] In some embodiments, the communication unit 502 is further used to: access the target cell through a random access procedure when it is determined that the measurement result of the beam information of the target cell is less than or equal to a second threshold; wherein the beam information of the target cell is indicated by the first information.

[0314] In some embodiments, the communication unit 502 is further configured to: when it is determined that there is no beam information with a measurement result greater than a second threshold in the beam information of the target cell, access the target cell through a random access procedure.

[0315] In some embodiments, the communication unit 502 is further configured to: perform handover to the target cell when it is determined that the measurement result of the beam information of the target cell is greater than the second threshold.

[0316] In some embodiments, the communication unit 502 is further configured to: when it is determined that, in the beam information of the target cell, there is beam information with a measurement result greater than the second threshold, perform handover to the target cell.

[0317] In some embodiments, the communication unit 502 is further configured to: trigger a connection re-establishment process if the target cell is not accessed within a third time period, or determine a first candidate cell and perform a handover to the first candidate cell.

[0318] In some embodiments, the third duration is greater than a first duration corresponding to when the communication device 500 accesses the target cell through a random access procedure.

[0319] In some embodiments, the start time of the timer corresponding to the first duration and / or the third duration is determined according to the time when the communication device 500 determines to locate the target cell.

[0320] In some embodiments, the communication unit 502 is further used to: trigger a connection re-establishment process when it is determined that the measured value of the beam information of the target cell is less than a third threshold, or determine a first candidate cell and perform a handover to the first candidate cell.

[0321] In some embodiments, the determining unit 501 is further configured to: determine the first candidate cell according to a measurement result of at least one candidate cell; wherein the at least one candidate cell is indicated by a source network device to the communication apparatus 500 .

[0322] In some embodiments, the communication unit 502 is further configured to: receive a handover command sent by a source network device, where the handover command carries the identifier of the target cell or the first information.

[0323] In some embodiments, the determination unit 501 is further configured to: determine the target cell or the first information based on a measurement result of at least one candidate cell; wherein the at least one candidate cell is indicated by a source network device to the communication apparatus 500 .

[0324] In some embodiments, the first information includes at least one of the following:

[0325] The index or identifier of the target cell;

[0326] The TA value of the target cell;

[0327] The TA difference between the source cell and the target cell;

[0328] beam information of the target cell;

[0329] Resource information configured by the target cell to the communication device 500;

[0330] The C-RNTI of the target cell;

[0331] No random access channel RACH-less handover type indication;

[0332] L1 / L2 handover type indication.

[0333] In some embodiments, the communication device 500 further includes: a storage unit, the storage unit being configured to: store / generate a first report when handover to the first candidate cell is successful; or store / generate a second report when random access to the target cell is successful.

[0334] In some embodiments, the communication unit 502 is further configured to:

[0335] Sending the first report to a network device corresponding to the first candidate cell;

[0336] Sending the second report to the target network device;

[0337] receiving a first reporting request sent by a network device corresponding to the first candidate cell, and sending the first report to the network device corresponding to the first candidate cell;

[0338] receiving a second reporting request sent by the target network device, and sending the second report to the target network device;

[0339] Sending, to the network device corresponding to the first candidate cell, indication information indicating that the first report is stored, receiving a first reporting request sent by the network device corresponding to the first candidate cell, and sending the first report to the network device corresponding to the first candidate cell;

[0340] Send indication information for indicating that the second report is stored to the target network device, receive a second reporting request sent by the target network device, and send the second report to the target network device.

[0341] In some embodiments, the communication unit 502 is further configured to: perform L1 / L2 handover to the target cell; or perform RACH less handover to the target cell.

[0342] FIG6 is a schematic diagram of the structure of another communication device provided in an embodiment of the present application. As shown in FIG6 , the communication device 600 can be applied in a source network device, or can be a source network device, wherein the communication device 600 includes:

[0343] The communication unit 601 is configured to send an identifier or first information of a target cell to a terminal device; wherein the first information is used to indicate the target cell;

[0344] The identifier of the target cell or the first information is used by the terminal device to access the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

[0345] In some embodiments, the communication device 600 further includes a determining unit 602 configured to determine an identifier or first information of a target cell.

[0346] In some embodiments, the first information includes at least one of the following:

[0347] The index or identifier of the target cell;

[0348] The TA value of the target cell;

[0349] A TA difference between the source cell and the target cell;

[0350] beam information of the target cell;

[0351] Resource information configured by the target cell for the terminal device;

[0352] The C-RNTI of the target cell;

[0353] No random access channel RACH-less handover type indication;

[0354] L1 / L2 handover type indication.

[0355] Those skilled in the art should understand that the relevant description of the above-mentioned communication device in the embodiment of the present application can be understood with reference to the relevant description of the communication method in the embodiment of the present application.

[0356] Figure 7 is a schematic structural diagram of a communication device provided in an embodiment of the present application. The communication device 700 may include one of the following: a terminal device or a source network device. The communication device 700 shown in Figure 7 may include a processor 710 and a memory 720. The memory 720 stores a computer program executable on the processor 710. When the processor 710 executes the program, it implements the communication method of any of the above embodiments.

[0357] Optionally, the memory 720 may be a separate device independent of the processor 710 , or may be integrated into the processor 710 .

[0358] In some embodiments, as shown in FIG7 , the communication device 700 may further include a transceiver 730 , and the processor 710 may control the transceiver 730 to communicate with other devices. Specifically, the transceiver 730 may send information or data to other devices, or receive information or data sent by other devices.

[0359] The transceiver 730 may include a transmitter and a receiver. The transceiver 730 may further include an antenna, and the number of antennas may be one or more.

[0360] In some embodiments, the communication device 700 may specifically be a terminal device or a source network device in an embodiment of the present application, and the communication device 700 may implement the corresponding processes implemented by the terminal device or the source network device in each method of the embodiment of the present application. For the sake of brevity, they will not be repeated here.

[0361] An embodiment of the present application further provides a computer storage medium, which stores one or more programs. The one or more programs can be executed by one or more processors to implement the communication method in any embodiment of the present application.

[0362] In some embodiments, the computer-readable storage medium can be applied to the terminal device or source network device in the embodiments of the present application, and the computer program enables the computer to execute the corresponding processes implemented by the terminal device or source network device in the various methods of the embodiments of the present application. For the sake of brevity, they will not be repeated here.

[0363] Figure 8 is a schematic structural diagram of a chip in an embodiment of the present application. The chip 800 shown in Figure 8 includes a processor 810. The processor 810 is used to call and run a computer program from a memory to implement the method in any embodiment of the present application.

[0364] In some embodiments, as shown in FIG8 , the chip 800 may further include a memory 820 , wherein the processor 810 may call and execute a computer program from the memory 820 to implement the method in the embodiment of the present application.

[0365] The memory 820 may be a separate device independent of the processor 810 , or may be integrated into the processor 810 .

[0366] In some embodiments, the chip 800 may further include an input interface 830. The processor 810 may control the input interface 830 to communicate with other devices or chips, and specifically, may obtain information or data sent by other devices or chips.

[0367] In some embodiments, the chip 800 may further include an output interface 840. The processor 810 may control the output interface 840 to communicate with other devices or chips, and specifically, may output information or data to other devices or chips.

[0368] In some embodiments, the chip can be applied to the terminal device or source network device in the embodiments of the present application, and the chip can implement the corresponding processes implemented by the terminal device or source network device in the various methods of the embodiments of the present application. For the sake of brevity, they will not be repeated here.

[0369] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0370] An embodiment of the present application also provides a computer program product, which includes a computer storage medium, the computer storage medium storing a computer program, and the computer program including instructions that can be executed by at least one processor. When the instructions are executed by the at least one processor, the communication method in any embodiment of the present application is implemented.

[0371] In some embodiments, the computer program product can be applied to the terminal device or source network device in the embodiments of the present application, and the computer program instructions enable the computer to execute the corresponding processes implemented by the terminal device or source network device in the various methods of the embodiments of the present application. For the sake of brevity, they will not be repeated here.

[0372] Optionally, the computer program product in the embodiments of the present application may also be referred to as a software product in other embodiments.

[0373] An embodiment of the present application further provides a computer program, which enables a computer to execute the communication method in any embodiment of the present application.

[0374] In some embodiments, the computer program can be applied to the terminal device or source network device in the embodiments of the present application. When the computer program runs on the computer, the computer executes the corresponding processes implemented by the terminal device or source network device in the various methods of the embodiments of the present application. For the sake of brevity, they will not be repeated here.

[0375] The processor, communication device, processor or chip of the embodiment of the present application may be an integrated circuit chip with signal processing capability. In the implementation process, each step of the above-mentioned method embodiment can be completed by the integrated logic circuit of the hardware in the processor or the instruction in the form of software. The above-mentioned processor, communication device or chip may include the integration of any one or more of the following: general-purpose processor, application-specific integrated circuit (ASIC), digital signal processor (DSP), digital signal processing device (DSPD), programmable logic device (PLD), field programmable gate array (FPGA), central processing unit (CPU), graphics processing unit (GPU), embedded neural network processor (neural-network processing units, NPU), controller, microcontroller, microprocessor, programmable logic device, discrete gate or transistor logic device, discrete hardware component. Each method, step and logic block diagram disclosed in the embodiment of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiments of this application can be directly implemented and executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium well-known in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, etc. The storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above method.

[0376] It is understood that the memory or computer storage medium in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct RAM bus random access memory (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0377] It should be understood that the above-mentioned memory or computer storage medium is exemplary but not restrictive. For example, the memory in the embodiments of the present application may also be static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct RAM RAM (DR RAM), etc. In other words, the memory in the embodiments of the present application is intended to include, but is not limited to, these and any other suitable types of memory.

[0378] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0379] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0380] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0381] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0382] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0383] In any embodiment of the present application, the time interval, time period, duration range, duration or time window, etc. may include all endpoint times, or may include part of the endpoint time (for example, including the left endpoint time but not the right endpoint time, or including the right endpoint time but not the left endpoint time), or may not include the endpoint time.

[0384] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0385] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A communication method, comprising: The terminal device determines a target cell or first information; wherein the first information is used to indicate the target cell; The terminal device accesses the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

2. The method according to claim 1, wherein the terminal device accesses the target cell through a random access procedure, comprising: In a case where the terminal device fails to access the target cell within the first time period, the terminal device accesses the target cell through a random access procedure.

3. The method according to claim 2, wherein the random access procedure comprises a four-step random access procedure or a two-step random access procedure.

4. The method according to claim 2 or 3, wherein the terminal device fails to access the target cell, comprising one of the following: After the terminal device sends the second information to the target network device, the terminal device does not receive the third information sent by the target network device; The terminal device does not monitor the physical downlink control channel PDCCH or the physical downlink shared channel PDSCH sent by the target network device.

5. The method according to claim 4, wherein the second information comprises at least one of the following: Reconfiguration completion message, handover execution / completion media access control control element MAC CE, cell radio network temporary identity C-RNTI MAC CE, buffer status report BSR, data message, scheduling request SR.

6. According to the method according to claim 4 or 5, the third information includes at least one of the following: a contention resolution identifier MAC CE of the terminal device and downlink information.

7. The method according to any one of claims 4 to 6, wherein the terminal device accesses the target cell through a random access procedure, comprising: The terminal device sends Msg3 / MsgA to the target network device; wherein, when the authorized size of the transmitted Msg3 / MsgA payload is greater than or equal to the uplink media access control MAC protocol data unit PDU, the uplink MAC PDU is sent to the target network device via Msg3 / MsgA.

8. The method according to any one of claims 4 to 6, wherein the terminal device accesses the target cell through a random access procedure, comprising: The terminal device sends Msg3 / MsgA to the target network device; wherein, when the authorized size of transmitting the Msg3 / MsgA payload is smaller than the uplink MAC PDU, the part or all of the MAC service data unit SDU and / or part or all of the MAC CE are determined from the uplink MAC PDU, and the part or all of the MAC SDU and / or part or all of the MAC CE are sent to the target network device via Msg3 / MsgA.

9. The method according to claim 1, further comprising: The terminal device determines a timing advance TA value of the target cell; The terminal device accesses the target cell through a random access process, including: The terminal device accesses the target cell through a random access process after the second time period starting from determining the TA value of the target cell.

10. The method according to claim 9, wherein the terminal device accesses the target cell through a random access procedure after the second duration from when the TA value of the target cell is determined, comprising: Within the second time period starting from the time the terminal device determines the TA value of the target cell, if the terminal device fails to access the target cell based on the TA value of the target cell, the terminal device accesses the target cell through a random access process after the second time period.

11. The method according to claim 9 or 10, wherein the terminal device determines the timing advance (TA) value of the target cell, comprising one of the following: The terminal device receives the TA value of the target cell sent by the source network device; The terminal device sends an uplink reference signal to the source network device, and receives the TA value of the target cell sent by the source network device; Determining, by the terminal device, a TA value of the target cell according to the first measurement result of the target cell; The terminal device determines the TA value of the target cell according to the TA value of the source cell and the TA difference between the source cell and the target cell; The terminal device determines the TA value of the target cell through a random access process.

12. The method according to claim 1, further comprising: Before the terminal device determines the target cell or the first information, the terminal device determines a first measurement result of the target cell; wherein the time of determining the first measurement result of the target cell corresponds to the time of determining the TA value of the target cell; When the terminal device receives a handover command sent by a source network device or the terminal device needs to perform handover, the terminal device determines a second measurement result of the target cell; The terminal device accesses the target cell through a random access process, including: When the absolute value of the difference between the first measurement result and the second measurement result is greater than a first threshold, the terminal device accesses the target cell through a random access procedure.

13. The method according to claim 12, further comprising: When the absolute value of the difference between the first measurement result and the second measurement result is less than or equal to the first threshold, the terminal device performs handover to the target cell.

14. The method according to claim 1, wherein the terminal device accesses the target cell through a random access procedure, comprising: When the terminal device determines that the measurement result of the beam information of the target cell is less than or equal to the second threshold, the terminal device accesses the target cell through a random access process; wherein the beam information of the target cell is indicated by the first information; or When the terminal device determines the beam information of the target cell and there is no beam information with a measurement result greater than a second threshold, the terminal device accesses the target cell through a random access process.

15. The method according to claim 14, further comprising: When the terminal device determines that the measurement result of the beam information of the target cell is greater than the second threshold, the terminal device performs handover to the target cell; or, When the terminal device determines the beam information of the target cell and there is beam information whose measurement result is greater than the second threshold, the terminal device performs switching to the target cell.

16. The method according to any one of claims 1 to 15, wherein the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs handover to the first candidate cell, comprising: If the terminal device fails to access the target cell within the third time period, a connection re-establishment process is triggered, or a first candidate cell is determined and a handover is performed to the first candidate cell.

17. The method according to any one of claim 16, wherein the third duration is greater than the first duration corresponding to the terminal device accessing the target cell through a random access procedure.

18. According to the method described in any one of claims 2-8, 16, and 17, the start time of the timer corresponding to the first duration and / or the third duration is determined according to the time when the terminal device determines to reach the target cell.

19. The method according to any one of claims 1 to 15, wherein the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs handover to the first candidate cell, comprising: When the terminal device determines that the measured value of the beam information of the target cell is less than a third threshold, the connection re-establishment process is triggered, or a first candidate cell is determined and switching is performed to the first candidate cell.

20. The method according to any one of claims 1 to 19, wherein determining the first candidate cell comprises: The first candidate cell is determined according to a measurement result of at least one candidate cell; wherein the at least one candidate cell is indicated by a source network device to the terminal device.

21. The method according to any one of claims 1 to 20, wherein the terminal device determines the target cell or the first information, comprising: The terminal device receives a handover command sent by a source network device, where the handover command carries an identifier of the target cell or the first information; or, The terminal device determines the target cell or the first information based on a measurement result of at least one candidate cell; wherein the at least one candidate cell is indicated to the terminal device by a source network device.

22. The method according to any one of claims 1 to 21, wherein the first information comprises at least one of the following: The index or identifier of the target cell; The TA value of the target cell; The TA difference between the source cell and the target cell; beam information of the target cell; Resource information configured by the target cell for the terminal device; The C-RNTI of the target cell; No random access channel RACH-less handover type indication; L1 / L2 handover type indication.

23. The method according to any one of claims 1 to 22, further comprising: When the terminal device successfully switches to the first candidate cell, storing / generating a first report; or, When the terminal device successfully performs random access to the target cell, a second report is stored / generated.

24. The method according to any one of claims 23, further comprising one of the following: The terminal device sends the first report to the network device corresponding to the first candidate cell; The terminal device sends the second report to the target network device; The terminal device receives a first reporting request sent by a network device corresponding to the first candidate cell, and the terminal device sends the first report to the network device corresponding to the first candidate cell; The terminal device receives a second reporting request sent by the target network device, and the terminal device sends the second report to the target network device; The terminal device sends indication information for indicating that the first report is stored to the network device corresponding to the first candidate cell, the terminal device receives the first reporting request sent by the network device corresponding to the first candidate cell, and the terminal device sends the first report to the network device corresponding to the first candidate cell; The terminal device sends indication information to the target network device to indicate that the second report is stored, the terminal device receives the second reporting request sent by the target network device, and the terminal device sends the second report to the target network device.

25. The method according to any one of claims 1 to 24, wherein before the terminal device accesses the target cell through a random access procedure, or the terminal device triggers a connection re-establishment procedure, or the terminal device determines a first candidate cell and performs handover to the first candidate cell, the method further comprises: The terminal device performs L1 / L2 handover to the target cell; or, The terminal device performs RACH less switching to the target cell.

26. A communication method, the method comprising: The source network device sends an identifier or first information of a target cell to the terminal device; wherein the first information is used to indicate the target cell; The identifier of the target cell or the first information is used by the terminal device to access the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

27. The method according to claim 26, wherein the first information comprises at least one of the following: The index or identifier of the target cell; The TA value of the target cell; A TA difference between the source cell and the target cell; beam information of the target cell; Resource information configured by the target cell for the terminal device; The C-RNTI of the target cell; No random access channel RACH-less handover type indication; L1 / L2 handover type indication.

28. A communication device comprising: a determining unit, configured to: determine a target cell or first information; wherein the first information is used to indicate the target cell; The communication unit is used to: access the target cell through a random access process, or trigger a connection re-establishment process, or perform switching to the first candidate cell determined by the terminal device.

29. A communication device comprising: A communication unit, configured to: send an identifier of a target cell or first information to a terminal device; wherein the first information is used to indicate the target cell; The identifier of the target cell or the first information is used by the terminal device to access the target cell through a random access process, or the terminal device triggers a connection re-establishment process, or the terminal device determines a first candidate cell and performs switching to the first candidate cell.

30. A communication device comprising: A processor and a memory, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the program, the method described in any one of claims 1 to 25 or any one of claims 26 to 27 is implemented.

31. A computer storage medium storing one or more programs, wherein the one or more programs can be executed by one or more processors to implement the method according to any one of claims 1 to 25 or any one of claims 26 to 27.

32. A chip comprising: A processor, configured to call and execute a computer program from a memory to implement the method according to any one of claims 1 to 25 or any one of claims 26 to 27.

33. A computer program product, comprising a computer storage medium storing a computer program, wherein the computer program comprises instructions executable by at least one processor, and wherein when the instructions are executed by the at least one processor, the method of any one of claims 1 to 25 or any one of claims 26 to 27 is implemented.

34. A computer program, which enables a computer to execute the method according to any one of claims 1 to 25 or any one of claims 26 to 27.

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