Communication method and device

Abstract

The present application relates to a communication method and a communication device. The method comprises: a first communication device initiating an advanced uplink synchronization process to a first candidate cell, so as to acquire TA information of the first candidate cell. By means of the embodiments of the present application, a first communication device can initiate an advanced uplink synchronization process, so as to acquire a TA of a first candidate cell, thereby improving the communication quality.

Description

Communication methods and devices Technical Field

[0001] This application relates to the field of communications, and more specifically, to a communication method and apparatus. Background Technology

[0002] New Radio (NR) and other communication systems support handover procedures for connected user equipment (UE). The communication system can transfer the UE's communication link from its original cell to a new cell, i.e., perform the handover process. In some scenarios, the handover process can be triggered by Layer 3 (L3) signaling. To reduce the latency of L3 handover, cell handover triggered by Layer 1 or Layer 2 (L1 / L2) signaling can be supported, i.e., L1 / L2-triggered mobility (LTM). During the LTM execution phase, the UE needs to obtain timing advance (TA) related information.

[0003] Summary of the Invention

[0004] This application provides a communication method, including:

[0005] The first communication device initiates an early uplink synchronization process with the first candidate cell to obtain the timing advance TA information of the first candidate cell.

[0006] This application provides a first communication device, including:

[0007] The transceiver unit is used to initiate an early uplink synchronization process to the first candidate cell in order to obtain the TA information of the first candidate cell.

[0008] This application provides a communication device, including a transceiver, a processor, and a memory. The memory stores a computer program, the transceiver communicates with other devices, and the processor calls and runs the computer program stored in the memory to enable the communication device to perform the aforementioned communication method.

[0009] This application provides a chip for implementing the above-described communication method.

[0010] Specifically, the chip includes a processor for retrieving and running a computer program from memory, causing a device equipped with the chip to perform the aforementioned communication method.

[0011] This application provides a computer-readable storage medium for storing a computer program, which, when run by a device, causes the device to perform the aforementioned communication method.

[0012] This application provides a computer program product, including computer program instructions that cause a computer to execute the above-described communication method.

[0013] This application provides a computer program that, when run on a computer, causes the computer to perform the aforementioned communication method.

[0014] In this embodiment of the application, the first communication device can initiate an early uplink synchronization process to obtain the TA of the first candidate cell, thereby improving communication quality. Attached Figure Description

[0015] Figure 1 is a schematic diagram of an application scenario according to an embodiment of this application.

[0016] Figure 2 is a schematic diagram of the cell handover process based on L3 measurement / signaling.

[0017] Figure 3 is a flowchart of the condition switching process.

[0018] Figure 4 is a schematic diagram of the LTM process.

[0019] Figure 5 is a schematic diagram of the cell handover command.

[0020] Figure 6 is a schematic flowchart of a communication method according to an embodiment of this application.

[0021] Figure 7 is a schematic flowchart of a communication method according to another embodiment of this application.

[0022] Figure 8 is a schematic flowchart of a communication method according to another embodiment of this application.

[0023] Figure 9 is a schematic flowchart of a communication method according to another embodiment of this application.

[0024] Figure 10 is a schematic block diagram of a first communication device according to an embodiment of the present application.

[0025] Figure 11 is a schematic flowchart of a first communication device according to another embodiment of this application.

[0026] Figure 12 is a schematic block diagram of a communication device according to an embodiment of this application.

[0027] Figure 13 is a schematic block diagram of a chip according to an embodiment of this application.

[0028] Figure 14 is a schematic block diagram of a communication system according to an embodiment of this application. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0030] The technical solutions of this application embodiment can be applied to various communication systems, such as: Long Term Evolution (LTE) systems, Advanced Long Term Evolution (LTE-A) systems, New Radio (NR) systems, evolution systems of NR systems, LTE-based access to unlicensed spectrum (LTE-U) systems, NR-based access to unlicensed spectrum (NR-U) systems, Non-Terrestrial Networks (NTN) systems, Universal Mobile Telecommunication System (UMTS), Wireless Local Area Networks (WLAN), Wireless Fidelity (WiFi), 5th-Generation (5G) systems, or other communication systems.

[0031] Traditional communication systems typically support a limited number of connections and are easy to implement. However, with the development of communication technology, mobile communication systems will not only support traditional communication but also, for example, device-to-device (D2D) communication, machine-to-machine (M2M) communication, machine-type communication (MTC), vehicle-to-vehicle (V2V) communication, or vehicle-to-everything (V2X) communication. The embodiments of this application can also be applied to these communication systems.

[0032] In one implementation, the communication system in this application embodiment can be applied to a carrier aggregation (CA) scenario, a dual connectivity (DC) scenario, or a standalone (SA) network deployment scenario.

[0033] In one embodiment, the communication system in this application can be applied to unlicensed spectrum, wherein the unlicensed spectrum can also be considered as shared spectrum; or, the communication system in this application can also be applied to licensed spectrum, wherein the licensed spectrum can also be considered as non-shared spectrum.

[0034] This application describes various embodiments in conjunction with network devices and terminal devices, wherein the terminal device may also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device, etc.

[0035] Terminal devices can be stations (STAION, ST) in WLANs, cellular phones, cordless phones, Session Initiation Protocol (SIP) phones, Wireless Local Loop (WLL) stations, Personal Digital Assistant (PDA) devices, handheld devices with wireless communication capabilities, computing devices or other processing devices connected to a wireless modem, in-vehicle devices, wearable devices, terminal devices in next-generation communication systems such as NR networks, or terminal devices in future evolved Public Land Mobile Network (PLMN) networks, etc.

[0036] In the embodiments of this application, the terminal device can be deployed on land, including indoor or outdoor, handheld, wearable or vehicle-mounted; it can also be deployed on water (such as ships); and it can also be deployed in the air (such as airplanes, balloons and satellites).

[0037] In the embodiments of this application, the terminal device may be a mobile phone, a tablet computer, a computer with wireless transceiver capabilities, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal device in industrial control, a wireless terminal device in self-driving, a wireless terminal device in remote medical care, a wireless terminal device in a smart grid, a wireless terminal device in transportation safety, a wireless terminal device in a smart city, or a wireless terminal device in a smart home, etc.

[0038] By way of example and not limitation, in this embodiment, the terminal device can also be a wearable device. Wearable devices, also known as wearable smart devices, are a general term for devices that utilize wearable technology to intelligently design and develop everyday wearables, such as glasses, gloves, watches, clothing, and shoes. Wearable devices are portable devices that are worn directly on the body or integrated into the user's clothing or accessories. Wearable devices are not merely hardware devices, but also achieve powerful functions through software support, data interaction, and cloud interaction. Broadly speaking, wearable smart devices include those that are feature-rich, large in size, and can achieve complete or partial functions without relying on a smartphone, such as smartwatches or smart glasses, as well as those that focus on a specific type of application function and require the use of other devices such as smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0039] In the embodiments of this application, the network device can be a device for communicating with mobile devices, such as an access point (AP) in a WLAN, an evolved Node B (eNB or eNodeB) in LTE, a relay station or access point, or a vehicle-mounted device, a wearable device, a network device (gNB) in an NR network, or a network device in a future evolved PLMN network or an NTN network, etc.

[0040] By way of example and not limitation, in this embodiment, the network device may have mobility characteristics; for example, the network device may be a mobile device. Optionally, the network device may be a satellite or a balloon station. For example, the satellite may be a low Earth orbit (LEO) satellite, a medium Earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, a high elliptical orbit (HEO) satellite, etc. Optionally, the network device may also be a base station located on land, water, or other similar locations.

[0041] In this embodiment, the network device can provide services to a cell. The terminal device communicates with the network device through the transmission resources (e.g., frequency domain resources, or spectrum resources) used by the cell. The cell can be the cell corresponding to the network device (e.g., a base station). The cell can belong to a macro base station or to a base station corresponding to a small cell. The small cell can include: metro cell, micro cell, pico cell, femto cell, etc. These small cells have the characteristics of small coverage area and low transmission power, and are suitable for providing high-speed data transmission services.

[0042] Figure 1 illustrates an exemplary communication system 100. The communication system includes a network device 110 and two terminal devices 120. In one embodiment, the communication system 100 may include multiple network devices 110, and the coverage area of ​​each network device 110 may include other numbers of terminal devices 120; this embodiment does not limit the scope of the present application.

[0043] In one embodiment, the communication system 100 may also include other network entities such as a Mobility Management Entity (MME) and an Access and Mobility Management Function (AMF), which are not limited in this application.

[0044] Network equipment can be further divided into access network equipment and core network equipment. That is, the wireless communication system also includes multiple core networks used to communicate with the access network equipment. Access network equipment can be evolved Node Bs (eNBs or e-NodeBs) in Long-Term Evolution (LTE), Next-Generation Radio (NR) (mobile communication system), or Authorized Auxiliary Access Long-Term Evolution (LAA-LTE) systems, such as macro base stations, micro base stations (also called "small base stations"), pico base stations, access points (APs), transmission points (TPs), or new generation Node Bs (gNodeBs).

[0045] It should be understood that devices with communication functions in the network / system of this application embodiment can be referred to as communication devices. Taking the communication system shown in Figure 1 as an example, the communication device may include network devices and terminal devices with communication functions. The network devices and terminal devices can be specific devices in this application embodiment, which will not be described in detail here. The communication device may also include other devices in the communication system, such as network controllers, mobility management entities, and other network entities. This application embodiment does not limit this.

[0046] It should be understood that the terms "system" and "network" are often used interchangeably in this document. The term "and / or" in this document merely describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Furthermore, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0047] It should be understood that the term "instruction" mentioned in the embodiments of this application can be a direct instruction, an indirect instruction, or an indication of a relationship. For example, A instructing B can mean that A directly instructs B, such as B being able to obtain information through A; it can also mean that A indirectly instructs B, such as A instructing C, so B can obtain information through C; or it can mean that there is a relationship between A and B.

[0048] In the description of the embodiments of this application, the term "correspondence" may indicate that there is a direct or indirect correspondence between two things, or that there is an association between two things, or that there is a relationship of instruction and being instructed, configuration and being configured, etc.

[0049] To facilitate understanding of the technical solutions of the embodiments of this application, the relevant technologies of the embodiments of this application are described below. The following relevant technologies are optional solutions and can be combined with the technical solutions of the embodiments of this application in any way, and they all fall within the protection scope of the embodiments of this application.

[0050] I. Traditional Switchover Process

[0051] Similar to LTE systems, NR systems support handover procedures for connected UEs. When a user (e.g., a UE) using network services moves from one cell to another, or due to adjustments in radio transmission service load, activation operation and maintenance, equipment failure, or other reasons, in order to ensure communication continuity and service quality, the system must transfer the user's communication link with the original cell to the new cell, i.e., perform a handover process.

[0052] Figure 2 is a schematic diagram of the cell handover process across base stations. An example of the process is as follows:

[0053] S201. The source base station (gNB) triggers handover based on the L3 measurement results reported by the terminal (UE) and sends a handover request (HANDOVER REQUEST) to the target cell through the Xn interface.

[0054] S202. Admission Control is performed at the Target gNB. The Target gNB receives the handover request from the Source Base Station, provides the Radio Resource Control (RRC) configuration for the Target Cell, and feeds it back to the Source Base Station as part of the Handover Request Acknowledgment.

[0055] S203. The source base station sends an RRC reconfiguration instruction to the UE to initiate a handover procedure, as well as RRC configuration information for accessing the target cell.

[0056] S204. UE switches to a new cell. For example, the UE accesses the target cell and sends an RRC reconfiguration complete message to the target cell. In order to establish uplink synchronization with the target cell, the UE needs to initiate a random access procedure to the target cell.

[0057] II. Condition Switching

[0058] The primary goal of conditional handover is to improve the reliability and robustness of user handover, addressing issues such as delayed handover due to excessive preparation time or handover failure caused by a sharp decline in source cell channel quality during the handover process. Conditional handover allows the handover command content to be pre-configured to the UE. When specific conditions are met, the UE can autonomously execute the configuration in the handover command and directly initiate handover access to the target cell that meets the conditions. Since the UE no longer triggers measurement reporting when the handover conditions are met, and the UE has already obtained the configuration in the handover command, measurement reporting and the handover command can be correctly received. Conditional handover significantly improves the handover success rate, especially in high-speed mobile scenarios or scenarios with rapid signal fading in the handover zone. The basic process of conditional handover includes handover preparation, handover execution, and handover completion, as shown in Figure 3.

[0059] Mobility control information provided by AMF (S300.AMF).

[0060] S301. Measurement control and reports are transmitted between the source gNB and the UE.

[0061] S302. Conditional Handover (CHO) Decision.

[0062] S303. The source gNB sends a handover request to the target gNB or another potential target gNB(s).

[0063] S304. The gNB that receives the handover request performs admission control.

[0064] S305.gNB sends a handover request acknowledgment (HANDOVER REQUEST ACKNOWLEDGE).

[0065] S306. The source gNB sends an RRC reconfiguration message to the UE.

[0066] S307. The UE sends an RRC Reconfiguration Complete message to the source gNB. Specifically, S307a. The target gNB performs an Early Status Transition.

[0067] S308. Evaluate the CHO conditions.

[0068] S308a. The target gNB sends a handover success message to the source gNB.

[0069] S308b. The source gNB sends a Serial Number (SN) Status Transmission (SN STATUS TRANSFER) message to the target gNB.

[0070] S308c. The source gNB sends a handover cancellation message to the target gNB and other potential target gNBs.

[0071] III. LTM Process

[0072] In related technologies, the handover process is triggered by L3 signaling (e.g., RRC Reconfiguration). To further reduce the latency of the L3 handover process, the NR R18 mobility project will support cell handover triggered by L1 / L2 signaling, i.e., LTM (L1 / L2-Triggered Mobility). Figure 4 shows the basic process of LTM, which mainly includes the following steps:

[0073] S401. During the LTM preparation phase, the UE, such as the UE in RRC_CONNECTED, reports the L3 measurement results, such as the measurement report, to the base station, such as the gNB. The base station then determines to initiate the LTM process and triggers candidate cell preparation.

[0074] S402. The base station sends an RRC message containing LTM candidate cell configuration, such as an RRC reconfiguration message, to the UE. The number of candidate cells can be one or more.

[0075] S403. The UE stores the LTM candidate cell configuration and sends a reconfiguration completion message to the network, such as an RRC Reconfiguration Complete message.

[0076] S404. During the early synchronization phase, before receiving the LTM cell switch command, the UE can perform uplink / downlink synchronization with the candidate cell in advance (as shown in steps S404a and S404b in Figure 4) to reduce the interruption delay of the handover process. The methods for performing early uplink synchronization include: (1) the UE calculates the TA value of the candidate cell based on the TA value of the current serving cell; (2) the serving cell triggers the UE to send a preamble to the candidate cell through a Physical Downlink Control Channel (PDCCH) order. For point (2), the candidate cell can calculate the TA value of the UE in that cell by receiving the preamble sent by the UE, and inform the serving cell of the TA value and the TAG identifier (Identity, ID) associated with the TA value. The serving cell carries the TA value and the TAG ID associated with the TA value in the LTM cell switch command to trigger the UE to execute RACH-less LTM.

[0077] S405. During the LTM execution phase, the UE performs L1 measurements on each candidate cell and reports the L1 measurement results to the network, such as an L1 measurement report.

[0078] S406. The base station determines the target cell based on the L1 measurement results reported by the UE and instructs the UE to hand over to the target cell through the LTM Cell Switch Media Access Control (MAC) control element (CE). During the handover process, the UE can leave from the source and apply target configurations.

[0079] S407. The UE determines whether to perform RACH-less LTM (with target cell TA value) or RACH-based LTM (without target cell TA value) based on whether there is a target cell TA value. The target cell TA value can be calculated by the UE itself or determined by receiving the LTM Cell Switch MAC CE (i.e., the TA value carried in the LTM Cell Switch MAC CE is not FFF (hexadecimal value)).

[0080] S408. During the LTM completion phase, the UE sends an indication message indicating that LTM has been successfully completed to the target cell.

[0081] In related technologies, LTM is typically triggered by the network side. That is, the UE first reports its L1 measurement results for candidate cells (beams) to the network. The network then determines the target cell based on the received L1 measurement results and sends a cell handover command to the UE via MAC CE. The latency required for measurement result reporting and cell handover command issuance may increase the probability of handover failure.

[0082] Release 17 (R17) of Multiple-Input Multiple-Output (MIMO) supports repetition of uplink PUCCH / PUSCH based on multiple Transmit Receive Points (TRPs), aiming to enhance uplink coverage and transmission reliability. The UE needs to send PUCCH / PUSCH carrying the same content to different TRPs. In this process, the UE uses the same TA value to send uplink data to different TRPs. Release 18 (R18 MIMO) defines a mechanism for multiple antenna panels of the UE to simultaneously transmit PUCCH / PUSCH to multiple TRPs, and supports TRP-specific TA acquisition and indication; that is, the UE's serving cell is assigned two TAGs, each corresponding to one TRP.

[0083] As shown in Figure 5, the LTM cell switch command may include the target configuration ID, timing advance command, TCI state ID, random access preamble index, SS / PBCH index, PRACH mask index, repetition number, etc.

[0084] Candidate cells in R18LTM can also support MIMO 2TA. In this scenario, the UE needs to specify which TAG ID corresponds to the TA in the LTM Cell Switch Command. This information can be determined through indication information associated with the TCI state ID, such as tag-Id-tpr.

[0085] To further enhance the robustness of the LTM process, UE-triggered LTM, also known as Conditional LTM (C-LTM), can be considered. R18 LTM supports early uplink synchronization between the UE and candidate cells. This early uplink synchronization process is triggered by the PDCCH order sent by the source cell, and the UE sends a preamble to the candidate cell based on the PDCCH order. Unlike traditional random access procedures, the UE does not need to listen for the Random Access Response (RAR) after sending the preamble. During the LTM execution phase, the network sends the target cell's TA information (TA value and corresponding TAG ID) to the UE via an LTM cell handover command. From the UE's perspective, during the early synchronization process, the UE does not need to know which TAG under the candidate cell it is sending the preamble for.

[0086] Unlike R18LTM, the C-LTM process requires the UE to autonomously trigger early synchronization and execute LTM. The UE needs to determine the association between TA and TAG.

[0087] Figure 6 is a schematic flowchart of a communication method 600 according to an embodiment of this application. This method can optionally be applied to the system shown in Figure 1, but is not limited thereto. The method includes at least a portion of the following:

[0088] S610, the first communication device initiates an early uplink synchronization process to the first candidate cell to obtain the TA information of the first candidate cell.

[0089] In this embodiment, the first communication device can be a terminal device, such as a UE. If the first communication device needs to hand over from the current serving cell to a candidate cell, the first communication device can proactively trigger an early uplink synchronization process with the first candidate cell. Through the early uplink synchronization process, the first communication device can obtain the TA information of the first candidate cell. The first communication device can perform handover processes such as LTM based on the TA information, thereby improving the handover success rate and communication quality.

[0090] In one implementation, the TA information includes: a TA value and / or TAG information, wherein the TAG information includes a TAG ID and / or indication information for that TAG ID. In this embodiment, the TA value and TAG information can be associated. For example, the TA value and TAG ID can be associated. Similarly, the TA value and the indication information for the TAG ID can be associated. The indication information for the TAG ID can indicate a specific TAG ID. For example, a value of 0 for the indication information for the TAG ID can indicate TAG ID 1. A value of 1 for the indication information for the TAG ID can indicate TAG ID 2.

[0091] In one implementation, the first communication device initiates an early uplink synchronization process with a first candidate cell to obtain the TA information of the first candidate cell, including:

[0092] The first communication device selects a first random access resource associated with a first synchronization resource to send a preamble to the first candidate cell;

[0093] The first communication device receives a first feedback, which includes the TA information of the first candidate cell.

[0094] In this embodiment of the application, during the early uplink synchronization process, the first communication device can select the early uplink synchronization resource itself, or the second communication device, such as a network device, can instruct the early uplink synchronization resource. The early uplink synchronization resource may include a Synchronization Signal Block (SSB). After selecting a first SSB, the first communication device can actively initiate early uplink synchronization, for example, by selecting a first random access resource associated with the first SSB and sending a preamble to the first candidate cell of the first communication device.

[0095] In this embodiment, the first communication device can receive first feedback from the current serving cell (source cell). The first communication device can also receive first feedback from a first candidate cell. In one case, the first feedback may include a TA value and a TAG ID associated with that TA value. In another case, the first feedback may include a TA value and indication information of the TAG ID associated with that TA value.

[0096] In one implementation, the first feedback is carried via a Random Access Response (RAR) or a Media Access Control Unit (MAC CE). For example, if the first feedback is carried via a RAR, the first candidate cell can directly send the first feedback carried by the RAR to the first communication device. Alternatively, if the first feedback is carried via a MAC CE, the first candidate cell can first send the first feedback carried by the MAC CE to the current serving cell (source cell), and then the current serving cell will send it to the first communication device.

[0097] In one implementation, the first feedback originates from the current serving cell and / or a first candidate cell. For example, if the first feedback is carried via a RAR, the first communication device can receive the first feedback from the first candidate cell. Alternatively, if the first feedback is carried via a MAC CE, the first communication device can receive the first feedback from the current serving cell.

[0098] In one implementation, the determination of the first synchronization resource includes at least one of the following:

[0099] The Layer 1 (L1) measurement result of the first synchronization resource is greater than or equal to the first threshold;

[0100] The L1 measurement result of the first synchronization resource is the best among the L1 measurement results of the candidate synchronization resources;

[0101] The difference between the L1 measurement result of the first synchronization resource and the L1 measurement result of the current serving beam is greater than or equal to the second threshold.

[0102] This first synchronization resource belongs to the first synchronization resource set;

[0103] The first synchronization resource is indicated by a downlink channel command.

[0104] In this embodiment, random access resources and beams are bound together. Each SSB can be associated with several random access resources. When selecting the first random access resource associated with an SSB, a random access resource with good beam quality needs to be selected. Therefore, the first SSB can be selected based on the beam measurement results of multiple SSBs.

[0105] In this embodiment, the measurement result threshold can be determined based on the Reference Signal Receiving Power (RSRP) of the SSB, and the first SSB can be selected based on this threshold. For example, if the L1 measurement result, such as the RSRP value, of a certain SSB is greater than or equal to the first RSRP threshold, this SSB can be selected as an early uplink synchronization resource (this SSB is the first SSB). As another example, if the difference between the L1 measurement result, such as the first RSRP value, of a certain SSB and the L1 measurement result, such as the second RSRP value, of the current serving beam is greater than or equal to the second RSRP threshold, this SSB can be selected as an early uplink synchronization resource. Here, the current serving beam is the beam of the current serving cell of the first communication device. If the difference is large, it indicates that the signal quality of the current serving cell is poor, while the signal quality of the target cell or candidate cell is better.

[0106] In this embodiment, the first SSB can also be selected directly based on the measurement results. For example, if among multiple SSBs, the L1 measurement result of a certain SSB, such as the RSRP value, is the largest, that SSB can be selected as the early uplink synchronization resource.

[0107] In this embodiment of the application, the first SSB can also be selected based on the SSB set. For example, the first SSB set includes multiple SSBs, and one SSB can be randomly selected from the first SSB set as the early uplink synchronization resource.

[0108] In this embodiment of the application, if the first communication device receives a PDCCH command from the network device, and the PDCCH command indicates an SSB, then the SSB indicated in the PDCCH command can be used as an early uplink synchronization resource.

[0109] In one implementation, the first set of synchronization resources includes at least one of the following:

[0110] The synchronization resources corresponding to the Transmission Configuration Indicator (TCI) status activated under the first candidate cell;

[0111] All synchronization resources under the first candidate cell;

[0112] Synchronization resources in the L1 measurement configuration associated with the first candidate cell;

[0113] Synchronization resources in the first random access resource configuration;

[0114] The synchronization resources associated with the first timing advance group (TAG) under the first candidate cell, wherein the first timing advance group identifier (TAG ID) corresponding to the first TAG is indicated by downlink channel command.

[0115] For example, the first SSB set consists of SSBs corresponding to the activated TCI states under the first candidate cell. Alternatively, the first SSB set may consist of all SSBs under the first candidate cell. Another example is that the first SSB set consists of SSBs in the L1 measurement configuration associated with the first candidate cell. Yet another example is that the first SSB set consists of SSBs in the first random access resource configuration issued by the network. Furthermore, the current serving cell can support two or more TAGs. Different TAGs are associated with different random access resources. One TAG may be associated with multiple SSBs. The network can instruct the first communication device whether it needs to perform early uplink synchronization with a certain TAG through downlink channel commands such as PDCCH commands. If the first communication device determines that it needs to perform early uplink synchronization through this TAG, i.e., the first TAG, it can determine the multiple SSBs associated with this first TAG, and these SSBs can form the first SSB set.

[0116] Figure 7 is a schematic flowchart of a communication method according to another embodiment of this application. The method may include one or more features of the method described above. In one embodiment, the method further includes:

[0117] S710. The first communication device starts a first timer corresponding to the first TAG ID, where the first TAG ID is the ID of the first TAG associated with the first candidate cell; the first timer is used to control the validity of the TA value associated with the first TAG ID. In this embodiment, when the first timer is running, the TA value associated with the first TAG ID is valid; when the first timer stops, the TA value associated with the first TAG ID is invalid. Thus, the validity of the TA value associated with the TAG ID can be flexibly controlled through the timer.

[0118] In one implementation, the method for determining the first TAG ID includes:

[0119] Determined through the first random access resource;

[0120] Determined by the indication information of the TAG ID corresponding to the first synchronization resource;

[0121] Determined by the TAG information associated with the random access resources in the first configuration information;

[0122] Determined based on the first feedback;

[0123] default value.

[0124] In this embodiment, a first SSB can be selected first, or the TAG ID can be determined first and then the first SSB associated with that TAG ID can be selected. If the first SSB is selected first, the first TAG ID can be determined based on the first SSB.

[0125] For example, a first TAG ID can be determined based on a first random access resource associated with a first SSB. The first TAG ID associated with the first SSB can be provided to the first communication device through the configuration of the first random access resource.

[0126] For example, the indication information of TAG ID can be recorded as tag-Id-ptr. If the indication information of the TAG ID corresponding to the first SSB is 1, the first TAG ID is TAG ID 1; if the indication information of the TAG ID corresponding to the first SSB is 0, the first TAG ID is TAG ID 2.

[0127] For example, the first communication device can receive first configuration information from the second communication device, such as a network device, including the configuration of random access resources. Based on the configuration of the first random access resources, the first TAG ID associated with the first SSB can be obtained.

[0128] For example, after the first communication device sends a preamble using the first random access resource, it can determine the first TAG ID based on the first feedback received, which may include TAG ID or an indication of TAG ID.

[0129] Figure 8 is a schematic flowchart of a communication method according to another embodiment of this application. The method may include one or more features of the method described above. In one embodiment, the method further includes:

[0130] S810, the first communication device receives first configuration information, which includes random access resources for initiating early uplink synchronization to one or more candidate cells.

[0131] In one implementation, the first configuration information further includes at least one of the following:

[0132] The index of the first candidate cell;

[0133] The first random access resource configuration is used to initiate an early uplink synchronization process to the first candidate cell;

[0134] TAG information associated with randomly accessed resources.

[0135] In one implementation, the first random access resource configuration is associated with other candidate cells, and / or the first random access resource configuration is associated with the current serving cell.

[0136] In this embodiment, when the first communication device initiates an early uplink synchronization process with the first candidate cell, it selects a first random access resource configuration corresponding to the current serving cell and / or the candidate cell (when the candidate cell becomes the serving cell). For example, in addition to the first candidate cell, there are two other candidate cells, namely a second candidate cell and a third candidate cell. The current serving cell is associated with random access resource configuration #1, the second candidate cell is associated with random access resource configuration #2, and the third candidate cell is associated with random access resource configuration #3. When the UE initiates an early uplink synchronization process with the first candidate cell from the current serving cell, it uses random access resource configuration #1 to initiate the early uplink synchronization process with the first candidate cell (sending a preamble); when the UE accesses the second candidate cell through the LTM process, that is, when the second candidate cell becomes the current serving cell, it uses random access resource configuration #2 to initiate an early uplink synchronization process with the first candidate cell (sending a preamble).

[0137] In one implementation, the TAG information associated with the random access resource includes: TAG ID indication information corresponding to the random access resource, or TAG ID indication information corresponding to a subset of random access resources. For example, the random access resource or subset of random access resources may include at least one of the following: SSB / SSB set, preamble / preamble set, random access channel timing (RACH Occasion, RO) / RO set, etc.

[0138] Figure 9 is a schematic flowchart of a communication method according to another embodiment of this application. The method may include one or more features of the method described above. In one embodiment, the method further includes:

[0139] S910, the first communication device initiates an LTM procedure to the first candidate cell. In this embodiment, after prior uplink synchronization, the first communication device can initiate an LTM procedure to the first candidate cell based on its state.

[0140] In one implementation, the first communication device initiates an LTM procedure to the first candidate cell, including:

[0141] The first communication device selects the second synchronization resource;

[0142] The first communication device initiates LTM to the first candidate cell based on the second synchronization resource.

[0143] In this embodiment, if the previously selected first synchronization resource is still valid, an LTM can be initiated for the first candidate cell based on that first synchronization resource. During the LTM process, the previously selected first synchronization resource may have expired or become invalid, so a second synchronization resource can be reselected. For example, the first communication device reselects a second SSB, and based on the selected second SSB, determines whether to initiate a RACH-less LTM or a RACH-based LTM for the first LTM. After determining the second SSB, the TCI state corresponding to the second SSB is applied, and / or, a pre-configured uplink resource associated with the second SSB is selected to perform the initial uplink transmission.

[0144] In one implementation, selecting the second synchronization resource includes selecting the second synchronization resource based on the L1 measurement results of the synchronization resource, specifically including at least one of the following:

[0145] In the second set of synchronization resources, select the synchronization resources whose L1 measurement results are greater than the third threshold as the second synchronization resources;

[0146] If there is no synchronization resource in the second synchronization resource set whose L1 measurement result is greater than the third threshold, a synchronization resource is randomly selected from the second synchronization resource set as the second synchronization resource.

[0147] In this embodiment, a second synchronization resource, such as a second SSB set, can be selected based on a second synchronization resource set, such as a second SSB set. For example, an SSB whose L1 measurement result is greater than the third RSRP is selected from the second SSB set as the second SSB. If there is no SSB in the second SSB set whose L1 measurement result is greater than the second RSRP, then an SSB is randomly selected from the second SSB set as the second SSB.

[0148] In one implementation, the second set of synchronization resources includes at least one of the following examples:

[0149] All synchronization resources under the first candidate cell;

[0150] All synchronization resources in the L1 measurement configuration associated with the first candidate cell;

[0151] The synchronization resources corresponding to the activated TCI state under the first candidate cell.

[0152] In one implementation, the first communication device initiates LTM to the first candidate cell based on the second synchronization resource, including:

[0153] If the first communication device has a valid TA value for the TAG corresponding to the second synchronization resource, it initiates an LTM without a random access procedure to the first candidate cell; or

[0154] If the first communication device does not have a valid TA value for the TAG corresponding to the second synchronization resource, it initiates an LTM based on a random access procedure to the first candidate cell.

[0155] In this embodiment of the application, if the second synchronization resource set is any of the examples above, it can be further determined whether the TAG corresponding to the second SSB has a valid TA value (also called a valid TA). If it does, the first communication device initiates a RACH-less LTM to the first candidate cell; otherwise, it initiates a RACH-based LTM.

[0156] In one implementation, the TAGs corresponding to the synchronization resources in the second set of synchronization resources have valid TA values.

[0157] In one implementation, the first communication device initiates LTM with the first candidate cell based on the second synchronization resource, including:

[0158] The first communication device initiates an LTM (Learning Without a Random Access Procedure) to the first candidate cell; or

[0159] If there are no synchronization resources in the second synchronization resource set whose L1 measurement results are greater than the third threshold, the first communication device modifies the second synchronization resource set to include at least one of the following: all synchronization resources under the first candidate cell; all synchronization resources in the L1 measurement configuration associated with the first candidate cell; synchronization resources corresponding to the activated TCI state under the first candidate cell; and the first communication device reselects the second synchronization resource based on the L1 measurement results of the synchronization resources.

[0160] For example, if the TAG corresponding to an SSB in the second SSB set has a valid TA value, the first communication device can directly initiate RACH-less LTM to the first candidate cell. Alternatively, if the TAG corresponding to an SSB in the second SSB set has a valid TA value, but there are no SSBs in the second SSB set whose L1 measurement results are greater than the second RSRP threshold, the method for determining the second SSB set can be changed. For example, the second SSB set could include all SSBs under the first candidate cell. Or, the second SSB set could include all SSBs in the L1 measurement configuration associated with the first candidate cell. Or, the second SSB set could include SSBs corresponding to the activated TCI state under the first candidate cell. Then, a second SSB is reselected based on the second SSB set.

[0161] In one implementation, the selection of the second synchronization resource includes randomly selecting a synchronization resource from the second set of synchronization resources as the second synchronization resource. For example, after determining the second set of SSBs, an SSB can also be randomly selected from the second set of SSBs as the second SSB.

[0162] In one implementation, the TAGs corresponding to the synchronization resources in the second set of synchronization resources have valid TA values.

[0163] In one implementation, the first communication device initiates LTM to the first candidate cell based on the second synchronization resource, including:

[0164] The first communication device initiates an LTM (Local Time Management) without a random access procedure to the first candidate cell.

[0165] In one implementation, the TAG corresponding to the synchronization resources in the second synchronization resource set has a valid TA value, including at least one of the following:

[0166] The TAG ID corresponding to the synchronization resource in the second synchronization resource set is the same as the TAG ID corresponding to the TA value obtained in advance uplink synchronization;

[0167] The first timer for the TAG ID corresponding to the synchronization resource in the second synchronization resource set is in running state.

[0168] For example, if the TAG corresponding to the SSB in the second SSB set has a valid TA value, it may include the following situations: 1) The TAG ID corresponding to the SSB in the second SSB set is the same as the TAG ID corresponding to the TA value obtained in advance through uplink synchronization; 2) The first timer of the TAG ID corresponding to the SSB in the second SSB set is in running state.

[0169] The communication method in this application embodiment may include a method for obtaining TA in advance during a conditional handover process. The early uplink synchronization process for conditional handover can configure random access resources for early synchronization and determine the association between TA and TAG.

[0170] This application embodiment can provide a method for the UE to select the SSB when performing LTM, and determine whether to perform RACH-less LTM or RACH-based LTM.

[0171] Specific examples are as follows:

[0172] Example 1

[0173] I. The UE triggers an early uplink synchronization process with the first candidate cell, including:

[0174] 1-1. Determine the first SSB, and select the random access resource associated with the first SSB to send a preamble to the first candidate cell; wherein, the random access resource associated with the first SSB belongs to the first random access resource configuration; the method of determining the first SSB includes (the following conditions are AND / OR relationships):

[0175] (1) The L1 measurement result of the first SSB is greater than or equal to the first RSRP threshold.

[0176] (2) The first SSB is the SSB with the best L1 measurement results.

[0177] (3) The L1 measurement result of the first SSB is greater than or equal to the sum of the L1 measurement result of the current serving beam and the second RSRP threshold; or the difference between the L1 measurement result of the first SSB and the L1 measurement result of the current serving beam is greater than or equal to the second RSRP threshold.

[0178] (4) The first SSB belongs to the first SSB set. Furthermore, the composition of the first SSB set includes the following examples:

[0179] The first SSB set consists of the SSBs corresponding to the activated TCI states under the first candidate cell;

[0180] The first SSB set consists of all SSBs under the first candidate cell;

[0181] The first SSB set consists of the SSBs in the L1 measurement configuration associated with the first candidate cell;

[0182] The first SSB set consists of the SSBs in the first random access resource configuration;

[0183] The first SSB set consists of SSBs associated with the first candidate cell and the first TAG, wherein the TAG ID corresponding to the first TAG is indicated by the PDCCH command (order);

[0184] (5) The first SSB is indicated by the PDCCH order.

[0185] 1-2. Receive first feedback, which includes at least the TA information of the first candidate cell. In one implementation, the first feedback is a RAR, or the first feedback is carried by a MAC CE. Further, the UE receives the first feedback from the source cell (carried by a MAC CE), or the UE receives the first feedback (RAR) from the first candidate cell. In another implementation, the first feedback includes TA information of multiple candidate cells. TA information includes TA values ​​and / or TAG information. For example, TAG information is a TAG ID. Alternatively, TAG information can be represented by 0 / 1. When TAG information is 0, it represents the TAG ID corresponding to tag2-Id in the RRC configuration. When TAG information is 1, it represents the TAG ID corresponding to tag1-Id in the RRC configuration.

[0186] 1-3. Start the first timer corresponding to the first TAG ID, including:

[0187] Option 1 (Opt1): The first TAG ID is determined by the first random access resource and / or the indication information corresponding to the first SSB, such as tag-Id-ptr. Accordingly, the first configuration needs to include the random access resource associated TAG information containing the following first configuration information.

[0188] Option 2 (Opt2): The first TAG ID is included in the first feedback;

[0189] Option 3 (Opt3): The first TAG ID defaults to 0 or 1.

[0190] 2. Before initiating early uplink synchronization to the first candidate cell, the UE receives first configuration information. The first configuration information includes random access resources for initiating early uplink synchronization to at least one candidate cell. For each candidate cell (e.g., the first candidate cell), the first configuration information further includes at least one of the following:

[0191] (1) First candidate cell index.

[0192] (2) A first random access resource configuration, used to initiate an early uplink synchronization procedure to a first candidate cell. In one implementation, the first random access resource configuration is associated with other candidate cells and / or the current serving cell. When the UE initiates an early uplink synchronization procedure to the first candidate cell, it selects the first random access resource configuration corresponding to the current serving cell and / or the candidate cell (e.g., when the candidate cell becomes the serving cell).

[0193] For example, besides the first candidate cell, there are two other candidate cells: the second candidate cell and the third candidate cell. The current serving cell is associated with random access resource configuration #1, the second candidate cell with random access resource configuration #2, and the third candidate cell with random access resource configuration #3. When the UE initiates an early uplink synchronization procedure from the current serving cell to the first candidate cell, it uses random access resource configuration #1. When the UE accesses the second candidate cell through the LTM procedure, i.e., when the second candidate cell becomes the current serving cell, it uses random access resource configuration #2 to initiate an early uplink synchronization procedure from the first candidate cell.

[0194] (3) TAG information associated with random access resources, such as the tag-Id-ptr corresponding to random access resources or subsets of random access resources (e.g., SSB / SSB set, and / or preamble / preamble set, and / or RO / RO set).

[0195] Example 2

[0196] The UE initiates an LTM procedure to the first candidate cell, including selecting a second SSB based on at least one of the following methods:

[0197] Opt1: Select a second SSB based on the L1 measurement result of the SSB, including selecting an SSB whose L1 measurement result is greater than the second RSRP from the second SSB set as the second SSB; if there is no SSB in the second SSB set whose L1 measurement result is greater than the second RSRP, then randomly select an SSB from the second SSB set as the second SSB.

[0198] The second SSB set has at least one of the following characteristics:

[0199] (1) Includes all SSBs under the first candidate cell, or all SSBs in the L1 measurement configuration associated with the first candidate cell;

[0200] (2) It consists of the SSB corresponding to the TCI state activated under the first candidate cell;

[0201] (3) The TAG corresponding to the SSB has a valid TA value, including: 1) The TAG ID corresponding to the SSB is the same as the TAG ID corresponding to the TA value obtained in advance through uplink synchronization; 2) The first timer of the TAG ID corresponding to the SSB is in running state.

[0202] In one implementation, the second SSB set is as described in (1) or (2) above. The UE further determines whether there is a valid TA for the TAG corresponding to the second SSB. If there is, the UE initiates RACH-less LTM to the first candidate cell; otherwise, it initiates RACH-based LTM.

[0203] In another implementation, the second SSB set is as described in (3), and the UE initiates RACH-less LTM to the first candidate cell.

[0204] In another implementation, the second SSB set is as described in (3). If there is no SSB in the second SSB set whose L1 measurement result is greater than the second RSRP threshold, the UE considers the second SSB set to be as described in (1) or (2), and reselects the second SSB based on the above rules.

[0205] Opt2: Randomly select an SSB from the second SSB set as the second SSB, wherein the second SSB set is as described in (3) above, and the UE initiates RACH-less LTM to the first candidate cell.

[0206] According to the scheme provided in the embodiments of this application, it is clarified that during the Conditional LTM process, uplink resources that can be synchronized early and the association between TA and TAG can be determined, thereby improving the handover success rate and communication quality.

[0207] Figure 10 is a schematic block diagram of a first communication device 1000 according to an embodiment of the present application. The first communication device 1000 may include:

[0208] The transceiver unit 1010 is used to initiate an early uplink synchronization process to the first candidate cell in order to obtain the TA information of the first candidate cell.

[0209] In one implementation, the TA information includes: TA value and / or TAG information, wherein the TAG information includes TAG ID and / or indication information of the TAG ID.

[0210] In one embodiment, the transceiver unit 1010 is used for:

[0211] Select the first random access resource associated with the first synchronization resource and send the preamble to the first candidate cell;

[0212] Receive the first feedback, which includes the TA information of the first candidate cell.

[0213] In one implementation, the first feedback is carried via RAR or MAC CE.

[0214] In one implementation, the first feedback comes from the current serving cell and / or the first candidate cell.

[0215] In one implementation, the determination of the first synchronization resource includes at least one of the following:

[0216] The L1 measurement result of the first synchronization resource is greater than or equal to the first threshold;

[0217] The L1 measurement result of the first synchronization resource is the best among the L1 measurement results of the candidate synchronization resources;

[0218] The difference between the L1 measurement result of the first synchronization resource and the L1 measurement result of the current serving beam is greater than or equal to the second threshold.

[0219] This first synchronization resource belongs to the first synchronization resource set;

[0220] The first synchronization resource is indicated by a downlink channel command.

[0221] In one implementation, the first set of synchronization resources includes at least one of the following:

[0222] The synchronization resources corresponding to the Transmission Configuration Indicator (TCI) status activated under the first candidate cell;

[0223] All synchronization resources under the first candidate cell;

[0224] Synchronization resources in the L1 measurement configuration associated with the first candidate cell;

[0225] Synchronization resources in the first random access resource configuration;

[0226] The synchronization resources associated with the first timing advance group TAG under the first candidate cell, wherein the first timing advance group identifier TAG ID corresponding to the first TAG is indicated by the downlink channel command.

[0227] Figure 11 is a schematic flowchart of a first communication device 1100 according to another embodiment of this application. The method may include one or more features of the device described above. In one embodiment, the device further includes:

[0228] Processing unit 1110 is used to start a first timer corresponding to the first TAG ID, the first TAG ID being the ID of the first TAG associated with the first candidate cell; the first timer is used to control the validity of the TA value associated with the first TAG ID.

[0229] In one implementation, the method for determining the first TAG ID includes:

[0230] Determined through the first random access resource;

[0231] Determined by the indication information of the TAG ID corresponding to the first synchronization resource;

[0232] Determined by the TAG information associated with the random access resources in the first configuration information;

[0233] Determined based on the first feedback;

[0234] default value.

[0235] In one embodiment, the transceiver unit 1010 is further configured to receive first configuration information, which includes random access resources for initiating early uplink synchronization to one or more candidate cells.

[0236] In one implementation, the first configuration information further includes at least one of the following:

[0237] The index of the first candidate cell;

[0238] The first random access resource configuration is used to initiate an early uplink synchronization process to the first candidate cell;

[0239] TAG information associated with randomly accessed resources.

[0240] In one implementation, the first random access resource configuration is associated with other candidate cells, and / or the first random access resource configuration is associated with the current serving cell.

[0241] In one implementation, the TAG information associated with the random access resource includes: TAG ID indication information corresponding to the random access resource, or TAG ID indication information corresponding to a subset of random access resources.

[0242] In one implementation, the transceiver unit 1010 is further configured to initiate an LTM process to the first candidate cell.

[0243] In one implementation, the transceiver unit 1010 is further configured to select a second synchronization resource and initiate LTM to the first candidate cell based on the second synchronization resource.

[0244] In one implementation, the transceiver unit 1010 selects the second synchronization resource based on L1 measurement results of the synchronization resource, specifically including at least one of the following:

[0245] In the second set of synchronization resources, select the synchronization resources whose L1 measurement results are greater than the third threshold as the second synchronization resources;

[0246] If there is no synchronization resource in the second synchronization resource set whose L1 measurement result is greater than the third threshold, a synchronization resource is randomly selected from the second synchronization resource set as the second synchronization resource.

[0247] In one implementation, the second set of synchronization resources includes at least one of the following:

[0248] All synchronization resources under the first candidate cell;

[0249] All synchronization resources in the L1 measurement configuration associated with the first candidate cell;

[0250] The synchronization resources corresponding to the activated TCI state under the first candidate cell.

[0251] In one implementation, the transceiver unit 1010 is further configured to initiate an LTM without a random access procedure to the first candidate cell if a valid TA value exists for the TAG corresponding to the second synchronization resource; or

[0252] If there is no valid TA value for the TAG corresponding to the second synchronization resource, an LTM based on the random access procedure is initiated for the first candidate cell.

[0253] In one implementation, the TAGs corresponding to the synchronization resources in the second set of synchronization resources have valid TA values.

[0254] In one embodiment, the transceiver unit 1010 is further configured to perform at least one of the following:

[0255] Initiate an LTM without a random access procedure to the first candidate cell; or

[0256] If there are no synchronization resources in the second synchronization resource set whose L1 measurement results are greater than the third threshold, the second synchronization resource set is modified to include at least one of the following: all synchronization resources under the first candidate cell; all synchronization resources in the L1 measurement configuration associated with the first candidate cell; synchronization resources corresponding to the activated TCI state under the first candidate cell; and the first communication device reselects the second synchronization resource based on the L1 measurement results of the synchronization resources.

[0257] In one implementation, the selection method for the second synchronization resource includes:

[0258] Randomly select a synchronization resource from the second set of synchronization resources as the second synchronization resource.

[0259] In one implementation, the TAGs corresponding to the synchronization resources in the second set of synchronization resources have valid TA values.

[0260] In one implementation, the transceiver unit 1010 is further configured to initiate LTM without a random access procedure to the first candidate cell.

[0261] In one implementation, the TAG corresponding to the synchronization resources in the second synchronization resource set has a valid TA value, including at least one of the following:

[0262] The TAG ID corresponding to the synchronization resource in the second synchronization resource set is the same as the TAG ID corresponding to the TA value obtained in advance uplink synchronization;

[0263] The first timer for the TAG ID corresponding to the synchronization resource in the second synchronization resource set is in running state.

[0264] The first communication devices 1000 and 1100 in this application embodiment can realize the corresponding functions of the first communication devices in the aforementioned method embodiments. The processes, functions, implementation methods, and beneficial effects of each module (sub-module, unit, or component, etc.) in the first communication devices 1000 and 1100 can be found in the corresponding descriptions in the above method embodiments, and will not be repeated here. It should be noted that the functions described for each module (sub-module, unit, or component, etc.) in the first communication devices 1000 and 1100 in the application embodiments can be implemented by different modules (sub-modules, units, or components, etc.) or by the same module (sub-module, unit, or component, etc.).

[0265] Figure 12 is a schematic structural diagram of a communication device 1200 according to an embodiment of this application. The communication device 1200 includes a processor 1210, which can call and run computer programs from memory to enable the communication device 1200 to implement the methods in the embodiments of this application.

[0266] In one embodiment, the communication device 1200 may further include a memory 1220. The processor 1210 can retrieve and run computer programs from the memory 1220 to enable the communication device 1200 to implement the methods described in the embodiments of this application.

[0267] The memory 1220 can be a separate device independent of the processor 1210, or it can be integrated into the processor 1210.

[0268] In one embodiment, the communication device 1200 may further include a transceiver 1230, and the processor 1210 may control the transceiver 1230 to communicate with other devices. Specifically, it may send information or data to other devices or receive information or data sent by other devices.

[0269] The transceiver 1230 may include a transmitter and a receiver. The transceiver 1230 may further include an antenna, and the number of antennas may be one or more.

[0270] In one embodiment, the communication device 1200 may be the first communication device in the embodiments of this application, and the communication device 1200 may implement the corresponding processes implemented by the first communication device in the various methods of the embodiments of this application. For the sake of brevity, it will not be described in detail here.

[0271] Figure 13 is a schematic structural diagram of a chip 1300 according to an embodiment of this application. The chip 1300 includes a processor 1310, which can call and run computer programs from memory to implement the methods in the embodiments of this application.

[0272] In one embodiment, chip 1300 may further include memory 1320. Processor 1310 can retrieve and run computer programs from memory 1320 to implement the method executed by the first communication device in this embodiment.

[0273] The memory 1320 can be a separate device independent of the processor 1310, or it can be integrated into the processor 1310.

[0274] In one embodiment, the chip 1300 may further include an input interface 1330. The processor 1310 can control the input interface 1330 to communicate with other devices or chips; specifically, it can acquire information or data sent by other devices or chips.

[0275] In one embodiment, the chip 1300 may further include an output interface 1340. The processor 1310 can control the output interface 1340 to communicate with other devices or chips; specifically, it can output information or data to other devices or chips.

[0276] In one implementation, the chip can be applied to the first communication device in the embodiments of this application, and the chip can implement the corresponding processes implemented by the first communication device in the various methods of the embodiments of this application. For the sake of brevity, it will not be described in detail here.

[0277] The chips used in the first communication device can be the same chips or different chips.

[0278] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0279] The processors mentioned above can be general-purpose processors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), or other programmable logic devices, transistor logic devices, discrete hardware components, etc. Among them, the general-purpose processors mentioned above can be microprocessors or any conventional processor.

[0280] The aforementioned memory can be volatile memory or non-volatile memory, or a combination of both. Non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM).

[0281] It should be understood that the above-described memory is exemplary and not a limiting description. For example, the memory in the embodiments of this 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 memory bus RAM (DR RAM), etc. That is to say, the memory in the embodiments of this application is intended to include, but is not limited to, these and any other suitable types of memory.

[0282] Figure 14 is a schematic block diagram of a communication system 1400 according to an embodiment of the present application. The communication system 1400 includes a first communication device 1410 and a second communication device 1420.

[0283] The first communication device 1410 is used to initiate an early uplink synchronization process to the first candidate cell in order to obtain the TA information of the first candidate cell.

[0284] The second communication device 1420 is used to send the TA information of the first candidate cell to the first communication device.

[0285] The first communication device 1410 can be used to implement the corresponding functions implemented by the first communication device in the above method, and the second communication device 1420 can be used to implement the corresponding functions implemented by the second communication device in the above method. For the sake of brevity, further details are omitted here.

[0286] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. This computer program product includes one or more computer instructions. When these computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives (SSDs)).

[0287] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0288] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0289] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method, comprising: The first communication device initiates an early uplink synchronization process to the first candidate cell in order to obtain the early timing TA information of the first candidate cell.

2. The method according to claim 1, wherein, The TA information includes: TA value and / or TAG information, wherein the TAG information includes TAG ID and / or indication information of the TAG ID.

3. The method according to claim 1 or 2, wherein, The first communication device initiates an early uplink synchronization process with the first candidate cell to obtain the TA information of the first candidate cell, including: The first communication device selects a first random access resource associated with a first synchronization resource to send a preamble to the first candidate cell; The first communication device receives a first feedback, which includes the TA information of the first candidate cell.

4. The method according to claim 3, wherein, The first feedback is carried by the Random Access Response (RAR) or the Media Access Control Unit (MAC CE).

5. The method according to claim 3 or 4, wherein, The first feedback comes from the current serving cell and / or the first candidate cell.

6. The method according to any one of claims 3 to 5, wherein, The method for determining the first synchronization resource includes at least one of the following: The Layer 1 (L1) measurement result of the first synchronization resource is greater than or equal to the first threshold. The L1 measurement result of the first synchronization resource is the best among the L1 measurement results of the candidate synchronization resources; The difference between the L1 measurement result of the first synchronization resource and the L1 measurement result of the current serving beam is greater than or equal to the second threshold. The first synchronization resource belongs to the first synchronization resource set; The first synchronization resource indicated by the downlink channel command.

7. The method according to claim 6, wherein, The first set of synchronization resources includes at least one of the following: The transmission configuration activated in the first candidate cell indicates the synchronization resources corresponding to the TCI state; All synchronization resources under the first candidate cell; Synchronization resources in the L1 measurement configuration associated with the first candidate cell; Synchronization resources in the first random access resource configuration; The synchronization resources associated with the first timing advance group TAG under the first candidate cell, wherein the first timing advance group identifier TAG ID corresponding to the first TAG is indicated by downlink channel command.

8. The method according to any one of claims 1 to 7, wherein, The method further includes: The first communication device starts a first timer corresponding to the first TAG ID, where the first TAG ID is the ID of the first TAG associated with the first candidate cell; the first timer is used to control the validity of the TA value associated with the first TAG ID.

9. The method according to claim 8, wherein, The methods for determining the first TAG ID include: Determined through the first random access resource; Determined by the indication information of the TAG ID corresponding to the first synchronization resource; Determined by the TAG information associated with the random access resources in the first configuration information; Determined based on the first feedback; default value.

10. The method according to any one of claims 1 to 9, wherein, The method further includes: The first communication device receives first configuration information, which includes random access resources for initiating early uplink synchronization to one or more candidate cells.

11. The method according to claim 10, wherein, The first configuration information also includes at least one of the following: The index of the first candidate cell; The first random access resource configuration is used to initiate an early uplink synchronization process to the first candidate cell; TAG information associated with randomly accessed resources.

12. The method according to claim 11, wherein, The first random access resource configuration is associated with other candidate cells, and / or the first random access resource configuration is associated with the current serving cell.

13. The method according to claim 12, wherein, The TAG information associated with the random access resources includes: TAG ID indication information corresponding to the random access resources, or TAG ID indication information corresponding to a subset of random access resources.

14. The method according to any one of claims 1 to 13, wherein, The method further includes: The first communication device initiates an L1 and / or Layer 2 L2 triggered mobility LTM procedure to the first candidate cell.

15. The method according to claim 14, wherein, The first communication device initiates an LTM procedure to the first candidate cell, including: The first communication device selects the second synchronization resource; The first communication device initiates LTM to the first candidate cell based on the second synchronization resource.

16. The method according to claim 15, wherein, Selecting a second synchronization resource includes selecting a second synchronization resource based on the L1 measurement results of the synchronization resource, and the specific methods include at least one of the following: In the second set of synchronization resources, select the synchronization resources whose L1 measurement results are greater than the third threshold as the second synchronization resources; If there is no synchronization resource in the second synchronization resource set whose L1 measurement result is greater than the third threshold, a synchronization resource is randomly selected from the second synchronization resource set as the second synchronization resource.

17. The method according to claim 16, wherein, The second set of synchronization resources includes at least one of the following: All synchronization resources under the first candidate cell; All synchronization resources in the L1 measurement configuration associated with the first candidate cell; The synchronization resources corresponding to the activated TCI state under the first candidate cell.

18. The method according to claim 17, wherein, The first communication device initiates LTM to the first candidate cell based on the second synchronization resource, including: If the first communication device has a valid TA value for the TAG corresponding to the second synchronization resource, it initiates an LTM without a random access procedure to the first candidate cell; or If the first communication device does not have a valid TA value for the TAG corresponding to the second synchronization resource, it initiates an LTM based on a random access procedure to the first candidate cell.

19. The method of claim 16, wherein, The TAGs corresponding to the synchronization resources in the second set of synchronization resources have valid TA values.

20. The method according to claim 19, wherein, The first communication device initiates LTM to the first candidate cell based on the second synchronization resource, including: The first communication device initiates an LTM (Local Time Transfer) without a random access procedure to the first candidate cell; or If there is no synchronization resource in the second synchronization resource set whose L1 measurement result is greater than the third threshold, the first communication device modifies the second synchronization resource set to include at least one of the following: all synchronization resources under the first candidate cell; all synchronization resources in the L1 measurement configuration associated with the first candidate cell; synchronization resources corresponding to the activated TCI state under the first candidate cell; and the first communication device reselects the second synchronization resource based on the L1 measurement result of the synchronization resource.

21. The method according to claim 15, wherein, The selection methods for the second synchronization resource include: Randomly select a synchronization resource from the second set of synchronization resources as the second synchronization resource.

22. The method according to claim 21, wherein, The TAGs corresponding to the synchronization resources in the second set of synchronization resources have valid TA values.

23. The method according to claim 22, wherein, The first communication device initiates LTM to the first candidate cell based on the second synchronization resource, including: The first communication device initiates an LTM (Local Time Management) without a random access procedure to the first candidate cell.

24. The method according to claim 19 or 22, wherein, The synchronization resources in the second set of synchronization resources have valid TA values ​​for their corresponding TAGs, including at least one of the following: The TAG ID corresponding to the synchronization resource in the second synchronization resource set is the same as the TAG ID corresponding to the TA value obtained in advance uplink synchronization; The first timer for the TAG ID corresponding to the synchronization resource in the second synchronization resource set is in running state.

25. A first communication device, comprising: The transceiver unit is used to initiate an early uplink synchronization process to the first candidate cell in order to obtain the TA information of the first candidate cell.

26. The method of claim 25, wherein, The TA information includes: TA value and / or TAG information, wherein the TAG information includes TAG ID and / or indication information of the TAG ID.

27. The device according to claim 25 or 26, wherein, The transceiver unit is used for: Select the first random access resource associated with the first synchronization resource and send the preamble to the first candidate cell; Receive first feedback, which includes the TA information of the first candidate cell.

28. The device according to claim 27, wherein, The first feedback is carried via RAR or MAC CE.

29. The device according to claim 27 or 28, wherein, The first feedback comes from the current serving cell and / or the first candidate cell.

30. The device according to any one of claims 27 to 29, wherein, The method for determining the first synchronization resource includes at least one of the following: The L1 measurement result of the first synchronization resource is greater than or equal to the first threshold; The L1 measurement result of the first synchronization resource is the best among the L1 measurement results of the candidate synchronization resources; The difference between the L1 measurement result of the first synchronization resource and the L1 measurement result of the current serving beam is greater than or equal to the second threshold. The first synchronization resource belongs to the first synchronization resource set; The first synchronization resource is indicated by a downlink channel command.

31. The device according to claim 30, wherein, The first set of synchronization resources includes at least one of the following: The synchronization resources corresponding to the activated TCI state under the first candidate cell; All synchronization resources under the first candidate cell; Synchronization resources in the L1 measurement configuration associated with the first candidate cell; Synchronization resources in the first random access resource configuration; The synchronization resources associated with the first TAG under the first candidate cell, wherein the first TAG ID corresponding to the first TAG is indicated by a downlink channel command.

32. The device according to any one of claims 25 to 31, wherein, The device also includes: The processing unit is configured to start a first timer corresponding to the first TAG ID, wherein the first TAG ID is the ID of the first TAG associated with the first candidate cell; the first timer is configured to control the validity of the TA value associated with the first TAG ID.

33. The device according to claim 32, wherein, The methods for determining the first TAG ID include: Determined through the first random access resource; Determined by the indication information of the TAG ID corresponding to the first synchronization resource; Determined by the TAG information associated with the random access resources in the first configuration information; Determined based on the first feedback; default value.

34. The device according to any one of claims 25 to 33, wherein, The transceiver unit is further configured to receive first configuration information, which includes random access resources for initiating early uplink synchronization to one or more candidate cells.

35. The device according to claim 34, wherein, The first configuration information also includes at least one of the following: The index of the first candidate cell; The first random access resource configuration is used to initiate an early uplink synchronization process to the first candidate cell; TAG information associated with randomly accessed resources.

36. The device according to claim 35, wherein, The first random access resource configuration is associated with other candidate cells, and / or the first random access resource configuration is associated with the current serving cell.

37. The device according to claim 36, wherein, The TAG information associated with the random access resources includes: TAG ID indication information corresponding to the random access resources, or TAG ID indication information corresponding to a subset of random access resources.

38. The device according to any one of claims 25 to 37, wherein, The transceiver unit is also used to initiate an LTM process to the first candidate cell.

39. The device according to claim 38, wherein, The transceiver unit is further configured to select a second synchronization resource and initiate LTM to the first candidate cell based on the second synchronization resource.

40. The device according to claim 39, wherein, The transceiver unit selects the second synchronization resource based on the L1 measurement results of the synchronization resource, and the specific methods include at least one of the following: In the second set of synchronization resources, select the synchronization resources whose L1 measurement results are greater than the third threshold as the second synchronization resources; If there is no synchronization resource in the second synchronization resource set whose L1 measurement result is greater than the third threshold, a synchronization resource is randomly selected from the second synchronization resource set as the second synchronization resource.

41. The device according to claim 40, wherein, The second set of synchronization resources includes at least one of the following: All synchronization resources under the first candidate cell; All synchronization resources in the L1 measurement configuration associated with the first candidate cell; The synchronization resources corresponding to the activated TCI state under the first candidate cell.

42. The device according to claim 41, wherein, The transceiver unit is also configured to perform at least one of the following: If a valid TA value exists for the TAG corresponding to the second synchronization resource, initiate an LTM without a random access procedure to the first candidate cell. or If there is no valid TA value for the TAG corresponding to the second synchronization resource, an LTM based on the random access procedure is initiated for the first candidate cell.

43. The device according to claim 40, wherein, The TAGs corresponding to the synchronization resources in the second set of synchronization resources have valid TA values.

44. The device according to claim 43, wherein, The transceiver unit is also configured to perform at least one of the following: Initiate an LTM without a random access procedure to the first candidate cell; or If there are no synchronization resources in the second synchronization resource set whose L1 measurement results are greater than the third threshold, the second synchronization resource set is modified to include at least one of the following: all synchronization resources under the first candidate cell; all synchronization resources in the L1 measurement configuration associated with the first candidate cell; synchronization resources corresponding to the activated TCI state under the first candidate cell; and the first communication device reselects the second synchronization resource based on the L1 measurement results of the synchronization resource.

45. The device according to claim 39, wherein, The selection methods for the second synchronization resource include: Randomly select a synchronization resource from the second set of synchronization resources as the second synchronization resource.

46. ​​The device according to claim 45, wherein, The TAGs corresponding to the synchronization resources in the second set of synchronization resources have valid TA values.

47. The device according to claim 46, wherein, The transceiver unit is also used to initiate LTM (Local Time Transmission) without a random access procedure to the first candidate cell.

48. The device according to claim 43 or 46, wherein, The synchronization resources in the second set of synchronization resources have valid TA values ​​for their corresponding TAGs, including at least one of the following: The TAG ID corresponding to the synchronization resource in the second synchronization resource set is the same as the TAG ID corresponding to the TA value obtained in advance uplink synchronization; The first timer for the TAG ID corresponding to the synchronization resource in the second synchronization resource set is in running state.

49. A communication device, comprising: A transceiver, a processor, and a memory, wherein the memory is used to store a computer program, the transceiver is used to communicate with other devices, and the processor is used to invoke and run the computer program stored in the memory to cause the communication device to perform the method as described in any one of claims 1 to 49.

50. A chip, comprising: A processor for retrieving and running a computer program from memory, causing a device on which the chip is mounted to perform the method as described in any one of claims 1 to 24.

51. A computer-readable storage medium for storing a computer program that, when run by a device, causes the device to perform the method as described in any one of claims 1 to 24.

52. A computer program product comprising computer program instructions that cause a computer to perform the method as described in any one of claims 1 to 24.

53. A computer program that causes a computer to perform the method as described in any one of claims 1 to 24.

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