Communication method, system, user equipment and electronic device

Abstract

This disclosure relates to a communication method, system, user equipment, and electronic device, and pertains to the field of communication technology. The communication method, executed by the user equipment, includes: receiving first information transmitted by a base station, wherein the first information includes uplink timing adjustment information for one or more candidate cells; and performing a RACH-LESS handover process when the handover execution conditions of the first candidate cell are met and the first candidate cell has valid uplink timing adjustment information.

Description

Technical Field

[0001] This disclosure relates to the field of communication technology, and in particular to a communication method, system, user equipment, and electronic equipment. Background Technology

[0002] In L1 / L2 Triggered Mobility (LTM) handover mechanisms, the network side carries uplink timing adjustment information of candidate cells in the command instructing the terminal to perform cell handover. Summary of the Invention

[0003] One of the technical problems this disclosure aims to solve is: how to improve the performance of cell handover in scenarios where user equipment autonomously decides to hand over.

[0004] According to a first aspect of some embodiments of the present disclosure, a communication method is provided, executed by a user equipment, comprising: receiving first information sent by a base station, wherein the first information includes uplink timing adjustment information of one or more candidate cells; and performing a RACH-LESS handover process when the handover execution conditions of the first candidate cell are met and the first candidate cell has valid uplink timing adjustment information.

[0005] In some embodiments, the communication method further includes: sending second information to the base station before receiving the first information, wherein the second information is used to request early uplink synchronization.

[0006] In some embodiments, the second information includes any one of the following: indication information for instructing the user equipment to request early uplink synchronization; information on one or more candidate cells.

[0007] In some embodiments, the information of the candidate cell includes at least one of the following: the identifier of the candidate cell; one or more beam information associated with the candidate cell; the layer 3 measurement result of the candidate cell; and the layer 1 measurement result of the beam associated with the candidate cell.

[0008] In some embodiments, sending the second information to the base station includes: sending the second information to the base station in response to a specified condition being met.

[0009] In some embodiments, the specified conditions include at least one of the following: a first condition determined based on the handover execution conditions; and a second condition for triggering early uplink synchronization.

[0010] In some embodiments, the switching execution conditions include at least one of the execution conditions of Conditional Handover (CHO) and the execution conditions of Conditional LTM based on LTM configuration.

[0011] In some embodiments, the second condition includes the serving cell quality being lower than a first threshold and the candidate cell quality being higher than a second threshold.

[0012] In some embodiments, the second condition includes the serving cell having a beam quality lower than a third threshold and the candidate cell having a beam quality higher than a fourth threshold.

[0013] In some embodiments, the specified conditions further include at least one of the following: the user equipment is configured to request early uplink synchronization via second information; the number of times the user equipment requests early uplink synchronization via second information is less than a fifth threshold; the user equipment does not have any valid uplink timing adjustment information for any candidate cell or candidate cell group; and the first timer is not running.

[0014] In some embodiments, the communication method further includes: starting a first timer in response to sending second information to a base station; and stopping the first timer in response to receiving the first information.

[0015] In some embodiments, the second information is transmitted via Layer 1 signaling, Layer 2 signaling, or Radio Resource Control (RRC) signaling.

[0016] In some embodiments, the communication method further includes sending a measurement report to the base station before receiving the first information.

[0017] In some embodiments, one or more candidate cells belong to one or more candidate cell groups, and the uplink timing adjustment information of candidate cells in each candidate cell group is the same.

[0018] In some embodiments, the first candidate cell is a cell among one or more candidate cells, or a cell belonging to the same candidate cell group as a cell among one or more candidate cells.

[0019] In some embodiments, the communication method further includes: in response to receiving uplink timing adjustment information from one or more candidate cells, starting or restarting a second timer corresponding to each of the one or more candidate cells; and determining whether a first candidate cell has valid uplink timing adjustment information based on the second timer corresponding to the one or more candidate cells.

[0020] In some embodiments, determining whether the first candidate cell has valid uplink timing adjustment information includes: when the second timer corresponding to the first candidate cell is running and it is determined that the first candidate cell has valid uplink timing adjustment information; or when the second timer corresponding to the first candidate cell is not running or the running time exceeds a first specified time and it is determined that the first candidate cell does not have valid uplink timing adjustment information.

[0021] In some embodiments, one or more candidate cells belong to one or more candidate cell groups, and the uplink timing adjustment information of the candidate cell is the same as the uplink timing adjustment information of the candidate cell group to which the candidate cell belongs. The communication method further includes: in response to receiving uplink timing adjustment information of one or more candidate cell groups, starting or restarting a third timer corresponding to the candidate cell group for each candidate cell group in the one or more candidate cell groups; and determining whether the first candidate cell has valid uplink timing adjustment information based on the third timer corresponding to the one or more candidate cell groups.

[0022] In some embodiments, determining whether the first candidate cell has valid uplink timing adjustment information includes: determining that the first candidate cell has valid uplink timing adjustment information when the third timer corresponding to the first candidate cell is in running state; or determining that the first candidate cell does not have valid uplink timing adjustment information when the third timer corresponding to the first candidate cell is not in running state or the running time exceeds a second specified time.

[0023] In some embodiments, the communication method further includes: sending second information to the base station when the first candidate cell does not have valid uplink timing adjustment information and the specified conditions are met.

[0024] In some embodiments, the communication method further includes: receiving third information sent by the base station before receiving the first information; and performing advance uplink synchronization based on the third information.

[0025] In some embodiments, the third information includes at least one of the identifiers of one or more candidate cells and Physical Random Access Channel (PRACH) resources.

[0026] In some embodiments, the communication method further includes: after triggering the handover process, applying the uplink timing adjustment information of the first candidate cell to the primary timing advance group PTAG, and starting or restarting the fourth timer corresponding to the PTAG.

[0027] In some embodiments, the communication method further includes stopping the second timer corresponding to the first candidate cell.

[0028] In some embodiments, the communication method further includes: using the remaining runtime of the second timer corresponding to the first candidate cell as the runtime of the fourth timer; or using the remaining runtime of the third timer corresponding to the candidate cell group to which the first candidate cell belongs as the runtime of the fourth timer.

[0029] In some embodiments, the communication method further includes: after triggering the handover process, applying the uplink timing adjustment information of the first candidate cell to the PTAG; using the second timer corresponding to the first candidate cell as the fourth timer corresponding to the PTAG, or using the third timer corresponding to the candidate cell group to which the first candidate cell is located as the fourth timer corresponding to the PTAG.

[0030] In some embodiments, the communication method further includes: after triggering the handover process, applying the uplink timing adjustment information of the first candidate cell to the PTAG; continuing to run the second timer corresponding to the first candidate cell, or continuing to run the third timer corresponding to the candidate cell group to which the first candidate cell is located.

[0031] In some embodiments, the communication method further includes: performing uplink transmission of the serving cell within the PTAG during the operation of the second timer or the third timer.

[0032] In some embodiments, the communication method further includes: after triggering the handover process, stopping the second timer corresponding to other candidate cells besides the first candidate cell, or stopping the third timer corresponding to other candidate cell groups besides the candidate cell group to which the first candidate cell belongs.

[0033] In some embodiments, the communication method further includes: after triggering the handover process, deleting uplink timing adjustment information of other candidate cells or other candidate cell groups, except for the uplink timing adjustment information of the first candidate cell.

[0034] In some embodiments, the communication method further includes: after triggering the handover process, continuing to run a second timer corresponding to other candidate cells besides the first candidate cell, or continuing to run a third timer corresponding to other candidate cell groups besides the candidate cell group to which the first candidate cell belongs.

[0035] In some embodiments, the communication method further includes: determining, based on the indication information of the base station, whether to delete or retain uplink timing adjustment information of other candidate cells or other candidate cell groups, other than the uplink timing adjustment information of the first candidate cell, after switching to the first candidate cell.

[0036] According to a second aspect of some embodiments of the present disclosure, a user equipment is provided, comprising: a receiving module configured to receive first information sent by a base station, wherein the first information includes uplink timing adjustment information of one or more candidate cells; and an execution module configured to execute a RACH-LESS handover process when the handover execution conditions of the first candidate cell are met and the first candidate cell has valid uplink timing adjustment information.

[0037] According to a third aspect of some embodiments of this disclosure, a communication system is provided, including: a user equipment as described above; and a base station configured to send first information to the user equipment, wherein the first information includes uplink timing adjustment information for one or more candidate cells.

[0038] In some embodiments, the base station is further configured to receive second information sent by the user equipment before sending the first information, wherein the second information is used to request early uplink synchronization.

[0039] In some embodiments, the base station is further configured to receive a measurement report sent by the user equipment before sending the first information.

[0040] According to a fourth aspect of some embodiments of the present disclosure, an electronic device is provided, including: a processor; and a memory coupled to the processor for storing instructions that, when executed by the processor, cause the processor to perform the communication method as described above.

[0041] According to a fifth aspect of some embodiments of the present disclosure, a computer-readable storage medium is provided having a computer program stored thereon, wherein the program, when executed by a processor, implements the communication method as described above.

[0042] According to a sixth aspect of some embodiments of the present disclosure, a computer program product is provided, including instructions that, when executed by a processor, cause the processor to perform the communication method as described above.

[0043] This disclosure allows the user equipment to perform a RACH-LESS handover process when the handover execution conditions of the first candidate cell are met and the uplink timing adjustment information of the first candidate cell obtained from the base station is valid. This enables the user equipment to perform the RACH-LESS handover process in a timely manner according to the handover execution conditions, which not only reduces the latency of cell handover but also improves the reliability of cell handover, thus improving the performance of cell handover.

[0044] Other features and advantages of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 A flowchart illustrating a communication method according to some embodiments of the present disclosure is shown.

[0047] Figure 2 A flowchart illustrating a communication method according to other embodiments of the present disclosure is shown.

[0048] Figure 3 A flowchart illustrating a communication method according to other embodiments of the present disclosure is shown.

[0049] Figure 4 A flowchart illustrating a communication method according to other embodiments of the present disclosure is shown.

[0050] Figure 5 A schematic diagram of the structure of a user equipment according to some embodiments of the present disclosure is shown.

[0051] Figure 6 A schematic diagram of the structure of a base station according to some embodiments of the present disclosure is shown.

[0052] Figure 7 A schematic diagram of the structure of a communication system according to some embodiments of the present disclosure is shown.

[0053] Figure 8 A schematic diagram of the structure of an electronic device according to some embodiments of the present disclosure is shown.

[0054] Figure 9 A schematic diagram of the structure of an electronic device according to other embodiments of the present disclosure is shown. Detailed Implementation

[0055] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0056] With the development of high-speed mobile terminals such as high-speed rail, the robustness optimization of cell handover has become increasingly important. In high-speed mobile scenarios, the channel quality of the source cell monitored by the terminal deteriorates sharply. If the traditional handover mechanism is used, that is, the terminal sends the measurement report to the network side, and then the network side makes the decision and issues the handover command, it is easy to cause the handover to be too late, resulting in handover failure.

[0057] The CHO mechanism can alleviate the above problems. The CHO mechanism allows the terminal to decide to handover when the handover execution conditions are met. Since the terminal no longer triggers measurement reporting when the handover execution conditions are met, and the terminal has already obtained the configuration information in the handover command in advance, the CHO mechanism can improve the robustness of cell handover.

[0058] While CHO (Cross-Handed Handover) alleviates the problem of handover failure due to rapid channel quality degradation in high-speed mobile scenarios, it is triggered by Layer 3 (RRC) signaling, resulting in high handover latency. To further reduce handover latency, signaling overhead, and downtime, the LTM (Low-Temperature Handover) mechanism is proposed.

[0059] In the LTM handover mechanism, the terminal, such as the User Equipment (UE), performs Layer 1 measurements based on the candidate cell configuration information configured by the network side and periodically reports the Layer 1 measurement results. The network side determines whether to trigger a cell handover based on the Layer 1 measurement results reported by the UE and instructs the UE to perform the cell handover process via Layer 2 signaling (MACCE). Compared to handover triggered via RRC signaling, handover triggered via MACCE signaling has lower latency. Furthermore, to reduce handover latency, LTM handover allows the UE to send a random access preamble to the target cell in advance based on network-side instructions. The network side can then indicate uplink timing adjustment information via the MACCE signaling that triggers LTM handover, thus eliminating the need for the UE to obtain the uplink timing adjustment information of the target cell again through the random access procedure during the handover process, thereby reducing handover latency.

[0060] To further improve handover reliability while leveraging the low latency characteristics of the LTM mechanism, a conditional LTM mechanism is proposed. In the conditional LTM mechanism, the network side pre-configures decision events for the UE to evaluate and perform conditional LTM handover. When a candidate cell meets the execution conditions, the UE autonomously triggers the conditional LTM process.

[0061] Obtaining uplink timing adjustment information in advance is a key feature of LTM handover in reducing handover latency. In conventional LTM, the network can directly indicate the uplink timing adjustment information of the target cell via a handover command. However, in conditional LTM, the handover is triggered autonomously by the UE, without requiring the network to send a handover command. Therefore, it is necessary to investigate new methods for obtaining uplink timing adjustment information in advance to skip the process of the UE obtaining uplink synchronization through random access during conditional LTM handover, thereby reducing handover latency and improving handover performance and user experience.

[0062] In addition, a similar approach could be considered for the CHO mechanism, which would allow for the skipping of the random access process triggered during handover by obtaining uplink timing adjustment information in advance, thereby reducing handover latency and improving handover performance and user experience.

[0063] Based on this, the present disclosure provides a communication method. This communication method enables user equipment to perform a RACH-LESS handover process according to pre-configured handover execution conditions, reducing handover latency, improving handover reliability, and thus enhancing cell handover performance.

[0064] The communication method disclosed herein includes signaling interaction between user equipment and base station, which is described below from the user equipment side and the base station side respectively.

[0065] Figure 1 A flowchart illustrating a communication method according to some embodiments of the present disclosure is shown. Figure 1 As shown, the method of this embodiment includes steps S11 to S13, which are executed by the user equipment.

[0066] In step S11, the first information sent by the base station is received, wherein the first information includes uplink timing adjustment information of one or more candidate cells.

[0067] A candidate cell refers to a cell configured by the network side for user equipment to perform handover. The one or more candidate cells included in the first message can be some of the candidate cells configured by the network side for user equipment, or it can be all of the candidate cells configured by the network side for user equipment.

[0068] Considering that in actual deployments, multiple candidate cells may be located at the same base station or belong to the same frequency, the UE can share the same uplink timing adjustment information for these candidate cells. To reduce the frequency with which the UE obtains uplink timing adjustment information from candidate cells, conserve network-reserved PRACH resources, and reduce signaling interactions, the concept of candidate cell groups can be introduced. Candidate cells within the same candidate cell group share uplink timing adjustment information. Therefore, in some embodiments, one or more candidate cells in the first message belong to one or more candidate cell groups, and the uplink timing adjustment information is the same for candidate cells within each candidate cell group.

[0069] By setting up candidate cell groups, the UE only needs to perform an uplink synchronization process in advance for any candidate cell within the candidate cell group. After obtaining uplink timing adjustment information through the first message sent by the network side, the UE can associate this uplink timing adjustment information with any candidate cell within the candidate cell group. This reduces the number of times the UE needs to perform uplink synchronization in advance, saves UE power consumption, and reduces network resource reservation and signaling overhead. The network side can configure the candidate cell group corresponding to the candidate cell through RRC signaling.

[0070] The first message indicates uplink timing adjustment information for one or more candidate cells, or one or more candidate cell groups to which one or more candidate cells belong.

[0071] Uplink timing adjustment information is used to adjust the timing of uplink data transmission by the UE, so that the uplink signals of different UEs can be basically synchronized when they arrive at the base station, thereby avoiding interference between signals. In some embodiments, uplink timing adjustment information includes uplink timing advance (TA).

[0072] The base station provides first information to the user equipment (UE) so that the UE can autonomously execute the RACH-LESS handover process when it determines that the handover execution conditions are met. The triggering conditions for the base station to provide the first information to the UE can be triggered by the UE or by the base station itself, and the specific execution process will be described in detail later.

[0073] In step S13, if the handover execution conditions of the first candidate cell are met and the first candidate cell has valid uplink timing adjustment information, the handover process of skipping random access RACH-LESS is executed.

[0074] The first candidate cell is a cell among one or more candidate cells, or a cell that belongs to the same candidate cell group as one or more candidate cells.

[0075] The handover execution conditions for the first candidate cell refer to the execution conditions configured for the UE for handover to the first candidate cell through the RACH-LESS handover procedure. As described above, the communication method of this disclosure can be used for conditional LTM or CHO, therefore, the handover execution conditions include at least one of the execution conditions of conditional handover CHO and the execution conditions of conditional LTM based on LTM configuration.

[0076] When determining whether to execute a RACH-LESS handover procedure, in addition to meeting the handover execution conditions of the first candidate cell, valid uplink timing adjustment information of the first candidate cell is also required. This is because after the UE obtains the uplink timing adjustment information of the first candidate cell through the first information, it may not immediately execute the RACH-LESS handover procedure. For example, the handover execution conditions of the first candidate cell may not have been met when the first information is received.

[0077] Therefore, in order to determine the validity of the uplink timing adjustment information of the first candidate cell, it is necessary to maintain the uplink timing adjustment information in the first information.

[0078] In some embodiments, the communication method further includes: in response to receiving uplink timing adjustment information from one or more candidate cells, starting or restarting a second timer corresponding to each of the one or more candidate cells; and determining whether a first candidate cell has valid uplink timing adjustment information based on the second timer corresponding to the one or more candidate cells.

[0079] When the first information includes cell-level uplink timing adjustment information, that is, when the first information indicates uplink timing adjustment information of one or more candidate cells, a second timer is set for each candidate cell, and the validity of the uplink timing adjustment information of the candidate cell is determined by the state of the second timer.

[0080] For example, by setting a specified running time for the second timer corresponding to each candidate cell, if the second timer is not running or exceeds its specified time, the uplink timing adjustment information of the corresponding candidate cell is determined to be invalid. The length of the second timer (specified time) is configured by the network side through RRC signaling, and the length of the second timer corresponding to each candidate cell can be the same or different.

[0081] Since the first information indicates the uplink timing adjustment information of one or more candidate cells, meaning the first candidate cell is one of these candidate cells, we can first determine the second timer corresponding to the first candidate cell, and then determine whether the uplink timing adjustment information of the first candidate cell is valid based on the second timer corresponding to the first candidate cell.

[0082] In some embodiments, determining whether the first candidate cell has valid uplink timing adjustment information includes: when the second timer corresponding to the first candidate cell is running and it is determined that the first candidate cell has valid uplink timing adjustment information; or when the second timer corresponding to the first candidate cell is not running or the running time exceeds a first specified time and it is determined that the first candidate cell does not have valid uplink timing adjustment information.

[0083] Similar to the case where the first information includes cell-level uplink timing adjustment information, when the first information includes cell group-level uplink timing adjustment information, i.e., when the first information indicates uplink timing adjustment information for one or more candidate cell groups, a third timer is set for each candidate cell group, and the validity of the uplink timing adjustment information of the candidate cell group is determined by the state of the third timer.

[0084] That is, one or more candidate cells belong to one or more candidate cell groups, and the uplink timing adjustment information of the candidate cell is the same as the uplink timing adjustment information of the candidate cell group to which the candidate cell belongs. The above communication method further includes: in response to receiving uplink timing adjustment information of one or more candidate cell groups, starting or restarting a third timer corresponding to the candidate cell group for each candidate cell group in the one or more candidate cell groups; and determining whether the first candidate cell has valid uplink timing adjustment information according to the third timer corresponding to the one or more candidate cell groups.

[0085] The length of the third timer (specified time) is configured by the network side via RRC signaling. The length of the third timer for each candidate cell group can be the same or different.

[0086] Similarly, determining whether the first candidate cell has valid uplink timing adjustment information includes: determining that the first candidate cell has valid uplink timing adjustment information when the third timer corresponding to the first candidate cell is in operation; or determining that the first candidate cell does not have valid uplink timing adjustment information when the third timer corresponding to the first candidate cell is not in operation or the operation time exceeds the second specified time.

[0087] If the handover conditions for the first candidate cell are met and the first candidate cell has valid uplink timing adjustment information, the UE performs a RACH-LESS handover procedure. If the first candidate cell does not have valid uplink timing adjustment information, and if the uplink timing adjustment information for the first candidate cell can be reacquired, then the RACH-LESS handover procedure is performed after the uplink timing adjustment information for the first candidate cell is reacquired. Otherwise, a random access procedure needs to be initiated during the handover to the first candidate cell. The process of reacquiring the uplink timing adjustment information for the first candidate cell will be described in detail later.

[0088] The following describes how the base station sends the first message.

[0089] In some embodiments, the UE triggers the base station to send first information. That is, the above communication method further includes: sending second information to the base station before receiving the first information, wherein the second information is used to request early uplink synchronization. In other words, after receiving the second information sent by the UE, the base station sends the first information to the UE.

[0090] The second information is reported via Layer 1 signaling, such as through Channel State Information (CSI), adding an indication field requesting early uplink synchronization to the L1 measurement report used for LTM; or through Layer 2 signaling, such as using MAC CE reporting, adding an indication field requesting early uplink synchronization to the event-triggered L1 measurement report MAC CE; or through RRC signaling, such as sending using UE Assistance Information (UAI) messages. The second information includes any one of the following: indication information, used to instruct the user equipment to request early uplink synchronization; or information about one or more candidate cells.

[0091] The candidate cell information includes at least one of the following: the candidate cell's identifier (ID); one or more beam information associated with the candidate cell, such as the beam's reference signal index number: Synchronization Signal Block Index (SSB-index) or Channel State Information Reference Signal Index (CSI-RS Index); the candidate cell's layer 3 measurement results; and the candidate cell's layer 1 measurement results.

[0092] In this way, for one or more candidate cells, the UE sends a second message to the network side to request the triggering of early uplink synchronization. That is, the UE triggers the transmission of the first message by sending the second message. In some embodiments, sending the second message to the base station includes: sending the second message to the base station in response to the satisfaction of a specified condition.

[0093] The specified conditions include at least one of the following: a first condition determined based on the handover execution conditions; and a second condition used to trigger early uplink synchronization.

[0094] The first condition refers to the imminent fulfillment of the handover execution conditions by at least one candidate cell. That is, the UE sends the first information when it determines that the handover execution conditions are about to be met. The handover execution conditions include at least one of the execution conditions of the Call for Hazards (CHO) and the execution conditions of the Conditional LTM (Least Significant Term). Therefore, the first condition may include, for example, at least one of the execution conditions of the CHO by at least one candidate cell and at least one of the execution conditions of the Conditional LTM by at least one candidate beam. By using the already configured execution conditions of the CHO and Conditional LTM to assist the UE in its decision-making, the specific timing of the reporting can depend on the UE implementation, ensuring the flexibility of the UE implementation.

[0095] The second condition refers to strictly controlling the timing of the UE sending the first information by configuring a specific event. For example, in some embodiments, the second condition includes the serving cell quality being lower than a first threshold and the candidate cell quality being higher than a second threshold. In addition, the second condition may also include the serving cell quality being lower than the candidate cell quality by a first offset.

[0096] In some embodiments, the second condition includes the serving cell's beam quality being lower than a third threshold and the candidate cell's beam quality being higher than a fourth threshold. Additionally, the second condition may also include the serving cell's beam quality being lower than the candidate cell's beam quality by a second offset.

[0097] By adjusting the first threshold, second threshold, third threshold, and fourth threshold, the timing of the UE sending the first information can be strictly controlled, reducing the differences in handover performance caused by different UE algorithms from different manufacturers.

[0098] In addition to the first and second conditions, the specified conditions may also include restrictive conditions. That is, the specified conditions may also include at least one of the following: a third condition, the user equipment is configured to request early uplink synchronization via the second information; a fourth condition, the number of times the user equipment requests early uplink synchronization via the second information is less than a fifth threshold; a fifth condition, the user equipment does not have any valid uplink timing adjustment information for any candidate cell or candidate cell group; and a sixth condition, the first timer is not running.

[0099] The third condition instructs the UE to trigger the base station to send the first information based on sending the second information. This function is controlled by the network side. The network side can flexibly configure whether to support early uplink synchronization based on UE requests according to implementation or load, so as to ensure the overall network performance and avoid problems such as network performance degradation and insufficient Random Access Channel (RACH) resources caused by a large number of UEs requesting early synchronization at the same time.

[0100] The fourth condition indicates that the network side can configure the maximum number of times the UE sends the first information request to trigger early uplink synchronization, avoiding problems such as insufficient PRACH resources or increased signaling overhead caused by frequent UE requests for early uplink synchronization. The network side can configure the total maximum number of first information triggers, or configure an independent maximum number for each candidate cell or candidate cell group.

[0101] The fifth condition states that, to reduce issues such as insufficient PRACH resources or increased signaling overhead caused by frequent UE requests for early uplink synchronization, the network can be configured so that when the UE has already saved valid uplink timing adjustment information for other candidate cells or candidate cell groups, the UE will not send a second message to trigger new early uplink synchronization. This reduces handover latency while saving network reserved resources and improving resource utilization. Only when the uplink timing adjustment information for other candidate cells or candidate cell groups becomes invalid can the UE request early uplink synchronization by sending a second message.

[0102] The sixth condition considers that the early uplink synchronization process requires interaction between the UE and candidate cells, and between the candidate cells (base stations) and the source base station, which requires a certain processing delay. Therefore, a timer mechanism can be introduced. After the UE sends the second information request to trigger early uplink synchronization, it starts the first timer. During the operation of the first timer, if a new candidate cell or candidate cell group meets the specified conditions for sending the second information, the UE will not send the second information again. The UE can only send the second information again to request triggering a new early uplink synchronization when the first timer expires, stops, or is no longer running. Furthermore, the UE can stop the first timer after receiving the second information sent by the network side.

[0103] That is, the above communication method further includes: starting a first timer in response to sending second information to the base station; and stopping the first timer in response to receiving the first information.

[0104] The aforementioned multiple binding conditions, along with the first and second conditions, can be combined according to the actual situation to form the specified conditions for sending the second information. That is, the specified conditions include at least one of the first and second conditions, and at least one of the third, fourth, fifth, and sixth conditions.

[0105] After the UE sends the second information to the base station, the base station, based on the UE's request, determines whether to trigger early uplink synchronization and identifies candidate cells requiring early uplink synchronization, PRACH resources used for early uplink synchronization, and related configuration information. The network side, based on the candidate cells or candidate cell beam list reported by the UE and related measurement results, combined with network load, determines the candidate cells and / or candidate cell beams suitable for early uplink synchronization and sends the third information to the UE. The candidate cells and / or candidate cell beams indicated by the base station in the third information may be the same as or different from the candidate cells and / or candidate cell beams requested by the UE. The UE performs early uplink synchronization based on the third information, triggering the base station to subsequently send the first information to the UE.

[0106] The above embodiments describe a method for triggering early uplink synchronization based on UE requests. This method can assist the network side in triggering early uplink synchronization more accurately, avoiding problems such as handover failure or invalidation of uplink timing adjustment information due to triggering uplink synchronization too late or too early. However, it also increases the complexity of the interaction between the UE and the base station. Therefore, another approach is to trigger the early uplink synchronization process from the network side to reduce signaling interaction between the UE and the network. Of course, in actual deployment, a combination of these two approaches can also be considered.

[0107] When the UE is triggered to perform early uplink synchronization via the network side, the UE sends a measurement report to the base station before receiving the first information. The measurement report includes measurement report messages reported by the UE via RRC signaling, L1 measurement reports sent via UCI, or measurement reports reported via MACCE. Subsequently, based on the measurement reports routinely reported by the UE, if the network side predicts that the handover execution conditions are about to be met (e.g., the UE is about to perform a conditional LTM or CHO handover), it sends a third message to the UE, instructing the UE to perform early uplink synchronization. The UE performs early uplink synchronization based on the third message, triggering the base station to subsequently send the first information to the UE.

[0108] In other words, the above communication method also includes: receiving third information sent by the base station before receiving the first information; and performing early uplink synchronization based on the third information. The third information includes at least one of the identifiers of one or more candidate cells and PRACH resources. That is, the UE performs PRACH transmission and early uplink synchronization based on the third information.

[0109] The above embodiments describe the transmission of first information triggered by the UE or the network side. Furthermore, as described above, if the uplink timing adjustment information of the first candidate cell is invalid, and if the uplink timing adjustment information of the first candidate cell can be reacquired, then the RCAH-LESS handover process is performed based on the reacquired uplink timing adjustment information of the first candidate cell.

[0110] Therefore, when the transmission of the first information is triggered by the UE, the above communication method further includes: sending the second information to the base station when the first candidate cell does not have valid uplink timing adjustment information and the specified conditions are met. In this way, when the specified conditions are met, the UE can reacquire the first information by sending the second information to the base station, thereby realizing the execution of the RCAH-LESS handover process.

[0111] If the first information is sent based on the network side, and the network side predicts again that the handover execution conditions will be met based on the measurement report sent by the UE, the second information will be sent to the UE again.

[0112] Therefore, regardless of whether the first information is triggered by the UE or by the network, it can provide a supplementary solution for the failure of the uplink timing adjustment information of the first candidate cell, so as to enable the UE to successfully execute the handover process of RCAH-LESS, thereby reducing handover latency and improving handover reliability.

[0113] In the above embodiments, when the user equipment determines that the handover execution conditions of the first candidate cell are met and the uplink timing adjustment information of the first candidate cell obtained from the base station is valid, the user equipment performs the RACH-LESS handover process. This enables the user equipment to perform the RACH-LESS handover process in a timely manner according to the handover execution conditions. This not only reduces the latency of cell handover but also improves the reliability of cell handover, thus improving the performance of cell handover.

[0114] Furthermore, in the conventional LTM mechanism, after receiving a handover command from the network, the UE applies the uplink timing adjustment information included in the handover command, or the uplink timing adjustment information measured autonomously by the UE, to the Primary Timing Advance Group (PTAG), and starts or restarts the timer corresponding to the PTAG to maintain the UE's uplink synchronization state. However, in the application scenario disclosed in this disclosure, i.e., the scenario where the UE autonomously decides to handover, it is also necessary to consider how the UE configures or processes the timer corresponding to the PTAG to enable the UE to transmit uplink normally.

[0115] In some embodiments, the above communication method further includes: after triggering the handover process, applying the uplink timing adjustment information of the first candidate cell to the PTAG, and starting or restarting the fourth timer corresponding to the PTAG.

[0116] That is, after applying the uplink timing adjustment information of the first candidate cell to the PTAG, or in response to applying the uplink timing adjustment information of the first candidate cell to the PTAG, the fourth timer corresponding to the PTAG is started or restarted. The uplink synchronization state of the UE with the serving cell within the PTAG is maintained by starting or restarting the fourth timer corresponding to the PTAG.

[0117] Since the uplink timing adjustment information of the first candidate cell is valid for a certain period of time—that is, as long as the running time of the second timer corresponding to the first candidate cell does not exceed a first specified time, or the running time of the third timer corresponding to the candidate cell group to which the first candidate cell belongs does not exceed a second specified time—the uplink timing adjustment information of the first candidate cell is valid. Therefore, after applying the uplink timing adjustment information of the first candidate cell to the PTAG, the running time of the fourth timer that is started or restarted should be set to the remaining running time of the second timer corresponding to the first candidate cell, or the remaining running time of the third timer corresponding to the candidate cell group to which the first candidate cell belongs.

[0118] In some embodiments, the communication method further includes: using the remaining runtime of the second timer corresponding to the first candidate cell as the runtime of the fourth timer; or using the remaining runtime of the third timer corresponding to the candidate cell group to which the first candidate cell belongs as the runtime of the fourth timer.

[0119] In some embodiments, the communication method further includes stopping the second timer corresponding to the first candidate cell. That is, after applying the uplink timing adjustment information of the first candidate cell to the PTAG, uplink timing adjustment information is no longer maintained for the first candidate cell itself.

[0120] In some embodiments, if the first candidate cell belongs to a candidate cell group, the third timer corresponding to the candidate cell group to which the first candidate cell belongs is not stopped. This also allows for the maintenance of uplink timing adjustment information for other candidate cells within the candidate cell group to which the first candidate cell belongs, for possible application scenarios, such as re-executing the handover process.

[0121] In some embodiments, the communication method further includes: after triggering the handover process, applying the uplink timing adjustment information of the first candidate cell to the PTAG; using the second timer corresponding to the first candidate cell as the fourth timer corresponding to the PTAG, or using the third timer corresponding to the candidate cell group to which the first candidate cell is located as the fourth timer corresponding to the PTAG.

[0122] That is, after applying the uplink timing adjustment information of the first candidate cell to the PTAG, the second timer corresponding to the first candidate cell, or the second timer corresponding to the first candidate cell, is used as the fourth timer corresponding to the PTAG. In this way, there is no need to introduce a new timer. The maintenance of the uplink timing adjustment information of the serving cell in the PTAG can be achieved through the existing timer, making the overall process simpler.

[0123] In some embodiments, the communication method further includes: after triggering the handover process, applying the uplink timing adjustment information of the first candidate cell to the PTAG; continuing to run the second timer corresponding to the first candidate cell, or continuing to run the third timer corresponding to the candidate cell group to which the first candidate cell is located.

[0124] In other words, after applying the uplink timing adjustment information of the first candidate cell to the PTAG, the PTAG is no longer associated with a timer; that is, the fourth timer associated with the PTAG is not started or restarted. Furthermore, during the operation of the second timer corresponding to the first candidate cell, or during the operation of the third timer corresponding to the candidate cell group to which the first candidate cell belongs, the PTAG is determined to be in an uplink synchronization state, enabling the UE to perform normal uplink transmission. That is, the above communication method also includes: performing uplink transmission of the serving cell within the PTAG during the operation of the second or third timer. In this way, the maintenance of the uplink timing adjustment information of the serving cell within the PTAG can be achieved using the existing timers themselves, without needing to associate a timer with the PTAG, further improving the simplicity of the overall process.

[0125] In the above embodiments, after applying the uplink timing adjustment information of the first candidate cell to the PTAG, a fourth timer can be started or restarted for the PTAG, or the original timer corresponding to the first candidate cell can be used as the timer for the PTAG, or the timer can be not associated with the PTAG, and the original timer corresponding to the first candidate cell can be used directly to maintain the uplink synchronization state of the PTAG. These methods can be deployed individually or in combination according to the actual situation.

[0126] In some embodiments, after the UE triggers the handover process to the first candidate cell, how the UE processes or maintains the uplink timing adjustment information of candidate cells other than the first candidate cell, or candidate cell groups other than the group to which the first candidate cell belongs, so as to make full use of or organize this information.

[0127] In some embodiments, the communication method further includes: after triggering the handover process, stopping the second timer corresponding to other candidate cells besides the first candidate cell, or stopping the third timer corresponding to other candidate cell groups besides the candidate cell group to which the first candidate cell is located.

[0128] That is, after the UE triggers the handover process to the first candidate cell, the timer corresponding to the first candidate cell is stopped. In other words, after the UE undergoes the handover process to the first candidate cell, the uplink timing adjustment information it obtained in advance in the source cell becomes invalid.

[0129] In some embodiments, the communication method further includes: after triggering the handover process, deleting uplink timing adjustment information of other candidate cells or other candidate cell groups, except for the uplink timing adjustment information of the first candidate cell.

[0130] That is, after the handover process is triggered, the uplink timing adjustment information of other candidate cells, except for the uplink timing adjustment information of the first candidate cell, is deleted; or, the uplink timing adjustment information of other candidate cell groups, except for the uplink timing adjustment information of the group to which the first candidate cell belongs, is deleted.

[0131] In some embodiments, after the UE triggers the handover process to the first candidate cell, while stopping the timer corresponding to the first candidate cell, the uplink timing adjustment information of other candidate cells or other candidate cell groups, except for the uplink timing adjustment information of the first candidate cell, is deleted.

[0132] In some embodiments, the communication method further includes: after triggering the handover process, continuing to run a second timer corresponding to other candidate cells besides the first candidate cell, or continuing to run a third timer corresponding to other candidate cell groups besides the candidate cell group to which the first candidate cell belongs.

[0133] That is, after a UE undergoes a handover process to the first candidate cell, the uplink timing adjustment information it acquired in advance in the source cell remains valid. This information can be used for potential handover processes, reducing the need for subsequent information acquisition.

[0134] In some embodiments, the communication method further includes: determining, based on the indication information of the base station, whether to delete or retain uplink timing adjustment information of other candidate cells or other candidate cell groups, excluding the uplink timing adjustment information of the first candidate cell, after switching to the first candidate cell.

[0135] In some embodiments, the communication method further includes: determining, based on the indication information from the base station, whether to continue running a second timer corresponding to other candidate cells besides the first candidate cell, or whether to continue running a third timer corresponding to other candidate cell groups besides the candidate cell group to which the first candidate cell belongs, after switching to the first candidate cell.

[0136] In some embodiments, based on the indication information from the base station, after switching to the first candidate cell, it is determined whether to delete or retain the uplink timing adjustment information of other candidate cells or other candidate cell groups other than the uplink timing adjustment information of the first candidate cell, and at the same time, it is determined whether to continue running the second timer corresponding to other candidate cells other than the first candidate cell, or the third timer corresponding to other candidate cell groups other than the candidate cell group to which the first candidate cell belongs.

[0137] In other words, the UE can determine, based on the network-side indications, whether to continue maintaining the validity of uplink timing adjustment information of other candidate cells or candidate cell groups acquired in advance under the source cell, and whether to delete or retain the uplink timing adjustment information of other candidate cells or candidate cell groups acquired in advance under the source cell. The network side can allocate configuration indications for each candidate cell or candidate cell group, allowing the network side to configure different operating methods based on information such as the deployment of candidate cells or candidate cell groups, thus improving the flexibility of information management. Alternatively, the network side can configure indications for all candidate cells or all candidate cell groups as a whole, using a single indication to manage the uplink timing adjustment information of all candidate cells or all candidate cell groups. This simplifies management and helps reduce the complexity of the UE.

[0138] In the above embodiments, after the UE performs the handover process to the first candidate cell, it can directly determine whether to continue maintaining the uplink timing adjustment information of other candidate cells or candidate cell groups that it acquired in advance under the source cell, or it can determine whether to continue maintaining the uplink timing adjustment information of other candidate cells or candidate cell groups that it acquired in advance under the source cell according to the base station's instruction. This provides the UE with multiple ways to process the uplink timing adjustment information of other candidate cells or candidate cell groups that it acquired in advance under the source cell, which can enhance the applicability of various scenarios.

[0139] The communication method of this disclosure is described below based on the base station side. Figure 2 A flowchart illustrating a communication method according to other embodiments of this disclosure is shown. For example... Figure 2 As shown, the communication method of this embodiment includes step S21, which is executed by the base station.

[0140] In step S21, first information is sent to the user equipment, wherein the first information includes uplink timing adjustment information for one or more candidate cells.

[0141] As mentioned above, the base station can send the first message triggered by the UE. Therefore, the communication method further includes: receiving a second message sent by the user equipment before sending the first message, wherein the second message is used to request early uplink synchronization.

[0142] The base station may send the first information if it predicts that the handover conditions will be met. Therefore, the communication method may also include receiving a measurement report sent by the user equipment before sending the first information.

[0143] The signaling interaction between the UE and the base station has been described in detail when the communication method of this disclosure is described from the UE side, and will not be repeated here.

[0144] In existing LTM mechanisms, the network side uses the LTM cell handover MAC CE to indicate the uplink timing adjustment information of candidate cells. However, in conditional LTM mechanisms, the UE initiates the handover autonomously, and the network side does not need to send the original LTM cell handover MAC CE. Therefore, the UE cannot obtain the uplink timing adjustment information of candidate cells in advance according to the existing mechanism. Furthermore, the existing CHO mechanism does not support obtaining uplink timing adjustment information in advance and cannot skip the random access process during handover, resulting in additional handover latency. This disclosure proposes a new communication method for obtaining uplink timing adjustment information in advance. This communication method is applicable not only to conditional LTM and CHO mechanisms but also to other scenarios where the handover is initiated autonomously by the UE.

[0145] Furthermore, in scenarios where handover is triggered autonomously by the UE, the network cannot accurately predict the timing of the handover, which may lead to the failure of uplink timing adjustment information and thus handover failure. Therefore, the communication method disclosed herein also includes a method for determining the validity of uplink timing adjustment information, i.e., a method for maintaining the validity of uplink timing adjustment information is proposed. This reduces the occurrence of handover failures due to the failure of uplink timing adjustment information, thereby improving the handover success rate and reducing service interruptions.

[0146] Furthermore, this disclosure considers how to maintain the uplink synchronization state of the PTAG after triggering the handover process to the first candidate cell, and how to handle uplink timing adjustment information of other candidate cells or other candidate cell groups obtained by the UE in the source cell. This disclosure provides multiple processing methods, which can enhance the applicability of the scenario and provide multiple implementation schemes for the UE to perform normal uplink transmission.

[0147] Figure 3 A flowchart illustrating a communication method according to other embodiments of this disclosure is shown. For example... Figure 3 As shown, the method of this embodiment includes steps S31 to S315.

[0148] In step S31, the (source) base station determines to configure condition LTM or CHO based on the measurement report reported by the UE, that is, sends an RRC reconfiguration message to the UE, which includes configuration information related to condition LTM or CHO, configuration to support early uplink synchronization triggered based on UE request, and configuration of conditions for the UE to determine to trigger early uplink synchronization, that is, the specified conditions for sending the second information mentioned above.

[0149] In step S32, the UE evaluates whether specified conditions are met according to the base station configuration. For example, it evaluates whether a candidate cell or its beam is about to switch specified conditions, or whether at least one candidate cell or its beam meets at least one of the conditions for triggering an early uplink synchronization request. Specified conditions may also include the binding conditions described above. If the specified conditions are met, second information is determined, including information about the candidate cell or its beam, to trigger the early uplink synchronization request.

[0150] In step S33, the UE sends a second message to the base station, requesting the base station to trigger early uplink synchronization, and simultaneously indicates candidate cells (in this embodiment, the second message indicates candidate cell 1 and candidate cell 2), candidate beams, and related measurement results. Furthermore, in response to sending the second message, the UE starts a first timer. During the operation of the first timer, the UE cannot send the second message again to request early uplink synchronization.

[0151] In step S34, the base station decides to trigger early uplink synchronization based on the UE's request and determines candidate cell 1.

[0152] In step S35, the base station sends third information to the UE, indicating the candidate cell for early uplink synchronization (in this embodiment, the third information indicates candidate cell 1) and RACH resources and related configurations, triggering the UE to perform early uplink synchronization.

[0153] In step S36, the UE sends a PRACH to candidate cell 1 according to the base station's instruction to assist candidate cell 1 in determining uplink timing adjustment information.

[0154] In step S37, candidate cell 1 determines the uplink timing adjustment information and sends it to the source base station. The source base station sends first information to the UE, indicating the timing adjustment information of candidate cell 1.

[0155] In step S38, the UE obtains the uplink timing adjustment information of candidate cell 1 based on the first information and starts the second timer corresponding to candidate cell 1. During the operation of the second timer, the UE considers the uplink timing adjustment information of candidate cell 1 to be valid.

[0156] In step S39, the second timer of candidate cell 1 times out. The UE determines that the conditions for sending the second information to request early uplink synchronization are met, and sends the second information to the base station, requesting the base station to trigger early uplink synchronization. At the same time, it indicates the candidate cells (in this embodiment, the second information indicates candidate cell 1 and candidate cell 3), candidate beams, and related measurement results. The UE starts the first timer. During the operation of the first timer, the UE cannot send the first message again to request early uplink synchronization.

[0157] In step S310, the base station, based on the UE's request, decides to trigger early uplink synchronization and determines candidate cell 1. The determination of candidate cell 1 here is merely exemplary; it could also be candidate cell 2 or candidate cell 3. For example, if candidate cell 2 is determined, the information related to candidate cell 1 in steps S311-S315 will be changed to the corresponding information for candidate cell 2.

[0158] In step S311, the base station sends third information to the UE, indicating candidate cell 1 for early uplink synchronization, RACH resources and related configurations, triggering the UE to perform early uplink synchronization.

[0159] In step S312, the UE sends a PRACH to candidate cell 1 according to the base station instruction to assist candidate cell 1 in determining uplink timing adjustment information.

[0160] In step S313, candidate cell 1 determines the uplink timing adjustment information and sends it to the source base station. The source base station sends first information to the UE, indicating the timing adjustment information of candidate cell 1.

[0161] In step S314, the UE obtains the uplink timing adjustment information of candidate cell 1 based on the first information and starts the second timer corresponding to candidate cell 1. During the operation of the second timer, the UE evaluates that candidate cell 1 meets the handover execution conditions and considers the uplink timing adjustment information of candidate cell 1 to be valid.

[0162] In step S315, the UE skips random access and performs a RACH-less handover procedure to candidate cell 1.

[0163] The above embodiments describe a UE-triggered early uplink synchronization process and enable the UE to perform RCAH-LESS handover. In this embodiment, the early uplink synchronization process can be controlled by configuring the specified conditions for sending the second information by the UE, thereby enabling the UE to perform the RCAH-LESS handover process in a timely and reliable manner.

[0164] Figure 4 A flowchart illustrating a communication method according to other embodiments of this disclosure is shown. For example... Figure 4As shown, the method of this embodiment includes steps S41 to S49.

[0165] In step S41, the (source) base station determines whether to configure conditional LTM or CHO handover based on the measurement report reported by the UE, and sends an RRC reconfiguration message to the UE, which includes the relevant configuration information for conditional LTM or CHO, as well as the candidate cell group configuration. Candidate cells within the candidate cell group share uplink timing adjustment information.

[0166] In step S42, the UE assesses whether the handover execution conditions are met based on the base station configuration. Simultaneously, it reports a standard L1 or L3 measurement report according to the measurement configuration.

[0167] In step S43, the network side predicts that the UE will soon experience a conditional LTM or CHO based on the measurement reports regularly reported by the UE, and determines possible candidate cells 1.

[0168] In step S44, the base station sends third information to the UE, indicating candidate cell 1 for early uplink synchronization, PRACH resources and related configurations, triggering the UE to perform early uplink synchronization.

[0169] In step S45, the UE sends a PRACH to candidate cell 1 according to the base station instruction to assist candidate cell 1 in determining uplink timing adjustment information.

[0170] In step S46, candidate cell 1 determines the uplink timing adjustment information and sends it to the source base station. The source base station sends first information to the UE, indicating the uplink timing adjustment information of candidate cell 1.

[0171] In step S47, the UE obtains the uplink timing adjustment information of candidate cell 1 based on the first information and starts the third timer of candidate cell group 1 corresponding to candidate cell 1. During the operation of the third timer, the UE considers the uplink timing adjustment information of any candidate cell in candidate cell group 1 to be valid and shares the uplink timing adjustment information of candidate cell 1.

[0172] In step S48, the UE determines that candidate cell 2 meets the handover execution conditions and that candidate cell 2 belongs to candidate cell group 1, and the corresponding third timer is in running state. Then the UE considers the uplink timing adjustment information of candidate cell 2 to be valid.

[0173] In step S49, the UE skips random access and performs a RACH-LESS handover procedure to candidate cell 2.

[0174] The above embodiments describe a base station-triggered early uplink synchronization process and the handover process for UE to perform RCAH-LESS. In this embodiment, the base station predicts that the UE will perform conditional LTM or CHO to assist the UE in performing the early uplink synchronization process. The signaling interaction between the base station and the UE is relatively simple, reducing the implementation complexity of the UE's RCAH-LESS handover process.

[0175] It should be noted that, Figure 3 The diagram illustrates a UE-triggered early uplink synchronization process, whereby the UE sends a second message to the base station, triggering the base station to send a first message to the UE. This first message includes cell-level uplink timing adjustment information. The cell-level uplink timing adjustment information included in the first message is merely exemplary; it could also include cell group-level uplink timing adjustment information. In other words, the first message could indicate the uplink timing adjustment information for the cell group to which candidate cell 1 belongs. If this uplink timing adjustment information is valid, the UE can subsequently perform a RACH-LESS handover procedure to other candidate cells within the cell group to which candidate cell 1 belongs.

[0176] Similarly, Figure 4 The base station predicts that the handover conditions will be met, meaning that the base station predicts the UE will execute condition LTM or CHO, and then sends first information to the UE. The first information includes cell group-level uplink timing adjustment information. The cell group-level uplink timing adjustment information included in the first information is merely exemplary; the first information could also include cell-level uplink timing adjustment information. That is, the first information could indicate the uplink timing adjustment information for candidate cell 1. Candidate cell 1 does not belong to any candidate cell group. If this uplink timing adjustment information is valid, the UE will still subsequently perform a RACH-LESS handover procedure based on candidate cell 1.

[0177] Figure 5 A schematic diagram of the structure of a user equipment according to some embodiments of the present disclosure is shown. For example... Figure 5 As shown, user equipment 5 includes:

[0178] The receiving module 51 is configured to receive first information sent by the base station, wherein the first information includes uplink timing adjustment information of one or more candidate cells;

[0179] The execution module 52 is configured to perform a RACH-LESS handover process when the handover execution conditions of the first candidate cell are met and the first candidate cell has valid uplink timing adjustment information.

[0180] In some embodiments, the user equipment 5 is further configured to send a second message to the base station before receiving the first message, wherein the second message is used to request early uplink synchronization.

[0181] In some embodiments, the second information includes any one of the following: indication information for instructing the user equipment to request early uplink synchronization; information on one or more candidate cells.

[0182] In some embodiments, the information of the candidate cell includes at least one of the following: the identifier of the candidate cell; one or more beam information associated with the candidate cell; the layer 3 measurement result of the candidate cell; and the layer 1 measurement result of the beam associated with the candidate cell.

[0183] In some embodiments, the user equipment 5 is further configured to send second information to the base station in response to a specified condition being met.

[0184] In some embodiments, the specified conditions include at least one of the following: a first condition determined based on the handover execution conditions; and a second condition for triggering early uplink synchronization.

[0185] In some embodiments, switching execution conditions includes at least one of the execution conditions of CHO and the execution conditions of LTM-based configuration conditions.

[0186] In some embodiments, the second condition includes the serving cell quality being lower than a first threshold and the candidate cell quality being higher than a second threshold.

[0187] In some embodiments, the second condition includes the serving cell having a beam quality lower than a third threshold and the candidate cell having a beam quality higher than a fourth threshold.

[0188] In some embodiments, the specified conditions further include at least one of the following: the user equipment is configured to request early uplink synchronization via second information; the number of times the user equipment requests early uplink synchronization via second information is less than a fifth threshold; the user equipment does not have any valid uplink timing adjustment information for any candidate cell or candidate cell group; and the first timer is not running.

[0189] In some embodiments, the user equipment 5 is further configured to start a first timer in response to sending second information to the base station, and to stop the first timer in response to receiving the first information.

[0190] In some embodiments, the second information is sent via Layer 1 signaling, Layer 2 signaling, or RRC signaling.

[0191] In some embodiments, the user equipment 5 is further configured to send a measurement report to the base station before receiving the first information.

[0192] In some embodiments, one or more candidate cells belong to one or more candidate cell groups, and the uplink timing adjustment information of candidate cells in each candidate cell group is the same.

[0193] In some embodiments, the first candidate cell is a cell among one or more candidate cells, or a cell belonging to the same candidate cell group as a cell among one or more candidate cells.

[0194] In some embodiments, the user equipment 5 is further configured to, in response to receiving uplink timing adjustment information from one or more candidate cells, start or restart a second timer corresponding to each of the one or more candidate cells; and determine whether the first candidate cell has valid uplink timing adjustment information based on the second timer corresponding to the one or more candidate cells.

[0195] In some embodiments, the user equipment 5 is further configured to determine that the first candidate cell has valid uplink timing adjustment information when the second timer corresponding to the first candidate cell is running; or to determine that the first candidate cell does not have valid uplink timing adjustment information when the second timer corresponding to the first candidate cell is not running or the running time exceeds a first specified time.

[0196] In some embodiments, one or more candidate cells belong to one or more candidate cell groups, and the uplink timing adjustment information of the candidate cell is the same as the uplink timing adjustment information of the candidate cell group to which the candidate cell belongs. The user equipment 5 is further configured to, in response to receiving the uplink timing adjustment information of one or more candidate cell groups, start or restart a third timer corresponding to the candidate cell group for each candidate cell group in the one or more candidate cell groups; and determine whether the first candidate cell has valid uplink timing adjustment information based on the third timer corresponding to the one or more candidate cell groups.

[0197] In some embodiments, the user equipment 5 is further configured to determine that the first candidate cell has valid uplink timing adjustment information when the third timer corresponding to the first candidate cell is in running state; or to determine that the first candidate cell does not have valid uplink timing adjustment information when the third timer corresponding to the first candidate cell is not in running state or the running time exceeds a second specified time.

[0198] In some embodiments, the user equipment 5 is further configured to send second information to the base station if the first candidate cell does not have valid uplink timing adjustment information and a specified condition is met.

[0199] In some embodiments, the user equipment 5 is further configured to receive third information sent by the base station before receiving the first information; and to perform advance uplink synchronization based on the third information.

[0200] In some embodiments, the third information includes the identifiers of one or more candidate cells and at least one of the PRACH resources.

[0201] In some embodiments, the user equipment 5 is further configured to apply the uplink timing adjustment information of the first candidate cell to the primary timing advance group PTAG after triggering the handover process, and to start or restart the fourth timer corresponding to the PTAG.

[0202] In some embodiments, user equipment 5 is further configured to stop the second timer corresponding to the first candidate cell.

[0203] In some embodiments, the user equipment 5 is further configured to use the remaining duration of the second timer corresponding to the first candidate cell as the runtime of the fourth timer; or to use the remaining duration of the third timer corresponding to the candidate cell group to which the first candidate cell belongs as the runtime of the fourth timer.

[0204] In some embodiments, the user equipment 5 is further configured to apply the uplink timing adjustment information of the first candidate cell to the PTAG after triggering the handover process; and to use the second timer corresponding to the first candidate cell as the fourth timer corresponding to the PTAG, or to use the third timer corresponding to the candidate cell group to which the first candidate cell is located as the fourth timer corresponding to the PTAG.

[0205] In some embodiments, the user equipment 5 is further configured to apply the uplink timing adjustment information of the first candidate cell to the PTAG after triggering the handover process; continue to run the second timer corresponding to the first candidate cell, or continue to run the third timer corresponding to the candidate cell group to which the first candidate cell is located.

[0206] In some embodiments, user equipment 5 is also configured to perform uplink transmission of the serving cell within the PTAG during the operation of a second or third timer.

[0207] In some embodiments, the user equipment 5 is further configured to, after triggering the handover process, stop the second timer corresponding to other candidate cells besides the first candidate cell, or stop the third timer corresponding to other candidate cell groups besides the candidate cell group to which the first candidate cell belongs.

[0208] In some embodiments, the user equipment 5 is further configured to delete uplink timing adjustment information of other candidate cells or other candidate cell groups, except for the uplink timing adjustment information of the first candidate cell, after triggering the handover process.

[0209] In some embodiments, the user equipment 5 is further configured to continue running a second timer corresponding to other candidate cells besides the first candidate cell after the handover process is triggered, or to continue running a third timer corresponding to other candidate cell groups besides the candidate cell group to which the first candidate cell belongs.

[0210] In some embodiments, the user equipment 5 is further configured to determine, based on the indication information from the base station, whether to delete or retain uplink timing adjustment information of other candidate cells or other candidate cell groups, other than the uplink timing adjustment information of the first candidate cell, after switching to the first candidate cell.

[0211] When the handover execution conditions of the first candidate cell are met and the uplink timing adjustment information of the first candidate cell obtained from the base station is valid, the user equipment performs the RACH-LESS handover process. This enables the user equipment to perform the RACH-LESS handover process in a timely manner according to the handover execution conditions. This not only reduces the latency of cell handover but also improves the reliability of cell handover, thus improving the performance of cell handover.

[0212] Figure 6 A schematic diagram of the structure of a base station according to some embodiments of the present disclosure is shown. For example... Figure 6 As shown, base station 6 includes: a transmitting module 61, configured to transmit first information to user equipment, wherein the first information includes uplink timing adjustment information of one or more candidate cells.

[0213] In some embodiments, the base station 6 is further configured to receive second information sent by the user equipment before sending the first information, wherein the second information is used to request early uplink synchronization.

[0214] In some embodiments, base station 6 is further configured to receive a measurement report sent by user equipment before sending the first information.

[0215] Figure 7 A schematic diagram of the structure of a communication system according to some embodiments of the present disclosure is shown. For example... Figure 7 As shown, the communication system 7 includes the user equipment 5 as described above, and the base station 6 as described above.

[0216] Figure 8 A schematic diagram of the structure of an electronic device according to some embodiments of the present disclosure is shown. For example... Figure 8 As shown, the electronic device 8 includes a processor 81 and a memory 82 coupled to the processor 81, the processor 81 being configured to execute communication methods in any of the embodiments of this disclosure based on instructions stored in the memory 82.

[0217] The memory 82 may include, for example, system memory, fixed non-volatile storage media, etc. The system memory stores, for example, the operating system, application programs, boot loader, database, and other programs.

[0218] Figure 9 A schematic diagram of the structure of an electronic device according to other embodiments of the present disclosure is shown. For example... Figure 9 As shown, the electronic device 9 in this embodiment includes a memory 91 and a processor 92, which are similar to those of memory 81 and processor 82. It may also include an input / output interface 93, a network interface 94, a storage interface 95, etc. These interfaces 93, 94, 95, and the memory 91 and processor 92 can be connected, for example, via a bus 96. The input / output interface 93 provides a connection interface for input / output devices such as a display, mouse, keyboard, and touchscreen. The network interface 94 provides a connection interface for various networked devices, such as connecting to a database server or cloud storage server. The storage interface 95 provides a connection interface for external storage devices such as SD cards and USB flash drives.

[0219] Embodiments of this disclosure also provide a computer-readable storage medium having a computer program stored thereon, characterized in that the program, when executed by a processor, implements any of the aforementioned communication methods.

[0220] Embodiments of this disclosure also provide a computer program product including instructions that, when executed by a processor, cause the processor to perform any of the foregoing communication methods.

[0221] Those skilled in the art will understand that embodiments of this disclosure can be provided as methods, systems, or computer program products. Therefore, this disclosure can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this disclosure can take the form of a computer program product embodied on one or more computer-usable non-transitory storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0222] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0223] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0224] The above description is only a preferred embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A communication method, executed by a user equipment, comprising: Receive first information sent by the base station, wherein the first information includes uplink timing adjustment information of one or more candidate cells; If the handover execution conditions of the first candidate cell are met and the first candidate cell has valid uplink timing adjustment information, the handover process of skipping random access RACH-LESS is executed.

2. The communication method according to claim 1 further includes: Before receiving the first information, a second information is sent to the base station, wherein the second information is used to request early uplink synchronization.

3. The communication method according to claim 2, wherein, The second information includes any one of the following: Instruction information is used to instruct the user equipment to request early uplink synchronization; Information on one or more candidate cells.

4. The communication method according to claim 3, wherein, The information of the candidate cells includes at least one of the following: The identifier of the candidate cell; One or more beam information associated with the candidate cell; The layer 3 measurement results of the candidate cells; Layer-1 measurement results of the beam associated with the candidate cell.

5. The communication method according to claim 2, wherein, Sending the second information to the base station includes: In response to the specified condition being met, the second information is sent to the base station.

6. The communication method according to claim 5, wherein, The specified conditions include at least one of the following: The first condition determined according to the switching execution conditions; The second condition used to trigger early uplink synchronization.

7. The communication method according to claim 6, wherein, The switching execution conditions include at least one of the following: the execution conditions of the conditional switching CHO and the execution conditions of the conditional LTM based on the mobility LTM configuration triggered by layer 1 or layer 2.

8. The communication method according to claim 6, wherein, The second condition includes the serving cell quality being lower than the first threshold and the candidate cell quality being higher than the second threshold.

9. The communication method according to claim 6, wherein, The second condition includes the serving cell having a beam quality lower than a third threshold and the candidate cell having a beam quality higher than a fourth threshold.

10. The communication method according to claim 6, wherein, The specified conditions also include at least one of the following: The user equipment is configured to request early uplink synchronization using the second information; The number of times the user equipment requests early uplink synchronization using the second information is less than the fifth threshold; The user equipment does not have any valid uplink timing adjustment information for any candidate cell or candidate cell group; The first timer is not running.

11. The communication method according to claim 2 or 10, further comprising: In response to sending the second information to the base station, a first timer is started; In response to receiving the first information, the first timer is stopped.

12. The communication method according to claim 2, wherein, The second information is sent via Layer 1 signaling, Layer 2 signaling, or Radio Resource Control (RRC) signaling.

13. The communication method according to claim 1, further comprising: Before receiving the first information, a measurement report is sent to the base station.

14. The communication method according to claim 1, wherein, The one or more candidate cells belong to one or more candidate cell groups, and the uplink timing adjustment information of the candidate cells in each candidate cell group is the same.

15. The communication method according to claim 1 or 14, wherein, The first candidate cell is a cell among the one or more candidate cells, or a cell that belongs to the same candidate cell group as a cell among the one or more candidate cells.

16. The communication method according to claim 1, further comprising: In response to receiving uplink timing adjustment information from the one or more candidate cells, for each of the one or more candidate cells, a second timer corresponding to the candidate cell is started or restarted; Based on the second timer corresponding to the one or more candidate cells, determine whether the first candidate cell has valid uplink timing adjustment information.

17. The communication method according to claim 16, wherein, Determining whether the first candidate cell has valid uplink timing adjustment information includes: When the second timer corresponding to the first candidate cell is running, and it is determined that the first candidate cell has valid uplink timing adjustment information; or If the second timer corresponding to the first candidate cell is not running, or the running time exceeds the first specified time, it is determined that the first candidate cell does not have valid uplink timing adjustment information.

18. The communication method according to claim 1, wherein, The one or more candidate cells belong to one or more candidate cell groups, and the uplink timing adjustment information of the candidate cells is the same as the uplink timing adjustment information of the candidate cell group to which the candidate cells belong. The communication method further includes: In response to receiving uplink timing adjustment information for one or more candidate cell groups, for each candidate cell group in the one or more candidate cell groups, a third timer corresponding to the candidate cell group is started or restarted; Based on the third timer corresponding to the one or more candidate cell groups, it is determined whether the first candidate cell has valid uplink timing adjustment information.

19. The communication method according to claim 18, wherein, Determining whether the first candidate cell has valid uplink timing adjustment information includes: If the third timer corresponding to the first candidate cell is running, it is determined that the first candidate cell has valid uplink timing adjustment information; or If the third timer corresponding to the first candidate cell is not running, or the running time exceeds the second specified time, it is determined that the first candidate cell does not have valid uplink timing adjustment information.

20. The communication method according to any one of claims 1 to 10, further comprising: If the first candidate cell does not have valid uplink timing adjustment information and the specified conditions are met, the second information is sent to the base station.

21. The communication method according to any one of claims 1 to 10, further comprising: Before receiving the first information, the third information sent by the base station is received; Based on the aforementioned third information, advance uplink synchronization is performed.

22. The communication method according to claim 21, wherein, The third information includes the identifiers of one or more candidate cells and at least one of the Physical Random Access Channel (PRACH) resources.

23. The communication method according to claim 1, further comprising: After the handover process is triggered, the uplink timing adjustment information of the first candidate cell is applied to the primary timing advance group PTAG, and the fourth timer corresponding to the PTAG is started or restarted.

24. The communication method according to claim 23, further comprising: Stop the second timer corresponding to the first candidate cell.

25. The communication method according to claim 23, further comprising: The remaining runtime of the second timer corresponding to the first candidate cell is used as the runtime of the fourth timer; or The remaining runtime of the third timer corresponding to the candidate cell group to which the first candidate cell belongs is used as the runtime of the fourth timer.

26. The communication method according to claim 1, further comprising: After the handover process is triggered, the uplink timing adjustment information of the first candidate cell is applied to the PTAG; Alternatively, the second timer corresponding to the first candidate cell can be used as the fourth timer corresponding to the PTAG, or the third timer corresponding to the candidate cell group to which the first candidate cell belongs can be used as the fourth timer corresponding to the PTAG.

27. The communication method according to claim 1, further comprising: After the handover process is triggered, the uplink timing adjustment information of the first candidate cell is applied to the PTAG; Continue running the second timer corresponding to the first candidate cell, or continue running the third timer corresponding to the candidate cell group to which the first candidate cell belongs.

28. The communication method according to claim 27, further comprising: Uplink transmission of the serving cell within the PTAG is performed during the operation of the second timer or the third timer.

29. The communication method according to claim 1, further comprising: After the handover process is triggered, the second timer corresponding to other candidate cells besides the first candidate cell is stopped, or the third timer corresponding to other candidate cell groups besides the candidate cell group to which the first candidate cell belongs is stopped.

30. The communication method according to claim 1 or 29, further comprising: After the handover process is triggered, the uplink timing adjustment information of other candidate cells or other candidate cell groups, except for the uplink timing adjustment information of the first candidate cell, is deleted.

31. The communication method according to claim 1, further comprising: After the handover process is triggered, the second timer corresponding to other candidate cells besides the first candidate cell continues to run, or the third timer corresponding to other candidate cell groups besides the candidate cell group to which the first candidate cell belongs continues to run.

32. The communication method according to claim 1 or 31, further comprising: Based on the indication information of the base station, it is determined whether to delete or retain uplink timing adjustment information of other candidate cells or other candidate cell groups, other than the uplink timing adjustment information of the first candidate cell, after switching to the first candidate cell.

33. A user equipment, comprising: The receiving module is configured to receive first information sent by the base station, wherein the first information includes uplink timing adjustment information of one or more candidate cells; The execution module is configured to perform a handover process that skips random access RACH-LESS when the handover execution conditions of the first candidate cell are met and the first candidate cell has valid uplink timing adjustment information.

34. A communication system, comprising: The user equipment as described in claim 33; and The base station is configured to send first information to the user equipment, wherein the first information includes uplink timing adjustment information for one or more candidate cells.

35. The communication system according to claim 34, wherein, The base station is further configured as follows: Before sending the first information, the system receives a second information sent by the user equipment, wherein the second information is used to request early uplink synchronization.

36. The communication method according to claim 34, wherein, The base station is further configured as follows: Before sending the first information, a measurement report sent by the user equipment is received.

37. An electronic device comprising: processor; as well as A memory coupled to the processor is used to store instructions that, when executed by the processor, cause the processor to perform the communication method as described in any one of claims 1 to 32.

38. A computer-readable storage medium having a computer program stored thereon, wherein, When the program is executed by the processor, it implements the communication method as described in any one of claims 1 to 32.

39. A computer program product comprising instructions that, when executed by a processor, cause the processor to perform the communication method as described in any one of claims 1 to 32.

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