Terminal handover method, terminal, network side device, network device and system

Abstract

The present disclosure provides a terminal switching method, a terminal, a network side device, a network device and a system, and relates to the technical field of wireless communication. The terminal switching method provided by the present disclosure comprises the following steps: a terminal located in a non-ground network receives a random access channel-free switching instruction, wherein the random access channel-free switching instruction comprises timing advance compensation auxiliary information; the terminal determines a timing advance compensation value according to the timing advance compensation auxiliary information; and the terminal sends initial access information to the non-ground network based on the timing advance compensation value.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of wireless communication, and in particular to a terminal switching method, a terminal, a network side device, a network device and a system. BACKGROUND

[0002] With the 3GPP R17 version frozen, Non-Terrestrial Network (NTN) introduces satellite nodes into mobile communication networks, and terminals can access networks through satellites, greatly improving network coverage.

[0003] The communication delay of the satellite node is much larger than that of the terrestrial cellular network, and too large delay can easily lead to switching failure. SUMMARY

[0004] One purpose of the present disclosure is to propose a terminal switching scheme in NTN to improve the success rate of switching.

[0005] According to an aspect of some embodiments of the present disclosure, a terminal switching method is proposed, comprising: a terminal located in a NTN (non-terrestrial network) receiving a RACH-less (Random Access Channel-less) switching instruction, the RACH-less switching instruction including TA (Time Advance) compensation auxiliary information; the terminal determining a TA compensation value according to the TA compensation auxiliary information; and the terminal sending initial access information to the NTN based on the TA compensation value.

[0006] In some embodiments, the TA compensation auxiliary information includes ephemeris information.

[0007] In some embodiments, the TA compensation auxiliary information further includes feeder link TA compensation information.

[0008] In some embodiments, the RACH-less switching instruction further includes pre-allocated time-frequency resource configuration information, and the terminal switching method further comprises: the terminal storing the time-frequency resource configuration information.

[0009] In some embodiments, the method further comprises: the terminal obtaining the pre-allocated time-frequency resource configuration information through RRC (Radio Resource Control) information and storing it.

[0010] In some embodiments, the terminal sending initial access information to the NTN based on the TA compensation value comprises: after the terminal determines the TA compensation value, the terminal sends initial access information to the NTN based on the TA compensation value according to the stored time-frequency resource configuration information.

[0011] In some embodiments, the method further comprises: receiving, by the terminal, dynamic grant information of the target cell through DCI (Downlink Control Information); and sending, by the terminal, the initial access information to the NTN based on the TA compensation value, including: sending, by the terminal, the initial access information to the NTN based on the TA compensation value according to the dynamic grant information after receiving the dynamic grant information.

[0012] In some embodiments, determining, by the terminal, the TA compensation value according to the TA compensation assistance information includes: determining a feeder link TA compensation value according to the feeder link TA compensation information; determining a specific user equipment TA compensation value according to the ephemeris information; and determining the TA compensation value according to the feeder link TA compensation value and the specific user equipment TA compensation value.

[0013] In some embodiments, determining, by the terminal, the TA compensation value according to the TA compensation assistance information further includes: determining a TA compensation measurement value by the terminal; and determining the TA compensation value according to the feeder link TA compensation value and the specific user equipment TA compensation value, including: determining the TA compensation value according to the feeder link TA compensation value and the specific user equipment TA compensation value, in combination with the TA compensation measurement value, a TA offset, and a unit time length.

[0014] In some embodiments, determining the TA compensation measurement value includes: in a case where the satellites corresponding to the source cell and the target cell are the same, the TA compensation measurement value is the same as the source cell.

[0015] In some embodiments, determining the TA compensation measurement value includes: in a case where the satellites corresponding to the source cell and the target cell are not the same, the TA compensation measurement value is a predetermined value.

[0016] In some embodiments, the method further comprises: receiving, by the terminal, access confirmation information, and determining, by the terminal, that the access is successful according to the access confirmation information.

[0017] In some embodiments, the access confirmation information is carried through a MAC (Medium Access Control) CE (Control Element).

[0018] In some embodiments, the method further comprises: obtaining, by the terminal, downlink data through a PDCCH (Physical Downlink Control Channel) or a PDSCH (Physical Uplink Shared Channel) scrambled by a C-RNTI (Cell-Radio Network Temporary Identifier), wherein the terminal determines that the access is successful according to the downlink data.

[0019] According to an aspect of some embodiments of the present disclosure, a terminal handover method is provided, comprising: a network side device of an NTN sending handover preparation information to a target cell of a terminal handover; the network side device sending a RACH-less handover instruction, wherein the RACH-less handover instruction includes TA compensation auxiliary information.

[0020] In some embodiments, the RACH-less handover instruction further includes pre-allocated time-frequency resource configuration information for the terminal.

[0021] In some embodiments, the method further comprises: sending the pre-allocated time-frequency resource configuration information to the terminal through RRC information.

[0022] In some embodiments, the method further comprises: receiving dynamic authorization information from the target cell; and sending the dynamic authorization information to the terminal through DCI.

[0023] According to an aspect of some embodiments of the present disclosure, a terminal handover method is provided, comprising: a network side device of an NTN obtaining handover preparation information from a source cell of a terminal handover; the network side device obtaining initial access information of the terminal; and sending downlink data through a PDCCH or a PDSCH scrambled by a C-RNTI.

[0024] In some embodiments, the method further comprises: sending access confirmation information to the terminal.

[0025] In some embodiments, the access confirmation information is carried through a MAC CE.

[0026] In some embodiments, the method further comprises: after receiving the handover preparation information, the network side device generates dynamic authorization information of the terminal; and sending the dynamic authorization information to the source cell.

[0027] According to an aspect of some embodiments of the present disclosure, a terminal is provided, comprising: an information obtaining unit configured to receive a RACH-less handover instruction from a source cell of an NTN, wherein the RACH-less handover instruction includes TA compensation auxiliary information; a compensation value determining unit configured to determine a TA compensation value according to the TA compensation auxiliary information; and an access unit configured to send initial access information to a target cell of the NTN based on the TA compensation value.

[0028] In some embodiments, the TA compensation auxiliary information includes ephemeris information and feeder link TA compensation information.

[0029] In some embodiments, the RACH-less handover instruction further includes pre-allocated time-frequency resource configuration information, and the information obtaining unit is further configured to store the time-frequency resource configuration information.

[0030] In some embodiments, the information obtaining unit is further configured to obtain the pre-allocated time-frequency resource configuration information through RRC information and store.

[0031] In some embodiments, the access unit is configured to, after the TA compensation value determination unit determines the TA compensation value, send the initial access information to the NTN based on the TA compensation value according to the stored time-frequency resource configuration information.

[0032] In some embodiments, the information obtaining unit is further configured to receive dynamic grant information of the target cell through DCI; and the access unit is configured to, after receiving the dynamic grant information, send the initial access information to the NTN based on the TA compensation value according to the dynamic grant information.

[0033] In some embodiments, the information obtaining unit is further configured to perform at least one of the following: receive access confirmation information, wherein the terminal determines access success according to the access confirmation information; or obtain downlink data through PDCCH or PDSCH scrambled by C-RNTI, wherein the terminal determines access success according to the downlink data.

[0034] According to an aspect of some embodiments of the present disclosure, a network side device of an NTN is provided, comprising: a handover preparation interaction unit configured to send handover preparation information to a target cell of a terminal; and an information sending unit configured to send a RACH-less handover instruction, wherein the TA compensation auxiliary information is included in the RACH-less handover instruction.

[0035] In some embodiments, the RACH-less handover instruction further includes time-frequency resource configuration information pre-allocated for the terminal.

[0036] In some embodiments, the information sending unit is further configured to send the pre-allocated time-frequency resource configuration information to the terminal through radio resource control information.

[0037] In some embodiments, the handover preparation interaction unit is further configured to receive dynamic grant information from the target cell; and the information sending unit is further configured to send the dynamic grant information to the terminal through downlink control information.

[0038] According to an aspect of some embodiments of the present disclosure, a network side device of an NTN is provided, comprising: a handover preparation unit configured to obtain handover preparation information from a source cell of a terminal; an access information receiving unit configured to obtain initial access information of the terminal; and an access confirmation unit configured to send downlink data through a physical downlink control channel or a physical downlink shared channel scrambled by a cell radio network temporary identifier.

[0039] In some embodiments, the access confirmation unit is further configured to send access confirmation information to the terminal.

[0040] In some embodiments, the handover preparation unit is further configured to generate dynamic grant information of the terminal after receiving the handover preparation information, and send the dynamic grant information to the source cell.

[0041] According to an aspect of some embodiments of the present disclosure, a network device is provided, comprising: a memory; and a processor coupled to the memory, the processor configured to execute any of the methods mentioned above based on instructions stored in the memory.

[0042] According to an aspect of some embodiments of the present disclosure, a computer readable storage medium is provided, having stored thereon computer program instructions which, when executed by a processor, implement the steps of any of the methods mentioned above.

[0043] According to an aspect of some embodiments of the present disclosure, a network side system of an NTN is provided, comprising: a first network side device configured to perform any of the terminal handover methods mentioned above on the source cell side of the terminal handover; and a second network side device configured to perform any of the terminal handover methods mentioned above on the target cell side of the terminal handover.

[0044] According to an aspect of some embodiments of the present disclosure, an NTN system is provided, comprising: a terminal configured to perform any of the methods performed by the terminal mentioned above; and network side devices, wherein at least one network side device is configured to perform any of the terminal handover methods mentioned above on the source cell side of the terminal handover; and at least one network side device is configured to perform any of the terminal handover methods mentioned above on the target cell side of the terminal handover. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings, which are included to provide a further understanding of the present disclosure and constitute a part of the present disclosure, illustrate embodiments of the present disclosure and together with the description serve to explain the present disclosure, and do not limit the present disclosure in any way. In the drawings:

[0046] Figure 1 Flowchart for some embodiments of the terminal handover method of the present disclosure.

[0047] Figure 2 Flowchart for some other embodiments of the terminal handover method of the present disclosure.

[0048] Figure 3 Flowchart for some other embodiments of the terminal handover method of the present disclosure.

[0049] Figure 4 Signaling flowchart for some embodiments of the terminal handover method of the present disclosure.

[0050] Figure 5Signaling flowcharts for some other embodiments of the terminal handover method disclosed herein.

[0051] Figure 6 These are schematic diagrams illustrating some embodiments of the terminals disclosed herein.

[0052] Figure 7 These are schematic diagrams illustrating some embodiments of the network-side devices of the NTN disclosed herein.

[0053] Figure 8 These are schematic diagrams of other embodiments of the network-side devices of the NTN disclosed herein.

[0054] Figure 9 These are schematic diagrams illustrating some embodiments of the network devices disclosed herein.

[0055] Figure 10 These are schematic diagrams illustrating other embodiments of the network devices disclosed herein.

[0056] Figure 11 This is a schematic diagram of some embodiments of the network-side system of the NTN disclosed herein.

[0057] Figure 12 This is a schematic diagram of some embodiments of the NTN system disclosed herein. Detailed Implementation

[0058] The technical solutions of this disclosure will be further described in detail below with reference to the accompanying drawings and embodiments.

[0059] RACH-less, as a method that skips the random access process and directly hands over to the target cell, can significantly reduce access latency. However, current standards only support RACH-less schemes for terrestrial cellular networks, and the TA compensation value is either 0 or the same as the source cell base station value. The TA compensation process in non-terrestrial networks is relatively complex, requiring consideration of factors such as the feeder link, ephemeris information, and terminal location information. Furthermore, due to the higher communication latency, the communication process should be simplified as much as possible to reduce frequent interactions between the terminal and the network.

[0060] Flowcharts of some embodiments of the terminal switching method disclosed herein are as follows: Figure 1 As shown. Figure 1 The terminal handover method is executed by the terminal, which is a terminal that receives wireless access services from NTN, or a terminal that supports obtaining network services through NTN.

[0061] In step 111, the terminal located in the NTN receives a random access channel switching (RACH-less HO) instruction, and the TA compensation assistance information is included in the RACH-less HO instruction. In some embodiments, the TA compensation assistance information is the information required by the terminal to calculate the TA compensation value. In some embodiments, the ephemeris information and the feeder link TA compensation information are included in the TA compensation assistance information, so as to facilitate the terminal to obtain the parameters for implementing the TA compensation of the NTN and improve the access efficiency. In some embodiments, the ephemeris information in the assistance information is the ephemeris information of the target cell.

[0062] In some embodiments, the RACH-less switching instruction can be issued by the network side device of the source cell (hereinafter referred to as the source cell, such as a satellite providing service for the source cell). In some embodiments, after determining that the terminal needs to perform RACH-less switching, the source cell performs switching preparation with the network side device of the target cell (hereinafter referred to as the target cell, such as a satellite providing service for the target cell).

[0063] In step 113, the terminal determines the TA compensation value according to the TA compensation assistance information. In some embodiments, the terminal determines the corresponding compensation parameters according to the ephemeris information and the feeder link TA compensation information, and then determines the TA compensation value in combination with the parameters for calculating the TA compensation value of the terminal in the related art, so as to improve the compatibility while adapting to the NTN scenario.

[0064] In some embodiments, the terminal determines the feeder circuit TA compensation value N TA,common according to the feeder link TA compensation information and the terminal self-positioning, and determines the specific user equipment TA compensation value N TA,UE-specific according to the ephemeris information. Further, the terminal determines the TA compensation value according to the feeder circuit TA compensation value and the specific user equipment TA compensation value.

[0065] In some embodiments, the terminal can also determine the TA compensation measurement value N TA . In the related art, the TA compensation measurement value N TA is carried by the TAC (Timing Advance Command) sent by the base station side to the UE through the MAC CE. The terminal acquires N TA with the source cell in the process of communicating with the source cell, and then determines whether the satellites corresponding to the target cell and the source cell are the same in the current step 113. If the target cell and the source cell are cells served by the same satellite, it is determined that the terminal has the same N TA with the target cell and the same N TA with the source cell, and the terminal uses the N TAThe current TA compensation value is calculated. In some embodiments, if the target cell and the source cell are cells served by different satellites, the N TA TA compensation value with the source cell is not suitable for being used with the target cell, and the N TA TA compensation value with the target cell can be set to a predetermined value, which is 0 in some embodiments. In this way, whether the satellites corresponding to the cells are the same or not can be considered to determine the corresponding N TA TA compensation value, thereby improving the accuracy probability of the N TA TA compensation value.

[0066] In some embodiments, the terminal determines the TA compensation value T TA,common based on the feeder link TA compensation value N TA,UE-specific and the specific user equipment TA compensation value N TA , in combination with the TA compensation measurement value N TA,offset , the TA offset value N c , and the unit time length T TA . In some embodiments, the TA compensation value T TA may be determined based on the formula below.

[0067] T TA = (N TA +N TA,UE-specific +N TA,commin +N TA,offset ) x T c (1)

[0068] In the formula above, N TA,offset is a fixed offset according to different frequency bands and subcarriers, and T c is the unit time length of the system.

[0069] In step 115, the terminal sends initial access information to the NTN based on the TA compensation value.

[0070] Based on the method in the above-mentioned embodiments, when sending the RACH-less handover instruction to the terminal, the network side device of the NTN source cell can provide auxiliary information for the terminal to calculate the TA compensation value suitable for the NTN. The terminal can timely and autonomously calculate the TA compensation value based on the current technology in combination with the auxiliary information, and perform RACH-less handover, thereby simplifying the communication process of NTN terminal handover, overcoming the time delay caused by the satellite service link and the feeder link, reducing the probability of handover failure, and improving the handover efficiency.

[0071] In some embodiments, in step 115, the terminal sends the initial access information to the NTN based on the TA compensation value, and the wireless resource called by the initial access information can be pre-configured. In some embodiments, in step 111, the source cell can send the time-frequency resource configuration information to the terminal with the RACH-less handover instruction, and the terminal parses and stores the time-frequency resource configuration information for use in step 115. In some embodiments, the source cell can also send the pre-allocated time-frequency resource configuration information to the terminal in advance through RRC information, and the terminal parses and stores the time-frequency resource configuration information for use in step 115. In some embodiments, the pre-configured time-frequency resource configuration information can have a valid time, which is determined by the source cell according to ephemeris information and requirements. The terminal needs to perform step 115 within the valid time.

[0072] Through such a method, resources can be pre-configured in advance before handover occurs, avoiding the probability of conflict between multiple users, and solving the problem that frequent handover of terminals in NTN cells can easily cause conflicts.

[0073] In some embodiments, in step 115, the terminal sends the initial access information to the NTN based on the TA compensation value, and the wireless resource called by the initial access information can be real-time configured. In some embodiments, the terminal receives dynamic authorization information of the target cell through DCI. In some embodiments, the DCI can be sent by the source cell to the terminal, and the source cell sends the dynamic authorization information of the terminal to the terminal through the DCI after obtaining the dynamic authorization information from the target cell. After receiving the dynamic authorization information, the terminal immediately sends the initial access information to the NTN based on the TA compensation value calculated in step 113 according to the dynamic authorization information.

[0074] Through such a method, the terminal can be triggered by DCI to immediately initiate the RACH-less process, which is more suitable for scenarios with high environmental changes.

[0075] In some embodiments, the terminal handover method further includes step 117, in which the terminal receives access confirmation information, and determines access success according to the access confirmation information. In some embodiments, the access confirmation information can be information issued by the target cell through a link layer control element MAC CE after confirming the access of the terminal, and the terminal determines access success according to the information. In some embodiments, the operation of issuing the access confirmation information through the MAC CE can be skipped, and the target cell sends downlink data through a physical downlink control channel or a physical downlink shared channel PDCCH / PDSCH scrambled by a cell radio network temporary identifier C-RNTI, and the terminal determines access success when receiving the downlink data through the PDCCH / PDSCH scrambled by the C-RNTI.

[0076] Through the method, if the network has terminal downlink data to send after the RACH-less handover succeeds, the access success MAC CE message can be not sent, and the C-RNTI scrambling PDCCH / PDSCH is directly sent, so that the signaling interaction is reduced and the data transmission real-time performance is improved.

[0077] A flowchart of another embodiment of the terminal handover method of the present disclosure is shown in FIG. 6. Figure 2 Figure 2 The method in the embodiment shown is performed by a network side device of an NTN, such as a satellite. In some embodiments, the network side device of the NTN can serve as a network side device on the source cell side of terminal handover, or as a network side device on the target cell side of terminal handover. In some embodiments, when the network side device of the NTN serves as the network side device on the source cell side, the method in the embodiment shown in FIG. 5 can be performed. Figure 2

[0078] In step 221, the network side device of the NTN sends handover preparation information to the target cell of terminal handover. In some embodiments, the network side device of the NTN serving as the serving cell of the terminal can determine that the terminal needs to be handed over to another cell according to information such as terminal signal strength, quality, position, etc., and then determine the target cell for the terminal as the source cell and interact with the network side device of the target cell. In some embodiments, the information of the interaction with the network side device of the target cell can include relevant information of the terminal.

[0079] In step 223, the network side device of the NTN sends a RACH-less handover instruction to the terminal, and the TA compensation auxiliary information is included in the random access channel-free handover instruction. In some embodiments, the ephemeris information and the feeder link TA compensation information are included in the TA compensation auxiliary information, so that the terminal can obtain the parameters for implementing the TA compensation of the NTN, and the access efficiency is improved.

[0080] In some embodiments, the pre-allocated time-frequency resource configuration information for the terminal is also included in the random access channel-free handover instruction. Through this method, the resources can be pre-allocated before the handover occurs, and the probability of conflict between multiple users is avoided, solving the problem that the terminal handover in the NTN cell occurs frequently and easily causes conflict.

[0081] Through the method in the embodiment shown above, the network side device of the NTN source cell can provide auxiliary information for the terminal to calculate the TA compensation value suitable for the NTN when sending the RACH-less handover instruction to the terminal, so that the terminal can calculate the TA compensation value in time and independently based on the auxiliary information, and perform RACH-less handover, thereby simplifying the communication process of the NTN terminal handover, overcoming the time delay caused by the satellite service link and the feeder link, reducing the probability of handover failure, and improving the handover efficiency.​​

[0082] In some embodiments, the network-side equipment of the source cell can also send pre-allocated time-frequency resource configuration information to the terminal via RRC. The terminal parses the time-frequency resource configuration information and stores it for use when sending initial access information to the target cell. This achieves resource pre-allocation, avoids the probability of conflicts between multiple users, and solves the problem of frequent terminal handovers in NTN cells that easily cause conflicts.

[0083] In some embodiments, the network-side device of the source cell can receive dynamic authorization information provided by the target cell and send the dynamic authorization information to the terminal via DCI. After receiving the dynamic authorization information, the terminal immediately sends initial access information to the NTN based on the calculated TA compensation value according to the dynamic authorization information.

[0084] This method enables the DCI-triggered terminal to immediately initiate a RACH-less process, making it more suitable for scenarios with highly variable environments.

[0085] Flowcharts of some further embodiments of the terminal switching method disclosed herein are as follows: Figure 3 As shown. Figure 3 The method in the illustrated embodiment is executed by an NTN network-side device, such as a satellite. In some embodiments, the NTN network-side device can act as either the source cell network-side device or the target cell network-side device for terminal handover. In some embodiments, when the NTN network-side device acts as the target cell network-side device, it can execute the following... Figure 2 The method in the illustrated embodiment.

[0086] In step 331, the NTN network-side device obtains handover preparation information from the source cell to which the terminal is handing over. In some embodiments, after determining that the terminal needs to hand over and selecting a target cell, the source cell network-side device sends handover preparation information to the target cell network-side device. The target cell network-side device receives this handover preparation information. In some embodiments, the target cell network-side device may determine whether to allow the terminal to hand over and provide feedback information. In some embodiments, if the terminal is allowed to hand over to this cell, feedback is sent to the source cell network-side device so that the source cell network-side device can perform step 223 described above.

[0087] In step 333, the network-side device obtains the initial access information of the terminal. In some embodiments, the terminal may perform the following... Figure 1 The method in the corresponding embodiment sends initial access information.

[0088] In some embodiments, the radio resources upon which the initial access information is based can be pre-configured to the terminal in accordance with any of the embodiments described above. In some embodiments, after the network-side device of the target cell determines in step 331 that the terminal is allowed to switch to the local cell, it can generate dynamic authorization information for the terminal and send the dynamic authorization information to the source cell, which then provides it to the terminal. The terminal then sends the initial access information based on the dynamic authorization information.

[0089] In step 335, the network-side device of the NTN target cell can send access confirmation information to the terminal via MAC CE after step 333 above, so that the terminal can be notified of the successful handover in a timely manner.

[0090] In some embodiments, when there is a need for downlink data transmission, the network-side equipment of the NTN target cell can skip the step of sending access confirmation information to the terminal and directly send downlink data to the terminal through the C-RNTI scrambled PDCCH / PDSCH.

[0091] With this method, after a successful RACH-less handover, if there are terminals sending downlink data in the network, the MAC CE message indicating successful access can be skipped, and a C-RNTI scrambled PDCCH / PDSCH can be sent directly, reducing signaling interaction while improving the real-time performance of data transmission.

[0092] Signaling flowcharts of some embodiments of the terminal handover method disclosed herein are as follows: Figure 4 As shown.

[0093] In steps 401-402, the source cell 42 of the NTN network performs a handover decision for terminal 41. If it is determined that a cell handover is required for terminal 41, a target cell 43 is determined, and handover preparation is performed with the target cell 43. If the target cell 43 determines that it can accept terminal 41, step 403 is executed.

[0094] In step 403, the source cell 42 issues a RACH-less handover command instructing the terminal to perform a RACH-less handover. This command includes TA compensation auxiliary information, such as the ephemeris information of the target satellite and the TA compensation information of the feeder link. In some embodiments, the RACH-less handover command may also include pre-configured time and frequency resource configuration information for the terminal to hand over to the target cell.

[0095] In some embodiments, the source cell 42 may send time-frequency resource configuration information to the terminal at any time before step 405 below (including a time earlier than before sending the RACH-less handover instruction).

[0096] In some embodiments, the source cell needs to combine ephemeris data with network requirements to specify the effective time period for time-frequency resource configuration information. The terminal sends an initial access message within this effective time period.

[0097] In step 404, terminal 41 calculates the final TA compensation value T based on its own location information, target cell ephemeris information, and feeder link TA compensation value. TA In some embodiments, the calculation method may be as shown in formula (1) above.

[0098] In some embodiments, if the target cell corresponds to the same satellite as the source cell, N TA The value is the same as the original cell. If the target cell corresponds to a different satellite and the source cell, N TA The value is a predetermined value, such as 0. Terminal 41 can calculate N based on its location and ephemeris information. TA,UE-specific Based on the TA compensation value of the feeder link, N can be obtained. TA,common .

[0099] In step 405, terminal 41 sends an initial access message to target cell 43 based on the TA compensation value. In some embodiments, the RRCReconfigurationComplete message can be reused to send the initial access message.

[0100] In step 406, after receiving the RRCReconfigurationComplete message, the target cell 43 sends an access confirmation message to the terminal. In some embodiments, the confirmation message may be a MAC CE, indicating that the RACH-less handover of the terminal was successful; if the target cell 43 has downlink data that needs to be sent to the terminal 41, it can directly send a C-RNTI scrambled PDCCH / PDSCH, skipping the step of sending the MAC CE confirmation message.

[0101] Using the method described in the above embodiments, the source cell can send TA compensation auxiliary information to the terminal. Combined with this information and its own location information, the terminal can compensate for the TA value itself, overcoming the latency impact caused by the satellite service link and the feeder link. By providing the terminal with time and frequency resource configuration information in a pre-configured manner and indicating the effective time corresponding to the time and frequency resource configuration information, the probability of conflicts between multiple users can be avoided. After a successful RACH-less handover, if the network has a terminal sending downlink data, the MAC CE message indicating successful access can be skipped, and the PDCCH / PDSCH scrambled by C-RNTI can be sent directly, reducing signaling interaction while improving the real-time performance of data transmission.

[0102] Signaling flowcharts for other embodiments of the terminal handover method disclosed herein are as follows: Figure 5 As shown.

[0103] Steps 501 and 502 are similar to steps 401 and 402 above, respectively.

[0104] In step 503, the source cell 52 issues a RACH-less handover command to instruct the terminal to perform RACH-less handover. The command includes TA compensation auxiliary information, such as the ephemeris information of the target satellite and the TA compensation information of the feeder link.

[0105] In step 504, terminal 51 calculates the final TA compensation value T based on its own location information, target cell ephemeris information, and feeder link TA compensation value. TA In some embodiments, the calculation method may be as shown in formula (1) above.

[0106] In some embodiments, if the target cell corresponds to the same satellite as the source cell, N TA The value is the same as the original cell. If the target cell corresponds to a different satellite and the source cell, N TA The value is a predetermined value, such as 0. Terminal 51 can calculate N based on its location and ephemeris information. TA,UE-specific Based on the TA compensation value of the feeder link, N can be obtained. TA,common .

[0107] In step 505, the target cell 53 grants uplink authorization to the terminal 51 and sends dynamic authorization information to the terminal 51 via DCI through the source cell 52.

[0108] In step 506, after receiving the dynamic authorization information, terminal 51 immediately sends an initial access message to the network side based on the TA compensation value obtained in step 503. In some embodiments, the RRCReconfigurationComplete message can be reused to send the initial access message.

[0109] In step 507, after receiving the RRCReconfigurationComplete message, the target cell 53 sends an access confirmation message to the terminal. In some embodiments, the confirmation message may be a MAC CE, indicating that the RACH-less handover of the terminal was successful; if the target cell 53 has downlink data that needs to be sent to the terminal 51, it can directly send a C-RNTI scrambled PDCCH / PDSCH, skipping the step of sending the MAC CE confirmation message.

[0110] Using the method described in the above embodiments, the source cell can send TA compensation auxiliary information to the terminal. Combined with this information and its own location information, the terminal can compensate for the TA value itself, overcoming the latency impact caused by the satellite service link and the power supply link. The DCI provides dynamic authorization information to the terminal so that the terminal can send initial access information, which is suitable for scenarios with highly variable environments. After a successful RACH-less handover, if the network has downlink data to send, the MAC CE message indicating successful access can be skipped, and the PDCCH / PDSCH scrambled by C-RNTI can be sent directly, reducing signaling interaction while improving the real-time performance of data transmission.

[0111] Schematic diagrams of some embodiments of the terminal disclosed herein are shown below. Figure 6 As shown. In some embodiments, the terminal is a terminal for which wireless access services are provided by NTN, or a terminal that supports the ability to obtain network services through NTN.

[0112] The information acquisition unit 611 can receive a RACH-less handover command from the source cell of the NTN, which includes TA compensation auxiliary information. In some embodiments, the TA compensation auxiliary information is information required by the terminal to calculate the TA compensation value. In some embodiments, the TA compensation auxiliary information includes ephemeris information and feeder link TA compensation information, thereby facilitating the terminal to obtain parameters for implementing TA compensation of the NTN and improving access efficiency. In some embodiments, the ephemeris information in the auxiliary information is the ephemeris information of the target cell.

[0113] The compensation value determination unit 612 can determine the TA compensation value based on the TA compensation auxiliary information. In some embodiments, the terminal determines the corresponding compensation parameters based on the ephemeris information and the power supply link TA compensation information, and then combines the parameters used by the terminal to calculate the TA compensation value in related technologies to determine the TA compensation value, thereby improving compatibility while adapting to NTN scenarios. In some embodiments, the compensation value determination unit 612 can determine the TA compensation value based on the method in any embodiment of step 113 above.

[0114] Access unit 613 can send initial access information to the target cell of NTN based on TA compensation value.

[0115] Such terminals can use RACH-less handover commands to obtain auxiliary information for calculating TA compensation values ​​applicable to NTN, and combine the auxiliary information to autonomously calculate TA compensation values ​​in a timely manner to perform RACH-less handover. This simplifies the communication process for NTN terminal handover, overcomes the time delay impact caused by satellite service links and feeder links, reduces the probability of handover failure, and improves handover efficiency.

[0116] In some embodiments, the information acquisition unit 611 can also acquire and store pre-allocated time-frequency resource configuration information. In some embodiments, the time-frequency resource configuration information can be acquired with a RACH-less handover instruction or through RRC information. In some embodiments, after the compensation value determination unit 612 determines the TA compensation value, the access unit 613 can send initial access information to the NTN based on the stored time-frequency resource configuration information and the TA compensation value.

[0117] Such terminals can pre-allocate resources before handover occurs, avoiding the probability of conflicts between multiple users and solving the problem of frequent terminal handovers causing conflicts in NTN cells.

[0118] In some embodiments, the information acquisition unit 611 can receive dynamic grant information from the target cell via downlink control information. Upon receiving the dynamic grant information, the access unit 613 can send initial access information to the NTN based on the TA compensation value. Such a terminal can immediately initiate a RACH-less process via DCI trigger, making it more suitable for scenarios with highly variable environments.

[0119] In some embodiments, the information acquisition unit 611 can also receive access confirmation information, wherein the terminal determines successful access based on the access confirmation information. In some embodiments, the information acquisition unit 611 can also acquire downlink data through C-RNTI scrambled PDCCH or PDSCH, and the terminal does not need to receive separate access success information, but determines successful access based on the received downlink data. Such a terminal can improve the real-time performance of data transmission while reducing signaling interaction.

[0120] Schematic diagrams of some embodiments of the network-side devices of the NTN disclosed herein are shown below. Figure 7 As shown.

[0121] The handover preparation interaction unit 721 can send handover preparation information to the target cell for the terminal's handover. In some embodiments, the network-side device of the serving cell NTN, which is the terminal, can determine whether the terminal needs to be handed over to another cell based on information such as the terminal's signal strength, quality, and location. The handover preparation interaction unit 721 then interacts with the network-side device of the target cell. In some embodiments, the information exchanged may include relevant information about the terminal.

[0122] The information sending unit 722 can send a RACH-less handover command to the terminal. The RACH-less handover command includes TA compensation auxiliary information. In some embodiments, the TA compensation auxiliary information includes ephemeris information and feeder link TA compensation information, thereby facilitating the terminal to obtain the parameters for implementing TA compensation in NTN and improving access efficiency.

[0123] In some embodiments, the no-random-access-channel handover instruction also includes time-frequency resource configuration information pre-allocated to the terminal, thereby enabling resources to be pre-allocated before the handover occurs, avoiding the probability of conflicts between multiple users, and solving the problem that frequent terminal handovers in NTN cells can easily cause conflicts.

[0124] When such network-side equipment sends RACH-less handover commands to terminals, it can provide auxiliary information to enable terminals to calculate TA compensation values ​​applicable to NTN. This allows terminals to combine the auxiliary information to calculate TA compensation values ​​autonomously in a timely manner and perform RACH-less handover, thereby simplifying the communication process for NTN terminal handover, overcoming the latency effects caused by satellite service links and feeder links, reducing the probability of handover failure, and improving handover efficiency.

[0125] In some embodiments, the information sending unit 722 can also send pre-allocated time-frequency resource configuration information to the terminal through radio resource control information. The terminal parses the time-frequency resource configuration information and stores it for use when the terminal sends initial access information to the target cell. This achieves resource pre-allocation, avoids the probability of conflicts between multiple users, and solves the problem that frequent terminal handovers in NTN cells can easily cause conflicts.

[0126] In some embodiments, the handover preparation interaction unit 721 can also receive dynamic grant information from the target cell. The information sending unit 722 can also send the dynamic grant information to the terminal via downlink control information. After receiving the dynamic grant information, the terminal immediately sends initial access information to the NTN based on the calculated TA compensation value according to the dynamic grant information.

[0127] Such network-side devices can trigger the terminal to immediately initiate a RACH-less process via DCI, making them more suitable for scenarios with highly variable environments.

[0128] Schematic diagrams of other embodiments of the network-side device of the NTN disclosed herein are as follows: Figure 8 As shown.

[0129] The handover preparation unit 831 can obtain handover preparation information from the source cell to which the terminal is handing over. In some embodiments, after determining that the terminal needs to hand over and selecting a target cell, the network-side device of the source cell sends handover preparation information to the network-side device of the target cell. The handover preparation unit 831 receives this handover preparation information. In some embodiments, the handover preparation unit 831 can determine whether to allow the terminal to hand over and provide feedback information. In some embodiments, if the terminal is allowed to hand over to the current cell, the handover preparation unit 831 provides feedback to the network-side device of the source cell so that the network-side device of the source cell can perform the above step 223.

[0130] In some embodiments, after the handover preparation unit 831 determines that the terminal is allowed to handover to the local cell, it can generate dynamic authorization information for the terminal and send the dynamic authorization information to the source cell, which then provides it to the terminal. The terminal then sends initial access information based on the dynamic authorization information.

[0131] The access information receiving unit 832 is capable of acquiring the initial access information of the terminal. In some embodiments, the radio resources on which the initial access information is based may be pre-configured to the terminal in accordance with the manner described in any of the embodiments above.

[0132] The access confirmation unit 833 can transmit downlink data via a C-RNTI-scrambled PDCCH or PDSCH. In some embodiments, the access confirmation unit can also send access confirmation information to the terminal. In some embodiments, when downlink data transmission is required, the network-side equipment of the NTN target cell can skip the step of sending access confirmation information to the terminal.

[0133] Such NTN network-side equipment enables RACH-less handover of NTN terminals, simplifies the communication process for NTN terminal handover, overcomes the latency impact caused by satellite service links and feeder links, reduces the probability of handover failure, and improves handover efficiency; it supports sending downlink data to the terminal directly through C-RNTI scrambled PDCCH / PDSCH, reducing signaling interaction while improving the real-time performance of data transmission.

[0134] In some embodiments, the network-side device of an NTN may simultaneously possess the following features: Figure 7 , Figure 8 The unit in the illustrated embodiment thus has the capability to simultaneously serve as a network-side device for both the source and target cells, facilitating flexible switching of the terminal between different cells.

[0135] A schematic diagram of the structure of an embodiment of the network device disclosed herein is shown below. Figure 9 As shown, the network device includes a memory 901 and a processor 902. The memory 901 can be a disk, flash memory, or any other non-volatile storage medium. The memory stores instructions in the corresponding embodiments of the terminal handover method described above. The processor 902 is coupled to the memory 901 and can be implemented as one or more integrated circuits, such as a microprocessor or microcontroller. The processor 902 executes the instructions stored in the memory, simplifying the communication process for NTN terminal handover, overcoming the latency effects of satellite service links and feeder links, reducing the probability of handover failure, and improving handover efficiency.

[0136] In one embodiment, it can also be as follows: Figure 10As shown, network device 1000 includes memory 1001 and processor 1002. Processor 1002 is coupled to memory 1001 via BUS bus 1003. Network device 1000 can also be connected to external storage device 1005 via storage interface 1004 to access external data, and can also be connected to a network or another computer system (not shown) via network interface 1006. Further details are omitted here.

[0137] In this embodiment, by storing data instructions in the memory and then processing the instructions by the processor, the communication process of NTN terminal handover can be simplified, the time delay caused by the satellite service link and the power supply link can be overcome, the probability of handover failure can be reduced, and the handover efficiency can be improved.

[0138] In another embodiment, a computer-readable storage medium stores computer program instructions that, when executed by a processor, implement the steps of the method in the corresponding embodiment of the terminal switching method. Those skilled in the art will understand that embodiments of this disclosure can be provided as methods, apparatus, 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.

[0139] Schematic diagrams of some embodiments of the NTN network-side system 1100 disclosed herein are shown below. Figure 11 As shown.

[0140] The first network-side device 1120 can perform any of the terminal handover methods mentioned above on the source cell side.

[0141] The second network-side device 1130 can execute any of the terminal handover methods on the target cell side mentioned above.

[0142] In such an NTN network-side system, when the network-side equipment sends a RACH-less handover command to the terminal, it can provide auxiliary information to enable the terminal to calculate the TA compensation value applicable to NTN. Based on the current technology, the terminal can autonomously calculate the TA compensation value in a timely manner and perform RACH-less handover by combining the auxiliary information. This simplifies the communication process of NTN terminal handover, overcomes the time delay caused by satellite service links and feeder links, reduces the probability of handover failure, and improves handover efficiency.

[0143] In some embodiments, each network-side device in the network-side system of NTN may simultaneously possess the capability to execute any one of the terminal handover methods on the source cell side mentioned above, and to execute any one of the terminal handover methods on the target cell side mentioned above, thereby facilitating flexible handover of terminals between cells.

[0144] Schematic diagrams of some embodiments of the NTN system disclosed herein are shown below. Figure 12 As shown.

[0145] Terminal 1210 can execute any of the methods described above that are executed by the terminal.

[0146] Network-side devices 1221 and 1222, wherein at least one network-side device (e.g., source satellite 1221) is capable of executing any terminal handover method on the source cell side of the terminal handover mentioned above, and at least one network-side device (e.g., target satellite 1222) is capable of executing any terminal handover method on the target cell side of the terminal handover mentioned above. In some embodiments, each network-side device may support at least one cell, and the network-side device may simultaneously support devices acting as both source and target cells to execute terminal handover methods.

[0147] In such an NTN system, when the network-side equipment sends a RACH-less handover command to the terminal, it can provide auxiliary information to enable the terminal to calculate the TA compensation value applicable to NTN. Based on the current technology, the terminal can autonomously calculate the TA compensation value in a timely manner and perform RACH-less handover by combining the auxiliary information. This simplifies the communication process of NTN terminal handover, overcomes the time delay caused by satellite service links and feeder links, reduces the probability of handover failure, and improves handover efficiency.

[0148] 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 will 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. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0149] 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 function specified in one or more boxes.

[0150] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment 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.

[0151] This concludes the detailed description of the present disclosure. To avoid obscuring the concept of the disclosure, some details known in the art have not been described. Those skilled in the art will fully understand how to implement the technical solutions disclosed herein based on the above description.

[0152] The methods and apparatus of this disclosure may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of this disclosure are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, this disclosure may also be implemented as a program recorded on a recording medium, the program including machine-readable instructions for implementing the methods according to this disclosure. Thus, this disclosure also covers recording media storing programs for performing the methods according to this disclosure.

[0153] It should be noted that the terms "first," "second," etc., used in the specification, claims, and drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and not to limit them; although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this disclosure or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of this disclosure, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in this disclosure.

Claims

1. A terminal handover method, comprising: A terminal located in a non-terrestrial network receives a no-random-access-channel handover instruction, which includes timing advance compensation auxiliary information. The terminal determines the timing advance compensation value based on the timing advance compensation auxiliary information; The terminal initiates a handover to the non-terrestrial network based on the timing advance compensation value; The terminal obtains downlink data through a physical downlink control channel or a physical downlink shared channel scrambled with a temporary identifier of the cell's wireless network, and the terminal determines that the access is successful based on the downlink data.

2. The terminal handover method according to claim 1, wherein, The timing advance compensation auxiliary information includes ephemeris information.

3. The terminal handover method according to claim 2, wherein, The timing advance compensation auxiliary information also includes power supply link TA compensation information.

4. The terminal handover method according to claim 1, wherein, The no-random-access-channel-switching instruction also includes pre-allocated time-frequency resource configuration information. The terminal switching method further includes: the terminal storing the time and frequency resource configuration information.

5. The terminal handover method according to claim 1, further comprising: The terminal obtains and stores the pre-allocated time and frequency resource configuration information through wireless resource control information.

6. The terminal handover method according to claim 4 or 5, wherein, The terminal sends initial access information to the non-terrestrial network based on the timing advance compensation value, including: Once the terminal determines the timing advance compensation value, it sends initial access information to the non-terrestrial network based on the stored time-frequency resource configuration information and the timing advance compensation value.

7. The terminal handover method according to claim 1, further comprising: The terminal receives dynamic authorization information from the target cell via downlink control information; The terminal sends initial access information to the non-terrestrial network based on the timing advance compensation value, including: After receiving the dynamic authorization information, the terminal sends initial access information to the non-terrestrial network based on the timing advance compensation value.

8. The terminal handover method according to claim 3, wherein, The terminal determines the timing advance compensation value based on the timing advance compensation auxiliary information, including: The timing advance compensation value of the power supply circuit is determined based on the timing advance compensation information of the power supply link. Determine the timing advance compensation value for a specific user's device based on the ephemeris information; The timing advance compensation value is determined based on the timing advance compensation value of the power supply circuit and the timing advance compensation value of the specific user equipment.

9. The terminal handover method according to claim 8, wherein, The terminal determining the timing advance compensation value based on the timing advance compensation auxiliary information also includes: the terminal determining the timing advance compensation measurement value.

10. The terminal handover method according to claim 9, wherein, The step of determining the timing advance compensation value based on the timing advance compensation value of the power supply circuit and the timing advance compensation value of the specific user equipment includes: The timing advance compensation value is determined based on the timing advance compensation value of the power supply circuit and the timing advance compensation value of the specific user equipment, combined with the timing advance compensation measurement value, timing advance offset, and unit time length.

11. The terminal handover method according to claim 9, wherein, The determination of the timing advance compensation measurement value includes: when the source cell and the target cell correspond to the same satellite, the timing advance compensation measurement value is the same as that of the source cell.

12. The terminal handover method according to claim 9, wherein, The determination of the timing advance compensation measurement value includes: when the satellites corresponding to the source cell and the target cell are different, the timing advance compensation measurement value is a predetermined value.

13. The terminal handover method according to claim 1, further comprising: The terminal receives access confirmation information and determines that the access was successful based on the access confirmation information.

14. The terminal handover method according to claim 13, wherein, The access confirmation information is carried through the link layer control element.

15. A terminal handover method, comprising: The network-side equipment of the non-terrestrial network sends handover preparation information to the target cell for the terminal handover. The network-side device sends a no-random-access-channel handover instruction to the terminal. The no-random-access-channel handover instruction includes timing advance compensation auxiliary information. The timing advance compensation auxiliary information is used to determine the timing advance compensation value. The timing advance compensation value is used by the terminal to initiate a handover to the target cell of the non-terrestrial network. Whether the handover is successful is determined based on the downlink data obtained by the terminal. The downlink data is obtained through the physical downlink control channel or physical downlink shared channel scrambled by the cell radio network temporary identifier.

16. The terminal handover method according to claim 15, wherein, The no-random-access-channel-switching instruction also includes time-frequency resource configuration information pre-allocated to the terminal.

17. The terminal handover method according to claim 15, further comprising: The pre-allocated time and frequency resource configuration information is sent to the terminal via wireless resource control information.

18. The terminal handover method according to claim 15, further comprising: Receive dynamic authorization information from the target cell; The dynamic authorization information is sent to the terminal via downlink control information.

19. A terminal handover method, comprising: The network-side equipment of the non-terrestrial network obtains handover preparation information from the source cell of the terminal handover; The network-side device receives a handover initiated by the terminal based on a timing advance compensation value, wherein the timing advance compensation value is determined by the terminal according to the timing advance compensation auxiliary information sent by the source cell; Downlink data is transmitted through the physical downlink control channel or physical downlink shared channel scrambled by the temporary identifier of the cell wireless network.

20. The terminal handover method according to claim 19, further comprising: Send access confirmation information to the terminal.

21. The terminal handover method according to claim 20, wherein, The access confirmation information is carried through the link layer control element.

22. The terminal handover method according to claim 19, further comprising: After receiving the handover preparation information, the network-side device generates dynamic authorization information for the terminal. The dynamic authorization information is sent to the source cell.

23. A terminal, comprising: The information acquisition unit is configured to receive a no-random access channel handover instruction from a source cell of a non-terrestrial network, wherein the no-random access channel handover instruction includes timing advance compensation auxiliary information. The compensation value determination unit is configured to determine a timing advance compensation value based on the timing advance compensation auxiliary information. The access unit is configured to initiate a handover to the target cell of the non-terrestrial network based on the timing advance compensation value. The information acquisition unit is further configured to acquire downlink data through a physical downlink control channel or a physical downlink shared channel scrambled by a temporary identifier of the cell wireless network, wherein the terminal determines that the access is successful based on the downlink data.

24. The terminal according to claim 23, wherein, The timing advance compensation auxiliary information includes ephemeris information and power supply link timing advance compensation information.

25. The terminal according to claim 23, wherein, The no-random-access-channel-switching instruction also includes pre-allocated time-frequency resource configuration information. The information acquisition unit is also configured to store the time-frequency resource configuration information.

26. The terminal according to claim 23, wherein, The information acquisition unit is also configured to acquire and store pre-allocated time-frequency resource configuration information through radio resource control information.

27. The terminal according to claim 25 or 26, wherein, The access unit is configured to send initial access information to the non-terrestrial network based on the timing advance compensation value after the compensation value determination unit determines the timing advance compensation value, according to the stored time and frequency resource configuration information.

28. The terminal according to claim 23, wherein, The information acquisition unit is also configured to receive dynamic authorization information of the target cell via downlink control information; The access unit is configured to send initial access information to the non-terrestrial network based on the timing advance compensation value after receiving the dynamic authorization information.

29. A network-side device for a non-terrestrial network, comprising: The handover preparation interaction unit is configured to send handover preparation information to the target cell for the terminal to hand over; The information sending unit is configured to send a handover instruction without random access channel to the terminal. The handover instruction includes timing advance compensation auxiliary information, which is used to determine a timing advance compensation value. The timing advance compensation value is used by the terminal to initiate a handover to the target cell of the non-terrestrial network. Whether the handover is successful is determined based on downlink data obtained by the terminal. The downlink data is obtained through a physical downlink control channel scrambled with a cell radio network temporary identifier or a physical downlink shared channel.

30. The network-side device according to claim 29, wherein, The no-random-access-channel-switching instruction also includes time-frequency resource configuration information pre-allocated to the terminal.

31. The network-side device according to claim 29, wherein, The information sending unit is also configured to send pre-allocated time-frequency resource configuration information to the terminal via radio resource control information.

32. The network-side device according to claim 29, wherein, The handover preparation interaction unit is also configured to receive dynamic authorization information from the target cell; The information sending unit is also configured to send the dynamic authorization information to the terminal via downlink control information.

33. A network-side device for a non-terrestrial network, comprising: The handover preparation unit is configured to acquire handover preparation information from the source cell from which the terminal is handing over; Access information receiving unit is configured to receive handover initiated by terminal based on timing advance compensation value, wherein the timing advance compensation value is determined by terminal according to timing advance compensation auxiliary information sent by source cell; The access confirmation unit is configured to send downlink data through a physical downlink control channel or a physical downlink shared channel scrambled with a temporary identifier of the cell radio network.

34. The network-side device according to claim 33, wherein, The access confirmation unit is also configured to send access confirmation information to the terminal.

35. The network-side device according to claim 33, wherein, The handover preparation unit is further configured to generate dynamic authorization information for the terminal after receiving the handover preparation information, and send the dynamic authorization information to the source cell.

36. A network device, comprising: Memory; as well as A processor coupled to the memory, the processor being configured to execute the method as described in any one of claims 1 to 22 based on instructions stored in the memory.

37. A computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the steps of the method according to any one of claims 1 to 22.

38. A network-side system for a non-terrestrial network, comprising: A first network-side device is configured to perform the method according to any one of claims 15 to 18; and The second network-side device is configured to perform the method described in any one of claims 19 to 22.

39. A non-terrestrial network system, comprising: The terminal is configured to perform the method described in any one of claims 1 to 14; and A network-side device, wherein at least one network-side device is configured to perform the method according to any one of claims 15 to 18; At least one network-side device is configured to perform the method according to any one of claims 19-22.

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