Communication method and device

Abstract

The invention provides a communication method and device, relates to the technical field of communication, and is used for solving the problem that in communication of a non-land network, a terminal measures all candidate cells configured by a network, measurement redundancy exists, and consequently energy consumption of the terminal is wasted. The method comprises: a network device determining at least one candidate cell, and sending first indication information to a terminal, the first indication information being used for indicating a condition for the terminal to execute measurement on the at least one candidate cell.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0002] In non-terrestrial networks (NTN) communications, non-terrestrial network devices including satellites, high altitude platform stations (HAPS) devices, etc. can be used to provide communication services for terminals. In NTN, the terminal will perform cell switching due to the high-speed movement of non-terrestrial network devices.

[0003] In the existing handover process, the network equipment can configure multiple candidate cells for the terminal, and the terminal can measure multiple candidate cells, determine the target cell and access it to complete the handover. For NTN communication, considering the periodic high-speed movement of non-terrestrial network equipment, the candidate cells generally cover the terminal equipment in sequence, that is, the candidate cells generally do not provide coverage for the terminal at the same time. The terminal switches to the target cell in the order in which the non-terrestrial network equipment provides coverage for the terminal.

[0004] Therefore, in NTN, if the network device configures multiple candidate cells for the terminal, and the terminal measures all the configured candidate cells, invalid measurements will be made, thereby causing energy waste of the terminal. Summary of the invention

[0005] The present application provides a communication method and device, which solves the problem that a terminal measures all configured candidate cells, resulting in waste of terminal energy.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] In a first aspect, a communication method is provided, the method comprising: determining at least one candidate cell, and sending first indication information to a terminal, wherein the first indication information is used to indicate a condition for the terminal to perform measurement on the at least one candidate cell.

[0008] By adopting the communication method provided in the present application, the network device indicates to the terminal the condition for performing measurement of at least one candidate cell, so that the terminal can start measurement of the candidate cell that meets the measurement execution condition among the at least one candidate cell, thereby avoiding the terminal from measuring all configured candidate cells and solving the problem of energy waste caused by invalid measurement.

[0009] In one implementation, the first indication information is used to indicate the time information for starting measurement of one or more candidate cells in the at least one candidate cell. The network device may indicate the time information for starting measurement of the candidate cells to the terminal, so that the terminal may determine the start time for performing measurement on different candidate cells based on the time information, thereby avoiding the problem of terminal energy waste caused by the terminal measuring all candidate cells and improving the flexibility of the indication.

[0010] In one implementation, the time for starting measurement on each candidate cell is not earlier than the coverage start time of the candidate cell. That is, the moment when the terminal starts measuring each candidate cell should be later than the coverage start time of the candidate cell for the terminal, or the coverage start time of the candidate cell for the terminal can be used as the moment for starting measurement on the candidate cell, so as to avoid the terminal starting measurement on a candidate cell that does not provide service.

[0011] In one implementation, the first indication information includes Coordinated Universal Time (UTC) information for starting measurement of the one or more candidate cells.

[0012] In one implementation, the first indication information includes the coverage start time of the one or more candidate cells. The terminal can autonomously determine the time to start measuring the candidate cell according to the coverage start time of the candidate cell, thereby avoiding invalid measurement of the candidate cell.

[0013] In one implementation, the first indication information is used to instruct the terminal to determine to start measurement of the one or more candidate cells according to the distance or angle between the terminal and the reference point corresponding to the one or more candidate cells in the at least one candidate cell. In the above implementation, the distance or angle value related to the satellite corresponding to the candidate cell can be used as a judgment condition for performing measurement on the candidate cell, thereby avoiding invalid measurement of the candidate cell and improving the flexibility of the indication.

[0014] In one embodiment, the method further includes: sending a first threshold to the terminal, the first threshold is used to indicate: when the distance between the terminal and the reference point corresponding to the candidate cell satisfies the distance range corresponding to the first threshold, the measurement of the candidate cell is started; or sending a second threshold to the terminal, the second threshold is used to indicate: when the angle between the terminal and the reference point corresponding to the candidate cell satisfies the angle range corresponding to the second threshold, the measurement of the candidate cell is started. Wherein, by setting a threshold value for the distance or angle for starting the measurement of the candidate cell, when performing cell switching, the distance or angle value related to the satellite corresponding to the candidate cell is calculated, and compared with the set distance threshold or angle threshold to determine whether to start the measurement of the candidate cell, thereby improving the flexibility of the indication.

[0015] In one implementation, the first threshold or the second threshold is carried in the first indication information, or in a Radio Resource Control (RRC) reconfiguration message.

[0016] In one implementation, the first indication information includes location information of the reference point.

[0017] In one implementation, the first indication information further includes ephemeris information and a reference time of the ephemeris information.

[0018] In one implementation, the first indication information is used to instruct the terminal to start measurement only on one or more candidate cells in the next cell handover.

[0019] In one implementation, the first indication information is carried in the RRC reconfiguration message.

[0020] In one implementation, the method may be applied to NTN communications.

[0021] In a second aspect, a communication method is provided, which is applied to a terminal, and the method includes: receiving first indication information from the network device, where the first indication information is used to indicate a condition for the terminal to perform measurement on at least one candidate cell.

[0022] In one implementation, the first indication information is used to indicate time information for starting measurement of one or more candidate cells among the at least one candidate cell.

[0023] In one implementation, the time for starting measurement of each candidate cell is no earlier than the coverage start time of the candidate cell.

[0024] In one implementation, the first indication information includes UTC information for starting measurement of the one or more candidate cells.

[0025] In one implementation, the first indication information includes coverage start time of the one or more candidate cells.

[0026] In one implementation, the first indication information is used to instruct the terminal to determine to start measurement of the one or more candidate cells according to the distance or angle between reference points corresponding to the one or more candidate cells in the at least one candidate cell.

[0027] In one embodiment, the method further includes: sending a first threshold to the terminal, and starting measurement of the candidate cell when the distance between the terminal and the reference point corresponding to the candidate cell satisfies the distance range corresponding to the first threshold; or, sending a second threshold to the terminal, and starting measurement of the candidate cell when the angle between the terminal and the reference point corresponding to the candidate cell satisfies the angle range corresponding to the second threshold.

[0028] In one implementation, the first indication information includes location information of the reference point.

[0029] In one implementation, the first indication information further includes ephemeris information and a reference time of the ephemeris information.

[0030] In one implementation, the first indication information is used to instruct the terminal to start measurement only on one or more candidate cells in the next cell handover.

[0031] In one implementation, the method may be applied to NTN communications.

[0032] In a third aspect, a communication method is provided, which is applied to a network device, and the method includes: determining at least one candidate cell; sending a second indication information to the terminal, wherein the second indication information is used to instruct the terminal to delete the configuration information of the at least one candidate cell and / or the configuration information of the source cell when the secondary cell is switched after switching to the target cell. In the above implementation, the network device can delete the configuration information of the candidate cell and / or the source cell after the cell switching is completed by instructing the terminal, and accordingly, the network device can release the corresponding cell resources, thereby avoiding long-term invalid resource reservation, and can effectively improve resource utilization.

[0033] In one implementation, the second indication information includes a first duration, and the first duration is used to indicate that: when the first duration expires or times out, the configuration information of at least one candidate cell and / or the configuration information of the source cell for the secondary cell switching is deleted.

[0034] In one implementation, the second indication information is used to instruct the terminal to delete the configuration information of the at least one candidate cell and / or the configuration information of the source cell when the secondary cell is switched after performing L1 / L2 triggered mobility (L1 / L2Triggered Mobility, LTM) switching.

[0035] In one embodiment, the method further includes: receiving identification information of at least one candidate cell from the terminal, so that the network device can release resources of the candidate cell according to the received identification information of the candidate cell, thereby improving resource utilization.

[0036] In one embodiment, the method further includes: receiving an indication message of completion of cell switching from the terminal; and releasing resources of at least one candidate cell corresponding to the secondary cell switching of the terminal. That is, after the terminal completes the cell switching, the network device can initiate the release of resources of the candidate cell to improve resource utilization.

[0037] In one embodiment, the method further includes: receiving a request message from the terminal to release candidate cell resources; and releasing resources of at least one candidate cell corresponding to the secondary cell switching of the terminal. The terminal may initiate a resource release request to the network device, so that the network device may release resources for the candidate cell according to the request of the terminal, thereby improving resource utilization.

[0038] In one embodiment, if the network device to which the terminal accesses includes a central unit (CU) and a distributed unit (DU), releasing the resources of the candidate cell corresponding to the secondary cell switching of the terminal specifically includes: the DU sends a release request to the CU to request the release of the resources of the candidate cell; the CU determines to release the resources of the candidate cell based on the release request, and sends a release response to the DU; the DU releases the resources of the candidate cell corresponding to the secondary cell switching of the terminal based on the release response.

[0039] In one implementation, the terminal performs cell switching between multiple candidate cells corresponding to one DU, or performs cell switching between multiple candidate cells corresponding to multiple DUs; wherein the multiple DUs correspond to the same CU.

[0040] In one embodiment, if the network device accessed by the terminal includes a CU and a DU, the resources of the candidate cell corresponding to the secondary cell switching of the terminal are released, specifically including: the CU sends a release request to the CU corresponding to the target cell, requesting the release of the resources of the candidate cell; the CU corresponding to the target cell sends a release request to the DU corresponding to the target cell according to the release request, requesting the release of the resources of the candidate cell; the DU corresponding to the target cell deletes the resources of the candidate cell corresponding to the secondary cell switching of the terminal according to the release request.

[0041] In one implementation, the terminal switches from a source cell corresponding to the CU to a target cell, and the CU corresponding to the target cell is different from the CU.

[0042] In one embodiment, the method may be applied to NTN communications.

[0043] In a fourth aspect, a communication method is provided, which is applied to a terminal, and the method includes: receiving a second indication information from the network device; switching to the target cell; and deleting the configuration information of the source cell when the secondary cell is switched, and / or the configuration information of at least one candidate cell according to the second indication information.

[0044] In one embodiment, the second indication information includes a first duration, and the deletion of the configuration information of the target cell when the secondary cell is switched and at least one candidate cell specifically includes: after the first duration expires or times out, deleting the configuration information of the source cell when the secondary cell is switched, and / or the configuration information of at least one candidate cell.

[0045] In one implementation, the second indication information is used to instruct the terminal to delete the configuration information of the source cell of the secondary cell switching and / or the configuration information of at least one candidate cell after performing the LTM switching.

[0046] In one implementation, the method further includes: sending identification information of at least one candidate cell to the network device, so as to instruct the terminal to delete configuration information of the at least one candidate cell.

[0047] In one implementation, the method may be applied to NTN communications.

[0048] In a fifth aspect, a communication method is provided, which is applied to a network device, and the method includes: determining at least one candidate cell corresponding to the terminal; sending an RRC reconfiguration message to the terminal, the RRC reconfiguration message including first configuration information, wherein the first configuration information includes configuration information of the at least one candidate cell, and the first configuration information corresponding to different terminals is different; broadcasting second configuration information, wherein the second configuration information includes configuration information of some candidate cells in the at least one candidate cell, and the some candidate cells are candidate cells corresponding to the next cell switching performed by the terminal, and the second configuration information corresponding to different candidate cells is different.

[0049] In the above implementation, the network side broadcasts the common configuration information of the candidate cell through a broadcast message, so that when sending the configuration information of the candidate cell to the terminal, it is no longer necessary to send the common configuration information of the candidate cell to each terminal, thereby saving the signaling overhead generated by configuring the candidate cell. Furthermore, when the network side configures the candidate cell for multiple cell switching for the terminal, the current serving cell can only broadcast the common configuration information of the candidate cell for the terminal to perform the next cell switching, thereby reducing the signaling overhead caused by the network device broadcasting the common configuration information of the candidate cell.

[0050] In one embodiment, the method further includes: receiving an indication message of completion of cell switching from the terminal; and releasing resources of at least one candidate cell corresponding to the secondary cell switching of the terminal. After the terminal completes the cell switching, the network device may initiate the release of resources of the candidate cell to improve resource utilization.

[0051] In one implementation, the method further includes: receiving a request message for releasing candidate cell resources from the terminal; and releasing resources of at least one candidate cell corresponding to the secondary cell switching of the terminal.

[0052] In one embodiment, if the network device accessed by the terminal includes a CU and a DU, releasing the resources of the candidate cell corresponding to the secondary cell switching of the terminal specifically includes: the DU sends a release request to the CU to request the release of the resources of the candidate cell; the CU determines to release the resources of the candidate cell based on the release request, and sends a release response to the DU; the DU releases the resources of the candidate cell corresponding to the secondary cell switching of the terminal based on the release response.

[0053] In one implementation, the terminal performs cell switching between multiple candidate cells corresponding to one DU, or performs cell switching between multiple candidate cells corresponding to multiple DUs; wherein the multiple DUs correspond to the same CU.

[0054] In one embodiment, if the network device accessed by the terminal includes a CU and a DU, the resources of the candidate cell corresponding to the secondary cell switching of the terminal are released, specifically including: the CU sends a release request to the CU corresponding to the target cell, requesting the release of the resources of the candidate cell; the CU corresponding to the target cell sends a release request to the DU corresponding to the target cell according to the release request, requesting the release of the resources of the candidate cell; the DU corresponding to the target cell deletes the resources of the candidate cell corresponding to the secondary cell switching of the terminal according to the release request.

[0055] In one implementation, the terminal switches from a source cell corresponding to the CU to a target cell, and the CU corresponding to the target cell is different from the CU.

[0056] In one implementation, the method may be applied to NTN communications.

[0057] In a sixth aspect, a communication method is provided, which is applied to a terminal, and the method comprises: receiving an RRC reconfiguration message from the network device, the RRC reconfiguration message comprising first configuration information, wherein the first configuration information comprises configuration information of at least one candidate cell, and the first configuration information corresponding to different terminals is different; receiving second configuration information broadcast by the network device, wherein the second configuration information comprises configuration information of some candidate cells in the at least one candidate cell, and the some candidate cells are candidate cells corresponding to the next cell switching performed by the terminal, and the second configuration information corresponding to different candidate cells is different.

[0058] In one embodiment, the method further includes: executing cell switching according to the RRC reconfiguration message, switching to the target cell; sending a cell switching completion indication message to the network device, used to instruct the network device to release the resources of at least one candidate cell corresponding to the secondary cell switching of the terminal.

[0059] In one embodiment, the method further includes: performing cell switching according to the RRC reconfiguration message, switching to the target cell; sending a request message for releasing candidate cell resources to the network device, to instruct the network device to release the resources of the candidate cell corresponding to the terminal.

[0060] In one implementation, the method may be applied to NTN communications.

[0061] In the seventh aspect, a communication device is provided, which includes a processing module for determining at least one candidate cell; and a transceiver module for sending first indication information to a terminal, wherein the first indication information is used to indicate the conditions for the terminal to perform measurement on the at least one candidate cell.

[0062] In one implementation, the first indication information is used to indicate time information for starting measurement of one or more candidate cells among the at least one candidate cell.

[0063] In one implementation, the time for starting measurement of each candidate cell is no earlier than the coverage start time of the candidate cell.

[0064] In one implementation, the first indication information includes UTC information for starting measurement of the one or more candidate cells.

[0065] In one implementation, the first indication information includes coverage start time of the one or more candidate cells.

[0066] In one implementation, the first indication information is used to instruct the terminal to determine to start measurement of the one or more candidate cells according to the distance or angle between reference points corresponding to the one or more candidate cells in the at least one candidate cell.

[0067] In one embodiment, the transceiver module is also used to send a first threshold to the terminal, where the first threshold is used to indicate that when the distance between the terminal and the reference point corresponding to the candidate cell satisfies the distance range corresponding to the first threshold, measurement of the candidate cell is started; or, a second threshold is sent to the terminal, where the second threshold is used to indicate that when the angle between the terminal and the reference point corresponding to the candidate cell satisfies the angle range corresponding to the second threshold, measurement of the candidate cell is started.

[0068] In one implementation, the first threshold or the second threshold is carried in the first indication information or the RRC reconfiguration message.

[0069] In one implementation, the first indication information includes location information of the reference point.

[0070] In one implementation, the first indication information further includes ephemeris information and a reference time of the ephemeris information.

[0071] In one implementation, the first indication information is used to instruct the terminal to start measurement only on one or more candidate cells in the next cell handover.

[0072] In one implementation, the first indication information is carried in the RRC reconfiguration message.

[0073] In one implementation, the communication device may be applied to NTN communication.

[0074] In an eighth aspect, a communication device is provided, comprising a transceiver module for receiving first indication information from a network device, wherein the first indication information is used to indicate a condition for a terminal to perform measurement on at least one candidate cell.

[0075] In one implementation, the first indication information is used to indicate time information for starting measurement of one or more candidate cells among the at least one candidate cell.

[0076] In one implementation, the time for starting measurement of each candidate cell is no earlier than the coverage start time of the candidate cell.

[0077] In one implementation, the first indication information includes UTC information for starting measurement of the one or more candidate cells.

[0078] In one implementation, the first indication information includes coverage start time of the one or more candidate cells.

[0079] In one implementation, the first indication information is used to instruct the terminal to determine to start measurement of the one or more candidate cells according to the distance or angle between reference points corresponding to the one or more candidate cells in the at least one candidate cell.

[0080] In one embodiment, the transceiver module is also used to send a first threshold to the terminal, and when the distance between the terminal and the reference point corresponding to the candidate cell satisfies the distance range corresponding to the first threshold, the measurement of the candidate cell is started; or, a second threshold is sent to the terminal, and when the angle between the terminal and the reference point corresponding to the candidate cell satisfies the angle range corresponding to the second threshold, the measurement of the candidate cell is started.

[0081] In one implementation, the first indication information includes location information of the reference point.

[0082] In one implementation, the first indication information further includes ephemeris information and a reference time of the ephemeris information.

[0083] In one implementation, the first indication information is used to instruct the terminal to start measurement only on one or more candidate cells in the next cell handover.

[0084] In one implementation, the communication device may be applied to NTN communication.

[0085] In the ninth aspect, a communication device is provided, which includes a processing module for determining at least one candidate cell; a transceiver module for sending a second indication information to a terminal, wherein the second indication information is used to instruct the terminal to delete the configuration information of the at least one candidate cell switched to the secondary cell and / or the configuration information of the source cell after switching to the target cell.

[0086] In one implementation, the second indication information includes a first duration, and the first duration is used to indicate that: when the first duration expires or times out, the configuration information of at least one candidate cell and / or the configuration information of the source cell for the secondary cell switching is deleted.

[0087] In one implementation, the second indication information is used to instruct the terminal to delete the configuration information of the at least one candidate cell and / or the configuration information of the source cell when the secondary cell is switched after performing L1 / L2 triggered mobility LTM switching.

[0088] In one implementation, the transceiver module is further configured to receive identification information of at least one candidate cell from the terminal.

[0089] In one implementation, the transceiver module is further configured to receive a cell switching completion indication message from the terminal; the device further comprises a processing module configured to release resources of at least one candidate cell corresponding to the secondary cell switching of the terminal.

[0090] In one implementation, the transceiver module is further configured to receive a request message from the terminal for releasing candidate cell resources; the device further comprises a processing module configured to release resources of at least one candidate cell corresponding to the secondary cell switching of the terminal.

[0091] In one embodiment, if the communication device includes a CU and a DU, releasing the resources of the candidate cell corresponding to the secondary cell switching of the terminal specifically includes: the DU sends a release request to the CU to request the release of the resources of the candidate cell; the CU determines to release the resources of the candidate cell based on the release request, and sends a release response to the DU; the DU releases the resources of the candidate cell corresponding to the secondary cell switching of the terminal based on the release response.

[0092] In one implementation, the terminal performs cell switching between multiple candidate cells corresponding to one DU, or performs cell switching between multiple candidate cells corresponding to multiple DUs; wherein the multiple DUs correspond to the same CU.

[0093] In one embodiment, if the communication device includes a CU and a DU, releasing the resources of the candidate cell corresponding to the secondary cell switching of the terminal specifically includes: the CU sends a release request to the CU corresponding to the target cell, requesting the release of the resources of the candidate cell; the CU corresponding to the target cell sends a release request to the DU corresponding to the target cell according to the release request, requesting the release of the resources of the candidate cell; the DU corresponding to the target cell deletes the resources of the candidate cell corresponding to the secondary cell switching of the terminal according to the release request.

[0094] In one implementation, the terminal switches from a source cell corresponding to the CU to a target cell, and the CU corresponding to the target cell is different from the CU.

[0095] In one implementation, the communication device may be applied to NTN communication.

[0096] In the tenth aspect, a communication device is provided, which includes a transceiver module for receiving a second indication information from the network device; a processing module for switching to a target cell; the processing module is also used to delete the configuration information of the source cell when the secondary cell is switched, and / or the configuration information of at least one candidate cell according to the second indication information.

[0097] In one implementation, the second indication information includes a first duration, and the processing module is specifically configured to delete the configuration information of the source cell of the secondary cell switching and / or the configuration information of at least one candidate cell when the first duration expires or times out.

[0098] In one implementation, the second indication information is used to instruct the terminal to delete the configuration information of the source cell of the secondary cell switching and / or the configuration information of at least one candidate cell after performing the LTM switching.

[0099] In one implementation, the transceiver module is further configured to send identification information of at least one candidate cell to the network device, so as to instruct the terminal to delete configuration information of the at least one candidate cell.

[0100] In one implementation, the communication device may be applied to NTN communication.

[0101] In the eleventh aspect, a communication device is provided, which includes a processing module for determining at least one candidate cell corresponding to the terminal; a transceiver module for sending an RRC reconfiguration message to the terminal, the RRC reconfiguration message including first configuration information, wherein the first configuration information includes configuration information of the at least one candidate cell, and the first configuration information corresponding to different terminals is different; the transceiver module is also used to broadcast second configuration information, wherein the second configuration information includes configuration information of some candidate cells in the at least one candidate cell, and the some candidate cells are candidate cells corresponding to the next cell switching performed by the terminal, and the second configuration information corresponding to different candidate cells is different.

[0102] In one implementation, the transceiver module is further configured to receive a cell switching completion indication message from the terminal; and release resources of at least one candidate cell corresponding to the secondary cell switching of the terminal.

[0103] In one implementation, the transceiver module is further configured to receive a request message from the terminal for releasing candidate cell resources; and release resources of at least one candidate cell corresponding to the secondary cell switching of the terminal.

[0104] In one embodiment, if the communication device includes a CU and a DU, releasing the resources of the candidate cell corresponding to the secondary cell switching of the terminal specifically includes: the DU sends a release request to the CU to request the release of the resources of the candidate cell; the CU determines to release the resources of the candidate cell based on the release request, and sends a release response to the DU; the DU releases the resources of the candidate cell corresponding to the secondary cell switching of the terminal based on the release response.

[0105] In one implementation, the terminal performs cell switching between multiple candidate cells corresponding to one DU, or performs cell switching between multiple candidate cells corresponding to multiple DUs; wherein the multiple DUs correspond to the same CU.

[0106] In one embodiment, if the communication device includes a CU and a DU, releasing the resources of the candidate cell corresponding to the secondary cell switching of the terminal specifically includes: the CU sends a release request to the CU corresponding to the target cell, requesting the release of the resources of the candidate cell; the CU corresponding to the target cell sends a release request to the DU corresponding to the target cell according to the release request, requesting the release of the resources of the candidate cell; the DU corresponding to the target cell deletes the resources of the candidate cell corresponding to the secondary cell switching of the terminal according to the release request.

[0107] In one implementation, the terminal switches from a source cell corresponding to the CU to a target cell, and the CU corresponding to the target cell is different from the CU.

[0108] In one implementation, the communication device may be applied to NTN communication.

[0109] In the twelfth aspect, a communication device is provided, which includes a transceiver module, and is used to receive an RRC reconfiguration message from the network device, the RRC reconfiguration message including first configuration information, wherein the first configuration information includes configuration information of at least one candidate cell, and the first configuration information corresponding to different terminals is different; receive second configuration information broadcast by the network device, wherein the second configuration information includes configuration information of some candidate cells in the at least one candidate cell, and the some candidate cells are candidate cells corresponding to the terminal performing the next cell switching, and the second configuration information corresponding to different candidate cells is different.

[0110] In one embodiment, the device also includes a processing module for performing cell switching according to the RRC reconfiguration message and switching to the target cell; the transceiver module is also used to send an indication message of cell switching completion to the network device, used to instruct the network device to release the resources of at least one candidate cell corresponding to the secondary cell switching of the terminal.

[0111] In one embodiment, the device also includes a processing module for performing cell switching according to the RRC reconfiguration message and switching to the target cell; the transceiver module is also used to send a request message for releasing candidate cell resources to the network device, instructing the network device to release the resources of the candidate cell corresponding to the terminal.

[0112] In one implementation, the communication device may be applied to NTN communication.

[0113] In the thirteenth aspect, a communication device is provided, comprising: one or more processors and one or more memories; the one or more memories are coupled to the one or more processors, the one or more memories are used to store computer program codes, the computer program codes include computer instructions, and when the one or more processors execute the computer instructions, the communication device executes a method as described in any one of the first to sixth aspects above.

[0114] In a fourteenth aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer-executable instructions, and when the computer-executable instructions are called by the computer, the computer is used to cause the computer to execute any one of the methods described in the first to sixth aspects above.

[0115] In a fifteenth aspect, a computer program product comprising instructions is provided, and when the computer program product is run on a computer, the computer is caused to execute the method described in any one of the first to sixth aspects above.

[0116] In the sixteenth aspect, a chip is provided, wherein the chip is coupled to a memory and is used to read and execute program instructions stored in the memory to implement a method as described in any one of the first to sixth aspects above.

[0117] It can be understood that any one of the communication devices, computer-readable storage media, computer program products or chips provided in the above-mentioned seventh aspect to the sixteenth aspect can be implemented by the corresponding method provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding method provided above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0118] Figure 1 An architecture diagram of a communication system provided in an embodiment of the present application;

[0119] Figure 2 A system architecture diagram of an access network device provided in an embodiment of the present application;

[0120] Figure 3 A communication system architecture diagram of NTN communication provided in an embodiment of the present application;

[0121] Figure 4 A communication system architecture diagram of another NTN communication provided in an embodiment of the present application;

[0122] Figure 5 A schematic diagram of a satellite operating mode provided in an embodiment of the present application;

[0123] Figure 6 A schematic diagram of another working mode of a satellite provided in an embodiment of the present application;

[0124] Figure 7 A schematic diagram of a cell switching process provided in an embodiment of the present application;

[0125] Figure 8 A schematic diagram of a LTM switching process provided in an embodiment of the present application;

[0126] Fig. 9A A schematic diagram of sequential cell switching provided in an embodiment of the present application;

[0127] Fig. 9B A schematic diagram of a conditional switching process provided in an embodiment of the present application;

[0128] Figure 10-12 A communication method according to an embodiment of the present invention is provided. Figures 1 to 3 ;

[0129] Fig.13A schematic diagram of the structure of a communication device provided in an embodiment of the present application;

[0130] Fig.14 A schematic diagram of the structure of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0131] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0132] First, the implementation environment and application scenarios of the embodiments of the present application are briefly introduced.

[0133] The technical solution of the embodiment of the present application can be applied to the NTN communication system. The technical solution in the present application will be described below in conjunction with the accompanying drawings.

[0134] NTN communication is a deployment scenario of non-terrestrial networks including satellite systems or high altitude platform stations (HAPS), which realize wireless communication services with the help of the wide area coverage capability of non-terrestrial network devices such as satellites. The non-terrestrial network devices described in this application can also be referred to as aerial network devices, such as satellites, HAPS devices, drone devices, etc., which can be deployed in the air, without limitation. In this application, satellites are used as examples of aerial network devices.

[0135] To facilitate understanding of the embodiments of the present application, first Figure 1 The following describes a communication system applicable to an embodiment of the present application. Figure 1 FIG. 1 shows a schematic diagram of an architecture of a communication system applicable to an embodiment of the present application. Figure 1 As shown, the communication system 100 may include at least one network device, such as Figure 1 The network device 110 shown; the communication system 100 may also include at least one terminal device, such as Figure 1 The network device 110 and the terminal device 120 can communicate via a wireless link. Figure 1 As shown, the network device 110 can manage cell 1 and cell 2, and provide communication services to terminal devices located in cell 1 and cell 2. When a terminal device is located in the overlapping area of ​​cell 1 and cell 2, a switching process as described in the embodiment of the present application will occur. The switching in the present application refers to the process of moving the terminal device in the service state and changing the service cell.

[0136] It should be understood that the network equipment in the communication system 100 may include access network equipment, which refers to a radio access network (RAN) node (or device) that accesses a terminal to a wireless network, such as a base station.

[0137] Some examples of RAN nodes are: evolved Node B (gNB), transmission reception point (TRP), evolved Node B (eNB), radio network controller (RNC), Node B (NB), base station controller (BSC), base transceiver station (BTS), home base station (e.g., home evolved Node B, or home Node B, HNB), base band unit (BBU), etc. In addition, RAN nodes may also be devices that perform base station functions in device-to-device (D2D) communication, vehicle to everything (V2X) communication, machine-type communication (MTC), satellites, or base stations in future communication systems, etc., without limitation.

[0138] In addition, in a network structure, the access network device may include a central unit (CU) node and / or a distributed unit (DU) node. Figure 2 As shown, in the gNB including CU node and DU node, the functions of some protocol layers are placed in the CU for centralized control, and the functions of the remaining part or all of the protocol layers are distributed in the DU, which is centrally controlled by the CU. Furthermore, the CU can also be divided into the control plane (CU-CP) and the user plane (CU-UP). Among them, the CU-CP is responsible for the control plane function, mainly including RRC and PDCP corresponding to the control plane, namely PDCP-C. CU-UP is responsible for the user plane function, which may include SDAP and PDCP corresponding to the user plane, namely PDCP-U. Among them, CU-CP and CU-UP are connected through the E1 interface. CU-CP represents the gNB connected to the core network through the NG interface. The control plane is connected to DU through the F1 interface, namely F1-C. CU-UP is connected to DU through the F1 interface user plane, namely F1-U. Another possible implementation is that PDCP-C is also in CU-UP.

[0139] In different systems, CU (including CU-CP or CU-UP) or DU may have different names, but those skilled in the art can understand their meanings. For example, in an open radio access network (O-RAN) system, CU may also be called O-CU (open CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, and CU-UP may also be called O-CU-UP.

[0140] The terminal device in the communication system 100 may also be referred to as a terminal, a user unit, a user station, a mobile station, a mobile station, a remote station, a remote terminal device, a mobile device, a user equipment (UE), a wireless communication device, a user agent or a user device. The terminal device provided in the present application may be applied to various communication scenarios, for example, D2D communication, V2X communication, MTC, Internet of things (IOT), virtual reality (VR), augmented reality (AR), industrial control, self driving, telemedicine, smart grid, smart furniture, smart office, smart wear, smart transportation, smart city, etc. The terminal device may be a mobile phone, a tablet computer (pad), a computer with wireless transceiver function, a wearable device, aerospace equipment, drone equipment, etc. In the embodiment of the present application, the chip used in the above-mentioned device may also be referred to as a terminal device.

[0141] In addition, if Figure 1 As shown, the communication system may further include a gateway 130. The gateway 130 may provide communication services for network devices such as satellite beam coverage areas. The gateway 130 may be used to connect the base station to the core network. In addition, the gateway 130 may serve as a management, switching and control center for the non-terrestrial communication system, responsible for signal access, user authentication management, service admission control and data exchange of the NTN system.

[0142] Below Figure 1 The communication system shown is applied to the NTN communication scenario as an example to introduce the implementation environment of the present application in detail.

[0143] The NTN system may include at least one air network device, such as Figure 1 The network device 110 shown is an airborne network device, for example, the network device 110 may be a satellite; the NTN system may also include at least one terminal device, such as Figure 1 The terminal device 120 is shown.

[0144] Among them, the satellite can be an artificial earth satellite that serves as a radio communication relay station. The satellite realizes radio communication between satellite communication earth stations or between earth stations and spacecraft by forwarding radio signals. Satellites can transmit information such as telephone, telegraph, fax, data and television.

[0145] According to the working mode of the satellite, the satellite can work in the transparent transmission mode or the regeneration mode. Among them, when the satellite works in the transparent transmission mode, the satellite can act as a relay forwarding device to forward the signals of other network devices or terminal devices 120, and can be used as an enhancement of ground network coverage. The role of the satellite is wireless frequency filtering, frequency conversion and amplification, that is, the satellite mainly acts as an L1 (layer 1) forwarding function to regenerate the physical layer signal, and does not have other higher protocol layer functions. Figure 3 As shown, the terminal and the base station can be transparently forwarded via satellite to achieve communication with the 5G core network and data network.

[0146] In one scenario, when the satellite operates in the transparent transmission mode, the satellite can be used as a relay forwarding device between the gateway 130 and the terminal device 120 to forward communication signals between the gateway 130 and the terminal device 120 .

[0147] When the satellite operates in the regeneration mode, the satellite has signal processing capability; it can be understood that the satellite has the processing function of a base station and can send signals to other network devices or the terminal device 120, thereby providing communication services to the terminal device 120. Figure 4 As shown, the terminal establishes wireless communication with the satellite through the Uu port to achieve communication with the 5G core network and data network.

[0148] In addition, when the satellite works in the regeneration working mode, it can also be divided into a regeneration satellite without an inter-satellite link and a regeneration satellite with an inter-satellite link according to whether there is an inter-satellite link (ISL) between the satellites. It can be understood that there is an ISL between the satellites, that is, there is an interface between the satellites to directly exchange data. For example, the interface of the inter-satellite link can be an Xn port, and the satellites can exchange data through the Xn port. In addition, in one scenario, the regeneration satellite can have the DU processing function of the base station, and the satellite can serve as a DU node.

[0149] Generally speaking, according to the different altitudes of satellite operating orbits, satellites can be divided into geostationary orbit (GEO) satellites, medium earth orbit (MEO) satellites and low earth orbit (LEO) satellites. Among them, the higher the orbit of the satellite, the larger the coverage area of ​​its corresponding service cell, but the longer the communication delay. Exemplarily, GEO is a synchronous earth satellite orbit, and satellites operating in this orbit are stationary relative to the ground. LEO and MEO are collectively referred to as non-geosynchronous orbits (NGSO), and satellites operating in such orbits move at high speed relative to the ground.

[0150] For NGSO, according to whether the satellite beam moves with the satellite, it can be further divided into earth moving cells and geostationary cells.

[0151] For a mobile cell, the satellite's beam pointing follows the satellite's movement. Therefore, the cell range covered by the satellite's beam moves relative to the ground. Figure 5 As shown in the figure, at time T1, the satellite covers cell 1, and at time T2, the satellite covers cell 2. It can be seen that as the satellite moves at high speed, terminals continue to access the satellite and then exit the connection with the satellite. For NGSO, the high-speed movement of satellites will lead to frequent user switching, and the frequent switching of large-scale users will bring large signaling overhead.

[0152] For geostationary cells, within a certain period of time, the satellite antenna can use its beamforming capability to point the beam to a certain area fixed on the ground (which can be called staring). Therefore, the cell range covered by the satellite beam is fixed relative to the ground. Figure 6 As shown in the figure, satellite 1 covers cell 1 from time T1 to T2. After time T2, satellite 1 ends its gaze on cell 1, and satellite 2 will cover cell 1 for a period of time. Therefore, when the satellite is about to move out of the gazed cell range, all the terminals in cell 1 need to switch to the cell covered by the next satellite, such as the terminal needs to switch from satellite 1 to satellite 2. Similarly, the simultaneous switching of a large number of terminals will bring about a large signaling overhead, and cause a signaling storm, resulting in signaling congestion.

[0153] The handover process of the terminal is usually controlled by the network device, that is, the network device sends a handover message to instruct the terminal which cell to switch to and how to switch. After receiving the handover message, the terminal accesses the target cell according to the content contained in the handover message. Therefore, the network side needs to obtain the identifier of the target cell.

[0154] like Figure 7 As shown, the communication system may include a UE that performs handover, an access network device to which a source cell belongs, namely a source base station, and an access network device to which a target cell belongs, namely a target base station. The specific handover process may include the following steps.

[0155] 701: The source base station sends an RRC reconfiguration message to the UE.

[0156] The RRC reconfiguration message is used to instruct the UE to perform measurement, and may include at least one of the following: measurement object, report configuration, measurement identifier and other parameters.

[0157] 702: The UE sends a measurement report to the source base station.

[0158] The UE performs measurement according to the measurement configuration in the RRC reconfiguration message, generates a measurement report and sends it to the source base station, which is used to report various measurement events to the source base station.

[0159] Among them, steps 701 to 702 are optional.

[0160] 703: The source base station sends a handover request message to the target base station.

[0161] Specifically, the source base station receives the measurement report reported by the UE, determines one or more candidate cells according to the measurement results, and makes a handover decision. Among them, the access network device corresponding to the target cell can be the target base station. When the decision result of the source base station is handover, the source base station can send a handover request message to the target base station.

[0162] 704: The target base station sends a handover confirmation message to the source base station.

[0163] Specifically, the target base station determines whether to allow the UE to access, and if it is determined to allow, sends a handover confirmation message to the source base station. Among them, the handover confirmation message may include the configuration information required for the UE to access the target base station. For example, the configuration information required for the UE to access the target base station may include one or more of the following: target cell ID, encryption algorithm, key, measurement configuration information, system information of the target cell, a new cell radio network temporary identifier (Cell-Radio Network Temporary Identifier, C-RNTI) allocated by the target base station to the UE, a random access channel (random access channel, RACH) resource for accessing the target cell (also referred to as a random access resource, and the following is explained by taking the random access resource as an example), the physical layer configuration parameters corresponding to the target cell, the media access control (media access control, MAC) layer configuration parameters, the radio link control (radio link control, RLC) layer configuration parameters, the packet data convergence protocol (packet data convergence protocol, PDCP) layer configuration parameters, the service data adaptation protocol (service data adaptation protocol, SDAP) layer configuration parameters, the radio resource control (radio resource control, RRC) layer configuration parameters, etc. The random access resource may include one or more of the following: a configuration period of random access, configuration information of a random access format, configuration information of at least one random access opportunity (RACH occasion), configuration information of a preamble code associated with each random access opportunity (e.g., the number of preamble codes and / or index information of the preamble code), etc. Optionally, the configuration information required for the UE to access the target base station may be carried in the form of an RRC message. For example, the target base station generates an RRC reconfiguration message, and the handover confirmation message carries the RRC message.

[0164] Optionally, the source base station and the target base station may be the same base station or different base stations.

[0165] 705: The source base station sends an RRC reconfiguration message to the UE.

[0166] Specifically, after receiving the handover confirmation message sent by the target base station, the source base station sends an RRC reconfiguration message to the UE. The RRC reconfiguration message may include information indicated in the handover confirmation message in step 704, or an RRC reconfiguration message generated by the target base station in step 704. In step 705, the RRC reconfiguration message sent by the source base station to the UE may also be referred to as a handover command.

[0167] The target cell may be one of the one or more candidate cells, or may be a serving cell other than the candidate cells.

[0168] It is understandable that in order to distinguish from the candidate cell, in the embodiment of the present application, the serving cell accessed by the UE after cell switching is referred to as the target cell. This will not be repeated in the subsequent embodiments.

[0169] 706: The UE initiates random access to the target base station.

[0170] Specifically, the UE can initiate a random access request to the target base station (the base station of the target cell) according to the handover command, and successfully access the target base station by interacting with the target base station. In the existing handover process, the UE will disconnect from the source base station, and before successfully accessing the target base station, the UE may have a short interruption in sending and receiving data.

[0171] 707: The UE sends a message indicating that the RRC reconfiguration is completed to the target base station.

[0172] After the UE successfully accesses the target base station, it may send an RRC reconfiguration completion message to the target base station.

[0173] In the above inter-cell handover process, when the terminal moves from the coverage area of ​​one cell to the coverage area of ​​another cell, the terminal can switch the serving cell at a certain moment, and the above cell handover process is based on the L3 measurement results, for example, the target cell selection and decision of the handover are based on the L3 measurement results, and the handover is triggered by RRC signaling, so it can be called the L3 handover process. All processes require complete layer 2 (layer 2, L2) and layer 1 (layer 1, L1) reset, which will introduce more delay and signaling overhead.

[0174] In order to further reduce the switching delay, an L1 / L2 mobility enhancement solution is proposed, namely L1 / L2 triggered mobility (LTM) switching, that is, switching the serving cell by using L1 / L2 signaling to achieve the goals of low latency, low overhead and low data interruption time.

[0175] For the following scenarios: 1. The terminal switches between multiple cells corresponding to a DU, such as intra-gNB DU switching; 2. The terminal switches between multiple cells of different DUs corresponding to a CU, such as inter-gNB DU intra-gNB CU switching; 3. The terminal switches between multiple cells corresponding to different CUs, such as inter gNB CU switching. Similar to L3 switching, in LTM switching, the network device can select the target cell based on the L3 measurement results. The subject that performs the target cell selection can be the gNB-CU. The network device can send the LTM switching configuration information to the UE through the RRC reconfiguration message.

[0176] The difference between LTM switching and L3 switching is that LTM switching is determined and triggered by L1 / L2. For example, the UE reports the L1 measurement results to the gNBDU, and the gNB DU makes a switching decision based on the measurement results and sends a switching command to the UE through the MAC control element (CE). After the LTM switching is completed, the UE can save the configuration information of multiple candidate cells (including the target cell) configured previously, so that when the UE switches to the candidate cell next time, the network device can directly send a switching command without sending the configuration information of the candidate cell again, which can save the switching configuration process and reduce the switching delay.

[0177] In one implementation, for a handover scenario between different cells in the same station, such as Figure 8 As shown, the switching process of LTM may include the following steps.

[0178] 801: UE sends a measurement report to a network device.

[0179] Specifically, the UE may measure all candidate cells configured for it by the network device and generate a measurement report.

[0180] Correspondingly, the network device receives the measurement report, determines to adopt LTM switching according to the measurement report, and triggers candidate cell preparation.

[0181] The network device may specifically be a base station including a CU and a DU. The UE may perform LTM switching between different serving cells corresponding to the base station.

[0182] Among them, step 801 is optional.

[0183] 802: The network device sends an RRC reconfiguration message to the UE.

[0184] Among them, the RRC reconfiguration message may include configuration information of the candidate cell, and there may be one or more candidate cells. In the LTM switching process, these candidate cells are also referred to as LTM candidate cells. Optionally, the configuration information of the candidate cell may include one or more of the following: the cell radio network temporary identifier allocated by the candidate cell to the terminal device, the random access channel for accessing the candidate cell, the identifier of the candidate cell, the physical layer configuration parameters corresponding to the candidate cell, the media access control layer configuration parameters, the radio link control layer configuration parameters, the packet data convergence protocol layer configuration parameters, the service data adaptation protocol layer configuration parameters, the radio resource control layer configuration parameters, etc.

[0185] Optionally, the RRC reconfiguration message also carries an identifier corresponding to the configuration information of the candidate cell.

[0186] 803: The UE sends an RRC reconfiguration completion message to the network device.

[0187] The UE receives the RRC reconfiguration message, saves the configuration information of the candidate cells therein, and sends an RRC reconfiguration completion message to the network device.

[0188] Optionally, the LTM switching process may further include an early synchronization phase, which may specifically include step 804 .

[0189] 804: The UE achieves uplink or downlink synchronization with the candidate cell.

[0190] Specifically, before receiving the handover command (the handover command in the LTM refers to the handover command in step 806), the UE may perform downlink synchronization with the candidate cell.

[0191] Before receiving the handover command, the UE will obtain the timing advance (TA) value corresponding to the candidate cell in advance. The present application does not limit the method by which the UE obtains the timing advance value corresponding to the candidate cell in advance.

[0192] 805: The UE measures the configured candidate cells and reports the L1 measurement result.

[0193] This application does not limit the order of step 804 and step 805.

[0194] 806: The network device determines whether to perform LTM switching according to the L1 measurement result. If LTM switching is to be performed, an LTM switching command is sent to the UE to trigger the execution of the switching.

[0195] The LTM switching command may be a MAC CE, and the MAC CE may carry an identifier of the target cell configuration information. The UE uses the corresponding target cell configuration according to the identifier.

[0196] Optionally, if the UE needs to perform a random access process when switching to the target cell, step 807 may be further included. For example, if the aforementioned step 804 is not performed, that is, the UE does not acquire the TA to achieve synchronization, step 807 may also be included.

[0197] 807: The UE randomly accesses the target cell.

[0198] 808: The UE sends a handover completion indication to the network device of the target cell.

[0199] For example, the UE sends an RRC reconfiguration complete message to the network device to which the target cell belongs. Optionally, the network devices of the source cell and the target cell may be the same, such as Figure 8 As shown; or, the network devices of the source cell and the target cell may also be different, such as network device 1 and network device 2 respectively.

[0200] Optionally, after step 808, the UE may continue to perform steps 804 to 808 based on the configuration in step 802 to switch to other candidate cells. That is, the above LTM process can be applied to the scenario of continuous terminal switching. Fig. 9A As shown in the figure, in the communication scenario of the terrestrial network (TN), the movement of the UE is random, so the order of the continuous switching of the UE is also random, and the network device and the UE cannot know which cell the UE will switch to next. For example, if the UE is currently connected to cell 1, it may switch to cell 2, cell 3 or cell 4 later. The cell to which the UE switches is related to the mobile position of the UE, so each hop switching of the UE is unknown. For example, the UE switches from cell 1 to cell 4. After the switching is completed, the UE can save the configuration information of cell 2 and cell 3. When the UE needs to switch from cell 4 to cell 2 later, the network device does not need to re-send the configuration of cell 2 to the UE. The UE directly measures the candidate cell and reports the measurement results. When the switching conditions are met, the network device directly triggers the switching through the LTM switching command (such as MAC CE). In the scenario of continuous switching, the UE will save the configuration of the candidate cell in the LTM switching process. When the UE needs to switch to the cell that has been switched before or other candidate cells, the network device does not need to send the configuration information of these candidate cells to the UE. It only needs to send the LTM switching command, which can speed up the switching process.

[0201] However, in NTN scenarios, since satellite movement is periodic, terminal switching is usually carried out in a certain order and regularly. Fig. 9AAs shown, the cell switching sequence of the UE can be: cell 1→cell 2→cell 3→cell 4→cell 5→…→cell N→cell 1→cell 2→cell 3→…. It can be seen that multiple candidate cells provide signal coverage for the location range where the UE is located in a certain order, and a candidate cell will re-provide signal coverage for the location range in the next cycle after the coverage ends. Therefore, if the movement of the UE is ignored and only the movement of the satellite is considered, the continuous cell switching in the NTN scenario can be regarded as periodic or regular.

[0202] In one implementation, the cell handover involved in the present application may be a conditional handover (CHO).

[0203] The CHO mechanism is a switching based on CHO trigger condition information (also referred to as CHO execution condition information). The network device to which the source cell belongs (referred to as the source network device) can send CHO configuration information to the terminal device when the communication link quality is good. The CHO configuration information includes CHO trigger condition information corresponding to one or more candidate cells and information of one or more candidate cells.

[0204] The information of the candidate cell may include one or more of the following: a cell radio network temporary identifier allocated by the candidate cell to the terminal device, a random access channel resource (also referred to as a random access resource) for accessing the candidate cell, an index corresponding to the candidate cell (such as a measurement identifier (measID) corresponding to the candidate cell and / or a CHO reconfiguration identifier (CondReconfigId) corresponding to the candidate cell), a cell global identifier (cell global identifier, CGI) of the candidate cell, a physical cell identifier (physical cell identifier, PCI) of the candidate cell, frequency information corresponding to the candidate cell, physical layer configuration parameters corresponding to the candidate cell, MAC layer configuration parameters, RLC layer configuration parameters, PDCP layer configuration parameters, SDAP layer configuration parameters, RRC layer configuration parameters, etc. The random access resource may include one or more of the following: a configuration period of random access, configuration information of a random access format, configuration information of at least one random access opportunity (RACH occasion), configuration information of a preamble code associated with each random access opportunity (e.g., the number of preamble codes and / or index information of the preamble code), etc. The frequency information of the candidate cell may include one or more of the following: the absolute frequency (absoluteFrequencySSB) of the synchronization signal block (SSB), the absolute frequency position (absoluteFrequencyPointA) of the reference resource module (common RB0), the frequency bandwidth list (frequencyBandList), and the subcarrier spacing (SCS) specific carrier list (scs-SpecificCarrierList). The meaning of the above terms can be referred to, for example, the provisions of the protocol or standard of the communication technology.

[0205] The CHO trigger condition information may also be referred to as CHO execution condition information. The CHO trigger condition information is used to indicate the CHO trigger condition of the candidate cell. In this application, the CHO trigger condition information may include one or more of the following:

[0206] 1. Based on signal quality. The signal quality involved in this application is the result of measuring the signal quality or signal energy based on a reference signal (such as SSB, CSI-RS, CS-RS, US-RS or DMRS, etc.). Such as one or more of reference signal received power (reference signal received power, RSRP), reference signal received quality (reference signal received quality, RSRQ), received signal strength indicator (received signal strength indicator, RSSI), and signal to interference plus noise ratio (signal to interference plus noise ratio, SINR). The meaning of the above terms can, for example, refer to the provisions of the protocol or standard of the communication technology. Among them, the CHO trigger condition information may include a CHO trigger event type, a trigger quantity (trigger quantity) and a corresponding threshold value. The CHO trigger event type may include event A3, event A4, event A5, event B1, event B2 or other trigger event types, etc., and specific reference may be made to the provisions of the protocol or standard of the communication technology. The trigger quantity is the signal quality of the cell. Exemplarily, assuming that the CHO trigger event type configured for candidate cell 1 is an A3 event, the trigger quantity is the signal quality of the cell, and the corresponding threshold value is threshold 1, then when the cell signal quality of candidate cell 1 is higher than threshold 1, it can be considered that candidate cell 1 meets the CHO trigger condition, and the candidate cell 1 can be determined as the target cell.

[0207] 2. Based on location information. The CHO trigger condition information may include location information. In one possible implementation, the location information may be the location information of the terminal device on the ground, such as longitude and latitude values, which can be used to determine a certain area or a fixed point. When the geographical location of the terminal device meets the longitude and latitude requirements (such as the terminal device moves to the area or fixed point indicated by the longitude and latitude values), the terminal device can perform switching. In another possible implementation, the location information may include the distance between the terminal device and the location reference point 1 corresponding to the source cell and the distance between the terminal device and the location reference point 2 corresponding to the target cell. For example, the CHO trigger condition information may include a first distance threshold value and a second distance threshold value. When the distance between the terminal device and the location reference point 1 corresponding to the source cell is greater than or equal to the first distance threshold value, and the distance between the terminal device and the location reference point 2 corresponding to the target cell is less than or equal to the second distance threshold value, the UE can perform switching. In another possible implementation, the location information may be global positioning system (GPS) information, timing advance (TA) or other information.

[0208] 3. Based on time information or timer. The CHO trigger condition information may include time information. In one possible implementation, the CHO trigger condition information may be an absolute time, such as a certain moment (such as coordinated universal time (UTC) 12:00), a certain time period (such as UTC 12:00-UTC13:00, or a starting moment and the duration of a time period, etc.). When the absolute time is reached, the terminal device may perform switching. In another possible implementation, the CHO trigger condition information may be a relative time, such as the effective duration of a timer. For example, after the terminal device receives the CHO configuration information, it starts the timer. When the effective duration of the timer is reached, the terminal device may perform switching.

[0209] Optionally, in the present application, at least one of the above three types of CHO trigger condition information can be configured as CHO execution condition information. For example, the CHO execution event type and the corresponding threshold value and absolute time value can be configured as CHO execution condition information. When the absolute time arrives and the signal quality of the corresponding candidate cell meets the conditions, the terminal device can determine the candidate cell as the target cell and perform switching.

[0210] Optionally, one candidate cell may correspond to one or more CHO triggering condition information. The CHO triggering condition information corresponding to different candidate cells may be the same or different.

[0211] For ease of understanding, the following Fig. 9B The handover process of the terminal device based on the CHO mechanism is described by way of example. In this example, the source network device configures two candidate cells for the terminal device, and the two candidate cells are managed by the candidate network device 1 and the candidate network device 2 respectively.

[0212] like Fig. 9B As shown, the switching process may include:

[0213] 901: The source network device sends measurement configuration information to the terminal.

[0214] Correspondingly, the terminal receives the measurement configuration information from the source network device.

[0215] Optionally, the measurement configuration information may be carried in an RRC reconfiguration message. The measurement configuration information is used by the terminal to perform neighboring cell measurement, which is not limited here.

[0216] The neighboring cells mentioned in this application are neighboring cells of the terminal, including one or more of the same-frequency cell, different-frequency cell, and service cell. The same-frequency cell means that the SSB used for measurement has the same center frequency (central frequency) and subcarrier spacing (subcarrier spacing, SCS) as the cell-defining SSB of the service cell. The different-frequency cell means that the SSB used for measurement has at least one different center frequency and SCS from the cell-defining SSB of the service cell. The service cell refers to the cell that provides service to the terminal. The service cell may be a cell managed by the source network device, a cell covered by the source network device, a cell under the jurisdiction of the source network device, or a service cell belonging to the source network device.

[0217] Among them, step 901 may be an optional step.

[0218] 902: The terminal sends a measurement report to the source network device.

[0219] The measurement report includes the measurement result of the neighboring area measurement performed by the terminal according to the measurement configuration information.

[0220] Correspondingly, the source network device receives the measurement report from the terminal.

[0221] The measurement result involved in the present application may be the signal quality of the neighboring cell of the terminal, etc., which is not limited here.

[0222] Among them, step 902 may be an optional step.

[0223] 903: The source network device and the candidate network device 1 prepare for CHO switching.

[0224] For example, the source network device sends a handover request message to the candidate network device 1, and the handover request message is used to request the candidate network device 1 to prepare for the CHO handover; the source network device receives a handover request confirmation message from the candidate network device 1, and the handover request confirmation message may include information of the candidate cell 1. The handover request confirmation message may be understood as carrying the information of the candidate cell 1 configured by the candidate network device 1 for the terminal, and the information of the candidate cell 1 may be carried in the form of an RRC message of the candidate network device 1.

[0225] 904: The source network device and the candidate network device 2 perform CHO switching preparation.

[0226] For example, the source network device sends a handover request message to the candidate network device 2, and the handover request message is used to request the candidate network device 2 to prepare for the CHO handover; the source network device receives a handover request confirmation message from the candidate network device 2, and the handover request confirmation message may include, for example, information of the candidate cell 2. The handover request confirmation message may be understood as carrying the information of the candidate cell 2 configured by the candidate network device 2 for the terminal, and the information of the candidate cell 2 may be carried in the form of an RRC message of the candidate network device 2.

[0227] 905: The source network device sends CHO configuration information to the terminal.

[0228] The CHO configuration information includes CHO triggering condition information corresponding to the candidate cell 1 and the candidate cell 2 respectively.

[0229] Correspondingly, the terminal receives the CHO configuration information from the source network device.

[0230] The CHO configuration information may be carried in an RRC message generated by the source network device, such as an RRC reconfiguration message. The CHO configuration information may also include information about candidate cell 1 and information about candidate cell 2. Optionally, the CHO trigger condition information of candidate cell 1 and the CHO trigger condition information of candidate cell 2 are information generated by the source network device for the terminal.

[0231] When the CHO trigger condition information of the candidate cell 1 is the CHO trigger condition information based on time information, the source network device may also send the CHO trigger condition information to the candidate network device 1. When the CHO trigger condition information of the candidate cell 2 is the CHO trigger condition information based on time information, the source network device may also send the CHO trigger condition information to the candidate network device 2.

[0232] 906: The terminal determines a target cell.

[0233] Specifically, the terminal can determine whether the CHO triggering condition information of candidate cell 1 and candidate cell 2 is satisfied according to the CHO configuration information, and use the cell satisfying the CHO triggering condition information among candidate cell 1 and candidate cell 2 as the target cell (eg, candidate cell 1 is the target cell).

[0234] That is, in this step, the terminal measures each candidate cell to determine whether the CHO triggering condition of each candidate cell is met.

[0235] 907: The terminal accesses the target cell.

[0236] For example, the terminal initiates random access to a network device of a target cell (referred to as target network device) on random access resources, and the specific random access process is not limited herein.

[0237] 908: The terminal sends an RRC reconfiguration completion message to the target network device.

[0238] For example, the target network device is candidate network device 1, and the terminal can send an RRC reconfiguration completion message to candidate network device 1.

[0239] Correspondingly, candidate network device 1 receives the RRC reconfiguration completion message from the terminal.

[0240] The RRC reconfiguration complete message is used to indicate that the terminal has successfully accessed the candidate network device 1. Optionally, the RRC reconfiguration complete message may also include an identifier of a target cell.

[0241] It can be understood that after the terminal determines that the candidate cell 1 is the target cell, the candidate network device 1 can also be referred to as the target network device.

[0242] It should be noted that Fig. 9B This is only an example of the CHO process. The CHO process may have other variations, which are not limited in this application. Fig. 9B Each step in the process may be optional and the execution order of each step may be changed.

[0243] Therefore, in the NTN scenario, the network device configures multiple candidate cells for the terminal. If the terminal measures all the configured candidate cells, there will be measurement redundancy or invalid measurement, resulting in terminal energy waste. Based on this, the present application proposes a communication method, which optimizes the start-up measurement time of multiple candidate cells on the terminal side, thereby avoiding or reducing the terminal's measurement redundancy on the candidate cells and solving the problem of terminal energy waste.

[0244] The technical solution provided in this application can be executed by a terminal and a network device, or by a module and / or device (for example, a chip or an integrated circuit, etc.) with corresponding functions installed in a terminal or a network device, and this application is not limited thereto. Figure 10-12 The embodiments are described with terminals and network devices as the execution subjects. The network devices described in the following embodiments may be access network devices such as base stations.

[0245] The present application embodiment provides a communication method, which can be applied to NTN communication scenarios, such as the satellite communication scenarios working in the transparent transmission mode or the regeneration mode. Fig.10 As shown, the method may include the following steps.

[0246] 1001: The terminal sends a measurement report to the network device.

[0247] 1002: The network device determines at least one candidate cell.

[0248] Exemplarily, the network device may determine at least one candidate cell according to the received measurement report.

[0249] Among them, steps 1001 and 1002 are optional.

[0250] 1003: The network device sends first indication information to the terminal.

[0251] The first indication information is used to indicate the conditions for the terminal to perform measurements on at least one candidate cell. That is to say, when the network device configures multiple candidate cells for the terminal, the terminal does not need to measure all candidate cells, but can conditionally start measurements on some candidate cells. Specifically, the network device sends a first indication information to the terminal to indicate the judgment conditions for starting measurement for each candidate cell, so that the terminal can determine whether to start measurement for the candidate cell according to the conditions for performing measurements on the candidate cell included in the first indication information. Optionally, the measurement in this step may be a measurement of the signal quality of the candidate cell, or it may be a measurement of other measurement quantities related to the candidate cell, such as a measurement of the distance between the terminal and a reference point of the candidate cell, which is not limited in the present application.

[0252] In one implementation, the network device sends an RRC reconfiguration message to the terminal, and sends the configuration information of the candidate cell to the terminal. The first indication information can be carried in the RRC reconfiguration message, or carried in other messages, or can also be sent separately, and this application does not limit this. For example, for LTM switching, when the network device sends the configuration information of the candidate cell to the terminal, the network device sends the first indication information to the terminal. That is, the first indication information is carried in step 802 in the LTM process.

[0253] Below, the embodiments of the present application propose the following several conditions for determining the initiation of measurement on the candidate cell, including determining according to the initiation measurement time, determining according to the distance, or determining according to the angle, and several different indication methods corresponding to the first indication information respectively.

[0254] (1) Start measurement time

[0255] In an implementation manner, the first indication information may be used to indicate time information for starting measurement of one or more candidate cells among the at least one candidate cell.

[0256] It can be understood that the network device can indicate the time information of starting measurement of each candidate cell through the first indication information.

[0257] As can be seen from the above content, in the NTN scenario, with the high-speed movement of the satellite, the coverage area of ​​the ground, that is, the service cell, moves periodically. So for a certain terminal, the service cell of the terminal can change regularly with the movement of the satellite. For example, it can access several candidate cells in a certain order, such as Fig. 9A Therefore, the network device can determine the time when the terminal starts measuring the candidate cell according to the time when the signals of these candidate cells cover the terminal, thereby obtaining the first indication information. The time when the satellite signal covers a terminal can be understood as the time when the satellite can provide services for the terminal, and accordingly, the start time when the satellite signal covers the terminal can be called the service start time, or the coverage start time.

[0258] In one embodiment, the time information for starting the measurement may specifically be Universal Time Coordinated (UTC). For example, the first indication information may include UTC information for starting the measurement of one or more candidate cells. The UE starts the measurement of the corresponding cell only when the measurement start time arrives. Exemplarily, each candidate cell has a corresponding measurement start time. In another embodiment, the measurement start time corresponds to a cell list. In this case, the same measurement start time corresponds to multiple cells. Assuming that T1 corresponds to cell #1 and cell #2, and T2 corresponds to cell #3, the measurement of cells #1 and #2 can be started at time T1, and the measurement of cell #3 can be started at time T2. For example, satellite #1 and satellite #2 are two satellites in different orbits, and their coverage start time for the terminal device is the same, or the difference in coverage start time is less than a preset threshold, then the measurement of the cells corresponding to satellite #1 and satellite #2 can be started at the same time.

[0259] Alternatively, the time information for starting measurement of the candidate cell may also be indicated by the coverage start time of the candidate cell, such as the first indication information may include the coverage start time of one or more candidate cells. Thus, the terminal may independently decide the time to start measurement of the cell according to the coverage start time of the candidate cell.

[0260] It can be understood that in the above two ways of indicating the time information for starting measurement, the time when the terminal starts measuring each candidate cell is not earlier than the coverage start time of the candidate cell. In other words, the moment when the terminal starts measuring each candidate cell should be later than the coverage start time of the candidate cell for the terminal, or the coverage start time of the candidate cell for the terminal can be used as the moment when the measurement of the candidate cell is started.

[0261] For example, the UE accesses cell 1 at time T1, and then switches to cell 2, cell 3, and cell 4 in sequence. When the base station configures candidate cells for the UE, the configuration information of candidate cells 2 to 4 can be sent to the UE; at the same time, the base station can indicate the measurement start time of cell 2, cell 3, and cell 4 to the UE through the first indication information, such as T2, T3, and T4 respectively. Correspondingly, the UE can start measuring cell 2 at time T2, start measuring cell 3 at time T3, and start measuring cell 4 at time T4 according to the first indication information.

[0262] For another example, the base station can indicate to the UE the coverage start time of cell 2, cell 3, and cell 4, such as T2', T3', and T4', respectively, through the first indication information. Then, the UE can independently decide the time to start measurement of cell 2, cell 3, or cell 4 according to the coverage start time of cell 2, cell 3, and cell 4, for example, decide to start measuring cell 2 at time T2, start measuring cell 3 at time T3, and start measuring cell 4 at time T4, where T2≥T2', T3≥T3', and T4≥T4'.

[0263] Optionally, the first indication information may further include time information for stopping measurement of one or more candidate cells in the at least one candidate cell. The network device may indicate the time information for stopping measurement of each candidate cell through the first indication information.

[0264] In one implementation, the time information for stopping measurement may specifically be UTC information. For example, the first indication information may include UTC information for stopping measurement of one or more candidate cells. The terminal stops measuring the corresponding cell when the measurement stop time arrives. Alternatively, the time information for stopping measurement of the candidate cell may also be indicated by the coverage stop time of the candidate cell. The coverage stop time of the candidate cell refers to the time when the candidate cell stops covering the terminal or stops providing services for the terminal.

[0265] (2) Start measurement based on distance or angle

[0266] Since the satellite's operating position determines the coverage of the satellite signal, and thus determines the candidate cells of the terminal in the NTN scenario, parameters such as the distance between the terminal and the satellite, or the distance between the terminal and the satellite-related reference point, or the angle between the line connecting the terminal and the satellite and the horizontal or vertical direction, or the angle between the line connecting the terminal and the satellite-related reference point and the horizontal or vertical direction can all be used as conditions for the terminal to start measuring the candidate cells corresponding to the satellite.

[0267] Based on this, in an embodiment of the present application, by setting a threshold value for the distance or angle for starting measurement of a candidate cell, when performing cell switching, the distance or angle value related to the terminal and the satellite corresponding to the candidate cell is calculated and compared with the set distance threshold or angle threshold to determine whether to start measurement of the candidate cell.

[0268] In one implementation, the network device and the terminal may agree, or the protocol may specify, that the distance or angle between the terminal and the satellite is used as a condition for starting measurement of the candidate cell. Later in the switching process, the network device may indicate to the terminal through the first indication information the relevant parameters for calculating the distance or angle between the terminal and the satellite, so that the terminal can determine whether to start measurement of the candidate cell. Optionally, the network device may also agree with the terminal, or the protocol may specify the threshold of the distance or angle parameter, or the network device may also indicate to the terminal the threshold value of the distance or angle parameter for starting measurement. The specific indication method can refer to the description below.

[0269] Alternatively, in one embodiment, the first indication information may be used to instruct the terminal to determine to start measurement of the one or more candidate cells according to the distance or angle between the reference points corresponding to the one or more candidate cells in the at least one candidate cell. That is, the network device may instruct the terminal to use the distance or angle between the reference points corresponding to the candidate cells as a determination condition for starting measurement.

[0270] The reference point may be a position on the ground within the signal coverage of the satellite, which may be called a sub-satellite point, which is the point on the ground closest to the satellite; or, it may be a position where the satellite is located, which may be called an on-satellite point. Since the mobile position of the satellite is a factor in determining the coverage cell, and thus determining the candidate cell for subsequent switching of the terminal, the distance or angle between the satellite and the terminal may be determined according to the reference point corresponding to the satellite, as a judgment condition for starting measurement of the candidate cell.

[0271] Among them, according to the angle between the terminal and the reference point, it can specifically refer to the angle between the line connecting the terminal and the reference point and the horizontal direction or the vertical direction, and this application does not limit this.

[0272] In one implementation, the network device may configure a corresponding distance threshold or angle threshold for the terminal, for example, the network device may pre-configure the distance threshold or angle threshold for the terminal, or configure the distance threshold or angle threshold through the first indication information. The distance threshold or angle threshold may be a threshold value, respectively; or may be a numerical interval, that is, a distance or angle value range determined by at least two values.

[0273] In one implementation, if the distance threshold can specifically be a first threshold, the network device can send the first threshold to the terminal, and the first threshold is used to indicate: when the distance between the terminal and the reference point corresponding to the candidate cell satisfies the distance range corresponding to the first threshold, the measurement of the candidate cell is started. For example, the first threshold is an interval L1 to L2, and when the terminal determines that the distance between the reference point corresponding to the candidate cell is within the interval L1 to L2, the measurement of the candidate cell is started. Exemplarily, the distance within the interval L1 to L2 may include L1 and L2, or may not include L1 and L2.

[0274] Alternatively, in another implementation, if the angle threshold may specifically be a second threshold, the network device may send a second threshold to the terminal, where the second threshold is used to indicate that when the angle between the terminal and the satellite satisfies an angle range corresponding to the second threshold, measurement of the candidate cell is started.

[0275] In an implementation manner, the first indication information may also include location information of a reference point corresponding to the candidate cell, such as the location coordinates of the reference point.

[0276] For example, the first indication information may carry the location coordinates of the reference point corresponding to cell 1. The terminal may determine the distance between the terminal and the reference point based on the location coordinates of the terminal and the location coordinates of the reference point, and then determine whether to start measurement for the candidate cell based on the comparison between the distance between the terminal and the reference point and the first threshold.

[0277] Alternatively, in another embodiment, the first indication information may further include the relative position of a reference point corresponding to the candidate cell. For example, if the reference point is a sub-satellite point, the first indication information may include a position offset of the reference point relative to the satellite. In this case, the first indication information may further include ephemeris information and a reference time of the ephemeris information. The ephemeris information refers to a table recording the precise position or trajectory of the satellite over time, and the reference time of the ephemeris information may be epochTime.

[0278] Optionally, when the network device instructs the terminal to determine whether to perform measurement on the candidate cell based on the distance between the reference points corresponding to one or more candidate cells in at least one candidate cell, the network device may indicate the location information of the reference point corresponding to the candidate cell to the terminal, wherein the reference point is the sub-satellite point of the satellite, and the location information of the reference point may be the position offset of the sub-satellite point relative to the satellite. Furthermore, the first indication information may also include ephemeris information and the reference time of the ephemeris information. Thus, the terminal can calculate the location information of the satellite at this time based on the ephemeris information and the reference time, and then obtain the distance between the terminal and the reference point based on the location information of the satellite and the position offset of the reference point relative to the satellite. In this implementation, the location information of the reference point can be configured to the terminal through an RRC reconfiguration message.

[0279] Exemplarily, the network device configures the conditions for starting distance-based measurement of each candidate cell for the terminal, including the distance threshold, the location information of the reference point, and the ephemeris information. After receiving the distance threshold, the location information of the reference point, and the ephemeris information, the terminal calculates the distance between the terminal and the reference point, and starts the measurement if the distance threshold is met.

[0280] Similarly, when the network device configures the angle-based measurement start condition for the terminal, the ephemeris information of each candidate cell and the reference time of the ephemeris information can be carried at the same time. Exemplarily, the UE calculates the position of the satellite of the candidate cell according to the ephemeris information and the reference time, and then calculates the angle between the line connecting the terminal and the satellite and the horizontal direction or the vertical direction, and starts the measurement when the angle meets the angle range corresponding to the configured second threshold.

[0281] In one embodiment, the network device may also configure a threshold for stopping measurement of one or more candidate cells in at least one candidate cell for the terminal based on distance or angle. The terminal calculates whether the distance or angle to the reference point meets the condition for stopping measurement. If it is determined that the distance threshold or angle threshold is met, the terminal stops measuring the candidate cell.

[0282] Optionally, the first indication information may also include a distance or angle threshold for stopping measurement of one or more candidate cells in the at least one candidate cell. It is understandable that the network device may also indicate the distance or angle threshold for stopping measurement of each candidate cell through the first indication information.

[0283] (3) Perform measurements in sequence, for example, perform measurements in the order of the target cells in the RRC reconfiguration message.

[0284] The measurement is started only on the candidate cells for the next cell handover.

[0285] In one implementation, the first indication information is used to instruct the terminal to start measurement only on one or more candidate cells in the next cell handover, wherein the next cell handover refers to the terminal switching from the current serving cell to the next target cell.

[0286] That is, the network device can instruct the terminal that, for the multiple configured candidate cells, the terminal can start measurement only for the candidate cells of the next cell switching according to the order of switching to the candidate cells, that is, the terminal only starts measurement for the next hop candidate cell. In this implementation, the order of the configuration information of the candidate cells received (or stored) by the terminal is the order in which the terminal switches to the candidate cells.

[0287] like Fig. 9A In the NTN scenario shown, the next-hop candidate cell of cell 1 is cell 2, the next-hop candidate cell of cell 2 is cell 3, and so on. At this time, the network device can indicate to the terminal, or the protocol defaults that the candidate cells are configured in the order of coverage of the candidate cells. In one embodiment, when the network device sends the configuration information of the candidate cells to the terminal, the network device also sends the order of switching between the candidate cells to the terminal. For example, the order is cell 1, cell 2, cell 3, and so on. In this way, the terminal device can know that the next-hop candidate cell of cell 1 is cell 2, the next-hop candidate cell of cell 2 is cell 3, and so on.

[0288] For example, assuming that the base station configures only one candidate cell for the UE in each hop, the base station configures three candidate cells, namely, cell 2, cell 3 and cell 4, for the UE, and starts measuring cell 3 when the UE switches to cell 2, and starts measuring cell 4 when the UE switches to cell 3. This avoids redundant measurement of the candidate cells by the terminal and saves power consumption.

[0289] In one possible implementation, the network device may configure multiple candidate cells for the terminal at each cell switch. For example, when the terminal accesses cell 1, the candidate cells for the first cell switch after accessing cell 1 include cell 2 and cell 3, and the candidate cells for the second cell switch after the switching process for cell 2 or cell 3 is completed include cell 4. In this case, when the network device configures candidate cells for the terminal, it can add an identifier to indicate the round of cell switching, such as identifying cell 2 and cell 3 as candidate cells belonging to the same hop, marked as 1; cell 4 belongs to the candidate cell of the next hop, marked as 2. At this time, when the terminal accesses cell 1, it can start measuring cell 2 and cell 3; after the terminal switches to cell 2 or cell 3, it starts measuring cell 4, thereby avoiding redundant measurement of candidate cells by the terminal and saving power consumption.

[0290] In one implementation, the first indication information is further used to instruct the terminal to stop measuring the serving cell. For example, when the terminal switches from cell 1 to cell 2, the terminal stops measuring cell 1.

[0291] In one embodiment, for the LTM switching scenario, Figure 8 The switching process shown is similar. After the aforementioned steps 1001-1002, the specific process may further include the aforementioned steps 802-808.

[0292] Optionally, the first indication information in the above step 1002 can be carried in the RRC reconfiguration message of the configuration information of the candidate cell (for example, for the LTM switching scenario, the first indication information can be sent in step 802), or can be sent separately.

[0293] It should be noted that the above-mentioned scheme for indicating the start of measurement conditions provided in the embodiment of the present application can be applied not only to the LTM switching process, but also to other switching processes, such as CHO, or continuous switching, or Dual Active Protocol Stack (DAPS) switching and other scenarios, and the present application does not limit this. Among them, continuous switching refers to a scenario in which the terminal performs multiple cell switching within a period of time, and is not limited to the continuous LTM switching exemplified in the embodiment of the present application.

[0294] The above technical solution indicates the start measurement condition of the candidate cell to the terminal through the network device, so that the terminal can start or stop measuring the candidate cell that may be switched according to the order of cell switching, thereby avoiding the problem of terminal energy waste caused by the terminal measuring all candidate cells. In addition, the above multiple indication methods can increase the flexibility of indicating the start of cell measurement.

[0295] The foregoing Figure 8 In the existing LTM switching process described, after the cell switching is completed, the terminal can save the configuration information of multiple candidate cells (including the target cell) configured previously, so that when the terminal switches to the candidate cell next time, the network device can directly issue a switching command without sending the configuration information of the candidate cell again. However, in the NTN scenario, after the terminal completes the cell switching and accesses the target cell, the target cell will be used as the new candidate cell of the terminal in the next operation cycle of the corresponding satellite. If the terminal continues to save the configuration information of the candidate cell and the network device reserves the resources of the candidate cell for the terminal, it will cause a long time of resource waste.

[0296] In order to solve the above problems, the present application also provides a communication method, which optimizes the LTM switching process so that after the switching is completed, the terminal no longer retains the configuration information of the candidate cell configured for the current switching. In addition, the network device also releases the resources of the candidate cell, thereby solving the problem of resource waste and improving resource utilization.

[0297] In one implementation, it may be predefined through a protocol that after the terminal handover is completed, the configuration information of the source cell and / or other candidate cells of the current handover is deleted. Optionally, it may be stipulated through a protocol that if the access network of the terminal is NTN and LTM handover is adopted, the configuration information of the source cell is not saved after the terminal handover is completed, and the configuration information of other candidate cells except the target cell in the current handover is deleted.

[0298] In another implementation, a displayed indication signaling may be sent to the terminal through the network device, so that after the terminal completes the cell switching, the configuration information of the target cell and the candidate cell of the current switching is no longer retained.

[0299] like Fig.11 As shown, the method may include the following steps.

[0300] 1101: The terminal sends a measurement report to the network device.

[0301] 1102: The network device determines at least one candidate cell.

[0302] Among them, steps 1101 and 1102 are optional, and the specific description can refer to steps 1001 and 1002.

[0303] 1103: The network device sends second indication information to the terminal.

[0304] The second indication information is used to instruct the terminal to delete the configuration information of the serving cell or the configuration information of the serving cell as a candidate cell after switching from the serving cell (also called the source cell) to the target cell. In other words, the network device can instruct the terminal not to save the configuration information of the serving cell or the configuration information of the serving cell as a candidate cell after the cell switching is completed. That is, after each switching, the serving cell before the switching is not used as a candidate cell for the subsequent switching.

[0305] Optionally, if the network device configures one or more candidate cells for the terminal each time a cell switch is performed, the second indication information is used to indicate that after the cell switch is completed, the terminal can delete the configuration information of other candidate cells except the target cell in the same hop switch, and delete the configuration information of the service cell before the switch or the configuration information of the service cell as a candidate cell.

[0306] For example, the terminal currently accesses cell 1, and the candidate cells for the next handover are cell 2 and cell 3. When the terminal device switches to cell 2, the configuration information of cell 1 and the configuration information of cell 3 are deleted. Alternatively, when the terminal device switches to cell 2, cell 1, cell 2 and cell 3 are no longer used as candidate cells.

[0307] In one embodiment, the second indication information can be carried in an RRC reconfiguration message including configuration information of the candidate cell sent by the network device to the terminal (for example, in step 1103a), or carried in other messages, or can also be sent separately, which is not limited in this application.

[0308] In one implementation, the network device may also indicate the effective duration or effective time of each candidate cell to the terminal through the second indication information. For example, the second indication information may also include a first duration, which is the effective duration of a candidate cell. When the first duration expires or times out, the terminal may delete the configuration information of the candidate cell. Further, the terminal may delete the configuration information of the target cell for the secondary cell switching and at least one candidate cell after the first duration expires or times out.

[0309] In one implementation, the second indication information can be used to indicate that if LTM switching is performed, the configuration information of the source cell of the current switching is deleted after the terminal switching is completed. Optionally, the configuration information of other candidate cells of the current switching is further deleted. Specifically, the second indication information is used to indicate that if the access network of the terminal is NTN and LTM switching is adopted, the configuration information of the source cell as the candidate cell is not saved after the terminal switching is completed, and the configuration information of other candidate cells of the current switching is deleted. Optionally, after the switching is completed, the source cell and the candidate cell of the current switching (including the target cell) are not used as candidate cells.

[0310] In one implementation, step 1103 is optional. That is, the network device does not need to send the second indication information to the terminal. For example, the protocol stipulates that in the NTN scenario, the terminal deletes part or all of the configuration information of the candidate cell by default after switching from the serving cell to the target cell.

[0311] In one embodiment, for the LTM switching scenario, Figure 8 The switching process shown is similar, and the specific process may also include the following steps.

[0312] 1103a: The network device sends an RRC reconfiguration message to the terminal.

[0313] For the description of step 1103a, refer to the description of step 803.

[0314] Optionally, the RRC reconfiguration message includes second indication information.

[0315] The present application does not limit the order of steps 1103 and 1103a.

[0316] 1104: The terminal sends an RRC reconfiguration completion message to the network device.

[0317] Optionally, the LTM switching process may further include an early synchronization phase, which may specifically include step 1105 .

[0318] 1105: The terminal achieves uplink or downlink synchronization with the target cell.

[0319] 1106: The terminal measures the configured target cell and reports the L1 measurement result.

[0320] 1107: The network device determines whether to execute LTM switching according to the L1 measurement result. If LTM switching is to be executed, an LTM switching command is sent to the terminal to trigger the execution of the switching.

[0321] The LTM switching command may be a MAC CE, and the MAC CE may carry an identifier of the target cell configuration. The terminal uses the corresponding target cell configuration according to the identifier.

[0322] Optionally, if the UE needs to perform a random access process when switching to the target cell, step 1108 may be further included. For example, if the aforementioned step 1105 is not performed, that is, the terminal does not obtain the TA to achieve uplink synchronization, step 1108 may also be included.

[0323] 1108: The terminal randomly accesses the target cell.

[0324] 1109: The terminal sends an indication message of completing the cell switching to the network device.

[0325] 1110: The terminal deletes the configuration information of the candidate cell for secondary cell switching and / or the configuration information of the source cell.

[0326] At this time, if the network device configures multiple candidate cells for each cell switching of the terminal, the configuration information of all candidate cells of the same hop can be deleted after the terminal switching is completed. If the source cell is also a candidate cell (for example, the source cell also belongs to the candidate cell configured for the terminal in step 1103a), the terminal deletes the configuration information of the source cell as a candidate cell.

[0327] If the target cell accessed by the terminal is not one of the multiple candidate cells configured by the network device, the terminal can also delete the configuration information of the target cell. For example, if the next hop candidate cells configured by the network device for the terminal are cell 2 and cell 3, and the terminal eventually switches to other cells, the terminal can delete the configuration information of cell 2 and cell 3.

[0328] In one implementation, the terminal executes step 1110 according to the second indication information, that is, when the terminal receives the second indication information, the terminal executes step 1110, and when the terminal does not receive the second indication information, the terminal does not need to execute step 1110.

[0329] In another implementation, the protocol stipulates that in the NTN scenario, the terminal performs step 1110 by default after switching from the serving cell to the target cell.

[0330] In one implementation, after the terminal deletes the configuration information of the cell, it may also indicate the identifier of the deleted cell to the network device. Correspondingly, for example, the network device receives the identifier information of at least one cell from the terminal, and may determine that the terminal device deletes the configuration information of the at least one cell, so that the network device side may also determine to release the resources of the at least one cell according to the identifier of the cell deleted by the terminal.

[0331] Optionally, the network device may release the resources of at least one candidate cell corresponding to the secondary cell switching of the terminal or / and the resources of the source cell as the candidate cell (i.e., the configuration information of the candidate cell) after step 1109, i.e., after the network device receives the indication message of completing the cell switching sent by the terminal.

[0332] Alternatively, in one embodiment, the terminal may send a request message for releasing candidate cell resources to the network device after step 1109, so that the network device may release the resources of at least one candidate cell corresponding to the secondary cell switching of the terminal after receiving the request message for releasing candidate cell resources from the terminal.

[0333] In one embodiment, if the network device accessed by the terminal includes a CU and a DU, when the terminal switches between multiple cells corresponding to the same CU, the network device releases the resources of the candidate cell and / or the resources of the source cell, specifically including: the DU may send a release request to the CU to request the release of the resources of the candidate cell; the CU determines to release the resources of the candidate cell based on the release request, and optionally sends a release response to the DU; the DU releases the resources of the candidate cell corresponding to the secondary cell switch of the terminal based on the release response. Alternatively, the DU may send an indication message to the CU to indicate the cell identifier accessed by the terminal; the CU determines to release the resources of the candidate cell based on the indication message, and sends a request to the DU or other DUs to release the resources of the source cell of the terminal or / and the resources of at least one candidate cell corresponding to the secondary cell switch; alternatively, the CU may learn the target cell accessed by the terminal, and after the switch is completed, the CU determines to release the resources of the candidate cell, and specifically, the CU sends a request to the DU or other DUs to release the resources of the source cell of the terminal or / and the resources of at least one candidate cell corresponding to the secondary cell switch.

[0334] Among them, the terminal can perform cell switching between multiple candidate cells corresponding to one DU; or, perform cell switching between multiple candidate cells corresponding to multiple DUs, wherein the multiple DUs correspond to the same CU. That is to say, the terminal switches between multiple cells corresponding to the same CU, and the CU can instruct the corresponding target DU to perform resource release. Alternatively, the DU can send an indication message to the CU to indicate the cell identifier accessed by the terminal; the CU determines to release the resources of the candidate cell based on the indication message, and sends a request to the DU or other DUs to release the resources of the terminal's source cell or / and the resources of at least one candidate cell corresponding to the secondary cell switching.

[0335] In another embodiment, if the source network device of the terminal, such as the source base station, includes a CU and a DU, and the target network device of the terminal, such as the target base station, includes a CU and a DU, when the terminal switches between multiple cells corresponding to different CUs, if the network device releases the resources of the candidate cell, it specifically includes: the CU corresponding to the source cell sends a release request to the CU corresponding to the target cell to request the release of the resources of the candidate cell; the CU corresponding to the target cell sends a release request to the DU corresponding to the target cell based on the release request to request the release of the resources of the candidate cell; the DU corresponding to the target cell releases the resources of the candidate cell corresponding to the secondary cell switching of the terminal based on the release request. Exemplarily, the CU corresponding to the source cell is the CU in the source network device, which can be referred to as the source CU; the CU corresponding to the target cell is the CU in the target network device, which can be referred to as the target CU.

[0336] Among them, the terminal switches from the source cell to the target cell, and the CU corresponding to the target cell is different from the CU corresponding to the source cell, that is, the terminal switches between cells of multiple different CUs. Then, the source CU sends a resource release request to the target CU, so that the target CU can instruct the corresponding target DU to perform resource release according to the resource release request.

[0337] In the above implementation mode, based on the characteristics of cell switching in the NTN communication scenario, the network device can instruct the terminal to delete the configuration information of the candidate cell after the cell switching is completed. Accordingly, the network device can release the resources of the corresponding candidate cell, thereby avoiding long-term invalid resource reservation and effectively improving resource utilization.

[0338] In another implementation, if the handover fails, or the terminal switches to a cell other than the candidate cell, the candidate cell releases the resources reserved for the terminal. Specifically, if the candidate cell does not receive a handover completion message (such as an RRC reconfiguration completion message) within the specified time, the candidate cell releases the resources reserved for the terminal. The specified time may be the time when the terminal is expected to access the target cell, which may be carried in the handover request message. Alternatively, the service end time (or coverage end time) of the candidate cell for the terminal expires or times out, and the candidate cell releases the resources reserved for the terminal. Exemplarily, the service end time of the candidate cell for the terminal may be t-service.

[0339] In addition, the present application also provides a communication method, which can effectively reduce the signaling overhead of configuring resources by improving the way in which network equipment configures resources for terminals. Specifically, the network equipment side divides the configuration information of a candidate cell into two parts, one part of which is the common configuration information of the candidate cell (also referred to as cell-level configuration information, cell specific configuration), that is, the same part of the configuration information of all UEs in the candidate cell. The other part of the configuration information is mainly the different part of the configuration information of each UE in the candidate cell (also referred to as UE-level configuration information, UE specific configuration). The other part of the configuration information may also include some information that is the same for each UE in the candidate cell.

[0340] The network side broadcasts the common configuration information of the candidate cell through a broadcast message, so that when sending the configuration information of the candidate cell to the UE, it is not necessary to send the common configuration information of the candidate cell to each UE through a dedicated RRC message of each UE (also called a UE-level RRC message, such as an RRC reconfiguration message), thereby saving the signaling overhead generated by configuring the candidate cell. Further, when the multiple candidate cells configured by the network side for the UE are not directly in a neighboring relationship, the current serving cell does not broadcast the common configuration information of all candidate cells. The current serving cell only broadcasts the common configuration information of the candidate cells belonging to its own neighboring area. In this way, the signaling overhead caused by the serving cell broadcasting the common configuration information of the candidate cell can be reduced. It can also be understood that if the network side determines the candidate cell information for the terminal and determines the candidate cells that may be switched multiple times, a cell can only include the common configuration information of the candidate cell corresponding to the next cell switch of the terminal in the broadcast message, thereby further saving the signaling overhead of the common configuration information of the candidate cell in the broadcast message. For example, the current serving cell of the UE is cell 1, and the candidate cells configured by the network side for the terminal include cells 2, 3, and 4. Among them, the possible handover sequence of UE is handover from cell 1 to cell 2, from cell 2 to cell 3, and from cell 3 to cell 4. Cells 3 and 4 are not direct neighboring cells of cell 1, that is, UE will not handover from cell 1 to cell 3 or 4. Cell 4 is not a direct neighboring cell of cell 2, that is, UE will not handover from cell 2 to cell 4. In this case, cell 1 only needs to broadcast the public configuration information of cell 2, and does not need to broadcast the public configuration information of cells 3 and 4; cell 2 only needs to broadcast the public configuration information of cell 3, and does not need to broadcast the public configuration information of cell 4, and cell 3 only needs to broadcast the public configuration information of cell 4.

[0341] In one embodiment, Fig.12 As shown, the method may specifically include the following steps.

[0342] 1201: The terminal sends a measurement report to the network device.

[0343] 1202: The network device determines at least one candidate cell corresponding to the terminal.

[0344] Among them, steps 1201 and 1202 are optional.

[0345] Exemplarily, the network device may determine at least one candidate cell corresponding to the terminal according to the measurement report or other relevant information.

[0346] The following describes the method of determining and issuing configuration information of multiple candidate cells.

[0347] As can be seen from the above, the switching scenarios include intra gNB-DU, inter gNB DU intra gNB CU and inter gNB CU.

[0348] 1. In the intra gNB-DU scenario, multiple candidate cells of the terminal belong to the same DU. The CU can determine multiple candidate cells for the terminal when the terminal accesses cell 1, such as cell 2 to cell N; or, the current serving cell only determines the candidate cell for the next cell handover of the terminal, and the candidate cell determines the candidate cell for subsequent handover.

[0349] Exemplarily, according to the operation rules of the satellite, the cell switching sequence of the terminal is cell 1→cell 2 (or cell 3)→cell 4. When the terminal accesses cell 1, the candidate cells for the first cell switching may be cell 2 and cell 3, and the candidate cell for the second cell switching may be cell 4. Then, the CU may determine that the candidate cells of the terminal are cells 2, 3, and 4 when the terminal accesses cell 1. When cell 1 configures candidate cells for the terminal through a dedicated RRC message, only part of the configuration information of each candidate cell (i.e., the first configuration information described below) is carried in the dedicated RRC message, and the public configuration information of each candidate cell (i.e., the second configuration information described below) is not carried. Cell 1 broadcasts the public configuration information of cells 2 and 3, but does not broadcast the public configuration information of cell 4. Thus, each cell only broadcasts the public configuration information of other candidate cells when switching from the cell to other candidate cells, thereby saving signaling overhead.

[0350] In one implementation, the network device includes a CU and a DU, and the candidate cell is determined by the CU. The CU can send a UE Context Modification Request or a UE Context Setup Request message to the DU, and send the identifiers of multiple candidate cells to the DU to request configuration of the candidate cells for the terminal, and the DU performs access control. Specifically, the DU will accept some or all of the candidate cell requests, and send a UE Context Modification Response or a UE Context Setup Response message to the CU, indicating the access control result of the DU, and then the DU sends the configuration information of the determined candidate cell to the CU. The CU then sends it to the terminal.

[0351] Optionally, when the CU sends an identifier for configuring a candidate cell to the DU, the CU sends an indication message #A to the DU, indicating that when the DU returns the configuration information of the candidate cell, it only needs to return part of the configuration information (i.e., the first configuration information described below). Alternatively, the indication message #A indicates that when the DU returns the configuration information of the candidate cell, it does not need to return the common configuration information of the candidate cell.

[0352] 2. In the inter gNB DU intra gNB CU scenario, multiple candidate cells of the terminal may belong to different DUs but the same CU. Similarly, the CU can determine multiple candidate cells for the terminal when the terminal accesses cell 1, such as cell 2 to cell N; or, the current serving cell only determines the candidate cell for the next cell handover of the terminal, and the candidate cell determines the candidate cell for subsequent handover. For details, please refer to the description in intra gNB-DU.

[0353] 3. In the inter gNB CU scenario, the candidate cell of the terminal may belong to other CUs. The inter gNB CU scenario may also be referred to as the inter gNB scenario. The interaction between the source CU and the target CU may be referred to as the interaction between the source network device (also referred to as the source base station) and the target network device (also referred to as the target base station). At this time, the source network device may request the configuration information of the candidate cell from the target network device. Exemplarily, the source network device may send a handover request message to the target network device, and the target network device may reply to the source network device with a handover confirmation message, which may carry the configuration information of the candidate cell.

[0354] Optionally, in one implementation, in step 1202, the source network device may determine multiple candidate cells for subsequent switching of the terminal when preparing for switching. The multiple candidate cells may correspond to different network devices. The multiple candidate cells include the candidate cells in the target network device 1 when switching from the source network device to the target network device 1, and also include the candidate cells in the target network device 2 when switching from the target network device 1 to the target network device 2. That is, the source network device determines multiple candidate cells for subsequent cross-network device switching for the terminal. The switching confirmation message sent by the target network device 1 to the source network device carries the configuration information of the candidate cells in the target network device 1, and also includes the configuration information of the candidate cells in the target network device 2. For example, the switching request message sent by the source network device to the target network device 1 carries the identifiers of the multiple candidate cells determined by the source network device (including the identifiers of the candidate cells corresponding to the terminal switching from the target network device 1 to other target network devices). The switching request message sent by the source network device to the target network device 1 carries the identifiers of the candidate cells in the target network device 1. Further, the switching request message also carries the identifiers of the candidate cells in the target network device 2. After the target network device 1 receives the identifier of the candidate cell in the target network device 2 sent by the source network device, the target network device 1 sends a handover request message to the target network device 2, and the handover request message carries the identifier of the candidate cell in the target network device 2. The handover confirmation message sent by the target network device 2 to the target network device 1 carries the configuration information of the candidate cell in the target network device 2. Then, the handover confirmation message sent by the target network device 1 to the source network device carries the configuration information of the candidate cell in the target network device 2 and the configuration information of the candidate cell in the target network device 1. After that, the source network device sends the configuration information of the candidate cells in the target network device 1 and the target network device 2 to the terminal device.

[0355] Optionally, in another implementation, in step 1202, the source network device only determines one or more candidate cells in the next target network device 1 of the terminal when preparing for handover. The target network device 1 then determines one or more candidate cells when handing over from the target network device 1 to other network devices. For example, the handover request message sent by the source network device to the target network device 1 carries the identifier of the candidate cell in the target network device 1 determined by the source network device. Optionally, the handover request message also carries indication information, indicating that the target network device 1 can prepare candidate cells in other target network devices for the terminal. Afterwards, the target network device 1 determines the candidate cell in the target network device 2 when the terminal switches from the target network device 1 to the target network device 2. The target network device 1 sends a handover request message to the target network device 2, and the handover request message carries the candidate cell in the target network device 2 determined by the target network device 1. Afterwards, the handover confirmation message sent by the target network device 2 to the target network device 1 carries the configuration information of the candidate cell in the target network device 2. Then, the handover confirmation message sent by the target network device 1 to the source network device carries the configuration information of the candidate cells in the target network device 2 and the configuration information of the candidate cells in the target network device 1. Then, the source network device sends the configuration information of the candidate cells in the target network device 1 and the target network device 2 to the terminal device.

[0356] Optionally, the above two implementations may also be independent of the following steps 1203 to 1205. For example, in LTM switching, steps 802 to 808 are subsequently adopted. For another example, in CHO switching, steps 905 to 908 are subsequently adopted.

[0357] Optionally, the handover request message sent by the source network device to the target network device carries indication information #A, indicating that the target network device only sends part of the configuration information (i.e., the first configuration information described below) when sending the configuration information of the candidate cell to the source network device. Alternatively, the indication information #A indicates that the target network device does not need to send the common configuration information of the candidate cell when sending the configuration information of the candidate cell to the source network device.

[0358] Optionally, the source network device refers to a network device to which the terminal initially accessed most recently.

[0359] 1203: The network device sends an RRC reconfiguration message to the terminal, including the first configuration information.

[0360] The first configuration information may include partial configuration information of at least one candidate cell. That is, for at least one candidate cell, the first configuration information is only partial configuration information of the candidate cell. The terminal cannot obtain all configuration information of the candidate cell based on the configuration of the current serving cell and the first configuration information. The first configuration information at least includes UE-level configuration information of the terminal in at least one candidate cell. For example, the first configuration information includes at least one of the C-RNTI identifier allocated by the candidate cell to the UE, the radio link control layer configuration parameters, the packet data convergence protocol layer configuration parameters, and the service data adaptation protocol layer configuration parameters in the configuration information of the candidate cell.

[0361] 1204: The network device broadcasts the second configuration information.

[0362] Among them, the second configuration information includes the common configuration information of some candidate cells in at least one candidate cell determined in the aforementioned step 1202, and the part of the candidate cells refers to the candidate cells corresponding to the next cell switching performed by the terminal. In addition, the second configuration information corresponding to different candidate cells may be different, that is, the second configuration information refers to the cell-level configuration information. For example, the second configuration information may include the serving cell common configuration information (serving cell configuration common) of the candidate cell. The serving cell common configuration information may include the candidate cell identifier, the downlink frequency information of the candidate cell, the initial downlink bandwidth part (Bandwidth Part, BWP) of the candidate cell, the uplink frequency information of the candidate cell, the initial uplink bandwidth part of the candidate cell, the SSB position information of the candidate cell (for example, the time domain position of the SSB in the half frame, the SSB period, etc.), the subcarrier spacing of the SSB of the candidate cell, the power of the SSB of the candidate cell, etc.

[0363] The network device broadcasting the second configuration information in step 1204 means that each service cell only broadcasts the second configuration information corresponding to its own neighboring cell.

[0364] It can be seen that in the embodiments of the present application, the network device can send the UE-level configuration information of each candidate cell to the terminal through a dedicated RRC message (such as an RRC reconfiguration message); and the cell-level configuration information of the candidate cell can be sent through a broadcast message. Furthermore, each cell can only broadcast the cell-level configuration information of the candidate cell of the terminal in the next cell switching or only broadcast the cell-level configuration information corresponding to its own neighboring cell. For example, for the service cell 1 currently accessed by the terminal, only the cell-level configuration information of cell 2 and cell 3 is broadcast; cell 2 or cell 3 only broadcasts the cell-level configuration information of the candidate cell in the next cell switching, such as the cell-level configuration information of cell 4.

[0365] It should be noted that the resource configuration solution provided in the embodiment of the present application can be applied not only to the LTM switching process, but also to other switching processes, such as CHO, DAPS switching, or continuous switching scenarios, and the present application does not limit this.

[0366] The present application does not limit the order of steps 1204 and 1201 to 1203 .

[0367] 1205: The terminal obtains the first configuration information and the second configuration information.

[0368] Correspondingly, the terminal receives the RRC reconfiguration message from the network device and obtains the first configuration information, that is, obtains the UE-level configuration information of at least one candidate cell.

[0369] The terminal receives a broadcast message from the network device and obtains second configuration information, such as obtaining cell-level configuration information of a candidate cell corresponding to the next cell handover performed by the terminal.

[0370] For example, the terminal reads the system message of the candidate cell for the next handover in the current serving cell. The system message includes the second configuration information. The terminal device can obtain all the configuration information required to access the candidate cell from the first configuration information and the second configuration information.

[0371] Optionally, in step 1205, the terminal may obtain the first configuration information and the second configuration information at different times, and this application does not limit the order.

[0372] Optionally, if the terminal successfully receives the first configuration information and the second configuration information in the aforementioned steps 1203 and 1204, it means that the terminal successfully obtains the cell-level configuration information and UE-level configuration information of the candidate target cell configured by the network device for it. The combination of the two can obtain the full configuration information of at least one candidate cell.

[0373] Optionally, the terminal accesses the target cell. The terminal receives second configuration information sent by the target cell from the target cell, and the terminal obtains full configuration information of a candidate cell for the next handover of the terminal according to the first configuration information and the second configuration information sent by the target cell.

[0374] Exemplarily, if the terminal currently accesses cell 1, it will then switch to cell 2 and cell 3 in sequence, and the terminal receives an RRC reconfiguration message from the network device of cell 1 to obtain the first configuration information, including the UE-level configuration information of cell 2 and cell 3. In addition, the terminal can obtain the cell-level configuration information of cell 2 from the broadcast information of the network device of cell 1, so that the terminal obtains the full configuration information of cell 2 based on the cell-level configuration information of cell 2 combined with the UE-level configuration information of cell 2. Subsequently, when the terminal receives a switching command to switch to cell 2 (for example, a switching command in LTM switching) or the terminal determines to switch from cell 1 to cell 2 (for example, in CHO switching, the terminal determines that the triggering condition of cell 2 is met), it switches to cell 2. After the terminal accesses cell 2, the terminal can obtain the cell-level configuration information of cell 3 from the broadcast information of the network device of cell 2, so that the terminal obtains the full configuration information of cell 3 based on the cell-level configuration information of cell 3 combined with the UE-level configuration information of cell 3.

[0375] In one implementation, after the terminal obtains the full configuration information of at least one candidate cell, it may send a confirmation message to the network device corresponding to the current serving cell to indicate that the terminal has received the full configuration information of the candidate cell, or has received the public configuration information of the candidate cell. Optionally, the terminal may also send indication information to the network device corresponding to the current serving cell, indicating which candidate cells' full configuration information has been received or which candidate cells' public configuration information has been received.

[0376] It should be noted that the above steps 1201-1205 are only used to illustrate the steps executed by the communication device, and the order of the steps is not limited.

[0377] In one embodiment, Fig.12 The method shown is used for LTM switching scenarios. Please refer to the above Figure 8 and Fig.11 The switching process shown, for example Fig.12 In the method shown, after step 1204, the aforementioned steps 1104-1110 may also be included, which will not be repeated here.

[0378] In another embodiment, Fig.12 The method shown is used in the CHO scenario. For the CHO scenario, the terminal can also obtain the configuration information of the candidate cell through 1203 to 1205. For example, the source base station sends the terminal-level configuration information through the RRC reconfiguration message, and then broadcasts the system message of the neighboring cell. Correspondingly, the terminal receives the RRC reconfiguration message and reads the system message. The execution order of the two is not limited. In this way, the full configuration information of the candidate cell can be obtained. For example Fig.12In the method shown, after step 1204, the aforementioned steps 906-908 may also be included, which will not be repeated here.

[0379] In addition, Fig.11 Similar to the embodiment, after the network device receives the indication message of completing the cell switching sent by the terminal, it can release the resources of at least one candidate cell corresponding to the secondary cell switching of the terminal. Alternatively, after sending the indication message of completing the cell switching to the network device, the terminal can send a request message for releasing the candidate cell resources to the network device, so that the network device can release the resources of at least one candidate cell corresponding to the secondary cell switching of the terminal after receiving the request message for releasing the candidate cell resources from the terminal. Specifically, the process of the network device releasing the candidate cell resources can refer to the content of the aforementioned embodiment, which will not be repeated here.

[0380] In the above implementation, by adopting the above configuration delivery method, the network device can deliver the cell-level configuration information and UE-level configuration information of the candidate cell to the terminal, thereby reducing signaling overhead. In addition, after the cell switching of the terminal is completed, the network device can release the resources of the candidate cell reserved for the terminal, thereby further improving the utilization of resources.

[0381] It should be noted that the several implementation modes provided above in this application can be used individually or in combination, such as referring to the specific execution steps of each implementation mode applied in the same process, which will not be described one by one in this application.

[0382] In addition, the present application also provides a communication device, such as Fig.13 As shown, the communication device 1300 may include a processing module 1301 and a transceiver module 1302 .

[0383] Specifically, the communication device 800 can implement the above Figures 10 to 12 The functions of the terminal in each possible implementation manner may be specifically described in detail in the aforementioned method examples, and will not be elaborated here.

[0384] In addition, the present application also provides a communication device, which may be a network device, such as Fig.13 As shown, the communication device 1300 may include a processing module 1301 and a transceiver module 1302. The communication device has the function of implementing the above Figures 10 to 12 The functions of the network devices in the various possible implementations described above can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions.

[0385] For example, Fig.10In the illustrated implementation, if the communication device 1300 is used to implement the function of the network device, the processing module 1301 may be used to determine at least one candidate cell. The transceiver module 1302 may be used to send first indication information to the terminal, wherein the first indication information is used to indicate the condition for the terminal to perform measurement on the at least one candidate cell.

[0386] For example, Fig.10 In the illustrated implementation, if the communication device 1300 is used to implement the function of a terminal, the transceiver module 1302 is used to receive first indication information from a network device, where the first indication information is used to indicate a condition for the terminal to perform measurement on at least one candidate cell.

[0387] The specific execution process and embodiments in the above-mentioned communication device can refer to the steps executed by the terminal or network device in the above-mentioned method embodiment, and the related description. The technical problems solved and the technical effects brought about can also refer to the contents described in the above-mentioned embodiments, and will not be repeated here one by one.

[0388] Understandable, combined Fig.14 As shown, each network element involved in the embodiment of the present application, such as a terminal or a network device, can adopt Fig.14 The structure shown may include Fig.14 Parts shown. Fig.14 A schematic diagram of the structure of a communication device 1400 provided in an embodiment of the present application. When the communication device 1400 has the function of the terminal described in the embodiment of the present application, the communication device 1400 may be a terminal or a chip or system on chip in the terminal. When the communication device 1400 has the function of the network device described in the embodiment of the present application, the communication device 1400 may be a network device or a chip or system on chip in the network device.

[0389] like Fig.14 As shown, the communication device 1400 may include a processor 1401, a communication line 1402, and a communication interface 1403. Further, the communication device 1400 may also include a memory 1404. The processor 1401, the memory 1404, and the communication interface 1403 may be connected via the communication line 1402.

[0390] The processor 1401 may be a central processing unit (CPU), a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microprocessor, a microcontroller, a programmable logic device, or any combination thereof. The processor 1401 may also be other devices with processing functions, such as circuits, devices, or software modules.

[0391] The communication line 1402 is used to transmit information between the components included in the communication device 1400.

[0392] The communication interface 1403 is used to communicate with other devices or other communication networks. The other communication networks may be Ethernet, Radio Access Network (RAN), Wireless Local Area Networks (WLAN), etc. The communication interface 1403 may be an interface circuit, a pin, a radio frequency module, a transceiver, or any device capable of achieving communication.

[0393] The memory 1404 is used to store instructions, where the instructions may be computer programs.

[0394] Among them, the memory 1404 can be a read-only memory (ROM) or other types of static storage devices that can store static information and / or instructions, or a random access memory (RAM) or other types of dynamic storage devices that can store information and / or instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc (CD-ROM) or other optical disc storage, optical disc storage, magnetic disk storage medium or other magnetic storage device, and the optical disc storage includes a compressed optical disc, a laser disc, an optical disc, a digital versatile disc, or a Blu-ray disc, etc.

[0395] It should be noted that the memory 1404 can exist independently of the processor 1401, or can be integrated with the processor 1401. The memory 1404 can be used to store instructions or program codes or some data, etc. The memory 1404 can be located in the communication device 1400, or can be located outside the communication device 1400, without limitation. The processor 1401 is used to execute the instructions stored in the memory 1404 to implement the method provided in the embodiment of the present application.

[0396] In one example, the processor 1401 may include one or more CPUs, such as Fig.14 CPU0 and CPU1 in.

[0397] As an optional implementation, the communication device 1400 includes multiple processors, for example, Fig.14 In addition to the processor 1401, a processor 1407 may also be included.

[0398] As an optional implementation, the communication device 1400 further includes an output device 1405 and an input device 1406. Exemplarily, the input device 1406 is a keyboard, a mouse, a microphone, a joystick, and the like, and the output device 1405 is a display screen, a speaker, and the like.

[0399] It should be noted that the communication device 1400 can be a wearable device, a desktop computer, a portable computer, a network server, a mobile phone, a tablet computer, a wireless terminal, an embedded device, a chip system or a Fig.14 In addition, Fig.14 The structure shown in the figure does not constitute a limitation on the communication device, except Fig.14 In addition to the components shown, the communication device may include more or fewer components than shown, or combine certain components, or arrange the components differently.

[0400] In the embodiment of the present application, the chip system may be composed of a chip, or may include a chip and other discrete devices.

[0401] Combination Fig.13 As shown, exemplary, Fig.13 The function / implementation process of the processing module 1301 in Fig.14 The processor 1401 in the embodiment calls the computer program instructions stored in the memory 1404 to implement. For example, Fig.13 The function / implementation process of the transceiver module 1302 can be Fig.14 The communication interface 1403 in.

[0402] When the communication device 1300 is an electronic device, the above-mentioned transceiver module 1302 may be a transceiver, which may include an antenna and a radio frequency circuit, etc., and the processing module 1301 may be a processor, such as a baseband chip, etc. When the device is a component having the functions of a terminal or a network device in the above-mentioned embodiment, the transceiver module 1302 may be a radio frequency unit, and the processing module 1301 may be a processor. When the device is a chip system, the transceiver module 1302 may be an input interface and / or output interface of the chip system, and the processing module 1301 may be a processor of the chip system, such as a central processing unit (CPU).

[0403] In some embodiments, Fig.14 The processor 1401 in the device 1400 can call the computer execution instructions stored in the memory 1404 so that the device 1400 can perform the operations of the terminal or network device in the above-mentioned method embodiments, thereby realizing the above-mentioned possible implementation methods of the present application.

[0404] In this embodiment, the communication device is presented in the form of dividing various functional modules in an integrated manner. The "module" here may refer to a specific circuit, a processor and memory that executes one or more software or firmware programs, an integrated logic circuit, and / or other devices that can provide the above functions. In a simple embodiment, those skilled in the art can imagine that the communication device can be used as described above. Fig.14 The form shown.

[0405] In an exemplary embodiment, a computer-readable storage medium including instructions or a computer program product is also provided, and the instructions can be executed by the processor 1401 of the communication device 1400 to complete the method of the above embodiment. Therefore, the technical effects that can be obtained can refer to the above method embodiment, and will not be repeated here.

[0406] The present application also provides a computer program product, which includes instructions. When the instructions are executed, the computer can respectively perform operations of a terminal device or a network device corresponding to the above method.

[0407] The embodiment of the present application also provides a system chip, which includes: a processing unit and a communication unit, the processing unit, for example, may be a processor, and the communication unit, for example, may be an input / output interface, a pin or a circuit, etc. The processing unit may execute computer instructions so that the communication device used by the chip performs the operations of the terminal device and the network device in the method provided in the embodiment of the present application.

[0408] Optionally, any one of the communication devices provided in the above-mentioned embodiments of the present application may include the system chip.

[0409] Optionally, the computer instructions are stored in a storage unit.

[0410] An embodiment of the present application also provides a communication system, which may include: any one of the terminals and network devices in the above-mentioned implementation modes.

[0411] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using a software program, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.

[0412] The protocol described in this application may refer to a communication protocol or specification, such as a 3rd Generation Partnership Project (3GPP) communication protocol.

[0413] It is understandable that in the embodiment of the present application, the terminal and / or the network device can perform some or all of the steps in the embodiment of the present application, and these steps or operations are only examples. In the embodiment of the present application, other operations or variations of various operations can also be performed. In addition, each step can be performed in a different order presented in the embodiment of the present application, and it is possible not to perform all the operations in the embodiment of the present application.

[0414] In this application, "at least one" means one or more, and "more" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of this application, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0415] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0416] It should be noted that, in this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0417] In the various embodiments of the present application, unless otherwise specified or provided for in any logical conflict, the terms and / or descriptions between the different embodiments are consistent and may be referenced to each other, and the technical features in the different embodiments may be combined to form new embodiments according to their inherent logical relationships.

Claims

1. A communication method, characterized in that: The method comprises: determining at least one candidate cell; First indication information is sent to the terminal, where the first indication information is used to indicate a condition for the terminal to perform measurement on the at least one candidate cell.

2. The method according to claim 1, characterized in that: The first indication information is used to indicate time information for starting measurement of one or more candidate cells among the at least one candidate cell.

3. The method according to claim 2, characterized in that The time for starting measurement on each candidate cell is no earlier than the coverage start time of the candidate cell.

4. The method according to claim 2 or 3, characterized in that: The first indication information includes Universal Time (UTC) information for starting measurement of the one or more candidate cells.

5. The method according to claim 2 or 3, characterized in that: The first indication information includes coverage start time of the one or more candidate cells.

6. The method according to claim 1, characterized in that The first indication information is used to instruct the terminal to determine to start measurement on the one or more candidate cells according to the distance or angle between the reference points corresponding to the one or more candidate cells in the at least one candidate cell.

7. The method according to claim 1 or 6, characterized in that: The method further comprises: sending a first threshold to the terminal, where the first threshold is used to indicate that when the distance between the terminal and a reference point corresponding to the candidate cell satisfies a distance range corresponding to the first threshold, measurement of the candidate cell is started; or, A second threshold is sent to the terminal, where the second threshold is used to indicate that when an angle between the terminal and a reference point corresponding to the candidate cell satisfies an angle range corresponding to the second threshold, measurement of the candidate cell is started.

8. The method according to claim 6 or 7, characterized in that: The first indication information includes location information of the reference point.

9. The method according to claim 8, characterized in that The first indication information also includes ephemeris information and a reference time of the ephemeris information.

10. The method according to claim 1, characterized in that The first indication information is used to instruct the terminal to start measurement only on one or more candidate cells in the next cell handover.

11. The method according to any one of claims 1 to 10, characterized in that: The method is applied to non-terrestrial network NTN communications.

12. A communication method, characterized in that: The method comprises: First indication information is received from a network device, where the first indication information is used to indicate a condition for a terminal to perform measurement on at least one candidate cell.

13. The method according to claim 12, characterized in that The first indication information is used to indicate time information for starting measurement of one or more candidate cells among the at least one candidate cell.

14. The method according to claim 13, characterized in that The time for starting measurement on each candidate cell is no earlier than the coverage start time of the candidate cell.

15. The method according to claim 13 or 14, characterized in that The first indication information includes Universal Time (UTC) information for starting measurement of the one or more candidate cells.

16. The method according to claim 13 or 14, characterized in that The first indication information includes coverage start time of the one or more candidate cells.

17. The method according to claim 12, characterized in that The first indication information is used to instruct the terminal to determine to start measurement on the one or more candidate cells according to the distance or angle between the reference points corresponding to the one or more candidate cells in the at least one candidate cell.

18. The method according to claim 12 or 17, characterized in that The method further comprises: sending a first threshold to the terminal, When the distance between the terminal and the reference point corresponding to the candidate cell satisfies the distance range corresponding to the first threshold, starting measurement of the candidate cell; or, Sending a signal including a second threshold to the terminal, When the angle between the terminal and the reference point corresponding to the candidate cell satisfies the angle range corresponding to the second threshold, measurement of the candidate cell is started.

19. The method according to claim 17 or 18, characterized in that The first indication information includes location information of the reference point.

20. The method according to claim 19, characterized in that The first indication information also includes ephemeris information and a reference time of the ephemeris information.

21. The method according to claim 1, characterized in that The first indication information is used to instruct the terminal to start measurement only on one or more candidate cells in the next cell handover.

22. The method according to any one of claims 12 to 21, characterized in that: The method is applied to non-terrestrial network NTN communications.

23. A communication device, characterized in that: The method comprises a unit or module for executing the method according to any one of claims 1 to 11, or comprises a unit or module for executing the method according to any one of claims 12 to 22.

24. A communication device, characterized in that: include: one or more processors and one or more memories; The one or more memories are coupled to the one or more processors, and the one or more memories are used to store computer program codes, wherein the computer program codes include computer instructions. When the one or more processors execute the computer instructions, the communication device executes the method according to any one of claims 1 to 22.

25. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, and when the computer-executable instructions are called by the computer, the computer is used to enable the computer to execute the method described in any one of claims 1 to 22.

26. A computer program product, characterized in that When the computer program product is run on a computer, the computer is caused to execute the method according to any one of claims 1 to 22.

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