Communication method and communication apparatus

Abstract

The embodiments of the present application relate to the technical field of communications. Disclosed are a communication method and a communication apparatus, which can support a terminal to perform handover from a terrestrial cell to a satellite cell, and reduce the energy consumption of the terminal. In the method, a first network element in a non-terrestrial network may provide auxiliary information, wherein the auxiliary information is used by a terminal to access the non-terrestrial network from a terrestrial network; the terminal may receive first indication information, wherein the first indication information comprises the auxiliary information; and the terminal may access a target non-terrestrial network cell in at least one non-terrestrial network on the basis of the auxiliary information, wherein the target non-terrestrial network cell comprises a cell within the coverage range of a satellite. The embodiments of the present application are used in the process of a terminal accessing a non-terrestrial network cell from a terrestrial cell.

Description

A communication method and a communication device

[0001] This application claims priority to Chinese Patent Application No. 202411193444.1, filed on August 27, 2024, entitled "A Communication Method and Communication Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technology, and in particular to a communication method and a communication device. Background Technology

[0003] Considering the coverage gaps in terrestrial networks (TN), 5G introduces non-terrestrial networks (NTN). For example, when the NTN is a satellite network, the terminal can access the network via satellite cells. Thus, the terminal may move between TN and NTN. Typically, satellite cells have a wider coverage area than terrestrial cells, and when a terminal moves within the coverage area of ​​a satellite cell, it may enter the coverage area of ​​a terrestrial cell.

[0004] When a terminal moves between terrestrial and satellite cells, it may need to perform cell handover or cell reselection, i.e., the terminal switches from a terrestrial cell to a satellite cell. In connected mode, although terrestrial cells can be configured with neighboring satellite cell information, configuring this information is very complex due to the high speed of satellite movement. Furthermore, satellite and terrestrial cells typically belong to different operators, and cross-operator configuration of neighboring cell information is usually not supported, making handover from terrestrial to satellite cells impossible. In idle mode, the terminal needs to point its antenna at a specific range in the air for a full-frequency search. If no satellite cell is found, the terminal needs to adjust the antenna direction and re-search, a process that is time-consuming and power-intensive. Summary of the Invention

[0005] This application provides a communication method and a communication device that enables a terminal to switch from a terrestrial cell to a satellite cell when the terminal moves from the coverage area of ​​a terrestrial cell to an area without terrestrial cell coverage.

[0006] Firstly, a communication method is provided. The subject executing the method can be a terminal, a component or device applied to the terminal (such as a processor, chip, or chip system), or a logic module or software that can implement all or part of the terminal's functions. The method includes: receiving first indication information, the first indication information including auxiliary information, the auxiliary information being used by a terminal to access a non-terrestrial network from a terrestrial network, the auxiliary information being provided by a first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access; accessing a target non-terrestrial network cell (NTN cell) in at least one non-terrestrial network according to the auxiliary information, the target non-terrestrial network cell including cells within satellite coverage; wherein, the auxiliary information is used to indicate information of at least one satellite covering the terminal's location, the information of any one of the at least one satellite includes at least one of the following: satellite identifier, satellite ephemeris information, time information, satellite coverage information, or information of at least one cell or beam of the satellite, wherein the information of the satellite cell or beam includes at least one of the following: satellite cell or beam identifier, satellite cell or beam frequency information, satellite cell or beam scanning period, satellite cell or beam scanning time slot, satellite cell or beam coverage information, or the effective time of the satellite cell or beam information.

[0007] In this context, the non-terrestrial network can be, for example, a public land mobile network (PLMN). The first network element corresponding to the non-terrestrial network can be understood as a topology service or topology server within the non-terrestrial network. In the case of a satellite network, the first network element is the topology service or topology server within the satellite network.

[0008] In this context, a non-terrestrial network cell can be understood as a cell within the coverage area of ​​a non-terrestrial network device. For example, when the non-terrestrial network device is a satellite, the non-terrestrial network cell is a cell within the satellite's coverage area. When the non-terrestrial network device is a high-altitude platform, the non-terrestrial network cell is a cell within the high-altitude platform's coverage area.

[0009] Therefore, this application, by introducing a first network element in the non-terrestrial network—namely, topology services in the non-terrestrial network—can provide terminals with auxiliary information for accessing the non-terrestrial network from the terrestrial network, including information on at least one satellite covering the terminal's location. Thus, the terminal can determine the target non-terrestrial network cell based on the auxiliary information, allowing it to switch or reselect to that cell. This application, even when neighbor cell information cannot be configured between the non-terrestrial and terrestrial networks, can support a terminal's switch from a terrestrial cell to a non-terrestrial network cell when leaving or about to leave the coverage of the terrestrial network while in a connected state, through the auxiliary information provided by the first network element.

[0010] Moreover, the terminal does not need to frequently perform frequency searches when it leaves or is about to leave the coverage of the terrestrial network in an idle state. The terminal can perform satellite cell searches based on the satellite cells or beams indicated by the received auxiliary information, which can save the terminal's energy consumption.

[0011] In one possible design, before receiving the first indication information, the method further includes: sending capability information, which indicates that the terminal has at least one of the following capabilities: the terminal supports access via a non-terrestrial network cell, the terminal supports switching from a terrestrial cell to a non-terrestrial network cell for access, or the terminal supports redirection from a terrestrial cell to a non-terrestrial network cell for access. This capability information can be sent by the terminal when registering with the terrestrial core network. Thus, for the terrestrial core network, if it determines that the terminal has the capability to access a non-terrestrial network cell, it determines the non-terrestrial network that the terminal is allowed to access and the corresponding first network element.

[0012] In one possible design, before receiving the first indication information, the method further includes: receiving second indication information, the second indication information including the identifier of the first network element; and sending third indication information, the third indication information being used to request the first network element to provide auxiliary information, the third indication information including the location information of the terminal. This design is equivalent to the terminal requesting auxiliary information from the first network element based on the received identifier of the first network element. The first network element can directly send auxiliary information to the terminal so that the terminal can determine a target non-terrestrial network cell for access when there is no terrestrial network coverage.

[0013] In one possible design, accessing a target non-terrestrial network cell in at least one non-terrestrial network based on auxiliary information includes: determining the cells or beams of at least one candidate satellite based on the auxiliary information, and performing downlink synchronization with the cells or beams of the candidate satellite; measuring the cells or beams of the candidate satellite to obtain measurement results; and determining the target non-terrestrial network cell from the cells or beams of the candidate satellite based on the measurement results. In this design, it can be understood that when the terminal is in an idle state, it searches for satellite cells or beams indicated by the auxiliary information to determine the target non-terrestrial network cell. Compared to the existing methods that require full-frequency searches in an idle state, resulting in time and power consumption, in this application, the terminal device searches for satellite cells or beams indicated by the auxiliary information, which reduces the energy consumption of the terminal searching for non-terrestrial network cells.

[0014] In one possible design, accessing at least one target non-terrestrial network cell includes: camping on the target non-terrestrial network cell; or receiving and / or sending signaling and / or data through the target non-terrestrial network cell; or sending fourth indication information, which includes the identifier of the target non-terrestrial network cell, and is used to instruct the serving network device on the terrestrial network to initiate a process of switching the terminal to the target non-terrestrial network cell. This design can accommodate various possible scenarios for the terminal to access the target non-terrestrial network cell after determining it. For example, the terminal camps on the target non-terrestrial network cell in an idle state, or the terminal enters a connected state from an idle state and performs signaling and / or data transmission and reception through the target non-terrestrial network cell in the connected state. Alternatively, if the terminal determines that there is no terrestrial network coverage while in the connected state, it can initiate a process of switching to the target non-terrestrial network cell.

[0015] In one possible design, accessing a target non-terrestrial network cell in at least one non-terrestrial network based on auxiliary information includes: determining at least one candidate non-terrestrial network cell from the cells or beams of satellites indicated by the auxiliary information based on the terminal's location; measuring the candidate non-terrestrial network cells to obtain measurement results; sending fifth indication information, which includes the measurement results, to the serving network equipment of the terrestrial network to determine the target non-terrestrial network cell and initiate a process of switching the terminal to the target non-terrestrial network cell. This design can be understood as follows: when the terminal is in a connected state, if the terminal determines that it is leaving or about to leave the coverage of the terrestrial network, it determines candidate non-terrestrial network cells based on auxiliary information, determines the target non-terrestrial network cell from the candidate non-terrestrial network cells, and switches to the target non-terrestrial network cell. Even if the terrestrial cell of the serving network equipment and the target non-terrestrial network cell have different operators, in this application, the terminal equipment can still switch to the target non-terrestrial network cell through auxiliary information.

[0016] In one possible design, before determining candidate non-terrestrial network cells, the method further includes: receiving sixth indication information, which indicates that the terminal has moved out of or is about to move out of the coverage area of ​​a terrestrial network, or that the sixth indication information indicates that the terminal should measure the non-terrestrial network. That is, the terminal can determine whether to switch to a target non-terrestrial network cell based on the sixth indication information, so that the terminal can promptly switch to a non-terrestrial network cell when there is no terrestrial network coverage.

[0017] In one possible design, before sending the fifth indication information, the method further includes: sending a seventh indication information, which is used to request measurement configuration information of candidate non-terrestrial network cells from the first network element; and receiving an eighth indication information, which includes the measurement configuration information of the candidate non-terrestrial network cells. In this design, the first network element can not only provide auxiliary information but also provide the terminal with the measurement configuration information of non-terrestrial network cells, so that the terminal can measure the non-terrestrial network cells according to the measurement configuration information and determine the target non-terrestrial network cell.

[0018] Secondly, a communication method is provided. The executing entity of this method can be a core network device of a terrestrial network, a component or device (e.g., a processor, chip, or chip system) applied to the core network device, or a logic module or software capable of implementing all or part of the functions of the core network device. The method includes: obtaining the identifier of a first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access; sending first indication information, the first indication information being used to indicate auxiliary information to the terminal; or sending second indication information, the second indication information including the identifier of the first network element, the identifier of the first network element being used by the terminal to obtain auxiliary information from the first network element; or sending ninth indication information, the ninth indication information including the identifier of at least one non-terrestrial network that the terminal is allowed to access and the identifier of the first network element, the identifier of the first network element being used by the terminal's terrestrial network serving network device to obtain auxiliary information from the first network element.

[0019] The auxiliary information is used by the terminal to access the non-terrestrial network from the terrestrial network, and the auxiliary information is used to indicate information of at least one satellite covering the location of the terminal. The information of at least one satellite includes at least one of the following: satellite identification, satellite ephemeris information, time information, satellite coverage information, and information of at least one cell or beam of the satellite. The information of the cell or beam of the satellite includes at least one of the following: cell or beam identification, cell or beam frequency information, cell or beam scanning period, cell or beam scanning time slot, cell or beam coverage information, or the validity period of the cell or beam information.

[0020] For example, the core network equipment of the terrestrial network in the second aspect may be an access and mobility management function (AMF) network element or other network elements in the terrestrial core network.

[0021] Therefore, for the terrestrial core network accessed by the terminal, the terminal can obtain auxiliary information for switching from the terrestrial network to a non-terrestrial network by indicating the auxiliary information provided by the first network element or the identifier of the first network element of the terrestrial network. Alternatively, the serving network device can obtain auxiliary information from the first network element and send it to the terminal by indicating the identifier of the first network element, or the serving network device can determine candidate satellite cells or beams based on the auxiliary information obtained from the first network element, so that the terminal can initiate cell measurement and feed back the measurement results to the serving network device to determine the target non-terrestrial network cell. In this way, this application addresses the situation where neighbor cell information cannot be configured between the non-terrestrial network and the terrestrial network. The auxiliary information provided by the first network element can support the terminal to switch from the terrestrial cell to the non-terrestrial network cell, and the terminal does not need to frequently perform frequency point searches, saving terminal power consumption.

[0022] In one possible design, when sending the second indication information, the method further includes: in addition to sending the second indication information, sending a tenth indication information. This tenth indication information is used to instruct the terminal's serving network equipment on the terrestrial network that the terminal is permitted to switch from the terrestrial network to a non-terrestrial network. The tenth indication information includes an identifier of at least one non-terrestrial network that the terminal is permitted to access. That is, when the terrestrial core network instructs the terminal to obtain the identifier of the first network element for auxiliary information, the terrestrial core network can instruct the source terrestrial base station to indicate the identifier of at least one satellite network that the terminal is permitted to access. Thus, when the terminal determines a target non-terrestrial network cell based on the auxiliary information, the source terrestrial base station can determine, based on the identifier of at least one satellite network, that the terminal is permitted to switch to the target non-terrestrial network cell, thereby ensuring the terminal's network service performance.

[0023] In one possible design, before obtaining the identifier of the first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access, the method further includes: receiving capability information indicating that the terminal has at least one of the following capabilities: the terminal indicates access via a non-terrestrial network cell, the terminal supports handover from a terrestrial cell to a non-terrestrial network cell, or the terminal supports redirection from a terrestrial cell to a non-terrestrial network cell. Thus, the terrestrial core network, upon determining the terminal's capabilities, can identify the satellite networks and corresponding first network elements that the terminal is allowed to access, so that the terminal can switch to a satellite cell or beam based on auxiliary information provided by the first network element.

[0024] In one possible design, at least one non-terrestrial network and at least one corresponding first network element are determined based on the terminal's location information, subscription information, and roaming agreements between the terrestrial network operators and the non-terrestrial network operators. That is, the terrestrial core network can determine information from auxiliary information, such as subscription information and roaming agreements, that can cover the terminal's location, so that the terminal can determine the satellite cell or beam for access when there is no terrestrial network coverage.

[0025] In one possible design, before sending the first indication information, the method further includes: sending third indication information, which requests the first network element to provide auxiliary information, and the third indication information includes the terminal's location information; and receiving the first indication information, which includes the auxiliary information. This design is equivalent to the terrestrial core network requesting auxiliary information from the first network element and then sending it to the terminal, enabling the terminal to switch to a non-terrestrial network cell based on the auxiliary information when there is no terrestrial network coverage.

[0026] In one possible design, the method further includes: when the terminal moves out of or is about to move out of the coverage area of ​​any one of the at least one satellites in the auxiliary information, or when the terminal moves out of or is about to move out of the coverage area of ​​the cell or beam of any one of the at least one satellites, or when the validity period of the cell or beam information of any one of the at least one satellites expires or is about to expire, sending first information, the first information being used to request a first network element to update the auxiliary information, the first information including the terminal's current location information; receiving second information, the second information indicating the updated auxiliary information; and sending third information, the third information being used to indicate the updated auxiliary information to the terminal. That is, if it is determined that the terminal's auxiliary information is geographically invalid, i.e., the terminal has moved out of or is about to move out of the coverage area of ​​any one of the satellites indicated by the auxiliary information, or the coverage area of ​​the cell or beam of any one satellite, the ground core network can request the first network element to update the auxiliary information. Alternatively, if the ground core network determines that the terminal's auxiliary information is temporally invalid based on the validity period of the cell or beam information of any one satellite in the auxiliary information, i.e., the validity period of the cell or beam information of any one satellite does not include the current time, the ground core network can request the first network element to update the auxiliary information. This ensures that the terminal's auxiliary information remains valid both geographically and temporally, allowing the terminal to obtain effective auxiliary information so that it can select and access non-terrestrial networks based on that information.

[0027] Thirdly, a communication method is provided. The subject executing this method can be an access network device or core network device in a non-terrestrial network, or a component or device (e.g., a processor, chip, or chip system) applied to the access network device or core network device, or a logic module or software capable of implementing all or part of the functions of the access network device or core network device. For example, if the non-terrestrial network is a satellite network, the access network device or core network device can be understood as the first network element in this application, i.e., the topology service in the satellite network. The method includes: receiving third indication information, the third indication information being used to request auxiliary information, the auxiliary information being used by the terminal to access a non-terrestrial network from a terrestrial network, the third indication information including the location information of the terminal; sending first indication information, the first indication information including auxiliary information; wherein, the auxiliary information is used to indicate information of at least one satellite covering the location of the terminal, the information of at least one satellite including at least one of the following: satellite identifier, satellite ephemeris information, time information, satellite coverage information, information of at least one cell or beam of the satellite, wherein, the information of the cell or beam of the satellite includes at least one of the following: cell or beam identifier, cell or beam frequency information, cell or beam scanning period, cell or beam scanning time slot, cell or beam coverage information, or the validity period of the cell or beam information.

[0028] Therefore, for the first network element in the non-terrestrial network, upon receiving the third instruction information requesting auxiliary information, it can provide auxiliary information for the terminal to switch from the terrestrial network to the non-terrestrial network. In this way, for situations where neighbor cell information cannot be configured between the non-terrestrial and terrestrial networks, this application can support the terminal to switch from a terrestrial cell to a non-terrestrial network cell through the auxiliary information provided by the first network element. Moreover, the terminal does not need to frequently perform frequency point searches, saving terminal energy consumption.

[0029] In one possible design, the auxiliary information is determined based on the terminal's location information, the satellite constellation information of the satellite network, the configuration information of each satellite in the satellite network, and the current time information. That is, the first network element can store information about multiple satellite networks and the satellites within those networks. Based on the terminal's location information, the first network element can determine the satellite network that can cover the terminal's location and the satellite information itself—the auxiliary information. This allows the terminal or the source ground base station to determine candidate satellite cells based on the auxiliary information provided by the first network element, thereby identifying the target non-terrestrial network cell for handover.

[0030] In one possible design, the method further includes sending second information indicating updated auxiliary information. In this design, the updated auxiliary information could be sent to the terminal by the first network element based on changes in the satellite cell or beam in the previously determined auxiliary information, or the first network element could determine the need to update the auxiliary information based on changes in the terminal's location. Both approaches enable the terminal or the source ground base station to obtain effective auxiliary information, allowing the terminal to select and access non-terrestrial network cells based on the updated auxiliary information, thus improving the success rate of the terminal accessing non-terrestrial network cells.

[0031] In one possible design, before sending the second information, the method further includes: receiving first information, which indicates that the terminal has moved out of or is about to move out of the coverage area of ​​any one of the at least one satellites, or when the terminal has moved out of or is about to move out of the coverage area of ​​the cell or beam of any one of the at least one satellites, or when the validity period of the cell or beam information of any one of the at least one satellites has expired or is about to expire, requesting an update of auxiliary information, wherein the first information includes the terminal's current location information. Thus, when the auxiliary information is updated, a target non-terrestrial network cell can be selected for the terminal based on the updated valid auxiliary information, thereby improving the success rate of the terminal accessing the non-terrestrial network cell.

[0032] Fourthly, a communication method is provided. The executing entity of this method can be an access network device of a terrestrial network, a component or device (e.g., a processor, chip, or chip system) applied to the access network device, or a logic module or software capable of implementing all or part of the functions of the access network device. The access network device can be understood, for example, as a service network device for terminal services or a source terrestrial base station. The method includes: receiving tenth indication information, which indicates permission for a terminal to switch from a terrestrial network to a non-terrestrial network, the tenth indication information including an identifier of at least one non-terrestrial network to which the terminal is permitted access; receiving fourth or fifth indication information, the fourth indication information including an identifier of a target non-terrestrial network cell in at least one non-terrestrial network, the fifth indication information including measurement results of at least one candidate non-terrestrial network cell in at least one non-terrestrial network, the measurement results used to determine the target non-terrestrial network cell; and initiating a process to switch the terminal to the target non-terrestrial network cell based on the fourth or fifth indication information.

[0033] Therefore, in this application, the serving network equipment of the terminal on the terrestrial network can, based on determining the identifier of at least one non-terrestrial network that the terminal is allowed to access, assist the terminal in initiating a handover process from a terrestrial cell to a target non-terrestrial network cell when determining the target non-terrestrial network cell or the measurement results of the non-terrestrial network cell. In this way, this application addresses the situation where neighbor cell information cannot be configured between non-terrestrial and terrestrial networks, supporting the terminal's handover from a terrestrial cell to a non-terrestrial network cell through the serving network equipment of the terrestrial network. Furthermore, the terminal does not need to frequently perform frequency point searches, saving terminal energy consumption.

[0034] In one possible design, the tenth indication information further includes the identifier of at least one first network element corresponding to a non-terrestrial network; before receiving the fourth or fifth indication information, the method further includes: sending third indication information, which is used to request the first network element to provide auxiliary information, the auxiliary information being used by the terminal to access the non-terrestrial network from the terrestrial network and to indicate information of at least one satellite covering the terminal's location, the third indication information including the terminal's location information; receiving first indication information, the first indication information including auxiliary information; determining candidate non-terrestrial network cells in at least one non-terrestrial network based on the auxiliary information; and sending fourth information, which is used to instruct the terminal to measure the candidate non-terrestrial network cells, the fourth information including auxiliary information of the candidate non-terrestrial network cells.

[0035] In other words, in this design, the terminal's source ground base station can obtain auxiliary information from the first network element of the satellite network, determine candidate non-terrestrial network cells based on the auxiliary information, and instruct the terminal to measure the candidate non-terrestrial network cells. This eliminates the need for the terminal to obtain auxiliary information and determine candidate non-terrestrial network cells, thus saving terminal energy.

[0036] In one possible design, before receiving the fourth or fifth indication information, the system further includes sending a sixth indication information. This sixth indication information indicates that the terminal has moved out of or is about to move out of the coverage area of ​​the terrestrial network. Alternatively, it indicates that the terminal is about to leave or has already left the terrestrial cell, and the terminal needs to identify candidate non-terrestrial network cells and measure them in order to switch to the target non-terrestrial network cell.

[0037] In one possible design, before sending the fourth or sixth instruction information, the process further includes determining whether the terminal has moved out of or is about to move out of the terrestrial network coverage area. That is, the source terrestrial base station can determine in real time whether the terminal has moved out of the terrestrial network coverage area based on the terminal's location, instructing the terminal to measure non-terrestrial networks and promptly switch to the target non-terrestrial network cell.

[0038] In one possible design, the fourth information also includes measurement configuration information of candidate non-terrestrial network cells. Before sending the fourth information, the method further includes: sending a seventh indication message, which requests the measurement configuration information of candidate non-terrestrial network cells from the first network element; and receiving an eighth indication message, which includes the measurement configuration information of candidate non-terrestrial network cells obtained by the first network element. In this way, the source terrestrial base station can not only determine candidate non-terrestrial network cells in the non-terrestrial network based on auxiliary information, but also obtain the measurement configuration information of the candidate non-terrestrial network cells from the first network element, and send the identifiers and measurement configuration information of the candidate non-terrestrial network cells to the terminal so that the terminal can measure the candidate non-terrestrial network cells. This avoids the energy consumption incurred by the terminal in determining candidate non-terrestrial network cells and obtaining measurement configuration information.

[0039] Fifthly, a communication device is provided, which may be a terminal, a component or device applied to a terminal (such as a processor, chip, or chip system), or a logic module or software capable of realizing all or part of the terminal functions. The method includes: a receiving unit, configured to receive first indication information, the first indication information including auxiliary information, the auxiliary information being used by a terminal to access a non-terrestrial network from a terrestrial network, the auxiliary information being provided by a first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access; and a processing unit, configured to access a target non-terrestrial network cell in at least one non-terrestrial network according to the auxiliary information, the target non-terrestrial network cell being a satellite cell; wherein the auxiliary information is used to indicate information of at least one satellite covering the terminal's location, the information of any one of the at least one satellite includes at least one of the following: satellite identifier, satellite ephemeris information, time information, satellite coverage information, or information of at least one cell or beam of the satellite, wherein the information of the satellite cell or beam includes at least one of the following: satellite cell or beam identifier, satellite cell or beam frequency information, satellite cell or beam scanning period, satellite cell or beam scanning time slot, satellite cell or beam coverage information, or the effective time of the satellite cell or beam information.

[0040] In one possible design, a transmitting unit is also included for transmitting capability information, which indicates that the terminal has at least one of the following capabilities: the terminal supports access via a non-terrestrial network cell, the terminal supports switching from a terrestrial cell to a non-terrestrial network cell for access, or the terminal supports redirection from a terrestrial cell to a non-terrestrial network cell for access.

[0041] In one possible design, the receiving unit is further configured to receive second indication information, the second indication information including the identifier of the first network element; the sending unit is further configured to send third indication information, the third indication information being used to request the first network element to provide auxiliary information, the third indication information including the location information of the terminal.

[0042] In one possible design, the processing unit is used to perform downlink synchronization with cells or beams of at least one satellite based on auxiliary information; to measure the cells or beams of the partial satellites and obtain measurement results; and to determine the target non-terrestrial network cell from the cells or beams of the partial satellites based on the measurement results.

[0043] In one possible design, the processing unit is configured to reside in the target non-terrestrial network cell; or, the processing unit is configured to receive and / or send signaling and / or data through the target non-terrestrial network cell; or, the sending unit is configured to send fourth indication information, the fourth indication information including the identifier of the target non-terrestrial network cell, the fourth indication information being used to instruct the terminal's serving network equipment on the terrestrial network to initiate a process of handing the terminal over to the target non-terrestrial network cell.

[0044] In one possible design, a processing unit is configured to determine at least one candidate non-terrestrial network cell from the cells or beams of satellites indicated by auxiliary information based on the location of the terminal; to measure the candidate non-terrestrial network cell and obtain measurement results; and a transmitting unit is configured to transmit fifth indication information, the fifth indication information including the measurement results, the measurement results being used by the terrestrial network service network equipment to determine the target non-terrestrial network cell and to initiate a process of the terminal switching to the target non-terrestrial network cell.

[0045] In one possible design, the receiving unit is also used to receive a sixth indication information, which indicates that the terminal has moved out of or is about to move out of the coverage area of ​​the terrestrial network, or the sixth indication information indicates that the terminal is used to measure a non-terrestrial network.

[0046] In one possible design, the transmitting unit is further configured to transmit a seventh indication information before transmitting the fifth indication information, the seventh indication information being used to request measurement configuration information of the candidate non-terrestrial network cell from the first network element; the receiving unit is further configured to receive an eighth indication information, the eighth indication information including the measurement configuration information of the candidate non-terrestrial network cell.

[0047] Sixthly, a communication device is provided. This device can be a core network device of a terrestrial network, a component or apparatus (e.g., a processor, chip, or chip system) applied to the core network device, or a logic module or software capable of implementing all or part of the core network device's functions. The communication device includes: a processing unit configured to acquire an identifier of a first network element corresponding to at least one non-terrestrial network that a terminal is allowed to access; a sending unit configured to send first indication information, which indicates auxiliary information to the terminal; or, send second indication information, which includes the identifier of the first network element, which is used by the terminal to obtain auxiliary information from the first network element; or, a sending unit configured to send ninth indication information, which includes the identifier of at least one non-terrestrial network that the terminal is allowed to access and the identifier of the first network element, which is used by the terminal's terrestrial network service network equipment to obtain auxiliary information from the first network element.

[0048] The auxiliary information is used by the terminal to access the non-terrestrial network from the terrestrial network, and the auxiliary information is used to indicate information of at least one satellite covering the location of the terminal. The information of at least one satellite includes at least one of the following: satellite identification, satellite ephemeris information, time information, satellite coverage information, and information of at least one cell or beam of the satellite. The information of the cell or beam of the satellite includes at least one of the following: cell or beam identification, cell or beam frequency information, cell or beam scanning period, cell or beam scanning time slot, cell or beam coverage information, or the validity period of the cell or beam information.

[0049] In one possible design, when the sending unit sends the second indication information, it also sends a tenth indication information in addition to sending the second indication information. The tenth indication information is used to instruct the terminal's service network equipment on the terrestrial network to allow the terminal to switch from the terrestrial network to a non-terrestrial network. The tenth indication information includes an identifier of at least one non-terrestrial network that the terminal is allowed to access.

[0050] In one possible design, a receiving unit is also included for receiving capability information indicating that the terminal has at least one of the following capabilities: the terminal indicates access via a non-terrestrial network cell, the terminal supports handover from a terrestrial cell to a non-terrestrial network cell for access, or the terminal supports redirection from a terrestrial cell to a non-terrestrial network cell for access.

[0051] In one possible design, at least one non-terrestrial network and at least one first network element corresponding to the non-terrestrial network are determined based on the terminal's location information, subscription information, and roaming agreements between the terrestrial network operator and the non-terrestrial network operator.

[0052] In one possible design, before sending the first indication information, the sending unit is further configured to: send a third indication information, the third indication information being used to request the first network element to provide auxiliary information, the third indication information including the terminal's location information; and the receiving unit is further configured to receive the first indication information, the first indication information including auxiliary information.

[0053] In one possible design, the transmitting unit is further configured to: transmit first information when the terminal moves out of or is about to move out of the coverage area of ​​any one of the at least one satellites, or when the terminal moves out of or is about to move out of the coverage area of ​​the cell or beam of any one of the at least one satellites, or when the validity period of the cell or beam information of any one of the at least one satellites expires or is about to expire, the first information being used to request the first network element to update auxiliary information, the first information including the terminal's current location information; the receiving unit is further configured to receive second information, the second information indicating the updated auxiliary information; the transmitting unit is further configured to: transmit third information, the third information being used to indicate the updated auxiliary information to the terminal.

[0054] In a seventh aspect, a communication device is provided. This communication device can be an access network device or core network device for a non-terrestrial network, or it can be a component or apparatus (e.g., a processor, chip, or chip system) applied to the access network device or core network device, or it can be a logic module or software capable of implementing all or part of the functions of the access network device or core network device. For example, if the non-terrestrial network is a satellite network, the access network device or core network device can be understood as the first network element in this application, i.e., the topology service in the satellite network. The communication device includes: a receiving unit for receiving third indication information, the third indication information being used to request auxiliary information, the auxiliary information being used by a terminal to access a non-terrestrial network from a terrestrial network, the third indication information including the location information of the terminal; and a sending unit for sending first indication information, the first indication information including auxiliary information; wherein the auxiliary information is used to indicate information of at least one satellite covering the location of the terminal, the information of at least one satellite including at least one of the following: satellite identifier, satellite ephemeris information, time information, satellite coverage information, and information of at least one cell or beam of the satellite, wherein the information of the cell or beam of the satellite includes at least one of the following: cell or beam identifier, cell or beam frequency information, cell or beam scanning period, cell or beam scanning time slot, cell or beam coverage information, or the validity period of the cell or beam information.

[0055] In one possible design, the auxiliary information is determined based on the terminal's location information, the satellite constellation information of the satellite network, the configuration information of each satellite in the satellite network, and the current time information.

[0056] In one possible design, the sending unit is also used to send second information, which is used to indicate the updated auxiliary information.

[0057] In one possible design, before sending the second information, the receiving unit is also configured to receive first information, which is used to indicate that the terminal has moved out of or is about to move out of the coverage area of ​​any one of the at least one satellites, or when the terminal has moved out of or is about to move out of the coverage area of ​​the cell or beam of any one of the at least one satellites, or when the validity period of the cell or beam information of any one of the at least one satellites has expired or is about to expire, requesting an update of auxiliary information. The first information includes the terminal's current location information.

[0058] Eighthly, a communication device is provided. This device can be an access network device for a terrestrial network, a component or apparatus (e.g., a processor, chip, or chip system) applied to the access network device, or a logic module or software capable of implementing all or part of the functions of the access network device. The access network device can be understood, for example, as a service network device for terminal services or a source terrestrial base station. The communication device includes: a receiving unit for receiving tenth indication information, which indicates permission for a terminal to switch from a terrestrial network to a non-terrestrial network, and includes an identifier of at least one non-terrestrial network to which the terminal is permitted access; the receiving unit is further configured to receive fourth or fifth indication information, where the fourth indication information includes an identifier of a target satellite cell within the satellite coverage area of ​​at least one non-terrestrial network, and the fifth indication information includes measurement results of at least one candidate satellite cell in the non-terrestrial network, the measurement results used to determine the target satellite cell; and a processing unit for initiating a process of switching the terminal to the target satellite cell based on the fourth or fifth indication information.

[0059] In one possible design, the tenth indication information further includes the identifier of at least one first network element corresponding to a non-terrestrial network; it also includes a sending unit, configured to send a third indication information before receiving the fourth or fifth indication information, the third indication information being used to request the first network element to provide auxiliary information, the auxiliary information being used by the terminal to access the non-terrestrial network from the terrestrial network and to indicate information about at least one satellite covering the terminal's location, the third indication information including the terminal's location information; a receiving unit, further configured to receive the first indication information, the first indication information including the auxiliary information; a processing unit, further configured to determine at least one candidate satellite cell in the non-terrestrial network based on the auxiliary information; and a sending unit, further configured to send fourth information, the fourth information being used to instruct the terminal to measure the candidate satellite cell, the fourth information including the auxiliary information of the candidate satellite cell.

[0060] In one possible design, before receiving the fourth or fifth indication information, the sending unit is also used to send a sixth indication information, which is used to indicate that the terminal has moved out of or is about to move out of the coverage area of ​​the terrestrial network, or the sixth indication information is used to indicate that the terminal performs measurements on a non-terrestrial network.

[0061] In one possible design, before sending the fourth message or the sixth instruction message, the processing unit is also used to determine the coverage area of ​​the terrestrial network from which the terminal has moved out or is about to move out.

[0062] In one possible design, the fourth information also includes measurement configuration information of candidate non-terrestrial network cells; before sending the fourth information, the sending unit is also used to send a seventh indication information, which is used to request the measurement configuration information of candidate non-terrestrial network cells from the first network element; the receiving unit is also used to receive an eighth indication information, which includes the measurement configuration information of candidate non-terrestrial network cells obtained by the first network element.

[0063] A ninth aspect provides a communication device, including at least one processor connected to a memory, the at least one processor being configured to read and execute a program stored in the memory, such that the device performs the method as described in the first aspect or any of the first aspects above, or performs the method as described in the second aspect or any of the second aspects above, or performs the method as described in the third aspect or any of the third aspects above, or performs the method as described in the fourth aspect or any of the fourth aspects above.

[0064] A tenth aspect provides a computer-readable storage medium storing computer instructions that, when executed on a communication device, cause the communication device to perform the method described in the first aspect or any one thereof, or to perform the method described in the second aspect or any one thereof, or to perform the method described in the third aspect or any one thereof, or to perform the method described in the fourth aspect or any one thereof.

[0065] Eleventhly, a computer program product is provided, which, when run on a computer or processor, causes the computer or processor to execute the communication method in any of the above aspects and any possible implementations.

[0066] In a twelfth aspect, a communication system is provided, which may include a terminal, a first network element, a terrestrial network service network device, and a terrestrial network core network device, as described in any possible implementation of any of the above aspects. The communication system can execute the communication methods described in any of the above aspects and any possible implementations.

[0067] In a thirteenth aspect, a communication device is provided that can be used as a module performing the method as described in the first aspect or any of the first aspects above, or as a module performing the method as described in the second aspect or any of the second aspects above, or as a module performing the method as described in the third aspect or any of the third aspects above, or as a module performing the method as described in the fourth aspect or any of the fourth aspects above.

[0068] It is understood that any of the terminals, first network elements, service network equipment of the terrestrial network, core network equipment of the terrestrial network, computer-readable storage media or computer program products provided above can be applied to the corresponding methods provided above. Therefore, the beneficial effects that can be achieved can be referred to the beneficial effects in the corresponding methods, and will not be repeated here.

[0069] These or other aspects of this application will become more readily apparent in the following description. Attached Figure Description

[0070] Figure 1 is a schematic diagram of a network architecture that integrates terrestrial and non-terrestrial networks to provide services to terminals, as well as a schematic diagram of the satellite orbital plane and the Earth's equatorial plane, provided by an embodiment of this application.

[0071] Figure 2 is a coverage diagram of a satellite cell and a ground cell provided in an embodiment of this application;

[0072] Figure 3 is a flowchart illustrating a communication method provided in an embodiment of this application;

[0073] Figure 4 is a flowchart illustrating a communication method provided in an embodiment of this application;

[0074] Figure 5 is a flowchart illustrating a communication method provided in an embodiment of this application;

[0075] Figure 6 is a flowchart illustrating a communication method provided in an embodiment of this application;

[0076] Figure 7 is a flowchart illustrating a communication method provided in an embodiment of this application;

[0077] Figure 8 is a schematic diagram of satellite coverage information provided in an embodiment of this application;

[0078] Figure 9 is a schematic diagram of the distribution of a satellite beam on the ground according to an embodiment of this application;

[0079] Figure 10 is a flowchart illustrating a communication method provided in an embodiment of this application;

[0080] Figure 11 is a flowchart illustrating a communication method provided in an embodiment of this application;

[0081] Figure 12 is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0082] Figure 13 is a schematic diagram of the structure of a communication device provided in an embodiment of this application. Detailed Implementation

[0083] This application can be applied to a network architecture that integrates terrestrial networks (TN) and non-terrestrial networks (NTN). Non-terrestrial networks are an important supplement to terrestrial cellular communication technology and represent one of the technological directions for direct satellite connection to terminals. By integrating satellite communication networks with terrestrial networks, ubiquitous coverage can be provided regardless of terrain, connecting multiple dimensions of space, air, land, and sea to form an integrated ubiquitous access network, enabling on-demand access across all scenarios.

[0084] There are two common architectures for non-terrestrial network technologies: transparent mode, also known as transparent forwarding or transparent payload; and regenerative mode, also known as regenerative payload or base station onboarding. Transparent forwarding essentially treats the satellite merely as a signal relay link. The 5G base station, as part of the terrestrial network, is deployed behind the gateway station in the NTN. The satellite does not process the signals transmitted by the base station; it simply acts as a bridge between the terminal and the gateway station. Base station onboarding, on the other hand, deploys the functionality of the 5G base station on the satellite. The inter-satellite links are similar to the Xn interface between terrestrial base stations, and the feeder link between the satellite and the gateway station can be understood as part of the backhaul network between the base station and the core network. In short, the satellite possesses all or part of the functions of a base station, capable of processing data before transmitting it to the terminal.

[0085] Terrestrial networks can be wireless communication systems such as 5G and future possible communication technologies, including but not limited to narrowband internet of things (NB-IoT), global system for mobile communications (GSM), enhanced data rate for GSM evolution (EDGE), wideband code division multiple access (WCDMA), code division multiple access 2000 (CDMA2000), time division-synchronization code division multiple access (TD-SCDMA), long term evolution (LTE), and the three major application scenarios of 5G mobile communication systems: enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and enhanced machine-type communication (eMTC), as well as future possible mobile communication systems.

[0086] Figure 1(a) shows a schematic diagram of a network architecture 100 that integrates terrestrial and non-terrestrial networks to provide services to terminals. In this network architecture 100, the terrestrial network may include a terrestrial radio access network (RAN) 1001 and a terrestrial core network 1002, while the non-terrestrial network may include a satellite radio access network 1003 and a satellite core network 1004. The network architecture 100 also includes a terminal 1005.

[0087] The terrestrial radio access network 1001 may include at least one RAN node, and may also include other RAN nodes, such as wireless relay equipment and / or wireless backhaul equipment. Terminals connect to RAN nodes wirelessly. Terminals and RAN nodes can be interconnected via wired or wireless means. RAN nodes connect to the terrestrial core network via wireless or wired means. The core network equipment in the terrestrial core network and the RAN nodes in the RAN may be independent physical devices, or they may be the same physical device integrating the logical functions of the core network equipment and the logical functions of the RAN node.

[0088] A RAN node, also known as a radio access network device, RAN entity, or access node, is used to help terminals access a communication system wirelessly. In one application scenario, an RAN node can be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next-generation NodeB (gNB) in a 5G mobile communication system, or a base station in a future mobile communication system. An RAN node can be a macro base station, a micro base station, an indoor station, a relay node, or a donor node. In this application, the terrestrial radio access network 1001 is used as an example of a terrestrial base station for illustration.

[0089] The terrestrial core network 1002 is connected to terrestrial base stations. The terrestrial core network 1002 may also include access and mobility management function (AMF) network elements, session management function (SMF) network elements, unified data management (UDM) network elements, network exposure function (NEF) network elements, and authentication server function (AUSF) network elements. In future networks, the functions of the terrestrial core network may be recombined; this application applies to the core network of future networks after the recombination of terrestrial core network functions.

[0090] In this network architecture 100, the satellite core network 1004 and the terrestrial core network 1002 can be co-located, meaning that a single core network device can simultaneously support both terrestrial and satellite access. The satellite core network 1004 and the terrestrial core network 1002 can also be partially co-located and partially separated; this application does not impose any limitations on this. The satellite core network 1004 may include topology services, which can communicate with the open-source network elements within the satellite core network 1004.

[0091] In this application, the terrestrial core network 1002 can receive the capabilities of the terminal 1005 and determine whether the terminal 1005 can access the network via a non-terrestrial network and whether it supports switching to a non-terrestrial network based on the terminal 1005's capabilities, subscription information, and roaming agreement. If it is determined that switching to a non-terrestrial network is supported, the terrestrial core network 1002 can send an indication to the terrestrial base station that the terminal 1005 supports switching to a non-terrestrial network. The terrestrial core network 1002 can also select a non-terrestrial network for the terminal 1005 to access, select the corresponding topology service for the non-terrestrial network, and send the address information of the topology service to the terminal 1005 or obtain auxiliary information from the topology service and send it to the terminal 1005. The auxiliary information is used by the terminal 1005 to switch from the terrestrial network to the non-terrestrial network. For example, the auxiliary information can be understood as the information of the satellite cell in this application. When the source terrestrial base station triggers cell handover, the terrestrial core network 1002 can also obtain the auxiliary information and send it to the source terrestrial base station. For example, the functions of the terrestrial core network 1002 in this application can be performed by the AMF network element or by other network elements of the terrestrial core network 1002, and this application does not limit this.

[0092] When the ground base station determines that there are no available ground cells for terminal 1005, it triggers a handover to a non-terrestrial network and sends a handover notification to terminal 1005. The ground base station can also receive a target satellite cell or measurement report selected by terminal 1005 (selecting a target satellite cell based on the measurement report). The ground base station can also trigger a cell handover or reselection process via the core network. The ground base station can also request auxiliary information from the topology service and send it to terminal 1005. Based on the auxiliary information, the ground base station can also determine candidate satellite cells or satellite beams, obtain measurement configuration information, and send an indication of the candidate satellite cell or satellite beam and the measurement configuration information to terminal 1005.

[0093] The satellite wireless access network 1003 includes a satellite base station. In this application, the satellite base station can be connected to the satellite core network 1004. The satellite base station can be deployed on a satellite. This application does not limit the deployment location of the satellite base station. That is, the satellite base station can be deployed on the ground, i.e., in a transparent mode, with only the radio frequency module of the base station deployed on the satellite. The satellite base station can also adopt a regenerative mode, possessing some of the functions of a base station. The satellite base station can communicate with the satellite core network 1004 through the gateway station 1006.

[0094] In this application, the satellite base station can send measurement configuration information of candidate satellite cells or beams to the topology service. The satellite base station can also perform the process of a terminal handover or reselection from a terrestrial cell to a satellite cell.

[0095] Terminal 1005 is a device with wireless transceiver capabilities, capable of sending signals to or receiving signals from a base station. The base station can be a terrestrial base station or a non-terrestrial base station in transparent or regenerative mode, such as a satellite base station. The terminal can also be referred to as a terminal device, user equipment (UE), mobile station, mobile terminal, etc. Terminals can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, smart cities, etc. Terminals can be mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, airplanes, ships, robots, robotic arms, smart home devices, etc. The embodiments of this application do not limit the specific technology or device form used in the terminal.

[0096] In this application, terminal 1005 can send capability information to ground core network 1002 and receive auxiliary information from the network or directly obtain auxiliary information from topology services. Terminal 1005 can search for and select target satellite cells based on auxiliary information, or measure candidate satellite cells. In idle state, terminal 1005 can access the network through the selected target satellite cell; in connected state, terminal 1005 can send indications or measurement reports of the target satellite cell to the ground base station.

[0097] As shown in Figure 1(a), this application can add a topology service to the non-terrestrial network of network architecture 100. The topology service can calculate the information of a satellite cell based on the topology information of any satellite in the constellation. The information of the satellite cell includes at least one of the following: satellite identifier, satellite ephemeris information, time information, satellite coverage information, information of at least one cell or beam of the satellite, measurement configuration information, priority information, or the identifier of the public land mobile network (PLMN) to which the satellite cell belongs. The satellite cell belongs to a non-terrestrial base station. The topology service can return information of satellite cells covering an area or location upon request, i.e., auxiliary information. When described with the Earth coordinate system as the reference coordinate system, the topology information of the satellite includes the following information: the satellite's orbital altitude (starting from the Earth's center), the satellite's orbital inclination (the angle between the orbital plane and the equatorial plane), the right ascending node of the satellite's orbit at a certain moment (the point where the satellite moves from south to north and intersects the equator; due to the Earth's rotation, the right ascending node of the orbit changes over time), and the phase information of the satellite in its orbit at that moment (starting from the right ascending node). Based on the satellite's topology information, the topology service can calculate the satellite's coordinates and velocity at any given moment, using the Earth's coordinate system as a reference. Figure 1(b) shows a schematic diagram of the satellite's orbital plane and the Earth's equatorial plane. In Figure 1(b), the orbital plane of satellite c is plane b1, the Earth's equatorial plane is plane b2, the ascending node is point a (ascending node) shown in Figure 1(b), Ω is the longitude of the ascending node, the orbital inclination is i (ascending node) shown in Figure 1(b), and the phase of satellite c in its orbit is ν+ω, where ν is the true anomaly and ω is the argument of periapsis. After determining the satellite's coordinates, the topology service also calculates the satellite's coverage area (coverage range) on the Earth's surface based on the satellite's configuration information, where the configuration information refers to the angle of satellite coverage, as explained in Figure 8. In addition, the satellite configuration information includes the number of satellite beams, the radius of beam coverage, the frequency configuration of the beams, the physical cell identifier, and the beam scanning pattern. The topology service can determine information about at least one cell or beam of the satellite based on the above configuration information, as illustrated in Figure 9. For example, the topology service sends auxiliary information to terminal 1005 upon request. For terminal 1005 in a connected state, the auxiliary information may also include information for measuring candidate satellite cells. In this application, the topology service can be a server or other network element, and this application does not limit its scope. This application does not limit the deployment location of the topology service; for example, the topology service can be deployed in the satellite radio access network 1003 or in the satellite core network 1004.

[0098] In the embodiments of this application, the functions of the base station can be executed by modules (such as chips) within the base station, or by a control subsystem that includes base station functions. This control subsystem, including base station functions, can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. The functions of the terminal can also be executed by modules (such as chips or modems) within the terminal, or by a device that includes terminal functions. The functions of the core network equipment can also be executed by modules (such as chips) within the core network equipment, or by a device that includes core network equipment functions. The functions of the topology service can also be executed by modules (such as chips) within the topology service, or by a device that includes topology service functions.

[0099] Considering the coverage gaps in terrestrial networks, 5G introduces non-terrestrial networks, such as satellite network access, allowing terminals to access the network via satellite. The introduction of satellite networks enables operators to provide network access to areas previously lacking terrestrial network coverage, filling these gaps. This allows terminals to move between terrestrial and non-terrestrial networks. Typically, the coverage area of ​​a non-terrestrial network cell is wider than that of a terrestrial network cell. In other words, a satellite cell has a wider coverage area than a terrestrial cell. When a terminal moves within the coverage area of ​​a terrestrial cell, it may move out of that coverage area, but the area may still have coverage from a non-terrestrial network cell. Figure 2 illustrates the coverage of non-terrestrial network cells and terrestrial cells. In V2X communication, vehicle 204, during its movement, may pass through non-terrestrial network cell 201 or enter terrestrial cells 202 or 203. When vehicle 204 moves between terrestrial and non-terrestrial network cells, it may need to perform cell handover or cell reselection. Therefore, when vehicle 204 leaves or is about to leave the coverage area of ​​the terrestrial cell it has accessed, it can switch or reselect to a non-terrestrial network cell.

[0100] Understandably, when a terminal is in an idle state and moves between cells, it can perform cell reselection to access the network through a new cell. When searching for a target cell, if the terminal does not know the target cell's frequency information, it needs to try searching on various different frequencies supported by the terminal. Therefore, cell search is a time-consuming and power-intensive process. In terrestrial networks, ground base stations broadcast information about neighboring cells to help the terminal quickly search for neighboring cells. For example, ground base stations broadcast information such as the identifier and center frequency of neighboring cells. The terminal can then use this information to search for specific frequencies, thereby reducing cell search time and saving power.

[0101] However, taking satellite cells as an example of non-terrestrial network cells, the search for satellite cells, especially those in the Ku or Ka bands, requires the terminal to search not only in terms of frequency but also in terms of space. That is, the terminal needs to point its antenna at a specific area in the sky to search for frequencies. If the terminal fails to find a satellite cell, it needs to adjust the antenna direction and search again. This process is very time-consuming and power-intensive.

[0102] In terrestrial networks, when a terminal is in a connected state, for handover between base stations, the source base station needs to be aware of the configuration information of neighboring cells and instruct the terminal to measure the candidate cells based on their configuration information. The source base station then selects the target cell based on the measurement results. This requires terrestrial cells to configure neighboring cell information with adjacent satellite cells to support handover from terrestrial to satellite cells. However, due to the high dynamism of satellites and the barriers between operators—namely, the rapid movement of satellites and the quick changes in neighboring cells of terrestrial cells, configuring neighboring cells is very complex. It is difficult for satellite cells and terrestrial cells to configure neighboring cell information with each other, and when satellite cells and terrestrial cells belong to different operators, cross-operator configuration of neighboring cell information is usually not supported. Therefore, handover from terrestrial to satellite cells cannot be supported.

[0103] Therefore, this application proposes a communication method and apparatus that introduces topology services into a non-terrestrial network. These topology services can determine auxiliary information for at least one satellite cell or satellite beam based on terminal location information, satellite information, and time information. This auxiliary information can be used to assist the terminal in selecting a target non-terrestrial network cell (e.g., a satellite cell or satellite beam) and switching from a terrestrial cell to the target non-terrestrial network cell when moving from the coverage area of ​​a terrestrial cell to an area without terrestrial cell coverage. Simultaneously, this auxiliary information can also avoid the time-consuming and power-consuming problem caused by frequent cell searches during idle states.

[0104] Based on this, Figure 3 shows a flowchart of a communication method. In this method, the terminal can receive auxiliary information for accessing a non-terrestrial network from the topology service of the satellite core network, and then access the target non-terrestrial network cell based on the auxiliary information. The method includes the following steps.

[0105] 301. The terminal receives first indication information, which includes auxiliary information. The auxiliary information is used by the terminal to access a non-terrestrial network from a terrestrial network. The auxiliary information is provided by a first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access.

[0106] Among them, the non-terrestrial network can be understood as the satellite network, the core network of the non-terrestrial network can be understood as the satellite core network, and the access network of the non-terrestrial network can be understood as the satellite base station.

[0107] The first network element can be understood as a topology service or topology server in a non-terrestrial network, or a topology service or topology server in a satellite network. The first network element can determine auxiliary information for the terminal to access a non-terrestrial network from a terrestrial network based on the terminal's location information and relevant satellite network information.

[0108] In some embodiments, the terminal receiving the first indication information includes: the terminal receiving the first indication information through a terrestrial cell.

[0109] For the terminal, the first indication information received by the terminal may be auxiliary information requested by the ground core network from the first network element and sent to the terminal by the ground core network; or it may be the identifier of the first network element received by the terminal from the ground core network and requested by the terminal from the first network element; or it may be sent to the terminal by the terminal's service network equipment on the ground network, i.e., the source ground base station, after obtaining the first indication information from the first network element.

[0110] The at least one non-terrestrial network that a terminal is allowed to access can be one or more. For example, at least one non-terrestrial network can be at least one non-terrestrial PLMN. The first network element corresponding to at least one non-terrestrial network can be one or more. When the terrestrial core network determines that there are multiple non-terrestrial PLMNs that a terminal is allowed to access, the terrestrial core network can send the identifier of the first network element of each non-terrestrial PLMN to the terminal.

[0111] The identifier of the first network element may include, for example, the Internet Protocol (IP) address or the fully qualified domain name (FQDN) of the first network element.

[0112] In some embodiments, auxiliary information is used to indicate information about at least one satellite covering the location of the terminal. The information of any one of the at least one satellite includes at least one of the following: satellite identifier, satellite ephemeris information, time information, satellite coverage information, and information about at least one cell or beam of the satellite. The information about the satellite cell or beam includes at least one of the following: satellite cell or beam identifier, satellite cell or beam frequency information, satellite cell or beam scanning period, satellite cell or beam scanning time slot, satellite cell or beam coverage information, or the effective time of the satellite cell or beam information. The effective time indicates the time during which the satellite cell or beam serves the area indicated by the satellite cell or beam coverage information, such as start and end time, or start time and duration, etc. The effective time indicates the time slice in which the satellite cell or beam serves the area. The auxiliary information may include information about multiple satellites, which indicates the information of satellite cells or beams serving the same area within different time slices (e.g., multiple consecutive time slices). The same time slice may also include information from multiple satellites. For example, when the coverage area of ​​a cell or beam with multiple satellites in the same time slice includes the terminal location, the auxiliary information may include information from multiple satellites.

[0113] The satellite's ephemeris information may include its coordinates, speed, and direction of movement. The satellite's time information may be the time the satellite was at those coordinates. The satellite's coverage information may be an indication of its coverage area using a center position and radius.

[0114] 302. The terminal accesses at least one target non-terrestrial network cell in a non-terrestrial network based on auxiliary information. The target non-terrestrial network cell includes cells within the satellite coverage area.

[0115] Among them, the target non-terrestrial network cell can be a satellite cell or a cell covered by a satellite beam.

[0116] In some embodiments, when the terminal is in an idle state and there are no available ground cells (the terminal moves out of the coverage area of ​​a ground cell), the terminal may perform downlink synchronization with cells or beams of at least some satellites based on auxiliary information; measure the cells or beams of some satellites to obtain measurement results; and determine the target non-terrestrial network cell from the cells or beams of some satellites based on the measurement results.

[0117] After identifying a target non-terrestrial network cell, the terminal's access to at least one of the target non-terrestrial network cells may include: the terminal camping on the target non-terrestrial network cell, for example, the terminal monitoring or receiving broadcast messages or paging messages from the target non-terrestrial network cell in idle state; or, the terminal receiving and / or sending signaling and / or data through the target non-terrestrial network cell; and / or, the terminal may also initiate signaling procedures through the target non-terrestrial network, such as initiating a registration update or tracking area update, to switch the terminal's context from the terrestrial core network to the non-terrestrial core network, change the terminal's access method from terrestrial access to non-terrestrial access, and change the terminal's location from terrestrial network location information (such as the tracking area identifier of the terrestrial network) to non-terrestrial network location information (such as the tracking area identifier or geographical location information of the non-terrestrial network).

[0118] In some embodiments, when the terminal is in a connected state, for example, when the terminal determines that it has moved out of or is about to move out of the coverage area of ​​a terrestrial network, or when the terminal receives an indication from a terrestrial base station that the terminal is about to move out of the coverage area of ​​a terrestrial network, the terminal may determine at least one candidate non-terrestrial network cell from the cells or beams of satellites indicated by auxiliary information based on the terminal's location. The terminal measures the candidate non-terrestrial network cells and obtains measurement results. The terminal determines the target non-terrestrial network cell based on the measurement results and sends fourth indication information, which includes the identifier of the target non-terrestrial network cell. The fourth indication information is used to instruct the terrestrial network serving network equipment to perform a procedure to switch the terminal to the target non-terrestrial network cell.

[0119] In some embodiments, when the terminal is in a connected state, for example, when the terminal determines that it has moved out of or is about to move out of the coverage area of ​​a terrestrial network, or when the terminal receives an indication from a terrestrial base station that the terminal is about to move out of the coverage area of ​​a terrestrial network, the terminal may determine at least one candidate non-terrestrial network cell from the cells or beams of satellites indicated by auxiliary information based on the terminal's location. The terminal measures the candidate non-terrestrial network cells and obtains the measurement results. The terminal then sends fifth indication information, which includes the measurement results. The measurement results are used by the serving network equipment of the terrestrial network to determine the target non-terrestrial network cell and initiate a process for the terminal to switch to the target non-terrestrial network cell.

[0120] Therefore, this application, by introducing a first network element in the non-terrestrial network—namely, topology services in the non-terrestrial network—can provide terminals with auxiliary information for accessing the non-terrestrial network from the terrestrial network, including information on at least one satellite covering the terminal's location. Thus, the terminal can determine the target non-terrestrial network cell based on the auxiliary information, such as the satellite's cell or beam, so that the terminal can switch or reselect to the target non-terrestrial network cell. This application can support the terminal's switch from a terrestrial cell to a non-terrestrial network cell even when neighbor cell information cannot be configured between the non-terrestrial and terrestrial networks, through the auxiliary information provided by the first network element.

[0121] Moreover, when a terminal moves from the coverage area of ​​a terrestrial cell to the coverage area of ​​a cellless area while in idle state, it does not need to frequently perform frequency point searches, thus saving the terminal's energy consumption.

[0122] Accordingly, for the terrestrial core network, it can determine the non-terrestrial networks that the terminal is allowed to access and the first network element corresponding to the non-terrestrial network, so as to obtain auxiliary information from the first network element and send it to the terminal. Alternatively, the terrestrial core network can also send the identifier of the first network element to the terminal or the terminal's serving network device on the terrestrial network, so that the terminal or the serving network device can request auxiliary information from the first network element. Figure 4 shows a flowchart of a communication method provided in an embodiment of this application, which includes the following steps.

[0123] 401. The terrestrial core network obtains the identifier of the first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access.

[0124] In some embodiments, the terrestrial core network may acquire at least one non-terrestrial network that allows terminal access and at least one first network element corresponding to the non-terrestrial network.

[0125] In some embodiments, at least one non-terrestrial network that the terminal is allowed to access, and at least one first network element corresponding to the non-terrestrial network, are determined by the terrestrial core network based on the terminal's location information, subscription information, and roaming agreements between the terrestrial network operator and the non-terrestrial network operator.

[0126] For example, the terrestrial core network here may be an AMF network element or other network elements in the terrestrial core network, and this application does not limit it. The terrestrial core network can determine whether to allow the terminal to access a non-terrestrial network through the terminal's capability information and subscription information. For example, when the terminal's capability information indicates that it supports access through a non-terrestrial network and the terminal's subscription information indicates that it allows access through a non-terrestrial network, the terrestrial core network determines that it allows the terminal to access the non-terrestrial network. The terrestrial core network further determines the PLMN ID of at least one non-terrestrial network that the terminal is allowed to access based on the terminal's subscription information and the roaming agreement between the operator of the terrestrial network currently accessed by the terminal and the operator of the satellite network. The terrestrial core network further determines the identifier of the first network element corresponding to the non-terrestrial network based on the PLMN ID of the at least one non-terrestrial network that the terminal is allowed to access and the location of the terminal.

[0127] In some embodiments, before obtaining the identifier of the first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access, the terrestrial core network receives capability information indicating that the terminal has at least one of the following capabilities: the terminal supports access via a non-terrestrial network cell, the terminal supports handover from a terrestrial cell to a non-terrestrial network cell, or the terminal supports redirection from a terrestrial cell to a non-terrestrial network cell. Accordingly, the terminal sends the capability information, or in other words, the terminal sends the capability information to the terrestrial core network.

[0128] In this way, when the terrestrial core network determines that the terminal supports access to a non-terrestrial network cell, it can identify the non-terrestrial network that supports the terminal's access and the first network element corresponding to the non-terrestrial network, so that the first network element can provide auxiliary information for the terminal to switch from the terrestrial network to the non-terrestrial network.

[0129] 402. The terrestrial core network sends a first instruction message, which is used to instruct the terminal to obtain auxiliary information. Alternatively, the terrestrial core network sends a second instruction message, which includes an identifier of a first network element, and the identifier of the first network element is used to instruct the terminal to obtain auxiliary information from the first network element. Alternatively, the terrestrial core network sends a ninth instruction message, which includes an identifier of at least one non-terrestrial network that the terminal is allowed to access, and an identifier of the first network element, and the identifier of the first network element is used by the terminal's terrestrial network service equipment to obtain auxiliary information from the first network element.

[0130] The role and content of the auxiliary information are explained in step 301.

[0131] In some embodiments, the terrestrial core network sending the first indication information includes: the terrestrial core network sending the first indication information to the terminal. Correspondingly, the terminal receives the first indication information sent by the terrestrial core network. In this case, the terrestrial core network may obtain auxiliary information from a determined first network element and send the auxiliary information to the terminal through the first indication information, so that the terminal can access the target non-terrestrial network cell when moving out of or about to move out of the coverage of the terrestrial network based on the auxiliary information.

[0132] In some embodiments, the terrestrial core network sending the second indication information includes: the terrestrial core network sending the identifier of a first network element to the terminal. Correspondingly, the terminal receives the identifier of the first network element. The second indication information may include one or more non-terrestrial network PLMN IDs and the identifier of the first network element corresponding to the non-terrestrial network. Thus, the terminal can request auxiliary information from the first network element based on the identifier of the first network element, so that the terminal can access a target non-terrestrial network cell when moving out of or about to move out of the coverage of the terrestrial network. When multiple non-terrestrial networks exist, the terminal can determine one of the multiple non-terrestrial networks and request auxiliary information from the first network element corresponding to that non-terrestrial network; alternatively, the terminal can request auxiliary information from the first network element corresponding to each non-terrestrial network. In this embodiment, in addition to sending the second indication information to the terminal, the terrestrial core network can also send tenth indication information to the serving network equipment of the terrestrial network, indicating that the terminal is allowed to switch from the terrestrial network to a non-terrestrial network. The tenth indication information includes the identifier of at least one non-terrestrial network that the terminal is allowed to access. In this way, the service network equipment, such as the ground base station, can determine, based on the tenth indication information, whether the terminal is allowed to hand over to the target non-terrestrial network cell determined by the terminal, or the ground base station can determine the target non-terrestrial network cell based on the tenth information and the measurement results of the non-terrestrial network cell, and initiate the process of handing over the ground cell to the non-terrestrial network cell.

[0133] In some embodiments, the terrestrial core network sending the ninth indication information includes: the terrestrial core network sending the ninth indication information to the serving network device of the terrestrial network. Correspondingly, the serving network device receives the ninth indication information sent by the terrestrial core network. In this case, in some embodiments, when the serving network device is a terrestrial base station, the terrestrial base station can obtain auxiliary information from the first network element based on the identifier of the first network element and send it to the terminal, so that the terminal can determine the target non-terrestrial network cell. In this embodiment, when the terminal is in an idle state, the terminal always determines the target non-terrestrial network cell based on the auxiliary information; when the terminal is in a connected state, the terminal can determine the target non-terrestrial network cell based on the auxiliary information. In other embodiments, when the terminal is in a connected state, the terrestrial base station can obtain auxiliary information from the first network element based on the identifier of the first network element, determine candidate satellite cells or beams, and send the auxiliary information of the candidate satellite cells or beams to the terminal for measurement. The terrestrial base station determines the target non-terrestrial network cell based on the measurement results.

[0134] Therefore, for the terrestrial core network accessed by the terminal, the terminal can obtain auxiliary information for switching from the terrestrial network to a non-terrestrial network by indicating the auxiliary information provided by the first network element or the identifier of the first network element of the terrestrial network. Alternatively, the serving network device can obtain auxiliary information from the first network element and send it to the terminal by indicating the identifier of the first network element, or the serving network device can determine candidate satellite cells or beams based on the auxiliary information obtained from the first network element, so that the terminal can initiate cell measurement and feed back the measurement results to the serving network device to determine the target non-terrestrial network cell. In this way, this application addresses the situation where neighbor cell information cannot be configured between the non-terrestrial network and the terrestrial network. The auxiliary information provided by the first network element can support the terminal to switch from the terrestrial cell to the non-terrestrial network cell, and the terminal does not need to frequently perform frequency point searches, saving terminal power consumption.

[0135] For a first network element in a non-terrestrial network, the first network element can receive a request from a terrestrial core network, a terminal, or a terrestrial base station to request auxiliary information for the terminal to switch from a terrestrial network to a non-terrestrial network. The first network element can then send the auxiliary information to the terrestrial core network, the terminal, or the terrestrial base station. Figure 5 shows a flowchart of a communication method provided in this application, which includes the following steps.

[0136] 501. The first network element receives third indication information, which is used to request auxiliary information. The auxiliary information is used for the terminal to access a non-terrestrial network from a terrestrial network. The third indication information includes the terminal's location information.

[0137] The auxiliary information includes the contents described in step 301.

[0138] 502. The first network element sends a first instruction message, which includes auxiliary information.

[0139] The first network element determines auxiliary information based on the terminal's location information. The satellite coverage area in the auxiliary information includes the terminal's location, as does the coverage area of ​​the satellite cell or satellite beam.

[0140] In some embodiments, step 501, receiving the third indication information by the first network element includes: the first network element receiving the third indication information sent by the terminal. Accordingly, the terminal sends the third indication information to the first network element. Step 502, sending the first indication information by the first network element includes: the first network element sending the first indication information to the terminal. Accordingly, the terminal receives the first indication information sent by the first network element. In this case, the terminal can determine the target non-terrestrial network cell based on the auxiliary information indicated by the first indication information.

[0141] In some embodiments, step 501, receiving the third indication information by the first network element includes: the first network element receiving the third indication information sent by the serving network device of the terrestrial network. Correspondingly, the serving network device of the terrestrial network sends the third indication information to the first network element. Step 502, sending the first indication information by the first network element includes: the first network element sending the first indication information to the serving network device. Correspondingly, the serving network device receives the first indication information sent by the first network element. In this case, the serving network device of the terrestrial network, i.e., the source terrestrial base station, can determine candidate satellite cells or beams based on the auxiliary information indicated by the first indication information, so as to instruct the terminal to measure the candidate satellite cells or beams and determine the target non-terrestrial network cell. Alternatively, the source terrestrial base station can send the auxiliary information indicated by the first indication information to the terminal, so that the terminal can measure the non-terrestrial network cell or determine the target non-terrestrial network cell based on the auxiliary information.

[0142] In some embodiments, step 501, receiving the third indication information by the first network element includes: the first network element receiving the third indication information sent by the terrestrial core network. Correspondingly, the terrestrial core network sends the third indication information to the first network element. Step 502, sending the first indication information by the first network element includes: the first network element sending the first indication information to the terrestrial core network. Correspondingly, the terrestrial core network receives the first indication information sent by the first network element. In this case, the terrestrial core network can send the auxiliary information carried in the first indication information to the terminal, which can then use the auxiliary information to measure or determine the target non-terrestrial network cell.

[0143] Therefore, for the first network element in the non-terrestrial network, upon receiving the third instruction information requesting auxiliary information, it can provide auxiliary information for the terminal to switch from the terrestrial network to the non-terrestrial network. In this way, for situations where neighbor cell information cannot be configured between the non-terrestrial and terrestrial networks, this application can support the terminal to switch from a terrestrial cell to a non-terrestrial network cell through the auxiliary information provided by the first network element. Moreover, the terminal does not need to frequently perform frequency point searches, saving terminal energy consumption.

[0144] For the serving network equipment of the terminal on the terrestrial network, i.e., the source terrestrial base station, it can obtain from the terrestrial core network an indication that the terminal is allowed to switch from the terrestrial network to a non-terrestrial network, as well as the identifier of the non-terrestrial network that the terminal is allowed to access. In this way, the source terrestrial base station can determine which network allows the terminal to switch to the target non-terrestrial network, or, with the aid of auxiliary information, determine candidate non-terrestrial network cells to instruct the terminal to perform measurements on the non-terrestrial network. Figure 6 shows a flowchart of a communication method provided in an embodiment of this application, which includes the following steps.

[0145] 601. The service network equipment of the terrestrial network receives the tenth instruction information, which is used to indicate that the terminal is allowed to switch from the terrestrial network to a non-terrestrial network. The tenth instruction information includes the identifier of at least one non-terrestrial network that the terminal is allowed to access.

[0146] In some embodiments, the service network device of the terrestrial network receiving the tenth indication information includes: the service network device receiving the tenth indication information sent by the terrestrial core network. Accordingly, the terrestrial core network sends the tenth indication information to the service network device.

[0147] Thus, when the serving network device receives the tenth instruction information, it can determine whether to allow the terminal device to switch from the terrestrial cell to the target non-terrestrial network cell when it receives the fourth instruction information sent by the terminal, or it can determine the target non-terrestrial network cell based on the tenth instruction information when it receives the fifth instruction information sent by the terminal.

[0148] In some embodiments, the tenth indication information further includes the identifier of at least one first network element corresponding to a non-terrestrial network. Thus, the serving network device can also obtain auxiliary information from the first network element based on its identifier. The serving network device can determine candidate non-terrestrial network cells based on the auxiliary information to instruct the terminal to measure the candidate non-terrestrial network cells.

[0149] 602. The serving network device receives a fourth indication information or a fifth indication information, wherein the fourth indication information includes the identifier of a target non-terrestrial network cell in at least one non-terrestrial network, and the fifth indication information includes the measurement results of at least one candidate non-terrestrial network cell in at least one non-terrestrial network, and the measurement results are used to determine the target non-terrestrial network cell.

[0150] In some embodiments, the serving network device receiving the fourth or fifth indication information includes: the serving network device receiving the fourth or fifth indication information sent by the terminal. Accordingly, the terminal sends the fourth or fifth indication information to the serving network device.

[0151] In some embodiments, the serving network device instructs the terminal to measure candidate non-terrestrial network cells, thereby receiving fifth instruction information from the terminal device.

[0152] When the serving network device receives the fifth indication information, it can determine the target non-terrestrial network cell based on the measurement results of the non-terrestrial network cell.

[0153] In other words, the target non-terrestrial network cell can be determined by the terminal based on the measurement results of the non-terrestrial network cell, and then the terminal can indicate the target non-terrestrial network cell to the serving network device. Alternatively, the target non-terrestrial network cell can be determined by the serving network device based on the measurement results.

[0154] 603. The service network device initiates a process to switch the terminal to the target non-terrestrial network cell based on the fourth or fifth instruction information.

[0155] When the serving network device initiates a process to switch the terminal to a target non-terrestrial network cell, the terminal can be switched from a terrestrial cell to the target non-terrestrial network cell. In this way, when the terminal leaves or is about to leave the coverage of the terrestrial network, it can be switched to the non-terrestrial network in a timely manner.

[0156] Therefore, in this application, the serving network equipment of the terminal on the terrestrial network can, based on determining the identifier of at least one non-terrestrial network that the terminal is allowed to access, assist the terminal in initiating a process of switching from a terrestrial cell to a target non-terrestrial network cell when determining the measurement results of the target non-terrestrial network cell. In this way, this application addresses the situation where neighbor cell information cannot be configured between non-terrestrial and terrestrial networks. It supports the terminal switching from a terrestrial cell to a non-terrestrial network cell through the serving network equipment of the terrestrial network, and the terminal does not need to frequently perform frequency point searches, saving terminal energy consumption.

[0157] Based on the above introduction of various network elements, namely the terminal, the terrestrial core network, the first network element of the non-terrestrial network, and the service network equipment of the terrestrial network, the signaling interaction process of the communication method of this application will be described below in conjunction with the implementation of the above network elements.

[0158] Figure 7 shows a flowchart of a communication method provided in an embodiment of this application. In this method, when the ground core network determines a non-terrestrial network that supports terminal access and the corresponding first network element, the ground core network requests auxiliary information from the first network element and sends it to the base station; or the ground core network sends the identifier of the first network element to the terminal, and the terminal requests auxiliary information from the first network element; or the ground core network sends the identifier of the first network element to the serving network device of the ground network, and the serving network device requests auxiliary information from the first network element and sends it to the terminal. Thus, when the terminal is idle, it can search for non-terrestrial network cells based on the auxiliary information and determine the target non-terrestrial network cell for access. The method of this application will be exemplarily described below using the serving network device of the ground network as the source ground base station, the non-terrestrial network as a satellite network, and the target non-terrestrial network cell as the target satellite base station. The method includes the following steps.

[0159] 701. The terminal registers with the ground core network and sends its capability information to the ground core network.

[0160] For example, when a terminal initiates a registration process with the terrestrial core network through the source terrestrial base station, the registration request message sent by the terminal to the terrestrial core network includes the terminal's capability information.

[0161] Alternatively, the terminal's capability information can be carried in messages such as attach request messages or service request messages sent by the terminal to the ground core network through the source ground base station.

[0162] Alternatively, in future communication networks, the registration request message may be other messages, and this application does not impose any restrictions.

[0163] Alternatively, the capability information can be carried in a dedicated request message for the sending terminal's capabilities.

[0164] 702. The terrestrial core network determines which terminals are allowed to access the network via a non-terrestrial network, and identifies the non-terrestrial networks that support terminal access and the first network element corresponding to the non-terrestrial network.

[0165] In some embodiments, when the terrestrial core network determines that a terminal is allowed to access the network through a non-terrestrial network, it may obtain the identifier of a first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access.

[0166] For example, the terrestrial core network can be an AMF network element in the terrestrial core network, or it can be other terrestrial core network elements.

[0167] For example, the terrestrial core network can determine whether to allow the terminal to access the network through a non-terrestrial network, or through a non-terrestrial base station, by using the terminal's subscription information, terminal capability information, terminal current location information, and roaming agreements between satellite operators and terrestrial operators. It can also determine the identifier of the non-terrestrial network that the terminal is allowed to access, i.e., the PLMN ID of the non-terrestrial network, which can also be understood as the PLMN ID of the satellite network.

[0168] For example, the terminal's current location information can be reported by the terminal to the ground core network, or it can be the terminal's location determined by the ground base station based on the ground cell information currently accessed by the terminal. For example, the terminal's ground cell information includes the terminal's location information, which can be the identifier and / or tracking area identifier of the currently accessed ground cell. The ground base station can send the terminal's location to the ground core network. For example, the terminal's location can be the geographical area information where the terminal is currently located, or even the terminal's two-dimensional geographic coordinates or latitude and longitude, or the identifier and / or tracking area identifier of the ground cell. This application does not limit the accuracy of the terminal's geographic coordinates.

[0169] When the terminal's home network is a satellite operator, and the terminal's location has terrestrial coverage from the terminal's home operator, the terrestrial core network determines the satellite networks that the terminal is allowed to access, including the terminal's home operator, based on roaming support between the terrestrial network operator and the home operator. For example, the terminal's home operator is a satellite operator.

[0170] When a terminal's subscription information supports roaming across satellite operators, the terminal can also access the network through a satellite base station of a satellite operator with which both its home operator and the currently accessing terrestrial operator have roaming agreements, and which has non-terrestrial coverage at its current location. In this case, the terrestrial core network can identify the satellite operator as a non-terrestrial PLMN that the terminal is allowed to access.

[0171] If the terminal's home operator is a terrestrial operator, the terminal's subscription information may include an indication of whether the terminal is allowed to access the network via satellite. In this case, the terrestrial core network can determine whether to allow the terminal to access the network via satellite based on the terminal's subscription information, and select a satellite operator that has a roaming agreement with the terrestrial operator and has terrestrial coverage at the current location as the non-terrestrial PLMN that allows the terminal to access the network.

[0172] In this way, the terrestrial core network can identify one or more non-terrestrial PLMNs that terminals are allowed to access. When a terminal's current location has a home PLMN (HPLMN), the HPLMN is included in the non-terrestrial PLMNs that terminals are allowed to access. If other PLMNs exist at the terminal's current location, and the terminal supports roaming, the terrestrial core network can also identify these other PLMNs as non-terrestrial PLMNs that terminals are allowed to access.

[0173] The terrestrial core network can prioritize the non-terrestrial PLMNs that are allowed for terminal access. For example, HPLMNs can be set as the highest priority, so that the satellite base station of the HPLMN of the terminal can be preferred for access.

[0174] After identifying the non-terrestrial PLMNs that are allowed for terminal access, the terrestrial core network determines the first network element corresponding to the non-terrestrial PLMN, or in other words, determines the topology service corresponding to the non-terrestrial PLMN. When there are multiple non-terrestrial PLMNs that are allowed for terminal access, the terrestrial core network can also determine the first network element corresponding to each non-terrestrial PLMN that is allowed for terminal access.

[0175] For example, different non-terrestrial PLMNs can correspond to different first network elements, or they can share the same first network element.

[0176] Having identified the non-terrestrial networks that support terminal access and the corresponding first network elements, this application provides three exemplary methods for terminals to obtain auxiliary information.

[0177] Method 1: The terrestrial core network obtains auxiliary information from the first network element and sends it to the terminal. For Method 1, please refer to steps 703-710.

[0178] 703. The ground core network sends a third instruction message, which is used to request the first network element to provide auxiliary information. The third instruction message includes the terminal's location information.

[0179] In some embodiments, the terrestrial core network sending the third indication information includes: the terrestrial core network sending the third indication information to the first network element. Correspondingly, the first network element receives the third indication information sent by the terrestrial core network.

[0180] If the ground core network identifies multiple first network elements, the ground core network can send third instruction information to each of the multiple first network elements to obtain auxiliary information fed back by the multiple first network elements.

[0181] For example, the third indication information includes the terminal's area information or location information. The area information indicates the area covered by the satellite cell requested by the terminal, or in other words, the area where the terminal is located. For example, the area information indicates a circular area centered on the terminal's location (e.g., latitude and longitude), or a square or rectangular area originating from the terminal's location (e.g., latitude and longitude). The area indicated by the terminal's area information can also be of other shapes, such as an equilateral polygon; this application does not limit this, nor does it limit the relationship between the terminal and the area, i.e., it does not limit whether the terminal is located at the center or edge of the area.

[0182] For example, the third indication information does not include area information, but includes the terminal's location information. For example, the first network element determines the area information based on the location information. For instance, the location information indicates the terminal's latitude and longitude coordinates. When the terminal's location information is a ground cell identifier and / or a tracking area identifier, the ground core network can convert the terminal's location information into geographic location information, such as latitude and longitude information, and the third indication information includes the terminal's geographic location information.

[0183] 704. The first network element sends a first instruction message, which includes auxiliary information.

[0184] In some embodiments, the first network element sending the first indication information includes: the first network element sending the first indication information to the ground core network. Correspondingly, the ground core network receives the first indication information sent by the first network element.

[0185] In some embodiments, the first network element is a network element in the satellite core network of the satellite network, or the first network element is a network element in the terrestrial core network of the satellite network. The first network element can be understood as a satellite topology service.

[0186] In some embodiments, the auxiliary information is determined by the first network element based on the terminal's location information, the satellite constellation information of the satellite network, the configuration information of each satellite in the satellite network, and the current time information.

[0187] For example, the first network element stores satellite constellation information of the satellite network (corresponding to multiple non-terrestrial PLMNs). For instance, the satellite constellation information indicates the orbital information of the satellites, such as the number and distribution of orbits, orbital altitude, orbital inclination, number of satellites in each orbit, and their distribution.

[0188] In some embodiments, the first network element also stores configuration information for each satellite in the plurality of satellites in the network. For example, this configuration information includes the satellite's coverage area on the ground (in a constellation, satellites with the same orbital altitude and inclination typically have the same coverage area information). For example, Figure 8 shows a schematic diagram of the coverage area information for satellite A. The coverage area information includes the angle between the satellite's coverage edge line B and the geocentric line C, which is, for example, 40.45 degrees as shown in Figure 8, where the perpendicular line from satellite A to the ground shown in Figure 8 is the geocentric line C, which is the line connecting satellite A and the Earth's center of mass. Alternatively, the coverage area information could also be the elevation angle of satellite A, i.e., the angle between the line DA connecting observer D and satellite A and the horizon E, as shown in Figure 8, which is 40 degrees.

[0189] The first network element can determine the current satellite distribution and the geographical area covered by each satellite in the constellation based on the satellite constellation information and coverage information of each satellite network. The satellite distribution refers to the position of each satellite in the satellite network at the current moment, for example, the satellite's coordinates in the Earth coordinate system.

[0190] The first network element determines which satellites cover the terminal's location at the current moment based on the terminal's location information, the current satellite distribution information in the satellite network, and the coverage information of each satellite. The first network element can also select multiple future moments and calculate which satellites will cover the current terminal's location at a future moment. In this way, the first network element can obtain the satellites covering the terminal's current location at multiple moments.

[0191] In some embodiments, the configuration information of each satellite in the multiple satellite networks stored by the first network element also includes beam configuration information. For example, the beam configuration information indicates the number of beams on each satellite, the identifier of each beam on each satellite, the area covered by each beam on each satellite within the satellite coverage area, and the scanning rules of the beam within the satellite coverage area. The first network element can determine the beam identifier covering the terminal location at a certain time based on the satellite beam configuration information, such as the area covered by the beam within the satellite coverage area and the number of beams on the satellite.

[0192] For example, Figure 9 illustrates a schematic diagram of satellite beam distribution on the ground. Figure 9 shows the distribution of satellite beams on the ground when a satellite has eight downlink beams and a coverage radius of 500 km. It can be understood that since the satellite has eight downlink beams, each beam covers an area with a radius of approximately 20-25 km. These eight downlink beams need to scan within the satellite's coverage area to cover the entire area; that is, the satellite can perform beam scanning according to certain rules. In Figure 9, each hexagonal area can be understood as the coverage area of ​​a downlink beam, the numbers in the hexagons can be understood as the identifiers of the downlink beams, and the circular areas represent the coverage area or coverage range of the satellite. In some examples, the first network element can also store the beam scanning rules of the satellite within its coverage area, thereby determining the beam identifier of a specific location within the coverage area of ​​the serving satellite and the time slot for that beam to serve that area based on the beam scanning rules. It can be understood that this time slot is one or more time slots within the time slice in which the satellite covers the area; the time slot can be described using time relative to the time slice.

[0193] In some embodiments, the beam configuration information of each satellite may further include radio configuration information for each beam. For example, this radio configuration information may include information such as the center frequency of the beam.

[0194] Thus, the first network element can further determine the beam elevation angle, or satellite elevation angle, of the terminal's current location at a certain moment based on the terminal's location information, the satellite constellation information of the satellite network, the configuration information of each satellite in the satellite network, and the current time information. For example, this can be understood as 40 degrees as shown in Figure 8. The beam elevation angle helps align the directional terminal antenna with the beam to achieve higher wireless gain. Correspondingly, the auxiliary information also includes beam elevation angle information, which is used by the terminal antenna to align with the beam for receiving and transmitting data. In some embodiments, the terminal determines the beam elevation angle based on the auxiliary information. For example, the terminal calculates the beam elevation angle based on the satellite ephemeris information, the current time information, and the terminal's location information in the auxiliary information, and then performs beam alignment based on the beam elevation angle.

[0195] Therefore, for the first network element, the auxiliary information of the terminal determined by the first network element may include information of at least one satellite covering the location of the terminal. The information of at least one satellite includes at least one of the following: satellite identifier, satellite ephemeris information, time information, satellite coverage information, and information of at least one cell or beam of the satellite.

[0196] For any one of the at least one satellites, the cell or beam information of that satellite includes at least one of the following: the identifier of the satellite cell or beam, the frequency information of the satellite cell or beam, the scanning period of the satellite cell or beam, the scanning time slot of the satellite cell or beam, the coverage information of the satellite cell or beam, or the effective time of the satellite cell or beam information. The frequency information can be understood as the aforementioned center frequency. The scanning period, time slot, and effective time of the satellite cell or beam can be determined according to the satellite beam scanning rules. The coverage information of the satellite cell or beam is the coverage area information of each beam on the satellite within the satellite's coverage area, or it can be understood as the effective area or effective geographical range of each beam within the satellite's coverage area.

[0197] The first network element can determine the auxiliary information of the terminal at a certain time at its current location in the manner described above. The first network element can also determine the auxiliary information of the terminal at multiple times at its current location. This is because the satellites covering the terminal's current location may be different at different times, and the first network element can determine the auxiliary information of the terminal at its current location at different times based on the information of the satellite constellation.

[0198] 705. The effective time of satellite cell or beam coverage information and satellite cell or beam information recorded in the auxiliary information of the ground core network.

[0199] When the ground core network receives auxiliary information sent by the first network element, the auxiliary information includes the coverage information of the satellite cell or beam and the validity time of the satellite cell or beam information. The ground core network records the coverage information and the validity time. The validity time can be used to determine whether the auxiliary information is valid. The coverage information can be used to determine whether the terminal has moved out of the valid area of ​​the satellite cell or beam after the terminal moves. If the terminal moves out of or is about to move out of the valid area of ​​any satellite cell or beam whose validity time in the auxiliary information includes the current time, or if the validity time of any satellite cell or beam in the auxiliary information does not include the current time, the auxiliary information is invalid, and the ground core network can request the first network element to update the auxiliary information. This involves executing steps 707-710.

[0200] 706. The ground core network sends a first instruction message to the terminal, which includes auxiliary information.

[0201] Accordingly, the terminal receives the first indication information sent by the ground core network. In this way, the terminal can perform satellite cell or beam search in idle state based on auxiliary information to determine the target non-terrestrial network cell.

[0202] 707. When the ground core network determines that a terminal has moved out of or is about to move out of the coverage area of ​​any one of the at least one satellites in the auxiliary information, or when it determines that the terminal has moved out of or is about to move out of the coverage area of ​​the cell or beam of any one of the at least one satellites, or when it determines that the validity period of the cell or beam information of any one of the at least one satellites has expired or is about to expire.

[0203] For example, the ground core network can periodically acquire the terminal's location information (or area information) and determine whether the terminal has moved out of the coverage area of ​​any satellite indicated by the auxiliary information, or the coverage area of ​​any satellite's cell or beam. If it is determined that the terminal's auxiliary information is geographically invalid, i.e., the terminal has moved out of or is about to move out of the coverage area of ​​any satellite indicated by the auxiliary information, or the coverage area of ​​any satellite's cell or beam, the ground core network can execute step 708. Alternatively, the ground core network can determine that the terminal's auxiliary information is temporally invalid based on the validity time of any satellite's cell or beam information, i.e., the validity time of any satellite's cell or beam information does not include the current time, and the ground core network can execute step 708. This ensures that the terminal's auxiliary information remains valid both geographically and temporally, so that the terminal can obtain valid auxiliary information and select and access non-terrestrial networks based on the auxiliary information.

[0204] This is because, as the terminal moves, the coverage area of ​​any cell or beam of at least one of the previously acquired satellites may no longer cover the area where the terminal's latest updated location is located. Therefore, the ground core network can request the first network element to update the auxiliary information, i.e., execute step 708.

[0205] 708. The ground core network sends first information, which is used to request the first network element to update auxiliary information. The first information includes the terminal's current location information.

[0206] In some embodiments, the terrestrial core network sending the first information includes: the terrestrial core network sending the first information to a first network element. Correspondingly, the first network element receives the first information sent by the terrestrial core network.

[0207] For instructions on how to update auxiliary information in the ground core network, please refer to step 704.

[0208] In some embodiments, when the first network element determines that the information of any satellite cell or beam in the previously transmitted auxiliary information has changed, or when the first network element determines that the previously transmitted auxiliary information has expired, the first network element actively updates the satellite cell or beam information to the terminal. That is, in this embodiment, the terminal does not send the first information, i.e., it does not execute step 708. For example, changes in satellite cell or beam information may also be caused by satellite operator deployments, such as the satellite operator adding satellite cells or beams or adjusting the configuration of satellite cells or beams.

[0209] 709. The first network element sends the second information, which indicates the updated auxiliary information.

[0210] In some embodiments, the first network element sending the second information includes: the first network element sending the second information to the ground core network. Correspondingly, the ground core network receives the second information sent by the first network element.

[0211] 710. The ground core network sends third information, which is used to indicate the updated auxiliary information to the terminal. Then, step 718 is executed.

[0212] In some embodiments, the terrestrial core network sending third information includes: the terrestrial core network sending third information to the terminal. Accordingly, the terminal receives the third information sent by the terrestrial core network.

[0213] In this way, the terminal can search for satellite cells or beams in idle state based on the updated auxiliary information to identify target non-terrestrial network cells.

[0214] Method 2: The terminal obtains auxiliary information from the first network element. For Method 2, please refer to steps 711-713.

[0215] 711. The ground core network sends a second instruction message, which includes the identifier of the first network element. The identifier of the first network element is used by the terminal to obtain auxiliary information from the first network element.

[0216] In some embodiments, the terrestrial core network sending the second indication information includes: the terrestrial core network sending the second indication information to the terminal. Accordingly, the terminal receives the second indication information sent by the terrestrial core network.

[0217] For example, if the terrestrial core network determines that there are multiple non-terrestrial networks that the terminal is allowed to access, or can be understood as having multiple non-terrestrial PLMNs, the second indication information may include multiple non-terrestrial PLMN IDs (PLMN IDs of multiple satellite networks) and the identifier of the first network element corresponding to each non-terrestrial PLMN.

[0218] For example, the identifier of the first network element may be, for example, the IP address or FQDN of the first network element.

[0219] 712. The terminal sends a third instruction message, which is used to request the first network element to provide auxiliary information. The third instruction message includes the terminal's location information.

[0220] In some embodiments, the terminal sending the third indication information includes: the terminal sending the third indication information to the first network element. Accordingly, the first network element receives the third indication information sent by the terminal.

[0221] 713. The first network element sends a first indication message, which includes auxiliary information. Then, step 718 is executed.

[0222] In some embodiments, the first network element sending the first indication information includes: the first network element sending the first indication information to the terminal. Accordingly, the terminal receives the first indication information sent by the first network element.

[0223] The method for determining auxiliary information for the first network element can be found in the description in step 704.

[0224] Method 3: The source ground base station of the terrestrial network obtains auxiliary information and sends it to the terminal.

[0225] 714. The terrestrial core network sends a ninth instruction message, which includes the identifier of at least one non-terrestrial network that the terminal is allowed to access and the identifier of a first network element. The identifier of the first network element is used by the terminal's terrestrial network service network equipment to obtain auxiliary information from the first network element.

[0226] In some embodiments, the terrestrial core network sending the ninth indication information includes: the terrestrial core network sending the ninth indication information to the source terrestrial base station. Correspondingly, the source terrestrial base station receives the ninth indication information sent by the terrestrial core network.

[0227] For example, the ninth indication information includes an identifier of at least one satellite network that the terminal is allowed to access, and an identifier of the first network element corresponding to the satellite network. The identifier of the satellite network is, for example, the PLMN ID of the satellite network.

[0228] 715. The source ground base station sends a third indication message to the first network element. The third indication message is used to request auxiliary information.

[0229] Accordingly, the first network element receives the third indication information sent by the source ground base station.

[0230] That is, the source ground base station can request auxiliary information from the first network element based on the identifier of the first network element in step 714. The third indication information may include the terminal's location information. Specifically, the source ground base station can determine the terminal's location information based on the cell identifier and / or tracking area identifier of the ground base station to which the terminal is connected. The terminal's location information may be the terminal's geographical coordinates, such as latitude and longitude.

[0231] 716. The first network element sends a first indication message to the source ground base station, the first indication message including auxiliary information.

[0232] The method for determining auxiliary information for the first network element can be found in the description in step 704.

[0233] 717. The source ground base station sends a first indication message to the terminal, the first indication message including auxiliary information.

[0234] 718. The terminal searches for non-terrestrial network cells based on auxiliary information.

[0235] In some embodiments, the terminal determines the cells or beams of at least a portion of the satellites based on auxiliary information, i.e., determines the cells or beams of candidate satellites, performs downlink synchronization, and measures the cells or beams of the candidate satellites to obtain measurement results. Based on the measurement results, the terminal determines the target non-terrestrial network cell from the cells or beams of the candidate satellites.

[0236] If a terminal receives multiple auxiliary information messages from different times simultaneously, considering the validity period of the auxiliary information, including information about the satellite's cell or beam, the terminal can determine the auxiliary information to be used based on the validity period.

[0237] For example, if the auxiliary information includes the elevation angle of the satellite beam, the terminal can adjust the antenna direction based on the elevation angle in the auxiliary information. Alternatively, if the auxiliary information does not include the elevation angle of the satellite beam, the terminal calculates the beam elevation angle based on the ephemeris information of the satellite corresponding to the target non-terrestrial network cell, the terminal's location, and the current time, and adjusts the antenna direction accordingly. When the auxiliary information includes the beam scanning time slot, the terminal can determine the downlink synchronization time for the beam based on the beam scanning time slot and measure the downlink signal strength to determine whether access to the beam is possible.

[0238] If, after downlink synchronization and measurement with a candidate satellite cell or beam, the measurement results meet preset selection criteria, the terminal can use that satellite cell or beam as the target non-terrestrial network cell. The terminal can then stop downlink synchronization and measurement with the remaining satellite cells and beams to conserve terminal power. A satellite cell may include the coverage area of ​​one or more beams.

[0239] Then, the terminal can access the target non-terrestrial network cell. In some embodiments, terminal access to the target non-terrestrial network cell includes: the terminal camping on the target non-terrestrial network cell; or, the terminal receiving and / or sending signaling and / or data through the target non-terrestrial network cell. Alternatively, the terminal sends fourth indication information, the fourth indication information including the identifier of the target non-terrestrial network cell, the fourth indication information being used to instruct the terminal's serving network device on the terrestrial network to initiate a process of switching the terminal to the target non-terrestrial network cell.

[0240] The target non-terrestrial network cell can be a cell under a satellite, or a cell within the coverage area of ​​a single beam under a satellite.

[0241] The terminal's presence in the target non-terrestrial network cell can be understood as the terminal monitoring or receiving broadcast messages from the target non-terrestrial network cell in the idle state, as well as monitoring or receiving paging messages in the target non-terrestrial network cell.

[0242] When a terminal receives and / or sends signaling and / or data through a target non-terrestrial network cell, it can be understood as the terminal sending and receiving signaling and / or data in the target non-terrestrial network cell while in connected mode. That is, the terminal can initiate signaling procedures, such as registration / update procedures, through the target satellite base station of the target non-terrestrial network cell; or, the terminal can send and receive data, such as for home internet access, through the target non-terrestrial network cell.

[0243] The terminal may send a fourth indication message, instructing the source terrestrial base station to initiate a process of switching the terminal to a target non-terrestrial network cell. This allows the terminal to promptly access the target satellite base station when leaving or about to leave terrestrial network coverage, enabling the target non-terrestrial network cell to provide services to the terminal.

[0244] Thus, for the terminal, when moving from or about to move to an area without terrestrial cell coverage, it can measure the satellite cell or beam based on auxiliary information received from the first network element of the satellite network to determine the target satellite cell. Compared to existing solutions where cross-operator support for configuring neighbor cell information is not supported if the satellite cell and terrestrial cell belong to different operators, preventing handover from terrestrial to satellite cells, this application assists the terminal in measuring the satellite cell or beam using auxiliary information provided by the first network element of the satellite network, enabling the terminal to access a satellite cell from a terrestrial cell. Furthermore, in idle mode, the terminal does not need to perform a full-frequency search within a certain range when searching for satellite cells, saving terminal power.

[0245] Figure 10 illustrates a flowchart of a communication method. In this method, a terminal can switch satellite cells or beams while in a connected state. If the ground core network determines the satellite networks that the terminal is allowed to access and the corresponding first network element, the ground core network can instruct the source ground base station on the satellite networks that the terminal is allowed to access and indicate the identifier of the first network element to the terminal. When the terminal obtains auxiliary information based on the identifier of the first network element and determines the target satellite cell, it can request a handover to the target satellite cell from the source ground base station. When the source ground base station determines that the terminal is allowed to switch to the target satellite cell based on the satellite networks that the terminal is allowed to access, it initiates the handover procedure. This method includes the following steps.

[0246] 101. The terminal registers with the ground core network and carries the terminal's capability information in the registration request.

[0247] For details on how to implement step 101, please refer to the description of step 701.

[0248] 102. The terrestrial core network determines which terminals are allowed to access the network through non-terrestrial networks, and identifies the non-terrestrial networks that support terminal access and the first network element corresponding to the non-terrestrial networks.

[0249] For details on how to implement step 102, please refer to the description in step 702.

[0250] 103. The terrestrial core network sends a tenth instruction message to the source terrestrial base station. The tenth instruction message is used to instruct the source terrestrial base station to allow the terminal to switch from the terrestrial network to the satellite network. The tenth instruction message includes the identifier of at least one satellite network that the terminal is allowed to access.

[0251] Accordingly, the source ground base station receives the tenth indication information sent by the ground core network. In other words, the tenth indication information is used by the source ground base station to determine which base station the terminal is permitted to hand over to the target non-terrestrial network cell.

[0252] For example, the tenth indication information includes the PLMN ID of at least one satellite network that the terminal is allowed to access.

[0253] 104. The ground core network sends a second instruction message to the terminal. The second instruction message includes the identifier of at least one first network element corresponding to the satellite network.

[0254] The implementation method of step 104 can be found in the description of step 711 above.

[0255] 105. The terminal sends a third indication message to the first network element. The third indication message is used to request the first network element to provide auxiliary information. The third indication message includes the terminal's location information.

[0256] The implementation method of step 105 can be found in the description of step 712 above.

[0257] 106. The first network element sends a first instruction message to the terminal, the first instruction message being used to instruct the terminal on auxiliary information.

[0258] The implementation method of step 106 can be found in the description of step 713 above.

[0259] 107. The source ground base station sends a sixth indication message to the terminal. The sixth indication message is used to indicate that the terminal has moved out of or is about to move out of the coverage area of ​​the ground network, or the sixth indication message is used to indicate that the terminal performs measurements on the non-ground network.

[0260] Accordingly, the terminal receives the sixth indication information sent by the source ground base station.

[0261] In some embodiments, before sending the sixth indication information, the method further includes: the source ground base station determining that the terminal has moved out of or is about to move out of the coverage area of ​​the ground network.

[0262] For example, if the source ground base station determines, according to step 103, that the terminal is allowed to switch from the terrestrial network to the satellite network, and if the source ground base station determines, based on the terminal's location, that the terminal has left or is about to leave the cell coverage area of ​​the source ground base station, and the source ground base station determines that there are no other neighboring terrestrial cells available, the source ground base station determines that the terminal has moved out of or is about to move out of the terrestrial network coverage area. In this case, the source ground base station may send a sixth indication message to the terminal.

[0263] 108. The terminal sends a seventh indication message to the first network element. The seventh indication message is used to request the measurement configuration information of the candidate non-terrestrial network cell from the first network element.

[0264] Correspondingly, the first network element receives the seventh instruction information sent by the terminal.

[0265] For example, when the terminal receives the sixth indication information, it can determine, based on the received auxiliary information and the terminal's location, a candidate satellite cell or beam in the satellite cell or beam indicated by the auxiliary information whose current time slice can cover the terminal's location, or a satellite cell or beam whose current time slice can cover the terminal's location and whose effective coverage time is greater than or equal to a time threshold, so as to perform signal measurement on the candidate satellite cell or beam.

[0266] The method by which the terminal performs signal measurements can be preset. If the terminal performs signal measurements based on broadcast synchronization signals and physical broadcast channel (PBCH) blocks (SSBs), the terminal can skip step 108 and directly perform signal measurements on the satellite cell or beam based on the received SSB. If the terminal performs signal measurements based on non-broadcast signals such as channel state information-reference signals (CSI-RS), the terminal can send seventh indication information to the first network element based on the identifier of the first network element received in step 104 to obtain the measurement configuration information of the candidate satellite cell or beam.

[0267] For example, the seventh indication information includes the identifier of at least one candidate satellite cell or beam and the identifier of the satellite corresponding to the candidate satellite cell or beam.

[0268] 109. The first network element obtains the measurement configuration information of the candidate non-terrestrial network cells.

[0269] For example, if the first network element does not store the measurement configuration information of the candidate satellite cell or beam, the first network element can first obtain the measurement configuration information of the candidate satellite cell or beam. For instance, the first network element can send a request message to the satellite base station corresponding to the candidate satellite cell or beam to request the measurement configuration information. If the measurement signal of the satellite base station is in a turned-off state, the satellite base station can first turn on the measurement signal of the candidate satellite cell or beam, and then feed back the measurement configuration information of the candidate satellite cell or beam to the first network element.

[0270] For example, when performing measurements based on CSI-RS signals, the measurement configuration information may be used to indicate at least one of the following: the frequency of the CSI-RS, the switching timing of the CSI-RS, the period of the CSI-RS, etc.

[0271] 1010. The first network element sends the eighth indication information to the terminal. The eighth indication information includes the measurement configuration information of the candidate satellite cell or beam.

[0272] Accordingly, the terminal receives the eighth instruction information sent by the first network element.

[0273] 1011. The terminal measures the candidate satellite cells or beams and obtains the measurement results.

[0274] In some embodiments, the terminal performs cell measurement on candidate satellite cells or beams, including: performing cell measurement based on at least one of the following information of the candidate satellite cells or beams: frequency point information (e.g., SSB), physical cell identifier (PCI) or measurement configuration information or CSI-RS information.

[0275] For example, if the terminal's antenna is a directional antenna, the terminal can adjust the beam direction according to the direction of the candidate satellite cell or beam, and then perform signal measurement on the satellite cell or beam. Taking 5G NR signal as an example, the terminal can perform satellite cell or beam measurement based on SSB or CSI-RS to obtain the measurement results.

[0276] 1012. The terminal sends a fourth instruction message, which includes the identifier of the target non-terrestrial network cell. This fourth instruction message is used to instruct the serving network equipment on the terrestrial network to initiate a process of handing the terminal over to the target non-terrestrial network cell. Alternatively, the terminal sends a fifth instruction message, which includes measurement results. These measurement results are used by the serving network equipment on the terrestrial network to determine the target non-terrestrial network cell and initiate a process of handing the terminal over to the target non-terrestrial network cell.

[0277] In some embodiments, the terminal may determine the target satellite cell or beam based on the measurement results of step 1011. For example, the terminal may select the satellite cell or beam with the best signal quality among the candidate satellite cells or beams as the target non-terrestrial network cell based on the measurement results. In this case, the terminal may send fourth indication information to the source ground base station, the fourth indication information including the identifier of the target non-terrestrial network cell. The target non-terrestrial network cell is the target satellite cell or beam.

[0278] In some embodiments, when the terminal obtains the measurement results based on step 1011, the terminal may send fifth indication information to the source ground base station. The fifth indication information includes the measurement results of candidate satellite cells or beams. The source ground base station determines the target non-terrestrial network cell based on the measurement results of the candidate satellite cells or beams. For example, the source ground base station may select the satellite cell or beam with the best signal quality among the candidate satellite cells or beams as the target non-terrestrial network cell based on the measurement results. For example, the source ground base station may determine the target non-terrestrial network cell based on the identifier of at least one satellite network that the terminal is allowed to access, included in the tenth indication information in step 103; that is, the identifier of the satellite network of the determined target non-terrestrial network cell is included in the identifier of at least one satellite network that the terminal is allowed to access.

[0279] 1013. The source ground base station initiates the process of switching the terminal to the target non-terrestrial network cell based on the fourth or fifth instruction information.

[0280] For example, the source ground base station may determine, based on the identifier of at least one satellite network that the terminal is allowed to access, such as the PLMN ID of the satellite network, included in the tenth indication information in step 103, that the terminal is allowed to switch to the target satellite cell or beam indicated by the fourth indication information. In this case, the source ground base station may initiate a process of switching to the target satellite cell or beam, or the source ground base station may initiate a redirection process to redirect the terminal to the target satellite cell or beam.

[0281] It is understandable that this handover process involves both the terrestrial core network and the satellite core network. It can be referenced from the N2 handover process in 5G. That is, the source terrestrial base station can exchange information through the AMF network element in the terrestrial core network, the AMF network element in the target PLMN, and the target satellite base station corresponding to the target satellite cell or beam to complete the handover to the target satellite cell or beam.

[0282] Therefore, in this application, when the terminal is in a connected state, if the terminal leaves or is about to leave the coverage of the terrestrial network and enters the coverage of a non-terrestrial network, the terminal can obtain auxiliary information from the first network element of the satellite network and determine the target non-terrestrial network cell. When the source terrestrial base station determines, based on the identifier of the satellite network that the terminal is allowed to switch to, as indicated by the terrestrial core network, that the terminal is allowed to switch to the target non-terrestrial network cell, it can initiate a process of switching from the terrestrial cell to the target non-terrestrial network cell or a process of redirection to the target non-terrestrial network cell. Alternatively, the terminal determines a candidate satellite cell or beam and sends the measurement information of the candidate satellite cell or beam to the source base station. The source base station then determines the target non-terrestrial network cell based on the measurement information and the identifier of the satellite network that the terminal is allowed to switch to, as indicated by the terrestrial core network, and initiates a process of switching from the terrestrial cell to the target non-terrestrial network cell or a process of redirection to the target non-terrestrial network cell. In contrast to existing solutions where satellite cells and terrestrial cells belong to different operators and cross-operator configuration of neighbor cell information is not supported, thus preventing handover from terrestrial cells to satellite cells, this application can assist the terminal in measuring satellite cells or beams using auxiliary information provided by the first network element of the satellite network, thereby supporting the terminal's access from a terrestrial cell to a satellite cell.

[0283] Figure 11 illustrates a flowchart of a communication method. This method allows for the handover of satellite cells or beams by the terminal while in a connected state. If the ground core network determines the satellite networks allowed for terminal access and the corresponding first network element, the ground core network can instruct the source ground base station to specify the satellite networks allowed for terminal access and the identifiers of the corresponding first network elements. The source ground base station obtains auxiliary information based on the identifier of the first network element and determines candidate non-terrestrial network cells, then instructs the terminal to measure the candidate non-terrestrial network cells to determine the target non-terrestrial network cell. When the source ground base station determines that the terminal is allowed to hand over to the target non-terrestrial network cell based on the satellite networks allowed for terminal access, it initiates the handover procedure. This method includes the following steps.

[0284] 111. The terminal registers with the ground core network and sends the terminal's capability information to the ground core network.

[0285] For details on how to implement step 111, please refer to the description in step 701.

[0286] 112. The terrestrial core network determines which terminals are allowed to access the network via non-terrestrial networks, and identifies the non-terrestrial networks that support terminal access and the first network element corresponding to the non-terrestrial networks.

[0287] For details on how to implement step 112, please refer to the description in step 702.

[0288] 113. The terrestrial core network sends a tenth indication information to the source terrestrial base station. The tenth indication information includes the identifier of at least one non-terrestrial network that the terminal is allowed to access and the identifier of a first network element. The identifier of the first network element is used by the terrestrial network service equipment of the terminal to obtain auxiliary information from the first network element.

[0289] Accordingly, the source ground base station receives the tenth instruction information sent by the ground core network.

[0290] For example, the tenth indication information includes the identifier of at least one satellite network that the terminal is allowed to access, as well as the identifier of the first network element corresponding to the satellite network. The tenth indication information can also be understood as instructing the source ground base station that the terminal supports switching to a satellite network.

[0291] In some implementations, the tenth indication information may not include the identifier of the first network element. In this implementation, the source terrestrial base station determines the first network element corresponding to each of the at least one non-terrestrial networks based on the identifier of at least one non-terrestrial network that the terminal is allowed to access.

[0292] 114. The source ground base station obtains auxiliary information from the first network element.

[0293] In some embodiments, the source terrestrial base station sends third indication information, which is used to request a first network element to provide auxiliary information. This auxiliary information is used by the terminal to access a non-terrestrial network from a terrestrial network and indicates information about at least one satellite covering the terminal's location. The third indication information includes the terminal's location information. The source terrestrial base station receives first indication information, which includes the auxiliary information.

[0294] The sending of third indication information by the source ground base station includes: the source ground base station sending third indication information to the first network element. The receiving of first indication information by the source ground base station includes: the source ground base station receiving first indication information sent by the first network element.

[0295] The process of the first network element acquiring auxiliary information can be found in the description in step 704.

[0296] If the source ground base station determines, based on the received auxiliary information, that the terminal has moved out of or is about to move out of the coverage area of ​​any one of the satellites in the last received auxiliary information, or determines that the terminal has moved out of or is about to move out of the coverage area of ​​the cell or beam of any one of the satellites in the last received auxiliary information, or determines that the validity period of the cell or beam information of any one of the satellites in the auxiliary information has expired or is about to expire, the source ground base station may request the first network element to update the auxiliary information. The specific implementation method is similar to the process of the ground core network requesting the first network element to update the auxiliary information in steps 707 to 709 above.

[0297] 115. The source ground base station determines at least one candidate non-terrestrial network cell from the non-terrestrial network based on auxiliary information.

[0298] In some embodiments, when determining that a terminal has moved out of or is about to move out of the coverage area of ​​the terrestrial network, the source ground base station determines at least one candidate satellite cell or beam in a satellite network based on auxiliary information.

[0299] For example, the source terrestrial base station can determine whether the terminal has moved out of or is about to move out of the terrestrial network coverage based on the neighboring cell measurement results of the terrestrial cell in which the terminal is serving. For instance, the source terrestrial base station determines that the terminal has moved out of or is about to move out of the terrestrial network coverage when it determines that no neighboring terrestrial cells with signal strength greater than or equal to a strength threshold have been detected.

[0300] Alternatively, the source terrestrial base station can also sense when the terminal is approaching the edge of the terrestrial network coverage, i.e., when the terminal is about to leave the terrestrial network coverage, by combining the configuration of the serving terrestrial cell and the direction of the terminal's movement. For example, if the source terrestrial base station determines that the serving terrestrial cell is deployed at the edge of the terrestrial coverage and the terminal is moving towards the edge, the source terrestrial base station determines that the terminal is about to leave the terrestrial network coverage.

[0301] At this point, the source ground base station can determine candidate satellite cells or beams that the terminal can access based on auxiliary information and the terminal's location information. Specifically, when determining candidate satellite cells or beams, the source ground base station can select satellite cells or beams that can cover the current terminal location, and can select satellite cells or beams with a coverage time greater than or equal to a time threshold. That is, satellite cells or beams with sufficiently long coverage times are selected to reduce the frequency of cell or beam switching by the terminal.

[0302] 116. The source ground base station obtains the measurement configuration information of candidate non-terrestrial network cells.

[0303] In some embodiments, the source ground base station sends a seventh indication information, which is used to request measurement configuration information of candidate non-terrestrial network cells from the first network element; the source ground base station receives an eighth indication information, which includes the measurement configuration information of candidate non-terrestrial network cells obtained by the first network element.

[0304] The implementation method of step 116 can be found in the description of steps 108 to 1010 above.

[0305] 117. The source ground base station sends fourth information, which is used to instruct the terminal to measure the candidate non-terrestrial network cell. The fourth information includes the measurement configuration information of the candidate non-terrestrial network cell.

[0306] In some embodiments, the source ground base station sending the fourth information includes: the source ground base station sending the fourth information to the terminal. Accordingly, the terminal receives the fourth information sent by the source ground base station.

[0307] For example, in some embodiments, the fourth information may also include auxiliary information of candidate non-terrestrial network cells, such as auxiliary information of candidate satellite cells or beams, including the ephemeris of the satellite corresponding to the satellite cell or beam, beam elevation angle, center frequency of the satellite cell or beam, beam scanning period and time slot, etc.

[0308] 118. The terminal measures the candidate non-terrestrial network cells and obtains the measurement results.

[0309] For example, the terminal can measure candidate satellite cells or beams based on the received fourth information. The terminal also aligns its beam direction with the beam direction of the satellite cell or beam for each candidate satellite cell or beam based on the auxiliary information of the candidate satellite cell or beam. After downlink synchronization based on the auxiliary information of the satellite cell or beam, the terminal performs signal measurement of the satellite cell or beam based on the measurement configuration information of the satellite cell or beam to obtain the measurement result of the satellite cell or beam velocity. If the auxiliary information of the non-terrestrial network cell does not include the beam elevation angle, the terminal can calculate the beam elevation angle based on the satellite ephemeris in the auxiliary information of the non-terrestrial network cell and perform beam alignment. In some embodiments, the auxiliary information of the candidate satellite cell or beam is included in the fourth information. In other embodiments, the ground base station can send the auxiliary information to the terminal before step 115; that is, the ground base station obtains the terminal's auxiliary information from the first network element and sends it to the terminal. After receiving the fourth information, the terminal determines the beam direction and performs downlink synchronization based on the auxiliary information and the identifiers of candidate satellite cells or beams and the corresponding satellite identifiers included in the fourth information, and performs measurements on the candidate satellite cells or beams based on the measurement configuration information in the fourth information.

[0310] 119. The terminal sends a fifth indication information to the source ground base station. The fifth indication information includes the measurement results of at least one candidate non-terrestrial network cell in the non-terrestrial network. The measurement results are used to determine the target non-terrestrial network cell.

[0311] The implementation method of step 119 can be found in the description of step 1012 above.

[0312] 120. The source ground base station initiates the process of switching the terminal to the target non-terrestrial network cell according to the fifth instruction information.

[0313] The implementation method of step 120 can be found in the description of step 1013 above.

[0314] In this application, steps 114 and 116 can also be performed by the terrestrial core network, i.e., the terrestrial core network obtains auxiliary information and measurement configuration information of candidate non-terrestrial network cells. In this case, step 114 can be performed before step 113, i.e., the terrestrial core network first obtains auxiliary information and includes auxiliary information in the tenth indication information. If the source terrestrial base station determines that the terminal has moved out of or is about to move out of the terrestrial network coverage, the source terrestrial base station can first notify the terrestrial core network, and the terrestrial core network obtains updated auxiliary information from the first network element and sends it to the source terrestrial base station. If step 116 is performed by the terrestrial core network, when the source terrestrial base station obtains candidate non-terrestrial network cells in step 115, the source terrestrial base station can send indication information of candidate non-terrestrial network cells to the terrestrial core network, and the terrestrial core network performs step 116, i.e., obtains measurement configuration information of non-terrestrial network cells from the first network element. After the terrestrial core network sends the measurement configuration information to the source terrestrial base station, the source terrestrial base station continues to perform step 117.

[0315] Therefore, in this application, when the terminal is in a connected state, if the terminal leaves or is about to leave the coverage of the terrestrial network and enters the coverage of a non-terrestrial network, the source terrestrial base station can obtain auxiliary information from the first network element of the satellite network and determine candidate non-terrestrial network cells. The source terrestrial base station instructs the terminal to measure the candidate non-terrestrial network cells, obtain the measurement results, and then initiates the process of handing over from the terrestrial cell to the target non-terrestrial network cell. In this way, compared with the existing scheme, if the satellite cell and the terrestrial cell belong to different operators, cross-operator support for configuring neighbor cell information will prevent handover from the terrestrial cell to the satellite cell. This application can assist the terminal in measuring the satellite cell or beam through the auxiliary information provided by the first network element of the satellite network, so as to support the terminal to access the satellite cell from the terrestrial cell.

[0316] It is understood that, in order to achieve the functions in the above embodiments, the network devices and terminals include hardware structures and / or software modules corresponding to perform each function. Those skilled in the art should readily recognize that, based on the units and method steps described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0317] Figures 12 and 13 are schematic diagrams of possible communication devices provided in embodiments of this application. These communication devices can be used to implement the functions of the terminal, the first network element, the core network equipment of the terrestrial network, or the service network equipment of the terrestrial network in the above method embodiments, and thus can also achieve the beneficial effects of the above method embodiments. In the embodiments of this application, the communication device can be the terminal 1005 shown in Figure 1, the topology service shown in Figure 1, the core network equipment in the terrestrial core network 1002 shown in Figure 1, the terrestrial base station shown in Figure 1, or a module (such as a chip) applied to the terminal, the topology service, the core network equipment of the terrestrial core network, or the terrestrial base station.

[0318] As shown in Figure 12, the communication device 1200 includes a processing unit 1210 and a transceiver unit 1220. The communication device 1200 is used to implement the functions of the terminal or network device in the method embodiments shown in Figures 3 to 7, Figure 10 and Figure 11.

[0319] When the communication device 1200 is used to implement the functions of the terminal in the method embodiment shown in FIG3: the transceiver unit 1220 is used to receive first indication information, indicating auxiliary information; the processing unit 1210 is used to access at least one target non-terrestrial network cell in a non-terrestrial network based on the auxiliary information.

[0320] When the communication device 1200 is used to implement the functions of the terminal in the method embodiment shown in FIG7: the transceiver unit 1220 is used to send capability information; receive first indication information, including auxiliary information; receive third information, including updated auxiliary information; receive second indication information, including the identifier of the first network element; send third indication information to request the first network element to provide auxiliary information; and the processing unit 1210 is used to search for non-terrestrial network cells based on the auxiliary information.

[0321] When the communication device 1200 is used to implement the functions of the terminal in the method embodiment shown in FIG10: the transceiver unit 1220 is used to send capability information; receive second indication information, including the identifier of the first network element; send third indication information, requesting the first network element to provide auxiliary information; receive first indication information, including auxiliary information; receive sixth indication information, indicating that the terminal has moved out of or is about to move out of the coverage of the terrestrial network, or indicating that the terminal performs measurements on the non-terrestrial network; send seventh indication information, requesting the first network element to provide measurement configuration information of candidate non-terrestrial network cells; receive eighth indication information, including measurement configuration information of candidate non-terrestrial network cells; send fourth or fifth indication information; and the processing unit 1210 is used to perform measurements on the candidate non-terrestrial network cells.

[0322] When the communication device 1200 is used to implement the functions of the terminal in the method embodiment shown in FIG11: the transceiver unit 1220 is used to send capability information; receive fourth information to instruct the terminal to measure the candidate non-terrestrial network cell; send fourth indication information or fifth indication information; and the processing unit 1210 is used to measure the candidate non-terrestrial network cell.

[0323] When the communication device 1200 is used to implement the functions of the network equipment of the terrestrial core network in the method embodiment shown in FIG4: the processing unit 1210 is used to obtain the identifier of the first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access. The transceiver unit 1220 is used to send first indication information, indicating auxiliary information; or, send second indication information, including the identifier of the first network element; or, send ninth indication information, including the identifier of at least one non-terrestrial network that the terminal is allowed to access and the identifier of the first network element.

[0324] When the communication device 1200 is used to implement the functions of the network equipment of the terrestrial core network in the method embodiment shown in FIG7: the processing unit 1210 is used to determine that the terminal is allowed to access through a non-terrestrial network, and to determine the non-terrestrial network that the terminal is allowed to access and the first network element corresponding to the non-terrestrial network; record the coverage information of the satellite cell or beam and the validity period in the auxiliary information; determine that the terminal has moved out of or is about to move out of the satellite's coverage area or that the validity period has expired or is about to expire; the transceiver unit 1220 is used to send a third indication information to request the first network element to provide auxiliary information; receive the first indication information, including auxiliary information; send the first indication information; send the first information to request the first network element to update the auxiliary information; receive the second information to indicate the updated auxiliary information; send the third information to indicate the updated auxiliary information to the terminal.

[0325] When the communication device 1200 is used to implement the function of the network equipment of the terrestrial core network in the method embodiment shown in FIG10: the processing unit 1210 is used to determine that the terminal is allowed to access through a non-terrestrial network, and to determine the non-terrestrial network that the terminal is allowed to access and the first network element corresponding to the non-terrestrial network; the transceiver unit 1220 is used to send a tenth indication information to the source terrestrial base station, indicating that the terminal is allowed to switch from the terrestrial network to the satellite network, including the identifier of at least one satellite network.

[0326] When the communication device 1200 is used to implement the function of the network equipment of the terrestrial core network in the method embodiment shown in FIG11: the processing unit 1210 is used to determine that the terminal is allowed to access through the non-terrestrial network, and to determine the non-terrestrial network that the terminal is allowed to access and the first network element corresponding to the non-terrestrial network; and to determine at least one candidate non-terrestrial network cell in the non-terrestrial network according to the auxiliary information.

[0327] When the communication device 1200 is used to implement the function of the first network element of the non-terrestrial network in the method embodiment shown in FIG5: the transceiver unit 1220 is used to receive the third instruction information and request auxiliary information; and send the first instruction information, including auxiliary information.

[0328] When the communication device 1200 is used to implement the function of the first network element of the non-terrestrial network in the method embodiment shown in FIG7, FIG10 or FIG11: the transceiver unit 1220 is used to receive third indication information and request the first network element to provide auxiliary information; send first indication information, including auxiliary information; receive first information and request to update the auxiliary information; send second information to indicate the updated auxiliary information; send eighth indication information, including measurement configuration information of candidate non-terrestrial network cells; the processing unit 1210 is also used to obtain measurement configuration information of at least one candidate terrestrial cell.

[0329] When the communication device 1200 is used to implement the function of the service network device of the terrestrial network in the method embodiment shown in FIG6: the transceiver unit 1220 is used to receive the tenth indication information, indicating that the terminal is allowed to switch from the terrestrial network to the satellite network, including the identifier of at least one satellite network; receive the fourth indication information or the fifth indication information; the processing unit 1210 is used to initiate the process of the terminal switching to the target non-terrestrial network cell according to the fourth indication information or the fifth indication information.

[0330] When the communication device 1200 is used to implement the function of the service network device (source satellite base station) of the terrestrial network in the method embodiment shown in FIG7: the transceiver unit 1220 is used to receive the ninth indication information, including the identifier of at least one non-terrestrial network that the terminal is allowed to access and the identifier of the first network element; send the third indication information to request auxiliary information; receive the first indication information, including auxiliary information; and send the first indication information.

[0331] When the communication device 1200 is used to implement the function of the service network device (source satellite base station) of the non-terrestrial network in the method embodiment shown in FIG10: the transceiver unit 1220 is used to receive the tenth instruction information; send the sixth instruction information to the terminal; receive the fourth instruction information or the fifth instruction information; the processing unit 1210 is used to initiate the process of switching the terminal to the target non-terrestrial network cell based on the fourth instruction information or the fifth instruction information.

[0332] When the communication device 1200 is used to implement the function of the service network device (source satellite base station) of the non-terrestrial network in the method embodiment shown in FIG10: the processing unit 1210 is used to obtain auxiliary information from the first network element; obtain the measurement configuration information of the candidate non-terrestrial network cell; and initiate the process of switching the terminal to the target non-terrestrial network cell based on the fourth indication information or the fifth indication information. The transceiver unit 1220 is used to send the fourth information, including the auxiliary information of the non-terrestrial network cell and the measurement configuration information; and receive the fourth information or the fifth indication information.

[0333] For a more detailed description of the processing unit 1210 and the transceiver unit 1220, please refer to the relevant descriptions in the method embodiments shown in Figures 3 to 7, Figure 10 and Figure 11.

[0334] As shown in Figure 13, the communication device 1300 includes a processor 1310 and an interface circuit 1320. The processor 1310 and the interface circuit 1320 are coupled to each other. It is understood that the interface circuit 1320 can be a transceiver or an input / output interface. Optionally, the communication device 1300 may also include a memory 1330 for storing instructions executed by the processor 1310, or storing input data required by the processor 1310 to execute instructions, or storing data generated after the processor 1310 executes instructions.

[0335] When the communication device 1300 is used to implement the methods shown in Figures 3 to 7, Figure 10 and Figure 11, the processor 1310 is used to implement the functions of the processing unit 1210, and the interface circuit 1320 is used to implement the functions of the transceiver unit 1220.

[0336] When the aforementioned communication device is a chip applied to a terminal, the terminal chip implements the functions of the terminal in the above method embodiments. The terminal chip receives information from the base station, which can be understood as the information being first received by other modules in the terminal (such as an RF module or antenna), and then sent to the terminal chip by these modules. The terminal chip sends information to the base station, which can be understood as the information being first sent to other modules in the terminal (such as an RF module or antenna), and then sent to the base station by these modules.

[0337] When the aforementioned communication device is a chip applied to network equipment (core network equipment or access network equipment), the network equipment chip implements the functions of the network equipment in the above method embodiments. The network equipment chip receiving information from the terminal can be understood as the information being first received by other modules (such as radio frequency modules or antennas) in the network equipment, and then sent to the network equipment chip by these modules. The network equipment chip sending information to the terminal can be understood as the information being forwarded to other modules (such as radio frequency modules or antennas) in the network equipment, and then sent to the terminal by these modules.

[0338] In this application, entity A sends information to entity B, either directly or indirectly through other entities. Similarly, entity B receives information from entity A, either directly or indirectly through other entities. Entities A and B can be RAN nodes or terminals, or modules within RAN nodes or terminals. Information transmission and reception can be between RAN nodes and terminals, such as between a base station and a terminal; between two RAN nodes, such as between a CU and a DU; or between different modules within a single device, such as between a terminal chip and other modules of the terminal, or between a base station chip and other modules of the base station.

[0339] It is understood that the processor in the embodiments of this application can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0340] The method steps in the embodiments of this application can be implemented in hardware or in software instructions executable by a processor. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. The storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Alternatively, the ASIC can reside in a base station or terminal. The processor and storage medium can also exist as discrete components in a base station or terminal.

[0341] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are performed entirely or partially. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user equipment, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both types of storage media.

[0342] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0343] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship. "Including at least one of A, B, and C" can mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B, and C.

[0344] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

Claims

1. A communication method, characterized in that, include: Receive first indication information, the first indication information including auxiliary information, the auxiliary information being used by the terminal to access a non-terrestrial network from a terrestrial network, the auxiliary information being provided by a first network element corresponding to at least one non-terrestrial network that allows the terminal to access; Access to a target non-terrestrial network cell in at least one non-terrestrial network based on the auxiliary information, wherein the target non-terrestrial network cell includes cells within the satellite coverage area; The auxiliary information is used to indicate information about at least one satellite covering the terminal location. The information of any one of the at least one satellites includes at least one of the following: the satellite's identifier, the satellite's ephemeris information, time information, the satellite's coverage information, or information about at least one cell or beam of the satellite. The information about the satellite's cell or beam includes at least one of the following: the identifier of the satellite's cell or beam, the frequency information of the satellite's cell or beam, the scanning period of the satellite's cell or beam, the scanning time slot of the satellite's cell or beam, the coverage information of the satellite's cell or beam, or the validity period of the information about the satellite's cell or beam.

2. The method according to claim 1, characterized in that, Before receiving the first indication information, the method further includes: Send capability information, the capability information indicating that the terminal has at least one of the following capabilities: The terminal supports access via a non-terrestrial network cell, the terminal supports switching from the terrestrial cell to a non-terrestrial network cell for access, or the terminal supports redirection from the terrestrial cell to a non-terrestrial network cell for access.

3. The method according to claim 1 or 2, characterized in that, Before receiving the first indication information, the method further includes: Receive second indication information, the second indication information including the identifier of the first network element; Send a third instruction message, which is used to request the first network element to provide the auxiliary information, and the third instruction message includes the location information of the terminal.

4. The method according to any one of claims 1-3, characterized in that, The target non-terrestrial network cell in the at least one non-terrestrial network accessed based on the auxiliary information includes: Based on the auxiliary information, the cell or beam of the candidate satellite among the at least one satellite is determined, and downlink synchronization is performed with the cell or beam of the candidate satellite; The cell or beam of the candidate satellite is measured to obtain the measurement results; The target non-terrestrial network cell is determined from the cells or beams of the candidate satellites based on the measurement results.

5. The method according to claim 4, characterized in that, The target non-terrestrial network cell accessing the at least one non-terrestrial network includes: The terminal resides in the target non-terrestrial network cell; Alternatively, the terminal may receive and / or transmit signaling and / or data through the target non-terrestrial network cell; Alternatively, a fourth instruction message may be sent, the fourth instruction message including the identifier of the target non-terrestrial network cell, the fourth instruction message being used to instruct the terminal to initiate a process of switching the terminal to the target non-terrestrial network cell in the terrestrial network serving network device.

6. The method according to any one of claims 1-3, characterized in that, The step of accessing the target non-terrestrial network surface cell in the at least one non-terrestrial network according to the auxiliary information includes: The at least one candidate non-terrestrial network cell is determined from the cells or beams of the satellite indicated by the auxiliary information based on the location of the terminal; The candidate non-terrestrial network cells are measured to obtain the measurement results; Send a fifth instruction message, the fifth instruction message including the measurement result, the measurement result being used by the terrestrial network serving network equipment to determine the target non-terrestrial network cell, and initiate a process to switch the terminal to the target non-terrestrial network cell.

7. The method according to claim 6, characterized in that, Before determining the candidate non-terrestrial network cells, the method further includes: The terminal receives a sixth indication message, which is used to indicate that it has moved out of or is about to move out of the coverage area of ​​the terrestrial network, or the sixth indication message is used to indicate that the terminal performs measurements on a non-terrestrial network.

8. The method according to claim 6 or 7, characterized in that, Before sending the fifth indication information, the method further includes: Send a seventh indication message, the seventh indication message being used to request the measurement configuration information of the candidate non-terrestrial network cell from the first network element; Receive the eighth indication information, which includes the measurement configuration information of the candidate non-terrestrial network cell.

9. A communication method, characterized in that, include: Obtain the identifier of the first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access; Send a first indication message, the first indication message being used to indicate auxiliary information to the terminal; Alternatively, a second instruction message may be sent, the second instruction message including the identifier of the first network element, the identifier of the first network element being used by the terminal to obtain auxiliary information from the first network element; Alternatively, a ninth indication message may be sent, the ninth indication message including an identifier of at least one non-terrestrial network that the terminal is allowed to access and an identifier of the first network element, the identifier of the first network element being used by the terminal's terrestrial network service network device to obtain auxiliary information from the first network element. The auxiliary information is used by the terminal to access a non-terrestrial network from a terrestrial network, and the auxiliary information is used to indicate information about at least one satellite covering the location of the terminal. The information about the at least one satellite includes at least one of the following: the satellite's identifier, the satellite's ephemeris information, time information, the satellite's coverage information, and information about at least one cell or beam of the satellite. The information about the cell or beam of the satellite includes at least one of the following: the cell or beam's identifier, the cell or beam's frequency information, the cell or beam's scanning period, the cell or beam's scanning time slot, the cell or beam's coverage information, or the effective time of the cell or beam's information.

10. The method according to claim 9, characterized in that, When sending the second indication information, the method further includes: in addition to sending the second indication information, Send a tenth instruction message, which is used to instruct the terminal to switch from the terrestrial network to a non-terrestrial network to the service network equipment of the terrestrial network. The tenth instruction message includes an identifier of at least one non-terrestrial network that the terminal is allowed to access.

11. The method according to claim 9 or 10, characterized in that, Before obtaining the identifier of the first network element corresponding to at least one non-terrestrial network that the terminal is allowed to access, the method further includes: Receive capability information, the capability information indicating that the terminal has at least one of the following capabilities: The terminal indicates access via a non-terrestrial network cell, the terminal supports switching from a terrestrial cell to a non-terrestrial network cell for access, or the terminal supports redirection from a terrestrial cell to a non-terrestrial network cell for access.

12. The method according to any one of claims 9-11, characterized in that, The at least one non-terrestrial network and the first network element corresponding to the at least one non-terrestrial network are determined based on the terminal's location information, subscription information, and roaming agreements between the terrestrial network operator and the non-terrestrial network operator.

13. The method according to any one of claims 9-12, characterized in that, Before sending the first indication information, the method further includes: Send a third instruction message, the third instruction message being used to request the first network element to provide the auxiliary information, the third instruction message including the location information of the terminal; The first instruction information is received, and the first instruction information includes the auxiliary information.

14. The method according to any one of claims 9-13, characterized in that, The method further includes: When the terminal moves out of or is about to move out of the coverage area of ​​any of the at least one satellite, or when the terminal moves out of or is about to move out of the coverage area of ​​the cell or beam of any of the at least one satellite, or when the validity period of the cell or beam information of any of the at least one satellite expires or is about to expire, a first message is sent. The first message is used to request the first network element to update the auxiliary information. The first message includes the current location information of the terminal. Receive a second message, which indicates the updated auxiliary information; A third message is sent, which is used to indicate the updated auxiliary information to the terminal.

15. A communication method, characterized in that, include: Receive a third indication information, the third indication information being used to request auxiliary information, the auxiliary information being used by the terminal to access a non-terrestrial network from a terrestrial network, the third indication information including the location information of the terminal; Send a first instruction message, the first instruction message including the auxiliary information; The auxiliary information is used to indicate information about at least one satellite covering the terminal location. The information about the at least one satellite includes at least one of the following: the satellite's identifier, the satellite's ephemeris information, time information, the satellite's coverage information, and information about at least one cell or beam of the satellite. The information about the cell or beam of the satellite includes at least one of the following: the cell or beam's identifier, the cell or beam's frequency information, the cell or beam's scanning period, the cell or beam's scanning time slot, the cell or beam's coverage information, or the effective time of the cell or beam's information.

16. The method according to claim 15, characterized in that, The auxiliary information is determined based on the terminal's location information, the satellite constellation information of the satellite network, the configuration information of each satellite in the satellite network, and the current time information.

17. The method according to claim 15 or 16, characterized in that, The method further includes: Send a second message, which indicates the updated auxiliary information.

18. The method according to claim 17, characterized in that, Before sending the second information, the method further includes: The terminal receives first information, which is used to indicate that it has moved out of or is about to move out of the coverage area of ​​any of the at least one satellite, or when the terminal moves out of or is about to move out of the coverage area of ​​the cell or beam of any of the at least one satellite, or when the validity period of the cell or beam information of any of the at least one satellite expires or is about to expire, and requests to update the auxiliary information, wherein the first information includes the current location information of the terminal.

19. A communication method, characterized in that, include: Receive tenth indication information, the tenth indication information being used to indicate that the terminal is allowed to switch from a terrestrial network to a non-terrestrial network, the tenth indication information including an identifier of at least one non-terrestrial network that the terminal is allowed to access; Receive a fourth indication information or a fifth indication information, wherein the fourth indication information includes the identifier of the target non-terrestrial network cell in the at least one non-terrestrial network, and the fifth indication information includes the measurement results of the candidate non-terrestrial network cells in the at least one non-terrestrial network, and the measurement results are used to determine the target non-terrestrial network cell; The process of switching the terminal to the target non-terrestrial network cell is initiated based on the fourth or fifth instruction information.

20. The method according to claim 19, characterized in that, The tenth indication information also includes the identifier of the first network element corresponding to the at least one non-terrestrial network; Before receiving the fourth or fifth indication information, the method further includes: Send a third indication message, the third indication message being used to request the first network element to provide auxiliary information, the auxiliary information being used for the terminal to access a non-terrestrial network from a terrestrial network, and being used to indicate information about at least one satellite covering the location of the terminal, the third indication message including the location information of the terminal; Receive first instruction information, the first instruction information including the auxiliary information; Based on the auxiliary information, determine the candidate non-terrestrial network cells in the at least one non-terrestrial network; Send a fourth message, which instructs the terminal to measure the candidate non-terrestrial network cell, the fourth message including auxiliary information of the candidate non-terrestrial network cell.

21. The method according to claim 19, characterized in that, Before receiving the fourth or fifth indication information, the method further includes: Send a sixth indication message, which is used to indicate that the terminal has moved out of or is about to move out of the coverage area of ​​the terrestrial network, or the sixth indication message is used to indicate that the terminal performs measurements on a non-terrestrial network.

22. The method according to claim 20 or 21, characterized in that, Before sending the fourth information or the sixth indication information, the method further includes: Determine whether the terminal has moved out of or is about to move out of the coverage area of ​​the terrestrial network.

23. The method according to claim 20, characterized in that, The fourth information also includes the measurement configuration information of the candidate non-terrestrial network cells; Before sending the fourth information, the method further includes: Send a seventh indication message, the seventh indication message being used to request the measurement configuration information of the candidate non-terrestrial network cell from the first network element; The eighth indication information is received, which includes the measurement configuration information of the candidate non-terrestrial network cell obtained by the first network element.

24. A communication device, characterized in that, The communication device includes a module for performing the method as described in any one of claims 1-8, or a module for performing the method as described in any one of claims 9-14, or a module for performing the method as described in any one of claims 15-18, or a module for performing the method as described in any one of claims 19-23.

25. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed on a communication device, cause the communication device to perform the method as described in any one of claims 1-8, or the method as described in any one of claims 9-14, or the method as described in any one of claims 15-18, or the method as described in any one of claims 19-23.

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