Satellite handover method, communication system, terminal device, satellite and related apparatus

Abstract

This application provides a satellite handover method, communication system, terminal device, satellite, and related apparatus, relating to the field of communication technology. The method includes a source satellite broadcasting a first signal. The terminal device receives the first signal from the source satellite. The first signal includes beam range information of the source satellite and target satellite information. The terminal device sends a first scheduling request (SR) to the target satellite. The SR is used for satellite handover. The first compensation parameter for time-frequency pre-compensation used in the first SR is determined based on the first location of the terminal device and the target satellite information. The first location is related to the beam range information, altitude, and synchronization parameters of the source satellite, but is independent of GNSS positioning and the target satellite's SSB. This method can improve the success rate of satellite handover for the terminal device in hard handover scenarios or in scenarios where the terminal device cannot perform GNSS positioning (such as GNSS-inaccessible scenarios).

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a satellite switching method, communication system, terminal equipment, satellite and related devices. Background Technology

[0002] With the rapid development of satellite internet, non-terrestrial network (NTN) systems deploy numerous satellites to provide continuous communication services to remote areas, oceans, polar regions, and other regions where terrestrial base stations struggle to cover. In NTN systems, user equipment (UE) must frequently switch between high-speed moving satellites to maintain connectivity.

[0003] In some implementations, the UE uses a handover method based on synchronization signal block (SSB) measurements to switch from the source satellite to the target satellite. Alternatively, the UE uses a GNSS positioning-assisted handover method to switch from the source satellite to the target satellite. The SSB-based handover method requires the UE to measure the SSBs of both the source and target satellites, and is suitable for scenarios where the source and target satellite beams overlap.

[0004] If the UE cannot measure the SSB of the source satellite and the target satellite, and the UE cannot perform GNSS positioning, the success rate of the UE in satellite handover is low, and it may even prevent the user from using the UE for satellite communication. Summary of the Invention

[0005] This application provides a satellite handover method, communication system, terminal equipment, satellite, and related devices, applicable to the field of communication technology. It can improve the success rate of satellite handover.

[0006] In a first aspect, embodiments of this application propose a satellite handover method applied to a terminal device. The method includes: receiving a first signal from a source satellite, the first signal including beam range information of the source satellite and target satellite information; sending a first scheduling request (SR) to the target satellite, the SR being used for satellite handover; and a first compensation parameter for time-frequency pre-compensation of the first SR being determined based on a first position of the terminal device and the target satellite information. The first position is output by a first model after inputting the beam range information, the altitude of the source satellite, and the latest received synchronization parameters from the source satellite into the first model. The first model is constructed from equal-delay circles, equal-Doppler lines, and beam range circles. The first model being constructed from equal-delay circles, equal-Doppler lines, and beam range circles can be understood as being modeled based on equal-delay circles, equal-Doppler lines, and beam range circles.

[0007] Thus, the first signal includes the beam range information of the source satellite and the target satellite information, so that the terminal device can use the beam range information of the source satellite to determine the location of the terminal device. The first signal includes the target satellite information, so that the terminal device can use the location of the terminal device and the target satellite information to determine the first compensation parameter. The first position is output by the first model when the beam range information of the source satellite, the altitude of the source satellite, and the latest synchronization parameters received by the terminal device (i.e., UE) from the source satellite are input into the first model. The determination of the first position is independent of GNSS positioning and also independent of the SSB of the target satellite. That is, the determination of the first position does not depend on GNSS positioning or the SSB of the target satellite. Regardless of whether the terminal device can measure the SSB of the source satellite and the target satellite, and regardless of whether the terminal device can perform GNSS positioning, the terminal device can use the satellite handover method provided in this application embodiment to perform satellite handover. The satellite handover method provided in this application embodiment can reduce the probability of a reduced satellite handover success rate due to the terminal device's inability to simultaneously measure the SSB of the source satellite and the target satellite and the terminal device's inability to perform GNSS positioning. In SSB scenarios where the terminal device cannot measure the source and target satellites (e.g., hard handover scenarios) or in scenarios where the terminal device cannot perform GNSS positioning (e.g., GNSS stoppage scenarios), the success rate of satellite handover for the terminal device can be improved. The first position is determined by a first model constructed from equal-delay circles, equal-Doppler lines, and beam range circles, based on the source satellite's beam range information, altitude, and the latest received synchronization parameters from the source satellite. This allows for the geometric constraint determination of the terminal device's first position using equal-delay circles, equal-Doppler lines, and beam range circles on the beam range information, source satellite altitude, and the latest received synchronization parameters from the source satellite. This improves the accuracy of the terminal device's position determination, thereby improving the accuracy of the first compensation parameters based on the terminal device's position determination. This, in turn, increases the success rate of the target satellite receiving the first SR, thus improving the success rate of the terminal device accessing the target satellite and ultimately enhancing the satellite handover success rate.

[0008] In one possible implementation, the method further includes: starting a first timer. Before the first timer expires, receiving a response from the target satellite, the response indicating a successful satellite handover.

[0009] In this way, the response is used to indicate that the satellite handover was successful. Receiving a response from the target satellite before the first timer expires indicates that the terminal device has successfully completed the satellite handover, and the terminal device can then communicate via the NTN network where the target satellite resides.

[0010] In one possible implementation, the method further includes: starting a first timer. If the first timer times out and no response is received from the target satellite, the process falls back to the Physical Random Access Channel (PRACH) random access procedure.

[0011] Thus, if the first timer times out and no response is received from the target satellite, it could indicate a satellite handover failure or a RACH-less handover failure. The terminal device can then fall back to the PRACH random access procedure to perform PRACH random access. This allows the terminal device to access the target satellite through the PRACH random access procedure and achieve satellite handover.

[0012] In one possible implementation, the method further includes: starting a first timer. If the first timer times out and no response is received from the target satellite, a second SR is sent to the target satellite. The second compensation parameter for the time-frequency pre-compensation of the second SR is determined based on the second position of the terminal device and the target satellite information. The second position is output by the first model when the beam range information, the altitude of the source satellite, and the synchronization parameters are input into the first model.

[0013] Thus, given the first and second positions output by the first model, the terminal device's position could be either the first or the second position. Therefore, RACH-less handover can be performed sequentially using the first compensation parameter corresponding to the first position and the second compensation parameter corresponding to the second position. If the first timer times out and no response is received from the target satellite, it indicates that the RACH-less handover based on the first compensation parameter has failed. In the event of a failed RACH-less handover based on the first compensation parameter, the terminal device can apply the second compensation parameter and send a second SR to the target satellite to perform the RACH-less handover again. By enabling RACH-less handover to be performed sequentially using possible positions or by performing sequential RACH-less detection when the terminal device's position is ambiguous, the success rate of satellite handover can be improved, facilitating rapid access to the target satellite by the terminal device.

[0014] In one possible implementation, the method further includes: starting a second timer. Before the second timer expires, a response is received from the target satellite, indicating that the satellite handover was successful.

[0015] In this way, the response is used to indicate that the satellite handover was successful. Receiving a response from the target satellite before the second timer expires can indicate that the terminal device has successfully performed a satellite handover or that the terminal device has successfully performed a sequential RACH-less detection, allowing the terminal device to communicate via the NTN network where the target satellite resides.

[0016] In one possible implementation, the method further includes: starting a second timer. If the second timer times out and no response is received from the target satellite, the process falls back to the PRACH random access procedure.

[0017] Thus, if the second timer times out and no response is received from the target satellite, it could indicate a satellite handover failure, a RACH-less handover failure, or a failure of the sequential RACH-less probe. The terminal device can then fall back to the PRACH random access procedure to perform PRACH random access. This allows the terminal device to access the target satellite through the PRACH random access procedure and achieve satellite handover.

[0018] In one possible implementation, the source satellite's beam range information includes the source satellite's beam radius, and the synchronization parameters include a first time advance (TA) and a first frequency offset (FO). The first position is the intersection of a first equal-delay circle and a first equal-Doppler line, and this first position lies within the first beam range circle. The first equal-delay circle is determined based on the first TA and the source satellite's altitude. The first equal-Doppler line is determined based on the first FO, the source satellite's flight direction, and the source satellite's flight velocity. The radius of the first beam range circle is the source satellite's beam radius.

[0019] Thus, the first position is the intersection of the first equal-delay circle and the first equal-Doppler line, which allows the terminal equipment position to be determined by the constraints of the first equal-delay circle and the first equal-Doppler line. The first position is located within the first beam range circle, which allows for further constraints on the determined terminal equipment position to determine the first position. The first equal-delay circle is related to the first TA and the altitude of the source satellite. The first equal-Doppler line is related to the first FO, the flight direction of the source satellite, and the flight speed of the source satellite. The radius of the first beam range circle is the beam radius, which allows the determination of the first position based on the synchronization parameters and beam range information of the source satellite. This enables the determination of the first position of the terminal equipment without measuring the SSB of the target satellite or GNSS positioning.

[0020] In one possible implementation, the source satellite's beam range information also includes the source satellite's beam center position. In a coordinate system with the center of the first equal-delay circle as the origin and the source satellite's flight direction as the positive X-axis, the source satellite's beam center position is: The coordinates of the first position are (x1, y1, 0), and the first coordinates satisfy the formula:

[0021]

[0022] in, Let be the radius of the first equal-time-delay circle. , For the first TA, As a preset value, This indicates the common delay compensation of the source satellite. The altitude of the source satellite, , c is the speed of light. , The carrier frequency of the source satellite. This indicates the common frequency compensation of the source satellite. For the first FO, The velocity or flight speed of the source satellite. Where is the beam radius of the source satellite. Optionally, It can be a preset value. It can be a preset value.

[0023] Thus, the first coordinate satisfies This allows the obtained first coordinates to lie on the first equal-delay circle, thus implementing constraint 1 based on the first equal-delay circle to limit the UE position. The first coordinates satisfy... This allows the obtained first coordinates to lie on the first iso-Doppler line, thus further defining the UE position based on constraint 2 of the first iso-Doppler line. The first coordinates satisfy... This allows the obtained first coordinates to be located within the first beam range circle, thereby further defining the UE position based on the constraint 3 of the first beam range circle, thus determining the first coordinates, i.e., determining the first position.

[0024] In one possible implementation, the target satellite information includes the target satellite's position information and its flight speed. and the carrier frequency of the target satellite The first compensation parameter includes the first time delay compensation. and the first frequency pre-compensation value .

[0025] Satisfying the formula:

[0026]

[0027] Satisfying the formula:

[0028]

[0029] Satisfying the formula:

[0030]

[0031] in, Indicates the distance between the first position and the target satellite. At the speed of light, The flight speed of the target satellite Decomposition amount in the X-axis direction, The flight speed of the target satellite The decomposition amount in the Y-axis direction. This represents the position of the target satellite along the X-axis. This represents the position of the target satellite along the Y-axis. The value of the target satellite's position in the Z-axis direction or the target satellite's altitude, the target satellite's position ( , , The location is determined based on the target satellite's position information.

[0032] In this way, the position based on the target satellite can be achieved ( , , ), the flight speed of the target satellite The first compensation parameter is determined based on the carrier frequency of the target satellite, the first position determined based on the synchronization parameters and beam range information of the source satellite, and the source satellite. and This allows the terminal equipment to use the first compensation parameter for satellite switching.

[0033] In one possible implementation, the source satellite's beam range information includes the source satellite's beam radius, and the synchronization parameters include a first time advance (TA) and a first frequency offset (FO). The second position is the intersection of a first equal-delay circle and a first equal-Doppler line, and the second position is located within the first beam range circle. The first equal-delay circle is determined based on the first TA and the source satellite's altitude; the first equal-Doppler line is determined based on the first FO, the source satellite's flight direction, and velocity; and the radius of the first beam range circle is the beam radius.

[0034] Thus, the second position is the intersection of the first equal-delay circle and the first equal-Doppler line, which allows the terminal equipment position to be determined by the constraints of the first equal-delay circle and the first equal-Doppler line. The second position is located within the first beam range circle, which allows for further constraints on the determined terminal equipment position to determine the second position. The first equal-delay circle is related to the first TA and the altitude of the source satellite. The first equal-Doppler line is related to the first FO. The radius of the first beam range circle is the beam radius, which allows the second position to be determined based on the synchronization parameters and beam range information of the source satellite. This enables the determination of the second position of the terminal equipment without measuring the target satellite's SSB or using GNSS positioning.

[0035] In one possible implementation, the source satellite's beam range information also includes the source satellite's beam center position. In a coordinate system with the center of the first equal-delay circle as the origin and the source satellite's flight direction as the positive X-axis, the source satellite's beam center position is: The coordinates of the second position are (x2, y2, 0), and the second coordinates satisfy the formula:

[0036]

[0037] in, Let be the radius of the first equal-time-delay circle. , For the first TA, This indicates the common delay compensation of the source satellite. where c is the altitude of the source satellite and c is the speed of light. , , , The carrier frequency of the source satellite. This indicates the common frequency compensation of the source satellite. For the first FO, The velocity or flight speed of the source satellite. The beam radius of the source satellite.

[0038] Thus, the second coordinate satisfies This allows the obtained second coordinates to lie on the first equal-delay circle, thus achieving constraint 1, which limits the UE position based on the first equal-delay circle. The second coordinates satisfy... This allows the obtained second coordinates to lie on the first iso-Doppler line, thus further defining the UE position based on constraint 2 of the first iso-Doppler line. The second coordinates satisfy... This allows the obtained second coordinates to lie within the first beam range circle, further defining the UE position based on constraint 3 of the first beam range circle. Thus, the second coordinates are determined, and the second position is determined.

[0039] In one possible implementation, the target satellite information includes the target satellite's position information and its flight speed. and the carrier frequency of the target satellite The second compensation parameter includes a second time delay compensation. Second frequency pre-compensation value .

[0040] Satisfying the formula:

[0041]

[0042] Satisfying the formula:

[0043]

[0044] Satisfying the formula:

[0045]

[0046] in, Indicates the distance between the second position and the target satellite. At the speed of light, The flight speed of the target satellite Decomposition amount in the X-axis direction, The flight speed of the target satellite The decomposition amount in the Y-axis direction. This represents the position of the target satellite along the X-axis. This represents the position of the target satellite along the Y-axis. The value of the target satellite's position in the Z-axis direction or the target satellite's altitude, the target satellite's position ( , , The location is determined based on the target satellite's position information.

[0047] In this way, the position based on the target satellite can be achieved ( , , ), the flight speed of the target satellite The second compensation parameter is determined based on the carrier frequency of the target satellite, the second position determined based on the synchronization parameters and range information of the source satellite. and This allows the terminal equipment to use the first compensation parameter for satellite switching.

[0048] In one possible implementation, the first signal is system information block type 19, in which the beam range information of the source satellite and the target satellite information are carried.

[0049] In this way, the source satellite can broadcast its beam range information and target satellite information to the terminal device via System Information Block Type 19 (SIB19). This allows the terminal device to use the source satellite's beam range information and the target satellite information to determine the compensation parameters for sending the SR to the target satellite. The SR sent to the target satellite can be, for example, a first SR or a second SR. The compensation parameters can be, for example, a first compensation parameter or a second compensation parameter.

[0050] In one possible implementation, the first signal also includes a service termination time, which is the time when the source satellite stops serving the geographical area where the terminal device is located, or the time when the source satellite stops providing services to the terminal device.

[0051] This allows terminal devices to prepare for satellite handover before or at the time of service termination, enabling them to promptly access the target satellite and achieve satellite communication even when the source satellite ceases to provide service.

[0052] In one possible implementation, the target satellite information includes the ephemeris information of the target satellite, the carrier frequency of the target satellite, and the time when the target satellite begins serving the geographical area where the terminal equipment is located.

[0053] Thus, the ephemeris information of the target satellite may include, for example, the target satellite's position and flight velocity. The target satellite information includes the target satellite's ephemeris information so that the terminal device can determine compensation parameters based on the target satellite's ephemeris information and carrier frequency. Compensation parameters may include, for example, a first compensation parameter and / or a second compensation parameter. The target satellite information includes the time when the target satellite begins serving the geographical area where the terminal device is located, so that the terminal device can perform satellite handover at the time the target satellite begins serving the geographical area where the terminal device is located, ensuring timely access to the target satellite.

[0054] In one possible implementation, the synchronization parameter is the closed-loop synchronization parameter.

[0055] In this way, the closed-loop synchronization parameters, i.e., the synchronization parameters are determined by the source satellite's closed-loop control, can improve the accuracy of the synchronization parameters. For example, the synchronization parameters include the first TA and the first FO. The first TA can accurately reflect the round-trip transmission delay from the terminal device to the source satellite. The first FO can accurately reflect the Doppler frequency shift between the terminal device and the source satellite. This can improve the accuracy of the terminal device's position determined based on the synchronization parameters, and further improve the accuracy of the compensation parameters determined based on the terminal device's position, thereby improving the effectiveness of time-frequency pre-compensation using compensation parameters, and ultimately improving the success rate of the target satellite receiving the SR sent by the terminal device, thus improving the satellite handover success rate.

[0056] In one possible implementation, the first SR is transmitted via the target satellite's Physical Uplink Control Channel (PUCCH).

[0057] In this way, transmitting the first SR through the target satellite's Physical Uplink Control Channel (PUCCH) can reduce environmental interference with the first SR and improve the success rate of the target satellite obtaining the first SR.

[0058] In one possible implementation, the response is received via the target satellite's Physical Downlink Control Channel (PDCCH).

[0059] In this way, by receiving the response returned by the target satellite through the target satellite's Physical Downlink Control Channel (PDCCH), environmental interference with the target satellite's response can be reduced, thereby improving the success rate of the terminal device receiving the response returned by the target satellite.

[0060] Secondly, embodiments of this application provide a satellite handover method applied to a source satellite. The method includes: broadcasting a first signal to a terminal device. The first signal includes beam range information of the source satellite and target satellite information. The first signal is used to determine a first compensation parameter. The first compensation parameter is used for time-frequency pre-compensation of a first scheduling request (SR) sent by the terminal device to the target satellite. The SR is used for satellite handover. The first compensation parameter is determined based on a first position of the terminal device and the target satellite information. The first position is output by a first model when the terminal device inputs the beam range information, the altitude of the source satellite, and the latest synchronization parameters received from the source satellite into a first model. The first model is constructed from equal-delay circles, equal-Doppler lines, and beam range circles.

[0061] Thus, the first signal includes the beam range information of the source satellite and the target satellite information, so that the terminal device can use the beam range information of the source satellite to determine the location of the terminal device. The first signal includes the target satellite information, so that the terminal device can use the location of the terminal device and the target satellite information to determine the first compensation parameter. The first position is output by the first model when the beam range information of the source satellite, the altitude of the source satellite, and the latest synchronization parameters received by the terminal device (i.e., UE) from the source satellite are input into the first model. The determination of the first position is independent of GNSS positioning and also independent of the SSB of the target satellite. That is, the determination of the first position does not depend on GNSS positioning or the SSB of the target satellite. Regardless of whether the terminal device can measure the SSB of the source satellite and the target satellite, and regardless of whether the terminal device can perform GNSS positioning, the terminal device can use the satellite handover method provided in this application embodiment to perform satellite handover. The satellite handover method provided in this application embodiment can reduce the probability of a reduced satellite handover success rate due to the terminal device's inability to simultaneously measure the SSB of the source satellite and the target satellite and the terminal device's inability to perform GNSS positioning. In scenarios involving hard handover of terminal devices or where GNSS positioning is not possible (such as GNSS-only scenarios), this method can improve the success rate of satellite handover for terminal devices. The first position is determined by a first model constructed from equal-delay circles, equal-Doppler lines, and beam range circles, based on the source satellite's beam range information, altitude, and the latest received synchronization parameters from the source satellite. This allows for the geometric constraint determination of the terminal device's first position using equal-delay circles, equal-Doppler lines, and beam range circles on the beam range information, source satellite altitude, and the latest received synchronization parameters from the source satellite. This improves the accuracy of terminal device position determination, thereby enhancing the accuracy of the first compensation parameters based on the terminal device's position. This, in turn, increases the success rate of the target satellite receiving the first SR (Signal Range), thus improving the success rate of the terminal device accessing the target satellite and ultimately increasing the satellite handover success rate. The source satellite's beam range information includes the source satellite's beam radius and beam center position.

[0062] Thirdly, embodiments of this application provide a satellite handover method applied to a target satellite. The method includes: receiving a scheduling request (SR) from a terminal device, the SR being used for satellite handover; compensation parameters for time-frequency pre-compensation of the SR being determined by the terminal device based on the terminal device's location and target satellite information received by the terminal device from a source satellite; the terminal device's location being output by a first model after the terminal device inputs beam range information from the source satellite, the source satellite's altitude, and the latest received synchronization parameters from the source satellite into a first model; the first model is constructed from equal-delay circles, equal-Doppler lines, and beam range circles; and sending a response to the terminal device, the response indicating successful satellite handover.

[0063] In this way, the target satellite receiving the SR from the terminal device and sending a response to the terminal device indicates that the target satellite has granted permission for the terminal device to access the target satellite. The response indicates a successful satellite handover. Sending a response to the terminal device allows the terminal device to conduct satellite communication through the NTN network where the target satellite resides. The location of the terminal device is output by the first model after inputting the source satellite's beam range information, the source satellite's altitude, and the latest synchronization parameters received by the terminal device (i.e., the UE) from the source satellite. The determination of the terminal device's location is independent of GNSS positioning and the target satellite's SSB. That is, the determination of the terminal device's location does not depend on GNSS positioning or the target satellite's SSB. This can improve the success rate of satellite handover for the terminal device in hard handover scenarios or scenarios where the terminal device cannot perform GNSS positioning (such as GNSS-free scenarios).

[0064] In one possible implementation, the method further includes: the SR from the terminal device can be either a first SR or a second SR. The compensation parameter can be either a first compensation parameter or a second compensation parameter. The location of the terminal device can be either a first location or a second location. The first compensation parameter is related to the first location, and the second compensation parameter is related to the second location. For example, the first compensation parameter is determined by the terminal device based on the first location of the terminal device and target satellite information. The second compensation parameter is determined by the terminal device based on the second location of the terminal device and target satellite information. The first compensation parameter is used for time-frequency pre-compensation of the first SR. The second compensation parameter is used for time-frequency pre-compensation of the second SR.

[0065] Thus, given the first and second positions output by the first model, the terminal device's position could be either the first or the second position. Therefore, the terminal device can sequentially use the first compensation parameter corresponding to the first position and the second compensation parameter corresponding to the second position to perform RACH-less handover. If the target satellite does not receive the first SR, and the RACH-less handover based on the first compensation parameter fails, the terminal device can apply the second compensation parameter to send a second SR to the target satellite to perform RACH-less handover again. This approach, enabling sequential RACH-less handover or sequential RACH-less detection using possible positions when the terminal device's position is ambiguous, improves the success rate of satellite handover and facilitates rapid access to the target satellite. Receiving a response from the target satellite before the second timer expires indicates either a successful satellite handover or a successful sequential RACH-less detection, allowing the terminal device to communicate via the NTN network where the target satellite resides.

[0066] Fourthly, embodiments of this application provide a communication system comprising a satellite and a terminal device. The satellite is used to execute the methods described in the second aspect, the third aspect, or any possible implementation thereof, and the terminal device is used to execute the methods described in the first aspect or any possible implementation thereof.

[0067] Fifthly, embodiments of this application provide a communication system comprising: a source satellite, a target satellite, and a terminal device. The source satellite can be used to broadcast a first signal, the first signal including beam range information of the source satellite and target satellite information. The terminal device can be used to receive the first signal from the source satellite and also to send a first scheduling request (SR) to the target satellite. The SR is used for satellite handover. The first compensation parameter for time-frequency pre-compensation of the first SR is determined based on the first position of the terminal device and the target satellite information. The first position is output by the first model after inputting the beam range information, the altitude of the source satellite, and the latest received synchronization parameters from the source satellite into the first model. The first model is constructed from equal-delay circles, equal-Doppler lines, and beam range circles.

[0068] In one possible implementation, the target satellite can be used to send a response to the terminal device upon receiving the first SR, the response indicating that the satellite handover was successful.

[0069] In one possible implementation, the terminal device can also be used to start a first timer. If the first timer times out and no response is received from the target satellite, the terminal device can also be used to send a second SR to the target satellite. The second compensation parameter for the time-frequency pre-compensation of the second SR is determined based on the second position of the terminal device and the target satellite information. The second position is output by the first model when the beam range information, the altitude of the source satellite, and the synchronization parameters are input into the first model.

[0070] In one possible implementation, the target satellite can also be used to send a response to the terminal device upon receiving a second SR, the response indicating that the satellite handover was successful.

[0071] Sixthly, embodiments of this application provide a satellite, including a processor and a memory. The memory stores computer-executable instructions. The processor executes the computer-executable instructions stored in the memory, causing the satellite to perform the methods described in any possible implementation of the second, third, or fourth aspect.

[0072] In a seventh aspect, embodiments of this application provide a satellite switching device, which may be an electronic device, or a chip or chip system within an electronic device. The satellite switching device may include a display unit and a processing unit. When the satellite switching device is an electronic device, the display unit may be a display screen. The display unit is used to perform display steps to enable the electronic device to implement a satellite switching method described in the first aspect or any possible implementation of the first aspect. When the satellite switching device is an electronic device, the processing unit may be a processor. The satellite switching device may further include a storage unit, which may be a memory. The storage unit is used to store instructions, and the processing unit executes the instructions stored in the storage unit to enable the electronic device to implement a satellite switching method described in the first aspect or any possible implementation of the first aspect. When the satellite switching device is a chip or chip system within an electronic device, the processing unit may be a processor. The processing unit executes the instructions stored in the storage unit to enable the electronic device to implement a satellite switching method described in the first aspect or any possible implementation of the first aspect. The storage unit can be a storage unit inside the chip (e.g., a register, cache, etc.) or a storage unit located outside the chip within the electronic device (e.g., a read-only memory, random access memory, etc.).

[0073] Eighthly, embodiments of this application provide a terminal device including a processor and a memory, the memory being used to store computer execution instructions, and the processor being used to run the computer execution instructions stored in the memory to perform the method described in the first aspect or any possible implementation of the first aspect.

[0074] Ninthly, embodiments of this application provide a computer-readable storage medium storing a computer program or instructions that, when executed on a computer, cause the computer to perform the methods described in the first aspect or any possible implementation thereof.

[0075] In a tenth aspect, embodiments of this application provide a computer program product including a computer program, which, when run, causes the computer to perform the method described in the first aspect or any possible implementation thereof.

[0076] Eleventhly, this application provides a chip or chip system including at least one processor and a communication interface. The communication interface and the at least one processor are interconnected via a circuit. The at least one processor is used to run computer programs or instructions to perform the methods described in the first aspect or any possible implementation thereof. The communication interface in the chip can be an input / output interface, pins, or circuits, etc.

[0077] In one possible implementation, the chip or chip system described above in this application further includes at least one memory storing instructions. The memory can be an internal storage unit of the chip, such as a register or cache, or it can be a storage unit of the chip itself (e.g., read-only memory, random access memory, etc.).

[0078] It should be understood that aspects four to eleven of this application correspond to the technical solutions of aspect one of this application, and aspects five, six, and nine to eleven of this application correspond to the technical solutions of aspects two and three of this application. The beneficial effects achieved by each aspect and the corresponding feasible implementation are similar, and will not be described again. Attached Figure Description

[0079] Figure 1 A comparative schematic diagram of soft handover and hard handover provided in an embodiment of this application;

[0080] Figure 2 This is a schematic flowchart of a satellite handover method provided in an embodiment of this application;

[0081] Figure 3 A schematic diagram of an equal-delay circle provided in an embodiment of this application;

[0082] Figure 4 A comparative diagram of UE locations provided in an embodiment of this application;

[0083] Figure 5 Another schematic flowchart of the satellite handover method provided in the embodiments of this application;

[0084] Figure 6 This is another schematic flowchart of the satellite handover method provided in the embodiments of this application. Detailed Implementation

[0085] To facilitate a clear description of the technical solutions in the embodiments of this application, some terms and technologies involved in the embodiments of this application will be briefly introduced below.

[0086] In the embodiments of this application, terms such as "first" and "second" are used to distinguish identical or similar items with substantially the same function and purpose. For example, "first chip" and "second chip" are used only to distinguish different chips and do not limit their order of execution. Those skilled in the art will understand that terms such as "first" and "second" do not limit the quantity or execution order, and that "first" and "second" do not necessarily imply that they are different.

[0087] It should be noted that, in the embodiments of this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0088] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, a--c, bc, or abc, where a, b, and c can be single or multiple.

[0089] The technical solutions of this application can be applied to various communication systems, such as: Long Term Evolution (LTE) systems, LTE Frequency Division Duplex (FDD) systems, LTE Time Division Duplex (TDD) systems, Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) communication systems, 5th Generation (5G) systems, New Radio (NR) systems, 6th Generation Mobile Communication Technology (6G) systems, or future evolution communication systems, etc.

[0090] The communication system may include a radio access network (RAN) and a core network (CN). The RAN may include RAN nodes and / or terminal equipment. Terminal equipment can connect to RAN nodes wirelessly. RAN nodes can connect to the core network wirelessly or via wired connections.

[0091] The RAN node involved in the embodiments of this application can be a device that communicates with terminal equipment. The RAN node can also be referred to as a RAN entity, access node, access network device, or radio access network device, etc. The RAN node can be a base station, a transmission reception point (TRP), an evolved NodeB (eNB or eNodeB) in an LTE system, a home base station (e.g., home evolved NodeB, or home Node B, HNB), a base band unit (BBU), a radio controller in a cloud radio access network (CRAN) scenario, or a relay station, access point, vehicle-mounted device, wearable device, or network device in a 5G network or a future evolved PLMN network, etc. It can also be an access point (AP) in a WLAN, or a next-generation NodeB (gNB) in a new radio (NR) system, etc. The aforementioned RAN node can also be a city base station, micro base station, pico base station, femtobase station, etc., and this application does not limit this.

[0092] In scenarios where RAN nodes are deployed off-ground, the RAN node can be a non-terrestrial device within an off-ground network (NTN). Off-ground communication based on NTN offers advantages such as wide coverage, long communication distance, high reliability, high flexibility, and high throughput, and it can make communication unaffected by geographical environment, climate conditions, and natural disasters. For example, NTN can provide communication services to remote areas, oceans, polar regions, and other areas where terrestrial base stations have difficulty providing coverage.

[0093] Non-ground equipment in NTN can include satellites, drones, or high-altitude platforms. Taking satellites as an example, satellite orbits can be categorized by altitude into low Earth orbit (LEO), medium Earth orbit (MEO), geostationary earth orbit (GEO), and inclined geosynchronous orbit (IGSO). Geostationary orbit can also be called a geostationary orbit. The orbital altitude of an inclined geosynchronous orbit can be the same as that of a geostationary orbit.

[0094] Satellites operating in LEO (Less-Oriented Space) can be called LEO satellites. Satellites operating in MEO (Medium-Oriented Space) can be called MEO satellites. Satellites operating in GEO (Geostationary Earth Orbit) can be called GEO satellites.

[0095] The terminal devices in this application embodiment may include handheld devices, vehicle-mounted devices, etc., with wireless connectivity. For example, some terminal devices can be: mobile phones, tablets, PDAs, laptops, mobile internet devices (MIDs), virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless communication capabilities, computing devices or other processing devices connected to a wireless modem, in-vehicle devices, terminal devices in 5G networks, or future evolution of public land mobile communication networks (PLTs). Terminal devices in a mobile network (PLMN), etc., are not limited to this in the embodiments of this application.

[0096] By way of example and not limitation, in this embodiment, the terminal device can also be a wearable device. Wearable devices, also known as wearable smart devices, are a general term for devices that utilize wearable technology to intelligently design and develop everyday wearables, such as glasses, gloves, watches, clothing, and shoes. Wearable devices are portable devices that are worn directly on the body or integrated into the user's clothing or accessories. Wearable devices are not merely hardware devices, but also achieve powerful functions through software support, data interaction, and cloud interaction. Broadly speaking, wearable smart devices include those that are feature-rich, large in size, and can achieve complete or partial functions without relying on a smartphone, such as smartwatches or smart glasses, as well as those that focus on a specific type of application function and require the use of other devices such as smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0097] Furthermore, in this embodiment, the terminal device can also be a terminal device in an Internet of Things (IoT) system. IoT is an important component of the future development of information technology. Its main technical feature is to connect objects to the network through communication technology, thereby realizing an intelligent network of human-machine interconnection and object-to-object interconnection.

[0098] The terminal equipment in this application embodiment can also be referred to as: user equipment (UE), mobile station (MS), mobile terminal (MT), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication equipment, user agent, or user device, etc.

[0099] Next, a brief introduction to some of the terminology used in the embodiments of this application will be provided:

[0100] 1. Quasi-earth fixed cell (QEFC)

[0101] In the 3rd generation partnership project (3GPP) specification, QEFC is defined as: an NTN cell that is fixed relative to a specific geographical area on Earth within a specific time period, which can cover one geographical area for a limited time and then cover another area (such as the scenario where NGSO satellites generate maneuverable beams).

[0102] QEFC can be considered an NTN cell type as defined in the 3GPP NR NTN standard. QEFC can be understood as a dynamic coverage scheme where a non-geostationary orbit (NGSO) satellite uses beam control technology to maintain fixed coverage of an NTN cell relative to a specific geographical area for a preset time period, subsequently switching to other geographical areas. QEFC differs from fixed Earth cells that maintain constant coverage and mobile Earth cells that move with the satellite.

[0103] Non-geostationary orbit (NGSO) satellites, such as LEO satellites and / or MEO satellites.

[0104] 2. Satellite switching

[0105] To provide continuous service coverage to terrestrial users, NTN communication systems based on satellite constellations can employ QEFC technology. An NTN communication system can be understood as a communication system that includes NTN (or satellites).

[0106] Taking LEO satellites as an example of non-terrestrial equipment, in QEFC technology, the geographical location of the serving cell (or beam) on the ground remains relatively fixed. LEO satellites in the NTN communication system can fly over the geographical location corresponding to the serving cell at high speed. When an LEO satellite leaves the geographical location corresponding to the serving cell, it can relay control of the serving cell to the next satellite. This process can be called satellite handover. Satellite handover can also be called inter-SAN handover. In the embodiments of this application, the serving cell can be called an NTN cell.

[0107] For example, an NTN communication system may include satellite A and satellite B. The beam of satellite A can cover geographic area 1 during time period 1. The beam of satellite B can cover geographic area 1 during time period 2. Time period 2 is later than time period 1; for example, the start time of time period 2 is later than or equal to the end time of time period 1.

[0108] During time period 1, satellite A has control over the serving cell corresponding to geographic region 1. Before or when satellite A's beam no longer covers geographic region 1, satellite A can transfer control of the serving cell of geographic region 1 to satellite B in a relay manner, so that during time period 2, satellite B has control over the serving cell corresponding to geographic region 1.

[0109] During time period 1, a UE within geographic region 1 can communicate with satellite A. If satellite A's beam does not cover geographic region 1, for example, during time period 2, a UE within geographic region 1 can establish a communication connection with satellite B. This enables satellite handover for the UE.

[0110] 3. Soft handover and hard handover

[0111] Soft handover can be understood as the UE synchronizing with the target satellite in advance, ensuring a smooth transition, while the source satellite is providing services to the UE. Soft handover requires that the beams of the source and target satellites overlap in time, and the UE must be able to monitor the signals of both satellites simultaneously within a preset time period. The overlap in time between the source and target satellite beams can be understood as beam overlap between the source and target satellites.

[0112] Hard handover can be understood as a handover method where the UE can only begin synchronizing with the target satellite after the source satellite has stopped providing services to the UE. During the entire hard handover process, there is a period of time during which the UE cannot receive satellite signals.

[0113] Figure 1 This is a comparative diagram of soft handover and hard handover provided in an embodiment of this application.

[0114] The NTN communication system may include Figure 1 Taking source satellite A and target satellite B-1 as shown, and UE located in geographic region 1 as an example, soft handover will be explained.

[0115] like Figure 1 As shown, the time period during which the beam of source satellite A covers geographic region 1 is T. 10 -T 11 Time period. The time period during which the beam of target satellite B-1 covers geographic region 1 is T. 20 -T 21 Time period. The starting time T of the geographical area 1 covered by the beam of target satellite B-1. 20 The termination time T of the beam coverage of geographic region 1 earlier than that of source satellite A 11 There is beam overlap between source satellite A and target satellite B-1.

[0116] The UE can be at the beam overlap time T 20 Synchronization with target satellite B-1 begins so that after the termination of the beam coverage of geographic area 1 of source satellite A, the UE can establish a communication connection with target satellite B-1, achieving a smooth transition from source satellite A to target satellite B-1.

[0117] The NTN communication system may include Figure 1 Taking source satellite A and target satellite B-2 as shown, and UE located in geographic region 1 as an example, we will explain hard handover.

[0118] like Figure 1 As shown, the time period during which the beam of target satellite B-2 covers geographic region 1 is T. 30 -T 31 Time period. The starting time T of the geographical area 1 covered by the beam of target satellite B-2. 30 The termination time T of the beam coverage of geographic region 1 after source satellite A 11 There is no beam overlap between source satellite A and target satellite B-2, and at T... 11 -T 30 Geographic region 1 has no satellite beam coverage during the time period. In T... 11 -T 30 During this period, the UE is unable to receive satellite signals from the satellites in the NTN communication system.

[0119] The UE can start covering geographic area 1 at time T of target satellite B-2. 30 Synchronization with target satellite B-2 begins so that, in geographical area 1 covered by the beam of target satellite B-2, the UE can establish a communication connection with target satellite B-2 and switch from source satellite A to target satellite B-2.

[0120] 4. RACH-less

[0121] To support high-speed satellite mobility, reduce satellite handover latency, and enable UEs to access satellites or the NTN network where satellites reside more quickly, the 3rd generation partnership project (3GPP) technical specification (TS) TS38.300 version 18 (Rel 18) introduced random access-free access.

[0122] For example, before an inter-satellite handover, the source satellite can transmit the UE's context, including security keys, bearer information, and measurement reports, to the target satellite via an inter-satellite link (ISL). The source satellite can then instruct the UE when to handover. Based on the information transmitted by the source satellite, the target satellite can reserve specific uplink resources for the UE in advance, or configure dedicated scheduling request (SR) resources for the UE in advance.

[0123] When the UE receives a handover command (mobility from EUTRA command or RRCreconfiguration) from the source satellite, the UE can send SR on the uplink channel of the target satellite to perform RACH-less handover.

[0124] Handover without random access can also be understood as handover without random access (HO).

[0125] 5. Satellite Access Network (SAN)

[0126] A SAN can be understood as a network component consisting of satellites and related ground equipment. The SAN is responsible for connecting the UE to the core network (CN). Related ground equipment includes, for example, gateway stations (GWs).

[0127] NTN communication systems can provide continuous communication services in areas where terrestrial base stations are difficult to cover, thus improving the user experience of satellite communication. In NTN systems, the UE needs to frequently switch between high-speed moving satellites to maintain connectivity. In some implementations, the UE can use SSB-based handover or GNSS positioning-assisted handover to switch from the source satellite to the target satellite.

[0128] Among these, handover based on SSB measurement is a soft handover, requiring overlapping beam coverage between the source and target satellites, and the UE needs to be equipped with a high-precision directional antenna to accurately receive the target satellite signal. Some UEs have very small aperture terminal (VSAT) functionality. VSAT functions include directional antennas, spatial discrimination capabilities, and angle of arrival (AoA) measurement. UEs with VSAT functionality can perform satellite handover based on SSB measurement.

[0129] For example, a UE with VSAT functionality can deduce the time-frequency synchronization parameters between the UE and the target satellite by measuring the SSB signal strength, timing difference, and frequency difference between the source and target satellites simultaneously. This simultaneous time period can be concurrent. The UE can then use the derived time-frequency synchronization parameters for satellite handover. Time-frequency synchronization parameters include, for example, timing advance (TA) and frequency offset (FO).

[0130] SSB-based handover methods are highly dependent on VSAT hardware such as directional antennas and high-precision compasses. For UEs lacking VSAT hardware or without VSAT functionality, satellite handover based on SSB measurements is impossible. Furthermore, in hard handover scenarios (such as when beams do not overlap) or during coverage gaps, the target satellite's beam may not cover the UE's geographical area. Therefore, neither UEs with nor without VSAT functionality can acquire the target satellite's SSB signal, leading to parameter calculation failures and ultimately, satellite handover failure.

[0131] This GNSS-based positioning-assisted handover method is suitable for UEs with GNSS positioning capabilities. UEs with GNSS positioning capabilities can obtain their three-dimensional position coordinates via GNSS. The TA and FO of the target satellite are calculated using the UE's three-dimensional position coordinates and the ephemeris information of the target satellite. The UE with GNSS positioning capabilities can then use the TA and FO of the target satellite to perform satellite handover, thus achieving the desired switchover to the target satellite. Ephemeris information may include orbital parameters and SSB time offset, among other things.

[0132] However, in GNSS denial scenarios, the UE cannot receive GNSS signals, or the GNSS signals received by the UE are unusable for determining the UE's three-dimensional position coordinates. Therefore, the UE cannot use GNSS signals to determine its three-dimensional position coordinates. Consequently, the UE cannot calculate the target satellite's TA and FO, leading to the UE's satellite handover failure.

[0133] The GNSS signal can be a radio frequency signal broadcast by a GNSS satellite in a GNSS system. The GNSS signal can be used to determine the UE's location information. Location information can include three-dimensional location coordinates. For example, the UE's location information can include the UE's three-dimensional location coordinates.

[0134] GNSS denial scenarios: For example, the UE is in an area with electromagnetic interference, where the UE cannot receive GNSS signals or the received GNSS signals cannot be used to determine the UE's location information. Alternatively, the UE is in an area where GNSS signals cannot be received, such as an urban canyon or a deeply obstructed area. Or, the UE does not have a GNSS module. Or, to reduce the power consumption of the high-power GNSS module, the UE has not enabled the GNSS module.

[0135] A GNSS module can be used to implement GNSS positioning functions, such as determining the UE's location information using received GNSS signals. UEs without a GNSS module include low-power IoT devices such as environmental sensors or monitors.

[0136] Therefore, when the UE cannot measure the SSB of the source and target satellites and cannot perform GNSS positioning, the success rate of satellite handover is low. This can lead to users being unable to use the UE for satellite communication in a timely manner due to failed satellite handovers, impacting user experience.

[0137] In some scenarios, the UE cannot measure the SSB of the source and target satellites. These scenarios include situations where the UE lacks VSAT functionality, the geographical area where the UE is located lacks satellite beam coverage, or the UE cannot measure the SSB of the target satellite while measuring the SSB of the source satellite. The UE cannot simultaneously measure the SSB of the source and target satellites, for example, in scenarios where there is no beam overlap between the source and target satellites. The UE cannot perform GNSS positioning; see the GNSS Denial scenario for details.

[0138] In view of this, embodiments of this application provide a satellite handover method, wherein the source satellite can broadcast a first signal. The UE can receive the first signal from the source satellite, and the first signal may include the beam range information of the source satellite and the target satellite information. The UE can send a first scheduling request (SR) to the target satellite. The SR can be used for satellite handover. The first compensation parameter for time-frequency pre-compensation of the first SR is determined based on the UE's first position and the target satellite information. The first position is output by the first model when the beam range information of the source satellite, the altitude of the source satellite, and the synchronization parameters from the source satellite are input into the first model. The first model is constructed by equal delay circles, equal Doppler lines, and beam range circles. The first position is output by the first model when the beam range information of the source satellite, the altitude of the source satellite, and the latest received synchronization parameters from the source satellite are input into the first model. The determination of the first position is independent of GNSS positioning and also independent of the target satellite's SSB. That is, the determination of the first position does not depend on GNSS positioning or the target satellite's SSB. Regardless of whether the UE can measure the SSB of the source and target satellites, and regardless of whether the UE can perform GNSS positioning, the UE can use the satellite handover method provided in this application embodiment to perform satellite handover. The satellite handover method provided in this application embodiment can reduce the probability of low satellite handover success rate due to the UE's inability to measure the SSB of the source and target satellites and its inability to perform GNSS positioning. The first position is a first model constructed by equal delay circles, equal Doppler lines, and beam range circles, determined based on the beam range information of the source satellite, the altitude of the source satellite, and the latest received synchronization parameters from the source satellite. It can achieve geometric constraints on the beam range information, the altitude of the source satellite, and the latest received synchronization parameters from the source satellite using equal delay circles, equal Doppler lines, and beam range circles to determine the UE's first position. This can improve the accuracy of UE position determination, and thus improve the accuracy of the first compensation parameters based on the UE position determination. This can improve the success rate of the target satellite receiving the first SR, thereby increasing the success rate of UE access to the target satellite and improving the satellite handover success rate.

[0139] Since the first compensation parameter in the satellite handover method provided in this application embodiment is independent of GNSS positioning and the SSB of the target satellite, the satellite handover method provided in this application embodiment can be applied to UEs without VSAT hardware, thus expanding the applicability of the satellite handover method provided in this application embodiment. UEs without VSAT hardware include, for example, some traditional handheld terminals without VSAT hardware. VSAT hardware includes, for example, compasses, tilt meters, and / or directional antennas used to implement VSAT functions.

[0140] The satellite handover method provided in this application can be applied to GNSS denial scenarios, as well as soft and hard handover scenarios. Hard handover scenarios include situations where there are periods of no satellite beam coverage, making it impossible to simultaneously measure the SSB signals of both the source and target satellites. The satellite handover method provided in this application does not require beam overlap between the source and target satellites; therefore, it is applicable to scenarios where there is no beam overlap between the source and target satellites.

[0141] Scenarios where there is no beam overlap between the source satellite and the target satellite can include: the start time of the target satellite's beam coverage of the geographical area where the UE is located is later than or equal to the end time of the source satellite's beam coverage of the geographical area where the UE is located. Synchronization parameters from the source satellite, such as the most recently received synchronization parameters from the source satellite by the UE.

[0142] The satellite switching method provided in this application will be described below with reference to some embodiments.

[0143] Figure 2 This is a schematic flowchart of a satellite handover method provided in an embodiment of this application.

[0144] like Figure 2 As shown, the satellite handover method provided in this application embodiment may include:

[0145] S201. The source satellite can broadcast a first signal. Correspondingly, the UE can receive the first signal from the source satellite. The first signal may include the source satellite's beam range information and the target satellite information. UE, i.e., terminal equipment.

[0146] For example, the beam range information of the source satellite may include the beam radius and beam center location of the source satellite. Beam range information can be understood as the geographical coverage area of ​​the serving cell (QEFC) provided by the UE. The beam range information of the source satellite can be used to calculate the location of the UE using geometric constraints.

[0147] Target satellite information may include the target satellite's ephemeris information, carrier frequency, and the time when the target satellite begins serving the geographic area where the UE (i.e., the terminal device) is located. The ephemeris information may include orbital parameters and / or Kepler elements. The time when the target satellite begins serving the geographic area where the UE is located can be referred to as the time when the target satellite is about to begin serving this area.

[0148] The ephemeris information of the target satellite can be used to determine the transmission delay and frequency shift between the UE and the target satellite, so as to perform time-frequency pre-compensation on the uplink signals (such as SR) used for satellite handover using transmission delay and frequency shift. This improves the success rate of the target satellite receiving the uplink signal, and thus improves the success rate of satellite handover.

[0149] By obtaining the time when the target satellite begins serving the geographical area where the UE is located, the UE can perform satellite handover at the time when the target satellite begins serving the geographical area where the UE is located, so that the UE can access the target satellite in a timely manner.

[0150] Optionally, the target satellite information may also include the time offset of the target satellite's SSB relative to the source satellite's SSB. This allows the UE to capture the SSB signal and determine the target satellite's SSB signal from the captured SSB signal, based on the time offset of the target satellite's SSB relative to the source satellite's SSB, when the target satellite's beam covers the geographical area where the UE is located.

[0151] In this embodiment of the application, the target satellite can be understood as a SAN containing the target satellite or a SAN to which the target satellite belongs. The source satellite can be understood as a SAN containing the source satellite or a SAN to which the source satellite belongs.

[0152] Taking satellite A as the source satellite and satellite B as the target satellite as an example, the SAN to which the source satellite belongs can be represented as SAN A, and the SAN to which the target satellite belongs can be represented as SAN B. The ephemeris information of the target satellite can be understood as the orbital parameters of SAN B. The time when the target satellite begins serving the geographic area where the UE is located can be understood as the time when SAN B begins serving the geographic area where the UE is located. The time offset of the target satellite's SSB relative to the source satellite's SSB can be understood as the time offset of SAN B's SSB relative to SAN A's SSB.

[0153] Optionally, the first signal may also include a service termination time. The service termination time can be understood as the time when the currently serving satellite is about to cease serving the local area. The currently serving satellite is, for example, the source satellite or SAN A. For instance, the service termination time can be understood as the time when the source satellite stops serving the geographical area where the UE is located, or as the time when the source satellite stops providing service to the UE.

[0154] This allows the UE to prepare for satellite handover before or at the time of service termination, enabling the UE to promptly access the target satellite and achieve satellite communication even when the source satellite ceases to provide service. Satellite handover preparation may include, for example, determining the UE's location and compensation parameters, such as a first compensation parameter and / or a second compensation parameter.

[0155] For example, the first signal may be system information block type 19 (SIB19). The source satellite broadcasts the first signal, for instance, via SIB19. The source satellite's beam range information and the target satellite information may be carried in the satSwitchWithReSync information element of the SIB19. The satSwitchWithReSync information element is a set of information elements that may include service time (t-service) information elements, NTN configuration (ntn-config) information elements, service start time (t-service start) information elements, and SSB time offset (ssb-time offset) information elements, etc.

[0156] For example, the service termination time can be carried in the t-service information element. The ephemeris information or orbital parameters of the target satellite can be carried in the ntn-config information element. The time when the target satellite begins serving the geographical area where the UE is located can be carried in the t-service start information element. The time offset of the target satellite's SSB relative to the source satellite's SSB can be carried in the ssb-time offset information element.

[0157] In some implementations, t-service can be represented as t-Service. ntn-config can be represented as ntn-Config. t-service start can be represented as t-Service Start. ssb-time offset can be represented as ssb-TimeOffset.

[0158] Optionally, the source satellite may broadcast a first signal before the service termination time to facilitate satellite handover preparation for UEs within the source satellite beam coverage area.

[0159] S202, the UE may send a first scheduling request (SR) to the target satellite. The SR can be used for satellite handover. The first compensation parameter for time-frequency pre-compensation used for the first SR is determined based on the UE's first location and the target satellite information.

[0160] The first position is output by the first model when the source satellite's beam range information, altitude, and synchronization parameters from the source satellite are input into the first model. The first model is constructed from equal-delay circles, equal-Doppler lines, and beam range circles. For example, the synchronization parameters from the source satellite can be the most recently received synchronization parameters from the source satellite by the terminal device.

[0161] For example, since ephemeris information can include orbital parameters, which may include the satellite's orbital altitude, i.e., the satellite's altitude, the source satellite's altitude can be obtained by the UE from the source satellite's ephemeris information. The source satellite's ephemeris information can be sent to the UE by the previous satellite of the source satellite, or it can be broadcast by the source satellite if its beam covers the geographical area where the UE is located. Optionally, the source satellite's altitude can also be preset in the UE.

[0162] The synchronization parameters of the source satellite can be closed-loop synchronization parameters from the source satellite. These parameters can be carried in the TA command sent by the source satellite to the UE, or in the first signal. The TA command can be sent periodically or non-periodically by the source satellite to the UE, or it can be sent along with user data sent to the UE. The source satellite can transmit the TA command to the UE through the MAC control element (MAC-CE). The TA command can be carried in the MAC-CE. MAC can be referred to as the media access control layer.

[0163] For example, upon receiving a first signal from a source satellite, the UE can input the source satellite's beam range information, altitude, and the latest received closed-loop synchronization parameters from the source satellite into a first model. The first model can output a first position. This is achieved by using the equal-delay circle, equal-Doppler line, and beam range circle of the first model to perform geometric constraint calculations on the source satellite's beam radius, beam center position, altitude, and the latest received closed-loop synchronization parameters, thus obtaining the first position.

[0164] The UE can determine the first compensation parameter based on the first location and the ephemeris information of the target satellite.

[0165] When the target satellite's beam covers the geographical area where the UE is located, the UE can use the first compensation parameter to perform time-frequency pre-compensation on the first SR before transmitting it, so as to improve the success rate of the target satellite receiving the first SR, and thus improve the success rate of the UE accessing the target satellite.

[0166] For example, the first compensation parameter may include a time delay TA determined based on the ephemeris information of the first position and the target satellite.B1 and frequency shift FO B1 When the target satellite's beam covers the geographical area where the UE is located, the UE can use TA. B1 and FO B1 Time-frequency pre-compensation is performed on the first SR to obtain the adjusted transmission timing and the frequency-adjusted first SR. The UE can then transmit the frequency-adjusted first SR to the target satellite at the adjusted transmission timing. This reduces the probability of the target satellite failing to receive the first SR due to transmission delay and frequency shift between the UE and the target satellite, thereby improving the success rate of the UE accessing the target satellite.

[0167] like Figure 2 As shown in the embodiments of this application, in the satellite handover method, the first signal broadcast by the source satellite may include the source satellite's beam range information and the target satellite information. This allows the UE to perform geometric constraint calculations on the source satellite's beam range information, the source satellite's altitude, and the UE's latest received synchronization parameters from the source satellite using equal delay circles, equal Doppler lines, and beam range circles to obtain the UE's first position. This achieves the determination of the UE's first position through calculations of the source satellite's beam range information, altitude, and synchronization parameters without requiring the UE to perform GNSS positioning or measure the target satellite's SSB. This allows the UE to use the first compensation parameters determined based on the first position and target satellite information to perform time-frequency pre-compensation for the uplink from the UE to the target satellite, thereby improving the success rate of the target satellite receiving the first SR (Signal Receiver) using the first compensation parameters, and thus improving the success rate of the UE accessing the target satellite and achieving satellite handover. The SR can be used to request the allocation of uplink resources.

[0168] The determination of the primary location does not depend on GNSS positioning or the SSB of the target satellite. Regardless of whether the UE can simultaneously measure the SSB of both the source and target satellites, or whether it can perform GNSS positioning, the satellite handover method provided in this application embodiment can be used for satellite handover. The satellite handover method provided in this application embodiment can reduce the limitations imposed on the UE's hardware capabilities by satellite handover. For example, it can eliminate the requirement that the UE has VSAT functionality and / or GNSS positioning functionality for satellite handover. Furthermore, it can expand the range of UEs to which the satellite handover method provided in this application embodiment is applicable, such as expanding the types and categories of UEs to which the satellite handover method provided in this application embodiment is applicable.

[0169] The satellite handover method provided in this application can reduce the probability of low satellite handover success rates due to the UE's inability to simultaneously measure the SSB of both the source and target satellites and its inability to perform GNSS positioning. The first position is determined by a first model constructed from equal-delay circles, equal-Doppler lines, and beam range circles, based on the source satellite's beam range information, altitude, and synchronization parameters. This method uses equal-delay circles, equal-Doppler lines, and beam range circles to geometrically constrain the source satellite's beam range information, altitude, and synchronization parameters to determine the UE's first position. This improves the accuracy of UE position determination, and consequently, the accuracy of the first compensation parameters based on the UE's position. This, in turn, increases the success rate of UE accessing the target satellite, thereby improving the satellite handover success rate.

[0170] Compared to GNSS positioning-assisted handover methods, which are unsuitable for GNSS denial scenarios, the satellite handover method provided in this application is applicable to GNSS denial scenarios. Compared to SSB-based handover methods, which are unsuitable for hard handover scenarios, the satellite handover method provided in this application is applicable to both soft and hard handover scenarios. The satellite handover method provided in this application is applicable to SSB scenarios where the UE cannot measure the source and target satellites' SSBs.

[0171] The following is a detailed explanation of S202.

[0172] For example, the synchronization parameters of the source satellite may include a first time advance (TA) and a first frequency offset (FO).

[0173] The first TA (Transmission Time Allocation) can be determined by the source satellite through continuous closed-loop control via TA commands, accurately reflecting the round-trip transmission delay from the UE to the source satellite. The first FO (Frequency Forward Time) can also be determined by the source satellite's closed-loop control, accurately reflecting the Doppler frequency shift between the UE and the source satellite. Using the first TA and first FO to determine the UE's location improves the accuracy of UE location determination. This, in turn, improves the accuracy of the first compensation parameter based on the UE's location determination, enabling effective time-frequency pre-compensation of uplink signals such as the first SR (Signal Receiver) using the first compensation parameter, thereby increasing the success rate of the target satellite receiving the first SR.

[0174] For example, the first model can be referred to as the geometric constraint model. The first model may include constraint 1 based on the equal-time-delay circle, constraint 2 based on the equal-Doppler line, and constraint 3 based on the beam range circle. The first model may be a set of equations consisting of the equal-time-delay circle equation, the equal-Doppler line equation, and the beam range circle constraint equation. This set of equations is the equation set of the first model.

[0175] Taking a coordinate system with the satellite's nadir as the origin and the positive X-axis as the satellite's flight direction as an example, the equations of the first model can be expressed as equation (1):

[0176] (1)

[0177] in, This is the equation or formula for the circle of equal time delay. This refers to the equation of the equal Doppler line, the formula for the equal Doppler line, or the hyperbola formula. This refers to the beam range circle constraint equation or the beam range constraint formula. Let E be the radius of the isochronous delay circle. Let E be the length of the real semi-axis. Let F be the length of the imaginary semi-axis. The radius of the beam range circle or the satellite beam radius. These are the coordinates of the beam center point. x and y are the parameters to be calculated. The beam is the satellite beam. The nadir point can be found in [reference needed]. Figure 3 Description of the sub-satellite point in the illustrated embodiment.

[0178] Figure 3 This is a schematic diagram of an equal-delay circle provided in an embodiment of this application.

[0179] like Figure 3 As shown, the center of the equal-delay circle 301 is O, and the distance from the center O to the UE on the equal-delay circle 301 is... That is, the radius of the isochronous delay circle 301 is... The center O is the nadir point of the satellite. The distance from the center O to the satellite is the satellite altitude H. The distance between the satellite and the UE is d. The formula can be satisfied:

[0180]

[0181] The coordinate system in this embodiment can be a coordinate system established with the satellite's nadir point as the origin and the positive X-axis direction as the satellite's flight direction. The satellite's nadir point is the center of the satellite's isochronous delay circle. The satellite's coordinates can be represented as (0, 0, H). The coordinates of a point on the isochronous delay circle can be represented as (x, y, 0).

[0182] The equations for the iso-Doppler lines are derived based on the Doppler formula. For example, see [link to example]. Figure 3 The diagram shows a satellite and a user equipment (UE), with the UE located on an equal-delay circle. Taking the UE's position on the X-axis as x and on the Y-axis as y, and the satellite flying along the X-axis at a speed of v as an example, the Doppler shift in signal transmission between the satellite and the UE is illustrated. The formula can be satisfied:

[0183]

[0184] The distance d between the satellite and the UE can satisfy the formula:

[0185]

[0186] Taking the correction factor K as a dimensionless coefficient that includes frequency offset as an example, K can satisfy the formula:

[0187]

[0188] in, This refers to the satellite's carrier frequency. for The public parts. for The dedicated part. c is the speed of light. For example, c ≈ 3 × 10 8 meters per second.

[0189] Substitute K into The formula can be obtained as follows:

[0190]

[0191] For the formula Squaring both sides and rearranging, we obtain the equation for the equal Doppler lines, where F = H and E satisfies the formula:

[0192]

[0193] For example, the source satellite's beam range information, altitude, and closed-loop synchronization parameters are input into the first model, and the first model outputs the first position. This can be understood as follows: the first position is calculated by the UE by substituting the source satellite's beam range information, the source satellite's altitude, the first TA, and the first FO into the equations of the first model.

[0194] For example, the beam radius R of the source satellite beam,A The beam center position of the source satellite (x) c,A y c,A ,0), the altitude H of the source satellite A Inputting the first TA and the first FO into the first model, we can obtain the result in R. T =R TA E=E A F=F A x c =x c,A y c =y c,A And R beam =R beam,A The system of equations (2) for time:

[0195] (2)

[0196] Among them, R TA E is the radius of the first equal-time-delay circle. AF is the length of the real semi-axis of the first-order Doppler line. A F is the imaginary semi-axis length of the first-order Doppler line. A =H A R beam,A Let be the beam radius of the source satellite, and also the radius of the first beam range circle. Equation set (2) can be understood as including the equation of the first time delay circle. The first Doppler line equation and the first beam range circular constraint equation The system of equations. The value of the beam center position of the source satellite in the X-axis direction. This represents the position of the source satellite's beam center along the Y-axis. The coordinates of the source satellite's beam center point, or the position of the source satellite's beam center, can be expressed as... .

[0197] The coordinate system corresponding to equation (2) can be understood as the coordinate system when the satellite is the source satellite. That is, the coordinate system corresponding to equation (2) is a coordinate system with the origin at the nadir point of the source satellite and the positive X-axis direction being the flight direction of the source satellite. The nadir point of the source satellite is the center of the first equal time delay circle.

[0198] The UE can solve equation (2) to obtain the UE position. The UE position may include a first position and / or a second position.

[0199] The first isochronous delay circle is based on the first TA and the altitude H of the source satellite. A Yes, it is determined. The first Doppler line is determined based on the first FO, the flight direction of the source satellite, and the flight speed of the source satellite. The radius of the first beam range circle is the beam radius of the source satellite.

[0200] The first-order time delay circle can be understood as d = ... And H is The isochronous delay circle. Alternatively, the first isochronous delay circle can be understood as having a radius of . Equal-time delay circle. This represents the distance between the source satellite and the UE. This refers to the altitude of the source satellite or its orbital altitude. The distance between the source satellite and the UE. It can be obtained by the UE calculating the first TA.

[0201] For example, the first TA is TA. A For example, the straight-line distance between the source satellite and the UE The formula can be satisfied:

[0202]

[0203] in, This refers to the round-trip time from the UE to the source satellite. Public delay compensation or public delay compensation configured for the serving cell of the source satellite. It can be obtained by the UE from SIB19 broadcast by the source satellite. It can be carried in the ntn-config information element of SIB19. It can also be preset. Optionally, the first signal may also include .

[0204] The formula can be satisfied:

[0205]

[0206] The first Doppler line can be understood as E = E. A And F is F A E-Doppler lines at time. A It can be obtained by the UE calculating the first FO. .

[0207] For example, let the first FO be FO. A For example, E A The formula can be satisfied:

[0208]

[0209] The correction factor K can be the Doppler frequency shift that includes the signal transmission between the source satellite and the UE. Dimensionless coefficients. For example, K can satisfy the formula:

[0210]

[0211] in, The carrier frequency of the source satellite. It can be a preset value. This refers to the common frequency compensation for the source satellite or the common frequency compensation configured for the serving cell of the source satellite. For the first FO. The speed or velocity of the source satellite.

[0212] Satellite ephemeris information (such as orbital parameters) can include the satellite's flight speed or orbital speed. This can be obtained by the UE from the ephemeris information of the source satellite. Carrier frequency. It can be pre-set in the UE, or it can be obtained by the UE from the signal broadcast by the source satellite (such as the first signal). It can be obtained by the UE from SIB19 broadcast by the source satellite. It can be carried in the ntn-config information element of SIB19. Optionally, the first signal may also include Satellites (such as the source satellite) can periodically broadcast SIB19.

[0213] The UE's position is the intersection of the equal-delay circle and the single-sided hyperbola that fall within the beam circle. For example, the UE position obtained by solving the equation set (2) can be the intersection of the first equal-delay circle and the first equal-Doppler line, and the UE position is located within the first beam range circle.

[0214] For example, the first position can be the intersection of the first equal time delay circle and the first equal Doppler line, and the first position is located within the first beam range circle.

[0215] Thus, the first position is the intersection of the first equal time delay circle and the first equal Doppler line, so that the position of the terminal equipment can be determined by the constraints of the first equal time delay circle and the first equal Doppler line. The first position is located within the first beam range circle, so that the determined position of the terminal equipment can be further constrained by the first beam range circle to determine the first position.

[0216] The second position can be the intersection of the first equal time delay circle and the first equal Doppler line, and the second position is located within the first beam range circle.

[0217] Thus, the second position is the intersection of the first equal-delay circle and the first equal-Doppler line, which allows the location of the terminal equipment to be determined by the constraints of the first equal-delay circle and the first equal-Doppler line. The second position is located within the first beam range circle, which allows for further constraints on the determined location of the terminal equipment by the first beam range circle, thereby determining the second position.

[0218] The first equal-time delay circle is determined based on the first TA and the altitude of the source satellite. The first equal-Doppler line is determined based on the first FO, the flight direction of the source satellite, and the flight velocity of the source satellite. The radius of the first beam range circle is the beam radius. It can be stated that the first and second positions are determined based on the synchronization parameters and beam range information of the source satellite. The determination of the first and second positions is independent of the target satellite's SSB and GNSS positioning.

[0219] In this way, the first and / or second positions can be determined without measuring the SSB of the target satellite or GNSS positioning. The satellite handover execution provided in this application embodiment can be performed independently of GNSS positioning and SSB measurement, making it applicable to scenarios where the SSBs of both the source and target satellites cannot be measured simultaneously, and also applicable to GNSS-only scenarios, thus expanding the application scope of the satellite handover method provided in this application embodiment.

[0220] When the satellite beam is parallel to the satellite's flight trajectory, the equal-frequency offset line and the equal-time-delay circle will necessarily intersect at two points in the ground beam projection. When the satellite beam is perpendicular to the satellite's flight trajectory, the equal-frequency offset line and the equal-time-delay circle will necessarily intersect at only one point in the ground beam projection. The equal-frequency offset line is like the equal-Doppler line. The ground beam projection is, for example, the beam range circle. The beam range circle can be simply referred to as the beam circle.

[0221] For example, by solving the system of equations (2), a first position and / or a second position can be obtained. The first position and the second position may be the same or different.

[0222] For example, when the beam of the source satellite is parallel to the flight trajectory of the source satellite, that is, when the angle between the beam of the source satellite and the flight trajectory of the source satellite is zero or 180°, the first position and the second position can be obtained by solving the equation set (2), and the first position and the second position are different.

[0223] When there is an angle between the source satellite's beam and its flight trajectory that is greater than or equal to a preset angle threshold, the first position can be obtained by solving equation (2). Taking a preset angle greater than 0° and less than 180° as an example, when the source satellite's beam is perpendicular to its flight trajectory, that is, when the angle between the source satellite's beam and its flight trajectory is 90°, the first position can be obtained by solving equation (2).

[0224] The shape of the iso-Doppler lines in the embodiments of this application is a single-sided hyperbola. A single-sided hyperbola can be understood as one branch of a hyperbola.

[0225] When the Doppler frequency shift is positive, the iso-Doppler lines are single-sided hyperbolas with the opening direction in the same direction as the satellite's orbit. That is, when the Doppler frequency shift is positive, the opening direction of the iso-Doppler lines is the same as the satellite's orbit.

[0226] When the Doppler frequency shift is negative, the iso-Doppler lines are single-sided hyperbolas with their opening direction opposite to the satellite's orbital direction. That is, when the Doppler frequency shift is negative, the opening direction of the iso-Doppler lines is opposite to the satellite's orbital direction. The Doppler frequency shift can be, for example,... or .

[0227] In one possible implementation, the iso-Doppler lines are straight lines. For example, when the Doppler frequency shift FO between the satellite and the UE is zero, all UEs with zero Doppler frequency shift FO lie on a straight line, i.e., the iso-Doppler lines are straight lines.

[0228] The following is combined Figure 4The relationship between the relative positions of the source satellite's beam and flight trajectory and the UE's position is explained. Taking the Doppler line as negative, with the first position as P1 and the second position as P2 as an example... Figure 4 This is a comparative diagram of the UE location provided in an embodiment of this application.

[0229] like Figure 4 As shown in Figure 'a', the source satellite's beam is parallel to its flight trajectory. The intersection points of the source satellite's first equal-delay circle 403 and the first equal-Doppler line 401 are P1 and P2, and P1 and P2 are located within the first beam range circle 402. The principle for determining the first equal-delay circle 403 can be found in [reference needed]. Figure 3 The specific implementation principle of the equal delay circle 301 in the illustrated embodiment. Source satellite flight trajectory, for example... Figure 4 The image shows the projection of the source satellite's flight orbit. (See also:) Figure 4 As shown in a, when the source satellite's beam is parallel to the source satellite's flight trajectory, the UE position determined by the first model is the first position P1 and the second position P2.

[0230] like Figure 4 As shown in b, when the source satellite's beam and its flight trajectory form an angle δ greater than or equal to an angle threshold, the intersection points of the source satellite's first equal-delay circle 403 and first equal-Doppler line 401 are P1 and P2. P1 is located within the first beam range circle 402. P2 is located outside the first beam range circle 402. Figure 4 As shown in b, when there is an angle δ between the source satellite beam and the source satellite flight trajectory, and δ is greater than or equal to the angle threshold, the UE position determined by the first model is the first position P1.

[0231] like Figure 4 As shown in Figure c, when the source satellite's beam is perpendicular to its flight trajectory, the intersection points of the first equal-delay circle 403 and the first equal-Doppler line 401 are P1 and P2. P1 is located within the first beam range circle 402. P2 is located outside the first beam range circle 402. Figure 4 As shown in c, when the source satellite's beam is perpendicular to the source satellite's flight trajectory, the UE position determined by the first model is the first position P1.

[0232] like Figure 4As shown, taking the equal-delay circle as the first equal-delay circle 403, the equal-Doppler line as the first equal-Doppler line 401, and the beam range circle as the first beam range circle 402 as an example, the equations for the first equal-delay circle and the first equal-Doppler line can generate at most two real solutions P1 and P2. Since the UE is located within the first beam range circle, the two real solutions P1 and P2 generated by the equations for the first equal-delay circle and the first equal-Doppler line can be filtered using the first beam range circle to obtain a candidate location set S_valid containing P1 and / or P2. S_valid = {P|P∈{P1, P2}}. P is located within the beam range circle.

[0233] For example, taking a coordinate system with the nadir point of the source satellite as the origin and the positive X-axis as the flight direction of the source satellite as an example, the coordinates of the source satellite can be (0, 0, H). A The coordinates of the first position can be (x1, y1, 0), and the first coordinates can satisfy the formula:

[0234]

[0235] in, Let be the radius of the first equal-time-delay circle. , t is the first TA. c is the speed of light.

[0236] Thus, the first coordinate satisfies This allows the obtained first coordinates to lie on the first equal-delay circle, thus implementing constraint 1 based on the first equal-delay circle to limit the UE position. The first coordinates satisfy... This allows the obtained first coordinates to lie on the first iso-Doppler line, thus further defining the UE position based on constraint 2 of the first iso-Doppler line. The first coordinates satisfy... This allows the obtained first coordinates to lie within the first beam range circle, further defining the UE position based on constraint 3 of the first beam range circle. This determines the coordinate value x1 in the X-axis direction and the coordinate value y1 in the Y-axis direction of the first coordinate. This achieves the determination of each coordinate value of the first coordinate.

[0237] For example, taking the nadir point of the source satellite as the origin and the positive X-axis as the flight direction of the source satellite as an example, the coordinates of the second position can be the second coordinates (x2, y2, 0). Based on the system of equations (2), the second position can be solved, and the second coordinates can satisfy the formula:

[0238]

[0239] Thus, the second coordinate satisfies This allows the obtained second coordinates to lie on the first equal-delay circle, thus achieving constraint 1, which limits the UE position based on the first equal-delay circle. The second coordinates satisfy... This allows the obtained second coordinates to lie on the first iso-Doppler line, thus further defining the UE position based on constraint 2 of the first iso-Doppler line. The second coordinates satisfy... This allows the obtained second coordinates to lie within the first beam range circle, further defining the UE position based on constraint 3 of the first beam range circle. This determines the coordinate values ​​x2 in the X-axis direction and y2 in the Y-axis direction of the second coordinate. This achieves the determination of each coordinate value of the second coordinate.

[0240] For example, the target satellite information may include the ephemeris information of the target satellite. The ephemeris information may include the target satellite's position, velocity, and time (PVT) information. Optionally, the target satellite information may also include the target satellite's carrier frequency. The UE can obtain the target satellite's velocity, i.e., its flight speed, from the target satellite's PVT information. .

[0241] In a coordinate system with the center of the first equal-time-delay circle as the origin and the positive X-axis as the flight direction of the source satellite, the position of the target satellite is ( , , For example, the location of the target satellite ( , , The location information can be determined by the UE based on the location information in the PVT information of the target satellite. This represents the position of the target satellite along the X-axis. This represents the position of the target satellite along the Y-axis. The value representing the position of the target satellite in the Z-axis direction or the altitude of the target satellite.

[0242] For example, the UE can use a preset algorithm to calculate the PVT information of the target satellite. For instance, the UE can use a preset algorithm to calculate the position information in the PVT information of the target satellite to obtain the position of the target satellite in the geocentric coordinate system. The UE can use a preset coordinate transformation algorithm to map the position of the target satellite in the geocentric coordinate system to a coordinate system with the nadir point of the source satellite as the origin, thus obtaining the position of the target satellite. , , ).

[0243] When the UE obtains its location using the first model, the UE can also obtain its location based on the UE's location and the location of the target satellite. , , ), the flight speed of the target satellite and the carrier frequency of the target satellite Determine the distance between the UE and the target satellite. Delay compensation and Doppler frequency deviation The UE position can be, for example, a first position and / or a second position.

[0244] To counteract the Doppler effect, the UE transmits a frequency pre-compensation value for the uplink signal to the target satellite. Should be related to Doppler frequency deviation Conversely, for example, if Doppler shift causes the frequency to increase, the UE needs to reduce the frequency of the uplink signal. Satisfying the formula:

[0245]

[0246] For example, when the UE obtains the first position using the first model, based on the first position (x1, y1, 0), the position of the target satellite, and the flight speed of the target satellite... and the carrier frequency of the target satellite The UE can determine the distance between the UE and the target satellite. for Delay compensation for UE sending uplink signals to target satellite For the first delay compensation Doppler frequency offset between UE and target satellite for Frequency pre-compensation value The first frequency pre-compensation value .

[0247] The formula can be satisfied:

[0248]

[0249] The formula can be satisfied:

[0250]

[0251] The formula can be satisfied:

[0252]

[0253] in, The flight speed of the target satellite Decomposition amount in the X-axis direction, The flight speed of the target satellite The decomposition amount in the Y-axis direction. It can represent the distance between the first position and the target satellite.

[0254] The formula can be satisfied:

[0255]

[0256] For example, when the UE obtains the second position using the first model, based on the second position (x2, y2, 0) and the position of the target satellite ( , , ), the flight speed of the target satellite and the carrier frequency of the target satellite The UE can determine the distance between the UE and the target satellite. for Delay compensation for UE sending uplink signals to target satellite For the second delay compensation Doppler frequency offset between UE and target satellite for Frequency pre-compensation value Second frequency pre-compensation value .

[0257] The formula can be satisfied:

[0258]

[0259] It can represent the distance between the second position and the target satellite.

[0260] The formula can be satisfied:

[0261]

[0262] The formula can be satisfied:

[0263]

[0264] The formula can be satisfied:

[0265]

[0266] As shown above, in the satellite handover method provided in this application embodiment, the determination of the UE position, such as the first position and / or the second position, does not rely on GNSS positioning and the SSB of the target satellite, but rather on the TA and FO closed-loop information of the source satellite. This can improve the accuracy of the determined UE position, and thus improve the accuracy of the compensation parameters determined based on the UE position. The first model in this application embodiment is constructed based on the closed-loop synchronization parameters (TA and FO) and beam range information of the source satellite, which can improve the accuracy of the position output by the first model. The first iso-Doppler line in this application embodiment is a single-sided hyperbola, and its opening direction is related to the flight trajectory direction of the source satellite. The flight trajectory direction of the source satellite is the flight direction of the source satellite.

[0267] For example, when the first model outputs a first position, the UE can base its position on the first position (x1, y1, 0) and the position of the target satellite (x1, y1, 0). , , ), flight speed and carrier frequency Determine the first compensation parameter and .

[0268] The UE can perform RACH-less handover based on a first compensation parameter. For example, the UE can apply the first compensation parameter to transmit a first SR to the target satellite on the physical uplink control channel (PUCCH). That is, the first SR can be transmitted via the target satellite's PUCCH.

[0269] For example, the UE can use a first compensation parameter to perform time-frequency pre-compensation on the first SR to obtain the adjusted transmission timing T1 and the frequency-adjusted first SR. The UE can then transmit the frequency-adjusted first SR to the target satellite via PUCCH at the adjusted transmission timing T1. This can reduce the probability of the target satellite failing to receive the first SR due to transmission delay and frequency shift between the UE and the target satellite, thereby improving the success rate of the UE accessing the target satellite.

[0270] For example, the UE can determine the synchronization time T0 based on the latest received SSB broadcast by the target satellite. For instance, the UE can detect and demodulate the primary synchronization signal (PSS) and secondary synchronization signal (SSS) of the latest received SSB signal from the target satellite to obtain the SSB reception time, i.e., the downlink reference time T. DL_ref The UE can base its decisions on the downlink reference time T. DL_ref The synchronization time T0 is determined by the preset time offset k. T0 satisfies T0=T DL_ref+k. k is the time offset specified in 3GPP protocol TS 38.214.

[0271] For example, taking T0 as T01, that is, the synchronization time determined by the UE through the latest SSB broadcast by the target satellite as T01, the UE can calculate the first delay compensation TA based on T01 and the calculated time delay compensation TA. B1 Determine the transmission timing T1. For example, the UE can use a lead time for TA. B1 The sending timing is adjusted in a way that means T1 is TA earlier than T01. B1 T1 = T01 - TA B1 The UE can adjust the frequency by an amount of FO. B1 Adjust the frequency of the first SR to obtain the frequency-adjusted first SR.

[0272] The UE can send the frequency-adjusted first SR to the target satellite via PUCCH at time T1, so that the first SR is aligned with the uplink time window of the target satellite when it arrives at the target satellite, thereby improving the success rate of the target satellite receiving the first SR and thus improving the success rate of accessing the target satellite.

[0273] Figure 5 This is another schematic flowchart illustrating the satellite handover method provided in an embodiment of this application.

[0274] For example, when the UE obtains a first location using the first model but does not obtain a second location, the satellite handover method provided in this application embodiment can be found in [reference needed]. Figure 5 The embodiment shown. As... Figure 5 As shown, the satellite handover method provided in this application embodiment may include S201, S202, and S501-S502, or may include S201, S202, S501, and S503. The specific implementation principles of S201-S202 can be found in [reference needed]. Figure 2 The specific implementation principle of the illustrated embodiment will not be elaborated here.

[0275] S501, the UE can start the first timer to monitor scheduling clearance on the physical downlink control channel (PDCCH).

[0276] For example, when sending the first SR, the UE can start a first timer. The first timer can be a fallback timer (T_fallback). Alternatively, the first timer can also be a probe timer (T_probe).

[0277] S502, Before the first timer expires, the target satellite may return a response to the UE upon receiving the first SR. Correspondingly, before the first timer expires, the UE may receive a response from the target satellite. The response may be used to indicate successful satellite handover. The response may be received via the target satellite's PDCCH.

[0278] For example, before the first timer expires, the target satellite can return a response to the UE via PDCCH upon receiving the first SR. Correspondingly, the UE can monitor the response returned by the target satellite via PDCCH, which can indicate that the satellite handover was successful. This response can indicate scheduling permission or can be used to indicate that the satellite handover was successful.

[0279] SR can be used to request the allocation of uplink resources. The response returned by the target satellite via PDCCH can be understood as a response to the SR sent by the UE to the target satellite, and the response may include uplink grant.

[0280] Optionally, the response may also include scheduling information. The scheduling information can be used to indicate the time and frequency resources of the physical downlink shared channel (PDSCH) and / or the physical uplink shared channel (PUSCH). This facilitates the UE receiving data via the PDSCH on the time and frequency resources of the PDSCH. It also facilitates the UE transmitting data to the target satellite via the PUSCH on the time and frequency resources of the PUSCH.

[0281] In this way, the UE can conduct satellite communication through the NTN network where the target satellite is located.

[0282] S503. If the first timer expires and no response is received from the target satellite, the UE may fall back to the Physical Random Access Channel (PRACH) random access procedure.

[0283] For example, if the UE does not detect a response from the target satellite via PDCCH when the first timer expires, it may indicate a satellite handover failure or a RACH-less handover failure. The UE can then fall back to the PRACH random access procedure.

[0284] In this way, the UE can perform PRACH random access to access the target satellite through the PRACH random access procedure, thereby realizing satellite handover.

[0285] like Figure 5As shown in the satellite handover method provided in this application embodiment, when the candidate location set S_valid determined by the terminal device (i.e., UE) using the first model contains only one solution P1 (i.e., the first location), the UE location is uniquely determined, and the UE location is the first location. The UE can use the first location and the ephemeris information of the target satellite to calculate the unique open-loop parameter required by the target satellite, i.e., the first compensation parameter TA. B1 and FO B1 The UE can perform RACH-less handover based on the first compensation parameter, for example, by applying the first compensation parameter and sending the first SR to the target satellite on the PUCCH. The UE can start a first timer (T_fallback) to monitor the response on the PDCCH indicating scheduling clearance. If a response is received from the target satellite before the first timer expires, it indicates that the satellite handover was successful or the UE has accessed the target satellite. If the UE does not receive a response from the target satellite when the first timer expires, it indicates that the RACH-less handover has failed, and the UE can immediately fall back to the standard PRACH random access procedure to perform PRACH random access. This allows the UE to achieve satellite handover through PRACH random access.

[0286] Figure 6 This is another schematic flowchart of the satellite handover method provided in the embodiments of this application.

[0287] For example, when the UE obtains the first and second locations using the first model, the satellite handover method provided in this application embodiment can be found in [reference needed]. Figure 6 The embodiment shown. As... Figure 6 As shown, the satellite handover method provided in this application embodiment may include S201, S202, and S601-S604, or may include S201, S202, S601-S603 and S605. The specific implementation principle of S201-S202 can be found in [reference needed]. Figure 2 The specific implementation principle of the illustrated embodiment will not be elaborated here.

[0288] S601, the UE can start the first timer to monitor scheduling clearance on the physical downlink control channel (PDCCH).

[0289] For example, when sending the first SR, the UE can start a first timer. The first timer can be a probe timer (T_probe).

[0290] S602, if the first timer times out and no response is received from the target satellite, the UE may send a second SR to the target satellite. The second compensation parameter for time-frequency pre-compensation used in the second SR is determined based on the second location of the UE (i.e., the terminal device) and the target satellite information. The second location is output by the first model when the beam range information, the altitude of the source satellite, and the synchronization parameters are input into the first model.

[0291] For example, the second compensation parameter may include and .

[0292] If the first timer times out and no response is received from the target satellite, it indicates that the RACH-less handover performed based on the first compensation parameter has failed. In the event of a RACH-less handover failure performed based on the first compensation parameter, the UE can apply the second compensation parameter and send a second SR to the target satellite on the PUCCH.

[0293] For example, if the first timer times out and no response is received from the target satellite, the UE can use the second compensation parameter to perform time-frequency pre-compensation on the second SR to obtain the adjusted transmission timing T2 and the frequency-adjusted second SR. The UE can then transmit the frequency-adjusted second SR to the target satellite via PUCCH at the adjusted transmission timing T2. This can reduce the probability of the target satellite failing to receive the first SR due to transmission delay and frequency shift between the UE and the target satellite, thereby improving the success rate of the UE accessing the target satellite.

[0294] For example, taking T0 as T02, that is, the synchronization time determined by the UE through the latest SSB broadcast by the target satellite as T02, the UE can calculate the second delay compensation TA based on T02 and the calculated time delay compensation TA. B2 Determine the transmission timing T2. For example, the UE can use a lead time for TA. B2 The sending timing is adjusted in a way that means T2 is TA earlier than T02. B2 T2 = T02 - TA B2 The UE can adjust the frequency by an amount of FO. B2 Adjust the frequency of the second SR to obtain the frequency-adjusted second SR.

[0295] The UE can send a frequency-adjusted second SR to the target satellite via PUCCH at time T2, so that the second SR is aligned with the uplink time window of the target satellite when it arrives, thereby improving the success rate of the target satellite receiving the second SR and thus improving the success rate of accessing the target satellite.

[0296] S603, UE can start a second timer to monitor scheduling permission on PDCCH.

[0297] For example, the UE can start a second timer when sending a second SR. The second timer can also be a fallback timer (T_fallback). Optionally, the second timer can also be a probe timer (T_probe). The duration of the second timer can be the same as or different from the duration of the first timer.

[0298] S604. Before the second timer expires, the target satellite may return a response to the UE upon receiving the second SR. Correspondingly, before the second timer expires, the UE may receive a response from the target satellite. The response indicates that the satellite handover was successful.

[0299] For example, before the second timer expires, the target satellite can return a response to the UE via PDCCH upon receiving the second SR. Correspondingly, the UE can monitor the response returned by the target satellite via PDCCH, which indicates that the satellite handover was successful.

[0300] This facilitates satellite communication for the UE through the NTN network where the target satellite is located.

[0301] S605. If the second timer expires and no response is received from the target satellite, the UE may fall back to the PRACH random access procedure.

[0302] For example, if the second timer expires and the UE does not detect a response from the target satellite via PDCCH, it could indicate a satellite handover failure or a RACH-less handover failure performed based on the second compensation parameters. The UE can then fall back to the PRACH random access procedure.

[0303] This makes it easier for the UE to access the target satellite through the PRACH random access procedure, so as to achieve satellite handover.

[0304] like Figure 6 As shown in the satellite handover method provided in this application embodiment, when the candidate location set S_valid determined by the terminal device (i.e., UE) using the first model contains only two solutions P1 (i.e., the first location) and P2 (i.e., the second location), the UE location is fuzzy or uncertain. The UE location may be the first location or the second location. The UE can use the first location, the second location, and the ephemeris information of the target satellite to calculate two sets of compensation parameters corresponding to the target satellite, namely the first compensation parameter and the second compensation parameter. Both the first compensation parameter and the second compensation parameter are open-loop parameters. The second compensation parameter may include... and When the UE's location is ambiguous or uncertain, the UE can perform sequential RACH-less detection to improve the satellite handover success rate. For example, the UE can perform a RACH-less handover based on a first compensation parameter. A successful RACH-less handover based on the first compensation parameter indicates that the UE's location is the first location or confirms that the UE's location is the first location. A failed RACH-less handover based on the first compensation parameter indicates that the UE's location is not the first location or confirms that the UE's location is not the first location. In the case of a failed RACH-less handover based on the first compensation parameter, the UE can perform a RACH-less handover based on a second compensation parameter. When performing a RACH-less handover based on the second compensation parameter, for example, the UE can apply the second compensation parameter to send a second SR to the target satellite on the PUCCH. The UE can start a second timer (T_fallback) to monitor the response on the PDCCH indicating scheduling permission. If a response is received from the target satellite before the second timer expires, it indicates that the satellite handover was successful or that the UE has accessed the target satellite, and it can also indicate that the UE's location is the second location or confirms that the UE's location is the second location. If the UE does not receive a response from the target satellite when the second timer expires, it indicates that the RACH-less handover has failed. The UE can immediately fall back to the standard PRACH random access procedure to perform PRACH random access, so that the UE can achieve satellite handover through PRACH random access.

[0305] In the satellite handover method provided in this application, the terminal device (i.e., UE) can operate without relying on VSAT hardware (such as a compass, inclinometer, or directional antenna), but only on the TA and FO closed-loop information that all UEs (including handheld terminals) possess. This enables broad support for traditional terminals.

[0306] The solution provided in this application obtains UE location and other parameters through geometric calculations rather than real-time measurement of target satellite signals (such as the SSB signal of the target satellite). Therefore, the solution provided in this application does not require beam overlap between two satellites. The solution provided in this application is applicable to soft handover and hard handover scenarios with coverage gaps.

[0307] To address the potential ambiguity of dual solutions in geometric solutions, embodiments of this application provide a satellite switching method employing a sequential RACH-less detection mechanism, such as... Figure 6 The illustrated embodiment solves the location uncertainty problem by using time-based, multi-attempt attempts without increasing signaling overhead.

[0308] This application provides the entire process of satellite handover method, including geometric calculation, sequential detection and / or backoff, which can be implemented internally by the UE. It mainly utilizes the existing RRC and MAC layer mechanisms, requiring minimal modification to the protocol, only the addition of beam range information in SIB19 is needed.

[0309] Since the satellite handover method provided in this application has the characteristics of not relying on GNSS positioning and supporting hard handover, the satellite handover method provided in this application is not only applicable to standard 5G NTN continuous coverage scenarios, GNSS denial scenarios, and satellite beam discontinuous coverage scenarios, but also applicable to emergency disaster relief and temporary networking scenarios, terminal equipment in sensitive environments subject to interference, and low-cost and / or low-power Internet of Things (IoT) terminals.

[0310] Low-cost and / or low-power Internet of Things (IoT) terminals can be a large number of widely distributed IoT devices, such as container monitors, field environment sensors, and smart agriculture monitoring equipment. Due to cost and power considerations, low-cost and / or low-power IoT terminals may not be equipped with high-precision GNSS modules, or may have their GNSS function disabled for extended periods to save power. This application provides a satellite switching method that utilizes the parameters (TA and FO) of the communication link itself for assisted positioning and switching, enabling low-cost and / or low-power IoT terminals to maintain satellite connectivity even without GPS assistance, thus lowering the barrier to entry for terminal device hardware configuration. Low-cost and / or low-power IoT terminals can be referred to as dumb terminals or minimally invasive terminals.

[0311] In sensitive environments subject to interference, such as industrial parks with strong electromagnetic interference, or geographical areas with targeted GPS spoofing or interference, traditional handover mechanisms relying on GNSS positioning become completely ineffective. The satellite handover method provided in this application can serve as an independent backup handover mechanism for terminal devices in sensitive environments subject to interference. This allows terminal devices in such environments to complete handover solely based on communication signal characteristics (such as closed-loop synchronization parameters in RRC connected state), greatly enhancing the survivability and resilience of the communication system in harsh electromagnetic environments.

[0312] Scenarios with discontinuous satellite beam coverage: For example, in the early stages of building a low-Earth orbit satellite constellation (such as LEO satellites), the insufficient number of satellites leads to gaps in ground coverage. Alternatively, when satellites pass over oceans, polar regions, or other areas, discontinuous beam scheduling may be used to conserve energy. Terminal devices requiring soft handover (overlapping beams of two satellites) cannot handle coverage interruptions. This application provides a satellite handover method that supports hard handover. Even if the UE enters a signal-free gap, as long as the UE has saved constraint parameters (such as parameters from the first model) during the previous satellite's service period, it can estimate the access parameters of the next satellite (even if it hasn't arrived yet) and quickly access the network when the next satellite appears. Therefore, the satellite handover method provided in this application is also applicable to satellite networks with discontinuous coverage.

[0313] In GNSS denial scenarios, such as urban canyons or deeply obscured areas, the number of visible satellites is low, and GNSS signals may not be able to lock onto the target location; for example, the GNSS signal may not be usable for position calculation. However, communication satellites, due to their higher elevation angles, may still provide signals. Even when the UE cannot obtain three-dimensional coordinate positioning, it can still maintain communication service continuity by employing the satellite handover method provided in this application, using the TA and FO characteristics of a single satellite. These communication satellites include, for example, those in an NTN (Network Telecommunication Network).

[0314] In emergency disaster relief and temporary network deployment scenarios, such as when ground base stations are damaged due to earthquakes or floods and communication needs to be quickly restored via satellite, this application provides a satellite handover method applicable to ordinary terminals without additional directional antennas or professional satellite communication peripherals. Ordinary handheld mobile phones (such as non-professional satellite phones) used by people in disaster areas can employ this satellite handover method when accessing the network via NTN, enabling smooth switching between high-speed moving low-Earth orbit satellites and ensuring the continuity of lifelines.

[0315] This application provides a communication system, which includes a source satellite, a target satellite, and a terminal device.

[0316] The source satellite can be used to broadcast a first signal, which includes the source satellite's beam range information and the target satellite's information.

[0317] The terminal device can be used to receive a first signal from a source satellite and to send a first scheduling request (SR) to a target satellite. The SR is used for satellite handover. The first compensation parameter for time-frequency pre-compensation of the first SR is determined based on the first position of the terminal device and the target satellite information. The first position is output by the first model when the beam range information, the altitude of the source satellite, and the latest received synchronization parameters from the source satellite are input into the first model. The first model is constructed from equal time delay circles, equal Doppler lines, and beam range circles.

[0318] Optionally, the target satellite can be used to send a response to the terminal device upon receiving the first SR, the response indicating that the satellite handover was successful.

[0319] Optionally, the terminal device can also be used to start the first timer.

[0320] If the first timer times out and no response is received from the target satellite, the terminal device can also be used to send a second time-frequency pre-compensation (SR) to the target satellite. The second compensation parameter used for the second SR is determined based on the second position of the terminal device and the target satellite information. The second position is output by the first model when the beam range information, the altitude of the source satellite, and the synchronization parameters are input into the first model.

[0321] Optionally, the target satellite can also be used to send a response to the terminal device upon receiving a second SR, the response indicating that the satellite handover was successful.

[0322] This application provides a communication system, which includes a satellite and a terminal device. The satellite in the communication system may include the source satellite and the target satellite described in the above embodiments.

[0323] This application provides a satellite, including a processor and a memory. The memory stores computer-executable instructions. The processor executes the computer-executable instructions stored in the memory, causing the satellite to perform the satellite switching method described above. The satellite can be a source satellite or a target satellite.

[0324] It should be noted that the module names involved in the embodiments of this application can all be defined as other names, as long as they can achieve the function of each module, and no specific restrictions are placed on the module names.

[0325] The satellite handover method according to the embodiments of this application has been described above. The apparatus for performing the above method provided in the embodiments of this application is described below. Those skilled in the art will understand that the methods and apparatus can be combined with and referenced by each other, and the related apparatus provided in the embodiments of this application can perform the steps in the above satellite handover method.

[0326] The satellite handover method provided in this application can be applied to electronic devices with communication functions. The electronic devices include terminal devices, and the specific device form of the terminal devices can be referred to the above-mentioned descriptions, which will not be repeated here.

[0327] This application provides a terminal device, which includes a processor and a memory; the memory stores computer execution instructions; the processor executes the computer execution instructions stored in the memory, causing the terminal device to perform the above-described method.

[0328] This application provides a chip. The chip includes a processor, which is used to call a computer program in memory to execute the technical solutions in the above embodiments. Its implementation principle and technical effects are similar to those in the related embodiments described above, and will not be repeated here.

[0329] This application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, it implements the methods described above. The methods described in the above embodiments can be implemented wholly or partially by software, hardware, firmware, or any combination thereof. If implemented in software, the functionality can be stored as one or more instructions or code on or transmitted over the computer-readable medium. The computer-readable medium can include computer storage media and communication media, and can also include any medium that can transfer a computer program from one place to another. The storage medium can be any target medium accessible by a computer.

[0330] In one possible implementation, a computer-readable medium may include RAM, ROM, compact disc read-only memory (CD-ROM) or other optical disc storage, disk storage or other magnetic storage devices, or any other medium targeted to carry or to store the required program code in the form of instructions or data structures, and accessible by a computer. Furthermore, any connection is appropriately referred to as a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. As used herein, disks and optical discs include laser discs, Digital Versatile Discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, while optical discs optically reproduce data using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0331] This application provides a computer program product, which includes a computer program that, when run, causes the computer to perform the above-described method.

[0332] This application describes embodiments of methods, apparatus (systems), and computer program products according to embodiments of this application with reference to flowchart illustrations and / or block diagrams. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processing unit of a general-purpose computer, special-purpose computer, embedded processor, or other programmable device to produce a machine, such that the instructions, which execute via the processing unit of the computer or other programmable data processing device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0333] The above detailed embodiments further illustrate the purpose, technical solution, and beneficial effects of the embodiments of this application. It should be understood that the above are merely specific embodiments of the embodiments of this application and are not intended to limit the protection scope of the embodiments of this application. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solutions of the embodiments of this application should be included within the protection scope of the embodiments of this application.

Claims

1. A satellite handover method, characterized by, Applied to a terminal device, the method includes: Receive a first signal from a source satellite, the first signal including the beam range information of the source satellite and the target satellite information; A first scheduling request (SR) is sent to the target satellite. The SR is used for satellite handover. The first compensation parameter for time-frequency pre-compensation of the first SR is determined based on the first position of the terminal device and the target satellite information. The first position is output by the first model when the beam range information, the altitude of the source satellite and the latest received synchronization parameters from the source satellite are input into the first model. The first model is constructed from equal delay circles, equal Doppler lines and beam range circles. The source satellite's beam range information includes the source satellite's beam radius, and the synchronization parameters include a first time advance (TA) and a first frequency offset (FO). The first position is the intersection of the first equal time delay circle and the first equal Doppler line, and the first position is located within the first beam range circle; Wherein, the first equal time delay circle is determined based on the first TA and the altitude of the source satellite; the first equal Doppler line is determined based on the first FO, the flight direction and velocity of the source satellite; and the radius of the first beam range circle is the beam radius.

2. The method of claim 1, wherein, The method further includes: Start the first timer; Before the first timer expires, a response is received from the target satellite, which indicates that the satellite handover was successful.

3. The method according to claim 1, characterized in that, The method further includes: Start the first timer; If the first timer expires and no response is received from the target satellite, the process falls back to the Physical Random Access Channel (PRACH) random access procedure.

4. The method according to claim 1, characterized in that, The method further includes: Start the first timer; If the first timer times out and no response is received from the target satellite, a second SR is sent to the target satellite. The second compensation parameter for the time-frequency pre-compensation of the second SR is determined based on the second location of the terminal device and the target satellite information. The second location is output by the first model when the beam range information, the altitude of the source satellite and the synchronization parameters are input into the first model.

5. The method according to claim 4, characterized in that, The method further includes: Start the second timer; Before the second timer expires, a response is received from the target satellite, which indicates that the satellite handover was successful.

6. The method according to claim 4, characterized in that, The method further includes: Start the second timer; If the second timer times out and no response is received from the target satellite, the process falls back to the PRACH random access procedure.

7. The method according to claim 1, characterized in that, The beam range information of the source satellite also includes the beam center position of the source satellite. In a coordinate system with the center of the first equal-delay circle as the origin and the flight direction of the source satellite as the positive X-axis, the beam center position of the source satellite is: The coordinates of the first position are the first coordinates (x1, y1, 0), and the first coordinates satisfy the formula: in, Let be the radius of the first equal-delay circle. , For the first TA, This indicates the common delay compensation of the source satellite. The altitude of the source satellite, , c is the speed of light. , The carrier frequency of the source satellite. This indicates the common frequency compensation of the source satellite. For the first FO, The velocity or flight speed of the source satellite. The beam radius is given.

8. The method according to claim 7, characterized in that, The target satellite information includes the target satellite's position information and its flight speed. and the carrier frequency of the target satellite The first compensation parameter includes a first time delay compensation. and the first frequency pre-compensation value ; Satisfying the formula: Satisfying the formula: Satisfying the formula: in, This indicates the distance between the first location and the target satellite. At the speed of light, The flight speed of the target satellite Decomposition amount in the X-axis direction, The flight speed of the target satellite Decomposition in the Y-axis direction, Let be the value of the target satellite's position in the X-axis direction. The value of the target satellite's position in the Y-axis direction. The position of the target satellite in the Z-axis direction is the value of the target satellite's position or the target satellite's altitude. , , The location is determined based on the position information of the target satellite.

9. The method according to claim 4, characterized in that, The source satellite's beam range information includes the source satellite's beam radius, and the synchronization parameters include a first time advance (TA) and a first frequency offset (FO). The second position is the intersection of the first equal time delay circle and the first equal Doppler line, and the second position is located within the first beam range circle; Wherein, the first equal time delay circle is determined based on the first TA and the altitude of the source satellite; the first equal Doppler line is determined based on the first FO, the flight direction and velocity of the source satellite; and the radius of the first beam range circle is the beam radius.

10. The method according to claim 9, characterized in that, The beam range information of the source satellite also includes the beam center position of the source satellite. In a coordinate system with the center of the first equal-delay circle as the origin and the flight direction of the source satellite as the positive X-axis, the beam center position of the source satellite is: The coordinates of the second position are the second coordinates (x2, y2, 0), and the second coordinates satisfy the formula: in, Let be the radius of the first equal-delay circle. , For the first TA, This indicates the common delay compensation of the source satellite. The altitude of the source satellite, , c is the speed of light. , The carrier frequency of the source satellite. This indicates the common frequency compensation of the source satellite. For the first FO, The velocity or flight speed of the source satellite. The beam radius is given.

11. The method according to claim 10, characterized in that, The target satellite information includes the target satellite's position information and its flight speed. and the carrier frequency of the target satellite The second compensation parameter includes a second time delay compensation. Second frequency pre-compensation value ; Satisfying the formula: Satisfying the formula: Satisfying the formula: in, This indicates the distance between the second location and the target satellite. At the speed of light, The flight speed of the target satellite Decomposition amount in the X-axis direction, The flight speed of the target satellite Decomposition in the Y-axis direction, Let be the value of the target satellite's position in the X-axis direction. The value of the target satellite's position in the Y-axis direction. The position of the target satellite in the Z-axis direction is the value of the target satellite's position or the target satellite's altitude. , , The location is determined based on the position information of the target satellite.

12. The method according to claim 1, characterized in that, The first signal is system information block type 19, in which the beam range information of the source satellite and the target satellite information are carried.

13. The method according to any one of claims 1-12, characterized in that, The first signal also includes a service termination time, which is the time when the source satellite stops serving the geographical area where the terminal device is located, or the time when the source satellite stops providing services to the terminal device.

14. The method according to claim 13, characterized in that, The target satellite information includes the ephemeris information of the target satellite, the carrier frequency of the target satellite, and the time when the target satellite begins to serve the geographical area where the terminal device is located.

15. The method according to any one of claims 1-12, characterized in that, The synchronization parameters are closed-loop synchronization parameters.

16. The method according to any one of claims 1-12, characterized in that, The first SR is transmitted via the Physical Uplink Control Channel (PUCCH) of the target satellite.

17. The method according to claim 2, characterized in that, The response was received via the physical downlink control channel (PDCCH) of the target satellite.

18. A satellite handover method, characterized in that, Applied to a source satellite, the method includes: A first signal is broadcast to a terminal device. The first signal includes the beam range information of the source satellite and the target satellite information. The first signal is used to determine a first compensation parameter. The first compensation parameter is used for time-frequency pre-compensation of the first scheduling request (SR) sent by the terminal device to the target satellite. The SR is used for satellite handover. The first compensation parameter is determined based on the first position of the terminal device and the target satellite information. The first position is output by the first model when the terminal device inputs the beam range information, the altitude of the source satellite, and the latest synchronization parameters received from the source satellite into the first model. The first model is constructed from equal delay circles, equal Doppler lines, and beam range circles. The source satellite's beam range information includes the source satellite's beam radius, and the synchronization parameters include a first time advance (TA) and a first frequency offset (FO). The first position is the intersection of the first equal time delay circle and the first equal Doppler line, and the first position is located within the first beam range circle; Wherein, the first equal time delay circle is determined based on the first TA and the altitude of the source satellite; the first equal Doppler line is determined based on the first FO, the flight direction and velocity of the source satellite; and the radius of the first beam range circle is the beam radius.

19. The method according to claim 18, characterized in that, The beam range information of the source satellite also includes the beam center position of the source satellite.

20. A satellite handover method, characterized in that, Applied to a target satellite, the method includes: A scheduling request (SR) is received from a terminal device. The SR is used for satellite handover. The compensation parameters for the time-frequency pre-compensation of the SR are determined by the terminal device based on its position and the target satellite information received from the source satellite. The position of the terminal device is output by the first model when the terminal device inputs the beam range information from the source satellite, the altitude of the source satellite, and the latest received synchronization parameters from the source satellite into the first model. The first model is constructed from an equal-delay circle, an equal-Doppler line, and a beam range circle. The beam range information of the source satellite includes the beam radius of the source satellite. The synchronization parameters include a first time advance (TA) and a first frequency offset (FO). The position of the terminal device is the intersection of the first equal-delay circle and the first equal-Doppler line, and the position of the terminal device is located within the first beam range circle. The first equal-delay circle is determined based on the first TA and the altitude of the source satellite. The first equal-Doppler line is determined based on the first FO, the flight direction and velocity of the source satellite. The radius of the first beam range circle is the beam radius. A response is sent to the terminal device, the response indicating that the satellite handover was successful.

21. The method according to claim 20, characterized in that, The SR is either a first SR or a second SR, the compensation parameter is either a first compensation parameter or a second compensation parameter, and the position of the terminal device is either a first position or a second position; The first compensation parameter is related to the first position, and the first compensation parameter is used for time-frequency pre-compensation of the first SR; The second compensation parameter is related to the second position and is used for time-frequency pre-compensation of the second SR.

22. A communication system, characterized in that, The communication system includes: satellites and terminal equipment; The satellite is used to perform the method as described in any one of claims 18-21, and the terminal device is used to perform the method as described in any one of claims 1-17.

23. A communication system, characterized in that, The communication system includes: a source satellite, a target satellite, and terminal equipment; The source satellite is used to broadcast a first signal, the first signal including the beam range information of the source satellite and the target satellite information; The terminal device is used to receive a first signal from the source satellite and to send a first scheduling request (SR) to the target satellite. The SR is used for satellite switching. The first compensation parameter for time-frequency pre-compensation of the first SR is determined based on the first position of the terminal device and the target satellite information. The first position is output by the first model when the terminal device inputs the beam range information, the altitude of the source satellite, and the latest received synchronization parameters from the source satellite into the first model. The first model is constructed from equal delay circles, equal Doppler lines, and beam range circles. The source satellite's beam range information includes the source satellite's beam radius, and the synchronization parameters include a first time advance (TA) and a first frequency offset (FO). The first position is the intersection of the first equal time delay circle and the first equal Doppler line, and the first position is located within the first beam range circle; Wherein, the first equal time delay circle is determined based on the first TA and the altitude of the source satellite; the first equal Doppler line is determined based on the first FO, the flight direction and velocity of the source satellite; and the radius of the first beam range circle is the beam radius.

24. The communication system according to claim 23, characterized in that, The target satellite is configured to send a response to the terminal device upon receiving the first SR, the response indicating that the satellite handover was successful.

25. A terminal device, characterized in that, include: Processor and memory; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the terminal device to perform the method as described in any one of claims 1-17.

26. A satellite, characterized in that, include: Processor and memory; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the satellite to perform the method as described in any one of claims 18-21.

27. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1-21.

28. A chip system, characterized in that, It includes at least one processor and a communication interface, the communication interface and the at least one processor being interconnected via a line, the at least one processor being configured to run a computer program or instructions to perform the method as described in any one of claims 1-21.

29. A computer program product, characterized in that, Includes a computer program that, when run, causes a computer to perform the method as described in any one of claims 1-21.

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