Doppler frequency shift compensation method and apparatus, and device and storage medium

Abstract

The present application relates to the field of wireless communications. Provided are a Doppler frequency shift compensation method and apparatus, and a device and a storage medium. The method comprises: acquiring ephemeris information of a satellite; on the basis of the ephemeris information and a first frequency shift value which is estimated using a beam position center, compensating for a synchronization signal block (SSB) within a beam position, and sending a pre-compensated SSB to a terminal; and then, on the basis of a second frequency shift value, which has been updated via interpolation, compensating for an uplink signal and a downlink signal within the beam position, and sending a pre-compensated downlink signal to the terminal. A terminal can perform Doppler frequency shift compensation without relying on GNSS location information, thereby reducing the cost and usage power consumption of the terminal, decreasing the number of times that the terminal performs frequency sweeping in an initial access stage, and shortening the latency for the terminal to access a cell.

Description

Doppler shift compensation method, device, equipment and storage medium

[0001] Cross-reference to Related Applications

[0002] This application claims priority to the Chinese patent application No. 2024113762007, filed on September 29, 2024, and entitled “Doppler shift compensation method, device, equipment and storage medium”, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of wireless communication, and provides a Doppler shift compensation method, device, equipment and storage medium. BACKGROUND

[0004] In a satellite communication system of a non-terrestrial network (NTN), due to the high-speed movement of a satellite relative to the ground, the frequency of a signal received by a ground station changes, which is referred to as Doppler shift.

[0005] In order to alleviate the negative effects caused by the Doppler shift, a terminal performs rough Doppler shift compensation through a series of operations such as synchronization raster scanning, primary synchronization signal (PSS) / secondary synchronization signal (SSS) detection, and broadcast physical channel (PBCH) decoding, and then combines Doppler shift compensation based on satellite broadcast ephemeris information and locally obtained global navigation satellite system (GNSS) position information, and Doppler shift compensation based on a demodulation reference signal (DMRS) or other reference signals, to achieve more accurate Doppler shift compensation for a downlink signal.

[0006] The non-terrestrial network protocol standard specifies that the terminal must obtain valid GNSS position information and satellite ephemeris information at the same time to perform Doppler frequency shift compensation, otherwise, the terminal cannot establish network communication with the cell. When the global navigation satellite signal is good, the GNSS module can perform centimeter-level positioning on the terminal. However, in the scenarios of global navigation satellites in medium-high orbits, rainy days, dense jungles, etc., the positioning accuracy and signal strength of the GNSS module will decrease significantly, and the terminal cannot obtain its own GNSS position information in the above application scenarios, resulting in that the terminal cannot complete Doppler frequency shift compensation, and affecting the network communication between the terminal and the cell. Moreover, for low-cost Internet of Things terminals, low-speed mobile or stationary broadband terminals, using the GNSS module will also increase the terminal cost and power consumption.

[0007] The terminal initiates frequency sweeping in the initial cell search process, scans each frequency point on all supported frequency bands, and searches for accessible cells. Due to the Doppler frequency shift in the downlink signal of the satellite-based base station, the frequency point distance of the downlink signal in the frequency band from the preset frequency point of the signal is far, which further causes the terminal to need to scan a very large range of global synchronization channel numbers (GSCN) and a very large number of frequency points. The terminal first attempts to scan the frequency band with a large frequency offset step, and then attempts to scan the frequency band with a small frequency offset step. By evaluating the signal quality of the PSS / SSS received when scanning the frequency point, the terminal selects the cell with the best signal quality to access. Frequent frequency sweeping operations increase the delay of the terminal in the cell search process, and further increase the delay of the terminal in accessing the cell, affecting the network communication of the terminal. SUMMARY

[0008] Embodiments of the present application provide a Doppler frequency shift compensation method, device, equipment and storage medium to solve the problem of compensating the Doppler frequency shift of the downlink signal when the terminal does not install a GNSS module or cannot obtain GNSS position information.

[0009] In a first aspect, embodiments of the present application provide a Doppler frequency shift compensation method, which is applied to a satellite-based base station, and includes:

[0010] Obtaining ephemeris information of a satellite;

[0011] Compensating a synchronization signal block (SSB) within a wave position based on the ephemeris information and a first frequency shift value estimated by a wave center, and sending a pre-compensated SSB to a terminal;

[0012] Compensating an uplink signal and a downlink signal within the wave position based on a second frequency shift value updated by interpolation, and sending a pre-compensated downlink signal to the terminal.

[0013] Optionally, the first frequency shift value of the wave center is estimated in the following way:

[0014] Based on the ephemeris information, a ground projection point of the satellite, a satellite movement direction and a satellite orbit height are obtained.

[0015] Based on the distance between the wave center and the ground projection point and the satellite movement direction, a first included angle between the ground projection point and the satellite movement direction and the wave center is obtained, and based on the distance between the wave center and the ground projection point, a second included angle between the earth center and the current position of the satellite and the wave center is obtained.

[0016] Based on the ephemeris information, the first included angle and the second included angle, Doppler frequency shift estimation is performed on the wave center to obtain the first frequency shift value of the wave center.

[0017] Optionally, the second frequency shift value after interpolation update is obtained in the following way:

[0018] Based on the Doppler frequency shift deviation change rate and the time interval of the SSB period, the first frequency shift value of the wave center is interpolated and updated to obtain the second frequency shift value of the wave center generated in the time interval.

[0019] In a second aspect, the embodiments of the present application further provide a Doppler frequency shift compensation method, which is applied to a terminal and includes:

[0020] Receiving a pre-compensation synchronization signal block (SSB) sent by a first cell, the first cell being a cell whose signal quality meets an evaluation standard;

[0021] Based on the pre-compensation SSB, estimating a basic frequency shift value of the terminal relative to a wave center, the basic frequency shift value being used to compensate for the Doppler frequency shift of a first downlink signal;

[0022] Based on the first downlink signal compensated by the basic frequency shift, compensating for the Doppler frequency shift of a second downlink signal, and based on the pre-compensation downlink signal sent by the first cell, estimating a dynamic frequency shift value generated by the terminal in a time interval of an SSB period, the dynamic frequency shift value being used to compensate for the Doppler frequency shift of the second downlink signal.

[0023] Optionally, the estimating the basic frequency shift value of the terminal relative to the wave center based on the pre-compensation SSB includes:

[0024] Detecting a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) in the pre-compensation SSB;

[0025] receive a first reference signal in a physical broadcast channel (PBCH), a channel position of the PBCH being determined based on a time domain position of the PSS and a frequency domain position of the SSS;

[0026] estimate a first frequency shift value of the beam center based on a phase difference between the received first reference signal and a local first reference signal.

[0027] Optionally, the estimating a dynamic frequency shift value of the terminal in a time interval of the SSB period based on the pre-compensated downlink signal transmitted by the first cell comprises:

[0028] the downlink signal comprises a second reference signal based on the pre-compensated downlink signal transmitted by the first cell, and a dynamic frequency shift value of the terminal relative to the beam center is estimated based on a phase difference between the received second reference signal and a local second reference signal.

[0029] In a third aspect, the embodiments of the present application further provide a Doppler frequency shift compensation device, which is applied to a space-based base station and comprises:

[0030] a first frequency shift compensation unit configured to obtain ephemeris information of a satellite;

[0031] a second frequency shift compensation unit configured to compensate an uplink signal and a downlink signal in a beam based on the second frequency shift value updated by interpolation, and transmit a pre-compensated downlink signal to the terminal.

[0032] a second frequency shift compensation unit configured to compensate an uplink signal and a downlink signal in a beam based on the second frequency shift value updated by interpolation, and transmit a pre-compensated downlink signal to the terminal.

[0033] Optionally, the first frequency shift compensation unit estimates the first frequency shift value of the beam center in the following manner:

[0034] based on the ephemeris information, obtain a ground projection point of the satellite, a satellite motion direction and an orbital height of the satellite;

[0035] based on a distance between the beam center and the ground projection point and the satellite motion direction, obtain a first included angle between the ground projection point and the satellite motion direction and the beam center, and based on the distance between the beam center and the ground projection point, obtain a second included angle between a geocenter and a current position of the satellite and the beam center;

[0036] based on the ephemeris information, the first included angle and the second included angle, perform Doppler frequency shift estimation on the beam center to obtain the first frequency shift value of the beam center.

[0037] Optionally, the second frequency shift compensation unit adopts the following manner to obtain the second frequency shift value after interpolation update:

[0038] The first frequency shift value of the wave position center is interpolated and updated based on the Doppler shift deviation change rate and the time interval of the SSB period, to obtain a second frequency shift value of the wave position center generated in the time interval.

[0039] In a fourth aspect, the embodiments of the present application also provide a Doppler shift compensation device, which is applied to a terminal and includes:

[0040] The base frequency shift compensation unit is configured to receive a pre-compensation synchronization signal block (SSB) sent by a first cell, and the first cell is a cell whose signal quality meets an evaluation standard.

[0041] The base frequency shift compensation unit is configured to estimate a base frequency shift value of the terminal relative to a wave position center based on the pre-compensation SSB, and the base frequency shift value is used to compensate for the Doppler shift of a first downlink signal.

[0042] The dynamic frequency shift compensation unit is configured to compensate for the Doppler shift of a second downlink signal based on the first downlink signal compensated by the base frequency shift compensation, and estimate a dynamic frequency shift value of the terminal generated in a time interval of an SSB period based on a pre-compensation downlink signal sent by the first cell, and the dynamic frequency shift value is used to compensate for the Doppler shift of the second downlink signal.

[0043] Optionally, the base frequency shift compensation unit is configured to:

[0044] Detect a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) in the pre-compensation SSB.

[0045] Receive a first reference signal in a physical broadcast channel (PBCH), and the channel position of the PBCH is determined based on the time domain position of the PSS and the frequency domain position of the SSS.

[0046] Estimate the base frequency shift value of the terminal relative to the wave position center based on the phase difference between the received first reference signal and a local first reference signal.

[0047] Optionally, the dynamic frequency shift compensation unit is configured to:

[0048] The downlink signal acquires a second reference signal based on the pre-compensation downlink signal sent by the first cell, and estimates the dynamic frequency shift value of the terminal relative to the wave position center based on the phase difference between the received second reference signal and a local second reference signal.

[0049] In a fifth aspect, the embodiments of the present application further provide a computer device, comprising a processor and a memory, wherein the memory stores program codes, and the program codes, when executed by the processor, cause the processor to perform the steps of any of the above-mentioned Doppler shift compensation methods.

[0050] In a sixth aspect, the embodiments of the present application further provide a computer-readable storage medium, comprising program codes, and the program codes, when the program product is run on a computer device, are used to cause the computer device to perform the steps of any of the above-mentioned Doppler shift compensation methods.

[0051] The present application has the following beneficial effects:

[0052] The embodiments of the present application provide a Doppler shift compensation method, device, equipment and storage medium, the method is applied to a satellite-based station, comprising: obtaining ephemeris information of a satellite, compensating a synchronization signal block (SSB) in a wave position based on a first frequency shift value estimated based on the ephemeris information and a wave position center, and sending a pre-compensated SSB to a terminal; and compensating uplink signals and downlink signals in the wave position based on a second frequency shift value updated by interpolation, and sending a pre-compensated downlink signal to the terminal.

[0053] The present application provides a Doppler shift compensation method applied to a satellite-based station, because the satellite-based station compensates a large Doppler shift of an SSB in advance based on ephemeris information and a wave position center, and a basic frequency shift value estimated by a terminal changes slowly along with a change of a satellite in a radial direction, the terminal can still estimate a basic frequency shift value of the terminal relative to the wave position center based on a pre-compensated SSB, and compensate a Doppler shift of a downlink signal, reduces a dependence of the terminal on a GNSS in non-terrestrial network communication, reduces terminal cost and power consumption, reduces a frequency scanning number of the terminal in an initial cell search process, and reduces a delay of the terminal in accessing a cell.

[0054] The satellite-based station compensates uplink signals and downlink signals in the wave position based on the second frequency shift value updated by interpolation, and sends a pre-compensated downlink signal to the terminal, so that the terminal compensates a Doppler shift of the downlink signal based on a basic frequency shift value estimated based on a first downlink signal compensated based on the basic frequency shift, and a dynamic frequency shift value estimated based on the pre-compensated downlink signal, offsets a Doppler shift caused by a satellite movement, and realizes that a frequency tracking accuracy of the terminal meets a requirement.

[0055] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the following description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and achieved by the structure particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0056] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0057] FIG. 1A is a logical diagram of Doppler frequency shift compensation of a terminal on a downlink signal according to the related art;

[0058] FIG. 1B is a reference diagram of estimation of Doppler frequency shift by a terminal according to the related art;

[0059] FIG. 2A is a flow diagram of Doppler frequency shift compensation of an uplink and downlink signal by a satellite base station according to an embodiment of the present application;

[0060] FIG. 2B is a logical diagram of Doppler frequency shift compensation of an uplink and downlink signal by a satellite base station according to an embodiment of the present application;

[0061] FIG. 2C is a reference diagram of continuous deployment of multiple wave positions in a cell covered by a satellite according to an embodiment of the present application;

[0062] FIG. 2D is a reference diagram of Doppler frequency shift values of centers of wave positions in a radial direction of satellite movement according to an embodiment of the present application;

[0063] FIG. 2E is a reference diagram of estimation of Doppler frequency shift values of wave position centers according to an embodiment of the present application;

[0064] FIG. 2F is a logical diagram of Doppler frequency shift compensation of a signal of a radio frequency transceiver according to an embodiment of the present application;

[0065] FIG. 3A is a flow diagram of Doppler frequency shift compensation of a downlink signal by a terminal according to an embodiment of the present application;

[0066] FIG. 3B is a logical diagram of Doppler frequency shift compensation of a downlink signal by a terminal according to an embodiment of the present application;

[0067] FIG. 3C is a reference diagram of a position having the largest deviation from a Doppler frequency shift value of a wave position center according to an embodiment of the present application;

[0068] FIG. 3D is a diagram of Doppler frequency shift deviation between a wave position center and a wave position edge according to an embodiment of the present application;

[0069] FIG. 3E is a diagram of variation of Doppler frequency shift deviation values of wave position edges under different wave position widths according to an embodiment of the present application;

[0070] FIG. 4 is a structural diagram of a Doppler frequency shift compensation device for a satellite base station according to an embodiment of the present application;

[0071] Fig. 5 is a structural schematic diagram of a Doppler shift compensation device for a terminal according to an embodiment of the present application;

[0072] Fig. 6 is a structural schematic diagram of a computer device according to an embodiment of the present application;

[0073] Fig. 7 is a structural schematic diagram of a computing device according to an embodiment of the present application. DETAILED DESCRIPTION

[0074] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions of the present application will be described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments described in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the technical solutions of the present application.

[0075] Some terms in the embodiments of the present application are explained below to facilitate understanding by those skilled in the art.

[0076] 1. Non-terrestrial network: refers to a communication network that does not rely on ground infrastructure, but uses air or space platforms such as satellites, high-altitude platforms (such as stratospheric balloons and unmanned aerial vehicles) to provide communication services, which can extend the coverage of traditional ground cellular networks, especially in remote areas, oceans, mountains and other places where it is difficult to lay ground base stations.

[0077] 2. Doppler shift: refers to the change in wave frequency caused by the relative motion between the wave source and the observer. This phenomenon exists in sound waves, light waves, and electromagnetic waves, but is particularly important in wireless communication because it affects the quality of signal reception.

[0078] 3. Satellite: a device located in the orbit of the Earth, used to provide communication services. According to the height of the satellite orbit, satellites can be divided into Low Earth Orbit (LEO), Medium Earth Orbit (MEO), and High Earth Orbit (GEO).

[0079] 4. Satellite-based base station: refers to a communication device installed on a satellite, which is similar to a base station (BS) in a ground cellular network, responsible for demodulating, encoding, decoding, and other processing of signals from ground terminals and transmitting wireless signals.

[0080] 5、Cell (Cell): refers to a geographical area covered by a base station (whether it is a ground base station or a satellite base station). Each cell has a unique identifier (such as Physical Cell ID, PCI), and the base station transmits signals to terminals within the cell through an antenna, including Synchronization Signal Block (SSB), PBCH, reference signals, etc.

[0081] 6、Frequency band: refers to a range of frequencies used for signal transmission in a wireless communication system. Different communication standards and technologies use different frequency bands to avoid mutual interference.

[0082] 7、Frequency point: refers to a specific center frequency within a certain frequency band. Each frequency point represents a carrier used for data transmission. The selection of frequency points determines the communication frequency between terminals and base stations. In a multi-carrier system, multiple frequency points can be used simultaneously to increase the total capacity of the system.

[0083] 8、Ground gateway station: also known as ground station or ground gateway station, is a fixed facility located on the earth's surface, and is a key component of satellite communication systems, used for communication with satellites and transmission of data received by satellites to the ground network, or sending data from the ground network to the satellite.

[0084] The ground gateway station plays a crucial role in the satellite communication system, not only responsible for signal relay and processing, but also providing an interface with the ground network, ensuring efficient operation of the satellite communication system. Through the ground gateway station, satellite communication can be expanded to a global scale, providing various communication services.

[0085] The design idea of the embodiments of the present application is briefly introduced as follows:

[0086] In the satellite communication system of non-terrestrial networks, due to the high-speed movement of satellites relative to the ground, the frequency of signals received by the ground station changes, which is called Doppler shift.

[0087] In order to alleviate the negative effects of Doppler shift, as shown in FIG. 1A, the terminal performs rough Doppler shift compensation through a series of operations such as synchronization raster scanning, PSS / SSS detection, PBCH decoding, and then combines Doppler shift compensation based on satellite broadcast ephemeris information and locally acquired GNSS position information, as well as Doppler shift compensation based on DMRS or other reference signals, to achieve more accurate Doppler shift compensation for downlink signals.

[0088] Currently, the formula for calculating the maximum Doppler shift of the terminal in the non-terrestrial network is: In the formula, c represents the speed of light, Fc represents the transmission frequency of the satellite base station, V represents the orbital velocity vector of the satellite, R represents the radius of the earth, h represents the orbital height of the satellite, γ represents the relative height of the satellite relative to the earth surface, and Fd represents the Doppler shift value of the terminal. In the reference schematic diagram shown in FIG. 1B, S represents a satellite moving in a circular orbit, M represents a terminal, O is the center of the earth, θ represents the included angle between the satellite movement direction and the direction of the terminal, and μ represents the included angle between the terminal and the satellite.

[0089] The non-terrestrial network protocol standard stipulates that the terminal must simultaneously obtain valid GNSS position information and satellite ephemeris information to perform Doppler shift compensation, otherwise, the terminal cannot establish network communication with the satellite. When the global navigation satellite signal is good, the GNSS module can perform centimeter-level positioning on the terminal. However, in the case of a global navigation satellite in a medium-high orbit, a rainy day, dense jungle, etc., the positioning accuracy and signal strength of the GNSS module will decrease significantly, and the terminal cannot obtain its own GNSS position information in the above application scenarios, resulting in the terminal being unable to complete Doppler shift compensation and affecting network communication with the cell. Moreover, for low-cost Internet of Things terminals, low-speed mobile or stationary broadband terminals, using a GNSS module will also increase the terminal cost and power consumption.

[0090] The terminal initiates frequency sweeping in the initial cell search process, scans each frequency point on all supported frequency bands, and searches for accessible cells. Due to the Doppler shift in the downlink signal of the satellite base station, the frequency point distance of the downlink signal in the frequency band from the preset frequency point of the signal is far, which further causes the terminal to need to scan a very large GSCN range and a very large number of frequency points. The terminal first attempts to scan the frequency band with a large frequency offset step, and then attempts to scan the frequency band with a small frequency offset step. By evaluating the signal quality of the PSS / SSS received when scanning the frequency point, the terminal selects the cell with the optimal access signal quality. Frequent frequency sweeping operations increase the delay of the terminal in the cell search process, and further increase the delay of the terminal in accessing the cell, affecting the network communication of the terminal.

[0091] Therefore, the present application proposes a Doppler shift compensation method applied to a satellite base station. The method specifically comprises: obtaining satellite ephemeris information, compensating the synchronization signal block (SSB) in the wave position based on the first frequency shift value estimated based on the ephemeris information and the wave position center, and sending the pre-compensated SSB to the terminal; and based on the second frequency shift value updated by interpolation, compensating the uplink signal and the downlink signal in the wave position, and sending the pre-compensated downlink signal to the terminal.

[0092] ​​​Since the satellite-based base station compensates the Doppler frequency shift of the SSB in advance, the frequency point of the pre-compensation SSB in the frequency band is closer to the preset frequency point of the signal, the terminal scans around the preset frequency point with a smaller frequency offset step, and the pre-compensation SSB can be received, the frequency scanning times of the terminal in the initial cell search process are reduced, and the delay of the terminal accessing the cell is reduced.

[0093] The satellite-based base station compensates the large Doppler frequency shift of the SSB based on the ephemeris information and the wave position center, and the estimated basic frequency shift value of the terminal changes slowly with the change of the satellite movement in the radial direction, so that the terminal can estimate the basic frequency shift value of the terminal relative to the wave position center based on the pre-compensation SSB in the case that the terminal does not install a GNSS module or cannot obtain GNSS position information, and compensate the Doppler frequency shift of the downlink signal, which can offset the Doppler frequency shift caused by the satellite movement, reduces the dependence of the terminal on the GNSS in the non-terrestrial network communication, and reduces the terminal cost and power consumption.

[0094] The satellite-based base station compensates the uplink signal and the downlink signal in the wave position based on the second frequency shift value updated by interpolation, and sends the pre-compensation downlink signal to the terminal, so that the terminal compensates the Doppler frequency shift of the downlink signal based on the dynamic frequency shift value estimated based on the pre-compensation downlink signal, offsets the Doppler frequency shift caused by the satellite movement, and realizes the frequency tracking accuracy of the terminal to meet the requirements.

[0095] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings of the specification, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application, and the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0096] The satellite communication system includes a satellite and a terminal, in order to reduce the negative effects of the Doppler frequency shift, a reliable bidirectional communication connection is established between the satellite and the terminal, the terminal and the satellite respectively compensate the Doppler frequency shift of the uplink and downlink signals, so as to ensure that the satellite can correctly receive the signal sent by the terminal, and the terminal can correctly receive the signal sent by the satellite, and the stability and reliability of the entire satellite communication system are ensured.

[0097] As shown in FIGS. 2A-2B, the satellite-based base station uses the method provided by the present application to realize the Doppler frequency shift compensation of the uplink and downlink signals.

[0098] S201: Obtain the ephemeris information of the satellite.

[0099] The satellite can obtain the ephemeris information and the wave position center from the ground gateway in advance during the movement.

[0100] Ephemeris information describes the satellite orbit position and motion state data, which is crucial for satellite communication systems, GNSS and other satellite-dependent applications. The ephemeris information includes orbit parameters, time parameters and other related information, so that the receiver can accurately calculate the position of the satellite, thereby achieving high-precision positioning and time synchronization.

[0101] In a satellite communication system, in order to improve the capacity, coverage and signal quality of the system, the satellite may need to continuously deploy multiple wave positions in the cell covered by the satellite, and the wave position width of each wave position is the same. When calculating the wave position center position of each wave position, the ground gateway station needs to consider factors such as wave position width, satellite orbit velocity vector, cell diameter, etc.

[0102] As shown in FIG. 2C, the satellite orbit height is 600 km, the satellite orbit velocity vector is 7.56 km / s, the cell diameter in the radial direction of satellite motion is 1000 km, and multiple wave positions are continuously deployed in the radial direction of satellite motion, and the wave position width of each wave position is 25 km. The ground gateway station determines the wave position coverage diameter through the wave position width and the satellite orbit height, determines the number of wave positions required according to the cell diameter and the wave position coverage diameter, calculates the center position of each wave position through geometric method, and obtains the wave position center positions of multiple wave positions in the cell.

[0103] However, considering that the wave position center position will change with the movement of the satellite, the wave position center position is recalculated according to the orbit velocity vector and the orbit parameters of the satellite every time step, and the wave position center position is updated in real time.

[0104] S202: Based on the first frequency shift value estimated based on the ephemeris information and the wave position center, compensate the synchronization signal block (SSB) in the wave position, and send the pre-compensated SSB to the terminal.

[0105] The radial direction refers to the straight-line distance direction between the satellite and the ground terminal, as shown in FIG. 2C, multiple wave positions are continuously deployed in the radial direction of satellite motion, the radial direction of satellite motion is in the same plane as the direction of satellite motion, and the Doppler frequency shift value of the wave position center in the radial direction is the largest among the Doppler frequency shift values in other directions, therefore, the satellite base station of the present application completes the Doppler frequency shift compensation by estimating the Doppler frequency shift of the wave position center. The Doppler frequency shift values of the wave position centers in the radial direction of satellite motion are shown in FIG. 2D, the horizontal axis represents the wave position center, and the vertical axis represents the Doppler frequency shift value. It can be seen that the maximum Doppler frequency shift value of the cell edge wave position is 31.6 KHz.

[0106] The present application combines ephemeris information and wave position center to obtain the formula for calculating the Doppler frequency shift of the wave position center: In the formula, c represents the speed of light, Fc represents the transmission frequency of the satellite-based base station, V represents the orbital velocity vector of the satellite, R represents the radius of the Earth, h represents the orbital height of the satellite, γ represents the relative height of the satellite relative to the surface of the Earth, and Fd' represents the Doppler frequency shift value of the wave position center L'. In the reference schematic diagram shown in FIG. 2E, S represents a satellite moving in a circular orbit, L' represents a wave position center, O is the center of the Earth, a represents a first included angle between a ground projection point and a satellite movement direction, and between the ground projection point and the wave position center, μ represents a second included angle between the center of the Earth and a current position of the satellite, and between the center of the Earth and the wave position center, L represents an intersection between a plane in which the satellite movement direction is located and a ground plane, and θ represents an included angle between velocity components v' and v''.

[0107] The process in which the satellite-based base station uses the above formula to perform Doppler frequency shift estimation is as follows:

[0108] First, based on ephemeris information, a ground projection point of the satellite and a satellite movement direction are obtained.

[0109] Second, based on a distance between the wave position center and the ground projection point and the satellite movement direction, a first included angle between the ground projection point and the satellite movement direction, and between the ground projection point and the wave position center is obtained, and based on the distance between the wave position center and the ground projection point, a second included angle between the center of the Earth and the current position of the satellite, and between the center of the Earth and the wave position center is obtained.

[0110] Finally, the ephemeris information, the first included angle, and the second included angle are substituted into the formula to perform Doppler frequency shift estimation on the wave position center, and a first frequency shift value of the wave position center is obtained.

[0111] Based on the first frequency shift value, a synchronization signal block (SSB) in the wave position is compensated. The SSB is very important to a satellite communication system, and the SSB includes a PSS, an SSS, and a PBCH, and is used to implement frequency synchronization, time synchronization, cell identification, and broadcast of system information.

[0112] S203: Based on the second frequency shift value updated through interpolation, uplink signals and downlink signals in the wave position are compensated, and a pre-compensated downlink signal is sent to a terminal.

[0113] The frequency tracking accuracy of the terminal is controlled to be 0.1 ppm, that is, when the satellite carrier frequency band is an S band (2 GHz), the Doppler frequency shift value needs to be controlled to be within 200 Hz. Therefore, the satellite-based base station of the present application compensates the Doppler frequency shift of the wave position center according to an SSB period, so as to ensure the accuracy of frequency shift estimation of the terminal based on the pre-compensated SSB.

[0114] Further, the SSB period is divided into multiple time intervals, and the first frequency shift value of the wave position center is updated by interpolation based on the Doppler shift deviation rate and the time interval of the SSB period, to obtain a second frequency shift value generated by the wave position center in the time interval. The second frequency shift value will also be reflected in the dynamic frequency shift estimation of the terminal, meeting the Doppler shift tracking accuracy of the terminal within the wave position, and reducing the design complexity of the terminal channel estimation algorithm.

[0115] For example, the Doppler shift deviation rate is 2.7%, the time interval is 100ms, and the first frequency shift value of the wave position center is 1000Hz. Then the second frequency shift value generated by the wave position center in 100ms is (100*2.7%+1000=1002.7, and the second frequency shift value generated by the wave position center in 200ms is (200*2.7%)+1000=1005.4.

[0116] Figure 2F shows a typical signal processing flow of a radio frequency transceiver (RF Transceiver), including signal reception, processing and transmission. The entire process is divided into two parts: the receiving path (RX) and the transmitting path (TX). In the receiving path, the signal undergoes amplification, down-conversion, digitization, Doppler shift compensation and automatic gain control; while in the transmitting path, power amplification, up-conversion, Doppler shift compensation, filtering and inverse fast Fourier transform are performed. The satellite-based base station of the present application combines ephemeris information and wave position center position to estimate the Doppler shift value of the ground wave position center in advance, and pre-compensates the Doppler shift value to the uplink and downlink digital signal processing process.

[0117] However, in the fifth generation new radio (5G New Radio, 5GNR) non-terrestrial network, the uplink carrier frequency points of the frequency division duplex (Frequency Division Duplex, FDD) mode are different, and when calculating the Doppler shift value, the Doppler shift estimation is performed on the uplink and downlink carrier frequency points respectively, and different Doppler shift values are obtained. In the 5GNR non-terrestrial network, the uplink and downlink carrier frequency points of the time division duplex (Time Division Duplex, TDD) mode are the same, and the estimated Doppler shift value can be compensated to the uplink and downlink processing link at the same time.

[0118] As shown in Figures 3A-3B, the terminal uses the method provided by the present application to implement Doppler shift compensation for downlink signals.

[0119] S301: receiving a pre-compensation synchronization signal block SSB sent by a first cell, the first cell being a cell whose signal quality meets the evaluation standard.

[0120] The terminal performs initial cell search in a synchronous raster scanning manner, and takes a cell with optimal signal quality as a first cell.

[0121] In the related art, the terminal initiates frequency sweeping in the initial cell search process, scans each frequency point on all supported frequency bands, and searches for accessible cells. Due to the Doppler shift in the downlink signal of the satellite-based base station, the frequency point of the downlink signal in the frequency band is far away from the preset frequency point of the signal, which further causes the terminal to need to scan a very large GSCN range and a very large number of frequency points. The terminal first attempts to scan the frequency band with a large frequency offset step, and then attempts to scan the frequency band with a small frequency offset step. By evaluating the signal quality of the PSS / SSS received when scanning the frequency point, the terminal selects a cell with optimal access signal quality. The frequent frequency sweeping operation increases the delay of the terminal in the cell search process, and further increases the delay of the terminal in accessing the cell, which affects the network communication of the terminal.

[0122] Since the satellite-based base station of the present application compensates the Doppler shift of the SSB in advance, the frequency point of the pre-compensated SSB in the frequency band is close to the preset frequency point of the signal. The terminal does not need to use a large frequency offset step for frequency sweeping, but can use a small frequency offset step to scan around the preset frequency point to receive the pre-compensated SSB. This reduces the number of frequency sweeping operations of the terminal in the initial cell search process, reduces the signal processing amount when evaluating the cell, reduces the delay of the terminal in accessing the cell, and improves the user experience.

[0123] S302: Based on the pre-compensated SSB, estimate the basic frequency shift value of the terminal relative to the wave position center, which is used to compensate the Doppler shift of the first downlink signal.

[0124] In a wave position, the Doppler shift value of the wave position center is the largest. Although the satellite-based base station compensates the Doppler shift of the SSB based on the first frequency shift value of the wave position center, a certain amount of Doppler shift deviation will still occur when the terminal is not at the wave position center.

[0125] According to the Doppler shift calculation formula, in the wave positions continuously distributed in the radial direction of satellite motion, the maximum Doppler shift deviation from the wave position center will occur at the edge of the wave position in the radial direction of satellite motion, i.e. the gray dot in FIG. 3C. FIG. 3D shows the residual Doppler shift deviation between the wave position center and the wave position edge in the scenarios of wave position width of 25 kilometers and 50 kilometers. When the wave position width is 25 kilometers, the maximum Doppler shift deviation is 1050 Hz, which occurs at the sub-satellite point position (i.e. the gray dot in FIG. 2F); when the wave position width is 50 kilometers, the maximum Doppler shift deviation is 2098 Hz, which occurs at the sub-satellite point position.

[0126] As can be seen from FIG. 3D, the maximum residual Doppler shift deviation is 1 KHz or 2 KHz under different wave bit widths. As can be seen from FIG. 3E, the Doppler shift value of the wave bit edge changes slowly in the radial direction, and the maximum change rate occurs near the sub-satellite point. Therefore, the terminal-based pre-compensation SSB estimated basic frequency shift value will be lower than 1 KHz or 2 KHz, and the basic frequency shift value is continuously compensated in the subsequent uplink and downlink signals to offset the Doppler shift caused by satellite movement, reduce the dependence of the terminal on GNSS in non-terrestrial network communication, and compress the terminal cost and use power consumption.

[0127] The terminal performs the following operations to estimate the basic frequency shift value of the terminal relative to the wave bit center:

[0128] First, the primary synchronization signal (PSS) and the secondary synchronization signal (SSS) in the pre-compensation SSB are detected. The PSS is used for time synchronization with the first cell, and the SSS is used for frequency synchronization with the first cell.

[0129] Second, a first reference signal is received in the physical broadcast channel (PBCH). The channel position of the PBCH is determined based on the time domain position of the PSS and the frequency domain position of the SSS.

[0130] The first reference signal can be a demodulation reference signal (DMRS), a tracking reference signal (TRS), or other reference signals. The DMRS is used for channel estimation in the data demodulation process, and the TRS is used for channel estimation and time / frequency synchronization in the connected state, especially in high-speed mobile scenarios.

[0131] Finally, based on the phase difference between the received first reference signal and the local first reference signal, the basic frequency shift value of the terminal relative to the wave bit center is estimated.

[0132] The terminal compensates the Doppler shift of the first downlink signal based on the basic frequency shift value. After completing the basic frequency shift estimation, the terminal accesses the first cell and formally establishes a connection with the first cell.

[0133] S303: Compensate the Doppler shift of the second downlink signal based on the first downlink signal compensated by the basic frequency shift, and estimate the dynamic frequency shift value generated by the terminal within the time interval of the SSB period based on the pre-compensation downlink signal sent by the first cell. The dynamic frequency shift value is used to compensate the Doppler shift of the second downlink signal.

[0134] The terminal performs the following operations to estimate the dynamic frequency shift value generated by the terminal within the time interval of the SSB period:

[0135] Based on the pre-compensated downlink signal sent by the first cell, a second reference signal is obtained, and based on the phase difference between the second received reference signal and the local second reference signal, a dynamic frequency shift value of the terminal relative to the wave position center is estimated. Wherein, the pre-compensated downlink signal is a physical downlink control channel (PDCCH) or a physical downlink shared channel (PDSCH), and the second reference signal can be a DMRS, a TRS or other reference signals.

[0136] As shown in formula F d (Terminal) = F d (Base) + F d (Dynamic), the terminal obtains the base frequency shift value by processing the first downlink signal compensated by the base frequency shift, compensates the Doppler frequency shift of the second downlink signal based on the base frequency shift value, and compensates the Doppler frequency shift of the second downlink signal based on the dynamic frequency shift value estimated based on the pre-compensated downlink signal, to offset the Doppler frequency shift caused by satellite movement. In the case of not increasing the GNSS module or not being able to obtain the GNSS position information, the downlink signal can still be compensated for the Doppler frequency shift to meet the frequency tracking accuracy.

[0137] Therefore, the idle state terminal of the non-terrestrial network does not need to wait to obtain the ephemeris information and the GNSS position information, the pre-wakeup time of the terminal is omitted, the terminal power consumption is reduced, and the step of re-estimating the Doppler frequency shift during the pre-synchronization after waking up the idle state terminal is also omitted, further reducing the system power consumption. The connected state terminal of the non-terrestrial network reduces the periodic ephemeris calculation and GNSS position update operation, reducing the terminal power consumption. For the terminal initiating reselection and handover in the non-terrestrial network, the ephemeris information of the neighboring area also does not need to be obtained, the time delay in the reselection and handover process is shortened, the system overhead is reduced, and the user experience is effectively improved.

[0138] When the method proposed in the present application is used to compensate the Doppler frequency shift of the low-speed or stationary broadband terminal and the low-cost Internet of Things terminal in the non-terrestrial network, the GNSS position information does not need to be obtained, the dependence of the terminal on external GNSS devices is reduced, and the terminal cost is reduced. However, for high-speed mobile terminals, the present application also compatible with GNSS position information to obtain the terminal moving speed, thereby compensating the Doppler frequency shift caused by the terminal itself.

[0139] Based on the same inventive concept as the above method embodiment, the present embodiment also provides a Doppler frequency shift compensation device applied to a satellite-based base station. As shown in FIG. 4, the Doppler frequency shift compensation device 400 can include:

[0140] The first frequency shift compensation unit 401 is configured to obtain the ephemeris information of the satellite;

[0141] compensate a synchronization signal block (SSB) in a wave position based on the ephemeris information and the first frequency shift value estimated for the wave position center, and send the pre-compensated SSB to the terminal;

[0142] The second frequency shift compensation unit 402 is configured to compensate uplink signals and downlink signals in the wave position based on the second frequency shift value updated by interpolation, and send pre-compensated downlink signals to the terminal.

[0143] Optionally, the first frequency shift compensation unit 401 estimates the first frequency shift value of the wave position center in the following manner:

[0144] Based on the ephemeris information, obtain the ground projection point of the satellite, the satellite motion direction and the satellite orbital height;

[0145] Based on the distance between the wave position center and the ground projection point and the satellite motion direction, obtain the first included angle between the ground projection point and the satellite motion direction and the wave position center, and based on the distance between the wave position center and the ground projection point, obtain the second included angle between the geocenter and the current position of the satellite and the wave position center;

[0146] Based on the ephemeris information, the first included angle and the second included angle, perform Doppler frequency shift estimation on the wave position center to obtain the first frequency shift value of the wave position center.

[0147] Optionally, the second frequency shift compensation unit 402 obtains the second frequency shift value updated by interpolation in the following manner:

[0148] Based on the Doppler frequency shift deviation change rate and the time interval of the SSB period, the first frequency shift value of the wave position center is updated by interpolation to obtain the second frequency shift value of the wave position center generated in the time interval.

[0149] Based on the same inventive concept as the above method embodiments, the embodiments of the present application also provide a Doppler frequency shift compensation device applied to a terminal. As shown in FIG. 5, the Doppler frequency shift compensation device 500 can include:

[0150] The basic frequency shift compensation unit 501 is configured to receive pre-compensated synchronization signal blocks (SSBs) sent by a first cell, and the first cell is a cell whose signal quality meets the evaluation criteria;

[0151] Based on the pre-compensated SSBs, estimate the basic frequency shift value of the terminal relative to the wave position center, and the basic frequency shift value is used to compensate the Doppler frequency shift of the first downlink signal;

[0152] The dynamic frequency shift compensation unit 502 is configured to compensate the Doppler frequency shift of the second downlink signal based on the first downlink signal compensated by the basic frequency shift compensation, and estimate a dynamic frequency shift value generated by the terminal in a time interval of a SSB cycle based on the pre-compensated downlink signal sent by the first cell, the dynamic frequency shift value being used to compensate the Doppler frequency shift of the second downlink signal.

[0153] Optionally, the basic frequency shift compensation unit 501 is configured to:

[0154] detect a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) in the pre-compensated SSB;

[0155] receive a first reference signal in a physical broadcast channel (PBCH), a channel position of the PBCH being determined based on a time domain position of the PSS and a frequency domain position of the SSS;

[0156] estimate a basic frequency shift value of the terminal relative to a wave position center based on a phase difference between the received first reference signal and a local first reference signal.

[0157] Optionally, the dynamic frequency shift compensation unit 502 is configured to:

[0158] The downlink signal acquires a second reference signal based on the pre-compensated downlink signal sent by the first cell, and estimates a dynamic frequency shift value of the terminal relative to the wave position center based on a phase difference between the received second reference signal and a local second reference signal.

[0159] For the convenience of description, the above parts are respectively described as modules (or units) according to functions. Of course, the functions of the modules (or units) can be implemented in the same or multiple software or hardware in the implementation of the present application.

[0160] After introducing the Doppler frequency shift compensation method and device of the exemplary embodiment of the present application, next, the computer device according to another exemplary embodiment of the present application is introduced.

[0161] Those skilled in the art can understand that each aspect of the present application can be implemented as a system, a method or a program product. Therefore, each aspect of the present application can be specifically implemented as follows: a complete hardware embodiment, a complete software embodiment (including firmware, microcode, etc.), or an embodiment combining hardware and software, which can be collectively referred to as "circuitry", "module" or "system".

[0162] Based on the same inventive concept as the method embodiments described above, the embodiments of the present application also provide a computer device. Referring to FIG. 6, the computer device 600 can include at least a processor 601 and a memory 602. The memory 602 stores program codes, which, when executed by the processor 601, cause the processor 601 to perform the steps of any of the Doppler shift compensation methods described above.

[0163] In some possible implementations, the computing device according to the present application can include at least one processor and at least one memory. The memory stores program codes, which, when executed by the processor, cause the processor to perform the steps of the Doppler shift compensation methods according to various exemplary embodiments of the present application described above. For example, the processor can perform the steps shown in FIG. 2A or 3A.

[0164] The computing device 700 according to this embodiment of the present application is described below with reference to FIG. 5. The computing device 700 of FIG. 7 is merely an example and should not impose any limitation on the functions and use range of the embodiments of the present application.

[0165] As shown in FIG. 7, the computing device 700 is in the form of a general-purpose computing device. The components of the computing device 700 can include, but are not limited to, the at least one processing unit 701 described above, the at least one storage unit 702 described above, and a bus 703 connecting different system components, including the storage unit 702 and the processing unit 701.

[0166] The bus 703 represents one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, a processor or local bus using any of a variety of bus architectures.

[0167] The storage unit 702 can include a readable medium in the form of volatile memory, such as a random access memory (RAM) 7021 and / or a cache memory 7022, and can further include a read-only memory (ROM) 7023.

[0168] The storage unit 702 can also include a program / utility 7025 having a set of program modules 7024, including but not limited to an operating system, one or more application programs, other program modules, and program data, each of which or a combination thereof can include implementation of a network environment.

[0169] The computing device 700 can also be communicably coupled to one or more devices 704 (e.g., a keyboard, a pointing device, etc.) that enables a user to interact with the computing device 700 and / or one or more devices that enable a user to interact with the computing device 700 and / or any devices (e.g., a router, a modem, a peer device etc.) that enables the computing device 700 to communicate with one or more other computing devices. Such communication can occur via Input / Output (I / O) interface(s) 705. Still yet, the computing device 700 can communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or the Internet) via network adapter 706. As illustrated, network adapter 706 communicates with the other components of the computing device 700 via bus 703. It should be appreciated that although not shown, other hardware and / or software modules that can be used in conjunction with the computing device 700 can also be utilized, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data archival storage systems, etc.

[0170] Based on the same inventive concept as the method embodiments described above, each aspect of the Doppler shift compensation method provided in the present application can also be implemented in the form of a program product, which includes program codes for causing a computer device to perform the steps of the Doppler shift compensation method according to various exemplary embodiments of the present application described above in the specification when the program product is run on the computer device, for example, the steps shown in FIG. 2A or 3A.

[0171] The program product can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium, for example, can be, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or apparatus, or any combination of the above. More specific examples (a non-exhaustive list) of the readable storage medium include an electrical connection having one or more wires, a portable disc, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0172] Although preferred embodiments of the application have been described, those skilled in the art will recognize that additional modifications and changes can be made thereto without departing from the scope of the present application. Accordingly, the appended claims are intended to cover all such modifications and changes as fall within the scope of the application.

[0173] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A Doppler shift compensation method, applied to a satellite base station, comprising: obtaining ephemeris information of a satellite; compensating a synchronization signal block (SSB) in a wave position based on a first frequency shift value estimated based on the ephemeris information and a wave position center, and sending a pre-compensated SSB to a terminal; compensating an uplink signal and a downlink signal in the wave position based on a second frequency shift value updated by interpolation, and sending a pre-compensated downlink signal to the terminal.

2. The method of claim 1, wherein, The first frequency shift value of the wave position center is estimated in the following way: based on the ephemeris information, obtaining a ground projection point of the satellite, a satellite movement direction and a satellite orbit height; based on the distance between the wave position center and the ground projection point and the satellite movement direction, obtaining a first included angle between the ground projection point and the satellite movement direction, and between the ground projection point and the wave position center, and based on the distance between the wave position center and the ground projection point, obtaining a second included angle between the earth center and the current position of the satellite, and between the earth center and the wave position center; based on the ephemeris information, the first included angle and the second included angle, performing Doppler shift estimation on the wave position center to obtain the first frequency shift value of the wave position center.

3. The method of claim 1, wherein, The second frequency shift value updated by interpolation is obtained in the following way: based on a Doppler shift deviation change rate and a time interval of an SSB period, interpolating and updating the first frequency shift value of the wave position center to obtain a second frequency shift value generated by the wave position center in the time interval. 4.A Doppler shift compensation method, applied to a terminal, comprising: receiving a pre-compensated synchronization signal block (SSB) sent by a first cell, the first cell being a cell whose signal quality meets an evaluation criterion; based on the pre-compensated SSB, estimating a basic frequency shift value of the terminal relative to a wave position center, the basic frequency shift value being used to compensate the Doppler shift of a first downlink signal; based on the first downlink signal compensated by the basic frequency shift, compensating the Doppler shift of a second downlink signal, and based on a pre-compensated downlink signal sent by the first cell, estimating a dynamic frequency shift value generated by the terminal in a time interval of an SSB period, the dynamic frequency shift value being used to compensate the Doppler shift of the second downlink signal.

5. The method of claim 4, wherein, The estimation of the basic frequency shift value of the terminal relative to the wave position center based on the pre-compensated SSB comprises: detecting a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) in the pre-compensated SSB; receiving a first reference signal in a physical broadcast channel (PBCH), the channel position of the PBCH being determined based on the time domain position of the PSS and the frequency domain position of the SSS; based on the phase difference between the received first reference signal and a local first reference signal, estimating the basic frequency shift value of the terminal relative to the wave position center.

6. The method of claim 4, wherein, The estimation of the dynamic frequency shift value generated by the terminal in the time interval of the SSB period based on the pre-compensated downlink signal sent by the first cell comprises: The downlink signal is based on a pre-compensated downlink signal sent by the first cell to obtain a second reference signal; and based on a phase difference between the received second reference signal and a local second reference signal, the terminal estimates a dynamic frequency shift value relative to the wave position center.

7. A Doppler shift compensation device, the device is applied to a satellite-based station, comprising: a first frequency shift compensation unit configured to obtain ephemeris information of a satellite; based on the ephemeris information and the estimated first frequency shift value of the wave position center, compensating the synchronization signal block (SSB) in the wave position and sending the pre-compensated SSB to the terminal; a second frequency shift compensation unit configured to compensate the uplink signal and the downlink signal in the wave position based on the second frequency shift value updated by interpolation, and send the pre-compensated downlink signal to the terminal.

8. The apparatus of claim 7, wherein, The first frequency shift compensation unit estimates the first frequency shift value of the wave position center in the following way: Based on the ephemeris information, the ground projection point of the satellite, the satellite motion direction and the satellite orbit height are obtained; Based on the distance between the wave position center and the ground projection point and the satellite motion direction, the first included angle between the ground projection point and the satellite motion direction and the wave position center is obtained, and based on the distance between the wave position center and the ground projection point, the current position of the satellite and the second included angle between the geocenter and the wave position center are obtained; Based on the ephemeris information, the first included angle and the second included angle, the Doppler shift of the wave position center is estimated to obtain the first frequency shift value of the wave position center.

9. The apparatus of claim 7, wherein, The second frequency shift compensation unit obtains the second frequency shift value updated by interpolation in the following way: Based on the Doppler shift deviation change rate and the time interval of the SSB period, the first frequency shift value of the wave position center is updated by interpolation to obtain the second frequency shift value of the wave position center in the time interval.

10. A Doppler shift compensation device, the device is applied to a terminal, comprising: a basic frequency shift compensation unit configured to receive a pre-compensated synchronization signal block (SSB) sent by a first cell, the first cell being a cell whose signal quality meets the evaluation standard; based on the pre-compensated SSB, estimating a basic frequency shift value of the terminal relative to the wave position center, the basic frequency shift value being used to compensate the Doppler shift of the first downlink signal; a dynamic frequency shift compensation unit configured to compensate the Doppler shift of the second downlink signal based on the first downlink signal compensated by the basic frequency shift compensation unit, and estimate a dynamic frequency shift value of the terminal in a time interval of the SSB period based on a pre-compensated downlink signal sent by the first cell, the dynamic frequency shift value being used to compensate the Doppler shift of the second downlink signal.

11. The apparatus of claim 10, wherein, The basic frequency shift compensation unit is configured to: detect the primary synchronization signal (PSS) and the secondary synchronization signal (SSS) in the pre-compensated SSB; receive a first reference signal in the physical broadcast channel (PBCH), the channel position of the PBCH being determined based on the time domain position of the PSS and the frequency domain position of the SSS; based on the phase difference between the received first reference signal and a local first reference signal, estimate the basic frequency shift value of the terminal relative to the wave position center.

12. The apparatus of claim 10, wherein, The dynamic frequency shift compensation unit is configured to: The downlink signal obtains a second reference signal based on a pre-compensated downlink signal sent by the first cell; and estimates a dynamic frequency shift value of the terminal relative to a wave position center based on a phase difference between the received second reference signal and a local second reference signal.

13. A computer device comprising a processor and a memory, wherein, The memory stores program code which, when executed by the processor, causes the processor to perform the steps of the method of any one of claims 1-6.

14. A computer-readable storage medium comprising program code for causing a computer device to perform the steps of the method of any one of claims 1-6 when the program product is run on the computer device.

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