Time-frequency offset compensation method, device, equipment, and storage medium for satellite-to-ground link

Abstract

The present application discloses a method, device, equipment and storage medium for compensating time and frequency offset of a satellite-to-ground link, including: determining an actual detection frequency and an actual transmission frequency of a synchronization signal block, determining the difference between the actual detection frequency and the actual transmission frequency as a downlink frequency offset, and determining an uplink frequency offset according to the downlink frequency offset; obtaining satellite ephemeris through a system information block corresponding to an indication of the synchronization signal block, and determining satellite position information and satellite speed information of the satellite according to the satellite ephemeris; obtaining satellite beam angle information through a system information block, and determining a value range of a satellite angle according to the beam angle information, the downlink frequency offset and the satellite speed information; determining a value range of a satellite-to-ground distance according to the value range of the satellite angle and the satellite position information, determining a time offset range according to the value range of the satellite-to-ground distance, and determining an uplink time offset within the time offset range according to a random access method; and compensating uplink and downlink signals according to the uplink frequency offset, the uplink time offset and the downlink frequency offset.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a method, device, equipment, and storage medium for compensating time and frequency offset of a satellite-to-ground link. Background Art

[0002] Non-Terrestrial Network (NTN) refers to a wireless network carried by artificial satellites or unmanned aircraft systems (UAS) platforms. Starting from the R17 version, the 3GPP standard organization has included non-terrestrial network technology in the specifications as part of the 5G standard, so as to achieve coverage of thousands of kilometers through satellite-sky chain relays, and complement terrestrial communications to jointly build a three-dimensional integrated network of air, space and land. Compared with traditional 5G terrestrial communications, non-terrestrial network technology can provide good supplementary services, such as coverage blind spots, large-scale broadcasting, and support for high-speed mobile users (such as passengers in passenger aircraft and other transportation vehicles).

[0003] In the existing technology, the implementation process of non-ground network technology is: through payload transparent transmission or payload regeneration satellites or high-altitude USA platforms, communication beams are generated and elliptical illumination areas are formed in the service area to provide service coverage for users. Among them, low-orbit (LEO) satellites carrying satellite base stations are a mainstream architecture solution. Compared with other carriers, low-orbit satellites have the characteristics of short satellite-to-ground distance and high signal strength. However, when low-orbit satellites move rapidly in orbit, the propagation delay of the satellite-to-ground link between the satellite base station and the terminal and the Doppler frequency deviation caused by the mutual speed will continue to change, thereby affecting the communication quality between the satellite base station and the terminal. Summary of the invention

[0004] The present application provides a method, device, equipment, and storage medium for compensating time and frequency offset of a satellite-to-ground link, so as to determine the frequency offset according to the deviation between the actual detection frequency of the synchronization signal block detected and the actual transmission frequency of the synchronization signal block sent, determine the value range of the satellite angle according to the satellite motion state, the downlink frequency offset, and the satellite beam angle, and then determine the time offset range based on the value range of the satellite angle, determine the time offset based on the time offset range during the random access process, and realize the estimation of the time offset and frequency offset of the satellite-to-ground link under the premise of unknown terminal position coordinates, get rid of the dependence on the global positioning system, and be suitable for cost-controlled terminal equipment. Compensating the uplink and downlink signals based on the frequency offset and time offset solves the problem of the time offset and frequency offset of the satellite-to-ground link affecting the communication quality in the prior art, and improves the communication quality between the satellite base station and the ground terminal.

[0005] In a first aspect, the present application provides a method for compensating time-frequency offset of a satellite-to-ground link, which is applied to a ground terminal and includes:

[0006] Perform traversal detection on the synchronization signal block based on each first candidate frequency point of the global synchronization channel number, and determine the actual detection frequency point at which the synchronization signal block is detected;

[0007] Determine an actual transmission frequency for sending the synchronization signal block according to the synchronization signal block, determine a difference between the actual detection frequency and the actual transmission frequency as a downlink frequency offset, and determine an uplink frequency offset according to the downlink frequency offset;

[0008] Acquire satellite ephemeris through the system information block indicated by the synchronization signal block, and determine satellite position information and satellite speed information according to the satellite ephemeris;

[0009] Acquire the beam angle information of the satellite through the system information block, and determine the value range of the satellite angle according to the beam angle information, the downlink frequency deviation and the satellite speed information;

[0010] Determine a value range of a satellite-to-ground distance according to a value range of the satellite angle and the satellite position information, determine a time deviation range according to the value range of the satellite-to-ground distance, and determine an uplink time deviation in the time deviation range according to a random access method;

[0011] An uplink signal is compensated according to the uplink frequency deviation and the uplink time deviation, and a downlink signal is compensated according to the downlink frequency deviation.

[0012] In a second aspect, the present application provides a time-frequency offset compensation device for a satellite-to-ground link, which is applied to a ground terminal, and includes:

[0013] A detection frequency determination module is configured to perform traversal detection on the synchronization signal block based on each first candidate frequency of the global synchronization channel number, and determine an actual detection frequency at which the synchronization signal block is detected;

[0014] a frequency deviation determination module, configured to determine an actual transmission frequency for sending the synchronization signal block according to the synchronization signal block, determine a difference between the actual detection frequency and the actual transmission frequency as a downlink frequency deviation, and determine an uplink frequency deviation according to the downlink frequency deviation;

[0015] a satellite information determination module, configured to obtain satellite ephemeris through a system information block indicated by the synchronization signal block, and determine satellite position information and satellite speed information of the satellite according to the satellite ephemeris;

[0016] a satellite angle determination module, configured to obtain beam angle information of the satellite through the system information block, and determine a value range of the satellite angle according to the beam angle information, the downlink frequency deviation and the satellite speed information;

[0017] A time deviation determination module is configured to determine a value range of a satellite-to-ground distance according to a value range of the satellite angle and the satellite position information, determine a time deviation range according to the value range of the satellite-to-ground distance, and determine an uplink time deviation in the time deviation range according to a random access method;

[0018] The time-frequency offset compensation module is configured to compensate the uplink signal according to the uplink frequency offset and the uplink time offset, and to compensate the downlink signal according to the downlink frequency offset.

[0019] In a third aspect, the present application provides a time-frequency offset compensation device for a satellite-to-ground link, including:

[0020] One or more processors; a memory storing one or more programs, when the one or more programs are executed by the one or more processors, the one or more processors implement the time-frequency offset compensation method of the satellite-to-ground link as described in the first aspect.

[0021] In a fourth aspect, the present application provides a storage medium comprising computer executable instructions, which, when executed by a computer processor, are used to perform the time-frequency offset compensation method for the satellite-to-ground link as described in the first aspect.

[0022] In the present application, the synchronization signal block is traversed and detected through each first candidate frequency point of the global synchronization channel number to determine the actual detection frequency point of the detected synchronization signal block; the actual transmission frequency point for sending the synchronization signal block is determined according to the synchronization signal block, the difference between the actual detection frequency point and the actual transmission frequency point is determined as the downlink frequency deviation, and the uplink frequency deviation is determined according to the downlink frequency deviation; the satellite ephemeris is obtained through the system information block corresponding to the indication of the synchronization signal block, and the satellite position information and the satellite speed information are determined according to the satellite ephemeris; the beam angle information of the satellite is obtained through the system information block, and the value range of the satellite angle is determined according to the beam angle information, the downlink frequency deviation and the satellite speed information; the value range of the satellite-to-earth distance is determined according to the value range of the satellite angle and the satellite position information, the time deviation range is determined according to the value range of the satellite-to-earth distance, and the uplink time deviation is determined in the time deviation range according to the random access method; the uplink signal is compensated according to the uplink frequency deviation and the uplink time deviation, and the downlink signal is compensated according to the downlink frequency deviation. Through the above technical means, the frequency deviation is determined according to the deviation between the actual detection frequency of the synchronization signal block and the actual transmission frequency of the synchronization signal block, the satellite angle value range is determined according to the satellite motion state, the downlink frequency deviation and the satellite beam angle, the time deviation range is determined based on the satellite angle value range, and the uplink time deviation is determined in the time deviation range according to the random access method. Under the premise that the ground terminal is not equipped with a receiving module of the global navigation satellite system, the time and frequency deviation of the satellite-to-ground link can also be accurately estimated, effectively reducing the manufacturing cost and use cost of the ground terminal. The uplink and downlink signals are compensated based on the frequency deviation and time deviation range, which solves the problem that the time deviation and frequency deviation of the satellite-to-ground link affect the communication quality in the prior art, and improves the communication quality between the satellite base station and the terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of a method for compensating time-frequency offset of a satellite-to-ground link provided in an embodiment of the present application;

[0024] Figure 2 This is a flow chart of determining the actual transmission frequency based on the system information block provided by an embodiment of the present application;

[0025] Figure 3 It is a flowchart of determining the actual transmission frequency based on the low-order part of the cell identifier provided in an embodiment of the present application;

[0026] Figure 4 It is one of the schematic diagrams of the triangle formed by the center of the earth, the satellite and the ground terminal provided in the embodiment of the present application;

[0027] Figure 5 It is a flow chart of determining the value range of the satellite angle provided by an embodiment of the present application;

[0028] Figure 6 It is one of the schematic diagrams of the satellite motion state provided in the embodiment of the present application;

[0029] Figure 7 This is the second schematic diagram of the satellite motion state provided in the embodiment of the present application;

[0030] Figure 8 is a flow chart for determining a value range of a satellite-to-earth distance provided in an embodiment of the present application;

[0031] Fig. 9 This is the second schematic diagram of the triangle formed by the center of the earth, the satellite and the ground terminal provided in the embodiment of the present application;

[0032] Fig.10 It is a flow chart of performing time deviation compensation for an uplink signal according to a time deviation range provided in an embodiment of the present application;

[0033] Fig.11 It is a structural schematic diagram of a time-frequency offset compensation device for a satellite-to-ground link provided in an embodiment of the present application;

[0034] Fig.12 It is a structural schematic diagram of a time-frequency offset compensation device for a satellite-to-ground link provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present application clearer, the specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. It is understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for the convenience of description, only part of the present application is shown in the accompanying drawings, but not all of the content. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow chart describes each operation (or step) as a sequential process, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but it can also have additional steps not included in the accompanying drawings. The process can correspond to a method, a function, a procedure, a subroutine, a subprogram, etc.

[0036] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0037] In the more common existing implementation methods, satellite base stations are carried by low-orbit satellites, and non-ground network communication is carried out between satellite base stations and ground terminals. Although low-orbit satellites have the characteristics of short satellite-to-ground distance and strong signal quality compared with other carriers. However, when low-orbit satellites move rapidly in orbit, the propagation delay and Doppler frequency deviation of the satellite-to-ground link between the satellite base station and the ground terminal will continue to change, thereby affecting the communication quality between the satellite base station and the terminal. In addition, according to the NTN specification, the ground terminal can estimate the time deviation and frequency deviation of the satellite-to-ground link by receiving the ephemeris information broadcast by the satellite base station and combining its own navigation and positioning information, and the ground terminal compensates for the time deviation and frequency deviation. The navigation and positioning information of the ground terminal is generally obtained through the integrated global navigation satellite system (GNSS) receiving module. However, in some scenarios, due to cost considerations for the ground terminal, not every ground terminal will be equipped with a global navigation satellite system receiving module. In the absence of navigation and positioning information input, the ground terminal cannot complete the estimation of the time and frequency deviation based on the ephemeris information alone, and thus cannot compensate for the time and frequency deviation of the uplink and downlink signals, resulting in the inability to communicate normally between the satellite base station and the ground terminal.

[0038] To solve the above problems, this embodiment provides a method for compensating time and frequency offset of a satellite-to-ground link, so as to determine the frequency offset according to the deviation between the actual detection frequency of a synchronization signal block detected and the actual transmission frequency of a synchronization signal block sent, determine the value range of the satellite angle according to the satellite motion state, the downlink frequency offset and the beam angle of the satellite, and then determine the time offset range based on the value range of the satellite angle, determine the time offset based on the time offset range during the random access process, and accurately estimate the time and frequency offset of the satellite-to-ground link without obtaining the navigation positioning information of the ground terminal; compensate for the uplink and downlink signals based on the frequency offset and the time offset, thereby improving the communication quality between the satellite base station and the terminal and ensuring the normal communication between the satellite base station and the ground terminal.

[0039] The satellite-to-ground link time-frequency offset compensation method provided in this embodiment may be executed by a satellite-to-ground link time-frequency offset compensation device, which may be implemented by software and / or hardware, and which may be composed of two or more physical entities or one physical entity. For example, the satellite-to-ground link time-frequency offset compensation device may be a ground terminal or a processor of the ground terminal.

[0040] The satellite-to-ground link time-frequency offset compensation device is installed with at least one type of operating system, wherein the operating system includes but is not limited to Android system, Linux system and Windows system. The satellite-to-ground link time-frequency offset compensation device can install at least one application based on the operating system, and the application can be an application that comes with the operating system, or an application downloaded from a third-party device or server. In this embodiment, the satellite-to-ground link time-frequency offset compensation device has at least an application that can execute the satellite-to-ground link time-frequency offset compensation method.

[0041] For ease of understanding, this embodiment is described by taking a ground terminal as the main body of the satellite-to-ground link time-frequency offset compensation method as an example.

[0042] Figure 1 1 is a flow chart of a method for compensating time-frequency offset of a satellite-to-ground link provided in an embodiment of the present application. Figure 1 As shown, the steps of the time-frequency offset compensation method of the satellite-to-ground link include:

[0043] S110. Perform traversal detection on the synchronization signal block based on each first candidate frequency point of the global synchronization channel number to determine the actual detection frequency point at which the synchronization signal block is detected.

[0044] Exemplarily, a synchronization signal block is sent from a satellite to a ground terminal. During the transmission of the synchronization signal block, the propagation frequency of the synchronization signal block changes, resulting in a deviation between the frequency at which the satellite sends the synchronization signal block and the frequency at which the ground terminal receives the synchronization signal block. This deviation is the downlink frequency deviation when the satellite communicates with the ground terminal. In this regard, this embodiment aims to determine the downlink frequency deviation based on the difference between the sending frequency and the receiving frequency of the synchronization signal block.

[0045] In this embodiment, the first candidate frequency is a candidate frequency for detecting a synchronization signal block. In order to improve the detection efficiency of the synchronization signal block, the synchronization signal block can be traversed and detected through the frequency of the global synchronization channel number, so that the frequency of the detected synchronization signal block is used as the actual detection frequency of the synchronization signal block, that is, the frequency at which the ground terminal receives the synchronization signal block. It can be seen from the 3GPP specification that the global synchronization channel number ranges from 2 to 26639, and different ranges of global synchronization channel numbers correspond to different frequency ranges. Table 1 is a mapping table of the global synchronization channel number range and the frequency range provided in an embodiment of the present application.

[0046] Table 1

[0047]

[0048] As shown in Table 1, the global synchronization channel number is divided into three ranges, namely 2~7498, 7499~22255 and 22256~26639, and the frequency range is also divided into three ranges, namely 0~3000, 3000~24250 and 24250~100000. N * 1200kHz + M * 50 kHz, 3000MHz + N * 1.44MHz and 24250.08 MHz + N *17.28MHz are respectively the calculation formulas for the global synchronization channel number corresponding to the frequency points in the three ranges, and 3N + (M-3) / 2, 7499 +N and 22256 + N are respectively the calculation formulas for the global synchronization channel number in the three ranges. The parameter N and / or parameter M corresponding to each global synchronization channel number can be determined according to the calculation formula of the global synchronization channel number, and the frequency point corresponding to the global synchronization channel number is calculated based on the parameter N and / or parameter M and the frequency point calculation formula. In one embodiment, the frequency point corresponding to each global synchronization channel number can be used as the first candidate frequency point, so as to traverse and detect the synchronization signal block through the frequency point corresponding to each global synchronization channel number. When the synchronization signal block is detected at the frequency point of a certain global synchronization channel number, the frequency point of the global synchronization channel number is used as the actual detection frequency point of the synchronization signal block.

[0049] Since there are many frequencies corresponding to all global synchronization channel numbers, the efficiency of traversing and detecting synchronization signal blocks based on the frequencies corresponding to all global synchronization channel numbers is low. In this regard, the search range of the global synchronization channel number can be determined according to the network frequency band and subcarrier spacing where the ground terminal is located; the frequency corresponding to each global synchronization channel number in the search range is used as the first candidate frequency; the synchronization signal block is detected based on each first candidate frequency, and the first candidate frequency detected in the synchronization signal block is determined as the actual detection frequency. Exemplarily, the search range of the global synchronization channel number is determined according to the network frequency band and subcarrier spacing. When the search range is in the range of 2~7498, the frequency corresponding to each global synchronization channel number in the search range can be determined based on the calculation formula 3N + (M-3) / 2 and N * 1200kHz + M *50 kHz. When the search range is in the range of 3000~24250, the frequency corresponding to each global synchronization channel number in the search range can be determined based on the calculation formula 7499 + N and 3000MHz + N * 1.44MHz. When the search range is within 24250~100000, the frequency point corresponding to each global synchronization channel number in the search range can be determined based on the calculation formulas 22256 + N and 24250.08 MHz + N * 17.28MHz. The frequency point corresponding to each global synchronization channel number in the search range is used as the first candidate frequency point to reduce the number of frequencies used to detect synchronization signal blocks, thereby improving the detection efficiency of synchronization signal blocks.

[0050] In this embodiment, after taking the frequency point corresponding to each global synchronization channel number in the search range as the first candidate frequency point, the corresponding frequency range is determined based on the first candidate frequency point, and the offset frequency point corresponding to the first candidate frequency point is determined in the frequency range of the first candidate frequency point according to the preset step frequency deviation, wherein the first candidate frequency point and the corresponding offset frequency point differ by an integer multiple of the preset step frequency deviation; the synchronization signal block is detected according to the first candidate frequency point and the corresponding offset frequency point, and the frequency point with the largest detection peak is determined as the actual detection frequency point. Among them, the frequency shift range of the first candidate frequency point can be set according to actual needs, for example, the first candidate frequency point of the i-th global synchronization channel number The frequency range can be set to , correspondingly, the first candidate frequency The corresponding offset frequency is , , The present embodiment determines the offset frequency corresponding to the first candidate frequency point in the frequency range of the first candidate frequency point based on the preset step frequency deviation, and detects the synchronization signal block according to the first candidate frequency point and the corresponding offset frequency point, so as to reduce the frequency difference used to detect the synchronization signal block, improve the detection accuracy of the actual detection frequency, and further improve the accuracy of the frequency deviation.

[0051] S120. Determine an actual transmission frequency for sending the synchronization signal block according to the synchronization signal block, determine a difference between an actual detection frequency and an actual transmission frequency as a downlink frequency deviation, and determine an uplink frequency deviation according to the downlink frequency deviation.

[0052] For example, due to the existence of a large frequency offset between satellite-to-ground communications, it is not possible to simply use the local principle to take the frequency corresponding to the global synchronization channel number closest to the actual detection frequency as the actual transmission frequency for sending the synchronization signal block. Therefore, after the synchronization signal block is detected, the actual transmission frequency of the synchronization signal block can be determined based on the indication information of the synchronization signal block.

[0053] In one embodiment, a frequency field for storing the actual transmission frequency can be added to the system information block corresponding to the indication of the synchronization signal block. When the synchronization signal block is detected, the corresponding system information block can be detected based on the synchronization signal block, and the actual transmission frequency can be obtained from the frequency field of the system information block. Exemplarily, Figure 2 1 is a flow chart of determining the actual transmission frequency based on the system information block provided by an embodiment of the present application. Figure 2 As shown, the step of determining the actual transmission frequency based on the system information block specifically includes S1201-S1202:

[0054] S1201. Obtain a master information block in a physical broadcast channel of a synchronization signal block, and obtain an indication message of a system information block in the master information block.

[0055] S1202: Detect a system information block on the initial bandwidth part according to the indication message, and obtain an actual transmission frequency for sending a synchronization signal block in a frequency field of the system information block.

[0056] Exemplarily, the synchronization signal block includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). The physical broadcast channel carries the MIB (master information block), which contains an indication message that instructs the ground terminal how to obtain the system information block. Based on the indication message in the MIB, the system information block (SIB) can be detected on the initial bandwidth part, and the actual transmission frequency can be obtained in the frequency field of the detected system information block.

[0057] In another embodiment, the cell identifier is a basic factor in the generation of physical layer signals, and different terminals using the cell identifier can distinguish the signals of adjacent cells. Considering that the cell range formed by the coverage beam of the non-terrestrial network is much larger than that of the terrestrial network, the corresponding number of cells is much less than that of the terrestrial network. Therefore, when the number of required cells is reduced, the cell identifier can extract some components to represent the information of the global synchronization channel number used to send the synchronization signal block, such as the low-order part of the cell identifier is the same as the low-order part of the global synchronization channel number used to send the synchronization signal block, that is, the low-order part of the cell identifier is the same as the low-order part of the global synchronization channel number corresponding to the actual transmission frequency. In this regard, the actual transmission frequency can be determined based on the low-order part of the cell identifier. Exemplarily, Figure 3 1 is a flow chart of determining the actual transmission frequency based on the low-order part of the cell identifier provided in an embodiment of the present application. Figure 3 As shown, the step of determining the actual transmission frequency based on the low-order part of the cell identifier specifically includes S1203-S1205:

[0058] S1203: Determine a cell identification sequence through a primary synchronization signal and a secondary synchronization signal of a synchronization signal block, and obtain a low-order portion of the cell identification sequence.

[0059] S1204: According to the global synchronization channel number of the actually detected frequency point, determine a candidate frequency point set from the frequency points corresponding to a plurality of consecutive global synchronization channel numbers.

[0060] S1205. Determine a matching frequency point in the candidate frequency point set where the low-order part of the global synchronization channel number is the same as the low-order part of the cell identification sequence, and determine the matching frequency point as the actual transmission frequency point for sending the synchronization signal block.

[0061] Exemplarily, a corresponding cell identification sequence can be generated according to the cell identification carried by the primary synchronization signal and the secondary synchronization signal of the synchronization signal block, and the lower 2 bits in the cell identification sequence can represent the lower 2 bits of the global synchronization channel number of the synchronization signal block. The ground terminal can obtain the lower 2 bits in the cell identification sequence. Select 4 frequency points closest to the actual detection frequency point from the frequency points of multiple global synchronization channel numbers that are consecutive before and after the global synchronization channel number of the actual detection frequency point as the second candidate frequency points, and divide the 4 second candidate frequency points into a candidate frequency point set. Compare the lower 2 bits of the global synchronization channel number corresponding to each second candidate frequency point in the candidate frequency point set with the lower 2 bits of the cell identification sequence. If they are the same, the corresponding second candidate frequency point is determined as the matching frequency point, and then the matching frequency point is determined as the actual transmission frequency point. This embodiment selects a second candidate frequency point from the frequency points corresponding to the global synchronization channel number near the actual detection frequency point, compares the low-order part of the cell identification sequence with the low-order part of the global synchronization channel number corresponding to each second candidate frequency point, and quickly determines the second candidate frequency point that is identical to the low-order part of the cell identification sequence based on the low-order part of the global synchronization channel number as the actual transmission frequency point, thereby effectively improving the efficiency of obtaining the actual transmission frequency point.

[0062] After determining the actual transmission frequency, the actual detection frequency minus the actual transmission frequency is used to obtain the downlink frequency deviation. The uplink frequency deviation is determined based on the downlink frequency deviation, the downlink carrier frequency, and the uplink carrier frequency using the preset uplink frequency deviation calculation formula. The uplink frequency deviation calculation formula is:

[0063]

[0064] in, is the uplink frequency deviation, is the downlink frequency deviation, is the downlink carrier frequency, is the uplink carrier frequency.

[0065] S130. Obtain satellite ephemeris through the system information block indicated by the synchronization signal block, and determine satellite position information and satellite speed information according to the satellite ephemeris.

[0066] Exemplarily, the system information block adds an ephemeris field for storing satellite ephemeris. When a synchronization signal block is detected, the master information block can be obtained in the physical broadcast channel of the synchronization signal block, the indication message of the system information block can be obtained in the master information block, the system information block is detected on the initial bandwidth part according to the indication message, and the satellite ephemeris is obtained in the ephemeris field of the system information block. The satellite ephemeris includes the satellite orbit parameters at the reference time, the satellite orbit parameters at the current time can be calculated based on the satellite orbit parameters at the reference time, and the satellite position information and satellite speed information of the satellite at the current time can be determined according to the satellite orbit parameters at the current time.

[0067] According to Kepler's laws of celestial motion, a satellite orbit is an elliptical orbit with the center of the earth as the focus. The elliptical orbit is mainly described by six satellite orbit parameters: semi-major axis, eccentricity, orbital inclination, amplitude of perigee, longitude of ascending node and anomaly angle. Among them, the satellite orbit parameters are based on the geocentric inertial (ECI) coordinate system, the semi-major axis is half the length of the longest line segment that passes through the focus and intersects the ellipse; the eccentricity is the ratio of the semi-focal length to the semi-major axis; the orbital inclination angle represents the inclination of the orbital plane relative to the reference plane; the periapsis argument represents the positional relationship between the periapsis and the reference plane; the ascending node longitude represents the positional relationship of the orbital plane equivalent to the X-axis of the geocentric inertial coordinate system; the anomaly angle has three expressions, namely the true anomaly angle, the eccentric anomaly angle and the mean anomaly angle. The true anomaly angle represents the relative position of the satellite on the orbital focal line; the eccentric anomaly angle is the angle between the position of the satellite on the orbit projected on the circumscribed circle perpendicular to the semi-major axis of the ellipse, and measured from the center of the ellipse and the direction of the periapsis; the mean anomaly angle is the running angle of the corresponding virtual point of the satellite on the auxiliary circle relative to the center point.

[0068] When determining the satellite orbit parameters at the current time based on the satellite orbit parameters at the reference time, the semi-major axis, eccentricity, orbit inclination, argument of pericenter and longitude of ascending node at the reference time can be determined as the semi-major axis, eccentricity, orbit inclination, argument of pericenter and longitude of ascending node at the current time; the mean angular velocity is determined according to the semi-major axis and the gravitational constant, and the mean anomaly at the current time is determined according to the mean angular velocity, the difference between the reference time and the current time, and the mean anomaly at the reference time; the eccentric anomaly at the transmission time is determined according to the mean anomaly and the eccentricity at the current time.

[0069] For example, for the same satellite, the semi-major axis, eccentricity, orbital inclination, argument of perigee and longitude of ascending node in the corresponding satellite orbit parameters at different times are the same. Therefore, the semi-major axis, eccentricity, orbital inclination, argument of perigee and longitude of ascending node at the reference time can be directly determined as the semi-major axis, eccentricity, orbital inclination, argument of perigee and longitude of ascending node at the current time.

[0070] The periapsis is the only variable in the satellite orbit parameters, and the eccentric anomaly will be used in determining the satellite's position and velocity later, so the eccentric anomaly at the current moment can be determined. The eccentric anomaly and the mean anomaly satisfy the Kepler equation ,in, is the anomaly angle at the current moment, is the mean anomaly at the current moment, and e is the eccentricity at the current moment. Therefore, the mean anomaly at the current moment can be determined first, and then the eccentric anomaly at the current moment can be determined.

[0071] The formula for calculating the angular velocity of horizontal motion is: , is the angular velocity of horizontal motion, is the gravitational constant, , is the gravitational constant, is the mass of the Earth, is the semi-major axis at the current moment. Substituting the gravitational constant and the semi-major axis at the current moment into the calculation formula of the angular velocity of mean motion, the angular velocity of mean motion can be calculated. The angular velocity of mean motion is multiplied by the time difference between the current moment and the reference moment to obtain the product, and the product is added to the mean anomaly angle at the reference moment to obtain the sum value, and the sum value is added to the arc of the circle, that is, The mean anomaly angle at the current moment is obtained by performing a remainder operation. It should be noted that the above calculation process can be used to infer the mean anomaly angle calculation formula: , is the mean anomaly at the reference time, T is the current time, is the reference time, is the symbol of the remainder operation. Substituting the reference time, the current time, the mean anomaly angle and the angular velocity of the horizontal motion at the reference time into the mean anomaly angle calculation formula, the mean anomaly angle at the current time can be calculated. Based on the mean anomaly angle and eccentricity at the current time, the Kepler equation By solving, we can get the current anomaly angle. When the satellite orbit is circular, the anomaly angle Equal to the mean anomaly When the eccentricity When the satellite orbit is elliptical, the Kepler equation can be solved by iteration. ,because , the iteration It is convergent. . The initial , set reasonable control standards , when the control standard is met, that is, the convergence gap is less than a specific threshold, the iteration can be ended, and the final As the solution to Kepler's equation, that is, as the eccentric anomaly angle at the current moment.

[0072] After determining the satellite orbit parameters at the current moment, the satellite velocity information and satellite position information of the satellite at the current moment can be determined based on the right ascension angle and the satellite orbit parameters at the current moment. Exemplarily, the satellite orbit parameters are referenced to the geocentric inertial (ECI) coordinate system, and the satellite velocity and position used to determine the time deviation and frequency deviation of the satellite-to-ground link are referenced to the geocentric earth-fixed (ECEF) coordinate system. Both coordinate systems use the geocentric origin and the North Pole as the Z-axis direction, but the geocentric inertial coordinate system uses the vernal equinox (i.e., the intersection of the ecliptic plane and the equator) as the X-axis direction, and the geocentric earth-fixed coordinate system uses 0 longitude and the intersection of the equator as the X-axis direction. Therefore, the deflection angle between the X-axis of the geocentric inertial coordinate system and the X-axis of the geocentric earth-fixed coordinate system is equal to the right ascension angle. After the satellite orbit parameters are converted to the geocentric earth-fixed coordinate system through the right ascension angle, the satellite velocity and satellite position in the geocentric earth-fixed coordinate system can be determined.

[0073] In this embodiment, the right ascension angle is the angle from the vernal equinox along the celestial equator eastward to the intersection of the celestial time circle and the celestial equator. The time interval between noon on the vernal equinox of the year corresponding to the current moment and the current moment can be determined, and the time ratio of the time interval to the earth's rotation period is determined. The product of the decimal part of the time ratio and the arc of the circle is determined as the right ascension angle. Exemplarily, noon on the vernal equinox is 12:00 noon on the vernal equinox. The transmission time is subtracted from 12:00 noon on the vernal equinox of the same year as the current moment, and the calculated difference is used as the time interval. The time ratio is obtained by dividing the time interval by the earth's rotation period. Since the time interval and the earth's rotation period are divided by the same time unit, the time ratio obtained by dividing the two is in days. The rotation angle corresponding to one day is The fractional part of the time ratio is a period of time that does not exceed one day. Multiplying this period of time by the arc of the circle gives , you can get the right ascension angle corresponding to the current moment.

[0074] It can be understood that the above calculation process can be deduced that the calculation formula for the right ascension angle is:

[0075]

[0076] in, is the right ascension angle, is the Earth's rotation period, The time interval between the current time and 12:00 noon on the spring equinox in the same year. Substituting the time interval and the Earth's rotation period into the above calculation formula can calculate the right ascension angle.

[0077] After determining the right ascension angle at the current moment, the unit vectors of the pericenter and semi-diameter directions in the geocentric Earth-fixed coordinate system can be determined based on the pericenter argument, ascending node longitude, orbital inclination and right ascension angle at the current moment; the velocity vector and position vector of the satellite in the geocentric Earth-fixed coordinate system can be determined based on the unit vectors of the pericenter and semi-diameter directions in the geocentric Earth-fixed coordinate system and the semi-major axis, eccentricity and eccentric anomaly angle at the transmission time.

[0078] For example, if in a rectangular coordinate system with the orbital plane as the XY plane, the X axis points to the pericenter direction, then the initial unit vector of the pericenter is , and the unit vector of the pericenter in the Earth-centered Earth-fixed coordinate system is The initial unit vector Multiply the rotation matrix on the left to get the unit vector of the pericenter in the Earth-centered Earth-fixed coordinate system. With the initial unit vector The expressions between are as follows:

[0079]

[0080] in, is the current moment's argument of pericenter, is the orbital inclination at the current moment, , is the longitude of the ascending node at the current moment, is the right ascension angle at the current moment, is the first rotation matrix, is the second rotation matrix, is the third rotation matrix. The growth direction of the right ascension angle is from east to west, which is opposite to the longitude. The longitude of the ascending node of the geocentric inertial coordinate system can be obtained by correcting the right ascension angle to obtain the longitude of the ascending node of the geocentric earth-fixed coordinate system, ensuring the accuracy of the calculation.

[0081] If the X-axis points to the semi-diameter direction in the rectangular coordinate system with the orbital plane as the XY plane, then the initial unit vector in the semi-diameter direction is , so the unit vector of the semi-diameter direction in the Earth-centered Earth-fixed coordinate system is The initial unit vector Multiply the rotation matrix on the left to get the unit vector of the semi-diameter direction in the Earth-centered Earth-fixed coordinate system With the initial unit vector The expressions between are as follows:

[0082]

[0083] in, is the third rotation matrix.

[0084] It can be seen from the above expressions that the first rotation matrix can be determined according to the opposite number of the pericenter argument, the second rotation matrix can be determined according to the opposite number of the orbital inclination, the third rotation matrix can be determined according to the opposite number of the difference between the longitude of the ascending node and the right ascension angle, and the fourth rotation matrix can be determined according to the difference between the opposite number of the pericenter argument and the ninety-degree angle; the initial unit vector of the pericenter is rotated and transformed according to the first rotation matrix, the second rotation matrix and the third rotation matrix to obtain the unit vector of the pericenter in the geocentric earth-fixed coordinate system; the initial unit vector of the semi-diameter direction is rotated and transformed according to the fourth rotation matrix, the second rotation matrix and the third rotation matrix to obtain the unit vector of the semi-diameter direction in the geocentric earth-fixed coordinate system. Among them, the expressions of the first rotation matrix, the second rotation matrix, the third rotation matrix and the fourth rotation matrix are as follows:

[0085]

[0086]

[0087]

[0088]

[0089] From the expressions of the first rotation matrix, the second rotation matrix, the third rotation matrix and the fourth rotation matrix, the first rotation matrix can be obtained by substituting the opposite number of the pericentric angle into the matrix calculation formula for rotation around the Z axis, the second rotation matrix can be obtained by substituting the opposite number of the orbital inclination into the matrix calculation formula for rotation around the X axis, the third rotation matrix can be obtained by substituting the opposite number of the difference between the longitude of the ascending node and the right ascension angle into the matrix calculation formula for rotation around the Z axis, and the fourth rotation matrix can be obtained by substituting the difference between the opposite number of the pericentric angle and the ninety-degree angle into the matrix calculation formula for rotation around the Z axis. The unit vector of the pericentric point in the geocentric earth-fixed coordinate system can be obtained by left-multiplying the initial unit vector of the pericentric point by the third rotation matrix, the second rotation matrix and the first rotation matrix in sequence. The unit vector of the semi-diameter direction in the geocentric earth-fixed coordinate system can be obtained by left-multiplying the initial unit vector of the semi-diameter direction by the fourth rotation matrix, the second rotation matrix and the first rotation matrix in sequence.

[0090] It should be noted that the expressions of the first rotation matrix, the second rotation matrix, the third rotation matrix and the initial unit vector of the pericentric point are substituted into , we can deduce that the unit vector of the pericenter in the Earth-centered Earth-fixed coordinate system is The calculation formula is:

[0091]

[0092] Substitute the expressions for the first rotation matrix, the second rotation matrix, the fourth rotation matrix, and the initial unit vector in the semi-path direction into , we can deduce that the unit vector of the semi-diameter direction in the Earth-centered Earth-fixed coordinate system is The calculation formula is:

[0093]

[0094] Therefore, the argument of perigee, orbital inclination, longitude of ascending node and right ascension angle at the time of transmission can be substituted into The calculation formula and In the calculation formula of and .

[0095] S1204. Determine the velocity vector and position vector of the satellite in the Earth-centered Earth-fixed coordinate system based on the unit vectors of the pericenter and semi-diameter directions in the Earth-centered Earth-fixed coordinate system and the semi-major axis, eccentricity and eccentric anomaly angle at the time of transmission.

[0096] Exemplarily, based on a preset satellite position calculation formula, the position vector of the satellite in the earth-centered earth-fixed coordinate system is determined by the unit vectors of the pericenter and semi-diameter directions in the earth-centered earth-fixed coordinate system and the semi-major axis, eccentricity and eccentric anomaly angle at the time of transmission. The satellite position calculation formula is:

[0097]

[0098] in, is the position vector of the satellite. , eccentricity , near point angle 、Unit vector of the pericenter in the Earth-centered Earth-fixed coordinate system and the unit vector of the semi-diameter direction in the Earth-centered Earth-fixed coordinate system Substituting into the satellite position calculation formula, the satellite position vector can be obtained. .

[0099] Furthermore, based on the preset satellite velocity calculation formula, the satellite velocity vector in the Earth-centered Earth-fixed coordinate system is determined by the unit vectors of the pericenter and semi-diameter directions in the Earth-centered Earth-fixed coordinate system, the semi-major axis, eccentricity and eccentric pericenter angle at the time of transmission, and the position vector of the satellite. The satellite velocity calculation formula is:

[0100]

[0101] in, is the satellite's velocity vector, is the modulus of the satellite's position vector. , eccentricity , near point angle 、Unit vector of the pericenter in the Earth-centered Earth-fixed coordinate system , the unit vector of the semi-diameter direction in the Earth-centered Earth-fixed coordinate system , gravitational constant and the modulus of the satellite's position vector Substituting into the satellite velocity calculation formula, the satellite velocity vector can be obtained. .

[0102] S140. Obtain the beam angle information of the satellite through the system information block, and determine the value range of the satellite angle according to the beam angle information, downlink frequency deviation and satellite speed information.

[0103] For example, Figure 4 1 is one of the schematic diagrams of the triangle formed by the center of the earth, the satellite and the ground terminal provided in the embodiment of the present application. Figure 4 As shown, point O is the center of the earth, point S is the satellite, point P is the ground terminal, and r is the radius of the earth. In △OSP, |OS| is equal to the distance between the satellite position and the center of the earth, |OP| is equal to the radius of the earth r, and |SP| is equal to the length of the satellite-to-ground link, that is, the satellite-to-ground distance. is the satellite angle, is the geocentric angle, is the terminal angle. According to the triangle sine theorem, |OS|, |OP|, |SP| and , and The following relations are satisfied:

[0104]

[0105] in, is the radius of the triangle circumscribed circle of △OSP. Since the satellite position has been calculated in step S130, and the geocentric position and the earth radius r are known, |OS| can be determined based on the satellite position and the geocentric position, and |OP| can be determined based on the earth radius r. The value range of can be determined by the satellite beam angle information, downlink frequency deviation and satellite speed. After finding the value range of |SP|, the value range of |SP| can be deduced through the above relationship, and then the satellite-to-earth distance can be determined.

[0106] In this embodiment, the beam angle information includes a beam center angle and a beam width. The system information block is configured with a beam angle information field for storing the beam center angle and beam width of the satellite. When a synchronization signal block is detected, a master information block can be obtained in the broadcast channel of the synchronization signal block, an indication message of the system information block can be obtained in the master information block, the system information block is detected on the initial bandwidth part according to the indication message, and the beam center angle and beam width are obtained in the beam angle information field of the system information block. Figure 4 , beam center angle The angle between the satellite beam main lobe 11 and the earth-center satellite line OS, the beam center angle Determines the specific location where the center of the beam points. Beam width It is the angle between the center of the beam and the two sides when the radiated power of the satellite beam drops by a certain value (such as 3dB) in a specific direction. The beam width determines the ground area that the satellite beam can cover. Generally speaking, when the angle between the satellite-to-ground link SP and the satellite beam main lobe 11 is less than or equal to half the beam width, the ground terminal can receive a stronger communication signal sent by the satellite. As the angle between the satellite-to-ground link SP and the satellite beam main lobe 11 gradually increases, the ground terminal receives a weaker communication signal or no communication signal. Therefore, the range of the satellite angle can be determined based on the beam center angle and the beam width.

[0107] For example, Figure 5 : is a flow chart of determining the value range of the satellite angle provided by the embodiment of the present application. Figure 5 As shown, the step of determining the value range of the satellite angle specifically includes S1401-S1403:

[0108] S1401. Determine the sum of the beam center angle and half the beam width as the maximum value of the satellite angle, and determine the angle difference between the beam center angle and half the beam width.

[0109] refer to Figure 4 , beam center angle and half the beamwidth Together they form the ground area covered by the satellite beam. When the angle between the satellite-to-ground link SP and the satellite beam main lobe 11 is less than or equal to When , it indicates that the ground terminal is in the ground area covered by the satellite beam. is the angle between the earth-center satellite link OS and the satellite-to-earth link SP, from which the satellite angle The maximum value of is equal to the sum of the beam center angle and half the beam width, that is, , is the beam center angle, is the beam width. Satellite angle The minimum value of can be the angle difference between the beam center angle and half the beam width, that is, ,but It may be less than zero, but the satellite angle will not be less than zero, so When it is less than zero, it can be determined that the minimum value of the satellite angle can be zero.

[0110] S1402: Determine a projection angle according to downlink frequency deviation and satellite speed information, and determine a complementary angle of the projection angle, where the projection angle is the angle between the satellite speed direction and the satellite-to-ground link.

[0111] For example, Figure 6 and with Figure 7 Schematic diagram of the satellite motion state provided in the embodiment of the present application. Figure 6 and Figure 7 As shown in the figure, when the satellite speed v, the satellite-to-ground link SP and the earth-center-satellite line OS are coplanar, the satellite angle Angle with projection Mutually complementary, the satellite angle To this end, this embodiment assumes that the current satellite velocity v, the satellite-to-ground link SP, and the geocentric satellite line OS are coplanar. Then, the projection angle The complementary angle is about 90 degrees with the projection angle The difference is determined as the minimum value that the satellite angle can take at the current moment.

[0112] In this embodiment, since the downlink frequency deviation is caused by the Doppler frequency deviation generated by the projection component of the satellite motion speed on the satellite-to-ground link, the projection angle at the current moment can be determined based on the downlink frequency deviation and the satellite speed. Exemplarily, based on a preset projection angle calculation formula, the projection angle is determined by the downlink frequency deviation, the downlink carrier frequency, the electromagnetic wave speed and the satellite speed information; wherein the projection angle calculation formula is:

[0113]

[0114] in, is the projection angle, is the downlink frequency deviation, is the downlink carrier frequency, is the electromagnetic wave speed, is the satellite speed information. Substituting the downlink frequency deviation, downlink carrier frequency, electromagnetic wave speed and satellite speed information into the projection angle calculation formula, the projection angle can be calculated. Subtracting the projection angle from 90 degrees will give the complementary angle of the projection angle, which is the minimum value of the satellite angle.

[0115] It can be understood that when the satellite speed v, the satellite-to-ground link SP and the geocentric-satellite line OS are coplanar, the projection angle and the satellite angle are complementary to each other. At this time, the satellite angle can take the minimum value. Therefore, the calculation formula of the complementary angle of the projection angle, that is, the minimum value of the satellite angle, is:

[0116]

[0117] in, is the complementary angle of the projection angle.

[0118] S1403: Determine the minimum value among the complementary angle, the angle difference and zero as the minimum value of the satellite angle.

[0119] For example, the complementary angle , the angle difference between the beam center angle and half the beam width and zero are the minimum values ​​that the satellite angle can take. The minimum value of these three values ​​can be determined as the minimum value of the satellite angle.

[0120] This embodiment determines the maximum value of the satellite angle by the sum of the beam center angle and half the beam width, determines the candidate minimum value of the satellite angle by the difference between the beam center angle and half the beam width, determines the projection angle by the downlink frequency deviation and the satellite speed, and then determines another candidate minimum value of the satellite angle based on the lower complementary angle of the projection angle. The smaller of the multiple candidate minimum values ​​of the satellite angle is obtained as the minimum value of the satellite angle, so as to accurately locate the value range of the satellite angle, ensure the accuracy of the subsequently calculated time deviation range, ensure the accuracy of the time deviation compensation, and help improve the communication quality between the satellite base station and the terminal.

[0121] S150, determining a value range of the satellite-to-earth distance according to a value range of the satellite angle and satellite position information, determining a time deviation range according to the value range of the satellite-to-earth distance, and determining an uplink time deviation within the time deviation range according to a random access method.

[0122] For example, |OS|, |OP|, |SP| and , and The satisfied relationship shows that, when determining After the value range of The value range of |OP| determines the value range of 2R, and then determines the value range of |OS| The value range of The value range and The value range is determined by The value range of The value range of and the value range of 2R determine the value range of |SP, which is the distance between the star and the earth.

[0123] In this embodiment, Figure 8 1 is a flow chart for determining the value range of the satellite-to-earth distance provided by an embodiment of the present application. Figure 8 As shown, the step of determining the value range of the satellite-to-earth distance specifically includes S1501-S1504:

[0124] S1501. Determine a first ratio between the earth radius and the sine value of the maximum value of the satellite angle, and determine a second ratio between the earth radius and the sine value of the minimum value of the satellite angle.

[0125] For example, the satellite angle is an acute angle, which is composed of |OS|, |OP|, |SP| and , and The satisfied relationship shows that the satellite angle The larger the value, the smaller the 2R, and the satellite angle The smaller it is, the larger 2R is. Therefore, the first ratio between the earth radius and the sine value of the maximum value of the satellite angle can be determined as the minimum value of 2R, and the second ratio between the earth radius and the sine value of the minimum value of the satellite angle can be determined as the maximum value of 2R.

[0126] S1502. Determine a first distance between the satellite and the center of the earth according to the satellite position information and the position of the center of the earth, determine a minimum value of the terminal angle according to the ratio of the first distance to the first ratio, and determine a maximum value of the terminal angle according to the ratio of the first distance to the second ratio.

[0127] The first distance is the length of the Earth-satellite line OS, that is, |OS|. Fig. 9 This is the second schematic diagram of the triangle formed by the center of the earth, the satellite and the ground terminal provided in the embodiment of the present application. Fig. 9 As shown, the terminal angle Always an obtuse angle, As the terminal angle increases, it gradually decreases, so the satellite angle The smaller it is, the larger 2R is, and the terminal angle The larger the satellite angle The larger the value, the smaller the 2R, and the terminal angle Therefore, the ratio of the first distance to the first ratio can be determined as the terminal angle The sine value of the minimum value, according to the terminal angle The sine value of the minimum value determines the terminal angle The ratio of the first distance to the second ratio is determined as the terminal angle The maximum sine value of the terminal angle The sine value of the maximum value determines the terminal angle The maximum value of .

[0128] S1503. Determine the minimum value of the geocentric angle according to the maximum value of the terminal angle and the minimum value of the satellite angle, and determine the maximum value of the geocentric angle according to the minimum value of the terminal angle and the maximum value of the satellite angle.

[0129] refer to Fig. 9, the larger the satellite angle, the smaller the terminal angle, the larger the geocentric angle, the smaller the satellite angle, the larger the terminal angle, the smaller the geocentric angle, and the sum of the satellite angle, the terminal angle and the geocentric angle equals the sum of the triangle's interior angles, 180 degrees. Therefore, the minimum geocentric angle can be obtained by subtracting the maximum value of the terminal angle and the minimum value of the satellite angle from 180 degrees, and the maximum geocentric angle can be obtained by subtracting the minimum value of the terminal angle and the maximum value of the satellite angle from 180 degrees.

[0130] S1504: Determine the maximum value of the satellite-to-earth distance by multiplying the sine value of the maximum value of the geocentric angle by the first ratio, and determine the minimum value of the satellite-to-earth distance by multiplying the sine value of the minimum value of the geocentric angle by the second ratio.

[0131] refer to Fig. 9 The smaller the geocentric angle is, the larger 2R is, and the smaller the satellite-to-ground distance is. The larger the geocentric angle is, the smaller 2R is, and the larger the satellite-to-ground distance is. Therefore, the maximum satellite-to-ground distance can be obtained by multiplying the sine value of the maximum geocentric angle by the first ratio, that is, the minimum value of 2R, and the minimum satellite-to-ground distance can be obtained by multiplying the sine value of the minimum geocentric angle by the first ratio, that is, the maximum value of 2R.

[0132] This embodiment uses the relationship between the satellite angle, the terminal angle, the geocentric angle, the satellite-to-earth distance, the earth radius, and the length of the geocentric-satellite line that satisfies the triangle sine theorem, and accurately calculates the satellite-to-earth distance range through the satellite angle value range, thereby ensuring the accuracy of the subsequently calculated time offset range and the accuracy of the time offset compensation, which is beneficial to improving the communication quality between the satellite base station and the terminal.

[0133] After determining the range of satellite-to-earth distance, the maximum value of the satellite-to-earth distance can be divided by the electromagnetic wave velocity to obtain the maximum value of the time deviation range, and the minimum value of the satellite-to-earth distance can be divided by the electromagnetic wave velocity to obtain the minimum value of the time deviation range.

[0134] After determining the time offset range, the uplink timing advance for sending the random access signal can be gradually determined within the time offset range during the random access process, so as to determine the uplink timing advance that satisfies the uplink time offset according to the response of the random access signal. Fig.10 1 is a flow chart of determining the uplink timing deviation within the timing deviation range provided by the embodiment of the present application. Fig.10 As shown, the step of determining the uplink time deviation within the time deviation range specifically includes S1505-S1508:

[0135] S1505: Determine an initial uplink timing advance according to the minimum value of the time offset range, and send a random access signal based on the uplink timing advance.

[0136] Exemplarily, the ground terminal determines the minimum estimated delay according to the time deviation range, and sets the minimum estimated delay as the initial uplink timing advance. Since the minimum estimated delay includes the outbound delay and the return delay, the minimum estimated delay is equal to twice the minimum value of the time deviation range. Assuming the time deviation range is , then the uplink timing advance can be determined as .

[0137] After determining the initial uplink timing advance, the ground terminal adjusts the transmission time of the uplink signal according to the initial uplink timing advance, and sends a random access signal (PRACH) based on the adjusted transmission time to determine whether the currently set uplink timing advance can accurately transmit the uplink signal to the satellite by whether the random access signal is detected by the network.

[0138] S1506: If no random access response corresponding to the random access signal is received within a preset time, increase the uplink timing advance according to the time length of the cyclic prefix of the random access signal.

[0139] Exemplarily, the cyclic prefix (CP) of the random access signal is to copy the tail part of the preamble sequence of the random access signal to the front of the random access signal, so that the length of the random access signal increases by a CP length. The satellite uses the length of the preamble sequence of the random access signal as the receiving window to receive the random access signal of the cyclic prefix plus the preamble sequence sent by the ground terminal. The uplink timing advance is used to adjust the time when the ground terminal sends the random access signal. If the random access signal sent based on the currently set uplink timing advance falls into the receiving window of the satellite, then the satellite can normally decode the signal received in the receiving window to obtain the preamble sequence of the random access signal. If the random access signal sent based on the currently set uplink timing advance does not fall into the receiving window of the satellite, then the satellite cannot normally decode the signal received in the receiving window to obtain the preamble sequence of the random access signal. Among them, the random access signal falling into the receiving window can be understood as the receiving window receiving all the signals. It can be understood that when the receiving window receives all the signals, the signal in the receiving window is equivalent to the complete preamble sequence in the random access signal, but the preamble sequence has a certain cyclic shift. After correctly decoding the random access signal, the satellite may send a random access response to the ground terminal according to the random access signal. If the random access signal cannot be correctly decoded, the random access response will not be sent to the ground terminal. Therefore, when the ground terminal does not receive the random access response corresponding to the random access signal within the preset time, it indicates that the currently set uplink timing advance cannot upload the uplink signal to the satellite within the satellite's receiving window, and the satellite cannot correctly decode the uplink signal. In this case, the currently set uplink timing advance can be increased by the time length of the CP of the random access signal to determine whether the random access signal sent again falls into the satellite's receiving window based on the increased uplink timing advance.

[0140] It should be noted that the reason why the current uplink timing advance is increased by the time length of the CP of the random access signal in this embodiment is that the advance of the current random access signal is too large compared with the previous random access signal transmission, which causes both the CP and the preamble sequence to move out of the receiving window, resulting in detection failure. If the increase in the uplink timing advance is greater than the time length of the CP, the latter part of the preamble sequence of the random access signal may move out of the receiving window of the satellite, so that the subsequent adjustment of the uplink timing advance cannot ensure that the preamble sequence of the random access signal is delivered within the receiving window of the satellite. If the increase in the uplink timing advance is less than the time length of the CP, multiple adjustments may be required to determine the appropriate uplink timing advance, resulting in low efficiency in time offset estimation. Therefore, this embodiment sets the increase in each uplink timing advance to be equal to the time length of the CP to avoid the preamble sequence of the random access signal from moving out of the receiving window of the satellite while ensuring the efficiency of time offset estimation.

[0141] S1507: When the increased uplink timing advance is less than or equal to twice the maximum value of the timing offset range, resend the random access signal based on the increased uplink timing advance.

[0142] Exemplarily, the maximum estimated delay includes the outbound delay and the return delay, so the maximum estimated delay is equal to twice the maximum value of the time deviation range. Assuming that the time deviation range is , then the uplink timing advance can be determined as When the increased uplink timing advance is less than or equal to the maximum estimated delay, the random access signal may be resent based on the increased uplink timing advance to determine whether the increased uplink timing advance can deliver the preamble sequence of the random access signal within the receiving window of the satellite.

[0143] In this embodiment, when the increased uplink timing advance is greater than twice the maximum value of the time deviation range, the uplink timing advance is adjusted to twice the maximum value of the time deviation range, and the random access signal is resent based on the adjusted uplink timing advance. Exemplarily, if the increased uplink timing advance is greater than twice the maximum value of the time deviation range, it indicates that the increased uplink timing advance will exceed the maximum estimated delay. When the time deviation range is accurately estimated, sending the random access signal based on the maximum estimated delay can make the preamble sequence of the random access signal delivered within the receiving window of the satellite. Therefore, the uplink timing advance can be set to the maximum estimated delay to send the random access signal in advance, thereby improving the communication efficiency between the satellite and the ground terminal.

[0144] If a random access signal is sent based on the maximum estimated delay and still no corresponding random access response is received, it indicates that the currently estimated time offset range is incorrect and the time offset range may be recalculated.

[0145] S1508: When a random access response corresponding to the random access signal is received within a preset time, adjust the uplink timing advance according to the first timing advance instruction in the random access response, and determine the adjusted uplink timing advance as the uplink time offset.

[0146] Exemplarily, if the ground terminal receives a random access response within a preset time, it indicates that the leading sequence of the random access signal can be delivered within the receiving window of the satellite based on the current uplink timing advance. The random access response may also carry a first timing advance instruction, which is used to indicate the ground terminal's fine-tuning amount for the uplink timing advance. The ground terminal can adjust the latest set uplink timing advance based on the fine-tuning amount indicated by the first timing advance instruction, and determine the adjusted uplink timing advance as the uplink time deviation of the uplink signal, so as to compensate for the sending time of the uplink signal to the satellite based on the uplink time deviation in the future, so that the ground terminal and the satellite maintain good uplink synchronization.

[0147] S160: Compensate the uplink signal according to the uplink frequency deviation and the uplink time deviation, and compensate the downlink signal according to the downlink frequency deviation.

[0148] Exemplarily, the ground terminal can adjust the transmission frequency of the uplink signal according to the uplink frequency deviation, so that the propagation frequency of the uplink signal when it reaches the satellite is the same as the frequency of the satellite receiving signal, and send the uplink signal in advance according to the uplink time deviation, so that the uplink signal is delivered within the satellite's receiving window. Among them, the transmission frequency of the uplink signal after adjustment is equal to the difference between the standard transmission frequency and the uplink frequency deviation, and the uplink frequency deviation offsets the frequency deviation effect of the propagation channel and reaches the satellite's base station receiver at a normal frequency. When receiving the downlink signal transmitted by the satellite signal, the ground terminal adjusts its own receiving frequency so that its own receiving frequency is the same as the frequency at which the signal actually arrives. Among them, the frequency at which the signal actually arrives is equal to the sum of the standard transmission frequency and the downlink frequency.

[0149] In one embodiment, after compensating for the time deviation and frequency deviation of the uplink signal, in order to maintain good uplink synchronization between the ground terminal and the satellite and ensure the communication quality between the ground terminal and the satellite, the uplink frequency deviation and the uplink timing advance can be continuously detected, and the transmission frequency and sending time of the uplink signal can be adjusted according to the uplink frequency deviation and the uplink timing advance. Exemplarily, the satellite can detect the uplink DMRS signal or SRS signal, determine the uplink frequency deviation and the uplink timing advance, and indicate the uplink frequency deviation and the uplink timing advance of the uplink signal to the ground terminal through the MAC CE mechanism, so that the ground terminal adjusts the transmission frequency and sending time of the uplink signal according to the indication. Similarly, after compensating for the downlink signal, in order to maintain good downlink synchronization between the ground terminal and the satellite and ensure the communication quality between the ground terminal and the satellite, the downlink frequency deviation can be continuously detected, and the frequency of receiving the downlink signal can be adjusted according to the downlink frequency deviation. Exemplarily, the transmission frequency and the receiving frequency of the synchronization signal block sent by the satellite can be analyzed by the frequency domain detection method, and the downlink frequency deviation can be determined according to the difference between the transmission frequency and the receiving frequency.

[0150] In summary, the time-frequency offset compensation method for the satellite-to-ground link provided in the embodiment of the present application performs traversal detection on the synchronization signal block through each first candidate frequency point of the global synchronization channel number to determine the actual detection frequency point of the detected synchronization signal block; determines the actual transmission frequency point for sending the synchronization signal block according to the synchronization signal block, determines the difference between the actual detection frequency point and the actual transmission frequency point as the downlink frequency offset, and determines the uplink frequency offset according to the downlink frequency offset; obtains the satellite ephemeris through the system information block corresponding to the indication of the synchronization signal block, and determines the satellite position information and the satellite speed information according to the satellite ephemeris; obtains the beam angle information of the satellite through the system information block, and determines the value range of the satellite angle according to the beam angle information, the downlink frequency offset and the satellite speed information; determines the value range of the satellite-to-ground distance according to the value range of the satellite angle and the satellite position information, determines the time offset range according to the value range of the satellite-to-ground distance, and determines the uplink time offset in the time offset range according to the random access method; compensates the uplink signal according to the uplink frequency offset and the uplink time offset, and compensates the downlink signal according to the downlink frequency offset. Through the above technical means, the frequency deviation is determined according to the deviation between the actual detection frequency of the synchronization signal block and the actual transmission frequency of the synchronization signal block, the satellite angle value range is determined according to the satellite motion state, the downlink frequency deviation and the satellite beam angle, the time deviation range is determined based on the satellite angle value range, and the uplink time deviation is determined in the time deviation range according to the random access method. Under the premise that the ground terminal is not equipped with a receiving module of the global navigation satellite system, the time and frequency deviation of the satellite-to-ground link can also be accurately estimated, effectively reducing the manufacturing cost and use cost of the ground terminal. The uplink and downlink signals are compensated based on the frequency deviation and time deviation range, which solves the problem that the time deviation and frequency deviation of the satellite-to-ground link affect the communication quality in the prior art, and improves the communication quality between the satellite base station and the terminal.

[0151] Based on the above embodiments, Fig.11 A schematic diagram of the structure of a time-frequency offset compensation device for a satellite-to-ground link provided in an embodiment of the present application. Fig.11 The time-frequency offset compensation device for the satellite-to-ground link provided in this embodiment specifically includes: a detection frequency point determination module 21, a frequency offset determination module 22, a satellite information determination module 23, a satellite angle determination module 24, a time offset determination module 25 and a time-frequency offset compensation module 26.

[0152] The detection frequency determination module 21 is configured to perform traversal detection on the synchronization signal block based on each first candidate frequency of the global synchronization channel number, and determine the actual detection frequency of the detected synchronization signal block;

[0153] The frequency deviation determination module 22 is configured to determine the actual transmission frequency for sending the synchronization signal block according to the synchronization signal block, determine the difference between the actual detection frequency and the actual transmission frequency as the downlink frequency deviation, and determine the uplink frequency deviation according to the downlink frequency deviation;

[0154] The satellite information determination module 23 is configured to obtain satellite ephemeris through the system information block indicated by the synchronization signal block, and determine the satellite position information and satellite speed information of the satellite according to the satellite ephemeris;

[0155] The satellite angle determination module 24 is configured to obtain the beam angle information of the satellite through the system information block, and determine the value range of the satellite angle according to the beam angle information, the downlink frequency deviation and the satellite speed information;

[0156] The time deviation determination module 25 is configured to determine a value range of the satellite-to-ground distance according to a value range of the satellite angle and satellite position information, determine a time deviation range according to the value range of the satellite-to-ground distance, and determine an uplink time deviation in the time deviation range according to a random access method;

[0157] The time-frequency offset compensation module 26 is configured to compensate the uplink signal according to the uplink frequency offset and the uplink time offset, and to compensate the downlink signal according to the downlink frequency offset.

[0158] Based on the above embodiment, the frequency deviation determination module 22 includes: an indication message acquisition unit, configured to obtain a main information block in the physical broadcast channel of the synchronization signal block, and obtain an indication message of the system information block in the main information block; a first transmission frequency determination unit, configured to detect the system information block on the initial bandwidth part according to the indication message, and obtain the actual transmission frequency used to send the synchronization signal block in the frequency field of the system information block.

[0159] On the basis of the above embodiment, the frequency deviation determination module 22 includes: an identification low-order acquisition unit, configured to determine the cell identification sequence through the primary synchronization signal and the secondary synchronization signal of the synchronization signal block, and obtain the low-order part of the cell identification sequence; a candidate frequency determination unit, configured to determine a candidate frequency set from the frequency points corresponding to multiple consecutive global synchronization channel numbers according to the global synchronization channel number of the actual detection frequency; a second transmission frequency determination unit, configured to determine a matching frequency point in the candidate frequency point set whose low-order part of the global synchronization channel number is the same as the cell identification sequence, and determine the matching frequency point as the actual transmission frequency point for sending the synchronization signal block.

[0160] On the basis of the above embodiment, the beam angle information includes the beam center angle and the beam width; accordingly, the satellite angle determination module 24 includes: an angle maximum value determination unit, configured to determine the sum of the beam center angle and half the beam width as the maximum value of the satellite angle, and determine the angle difference between the beam center angle and half the beam width; a complementary angle determination unit, configured to determine the projection angle according to the downlink frequency deviation and satellite speed information, and determine the complementary angle of the projection angle, where the projection angle is the angle between the satellite speed direction and the satellite-to-ground link; an angle minimum value determination unit, configured to determine the minimum value among the complementary angle, the angle difference and zero as the minimum value of the satellite angle.

[0161] On the basis of the above embodiment, the time deviation determination module 25 includes: a ratio determination unit, configured to determine a first ratio between the earth radius and the sine value of the maximum value of the satellite angle, and determine a second ratio between the earth radius and the sine value of the minimum value of the satellite angle; a terminal angle determination unit, configured to determine a first distance between the satellite and the center of the earth according to the satellite position information and the center of the earth position, determine the minimum value of the terminal angle according to the ratio of the first distance to the first ratio, and determine the maximum value of the terminal angle according to the ratio of the first distance to the second ratio; a geocentric angle determination unit, configured to determine the minimum value of the geocentric angle according to the maximum value of the terminal angle and the minimum value of the satellite angle, and determine the maximum value of the geocentric angle according to the minimum value of the terminal angle and the maximum value of the satellite angle; a satellite-to-ground distance determination unit, configured to determine the product of the sine value of the maximum value of the geocentric angle and the first ratio as the maximum value of the satellite-to-ground distance, and determine the product of the sine value of the minimum value of the geocentric angle and the second ratio as the minimum value of the satellite-to-ground distance.

[0162] On the basis of the above embodiment, the time deviation determination module 25 includes: a first signal sending unit, configured to determine an initial uplink timing advance according to a minimum value of the time deviation range, and send a random access signal based on the uplink timing advance; a timing advance adjustment unit, configured to increase the uplink timing advance according to the time length of the cyclic prefix of the random access signal when a random access response corresponding to the random access signal is not received within a preset time; a second signal sending unit, configured to resend the random access signal based on the increased uplink timing advance when the increased uplink timing advance is less than or equal to twice the maximum value of the time deviation range; a time deviation compensation unit, configured to adjust the uplink timing advance according to the first timing advance instruction in the random access response when a random access response corresponding to the random access signal is received within a preset time, and determine the uplink time deviation based on the adjusted uplink timing advance.

[0163] On the basis of the above embodiment, the time deviation determination module 25 also includes: a third signal sending unit, which is configured to, after increasing the uplink timing advance according to the time length of the cyclic prefix of the random access signal, adjust the uplink timing advance to twice the maximum value of the time deviation range when the increased uplink timing advance is greater than twice the maximum value of the time deviation range, and resend the random access signal based on the adjusted uplink timing advance.

[0164] As described above, the time-frequency offset compensation device for the satellite-to-ground link provided by the embodiment of the present application performs traversal detection on the synchronization signal block through each first candidate frequency point of the global synchronization channel number to determine the actual detection frequency point of the detected synchronization signal block; determines the actual transmission frequency point for sending the synchronization signal block according to the synchronization signal block, determines the difference between the actual detection frequency point and the actual transmission frequency point as the downlink frequency offset, and determines the uplink frequency offset according to the downlink frequency offset; obtains the satellite ephemeris through the system information block corresponding to the indication of the synchronization signal block, and determines the satellite position information and the satellite speed information according to the satellite ephemeris; obtains the beam angle information of the satellite through the system information block, and determines the value range of the satellite angle according to the beam angle information, the downlink frequency offset and the satellite speed information; determines the value range of the satellite-to-ground distance according to the value range of the satellite angle and the satellite position information, determines the time offset range according to the value range of the satellite-to-ground distance, and determines the uplink time offset in the time offset range according to the random access method; compensates the uplink signal according to the uplink frequency offset and the uplink time offset, and compensates the downlink signal according to the downlink frequency offset. Through the above technical means, the frequency deviation is determined according to the deviation between the actual detection frequency of the synchronization signal block and the actual transmission frequency of the synchronization signal block, the satellite angle value range is determined according to the satellite motion state, the downlink frequency deviation and the satellite beam angle, the time deviation range is determined based on the satellite angle value range, and the uplink time deviation is determined in the time deviation range according to the random access method. Under the premise that the ground terminal is not equipped with a receiving module of the global navigation satellite system, the time and frequency deviation of the satellite-to-ground link can also be accurately estimated, effectively reducing the manufacturing cost and use cost of the ground terminal. The uplink and downlink signals are compensated based on the frequency deviation and time deviation range, which solves the problem that the time deviation and frequency deviation of the satellite-to-ground link affect the communication quality in the prior art, and improves the communication quality between the satellite base station and the terminal.

[0165] The time-frequency offset compensation device for a satellite-to-ground link provided in an embodiment of the present application can be used to execute the time-frequency offset compensation method for a satellite-to-ground link provided in the above embodiment, and has corresponding functions and beneficial effects.

[0166] Fig.12 is a schematic diagram of the structure of a time-frequency offset compensation device for a satellite-to-ground link provided in an embodiment of the present application, with reference to Fig.12 The time-frequency offset compensation device of the satellite-to-ground link includes: a processor 31, a memory 32, a communication device 33, an input device 34, and an output device 35. The number of processors 31 in the time-frequency offset compensation device of the satellite-to-ground link can be one or more, and the number of memories 32 in the time-frequency offset compensation device of the satellite-to-ground link can be one or more. The processor 31, the memory 32, the communication device 33, the input device 34, and the output device 35 of the time-frequency offset compensation device of the satellite-to-ground link can be connected through a bus or other methods.

[0167] The memory 32, as a computer-readable storage medium, can be used to store software programs, computer executable programs and modules, such as program instructions / modules corresponding to the time-frequency offset compensation method of the satellite-to-ground link in any embodiment of the present application (for example, the detection frequency point determination module 21, the frequency offset determination module 22, the satellite information determination module 23, the satellite angle determination module 24, the time offset determination module 25 and the time-frequency offset compensation module 26 in the time-frequency offset compensation device of the satellite-to-ground link). The memory 32 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application required for at least one function; the data storage area may store data created according to the use of the device, etc. In addition, the memory 32 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some instances, the memory may further include a memory remotely arranged relative to the processor, and these remote memories may be connected to the device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0168] The communication device 33 is used for data transmission.

[0169] The processor 31 executes various functional applications and data processing of the device by running the software programs, instructions and modules stored in the memory 32, that is, implements the above-mentioned time-frequency offset compensation method of the satellite-to-ground link.

[0170] The input device 34 may be used to receive input digital or character information and generate key signal input related to user settings and function control of the device. The output device 35 may include a display device such as a display screen.

[0171] The time-frequency offset compensation device for the satellite-to-ground link provided above can be used to execute the time-frequency offset compensation method for the satellite-to-ground link provided in the above embodiment, and has corresponding functions and beneficial effects.

[0172] The embodiment of the present application also provides a storage medium containing computer executable instructions. When the computer executable instructions are executed by a computer processor, they are used to execute a method for compensating a satellite-to-ground link time-frequency offset. The satellite-to-ground link time-frequency offset compensation method includes: performing traversal detection on a synchronization signal block based on each first candidate frequency point of a global synchronization channel number to determine an actual detection frequency point at which the synchronization signal block is detected; determining an actual transmission frequency point for sending the synchronization signal block according to the synchronization signal block, determining a difference between the actual detection frequency point and the actual transmission frequency point as a downlink frequency offset, and determining an uplink frequency offset according to the downlink frequency offset; and determining an uplink frequency offset according to the downlink frequency offset by synchronizing the synchronization signal block. The system information block indicated by the signal block corresponds to obtain the satellite ephemeris, and determines the satellite position information and the satellite speed information according to the satellite ephemeris; obtains the beam angle information of the satellite through the system information block, and determines the value range of the satellite angle according to the beam angle information, the downlink frequency deviation and the satellite speed information; determines the value range of the satellite-to-earth distance according to the value range of the satellite angle and the satellite position information, determines the time deviation range according to the value range of the satellite-to-earth distance, and determines the uplink time deviation within the time deviation range according to the random access method; compensates the uplink signal according to the uplink frequency deviation and the uplink time deviation, and compensates the downlink signal according to the downlink frequency deviation.

[0173] Storage medium - any of various types of memory devices or storage devices. The term "storage medium" is intended to include: installation media, such as CD-ROM, floppy disk or tape device; computer system memory or random access memory, such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory, such as flash memory, magnetic media (such as hard disk or optical storage); registers or other similar types of memory elements, etc. Storage media may also include other types of memory or combinations thereof. In addition, the storage medium may be located in the first computer system in which the program is executed, or may be located in a different second computer system, which is connected to the first computer system via a network (such as the Internet). The second computer system can provide program instructions to the first computer for execution. The term "storage medium" may include two or more storage media residing in different locations (for example, in different computer systems connected by a network). The storage medium may store program instructions (for example, embodied as a computer program) that can be executed by one or more processors.

[0174] Of course, the storage medium containing computer executable instructions provided in an embodiment of the present application, whose computer executable instructions are not limited to the above-mentioned time-frequency offset compensation method for the satellite-to-ground link, can also execute the relevant operations in the time-frequency offset compensation method for the satellite-to-ground link provided in any embodiment of the present application.

[0175] The satellite-to-ground link time-frequency offset compensation device, storage medium, and satellite-to-ground link time-frequency offset compensation device provided in the above embodiments can execute the satellite-to-ground link time-frequency offset compensation method provided in any embodiment of the present application. For technical details not described in detail in the above embodiments, refer to the satellite-to-ground link time-frequency offset compensation method provided in any embodiment of the present application.

[0176] The above are only preferred embodiments of the present application and the technical principles used. The present application is not limited to the specific embodiments herein, and various obvious changes, readjustments and substitutions that can be made by those skilled in the art will not deviate from the protection scope of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the claims.

Claims

1. A method for compensating time-frequency offset of a satellite-to-ground link, characterized in that: Applied to ground terminals, including: Perform traversal detection on the synchronization signal block based on each first candidate frequency point of the global synchronization channel number, and determine the actual detection frequency point at which the synchronization signal block is detected; Determine an actual transmission frequency for sending the synchronization signal block according to the synchronization signal block, determine a difference between the actual detection frequency and the actual transmission frequency as a downlink frequency offset, and determine an uplink frequency offset according to the downlink frequency offset; Acquire satellite ephemeris through the system information block indicated by the synchronization signal block, and determine satellite position information and satellite speed information according to the satellite ephemeris; Acquire the beam angle information of the satellite through the system information block, and determine the value range of the satellite angle according to the beam angle information, the downlink frequency deviation and the satellite speed information; Determine a value range of a satellite-to-ground distance according to a value range of the satellite angle and the satellite position information, determine a time deviation range according to the value range of the satellite-to-ground distance, and determine an uplink time deviation in the time deviation range according to a random access method; An uplink signal is compensated according to the uplink frequency deviation and the uplink time deviation, and a downlink signal is compensated according to the downlink frequency deviation.

2. The method for compensating time-frequency offset of a satellite-to-ground link according to claim 1, characterized in that: The determining, according to the synchronization signal block, an actual transmission frequency for sending the synchronization signal block comprises: Acquire a master information block in a physical broadcast channel of the synchronization signal block, and acquire an indication message of a system information block in the master information block; The system information block is detected on the initial bandwidth part according to the indication message, and the actual transmission frequency used to send the synchronization signal block is obtained in the frequency field of the system information block.

3. The method for compensating time-frequency offset of a satellite-to-ground link according to claim 1, characterized in that: The determining, according to the synchronization signal block, an actual transmission frequency for sending the synchronization signal block comprises: Determine a cell identification sequence by using a primary synchronization signal and a secondary synchronization signal of the synchronization signal block, and obtain a low-order part of the cell identification sequence; According to the global synchronization channel number of the actually detected frequency point, determining a candidate frequency point set from frequency points corresponding to a plurality of consecutive global synchronization channel numbers; A matching frequency point whose low-order part of a global synchronization channel number is the same as the low-order part of the cell identification sequence is determined in the candidate frequency point set, and the matching frequency point is determined as the actual transmission frequency point for sending the synchronization signal block.

4. The method for compensating time-frequency offset of a satellite-to-ground link according to claim 1, characterized in that: The beam angle information includes a beam center angle and a beam width; accordingly, determining a value range of a satellite angle according to the beam angle information, the downlink frequency deviation and the satellite speed information includes: Determine the sum of the beam center angle and half of the beam width as the maximum value of the satellite angle, and determine the angle difference between the beam center angle and half of the beam width; Determine a projection angle according to the downlink frequency deviation and the satellite speed information, and determine a complementary angle of the projection angle, wherein the projection angle is an angle between the satellite speed direction and the satellite-to-ground link; The minimum value among the complementary angle, the angle difference and zero is determined as the minimum value of the satellite angle.

5. The method for compensating time-frequency offset of a satellite-to-ground link according to claim 1, characterized in that: Determining the value range of the satellite-to-earth distance according to the value range of the satellite angle and the satellite position information includes: Determine a first ratio between the radius of the earth and the sine value of the maximum value of the satellite angle, and determine a second ratio between the radius of the earth and the sine value of the minimum value of the satellite angle; Determine a first distance between the satellite and the center of the earth according to the satellite position information and the position of the center of the earth, determine a minimum value of a terminal angle according to a ratio of the first distance to the first ratio, and determine a maximum value of the terminal angle according to a ratio of the first distance to the second ratio; Determine the minimum value of the geocentric angle according to the maximum value of the terminal angle and the minimum value of the satellite angle, and determine the maximum value of the geocentric angle according to the minimum value of the terminal angle and the maximum value of the satellite angle; The product of the sine value of the maximum value of the geocentric angle and the first ratio is determined as the maximum value of the satellite-to-earth distance, and the product of the sine value of the minimum value of the geocentric angle and the second ratio is determined as the minimum value of the satellite-to-earth distance.

6. The method for compensating time-frequency offset of a satellite-to-ground link according to claim 1, characterized in that: The determining the uplink time deviation in the time deviation range according to the random access mode includes: Determining an initial uplink timing advance according to a minimum value of the time offset range, and sending a random access signal based on the uplink timing advance; If no random access response corresponding to the random access signal is received within a preset time, increasing the uplink timing advance according to the time length of the cyclic prefix of the random access signal; When the increased uplink timing advance is less than or equal to twice the maximum value of the time offset range, resending the random access signal based on the increased uplink timing advance; When a random access response corresponding to the random access signal is received within a preset time, the uplink timing advance is adjusted according to the first timing advance instruction in the random access response, and the adjusted uplink timing advance is determined as the uplink timing offset.

7. The method for compensating time-frequency offset of a satellite-to-ground link according to claim 6, characterized in that: After increasing the uplink timing advance according to the time length of the cyclic prefix of the random access signal, the method further includes: When the increased uplink timing advance is greater than twice the maximum value of the time offset range, the uplink timing advance is adjusted to twice the maximum value of the time offset range, and the random access signal is resent based on the adjusted uplink timing advance.

8. A time-frequency offset compensation device for a satellite-to-ground link, characterized in that: Applied to ground terminals, including: A detection frequency determination module is configured to perform traversal detection on the synchronization signal block based on each first candidate frequency of the global synchronization channel number, and determine an actual detection frequency at which the synchronization signal block is detected; a frequency deviation determination module, configured to determine an actual transmission frequency for sending the synchronization signal block according to the synchronization signal block, determine a difference between the actual detection frequency and the actual transmission frequency as a downlink frequency deviation, and determine an uplink frequency deviation according to the downlink frequency deviation; A satellite information determination module is configured to obtain satellite ephemeris through a system information block corresponding to the indication of the synchronization signal block, and determine satellite position information and satellite speed information according to the satellite ephemeris; A satellite angle determination module is configured to obtain the beam angle information of the satellite through the system information block, and determine the value range of the satellite angle according to the beam angle information, the downlink frequency deviation and the satellite speed information; A time deviation determination module is configured to determine a value range of a satellite-to-ground distance according to a value range of the satellite angle and the satellite position information, determine a time deviation range according to the value range of the satellite-to-ground distance, and determine an uplink time deviation in the time deviation range according to a random access method; The time-frequency offset compensation module is configured to compensate the uplink signal according to the uplink frequency offset and the uplink time offset, and to compensate the downlink signal according to the downlink frequency offset.

9. A time-frequency offset compensation device for a satellite-to-ground link, characterized in that: include: one or more processors; A memory storing one or more programs, when the one or more programs are executed by the one or more processors, enables the one or more processors to implement the time-frequency offset compensation method for the satellite-to-ground link as described in any one of claims 1-7.

10. A storage medium containing computer executable instructions, characterized in that: The computer executable instructions are used to execute the time-frequency offset compensation method for the satellite-to-ground link as described in any one of claims 1-7 when executed by a computer processor.

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