Uplink synchronization method and device, ground terminal, equipment, medium and program product

Abstract

The invention provides an uplink synchronization method and device, a ground terminal, equipment, a medium and a program product, and the uplink synchronization method comprises the steps: after initial downlink synchronization is completed, periodically receiving synchronization signal blocks, and measuring a downlink time offset measurement value corresponding to each synchronization signal block; extracting a crystal oscillator time offset component and a Doppler residual time offset component from the downlink time offset measurement value corresponding to the target synchronization signal block; before an uplink signal is sent, uplink residual time offset compensation is carried out based on a crystal oscillator time offset component and a Doppler residual time offset component. According to the scheme, the synchronization signal block is periodically received, and the downlink time offset measurement value of the synchronization signal block is split into the crystal oscillator time offset component and the Doppler residual time offset component, so that the uplink synchronization method can accurately identify timing errors of two different sources in real time on a terminal side, error accumulation is reduced, and the accuracy of the uplink synchronization is improved. And the time synchronization precision of the uplink synchronization method can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to an uplink synchronization method and device, a ground terminal, equipment, a medium and a program product. BACKGROUND

[0002] In a wireless communication system, the relative movement of the transceiver end will produce Doppler effect, resulting in frequency offset and time domain change (dynamic time offset) in the signal transmission process. The Doppler time offset is caused by the distance change of the signal propagation path, and its change rate depends on the relative motion speed; while the crystal oscillator time offset is caused by the frequency deviation of the local crystal oscillator of the transceiver end, which usually changes linearly with time. The traditional method mainly estimates and corrects the frequency offset caused by the Doppler effect in the medium and low speed scene. In the high speed scene (such as satellite communication, the satellite relative to the ground terminal speed can reach 7km / s), the Doppler effect will not only cause frequency offset, but also cause obvious time domain compression or stretching.

[0003] Most of the related technologies periodically receive ephemeris information through the terminal, and use the ephemeris prediction module to pre-compensate the uplink and downlink time offset between the two receiving gaps. However, since the downlink residual time offset measurement value cannot distinguish the Doppler residual time offset and the crystal oscillator time offset, the terminal can only compensate in a single direction when adjusting the uplink timing. This will cause the uplink timing to have double the Doppler or crystal oscillator time offset within one SSB period, and the error will accumulate with time, which may eventually cause the uplink to lose synchronization. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide an uplink synchronization method, device, ground terminal, equipment, medium and program product to solve the above problems.

[0005] In a first aspect, the embodiments of the present application provide an uplink synchronization method, which comprises: periodically receiving a synchronization signal block and measuring a downlink time offset measurement value corresponding to each synchronization signal block after completing initial downlink synchronization; extracting a crystal oscillator time offset component and a Doppler residual time offset component from the downlink time offset measurement value corresponding to a target synchronization signal block; and performing uplink residual time offset compensation based on the crystal oscillator time offset component and the Doppler residual time offset component before transmitting an uplink signal.

[0006] In the implementation process of the above scheme, by periodically receiving the synchronization signal block and splitting the downlink time offset measurement value into the crystal oscillator time offset component and the Doppler residual time offset component, the above uplink synchronization method can accurately identify the timing errors of two different sources in real time at the terminal side, reduce error accumulation, and improve the time synchronization accuracy of the above uplink synchronization method. On the other hand, the uplink residual time offset compensation can be completed before sending the uplink signal, so that the terminal can immediately correct the uplink sending time without waiting for additional network feedback or external calibration signals, thereby reducing synchronization delay and improving the real-time performance of the link and the throughput of the communication system. In another aspect, the above uplink synchronization method relies on local measurement and calculation of the terminal, which reduces the demand for high-precision hardware, simplifies the hardware design, reduces the cost of the terminal, and enhances the adaptability of the above uplink synchronization method to different environments, thereby improving the adaptability of the above uplink synchronization method.

[0007] In an implementation form of the first aspect, the extracting the crystal oscillator time offset component and the Doppler residual time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block comprises: determining a plurality of downlink time offset measurement values corresponding to the target synchronization signal block and a preset number of continuous synchronization signal blocks before the target synchronization signal block; determining a crystal oscillator time offset change rate of the crystal oscillator time offset component based on the plurality of downlink time offset measurement values; determining the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal oscillator time offset change rate; and determining the Doppler residual time offset component based on the downlink time offset measurement value and the crystal oscillator time offset component of the target synchronization signal block.

[0008] In the implementation process of the above scheme, based on the characteristic that the crystal oscillator time offset changes linearly with time, the crystal oscillator time offset change rate is determined by analyzing the downlink time offset measurement values of the target synchronization signal block and a plurality of synchronization signal blocks before the target synchronization signal block, the crystal oscillator time offset component corresponding to the target synchronization signal block can be accurately extracted, the separation of the crystal oscillator time offset and the Doppler residual time offset is more accurate, and the time synchronization accuracy of the above time synchronization method is improved. On the other hand, based on the crystal oscillator time offset change rate and the total downlink time offset measurement value of the target synchronization signal block, the Doppler residual time offset component corresponding to the target synchronization signal block can be accurately calculated, which provides an accurate basis for subsequent uplink compensation. In another aspect, the crystal oscillator time offset component and the Doppler residual component are extracted before sending the next synchronization signal block, and the uplink residual time offset compensation is performed, so that the above uplink synchronization method can compensate the uplink residual time offset in real time and efficiently, reduce the synchronization delay, and enhance the stability and reliability of the communication system.

[0009] In one implementation of the first aspect, determining the crystal oscillator time offset rate of change of the crystal oscillator time offset component based on a plurality of downlink time offset measurements includes: averaging the plurality of downlink time offset measurements to determine the crystal oscillator time offset rate of change of the crystal oscillator time offset component.

[0010] In the implementation of the above scheme, based on the zero-mean characteristic of Doppler residual time offset, averaging multiple downlink time offset measurements can effectively reduce the impact of Doppler residual time offset on crystal oscillator time offset, enabling the above uplink synchronization method to stably and accurately determine the crystal oscillator time offset change rate, thereby improving the time synchronization accuracy of the above uplink synchronization method; on the other hand, the averaging operation is simple and easy to implement, has low computational resource requirements, and can quickly obtain the crystal oscillator time offset change rate, which is beneficial to improving the real-time performance of the above uplink synchronization method.

[0011] In one implementation of the first aspect, determining the crystal oscillator time offset rate of change of the crystal oscillator time offset component based on multiple downlink time offset measurements includes: performing linear fitting on the multiple downlink time offset measurements to obtain a fitting relationship between the multiple downlink time offset measurements and time; and determining the crystal oscillator time offset rate of change of the crystal oscillator time offset component based on the slope in the fitting relationship.

[0012] In the implementation of the above scheme, by linearly fitting multiple downlink time offset measurements, the trend of time offset change over time can be clearly captured, thereby more accurately determining the crystal oscillator time offset change rate and avoiding interference from short-term fluctuations. On the other hand, the slope of the fitting relationship directly corresponds to the crystal oscillator time offset change rate. This calculation method based on a physical model not only improves the accuracy of determining the crystal oscillator time offset change rate but also enhances the interpretability of the results. Furthermore, linear fitting is a common mathematical tool that is easy to implement and computationally efficient, enabling it to run quickly on the terminal. This is beneficial for improving the timeliness and effectiveness of the uplink synchronization method for compensating for uplink residual time offset.

[0013] In one implementation of the first aspect, the method further includes: acquiring a target signal synchronization block at each interval of uplink compensation preset period.

[0014] In the implementation of the above scheme, the target signal synchronization block is acquired at each uplink compensation preset period to achieve periodic compensation for the uplink residual time offset. Each compensation can closely match the actual communication situation at the most recent time, which is beneficial to improving the time synchronization accuracy of the above uplink synchronization. On the one hand, this method of periodically acquiring the target signal synchronization block helps to detect and adapt to changes in the communication environment in a timely manner, which is beneficial to improving the adaptability and reliability of the above uplink synchronization method. On the other hand, by setting an appropriate preset period, a balance can be achieved between compensation accuracy and system resource consumption, so as to achieve timely compensation without increasing unnecessary resource overhead due to acquiring synchronization blocks too frequently.

[0015] In an implementation form of the first aspect, the determining the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal oscillator time offset change rate comprises: determining the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal oscillator time offset change rate and the uplink compensation preset period.

[0016] In the implementation process of the above scheme, the crystal oscillator time offset component is determined by combining the crystal oscillator time offset change rate and the uplink compensation preset period, which can more accurately match the actual needs of uplink compensation. This not only considers the long-term drift characteristics of the crystal oscillator, but also fits the periodicity of uplink compensation, which is conducive to improving the time synchronization accuracy of the above uplink synchronization method. On the other hand, adjusting the calculation of the crystal oscillator time offset component according to the preset period can ensure that the compensation action is consistent with the timing requirements of the communication system, thereby improving the communication efficiency. On the other hand, determining the crystal oscillator time offset component in combination with the preset period helps to maintain the consistency and stability of compensation under different environmental conditions, thereby improving the reliability of the compensation effect.

[0017] In an implementation form of the first aspect, the uplink residual time offset compensation based on the crystal oscillator time offset component is: compensating the crystal oscillator time offset component in the uplink residual time offset based on the crystal oscillator time offset component in the same direction as the time offset direction of the crystal oscillator time offset component. In the implementation process of the above scheme, the accumulated error caused by the crystal oscillator can be accurately corrected by compensating the crystal oscillator time offset component in its time offset direction, which can realize accurate alignment of the uplink sending time and effectively reduce the risk of out-of-sync caused by error accumulation. On the other hand, by compensating the crystal oscillator time offset component, the uplink can be more stable, which is conducive to improving the synchronization effect of the above uplink synchronization method.

[0018] In an implementation form of the first aspect, the uplink residual time offset compensation based on the Doppler residual time offset component is: compensating the Doppler residual time offset component in the uplink residual time offset based on the Doppler residual time offset component in the direction opposite to the time offset direction of the Doppler residual time offset component.

[0019] In the implementation process of the above scheme, by compensating the Doppler residual time offset component in the opposite direction, the time offset caused by the relative motion of the satellite can be effectively offset, so that the uplink signal is advanced or delayed to adapt to the path change, which is conducive to improving the adaptability of the above uplink synchronization method. On the other hand, by compensating the Doppler residual time offset component, the uplink can be more stable, which is conducive to improving the synchronization effect of the above uplink synchronization method.

[0020] Secondly, the application embodiment of the second aspect is an uplink synchronization device, which comprises: The downlink time offset measurement obtaining module is configured to periodically receive synchronization signal blocks and measure a downlink time offset measurement corresponding to each of the synchronization signal blocks after initial downlink synchronization is completed. The component extracting module is configured to extract a crystal oscillator time offset component and a Doppler residual time offset component from the downlink time offset measurement corresponding to the target synchronization signal block. The uplink compensation module is configured to perform uplink residual time offset compensation based on the crystal oscillator time offset component and the Doppler residual time offset component before an uplink signal is transmitted.

[0021] In a third aspect, an embodiment of the present application provides a ground terminal, including a baseband processor, wherein: The baseband processor is configured to periodically receive synchronization signal blocks and measure a downlink time offset measurement corresponding to each of the synchronization signal blocks after initial downlink synchronization is completed, extract a crystal oscillator time offset component and a Doppler residual time offset component from the downlink time offset measurement corresponding to the target synchronization signal block, and perform uplink residual time offset compensation based on the crystal oscillator time offset component and the Doppler residual time offset component before an uplink signal is transmitted.

[0022] In a fourth aspect, an embodiment of the present application provides an electronic device, including a processor, a memory, and a communication bus, wherein the processor and the memory complete communication with each other through the communication bus; the memory stores computer program instructions that can be executed by the processor, and when the computer program instructions are read and run by the processor, the method provided in the first aspect or any possible implementation manner of the first aspect is executed.

[0023] In a fifth aspect, an embodiment of the present application provides a computer readable storage medium, which stores computer program instructions, and when the computer program instructions are read and run by a processor, the method provided in the first aspect or any possible implementation manner of the first aspect is executed.

[0024] In a sixth aspect, an embodiment of the present application provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the method provided in the first aspect or any possible implementation manner of the first aspect is implemented.

[0025] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or be learned from the practice of the application. The purposes and other advantages of the present application can be realized and attained by the structure particularly pointed out in the written description, claims, and appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation to the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0027] Figure 1 The structure schematic diagram of the multi-beam mobile satellite communication system provided by the embodiments of the present application is shown in the figure. Figure 2 The flowchart of the uplink synchronization method provided by the embodiments of the present application is shown in the figure. Figure 3 The structure schematic diagram of the uplink synchronization device provided by the embodiments of the present application is shown in the figure. Figure 4 The structure schematic diagram of the electronic device provided by the embodiments of the present application is shown in the figure. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0029] The crystal oscillator time offset is the systematic offset of the respective crystal oscillators of the transmitting end and the receiving end due to the inconsistency of the nominal frequency. The offset is manifested as the difference between the absolute time identified by the receiving end and the actual sending time of the transmitting end, and is linearly accumulated with the duration of the communication. The change rate of the crystal oscillator time offset depends on the frequency difference of the crystal oscillators at both ends, and the change rate of the crystal oscillator time offset remains basically constant in the time scale of seconds, minutes or even hours, so the crystal oscillator time offset increases or decreases at an approximate uniform speed, and the direction and size depend on which end of the crystal oscillator has a higher frequency. Since the accumulation speed of the crystal oscillator time offset is stable, it can be identified by long-term statistical averaging and compensated separately, and will not change with the external propagation environment or relative motion.

[0030] Doppler effect refers to the phenomenon that when there is relative motion between a wave source and a receiving end, the frequency of the wave measured by the receiving end is different from the actual frequency of the wave emitted by the wave source. Generally, when the two are close to each other, the received frequency becomes higher; when the two are far away from each other, the received frequency becomes lower. In a low-speed communication scenario, the relative speed between the transmitter and the receiver is usually only tens to hundreds of kilometers per hour, and the Doppler shift is small, usually only tens of hertz to hundreds of hertz, which is much smaller than the carrier bandwidth. At this time, the stretching (time offset) in the time domain of the signal is very small and can be ignored in a symbol period, so the system only needs to compensate for the frequency offset to ensure the demodulation performance. In a high-speed scenario, such as in a low-orbit satellite communication scenario, the satellite relative to the ground terminal speed can reach 7 km / s, and the Doppler shift can reach tens of kilohertz or even higher, accompanied by significant dynamic time offset: the signal is compressed or stretched in the time domain, and a time domain offset of tens of nanoseconds or even more can be accumulated in a symbol period. This time offset changes rapidly with time, and if the method of only compensating for the frequency offset is still used, the inter-symbol interference and timing drift will quickly accumulate, resulting in demodulation failure. Therefore, in a high-speed scenario, both the frequency offset and the time offset need to be handled, and the traditional method of only compensating for the frequency offset is no longer applicable.

[0031] Therefore, the embodiment of the present application provides an uplink synchronization method, which can accurately identify the timing errors of two different sources in real time on the terminal side by periodically receiving a synchronization signal block and splitting the downlink time offset measurement value into a crystal oscillator time offset component and a Doppler residual time offset component, thereby reducing error accumulation and improving the time synchronization accuracy of the uplink synchronization method. On the other hand, the uplink residual time offset compensation can be completed before sending the uplink signal, so that the terminal can immediately correct the uplink sending time without waiting for additional network feedback or external calibration signals, thereby reducing synchronization delay and improving the real-time performance of the link and the throughput of the communication system. On the other hand, the uplink synchronization method relies on terminal local measurement and calculation, which reduces the demand for high-precision hardware, simplifies the hardware design, reduces the terminal cost, and enhances the adaptability of the uplink synchronization method to different environments, thereby improving the adaptability of the uplink synchronization method.

[0032] Before introducing the uplink synchronization method, the application scenario thereof is introduced. The technical solutions of the present application can be applied to a satellite communication system, a High Altitude Platform Station (HAPS) communication, and other Non-Terrestrial Network (NTN) systems, such as an Integrated Communication and Navigation (ICaN) system, a Global Navigation Satellite System (GNSS), and the like.

[0033] The satellite communication system can be integrated with a conventional mobile communication system. For example, the mobile communication system can be a 4th Generation (4G) communication system (e.g., a Long Term Evolution (LTE) system), a Worldwide Interoperability for Microwave Access (WiMAX) communication system, a 5th Generation (5G) communication system (e.g., a New Radio (NR) system), and a future mobile communication system, and the like.

[0034] Please refer to Figure 1 , Figure 1 is a schematic diagram of a multi-beam mobile satellite communication system suitable for embodiments of the present application. As shown in Figure 1 , the satellite provides communication services to terminal devices through multiple beams. The satellite in this scenario is a non-geostationary earth orbit (NGEO) satellite, and the satellite is connected to a core network device. The satellite covers the service area using multiple beams, and different beams can communicate through one or more of time division, frequency division, and space division. The satellite provides communication and navigation services to terminal devices through broadcast communication signals and navigation signals. The satellite mentioned in the embodiments of the present application can also be a satellite base station or a network side device carried on a satellite.

[0035] For example, according to the orbital height of the satellite, the satellite communication system can be divided into three types as follows: a geostationary earth orbit (GEO) satellite communication system, also known as a synchronous orbit satellite communication system; a medium earth orbit (MEO) satellite communication system; and a low earth orbit (LEO) satellite communication system. Among them, the GEO satellite orbit height is 35786km. The main advantage of the GEO satellite is that it can remain relatively stationary on the ground and provide a large coverage area. However, the GEO satellite communication also has obvious disadvantages: the GEO satellite orbit is far away from the earth, the free space propagation loss is large, which causes the communication link budget to be tight, and in order to increase the transmission or reception gain, a large-diameter antenna needs to be provided for the satellite; the GEO communication transmission delay is large, which can reach about 500ms round-trip delay, and cannot meet the demand of low-delay services; the GEO orbit resource is relatively tight, the launch cost is high, and the coverage cannot be provided for the two polar regions of the earth. The MEO satellite orbit height is in the range of 2000-35786km. The advantage is that global coverage can be achieved by using a relatively small number of satellites. However, the orbit height of the MEO satellite is higher than that of the LEO satellite, and the communication transmission delay is still large compared with the LEO satellite. The orbit height of the LEO satellite is in the range of 300-2000km. The LEO satellite has the advantages of small data propagation delay, small transmission loss, and low launch cost compared with the MEO and GEO orbit heights. Of course, in some specific application scenarios, the LEO satellite can be replaced by the GEO satellite or the MEO satellite, or even a combination of multiple types of satellites.

[0036] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0037] Please refer to Figure 2 The embodiment of the present application provides an uplink synchronization method, comprising: Step S110: After completing the initial downlink synchronization, periodically receive the synchronization signal block and measure the downlink time offset measurement value corresponding to each synchronization signal block. The above-mentioned synchronization signal block SSB (Synchronization Signal Block) is a key signal structure for initial access, time synchronization and frequency synchronization in wireless communication systems (such as 5G NR and satellite communication), mainly composed of primary synchronization signal (PSS), secondary synchronization signal (SSS) and physical broadcast channel (PBCH). Among them, the primary synchronization signal PSS is mainly used for the initial time synchronization and frequency synchronization of the terminal, helping the terminal to determine the time slot structure of the signal and part of the cell identity. The secondary synchronization signal SSS is mainly used in combination with the PSS for complete cell identity recognition and frame synchronization, providing a more accurate time reference. The physical broadcast channel PBCH carries key system information (such as broadcast messages, cell configuration parameters, etc.), and the terminal needs to demodulate PBCH to obtain basic communication parameters. In addition, SSB is generally repeated according to a fixed period (such as 5ms, 10ms, 20ms, 40ms, 80ms or 160ms in 5G NR), so as to ensure that the terminal can access the network at any time.

[0038] The above-mentioned initial downlink synchronization is a key step for the terminal to establish communication, and its main steps include: Step one, blind detection of SSB, mainly including: Scan SSB time slots: After the terminal is turned on, according to the SSB period (such as 5ms, 10ms, etc. in 5G NR) and time slot structure specified by the protocol, scan the possible SSB position. Since the terminal has no information about the time and frequency of the network at this time, it needs to perform blind detection on multiple time slots and frequency points.

[0039] Detect PSS: During the scanning process, the terminal first detects PSS. PSS has a clear time domain and frequency domain structure, and the terminal identifies the characteristic waveform of PSS through matching filtering or correlation operation, thereby obtaining preliminary time synchronization information (such as time slot boundary).

[0040] Detect SSS: After detecting PSS, the terminal further detects SSS according to the position of PSS. SSS carries cell identity information and part of the system parameters, helping the terminal to determine the specific cell identity and frame structure.

[0041] Demodulate PBCH: After detecting PSS and SSS, the terminal demodulates PBCH using demodulation reference signal (DM-RS). PBCH contains key system information, such as broadcast messages, cell configuration parameters, system frame number (SFN), etc.

[0042] Step two, initial downlink synchronization, mainly including: Time synchronization: By detecting PSS and SSS, the terminal determines the position of SSB in the time domain, thereby obtaining the time reference of the downlink. This includes information of the slot boundary and frame boundary, enabling the terminal to correctly demodulate subsequent downlink signals.

[0043] Frequency synchronization: The terminal uses the frequency domain characteristics of PSS and SSS to calibrate the frequency of the local oscillator, eliminating the effects of Doppler frequency offset and crystal frequency offset, thereby achieving frequency synchronization.

[0044] Cell access: The terminal obtains the basic configuration and broadcast message of the cell according to the demodulated PBCH information, and completes the initial access to the target cell.

[0045] Step three, time offset pre-compensation, mainly includes: After obtaining the initial downlink synchronization, the terminal periodically receives the satellite broadcast ephemeris information. The ephemeris information contains parameters such as the position, velocity and time of the satellite. The terminal uses these information to predict the Doppler time offset and pre-compensate, reducing the impact of Doppler effect.

[0046] After performing time offset pre-compensation, the terminal can continue to measure the downlink time offset value of SSB in the subsequent SSB period. The downlink time offset measurement value mainly includes the Doppler residual time offset and the crystal time offset.

[0047] It can be understood that the above initial downlink synchronization process is a relatively mature known technology in the art. For more specific implementation of initial downlink synchronization, please refer to related technologies. The embodiments of the present application will not be repeated.

[0048] Step S120: Extracting the crystal time offset component and the Doppler residual time offset component from the downlink time offset measurement value corresponding to the target synchronization signal block.

[0049] Optionally, the above step S120 can include: determining a plurality of downlink time offset measurement values corresponding to the target synchronization signal block and a preset number of continuous synchronization signal blocks located before the target synchronization signal block; determining a crystal time offset change rate of the crystal time offset component based on the plurality of downlink time offset measurement values; determining the crystal time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal time offset change rate; and determining the Doppler residual time offset component based on the downlink time offset measurement value of the target synchronization signal block and the crystal time offset component.

[0050] The crystal time offset change rate refers to the cumulative time offset amount of the crystal time offset per unit time. It can be understood that the crystal time offset is mainly caused by the frequency deviation of the crystal oscillator between the transmitting end and the receiving end, and usually changes linearly with time, which makes the crystal time offset change rate reflect the long-term trend of the crystal time offset. Based on the crystal time offset change rate, the corresponding crystal time offset component can be calculated in combination with the time position of the target synchronization signal block.

[0051] The above scheme is based on the characteristic that the crystal oscillator time offset changes linearly with time, determines the crystal oscillator time offset change rate by analyzing the downlink time offset measurement values of the target synchronization signal block and multiple synchronization signal blocks before the target synchronization signal block, accurately extracts the crystal oscillator time offset component corresponding to the target synchronization signal block, makes the separation of the crystal oscillator time offset and the Doppler residual time offset more accurate, and is beneficial to improving the time synchronization precision of the above time synchronization method; on the other hand, based on the crystal oscillator time offset change rate and the total downlink time offset measurement value of the target synchronization signal block, the Doppler residual time offset component corresponding to the target synchronization signal block can be accurately calculated, which provides an accurate basis for subsequent uplink compensation; on the other hand, the crystal oscillator time offset component and the Doppler residual component are extracted before sending the next synchronization signal block, and uplink residual time offset compensation is performed, so that the above uplink synchronization method can compensate the uplink residual time offset in real time and efficiently, reduce synchronization delay, and enhance the stability and reliability of the communication system.

[0052] The crystal oscillator time offset change rate of the crystal oscillator time offset component can be obtained by one or more of the following methods: First implementation: obtaining based on averaging; Optionally, the crystal oscillator time offset change rate of the crystal oscillator time offset component is determined based on the multiple downlink time offset measurement values, including: performing an averaging operation on the multiple downlink time offset measurement values to determine the crystal oscillator time offset change rate of the crystal oscillator time offset component. For example, the implementation includes:

[0053] Wherein, is the crystal oscillator time offset change rate of the crystal oscillator time offset component; is the number of downlink time offset measurement values participating in the calculation of the crystal oscillator time offset change rate; is the th downlink time offset measurement value in the downlink time offset measurement values, in seconds; is the SSB period, in seconds.

[0054] It can be understood that since the Doppler residual time offset is random and has the characteristic of zero mean, in the multiple downlink time offset measurement values, these random Doppler residual time offsets can cancel each other out. The averaging operation can smooth out these short-term random fluctuations, making the long-term trend of the crystal oscillator time offset more obvious, so as to more accurately determine the crystal oscillator time offset change rate.

[0055] The above scheme is based on the zero mean characteristic of the Doppler residual time offset, and by averaging a plurality of downlink time offset measurement values, the influence of the Doppler residual time offset on the crystal oscillator time offset can be effectively reduced, so that the above uplink synchronization method can stably and accurately determine the crystal oscillator time offset rate, thereby improving the time synchronization accuracy of the above uplink synchronization method. On the other hand, the averaging operation is simple to implement and has low demand for computing resources, and the crystal oscillator time offset rate can be quickly obtained, which is beneficial to improve the real-time performance of the above uplink synchronization method.

[0056] Second implementation: linear fitting based method is used to obtain the crystal oscillator time offset rate; Optionally, the crystal oscillator time offset rate of the crystal oscillator time offset component is determined based on the plurality of downlink time offset measurement values, including: performing linear fitting on the plurality of downlink time offset measurement values to obtain a fitting relationship of the plurality of downlink time offset measurement values with respect to time; and determining the crystal oscillator time offset rate of the crystal oscillator time offset component based on a slope in the fitting relationship.

[0057] It can be understood that the crystal oscillator time offset is linearly accumulated, and the Doppler residual time offset is randomly fluctuated with zero mean. The downlink time offset measurement values of a group of continuous synchronization signal blocks are approximated using a straight line. Since the random component (i.e. the Doppler residual component) is statistically positive and negative, the slope of the straight line is mainly determined by the linear component. The linear component in the downlink time offset measurement value is the crystal oscillator time offset component. Therefore, the slope of the straight line is the crystal oscillator time offset rate.

[0058] The above scheme can clearly capture the trend of the time offset with respect to time by linearly fitting the plurality of downlink time offset measurement values, thereby more accurately determining the crystal oscillator time offset rate and avoiding the interference of short-term fluctuations. On the other hand, the slope of the fitting relationship directly corresponds to the crystal oscillator time offset rate. This calculation method based on the physical model not only improves the determination accuracy of the crystal oscillator time offset rate, but also enhances the interpretability of the result. On the other hand, linear fitting is a common mathematical tool, which is easy to implement and has high computational efficiency, and can be quickly run on the terminal, which is beneficial to improve the timeliness and effectiveness of the uplink synchronization method for compensating the uplink residual time offset.

[0059] Third implementation: Kalman filter is used to obtain the crystal oscillator time offset rate; The state space model is used to dynamically estimate the crystal oscillator time offset and its rate, and the system model (such as the linear change model of the crystal oscillator time offset) and the observation data (the downlink time offset measurement value) are combined to recursively estimate the crystal oscillator time offset rate.

[0060] Fourth implementation: machine learning is used to obtain the crystal oscillator time offset rate; A machine learning algorithm (such as linear regression, support vector regression, random forest regression, etc.) is used to model the time offset measurement value to predict the crystal oscillator time offset rate.

[0061] The following describes the acquisition occasion of the target synchronization signal block in the above scheme, i.e., the triggering occasion of the uplink residual time offset compensation: The above scheme can trigger the uplink residual time offset compensation in at least two ways as follows: The first way: triggering the uplink residual time offset compensation once for each received SSB; After the terminal successfully receives and measures the downlink time offset of any SSB each time, the SSB is immediately regarded as a "target synchronization signal block", and then the crystal oscillator time offset component and the Doppler residual time offset component are extracted and the uplink residual time offset compensation is performed once. This block-by-block compensation mode compresses the update interval to a single SSB period (such as 5 ms, 10 ms, etc.), which is suitable for high-speed mobile or rapidly changing channel scenarios, and can control the residual error within the minimum range.

[0062] The second way: triggering the uplink residual time offset compensation according to the uplink compensation preset period; Optionally, the above uplink synchronization method further includes: acquiring the target signal synchronization block every interval of the uplink compensation preset period.

[0063] The terminal internally sets a relatively long fixed period, and when the period is counted, the terminal selects one of the most recently received SSBs as a "target synchronization signal block" and performs the uplink residual time offset compensation once. This period compensation mode reduces the calculation and signaling overhead, and is more suitable for terminals with relatively stable channels or limited power consumption. In addition, it can be understood that in a communication system, the basic unit of time is the number of SSBs, so the uplink compensation preset period can be represented by the number of SSBs, and the time length of the uplink compensation preset period can also be an integer multiple of the SSB period. In addition, it should be pointed out that since the crystal oscillator time offset change rate is a slowly drifting straight line, and the Doppler residual time offset is a noise that fluctuates rapidly around zero mean. Only when the observation window is long enough, the positive and negative fluctuations of the noise can be statistically offset, and the crystal oscillator time offset change rate can be highlighted from the noise. If the sample length is too short, the random fluctuation has not been averaged out, and the calculated crystal oscillator time offset change rate will be contaminated by noise, resulting in that the Doppler residual time offset is mistaken for the crystal oscillator time offset, and then a systematic bias is introduced in the uplink compensation. Therefore, sufficient continuous data can be collected first to average the random component sufficiently, and then the real change rate of the crystal oscillator time offset can be reliably extracted, and the subsequent residual time offset compensation will not amplify the error. For example: after the terminal is started or cold started for the first time, continuous downlink time offset measurement values not less than 10 seconds can be collected, and then the first uplink residual time offset compensation is performed. The initialization stage ensures that the crystal oscillator time offset change rate estimation has sufficient samples, and avoids amplification of early compensation errors; the subsequent compensation can operate normally according to the two triggering mechanisms of SSB by SSB or uplink compensation preset period.

[0064] The above scheme realizes periodic compensation for the uplink residual time offset by acquiring the target signal synchronization block every preset interval of uplink compensation, and each compensation can be close to the actual communication situation at the nearest time, which is beneficial to improve the time synchronization precision of the above uplink synchronization. On the one hand, this way of periodically acquiring the target signal synchronization block is helpful to timely discover and adapt to the change of the communication environment, and is beneficial to improve the adaptability and reliability of the above uplink synchronization method. On the other hand, by setting a suitable preset period, a balance between compensation precision and system resource consumption can be achieved, that is, the timeliness of compensation can be realized, and unnecessary resource overhead will not be increased due to too frequent acquisition of the synchronization block.

[0065] Optionally, the determination of the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal oscillator time offset change rate comprises: determining the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal oscillator time offset change rate and the preset interval of uplink compensation. For example, in an embodiment of the present application, the determination of the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal oscillator time offset change rate comprises: When the number of SSBs corresponding to the preset interval of uplink compensation is , the crystal oscillator time offset component in the downlink time offset cumulative value between the th SSB and the th SSB is calculated as follows: and the Doppler residual time offset component .

[0066]

[0067] , wherein is the crystal oscillator time offset component; is the crystal oscillator time offset change rate; is the SSB period; represents the interval between two uplink residual time offset compensations, represents the crystal oscillator time offset cumulative amount between the last uplink residual time offset compensation and the present uplink residual time offset compensation, that is, the crystal oscillator time offset component in ; represents the downlink time offset cumulative value between two uplink residual time offset compensations; is the Doppler residual time offset component; it can be understood that in the mechanism of SSB-by-SSB triggered compensation, .

[0068] In addition, it should be pointed out that when the first uplink residual time offset compensation is performed, the above crystal oscillator time offset component should also be calculated based on the selected number of samples, and the calculation of the crystal oscillator time offset component should also aim at the crystal oscillator time offset cumulative amount from the last uplink residual time offset compensation to the present uplink residual time offset compensation.

[0069] The above scheme can more accurately match the actual needs of uplink compensation by combining the crystal oscillator time offset change rate with the uplink compensation preset period, which not only considers the long-term drift characteristics of the crystal oscillator, but also fits the periodicity of the uplink compensation, thereby improving the time synchronization accuracy of the above uplink synchronization method; on the other hand, adjusting the calculation of the crystal oscillator time offset component according to the preset period can ensure that the compensation action is consistent with the timing requirements of the communication system, thereby improving the communication efficiency; on the other hand, determining the crystal oscillator time offset component in combination with the preset period can help maintain the consistency and stability of the compensation under different environmental conditions, thereby improving the reliability of the compensation effect.

[0070] Step S130: Before sending the uplink signal, performing uplink residual time offset compensation based on the crystal oscillator time offset component and the Doppler residual time offset component.

[0071] Optionally, the uplink residual time offset compensation based on the crystal oscillator time offset component in the above step S130 can be: based on the crystal oscillator time offset component, performing uplink residual time offset compensation on the crystal oscillator time offset component in the same direction as the time offset direction of the crystal oscillator time offset component. For example, when performing uplink residual time offset compensation at the first SSB moment, the uplink crystal oscillator time offset is compensated by , and the uplink Doppler residual time offset is compensated by .

[0072] The crystal oscillator time offset is caused by the frequency deviation of the transceiver's crystal oscillator, which is manifested as clock drift and accumulates linearly over time. For example, if the terminal crystal oscillator frequency is slightly lower than the satellite crystal oscillator, the terminal local clock will gradually lag behind the satellite clock. Since the influence of the crystal oscillator time offset on the uplink and downlink is consistent, the uplink needs to compensate in the same direction as the downlink measurement. If the downlink measurement shows that the crystal oscillator time offset is (the terminal lags), then when sending the uplink, the terminal needs to postpone the sending time to ensure that the uplink signal arrives at the satellite at the expected time.

[0073] The above scheme can accurately correct the cumulative error caused by the crystal oscillator by compensating the crystal oscillator time offset component in its time offset direction, accurately align the uplink sending time, and effectively reduce the risk of out-of-sync caused by error accumulation; on the other hand, by compensating the crystal oscillator time offset component, the uplink can be more stable, which is conducive to improving the synchronization effect of the above uplink synchronization method.

[0074] Optionally, the uplink residual time offset compensation based on the Doppler residual time offset component in the above step S130 can be: based on the Doppler residual time offset component, performing uplink residual time offset compensation on the Doppler residual time offset component in the direction opposite to the time offset direction of the Doppler residual time offset component.​

[0075] Doppler residual time bias is caused by the relative motion between satellite and terminal, which leads to the change of path time delay in the process of signal transmission. For example, if the satellite is far away from the terminal, the signal propagation time delay increases, and the downlink received signal lags behind. The influence of Doppler time bias on uplink and downlink is opposite. In downlink, the Doppler time bias measured by the terminal is positive (lag), which means that the signal arrival time is later than expected. However, in uplink, in order to offset the path change, the terminal needs to send the signal in advance, so the compensation direction is opposite to the direction of Doppler time bias. If the Doppler residual time bias is (lag), the uplink needs to send in advance to ensure that the signal arrives at the satellite on time. For another example, if the satellite is close to the terminal, the signal propagation path length is shortened, the propagation time delay is reduced, and the downlink received signal is advanced. The influence of Doppler time bias on uplink and downlink is opposite. In downlink, the Doppler time bias measured by the terminal is negative (advance), which means that the signal arrival time is earlier than expected; but in uplink, in order to offset the path change, the terminal needs to delay sending the signal, so the compensation direction is opposite to the direction of Doppler time bias. If the Doppler residual time bias is (advance), the uplink needs to delay sending to ensure that the signal arrives at the satellite on time.

[0076] The above scheme can effectively offset the time bias caused by the relative motion of the satellite by compensating the Doppler residual time bias component in the opposite direction, so as to make the uplink signal advance or delay to adapt to the path change, which is beneficial to improve the adaptability of the above uplink synchronization method; on the other hand, by compensating the Doppler residual time bias component, the uplink can be more stable, which is beneficial to improve the synchronization effect of the above uplink synchronization method.

[0077] Please refer to Figure 3 , based on the same inventive concept, the embodiment of the present application also provides an uplink synchronization device 200, comprising: a downlink time bias measurement value acquisition module 210, configured to periodically receive a synchronization signal block and measure a downlink time bias measurement value corresponding to each of the synchronization signal block after completing initial downlink synchronization; a component extraction module 220, configured to extract a crystal oscillator time bias component and a Doppler residual time bias component from the downlink time bias measurement value corresponding to the target synchronization signal block; an uplink compensation module 230, configured to perform uplink residual time bias compensation based on the crystal oscillator time bias component and the Doppler residual time bias component before sending the uplink signal.

[0078] Optionally, the component extraction module 220 is specifically configured to: determine a plurality of downlink time offset measurement values corresponding to a target synchronization signal block and a preset number of continuous synchronization signal blocks located before the target synchronization signal block; determine a crystal oscillator time offset change rate of the crystal oscillator time offset component based on the plurality of downlink time offset measurement values; determine the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal oscillator time offset change rate; and determine a Doppler residual time offset component based on the downlink time offset measurement value and the crystal oscillator time offset component of the target synchronization signal block.

[0079] Optionally, the component extraction module 220 is specifically configured to: perform an averaging operation on the plurality of downlink time offset measurement values to determine the crystal oscillator time offset change rate of the crystal oscillator time offset component.

[0080] Optionally, the component extraction module 220 is specifically configured to: perform linear fitting on the plurality of downlink time offset measurement values to obtain a fitting relationship of the plurality of downlink time offset measurement values with respect to time; and determine the crystal oscillator time offset change rate of the crystal oscillator time offset component based on a slope in the fitting relationship.

[0081] Optionally, the component extraction module 220 is specifically configured to: obtain a target signal synchronization block every uplink compensation preset period.

[0082] Optionally, the component extraction module 220 is specifically configured to: determine the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal oscillator time offset change rate and the uplink compensation preset period.

[0083] Optionally, the uplink compensation module 230 is specifically configured to: perform uplink residual time offset compensation on the crystal oscillator time offset component in a same direction as a time offset direction of the crystal oscillator time offset component based on the crystal oscillator time offset component; and perform the uplink residual time offset compensation on the Doppler residual time offset component in a direction opposite to a time offset direction of the Doppler residual time offset component based on the Doppler residual time offset component.

[0084] Based on the same inventive concept, the embodiments of the present application also provide a ground terminal, comprising a baseband processor, wherein: The baseband processor is configured to: periodically receive synchronization signal blocks and measure downlink time offset measurement values corresponding to each of the synchronization signal blocks after completing initial downlink synchronization; extract a crystal oscillator time offset component and a Doppler residual time offset component from the downlink time offset measurement value corresponding to a target synchronization signal block; and perform uplink residual time offset compensation based on the crystal oscillator time offset component and the Doppler residual time offset component before transmitting an uplink signal.

[0085] Figure 4A schematic diagram of an electronic device is provided for the embodiments of the present application. Refer to Figure 4 The electronic device 300 includes a processor 310, a memory 320, and a communication interface 330, which are interconnected and communicate with each other through a communication bus 340 and / or other forms of connection mechanism (not shown).

[0086] The memory 320 includes one or more (only one is shown in the figure), which can be, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc. The processor 310 and other possible components can access, read and / or write data in the memory 320.

[0087] The processor 310 includes one or more (only one is shown in the figure), which can be an integrated circuit chip with signal processing capability. The above-mentioned processor 310 can be a general-purpose processor, including a central processing unit (CPU), a micro controller unit (MCU), a network processor (NP) or other conventional processors; it can also be a special-purpose processor, including a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0088] The communication interface 330 includes one or more (only one is shown in the figure), which can be used for direct or indirect communication with other devices to interact with data. For example, the communication interface 330 can be an Ethernet interface; it can be a mobile communication network interface, such as a 3G, 4G, 5G network interface; or it can be other types of interfaces with data transceiver function.

[0089] One or more computer program instructions can be stored in the memory 320, and the processor 310 can read and run the computer program instructions to implement the uplink synchronization method provided by the embodiments of the present application and other desired functions.

[0090] It can be understood that, Figure 4 The structure shown is only schematic, and the electronic device 300 can further include more or fewer components than those shown in the figures, or have a different configuration from that shown in the figures. Figure 4 The components shown in the figures can be implemented in hardware, software, or a combination thereof. For example, the electronic device 300 can be a single server (or other device with computing processing capability), a combination of multiple servers, a cluster of a large number of servers, etc., and can be a physical device or a virtual device. Figure 4 Figure 4 As an implementation manner, the electronic device 300 described above can be a terminal, and different terminals can be connected to each other in a wired or wireless manner. The terminal can be widely applied to various scenarios, such as Near Field Communications (NFC) Device-to-Device (D2D), Vehicle to Everything (V2X) communication, Machine-type Communication (MTC), Internet of Things (IOT), virtual reality, augmented reality, industrial control, autonomous driving, remote medical treatment, smart power grid, smart furniture, smart office, smart wear, smart transportation, smart city, etc.

[0091] As an implementation manner, the electronic device 300 described above can be a terminal, and different terminals can be connected to each other in a wired or wireless manner. The terminal can be widely applied to various scenarios, such as Near Field Communications (NFC) Device-to-Device (D2D), Vehicle to Everything (V2X) communication, Machine-type Communication (MTC), Internet of Things (IOT), virtual reality, augmented reality, industrial control, autonomous driving, remote medical treatment, smart power grid, smart furniture, smart office, smart wear, smart transportation, smart city, etc.

[0092] ​The terminal can also be referred to as a mobile station (MS), a terminal, terminal equipment, and can also include a subscriber unit, a cellular phone, a smart phone, a wireless data card, a personal digital assistant (PDA) computer, a tablet computer, a wireless modem, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a machine type communication (MTC) terminal, and the like. For ease of description, all the above-mentioned devices are collectively referred to as a terminal in all the embodiments of the present application.

[0093] The foregoing terminal can further include an antenna and a transceiver. The transceiver adjusts (for example, analog conversion, filtering, amplification, and up-conversion) output samples and generates an uplink signal, which is transmitted to a network device via the antenna; on the downlink, the antenna receives a downlink signal transmitted by the network device, and the transceiver adjusts (for example, filtering, amplification, down-conversion, and digitization) the signal received from the antenna and provides input samples. The processor 310 is configured to perform the uplink synchronization method described in the above embodiments. The embodiments of the present application do not limit the specific technology and specific device form adopted by the terminal.

[0094] The embodiments of the present application further provide a computer-readable storage medium having computer program instructions stored thereon, and the computer program instructions are read and executed by a processor of a computer to perform the uplink synchronization method provided by the embodiments of the present application. For example, the computer-readable storage medium can be implemented as Figure 4 a memory 320 in the electronic device 300.

[0095] The embodiments of the present application further provide a computer program product, which includes a computer program, and the computer program is executed by a processor to implement the uplink synchronization method provided by the embodiments of the present application.

[0096] In the embodiments of the present application, it should be understood that the disclosed apparatus and method can be implemented in other manners. The embodiments described above are merely exemplary, for example, the division of the units is only a logical function division, and there can be another division manner in actual implementation; for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0097] In addition, the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments of the present application.

[0098] In addition, the functional modules in the various embodiments of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0099] It should be noted that if the functions are realized in the form of software function modules and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the parts that make contributions to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0100] In this document, the terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations.

[0101] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the description and claims of this application as well as the above discussion of the background of the application, provide examples of the technical features of the application. The terms "comprises," "comprising," "includes," "including" and "has," "having" as used herein, are intended to be interpreted as specifying the presence of the stated features but not precluding the presence of one or more other features.

[0102] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0103] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive or alternative embodiments. It is expressly understood that the embodiments described herein are merely examples and that a person skilled in the art will be able to devise other embodiments that, although not explicitly described herein, fall within the framework of the present application.

[0104] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects.

[0105] The above only describes the embodiments of the present application and is not used to limit the protection scope of the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An uplink synchronization method, characterized by, The method comprises: After completing initial downlink synchronization, periodically receiving a synchronization signal block and measuring a downlink time offset measurement value corresponding to each synchronization signal block; Extracting a crystal oscillator time offset component and a Doppler residual time offset component from the downlink time offset measurement value corresponding to the target synchronization signal block; Before sending an uplink signal, performing uplink residual time offset compensation based on the crystal oscillator time offset component and the Doppler residual time offset component.

2. The uplink synchronization method of claim 1, wherein, The extracting a crystal oscillator time offset component and a Doppler residual time offset component from the downlink time offset measurement value corresponding to the target synchronization signal block comprises: Determining a plurality of downlink time offset measurement values corresponding to a target synchronization signal block and a preset number of continuous synchronization signal blocks located before the target synchronization signal block; Based on a plurality of downlink time offset measurement values, determining a crystal oscillator time offset change rate of the crystal oscillator time offset component; Based on the crystal oscillator time offset change rate, determining the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block; Based on the downlink time offset measurement value of the target synchronization signal block and the crystal oscillator time offset component, determining a Doppler residual time offset component.

3. The uplink synchronization method of claim 2, wherein, The determining a crystal oscillator time offset change rate of the crystal oscillator time offset component based on a plurality of downlink time offset measurement values comprises: Performing an averaging operation on a plurality of downlink time offset measurement values to determine a crystal oscillator time offset change rate of the crystal oscillator time offset component.

4. The uplink synchronization method of claim 2, wherein, The determining a crystal oscillator time offset change rate of the crystal oscillator time offset component based on a plurality of downlink time offset measurement values comprises: Performing linear fitting on a plurality of downlink time offset measurement values to obtain a fitting relationship of a plurality of downlink time offset measurement values with respect to time; Based on the slope in the fitting relationship, determining a crystal oscillator time offset change rate of the crystal oscillator time offset component.

5. The uplink synchronization method of claim 2, wherein, The method further comprises: Every interval uplink compensation preset period, obtaining a target signal synchronization block.

6. The uplink synchronization method of claim 5, wherein, The determining the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block based on the crystal oscillator time offset change rate comprises: Based on the crystal oscillator time offset change rate and the uplink compensation preset period, determining the crystal oscillator time offset component in the downlink time offset measurement value corresponding to the target synchronization signal block.

7. The uplink synchronization method according to any one of claims 1 to 6, wherein, The way of performing uplink residual time offset compensation based on the crystal oscillator time offset component is: Based on the crystal oscillator time offset component, performing uplink residual time offset compensation on the crystal oscillator time offset component in the same direction as the time offset direction of the crystal oscillator time offset component.

8. The uplink synchronization method according to any one of claims 1 to 6, wherein, The way of performing uplink residual time offset compensation based on the Doppler residual time offset component is: Based on the Doppler residual time offset component, performing the uplink residual time offset compensation on the Doppler residual time offset component in the opposite direction of the time offset direction of the Doppler residual time offset component.

9. An uplink synchronization apparatus, characterized by comprising: Comprise: A downlink time offset measurement value acquisition module, configured to periodically receive a synchronization signal block and measure a downlink time offset measurement value corresponding to each synchronization signal block after completing initial downlink synchronization; A component extraction module, configured to extract a crystal oscillator time offset component and a Doppler residual time offset component from the downlink time offset measurement value corresponding to the target synchronization signal block; An uplink compensation module is configured to perform uplink residual time offset compensation based on the crystal oscillator time offset component and the Doppler residual time offset component before transmitting an uplink signal.

10. A ground terminal, characterized by The baseband processor comprises: The baseband processor is configured to periodically receive synchronization signal blocks and measure a downlink time offset measurement value corresponding to each synchronization signal block after completing initial downlink synchronization, extract a crystal oscillator time offset component and a Doppler residual time offset component from the downlink time offset measurement value corresponding to a target synchronization signal block, and perform uplink residual time offset compensation based on the crystal oscillator time offset component and the Doppler residual time offset component before transmitting an uplink signal.

11. An electronic device, comprising: The baseband processor comprises: The processor, the memory and the communication bus are configured to complete communication between each other; The memory stores program instructions executable by the processor, and the processor invokes the program instructions to execute the method according to any one of claims 1-8.

12. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer instructions, and the computer instructions make the computer execute the method according to any one of claims 1-8 when the computer runs the computer instructions.

13. A computer program product, characterised in that, The computer program product comprises a computer program, and the computer program is executed by the processor to implement the method according to any one of claims 1-8.

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