CN-122027426-A - Time-frequency synchronization method, system, electronic equipment and storage medium

CN122027426ACN 122027426 ACN122027426 ACN 122027426ACN-122027426-A

Abstract

The invention discloses a time-frequency synchronization method, a time-frequency synchronization system, electronic equipment and a storage medium, and relates to the technical field of communication. The method comprises the steps of obtaining a received signal, carrying out iterative equivalent matched filtering on the received signal based on symbol delay to obtain a burst signal preliminary positioning result, generating a local training symbol based on a preset frequency domain spread spectrum sequence, and carrying out parallel matched filtering by using the local training symbol and the burst signal preliminary positioning result to obtain a combined detection result of frequency offset estimation and time domain synchronization. The invention greatly improves the carrier synchronization performance of the OFDM satellite communication system through innovative iterative equivalent matching detection, frequency domain sequence design and parallel matching processing, has quicker synchronization, more accurate frequency offset estimation, larger coverage frequency offset and stronger weak signal adaptability, reduces the realization complexity and resource cost, and has remarkable engineering application value.

Inventors

XIANG ZUOWEI
DENG SHIYAN
ZHANG YU
TAN SONGGAO
WANG MINGQING

Assignees

中国星网网络应用有限公司

Dates

Publication Date: 20260512
Application Date: 20260211

Claims (14)

1. A method for time-frequency synchronization, comprising: Obtaining a received signal, and performing iterative equivalent matched filtering on the received signal based on symbol delay to obtain a burst signal preliminary positioning result; and generating a local training symbol based on a preset frequency domain spread spectrum sequence, and performing parallel matched filtering by using the local training symbol and the initial positioning result of the burst signal to obtain a joint synchronous detection result.
2. A time-frequency synchronization method according to claim 1, wherein the iterative equivalent matched filtering of the received signal based on the symbol delays comprises, And performing equivalent matched filtering on the received signal on a time axis by sliding with a preset step length by using the double time windows to obtain a burst signal preliminary positioning result.
3. A time-frequency synchronization method according to claim 1 or 2, characterized in that the symbol delay is a delay of two time windows equal to an integer multiple of the complete symbol period in the received signal.
4. A time-frequency synchronization method according to claim 3, wherein the preset step length comprises a first step length and a second step length, the first step length is used for performing coarse search in a time domain to quickly locate a time section in which a matching peak may exist, and the second step length is used for performing fine search in a neighborhood to accurately determine the starting position of the burst signal after the peak is detected.
5. The method of claim 4, wherein the first step size does not exceed a burst pilot repetition structure length and the second step size is a single symbol length, or wherein the first step size does not exceed a burst pilot repetition structure length and the second step size is a progressive shortening within a range of not more than a single symbol length.
6. A time-frequency synchronization method according to claim 4 or 5, wherein generating local training symbols based on a preset frequency domain spreading sequence comprises, And performing cyclic shift on the frequency domain spread spectrum sequence in the frequency domain according to different assumed subcarrier offsets, obtaining a plurality of groups of offset reference sequences after fast Fourier transform, and converting each group of offset reference sequences into a local training symbol corresponding to the time domain.
7. The method of claim 6, wherein the same reference symbols as the frequency domain spreading code of the transmitting end are used as the frequency domain spreading sequence.
8. The method of claim 1, wherein the parallel matched filtering is performed using the local training symbols and the initial positioning result of the burst signal to obtain the joint synchronization detection result, comprising, The local training symbols are parallelly related with the initial positioning result of the burst signal, and a related value sequence under the corresponding bias assumption is obtained; and determining the integer multiple carrier frequency offset estimation matched with the received signal according to the global maximum correlation peak.
9. The method of claim 8 wherein the integer multiple carrier frequency offset estimate is determined by a subcarrier offset and a subcarrier spacing frequency corresponding to a global maximum correlation peak.
10. The method of claim 9, wherein the fractional frequency offset estimate is determined based on an integer multiple of the carrier frequency offset estimate and a phase change of a global maximum correlation peak.
11. The method of claim 10 wherein the starting position of the synchronization training symbol is the time window position of the global maximum correlation peak.
12. A time-frequency synchronization system, characterized in that the system comprises, The burst signal positioning module is used for acquiring a received signal, and performing iterative equivalent matched filtering on the received signal based on symbol delay to acquire a burst signal primary positioning result; And the joint synchronization module is used for generating a local training symbol based on a preset frequency domain spread spectrum sequence, and carrying out parallel matched filtering by using the local training symbol and the initial positioning result of the burst signal to obtain a joint synchronization detection result.
13. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method of any one of claims 1 to 11 when executing the computer program.
14. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the method of any one of claims 1 to 11.

Description

Time-frequency synchronization method, system, electronic equipment and storage medium Technical Field The present invention relates to the field of communications technologies, and in particular, to a time-frequency synchronization method, a system, an electronic device, and a storage medium for a low-orbit satellite burst wideband OFDM system. Background In the current OFDM communication scenario, for the case of no prior information, the receiver typically uses sliding window energy to implement OFDM frame detection. Although the method improves the frame detection performance to a certain extent, the method has the limitation that the power of a received signal is easy to be confused with the noise power when the signal-to-noise ratio is low, so that the robustness is poor in an interference communication scene, and the accuracy and the speed of the frame detection are required to be improved. For burst OFDM signals with larger duty ratio, because the time domain duration is short, the frequency spectrum is widened, the energy distribution is complex, and common methods such as point-by-point sliding correlation matching, time-frequency joint detection and the like need to carry out intensive operation in the whole sampling window, a large amount of correlation calculation and accumulation operation are needed, and the processor resource consumption is too high, the detection delay is obvious, the instantaneity is difficult to ensure, and the overall detection efficiency is low. In addition, the existing OFDM communication carrier synchronization method generally estimates a Fractional Frequency Offset (FFO) based on a maximum likelihood estimation ML algorithm of a cyclic prefix, and then estimates an Integer Frequency Offset (IFO) by using a subcarrier offset in a frequency domain. Or time-frequency synchronization is accomplished with specially constructed pilot symbols. Although the existing method can complete synchronization, the method still has the defects of low burst signal detection efficiency, low accuracy, limited time-frequency estimation precision, limited noise immunity and the like. Disclosure of Invention The invention aims to overcome the defects in the prior art and provides a time-frequency synchronization method, a system, electronic equipment and a storage medium based on burst signal detection. The invention solves the technical problems by the following technical scheme: in a first aspect, a time-frequency synchronization method is provided, including: Obtaining a received signal, and performing iterative equivalent matched filtering on the received signal based on symbol delay to obtain a burst signal preliminary positioning result; and generating a local training symbol based on a preset frequency domain spread spectrum sequence, and performing parallel matched filtering by using the local training symbol and the initial positioning result of the burst signal to obtain a joint synchronous detection result. In a second aspect, a time-frequency synchronization system is provided, comprising, The burst signal positioning module is used for acquiring a received signal, and performing iterative equivalent matched filtering on the received signal based on symbol delay to acquire a burst signal primary positioning result; And the joint synchronization module is used for generating a local training symbol based on a preset frequency domain spread spectrum sequence, and carrying out parallel matched filtering by using the local training symbol and the initial positioning result of the burst signal to obtain a joint synchronization detection result. In a third aspect, there is provided an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the method of any of the preceding claims when executing the computer program. In a fourth aspect, a computer readable storage medium is provided, on which a computer program is stored which, when executed by a processor, implements the method of any of the preceding claims. The invention has the beneficial effects that: The invention greatly improves the carrier synchronization performance of the OFDM satellite communication system through innovative burst signal detection, iterative equivalent matching detection, frequency domain sequence design and parallel matching processing, and has the advantages of quicker synchronization, more accurate frequency offset estimation, larger coverage frequency offset, stronger weak signal adaptability, reduced realization complexity and resource overhead and obvious engineering application value. Drawings Fig. 1 is a flowchart of a time-frequency synchronization method according to an exemplary embodiment of the present invention. Fig. 2 is a schematic diagram of the result of iterative equivalent matched filtering according to an exemplary embodiment of the present invention. Fig. 3 is a schematic diagram of th