CN-122027430-A - Communication method for inhibiting peak-to-average ratio from being too high in orthogonal time-frequency space system

Abstract

The invention relates to the technical field of communication, in particular to a communication method for inhibiting the excessive peak-to-average ratio in an orthogonal time-frequency space system, which comprises the following steps of firstly converting a signal from a delay-Doppler domain which is convenient for channel characterization to a time-frequency domain which is convenient for modulation realization, secondly, adopting a T-SLM method to carry out preliminary inhibition on the peak-to-average ratio, generating a plurality of groups of candidate signals, selecting a group with the peak-to-average ratio lower than a preset threshold or minimum, thirdly, carrying out Hassenberg transformation on the selected signal to obtain a time domain signal, carrying out iterative limiting filtering treatment, adding a cyclic prefix, sending, fourthly, removing the cyclic prefix by a receiving end, recovering to the time-delay-Doppler domain through the Wiggner transformation and the octyl Fourier transformation, adopting a message transmission algorithm to carry out preliminary detection to obtain a hard decision value and a log likelihood ratio, and selecting a high reliability observation value based on the log likelihood ratio to construct a reliability selection matrix.

Inventors

• WANG KAIWEN

Assignees

• 王凯文

Dates

Publication Date

20260512

Application Date

20260403

Claims (8)

1. 1. A communication method for restraining peak-to-average ratio from being too high in an orthogonal time-frequency space system is characterized by comprising the following steps: step one, converting signals from delay-Doppler domain which is convenient for channel characterization to time-frequency domain which is convenient for modulation realization; Secondly, performing preliminary suppression on peak-to-average ratio by adopting a T-SLM method, generating a plurality of groups of candidate signals, and selecting a group with peak-to-average ratio lower than a preset threshold or the smallest; performing iterative limiting filtering processing on the selected signal to obtain a time domain signal, adding a cyclic prefix and then transmitting the time domain signal; Removing the cyclic prefix by the receiving end, recovering to a time delay-Doppler domain through the Wiggner transformation and the Fourier transformation, adopting a message transfer algorithm to perform preliminary detection to obtain a hard decision value and a log likelihood ratio, selecting a high-reliability observation value based on the log likelihood ratio, and constructing a reliability selection matrix; And fifthly, recovering the amplitude limiting noise from the high-reliability observed value by using compressed sensing and removing the amplitude limiting noise, and finally detecting the signal after removing the noise by adopting a message transmission algorithm again to recover the original bit sequence.
2. 2. The method according to claim 1, wherein the T-SLM method comprises generating Q groups of random phase sequences with the length M, multiplying the random phase sequences with the time-frequency domain signals, calculating peak-to-average ratios of the groups after Haisenberg conversion, comparing the peak-to-average ratios with a preset threshold, immediately selecting the smallest group if the current group is lower than the threshold, and otherwise selecting the smallest group.
3. 3. The method of claim 2, wherein the Q is 6 and the threshold is set to 9dB.
4. 4. The method of claim 1, wherein the iterative limiting filtering comprises setting a limiting rate gamma to calculate a threshold A, limiting the amplitude of the sampling points exceeding A, switching back to the delay-Doppler domain for frequency domain filtering, switching back to the time domain for completing one iteration, and repeating the iteration for 4 times.
5. 5. The method according to claim 1, wherein the message passing algorithm initially detects and sets the maximum iteration number to 20, approximates the interference and noise to gaussian variable updated mean and variance, converges to obtain a hard decision value, and calculates the log likelihood ratio.
6. 6. The method of claim 1, wherein selecting the high reliability observations in step four comprises defining the reliability of the observation nodes to be the minimum of the log likelihood ratios in their associated symbols, and selecting the first V most reliable nodes to construct a reliability selection matrix after ranking the reliability.
7. 7. The method of claim 1, wherein recovering clipping noise using compressed sensing includes subtracting the preliminary detection signal from the received signal to obtain a residual, filtering with a reliability selection matrix to obtain a compressed observation, and recovering sparse clipping noise using an orthogonal matching pursuit algorithm.
8. 8. The method of claim 1, wherein step five is performed by performing final detection again using a message passing algorithm, outputting hard decision symbols and demapping the recovered binary bit sequence.

Description

Communication method for inhibiting peak-to-average ratio from being too high in orthogonal time-frequency space system Technical Field The invention relates to the technical field of communication, in particular to a communication method for inhibiting the peak-to-average ratio from being too high in an orthogonal time-frequency-space system. Background Orthogonal time-frequency space (OTFS) is a novel multi-carrier modulation technique designed specifically for high-speed mobile communication scenarios. Compared with the traditional Orthogonal Frequency Division Multiplexing (OFDM) scheme, the OTFS directly maps information symbols to the time delay-Doppler domain for transmission, and the design can obviously inhibit inter-carrier interference caused by Doppler effect, so that more excellent error rate performance and communication reliability are shown in high-speed railway, internet of vehicles, unmanned aerial vehicle communication and other high-dynamic mobile environments. However, OTFS systems face a significant technical challenge in practical applications, namely the peak-to-average power of the signal is relatively high. Theoretical analysis and simulation results show that the upper limit of the peak-to-average ratio of the OTFS signal and the number N of Doppler grid points of the OTFS signal show an approximately linear growth relation. When N is larger to support higher Doppler resolution or more complex mobile environment, the peak power of the signal is obviously increased, a higher instantaneous power peak is easy to appear, and the peak-to-average ratio signal easily exceeds a linear working area when passing through a Power Amplifier (PA) at the front end of a radio frequency, so that nonlinear distortion is generated on the signal, and out-of-band spectrum expansion and in-band signal distortion are further caused, and the error code performance of the system is reduced. In addition, the higher peak-to-average ratio also puts more severe requirements on the dynamic range of devices such as a digital-to-analog converter (DAC) and an analog-to-digital converter (ADC), which not only increases the complexity of hardware design, but also increases the realization cost and energy consumption of the system, and becomes an important constraint factor of the OTFS technology towards actual deployment. The current method for reducing the peak-to-average ratio of the OTFS mainly comprises distortion class technologies such as mu-law companding and probability class technologies such as selective mapping (SLM) and Partial Transmission Sequence (PTS). Although the distortion technology is simple to realize and obvious in inhibiting effect, nonlinear processing can cause signal distortion to influence the error rate of the system. The probability type technology reduces the occurrence probability of a high peak value by carrying out linear transformation on signals, and the error rate performance is not affected, but the traditional SLM and PTS methods have the problem of high calculation complexity. In addition, the clipping and filtering method can introduce clipping noise while suppressing the peak-to-average ratio, and corresponding compensation processing is needed at the receiving end. Therefore, a communication method for restraining the peak-to-average ratio from being too high in an orthogonal time-frequency space system is provided. Disclosure of Invention The technical problem to be solved is that although the distortion technology is simple to realize and obvious in inhibiting effect, the nonlinear processing can cause signal distortion to influence the error rate of the system. The probability type technology reduces the occurrence probability of a high peak value by carrying out linear transformation on signals, and the error rate performance is not affected, but the traditional SLM and PTS methods have the problem of high calculation complexity. Aiming at the defects of the prior art, the invention provides an overload protection motor for a load-carrying machine, and further solves the technical problems in the background art. The invention aims at realizing the technical scheme that the communication method for restraining the peak-to-average ratio from being too high in an orthogonal time-frequency-space system comprises the following steps: step one, converting signals from delay-Doppler domain which is convenient for channel characterization to time-frequency domain which is convenient for modulation realization; Secondly, performing preliminary suppression on peak-to-average ratio by adopting a T-SLM method, generating a plurality of groups of candidate signals, and selecting a group with peak-to-average ratio lower than a preset threshold or the smallest; performing iterative limiting filtering processing on the selected signal to obtain a time domain signal, adding a cyclic prefix and then transmitting the time domain signal; Removing the cyclic prefix by the receiving end, re