Virtual subcarrier-based OTFS (Optical Transport File System) communication and inductance integrated PAPR suppression method

Abstract

The invention discloses a virtual subcarrier-based OTFS (Optical Transport File System) communication and inductance integrated PAPR (Peak to Average Power Ratio) suppression method. The method comprises the following steps of: searching a position of an optimal reserved virtual subcarrier; the OTFS communication and inductance integrated signal is converted into a time domain signal; calculating a signal threshold, if the amplitude of the time-domain signal is smaller than or equal to the signal threshold, outputting the time-domain signal, otherwise, reducing the amplitude of the time-domain signal; generating a shear noise signal by the time domain signal after the amplitude of the original signal is reduced; scaling the cut noise signal to obtain a scaling vector; updating the peak value reduction OTFS inductance integrated signal; and if the amplitude of the OTFS integrated signal with the reduced peak value is smaller than or equal to the signal threshold value or reaches the maximum number of iterations, terminating the algorithm and outputting to obtain the PAPR of the suppressed OTFS integrated signal, otherwise, continuing to reduce the amplitude of the time domain signal. According to the method, the OTFS and inductance integrated signal PAPR is rapidly suppressed, the convergence state is achieved, and the system stability is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated communication and sensing, and relates to an OTFS integrated communication and sensing PAPR suppression method based on virtual subcarriers. Background Art

[0002] With the increasing integration of radar and communication systems in terms of architecture and signal processing, integrated sensing and communication technologies are crucial for the development of the sixth-generation mobile network (6G). Since the modulation scheme based on Orthogonal Time Frequency Space (OTFS) was proposed by Hadani in 2017, OTFS has received extensive attention in integrated sensing and communication technologies due to its excellent performance in doubly selective channels. Moreover, the integrated communication and sensing signal waveform of OTFS has shown great promise in the ISAC field. As a new two-dimensional modulation technology. However, as a multi-carrier modulation technology, the integrated communication and sensing signal of OTFS inevitably has the problem of a relatively high Peak to Average Power Ratio (PAPR), which will lead to efficiency loss of high-power amplifiers and a significant reduction in power.

[0003] Rose Mary Augustine of the Department of Electrical Communication Engineering, Indian Institute of Science, first derived the upper bound of the PAPR of the integrated communication and sensing signal of OTFS and found that it increases linearly with the number of symbols To mitigate the PAPR problem, several techniques have been explored, which can be divided into three categories: predistortion techniques, coding techniques, and probabilistic techniques. Predistortion techniques usually reduce the amplitude of the signal, which will lead to a significant decrease in system performance. Chimala Naveen proposed the law compression technique, and proved that its ability to reduce the PAPR of the integrated communication and sensing signal of OTFS depends on the degree of signal distortion. Wang Zhenduo of Harbin Engineering University proposed a nonlinear correction active constellation expansion method, which uses parameter compression transformation to process the peak-reduced signal, achieving an observable PAPR reduction while maintaining good Bit Error Rate (BER) performance.

[0004] In addition, coding techniques usually optimize some codewords to minimize the PAPR of the signal. For example, Liu Mengxue of Zhejiang University proposed an autoencoder architecture using deep learning technology, while Wang Zhenduo of Harbin Engineering University introduced a precoded OTFS integrated communication and sensing signal system based on integral weighted fractional Fourier transform. Both achieved a trade-off between PAPR and BER performance at the cost of high computational complexity at the receiver. In contrast, the above techniques introduce additional distortion and noise to the integrated signal, resulting in a lack of adaptability and flexibility in practical applications. Summary of the Invention

[0005] The present invention aims to solve the technical problem that the integrated signal distortion affects the system stability. The present invention provides an OTFS communication-sensing integrated PAPR suppression method based on virtual subcarriers. The technical solution adopted is as follows: The OTFS communication-sensing integrated PAPR suppression method based on virtual subcarriers includes the steps of: S1. Search for the position of the optimal reserved virtual subcarrier; S2. Generate an OTFS communication-sensing integrated signal at the position of the virtual subcarrier outside the position of the optimal reserved virtual subcarrier, transform the OTFS communication-sensing integrated signal from the time-delay Doppler domain to the virtual subcarrier domain, and convert it into a time-domain signal; S3. Calculate the signal threshold according to the average amplitude of the time-domain signal. If the amplitude of the time-domain signal is less than or equal to the signal threshold, output the time-domain signal; otherwise, record the amplitude of the time-domain signal exceeding the signal threshold and proceed to the next step; S4. Reduce the amplitude of the time-domain signal exceeding the signal threshold, and generate a clipping noise signal by subtracting the time-domain signal with the reduced amplitude from the original signal; S5. Scale the clipping noise signal to obtain a scaling vector; S6. Update the peak-reduced OTFS communication-sensing integrated signal according to the clipping noise signal and the scaling vector; S7. If the amplitude of the peak-reduced OTFS communication-sensing integrated signal is less than or equal to the signal threshold or reaches the maximum number of iterations, terminate the algorithm and output the peak-reduced OTFS communication-sensing integrated signal to obtain the PAPR of the suppressed OTFS communication-sensing integrated signal; otherwise, go to step S3.

[0006] Advantages of the present invention: The PAPR suppression method of the OTFS communication-sensing integrated signal of the present invention can accurately reduce the signal at the peak, thereby quickly suppressing the PAPR of the communication-sensing integrated signal based on OTFS modulation, and can quickly achieve the convergence effect without multiple iterations; moreover, since the OTFS communication-sensing integrated signal can adapt to a high-dynamic environment, and the position where the peak-clipping signal is formed in the present invention is at the reserved virtual subcarrier, the data subcarriers are not changed, so the signal will not be distorted and the communication error rate of the signal is not affected, so it is relatively stable. Description of the Drawings

[0007] Figure 1 is a flowchart of the OTFS communication-sensing integrated PAPR suppression method based on virtual subcarriers provided by an embodiment of the present invention; Figure 2It is the CCDF curve diagram of the VTR algorithm provided by the embodiment of the present invention to suppress the PAPR of the OTFS communication-sensing integrated signal; Figure 3 It is the comparison diagram of the CCDF curves of different algorithms provided by the embodiment of the present invention to suppress the PAPR of the OTFS communication-sensing integrated signal; Figure 4 It is the comparison diagram of the communication bit error rate results of the OTFS communication-sensing integrated signal under different algorithms provided by the embodiment of the present invention. Specific Embodiments

[0008] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0009] Inspired by the Tone Reservation (TR) method, the present invention proposes a Peak to Average Power Ratio (PAPR) suppression algorithm for an Orthogonal Time Frequency Space (OTFS) system, called the Virtual Tone Reservation (VTR) method. The present invention adopts the virtual tone reservation method to suppress the PAPR of the OTFS communication-sensing integrated signal, and achieves an efficient PAPR suppression effect without signal distortion.

[0010] Referring to the attached Figure 1 drawings, the OTFS communication-sensing integrated PAPR suppression method based on virtual subcarriers of the present invention includes the following steps: S1. Search for the position of the optimal reserved virtual subcarrier; S2. Generate an OTFS communication-sensing integrated signal at the position of the virtual subcarrier outside the position of the optimal reserved virtual subcarrier, transform the OTFS communication-sensing integrated signal from the time-delay-Doppler domain to the virtual subcarrier domain, and convert it into a time-domain signal; S3. Calculate the signal threshold according to the average amplitude of the time-domain signal. If the amplitude of the time-domain signal is less than or equal to the signal threshold, output the time-domain signal; otherwise, record the amplitude of the time-domain signal exceeding the signal threshold and proceed to the next step; S4. Reduce the amplitude of the time-domain signal exceeding the signal threshold, and generate a clipping noise signal by subtracting the time-domain signal with reduced amplitude from the original signal; S5. Scale the clipping noise signal to obtain a scaling vector; S6. Update the peak-reduced OTFS communication-sensing integrated signal according to the clipping noise signal and the scaling vector; S7. If the amplitude of the peak-reduced OTFS integrated sensing and communication signal is less than or equal to the signal threshold or reaches the maximum number of iterations, terminate the algorithm and output the peak-reduced OTFS integrated sensing and communication signal to obtain the PAPR of the suppressed OTFS integrated sensing and communication signal. Otherwise, go to step S3.

[0011] The present invention first converts the time-delay - Doppler (DD) domain grid into virtual data subcarriers and virtual reserved subcarriers, and converts the two-dimensional data grid into a one-dimensional data grid. Among them, the virtual data subcarriers are used to carry radar and communication data, and the virtual reserved subcarriers are used to carry the generated peak-clipping signals. Then, the Firefly Algorithm (FA) is used to select the optimal positions of the reserved virtual subcarriers. After that, the generated peak-reduced OTFS integrated sensing and communication signal is updated through the Signal-to-Clipping Noise Ratio (SCR) algorithm, achieving the effect of quickly suppressing the PAPR of the OTFS-based integrated sensing and communication signal, and efficiently reducing the PAPR of the integrated sensing and communication signal without distorting the integrated signal.

[0012] Step S1 of the present invention includes: The position of the optimal reserved virtual subcarrier is expressed as: (1); In formula (1), is the position of the optimal reserved virtual subcarrier, represents the number of subcarriers, represents the number of symbols, represents the virtual subcarrier, and the OTFS integrated sensing and communication is dimension. After being converted into reserved virtual subcarriers, it becomes dimension, represents the transpose, represents the first virtual subcarrier, represents the th virtual subcarrier; is the secondary peak of the optimal reserved virtual subcarrier, and the secondary peak is used to evaluate the performance of the selected optimal reserved virtual subcarrier.

[0013] The optimization of the reserved virtual subcarriers is an NP-hard problem. In an embodiment of the present invention, the Firefly Algorithm (FA) is used to search for the positions of the optimal reserved virtual subcarriers.

[0014] FA is a nature-inspired metaheuristic algorithm applicable to solving heuristic search problems. Based on the flashing characteristics and mutual attraction of fireflies, FA is constrained by two rules: First, all fireflies are attracted to other fireflies regardless of their gender. Second, the mutual attraction is proportional to the brightness, and both will decrease as the distance between fireflies increases. Moreover, the brightness of a firefly represents the fitness value landscape.

[0015] Define each virtual frequency-domain kernel as a firefly, and randomly generate fireflies with the number of reserved virtual subcarriers as the constraint. The brightness of the firefly is determined by the secondary peak of the time-domain kernel.

[0016] The attraction between any two fireflies is expressed as: (2); In formula (2), is the attraction between any two fireflies, is the maximum attraction, is the brightness attenuation coefficient, is the Euclidean distance between fireflies, is the exponent.

[0017] If the brightness of the th firefly is greater than the brightness of the th firefly, then the th firefly will be attracted to the vicinity of the th firefly. Therefore, the position of the th firefly will be changed, expressed as: (3); In formula (3), is the step size, is a random vector following a uniform distribution on the interval (4), represents the position of the th firefly, represents the position of the th firefly.

[0018] Update the brightness of the fireflies, sort the brightness of the updated fireflies again, and repeat the operation until the self-set maximum number of iterations is reached, and output the current global best reserved virtual subcarriers.

[0019] In an embodiment of the present invention, step S2 includes: For the OTFS integrated communication and sensing signal, the information symbols in the time-delay - Doppler domain are converted into time-domain signals through the inverse symplectic Fourier transform and the Heisenberg transform. The time-domain signal of the OTFS integrated communication and sensing signal is expressed as: (4); In formula (4), denotes conjugate transpose operation, is the identity matrix, denotes Kronecker product, , denotes column-by-column vectorization, represents the information symbol in the time-delay Doppler domain, ISFFT represents inverse symplectic Fourier transform, and HT represents Heisenberg transform, represents the time-domain signal, , represents a matrix of dimension is the identity diagonal matrix, represents the N-point IDFT matrix, represents the N-point discrete Fourier transform matrix, represents the N-point inverse discrete Fourier transform matrix, is the number of subcarriers, is the number of symbols, represents the communication data of OTFS integrated sensing and communication in the time-delay Doppler domain.

[0020] Let the intermediate vector , then formula (4) is expressed as: (5); The OTFS integrated sensing and communication signal whose PAPR needs to be reduced is obtained.

[0021] First, there are several combinations when establishing blank virtual subcarriers. At this time, set 1 for the positions to be reserved and 0 for the data part. After searching, find a combination with the most concentrated peaks as the position of the reserved virtual subcarriers. Then generate radar and communication data, with the data at the reserved positions being 0. In order to carry the peak clipping signal generated later, the non-reserved positions carry radar and communication data. In this way, an OTFS integrated sensing and communication signal with a length of is formed.

[0022] The optimal position of the reserved virtual subcarriers is that this position is 0, which is used to carry the peak clipping signal generated later. The positions of the virtual subcarriers other than the reserved ones are used to carry radar and communication data. This is equivalent to adding two signals to form an OTFS integrated sensing and communication signal with low PAPR.

[0023] Compared with Orthogonal Frequency Division Multiplexing (OFDM), it is worth noting that the OTFS modulation in formula (5) is very similar to OFDM modulation, where can be regarded as having parallel data streams of virtual subcarriers in the virtual frequency domain, and a specific transformation matrix can be used to convert it into an OTFS integrated communication and sensing signal that requires PAPR reduction . From this perspective, methods for reducing PAPR widely used in OFDM systems, such as the TR method, can achieve the expected PAPR performance without signal distortion and can be used to suppress the PAPR of the OTFS integrated communication and sensing signal, that is, a new PAPR reduction method is proposed - the OTFS integrated communication and sensing PAPR suppression method based on virtual subcarriers.

[0024] In one embodiment of the present invention, step S3 includes: The signal threshold is expressed as: (6); In formula (6), is the signal threshold, is the self-set clipping ratio, is the average amplitude of the time-domain signal, represents the th iteration time-domain signal amplitude, represents the th iteration time-domain signal magnitude, represents the number of subcarriers, represents the number of symbols.

[0025] After obtaining the signal threshold, compare the amplitude of the time-domain signal at this time with the signal threshold. If the amplitude of the time-domain signal is less than or equal to the signal threshold, go to step S7 and directly output the time-domain signal. Otherwise, record the position where the magnitude of the time-domain signal is greater than the signal threshold, and then proceed to step S4.

[0026] In one embodiment of the present invention, step S4 includes: The clipped noise signal is expressed as: (7); In formula (7), represents the th iteration clipped noise signal, represents the signal threshold, represents the th iteration acquired time-domain signal phase, Denote the imaginary part; Combine the positions where the amplitude of the time-domain signal is greater than the signal threshold, and perform operations on the signals at these positions to generate a clipped signal, reduce the amplitude of the time-domain signal, and keep the phase of the time-domain signal unchanged. Do not process the positions where the amplitude of the time-domain signal is less than or equal to the signal threshold, that is, generate a clipping noise signal.

[0027] In one embodiment of the present invention, step S5 includes: The scaling vector is expressed as: (8); In formula (8), denotes the scaling value at the position in the scaling vector, so as to more quickly suppress the PAPR of the integrated communication and sensing signal, denotes the peak in the signal at the th iteration, is the scaling factor obtained by solving using the least squares method; The scaling factor is expressed as: (9); In formula (9), is the set of positions of each peak, denotes the clipped signal generated at the th iteration, is the clipping noise signal at the th iteration.

[0028] In one embodiment of the present invention, step S6 includes: The peak-reduced OTFS integrated communication and sensing signal is expressed as: (10); In formula (10), denotes the peak-reduced OTFS integrated communication and sensing signal at the th iteration, denotes the scaling vector, denotes the signal threshold, denotes the phase of the time-domain signal obtained at the th iteration, , denotes the number of subcarriers, denotes the number of symbols, denotes the imaginary part, denotes the peak in the signal at the th iteration, P represents the virtual subcarrier, denotes the th iteration of the time-domain signal.

[0029] In one embodiment of the present invention, step S7 includes: Determine the relationship between the amplitude of the peak-reduced OTFS integrated sensing and communication signal and the signal threshold. If the amplitude of the peak-reduced OTFS integrated sensing and communication signal is less than or equal to the signal threshold or the number of iterations reaches the maximum number of iterations set by itself, terminate the algorithm and output the peak-reduced OTFS integrated sensing and communication signal, and obtain the PAPR of the suppressed OTFS integrated sensing and communication signal. Otherwise, return to step S3 and continue to reduce the amplitude of the peak-reduced OTFS integrated sensing and communication signal.

[0030] The PAPR of the OTFS integrated sensing and communication signal is expressed as: (11); In formula (11), represents the average power of the signal, represents taking the average, represents the discrete OTFS integrated sensing and communication signal, represents the number of subcarriers, represents the number of symbols, represents the PAPR of the OTFS integrated sensing and communication signal.

[0031] The PAPR of the OTFS integrated sensing and communication signal is measured using the complementary cumulative distribution function, which represents the probability that the PAPR exceeds a predetermined peak power threshold, and is expressed as; (12); In formula (12), CCDF represents the complementary cumulative distribution function, is the predetermined peak power threshold, represents the probability of.

[0032] Similar to the TR technology, in formula (5), the virtual subcarriers can also be divided into data virtual subcarriers and reserved virtual subcarriers. The data virtual subcarriers are used to carry radar and communication data, while the reserved virtual subcarriers are used to generate the peak clipping signal. The present invention first searches for the positions of the reserved virtual subcarriers. Then, the scaling-SCR algorithm is used to generate a peak clipping signal that effectively reduces the PAPR.

[0033] The peak-reduced OTFS integrated sensing and communication signal is composed of a time-domain signal and a peak clipping signal, and is expressed as: (13); In formula (13), represents the OTFS integrated sensing and communication signal after reducing the PAPR, represents the OTFS integrated sensing and communication signal that needs to reduce the PAPR, Indicates the peak - clipped signal in the time domain, Is a symbol vector reserved for the virtual frequency domain, ; Since the virtual data sub - carriers and virtual reserved sub - carriers do not intersect, the reserved symbol vector Satisfies: (14); In formula (14), , And Are respectively the positions of the virtual sub - carriers outside the positions of the optimal reserved virtual sub - carriers and the set of positions of the optimal reserved virtual sub - carriers, Represents the virtual data sub - carriers, The virtual reserved sub - carriers are used to carry the generated peak - clipped signal; After applying the virtual sub - carrier reservation method, the PAPR of the peak - reduced OTFS integrated communication and sensing signal is obtained, which is expressed as: (15); In formula (15), Represents the average power of the signal, Represents the discrete OTFS integrated communication and sensing signal, Represents the peak - clipped signal; The peak - reduced OTFS integrated communication and sensing signal Is iteratively updated using the gradient algorithm, which is expressed as: (16); In formula (16), Represents a one - dimensional scaling vector, , represents the signal threshold, Is the clipping ratio, Is the time - domain kernel, Is the In the The sequence of Is circularly shifted to the peak position Is the virtual frequency - domain kernel, satisfying .

[0034] In summary, in order to implement the OTFS integrated communication and sensing PAPR suppression method based on virtual sub - carriers, it mainly includes two algorithms. The position of the optimal reserved virtual sub - carriers is searched by the firefly algorithm, and the VTR based on the gradient algorithm is used for PAPR reduction. The present invention will not cause signal distortion and thus will not affect its communication bit - error rate, thereby improving the stability of the integrated system. Moreover, the present invention can quickly suppress the PAPR of the integrated communication and sensing signal based on OTFS modulation and make it quickly reach the convergence state.

[0035] The effects of the present invention are further illustrated through simulation below.

[0036] 1. Simulation conditions: The simulation of the present invention is carried out in the software environment of MATLAB R2022a.

[0037] 2. Simulation content: In the experimental simulation, the number of subcarriers is set to 128, and the number of symbols is 64, so the total number of virtual tones is 8192. The number of the virtual reserved subcarrier set (peak reduction tone, PRTs) is set to 320, because it usually needs to account for 3% - 5% of the total tones. The modulation method uses Quadrature Phase Shift Keying (QPSK), and the remaining simulation parameters are shown in Table 1.

[0038] Table 1 Simulation parameter table

[0039] 3. Analysis of simulation effects: The simulation results are referred to Appendix Figure 2 , and from Appendix Figure 2 it can be seen that when , the PAPR of the original signal (Original) is 12.75 dB. After 1 iteration, the PAPR is 3.9 dB, suppressing 8.85 dB; after 2 iterations, the PAPR is 3.2 dB, suppressing 9.55 dB; after 3 iterations, the PAPR is 3.02 dB, suppressing 9.73 dB; after 4 iterations, the PAPR is 3.0 dB, suppressing 9.75 dB, and a good suppression effect can be achieved.

[0040] It can be seen from the simulation result graph that many peaks can be eliminated in the first iteration, and then gradually decrease. The third and fourth iterations basically tend to converge, and a good PAPR suppression effect can be achieved.

[0041] Appendix Figure 3 shows the PAPR reduction performance under different methods. The PAPR reduction values of the original signal (Original), VTR method, law compression method, CF method, and PTS method are 8.8, 8.2, 7.4, and 6.6 dB respectively. The results show that all methods can significantly reduce the PAPR, but the VTR method is better than other methods.

[0042] Appendix Figure 4 intuitively shows the original signal (Original), The law compression method, partial transmit sequence (PTS), and clipping factor (CF) method reduce the bit error rate performance of the OTFS system. This is because these three methods will cause signal distortion, thereby reducing the bit error rate performance. In contrast, the bit error ratio (BER) of the VTR method of the present invention is consistent with the original signal. The results show that the VTR method of the present invention achieves a reduction in PAPR without introducing signal distortion. Therefore, the VTR method proposed by the present invention is superior to the other three methods.

[0043] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement, and improvement made within the technical scope disclosed by the present invention and within the spirit and principle of the present invention by those skilled in the art should be covered by the protection scope of the present invention.

Claims

1. OTFS integrated communication and sensing PAPR suppression method based on virtual subcarriers, characterized in that Including the steps: S1. Search for the position of the optimal reserved virtual subcarrier; S2. Generate an OTFS integrated sensing and communication signal at the positions of virtual subcarriers outside the position of the optimal reserved virtual subcarrier, transform the OTFS integrated sensing and communication signal from the time-delay - Doppler domain to the virtual subcarrier domain, and convert it from the virtual subcarrier domain to a time-domain signal; S3. Calculate a signal threshold based on the average amplitude of the time-domain signal. If the amplitude of the time-domain signal is less than or equal to the signal threshold, output the time-domain signal; otherwise, record the amplitude of the time-domain signal exceeding the signal threshold and proceed to the next step; S4. Reduce the amplitude of the time-domain signal exceeding the signal threshold, and subtract the time-domain signal with the reduced amplitude from the original signal to generate a clipping noise signal; S5. Scale the clipping noise signal to obtain a scaling vector; S6. Update the peak-reduced OTFS integrated sensing and communication signal according to the clipping noise signal and the scaling vector; S7. If the amplitude of the peak-reduced OTFS integrated sensing and communication signal is less than or equal to the signal threshold or the maximum number of iterations is reached, terminate the algorithm and output the peak-reduced OTFS integrated sensing and communication signal to obtain the PAPR of the suppressed OTFS integrated sensing and communication signal; otherwise, go to step S3.

2. The OTFS integrated communication and sensing PAPR suppression method based on virtual subcarriers according to claim 1, wherein, The step S1 includes: The position of the optimal reserved virtual subcarrier is represented as: (1)； In formula (1), is the position of the optimal reserved virtual subcarrier, represents the number of subcarriers, represents the number of symbols, represents the virtual subcarrier. The OTFS integrated sensing and communication is dimensional. After being converted into the reserved virtual subcarrier, it becomes dimensional, represents the transpose, represents the first virtual subcarrier, represents the th virtual subcarrier; is the secondary peak of the optimal reserved virtual subcarrier, and the secondary peak is used to evaluate the performance of the selected optimal reserved virtual subcarrier.

3. The OTFS integrated communication and sensing PAPR suppression method based on virtual subcarriers according to claim 1, characterized in that, The step S2 includes: For the OTFS integrated sensing and communication signal, the information symbol in the time-delay - Doppler domain is transformed into a time-domain signal through the inverse symplectic Fourier transform and the Heisenberg transform. The time-domain signal of the OTFS integrated sensing and communication signal is represented as: (4)； In formula (4), represents the conjugate transpose operation, is the identity matrix, represents the Kronecker product, , represents column-by-column vectorization, represents the information symbol in the time-delay Doppler domain, ISFFT represents the inverse symplectic Fourier transform, and HT represents the Heisenberg transform, represents the time-domain signal, , represents a matrix of dimension is the unit diagonal matrix, represents the \(N\)-point IDFT matrix, represents the \(N\)-point discrete Fourier transform matrix, represents the \(N\)-point inverse discrete Fourier transform matrix, is the number of subcarriers, is the number of symbols, represents the communication data of OTFS integrated sensing and communication in the time-delay Doppler domain; Let the intermediate vector , formula (4) is expressed as: (5)； Obtain the OTFS integrated sensing and communication signal whose PAPR needs to be reduced.

4. A method for PAPR suppression of integrated communication and sensing based on virtual subcarriers in OTFS according to claim 1, characterized in that, The step S3 includes: The signal threshold is represented as: (6)； In formula (6), is the signal threshold,[[]] is the self-set clipping ratio,[[]] is the average amplitude of the time-domain signal,[[]] represents the th iteration of the amplitude of the time-domain signal,[[]] represents the th iteration of the magnitude of the time-domain signal,[[]] represents the number of subcarriers,[[]] represents the number of symbols; After obtaining the signal threshold, compare the amplitude of the current time-domain signal with the signal threshold. If the amplitude of the time-domain signal is less than or equal to the signal threshold, enter step S7 and directly output the time-domain signal; otherwise, record the position where the amplitude of the time-domain signal is greater than the signal threshold, and then proceed to step S4.

5. A method for suppressing PAPR in an integrated communication and sensing system based on virtual subcarriers for OTFS according to claim 1, characterized in that, The step S4 includes: The clipping noise signal is represented as: (7)； In formula (7), represents the clipped noise signal at the -th iteration, represents the signal threshold, represents the phase of the time-domain signal obtained at the -th iteration, represents the imaginary part; Combined with the positions where the amplitude of the time-domain signal is greater than the signal threshold, the signals at these positions are operated to generate a clipped signal, reducing the amplitude of the time-domain signal while keeping the phase of the time-domain signal unchanged. The positions where the amplitude of the time-domain signal is less than or equal to the signal threshold are not processed, that is, the clipping noise signal is generated.

6. The OTFS communication-sensing integrated PAPR suppression method based on virtual subcarriers according to claim 1, wherein, The step S5 includes: The scaling vector is represented as: (8)； In formula (8), represents the scaling value at the position in the scaling vector, so as to more quickly suppress the PAPR of the integrated communication and sensing signal, represents the peak value in the signal at the th iteration, is the scaling factor obtained when solving by the least squares method; The scaling factor is represented as: (9)； In formula (9), is the set of positions of each peak, represents the peak-clipping signal generated during the -th iteration, and is the clipping noise signal during the 7. A method for suppressing PAPR in an integrated communication and sensing system based on virtual subcarriers for OTFS according to claim 1, characterized in that, The step S6 includes: The peak-reduced OTFS integrated sensing and communication signal is represented as: (10)； In formula (10), represents the peak-reduced OTFS integrated communication and sensing signal at the -th iteration, represents the scaling vector, represents the signal threshold, represents the phase of the time-domain signal obtained at the -th iteration, , represents the number of subcarriers, represents the number of symbols, represents the imaginary part, represents the peak in the signal at the -th iteration, P represents the virtual subcarrier, represents the time-domain signal at the -th iteration.

8. An OTFS integrated communication and sensing PAPR suppression method based on virtual subcarriers according to claim 1, characterized in that The step S7 includes: Judge the relationship between the amplitude of the peak-reduced OTFS integrated sensing and communication signal and the signal threshold. If the amplitude of the peak-reduced OTFS integrated sensing and communication signal is less than or equal to the signal threshold or the number of iterations reaches the self-set maximum number of iterations, terminate the algorithm and output the peak-reduced OTFS integrated sensing and communication signal to obtain the PAPR of the suppressed OTFS integrated sensing and communication signal; otherwise, return to step S3 to continue reducing the amplitude of the peak-reduced OTFS integrated sensing and communication signal; The PAPR of the OTFS integrated sensing and communication signal is represented as: (11)； In formula (11), represents the average power of the signal, represents taking the average, represents the discrete OTFS integrated communication and sensing signal, represents the number of subcarriers, represents the number of symbols, represents the PAPR of the OTFS integrated communication and sensing signal.

9. A method for PAPR suppression of integrated communication and sensing based on virtual subcarriers in OTFS according to claim 8, characterized in that The PAPR of the OTFS integrated sensing and communication signal is measured using the complementary cumulative distribution function, representing the probability that the PAPR exceeds a predetermined peak power threshold, expressed as; (12)； In formula (12), CCDF represents the complementary cumulative distribution function, is a predetermined peak power threshold, represents the probability of.

10. A method for PAPR suppression of integrated communication and sensing based on virtual subcarriers in OTFS according to claim 9, characterized in that, The peak-reduced OTFS integrated sensing and communication signal is composed of a time-domain signal and a peak-clipping signal, expressed as: (13)； In formula (13), represents the OTFS integrated communication and sensing signal after PAPR reduction, represents the OTFS integrated communication and sensing signal whose PAPR needs to be reduced, represents the peak clipping signal in the time domain, is the virtual frequency domain reserved symbol vector, ; Since the virtual data subcarriers and the virtual reserved subcarriers do not intersect, the pilot symbol vector satisfies: (14)； In formula (14), , and are respectively the positions of virtual subcarriers outside the position of the optimal reserved virtual subcarrier and the set of positions of the optimal reserved virtual subcarriers, represents a virtual data subcarrier, a virtual reserved subcarrier for carrying the generated peak clipping signal; After applying the virtual subcarrier reservation method, the PAPR of the peak-reduced OTFS integrated sensing and communication signal is obtained, expressed as: (15)； In formula (15), represents the average power of the signal, represents the discrete OTFS integrated communication and sensing signal, represents the peak - clipped signal; Peak-reduced OTFS integrated communication and sensing signal Iteratively updated using the gradient algorithm, expressed as: (16)； In formula (16), represents a one-dimensional scaling vector, , represents the signal threshold, is the clipping ratio, is the time-domain kernel, is the th iteration to 's sequence is circularly shifted to the peak position , is the virtual frequency-domain kernel, satisfying .

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