Improved partial transmission sequence method (PTS) technology in universal filtered multicarrier (UFMC) system

Abstract

The invention provides an improved partial transmission sequence (PTS) technology capable of simultaneously improving the safety performance and the peak-to-average power ratio performance of a universal filtered multi-carrier (UFMC) system, and aims to enhance the signal safety and improve the transmission performance of the system while the algorithm complexity is not increased. According to the invention, a partial sequence transmission method is introduced, and a PTS method and a UFMC system both have the step of partitioning subcarriers, so that the PTS method and the UFMC system can be effectively combined, and the peak-to-average power ratio is reduced without increasing the system complexity. The chaotic system provides a chaotic sequence, the chaotic sequence is introduced into subband cyclic shift of the PTS, and signal encryption operation is realized while the peak-to-average power ratio of the system is reduced.

Description

Technical Field

[0001] This invention belongs to the fields of optical transmission technology and encryption technology in the field of communication technology, and in particular relates to an improved Partial Transmission Sequence (PTS) technique in Universal Filtered Multicarrier (UFMC) systems. Background Technology

[0002] With the rapid development of communication technology, 5G networks have been commercially deployed on a large scale. New types of communication services are constantly emerging, such as cloud computing, big data, artificial intelligence, and the industrial internet. These high-tech advancements are driving an explosive growth in information transmission volume, making the stable performance of information transmission based on Passive Optical Networks (PON) crucial. At the same time, cybersecurity threats are spreading rapidly, and various cyberattacks have seriously infringed upon the rights and interests of enterprises and even nations, causing significant economic losses. In the future era of the Internet of Things (IoT), cybersecurity will even affect the lives and property safety of every citizen. Therefore, cybersecurity requires continuous exploration and improvement.

[0003] Based on the goal of improving the transmission performance of passive optical networks (PONs), this invention employs Universal Filter Multicarrier (UFMC) modulation. Compared to OFDM, UFMC modulation offers advantages such as lower out-of-band leakage, higher spectral efficiency (lower synchronization requirements eliminate the need for a CP, reducing overhead and increasing spectral efficiency), and insensitivity to frequency and phase offset. Furthermore, compared to FBMC systems, UFMC combines multiple antenna technologies and simplifies filter length. Based on the above analysis of the three multicarrier technologies, UFMC balances the advantages and disadvantages of the other two multicarrier modulation methods and integrates well with existing hardware. UFMC technology is considered a key technology for multi-user access in next-generation PONs. With the continuous increase in fiber optic communication transmission capacity, the number of users, and computing power, the security of optical signal transmission faces severe challenges.

[0004] Multicarrier modulation (MCM) has many advantages but a common drawback: peak-to-average power ratio (PAPR), which leads to nonlinear distortion at the optical receiver. Current research suggests two main categories of techniques for reducing PAPR: distortion-based and distortion-free techniques. Since distortion-based techniques degrade signal transmission performance, this invention focuses on distortion-free techniques, which primarily include three categories: distortion-based techniques, coding techniques, and probabilistic scrambling techniques. Comparative studies have shown that probabilistic techniques do not cause signal distortion, nor do they introduce additional in-band noise or out-of-band radiation. Furthermore, their performance is unaffected by the coding method or the number of subcarriers. Based on these advantages, this invention focuses on further research within probabilistic techniques, including Selected Mapping (SLM) and Partial Transmit Sequence (PTS). Both SLM and UFMC systems require subcarrier grouping followed by IFFT operations. Therefore, introducing PTS into UFMC systems can reduce both the system's PAPR and the algorithm's complexity.

[0005] Meanwhile, PTS technology can effectively reduce the PAPR value of the signal without affecting the BER performance of the system. For the high PAPR problem of signals in high-speed UFMC transmission systems, this paper proposes to prioritize PTS technology as the main method for signal PAPR suppression.

[0006] Although the PTS method is not limited by the number of carriers and can effectively and without distortion reduce the peak-to-average power ratio of multi-carrier signals, the PTS method requires the transmission of phase factors as sideband information, which will bring about signal redundancy problems. Therefore, this invention innovatively combines it with signal chaotic encryption. Summary of the Invention

[0007] This invention aims to propose an improved Partial Transmission Sequence (PTS) technique in Universal Filtered Multicarrier (UFMC) systems to solve the information redundancy problem of PTS while improving signal transmission performance and security performance.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] This invention provides an improved Partial Transmission Sequence (PTS) technique in Universal Filtered Multicarrier (UFMC) systems, comprising the following steps:

[0010] S1, QAM modulation is performed on the acquired signal to be transmitted to obtain the modulated signal;

[0011] S2, perform subband allocation and serial-to-parallel conversion on the modulated signal to obtain PTS group data for each subband;

[0012] S3, perform N-point IFFT processing on the PTS grouped data of each sub-band and filter the filter of each sub-band to obtain the time-domain sub-block sequence;

[0013] S4, using a hyperchaotic model to generate a chaotic sequence, and processing the chaotic sequence to obtain the phase factor required by PTS;

[0014] S5, based on the time-domain sub-block sequence, the phase factor is multiplied by the corresponding sub-band, and the resulting sub-bands are filtered by their respective filters and then added together to calculate the peak-to-average power ratio (PAPR).

[0015] S6. Circularly shift the sub-bands and repeat step S5 above. After traversing all cases, compare all peak-to-average power ratio (PAPR) values ​​and select the sub-band arrangement corresponding to the smallest PAPR value for signal transmission.

[0016] Preferably, S2 includes the following sub-steps:

[0017] S2.1, Subband allocation includes allocating multiple subcarriers to a subband. A general UFMC system includes B subbands, each subband has M subcarriers, and the total number of subcarriers is N, i.e., N = B * M; each subband is allocated one filter.

[0018] S2.2, PTS grouping is performed on the frequency domain subband of the UFMC system to obtain PTS grouped data X = [X1, X2, X3, ..., X N PTS grouped data satisfies Where v = 1, 2, ..., B, and B is the number of sub-bands.

[0019] Preferably, S3 includes the following sub-steps:

[0020] S3.1, for the PTS packet data of B subbands, after sequentially performing N-point IFFT transformation according to the UFMC transceiver structure, S is obtained. j =[S j (0),S j (1),…,S j (N-1)] T j = (1, 2, ... B), S j After filtering, the temporal sub-block sequence is obtained.

[0021] x j =[x j (0),x j (1),…,x j (N+1-1)] T j = (1, 2, ... B);

[0022] S3.2, the filter adopts a Chebyshev filter h, the filter length is L, and x(n) is the baseband equivalent discrete-time signal within a symbol time interval, i.e.

[0023]

[0024] Among them, input data X i (m) is a frequency domain subcarrier signal, which is obtained by digitally modulating a bit stream of independent random variables with equal probability and uniform distribution. The mean of the real and imaginary parts of all constellation points is zero and the variance is equal; n is the discrete time index.

[0025] Preferably, in S3.1: PTS needs to divide the frequency domain sequence X of length N into V non-overlapping frequency domain sub-block sequences X according to the block division rules. V ;

[0026] Each of the segmented frequency domain sub-block sequences is multiplied by a complex phase factor b. v Add them together, and then perform an IFFT transformation to the time domain to obtain the final transmitted signal x, that is:

[0027]

[0028] Where, x v It is a time-domain signal sequence.

[0029] Preferably, in S3.2: the process of dividing the UFMC subcarriers in the frequency domain into subbands and the process of PTS dividing the frequency domain sequence into blocks are combined, that is, the block division steps of some transmission sequence methods are omitted, and the subbands divided by the UFMC subcarriers are used as the sub-block sequence of PTS. After IFFT operation and filtering, they are multiplied and added with the phase rotation factor, and then sent to the channel for transmission.

[0030] Preferably, in S4: the hyperchaotic model is a cellular neural network (CNN) hyperchaotic model, and the CNN hyperchaotic model is represented as:

[0031]

[0032] in,

[0033] Among them, j, a j x j S jk f(x) j The symbols ) represent the marker, threshold, constant, state variable, relationship parameters between variables, and cell output, respectively. and A jk All are 0.

[0034] Preferably, in S4, the hyperchaotic model generates a chaotic sequence X1, and the phase factor is generated from the chaotic sequence.

[0035] b v =binary2factor(floor(mod(X1,2)),1).

[0036] Preferably, in S5: when the phase factor is multiplied with the corresponding sub-band, the phase factor multiplied by the subcarriers in each sub-band is the same.

[0037] Preferably, in S6: during the cyclic shift, each sub-band moves one position as a whole each time, while the position of the phase factor remains unchanged.

[0038] Preferably, in S6: a vector is set to record the peak-to-average power ratio (PAPR) value obtained by multiplying and adding the phase factor after the subband is cyclically shifted.

[0039] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0040] To simultaneously improve the security and transmission performance of UFMC systems, this invention introduces a partial transmission sequence (PTS) method and a chaotic model for the signal. The PTS method is improved by reducing its complexity and redundancy while maintaining its peak-to-average power ratio (PAPR). The PTS method achieves PAPR reduction by optimizing the phase information of subcarriers and selecting the time-domain signal with the lowest PAPR for transmission. Its complexity reduction is achieved by directly using UFMC sub-bands as the smallest unit of PTS, omitting the block division step and greatly simplifying the algorithm.

[0041] Meanwhile, the improved PTS method of this invention overcomes the drawback of traditional methods that require the transmission of phase factors as sideband information. This is achieved by generating identical phase factors at the transmitting and receiving ends using a synchronized hyperchaotic system. While reducing the peak-to-average power ratio of the transmitted signal, the number of bits in the cyclic shift of the subbands is random, disrupting the transmission order of the subcarriers and achieving frequency domain encryption of the signal. Attached Figure Description

[0042] Figure 1 This is an overall flowchart of the improved Partial Transmission Sequence (PTS) technique in this embodiment of the invention;

[0043] Figure 2 This is a detailed schematic diagram of the sub-band cyclic shift in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of CCDF in an embodiment of the present invention, wherein the number of subcarriers is 1024, the number of subbands is 16, and each subband has 64 subcarriers. Detailed Implementation

[0045] This invention aims to propose an improved Partial Transmission Sequence (PTS) technique for Universal Filtered Multicarrier (UFMC) systems, addressing the information redundancy problem of PTS while simultaneously improving signal transmission and security performance. This invention introduces the PTS method because both PTS and UFMC systems involve subcarrier segmentation; therefore, the two can be effectively combined to reduce the peak-to-average power ratio (PAPR) without increasing system complexity. Furthermore, a chaotic sequence is provided using a chaotic model and introduced into the subband cyclic shift of the PTS, achieving signal encryption while reducing the PAPR.

[0046] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0047] Figure 1 This is an overall flowchart of the improved Partial Transmission Sequence (PTS) technique according to an embodiment of the present invention.

[0048] like Figure 1 As shown in this embodiment, an improved Partial Transmission Sequence (PTS) technique in a Universal Filtered Multicarrier (UFMC) system includes the following steps:

[0049] S1, QAM modulation is performed on the acquired signal to be transmitted to obtain the modulated signal.

[0050] In this embodiment, the modulation method used is 16-QAM modulation.

[0051] S2 performs subband allocation and serial-to-parallel conversion on the modulated signal to obtain PTS group data for each subband.

[0052] Specifically, step S2 includes the following sub-steps:

[0053] S2.1 Subband allocation includes allocating multiple subcarriers to a subband. A Universal Filtered Multicarrier (UFMC) system includes B subbands, each subband has M subcarriers, and the total number of subcarriers is N, i.e., N = B * M; each subband is allocated one filter.

[0054] In this embodiment, the entire bandwidth containing N subcarriers after 16-QAM modulation is divided into B subbands, so that each subband contains M subcarriers.

[0055] S2.2, To reduce the algorithmic complexity of the partial transmission sequence method, PTS groups are directly performed using the frequency domain subbands of the UFMC as units, resulting in PTS group data X = [X1, X2, X3, ..., X...]. N PTS groups satisfy Where v = 1, 2, ..., B, and B is the number of sub-bands.

[0056] S3, perform N-point IFFT processing on the PTS grouped data of each sub-band and filter the filter of each sub-band to obtain the time-domain sub-block sequence.

[0057] Specifically, step S3 includes the following sub-steps:

[0058] S3.1, after sequentially performing N-point IFFT transformation on the PTS packet data of B subbands according to the UFMC transceiver structure, we obtain S. j =[S j (0),S j (1),…,S j (N-1)] T j = (1, 2, ... B), S j After filtering, the temporal sub-block sequence x is obtained. j =[x j (0),x j (1),…,x j (N+1-1)] T ,j=(1,2,...B).

[0059] Furthermore, the Partial Transmission Sequence (PTS) method requires dividing a frequency domain sequence X of length N into V non-overlapping frequency domain sub-block sequences X according to a block division rule. V .

[0060] Each of the segmented frequency domain sub-block sequences is multiplied by a complex phase factor b. v Add them together, and then perform an IFFT transformation to the time domain to obtain the final transmitted signal x, that is:

[0061]

[0062] Where, x v It is a time-domain signal sequence.

[0063] S3.2, In this example, a Chebyshev filter h is used, with a filter length of L. x(n) is the baseband equivalent discrete-time signal within a symbol time interval, i.e.

[0064]

[0065] Among them, input data X i (m) is a frequency domain subcarrier signal, which is obtained by digitally modulating a bit stream of independent random variables with equal probability and uniform distribution. The mean of the real and imaginary parts of all constellation points is zero, and the variances are equal. n is the discrete time index.

[0066] Furthermore, the process of dividing the UFMC subcarriers into subbands in the frequency domain and the process of PTS dividing the frequency domain sequence into blocks are combined, that is, the block division steps of some transmission sequence methods are omitted. The subbands divided by the UFMC subcarriers are used as the sub-block sequences of PTS. After IFFT operation and filtering, they are multiplied and added with the phase rotation factor, and then sent to the channel for transmission.

[0067] S4 uses a hyperchaotic model to generate a chaotic sequence, and the chaotic sequence is processed to obtain the phase factor required by PTS.

[0068] In this embodiment, the hyperchaotic model is a cellular neural network (CNN) hyperchaotic model, which can be represented as:

[0069]

[0070] Where, f(x) j )=1 / 2(|x j +1|-|x j -1|)

[0071] Among them, j, a j x j S jk f(x) j The symbols ) represent the marker, threshold, constant, state variable, relationship parameters between variables, and cell output, respectively. To reduce the computational complexity of the system, and A jk All are 0.

[0072] By setting the relationship parameters between the variables in the dynamic model above, in this embodiment, the hyperchaotic model used for encryption is a fifth-order CNN hyperchaotic model, which can be given by the following formula:

[0073]

[0074] Where x1 to x5 represent the five initial parameters, and f(x4) represents the intermediate parameters. to These represent five output parameters, including the chaotic sequence. The value range is 1 to 4, corresponding to the above. to The four chaotic sequences, according to The value is used to select the corresponding chaotic sequence, and then the phase factor is generated.

[0075] The fifth-order CNN hyperchaotic model has two Lyapunov positive exponents, making it a hyperchaotic system with high security performance, strong real-time and continuous-time dynamic properties, and the ability to achieve chaotic behavior in three dimensions or even higher dimensions.

[0076] In this embodiment, the five initial parameters are set to 0.1, 0.2, 0.2, 0.2, and 0.2, respectively.

[0077] The masking vector for generating the phase rotation factor is selected from the chaotic sequence x5 generated by the fifth-order CNN hyperchaotic model:

[0078] Q = floor(mod(x5*10^15,5))

[0079] Where floor means rounding down to the nearest integer, mod means modulo function, x5 means chaotic sequence, and the generated Q value is 1 to 4, corresponding to chaotic sequence x1 to x4.

[0080] Phase factor b v It is generated from one of the chaotic sequences x1 to x4:

[0081] b v =binary2factor(floor(mod(X)) Q ,2),1), where Q∈{1,2,3,4}.

[0082] To facilitate hardware implementation, the range of phase factor values ​​is limited to {±1}, i.e.

[0083] b v ∈{+1,-1}.

[0084] S5, based on the time-domain sub-block sequence, multiplies the phase factor with the corresponding sub-band, and the resulting sub-bands are filtered by their respective filters and then added together to calculate the peak-to-average power ratio (PAPR).

[0085] When the phase factor is multiplied by the corresponding subband, the phase factor multiplied by the subcarriers within each subband is the same.

[0086] Specifically, each temporal sub-block sequence x of length M v It is necessary to first match it with its corresponding phase factor b. v Multiply the sequences, then add the B time-domain sub-block sequences, calculate their peak-to-average power ratio (PAPR), and record it in a vector.

[0087] After each sub-band is multiplied by a phase factor, the time-domain transmitted signal x(n) is the superposition of all sub-bands, as shown below:

[0088]

[0089] Where, x v It is a time-domain signal sequence.

[0090] The time-domain transmitted signal x(n) of a Universal Filtered Multicarrier (UFMC) is composed of the superposition of all subbands, each containing an equal number of independent subcarriers. The peak-to-average power ratio (PAPR) of the transmitted signal is used to represent its time-domain variation characteristics; its defined formula is:

[0091]

[0092] The complementary cumulative distribution function (CCDF) is used to represent the statistical characteristics of the peak-to-average power ratio (PAPR) in a multi-carrier system. It is defined as the probability that the PAPR in a multi-carrier transmission system exceeds a certain threshold value z. The CCDF is a continuous function, and it represents the sum of probabilities of all values ​​greater than a.

[0093]

[0094] Among them, adopt To optimize the CCDF, substituting into the above formula, we can obtain the minimum value of the CCDF:

[0095] CCDF opt =1-(1-e -γ ) N

[0096] S6. Circularly shift the sub-bands and repeat step S5 above. After traversing all cases, compare all peak-to-average power ratio (PAPR) values ​​and select the sub-band arrangement corresponding to the smallest PAPR value for signal transmission.

[0097] Figure 2 This is a detailed schematic diagram of the sub-band cyclic shift in an embodiment of the present invention.

[0098] like Figure 2 As shown, during cyclic shifting, each sub-band moves one position at a time as a whole, while the position of the phase factor remains unchanged, resulting in a different phase factor multiplied by the sub-band after each shift.

[0099] A vector is set up to record the peak-to-average power ratio (PAPR) value obtained by multiplying and adding the phase factor after the subband is cyclically shifted. Then, all PAPR values ​​are compared, and the subband arrangement corresponding to the smallest PAPR value is selected for signal transmission.

[0100] Figure 3 This is a schematic diagram of CCDF in an embodiment of the present invention, wherein the number of subcarriers is 1024, the number of subbands is 16, and each subband has 64 subcarriers.

[0101] like Figure 3As shown, this is a comparison chart of the PAPR reduction capability of the present invention in the UFMC system. By setting a signal without any PAPR reduction processing as a control, it can be seen that, under the same conditions, the signal applying the method of the present invention has a PAPR reduction of about 4 dB compared with the signal without PAPR reduction processing at CCDF=10-3.

[0102] The advantage of this invention is that the phase factor sequence can be obtained by directly setting up a chaotic system synchronized with the transmitter at the receiver, eliminating the need to send the phase factor sequence as sideband information to the receiver as in traditional methods. This significantly reduces signal redundancy and enhances bandwidth utilization. Simultaneously, the cyclic shifting of subbands disrupts the original arrangement order, greatly improving signal security. This invention exhibits excellent PAPR suppression without affecting the system's BER performance.

[0103] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An improved Partial Transmission Sequence (PTS) technique in a Universal Filtered Multicarrier (UFMC) system, characterized in that, Includes the following steps: S1, QAM modulation is performed on the acquired signal to be transmitted to obtain the modulated signal; S2, perform subband allocation and serial-to-parallel conversion on the modulated signal to obtain PTS group data for each subband; S3, perform N-point IFFT processing on the PTS grouped data of each sub-band and filter processing on the filters of each sub-band to obtain the time-domain sub-block sequence; S4, a chaotic sequence is generated using a hyperchaotic model, and the chaotic sequence is processed to obtain the phase factor required by PTS; S5. Based on the time-domain sub-block sequence, the phase factor is multiplied by the corresponding sub-band, and the resulting sub-bands are filtered by their respective filters and then added together to calculate the peak-to-average power ratio (PAPR). S6, the sub-band is cyclically shifted, and step S5 above is repeated. After traversing all cases, all peak-to-average power ratio (PAPR) values ​​are compared, and the sub-band arrangement corresponding to the smallest PAPR value is selected for signal transmission.

2. An improved PTS technique in the Universal Filtered Multicarrier (UFMC) system according to claim 1. Its features are: Step S2 includes the following sub-steps: S2.1, the sub-band allocation includes allocating multiple subcarriers to the sub-band. The UFMC system includes B sub-bands, each sub-band has M subcarriers, and the total number of subcarriers is N, i.e., N = B * M; each sub-band is allocated a filter. S2.2, PTS grouping is performed on the frequency domain subbands of the UFMC system to obtain PTS grouping data X = [X1, X2, X3, ..., X...]. N The PTS packet data satisfies Where v = 1, 2, ..., B, and B is the number of sub-bands.

3. An improved PTS technology in the Universal Filtered Multicarrier (UFMC) system according to claim 2, characterized in that: in, Step S3 includes the following sub-steps: S3.1, for the PTS packet data of the B subbands, after sequentially performing N-point IFFT transformation according to the UFMC transceiver structure, S is obtained. jj =[S j (0),S j (1),…,S j (N-1)] T j = (1, 2, ... B), S j After filtering by the aforementioned filter, the temporal sub-block sequence is obtained. x j =[x j (0),x j (1),…,x j (N+1-1)] T ,j=(1,2,...B); S3.2, the filter is a Chebyshev filter h with a filter length of L, and x(n) is the baseband equivalent discrete-time signal within a symbol time interval, i.e. Where n = 0, ..., N+L-1, and the input data X i (m) is a frequency domain subcarrier signal obtained by digitally modulating a bit stream of independent random variables with equal probability and uniform distribution. The mean of the real and imaginary parts of all constellation points is zero, and the variances are equal.

4. An improved PTS technology in the Universal Filtered Multicarrier (UFMC) system according to claim 3, characterized in that: in, In step S3.1: PTS needs to divide the frequency domain sequence X of length N into V non-overlapping frequency domain sub-block sequences X according to the block division rules. V ; Each of the segmented frequency domain sub-block sequences is multiplied by a complex phase factor b. v Add them together, and then perform an IFFT transformation to the time domain to obtain the final transmitted signal x, that is: Where, x v It is a time-domain signal sequence.

5. An improved PTS technology in the Universal Filtered Multicarrier (UFMC) system according to claim 4, characterized in that: in, In step S3.2: the process of dividing the UFMC subcarriers into subbands in the frequency domain and the process of PTS dividing the frequency domain sequence into blocks are combined, that is, the block division steps of some transmission sequence methods are omitted. The subbands divided by the UFMC subcarriers are used as the sub-block sequence of PTS. After IFFT operation and filtering, they are multiplied and added with the phase rotation factor, and then sent to the channel for transmission.

6. An improved PTS technique in the Universal Filtered Multicarrier (UFMC) system according to claim 1, characterized in that: in, In step S4: the hyperchaotic model is a cellular neural network (CNN) hyperchaotic model, and the CNN hyperchaotic model is represented as follows: in, Among them, j, a jj x jj S jjk f(x) jj The symbols ) represent the marker, threshold, constant, state variable, relationship parameters between variables, and cell output, respectively. and A jk All are 0.

7. An improved PTS technique in the Universal Filtered Multicarrier (UFMC) system according to claim 1, characterized in that: in, In step S4, the hyperchaotic model generates a chaotic sequence X1, and the phase factor is generated from the chaotic sequence. The phase factor b v =binary2factor(floor(mod(X1,2)),1).

8. An improved PTS technology in the Universal Filtered Multicarrier (UFMC) system according to claim 1, characterized in that: in, In step S5: when the phase factor is multiplied with the corresponding sub-band, the phase factor multiplied by the subcarrier in each sub-band is the same.

9. An improved PTS technique in the Universal Filtered Multicarrier (UFMC) system according to claim 1, characterized in that: in, In step S6: During the cyclic shift, each sub-band moves one position at a time as a whole, while the position of the phase factor remains unchanged.

10. An improved PTS technique in the Universal Filtered Multicarrier (UFMC) system according to claim 1, characterized in that: in, In step S6: Set a vector to record the peak-to-average power ratio (PAPR) value obtained by multiplying and adding the phase factor after the subband is cyclically shifted.

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