A physical layer secure transmission method for non-orthogonal FDM system

Abstract

A method for secure transmission of the physical layer of a non-orthogonal FDM system belongs to the field of wireless communication technology. The present invention solves the problem of poor security performance of physical layer transmission of a non-orthogonal FDM system. Under the premise of ensuring the high system throughput of the non-orthogonal FDM system, the present invention designs a transmission pattern array based on a random pattern principle, a pattern set principle or a minimum peak-to-average ratio principle, and performs decoding based on the transmission pattern array at the receiving end to improve the security performance of physical layer transmission of the non-orthogonal FDM system. The method of the present invention can be applied to secure transmission of the physical layer of a non-orthogonal FDM system.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless communications, and in particular relates to a physical layer security transmission method for a non-orthogonal FDM system. Background Art

[0002] With the combination of 5G communication networks and IoT technologies, the number of user communication demands and network access devices has increased dramatically. The efficient integration of intelligent applications in the network has brought challenges to cloud computing technology and resource allocation. Although it has a strong ability to process the massive data generated by the IoT cluster, the communication link for data transmission is limited by bandwidth. It is necessary to optimize the resource management and use of information interaction to meet the service quality requirements of IoT services at a lower cost and greater spectrum utilization. In addition, as a large number of personal terminals are loaded into the IoT cloud, privacy and security risks are also brought. The rising communication demand and limited frequency resources have prompted the research and development of higher throughput communication technologies. In response to the problem of limited spectrum resources, some corresponding methods have been proposed in terms of physical layer signal form, network architecture and information processing methods.

[0003] For traditional communication systems, single carrier or orthogonal frequency division multiplexing technology, etc., all meet the requirements of the orthogonal criterion. However, facing the higher system throughput requirements, the orthogonal system adopts higher-order modulation methods or performs waveform design to improve the spectrum efficiency; the former is more sensitive to the nonlinear interference of the device and has higher requirements for the device, while the latter cannot achieve the purpose of saving bandwidth and increasing the transmission rate within the signal bandwidth. In order to further improve the system throughput, non-orthogonal transmission systems came into being and broke through the spectral efficiency limitations of the orthogonal system. Due to its non-orthogonality, there is inter-symbol interference in the signal during transmission, and a detection algorithm or reconstruction algorithm with high computational complexity needs to be used at the receiving end to ensure the normal operation of the system. In addition, in order to prevent information leakage, transmission security is also an issue worth studying. By combining physical layer signal design with data processing methods, on the one hand, the requirements of higher throughput and higher spectral efficiency can be met, while at the same time, more flexible and safer signal transmission can be achieved.

[0004] Traditional orthogonal frequency division multiplexing (OFDM) signals are orthogonal signals and are also typical band-limited signals, that is, the signal information is concentrated in a part of the frequency domain. In order to further improve the throughput of the OFDM system, non-orthogonal FDM signals such as compressed OFDM signals (C-OFDM) and spectrally efficient FDM (SEFDM) signals are non-orthogonalized based on the OFDM system architecture. Due to different signal processing processes, band-limited signal reconstruction and nonlinear detection are used at the receiving end to ensure the normal operation of the system. In summary, although the non-orthogonal FDM system has certain advantages in improving the throughput of the OFDM system, its security protection in physical layer transmission still needs to be further improved, and the security performance of physical layer transmission is poor. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of poor security performance of physical layer transmission in a non-orthogonal FDM system while ensuring the high throughput of the non-orthogonal FDM system, and propose a physical layer security transmission method for a non-orthogonal FDM system.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] According to one aspect of the present invention, a physical layer security transmission method for a non-orthogonal FDM system is provided, the method specifically comprising the following steps:

[0008] On the sending end

[0009] Step 1: The signal source is mapped to obtain signal x, which is then modulated by OFDM and converted serially to obtain the symbol s of the OFDM signal. ori ,s ori =[s 0 ,...,s N-1 ] T , where s 0 Yes ori The first element in s N-1 Yes ori The Nth element in s, where N is ori The length of , the superscript T represents transpose;

[0010] Step 2: Generate a "transmit pattern array" Ψ and generate a transmit pattern pointer 'flag';

[0011] Step 3: According to the Ψ generated in step 2, ori Perform time domain interception to obtain the time domain interception result; the time domain interception process is expressed in matrix form as follows:

[0012] s=Ψ·s ori

[0013] Step 4: synthesize a data stream by combining several symbols s, then add the transmission pattern pointer 'flag' into the data stream to obtain the signal to be transmitted, and transmit the signal to be transmitted to the channel;

[0014] On the receiving end

[0015] Step 5, down-convert and synchronize the received signal to obtain a time domain signal; then extract the 'flag' from the time domain signal, and execute step 6 on the remaining data signal after extracting the 'flag';

[0016] Step 6: Oversample the data signal by γ times to obtain M 0 A time domain symbol r of length M m,ori ,m=1,2,…,M 0 , Represents γN C ×1-order vector set;

[0017] Step 7: For the time domain symbol r m,ori , according to the 'flag' information extracted in step 5, r is obtained m,ori The "sending pattern array" Ψ, and then according to Ψ to r m,ori Pad zero to get the signal r, r 1 ,r 2 ,…,r γN is the 1st, 2nd, ...γNth element in signal r, Represents a set of γN×1-order vectors;

[0018] The signal r is input into the extrapolator and the output signal Then the output signal Perform γ-fold downsampling in the time domain, and perform discrete Fourier transform on the downsampling result. The transform result then passes through the detector and parallel-to-serial conversion in sequence to finally obtain the decoded information;

[0019] Similarly, each time domain symbol obtained in step six is ​​processed.

[0020] According to another aspect of the present invention, a physical layer security transmission method for a non-orthogonal FDM system, the working process of the method at the transmitting end is:

[0021] Step 1: The signal source is mapped to obtain signal x, which is then modulated by OFDM and converted serially to obtain the symbol s of the OFDM signal. ori ,s ori =[s 0 ,…,s N-1 ] T , where s 0 Yes ori The first element in sN-1 Yes ori The Nth element in s, where N is ori The length of , the superscript T represents transpose;

[0022] Step 2: Generate a "transmit pattern array" Ψ and generate a transmit pattern pointer 'flag';

[0023] Step 3: According to the Ψ generated in step 2, ori Perform time domain interception to obtain the time domain interception result; the time domain interception process is expressed in matrix form as follows:

[0024] s=Ψ·s ori

[0025] Step 4: synthesize a plurality of symbols s into a data stream, then add a transmission pattern pointer 'flag' into the data stream to obtain a signal to be transmitted, and transmit the signal to be transmitted to the channel.

[0026] The beneficial effects of the present invention are:

[0027] Under the premise of ensuring the high system throughput of the non-orthogonal FDM system, the present invention designs the transmission pattern array based on the random pattern principle, the pattern set principle or the minimum peak-to-average ratio principle to improve the security of the system physical layer transmission. Compared with the existing non-orthogonal FDM system, the method of the present invention can greatly improve the security performance of the system physical layer transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart for generating a compressed OFDM signal;

[0029] Figure 2 It is a receiving end workflow diagram of the method of the present invention;

[0030] Figure 3 It is a working flow chart of the extrapolator in the present invention. DETAILED DESCRIPTION

[0031] Specific implementation method 1. Combination Figure 1 and Figure 2 This embodiment describes a method for secure physical layer transmission in a non-orthogonal FDM system, and the method specifically includes the following steps:

[0032] On the sending end

[0033] Step 1: The signal source is mapped to obtain signal x, which is then modulated by OFDM and converted serially to obtain the symbol s of the OFDM signal. ori ,s ori =[s 0 ,...,s N-1 ]T , where s 0 Yes ori The first element in s N-1 Yes ori The Nth element in s, where N is ori The length of , the superscript T represents transpose;

[0034] Step 2: Generate a "transmit pattern array" Ψ and generate a transmit pattern pointer 'flag';

[0035] Step 3: According to the Ψ generated in step 2, ori Perform time domain interception to obtain the time domain interception result; the time domain interception process is expressed in matrix form as follows:

[0036] s=Ψ·s ori

[0037] Step 4: synthesize a data stream by combining several symbols s, then add the transmission pattern pointer 'flag' into the data stream to obtain the signal to be transmitted, and transmit the signal to be transmitted to the channel;

[0038] On the receiving end

[0039] Step 5, down-convert and synchronize the received signal to obtain a time domain signal; then extract the 'flag' from the time domain signal, and execute step 6 on the remaining data signal after extracting the 'flag';

[0040] Step 6: Oversample the data signal by γ times to obtain M 0 A time domain symbol r of length M m,ori ,m=1,2,…,M 0 , Represents γN C ×1-order vector set;

[0041] For example: γ=4,8,16,..., when applied, its specific value needs to be designed according to the system's requirements for processing time and the properties of components;

[0042] Step 7: For the time domain symbol r m,ori , according to the 'flag' information extracted in step 5, r is obtained m,ori The "sending pattern array" Ψ, and then according to Ψ to r m,ori Pad zero to get the signal r, r 1 ,r 2 ,...,r γN is the 1st, 2nd, ...γNth element in signal r, Represents a set of γN×1-order vectors;

[0043] Input the signal r into the extrapolator and output the signal Then the output signal Perform γ-fold downsampling in the time domain, and perform discrete Fourier transform on the downsampling result. The transform result then passes through the detector and parallel-to-serial conversion in sequence to finally obtain the decoded information;

[0044] Similarly, each time domain symbol obtained in step six is ​​processed.

[0045] The entire sending and receiving process of the method of the present invention is based on a compressed OFDM system in a non-orthogonal FDM system, and can also be applied to other non-orthogonal FDM systems under the premise of taking the system architecture into consideration.

[0046] The transmission pattern array generation method of the present invention can be performed according to the rules of specific implementation modes 2, 3 or 4, but is not limited to the rules of specific implementation modes 2, 3 or 4. The security of system physical layer transmission is improved by designing the transmission pattern array.

[0047] Specific implementation method 2: This implementation method is different from the specific implementation method 1 in that the specific process of step 2 is as follows:

[0048] Step 1: Unify the symbol period T of the compressed OFDM signal at both ends of the transmitter and receiver C Under the premise of , calculate the compression ratio α:

[0049] α=T C / T

[0050] Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal;

[0051] Step 2: Calculate the number of points N of each symbol of the compressed OFDM signal according to the compression ratio α C :

[0052] N C =α·N

[0053] Step 3: Generate an N×1 random vector containing only 0 and 1 in, Represents a set of N×1 vectors, and in the random vector The number of elements "1" in is N C ;

[0054] Step 4: The random vector generated in step 3 Diagonalize to generate the "send pattern array" And generate the sending pattern pointer 'flag'.

[0055] This implementation generates a "transmitting pattern array" based on a random pattern principle.

[0056] Specific implementation method three: This implementation method is different from the specific implementation method one in that the specific process of step two is as follows:

[0057] Step 1: Unify the symbol period T of the compressed OFDM signal at both ends of the transmitter and receiver C Under the premise of , calculate the compression ratio α:

[0058] α=T C / T

[0059] Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal;

[0060] Step 2: According to the compression ratio α obtained in step 1, a transmission pattern array Ψ is selected from a pattern set known to both the transmitting and receiving ends, and a transmission pattern pointer 'flag' is recorded.

[0061] This implementation generates a "transmit pattern array" based on a pattern set principle.

[0062] Specific implementation method 4: This implementation method is different from the specific implementation method 1 in that the specific process of step 2 is as follows:

[0063] Step 1: Unify the symbol period T of the compressed OFDM signal at both ends of the transmitter and receiver C Under the premise of , calculate the compression ratio α:

[0064] α=T C / T

[0065] Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal;

[0066] Step 2: Calculate the number of points N of each symbol of the compressed OFDM signal according to the compression ratio α C :

[0067] N C =αN

[0068] Step 3: According to N C And the minimum peak-to-average ratio principle, we get the transmission pattern support set sequence χ, Among them, χ 1 is the first support set in the sequence, χ 2 is the second support set in the sequence, is the Nth c Support sets;

[0069] And the sent pattern support set sequence χ satisfies:

[0070]

[0071]

[0072] in, Represents N c ×1-order vector set, n∈χ,s ori (n) represents s ori The nth element in , |·| represents the absolute value, and PAPR represents the peak-to-average ratio;

[0073] Step 4: Generate a vector containing only 0 and 1 based on χ in,

[0074] Step 5: The random vector generated in step 4 Diagonalize to generate the "send pattern array" And generate the sending pattern pointer 'flag'.

[0075] This implementation method generates a "transmission pattern array" based on the minimum peak-to-average ratio principle.

[0076] Specific implementation method five: Combination Figure 3 The present embodiment is different from the second, third or fourth embodiment in that the signal r is input into the extrapolator and the output signal The specific process is:

[0077] Step 1), initialize the number of iterations i = 1, initialize the signal to be extrapolated y 0 = r, set the maximum number of iterations to ITE;

[0078] Step 2), performing discrete Fourier transform on the extrapolated signal to obtain a transformation result;

[0079] Step 3) Pass the transformation result obtained in step 2) through a low-pass filter H c , the passband bandwidth of the low-pass filter is the OFDM signal bandwidth;

[0080] Step 4), performing an inverse discrete Fourier transform on the signal obtained in step 3) to obtain a new time domain signal;

[0081] Step 5), using the signal to be extrapolated to replace the corresponding sampling points in the new time domain signal, and then obtaining the extrapolated signal of this iteration according to the transmitted pattern array Ψ;

[0082] Step 6), taking the extrapolated signal obtained in step 5) as the signal to be extrapolated, and returning to step 2);

[0083] Step 7) Repeat the process from step 2) to step 6) until the maximum number of iterations is reached and stop the iteration. ITE As output signal

[0084] For example, taking the first iteration:

[0085] Treat the extrapolated signal y 0 Perform discrete Fourier transform;

[0086] The transformed signal is passed through a low-pass filter H c , the passband bandwidth is the OFDM signal bandwidth;

[0087] Perform inverse discrete Fourier transform on the filtered signal to obtain a new time domain signal;

[0088] According to the transmitted pattern Ψ, the extrapolated signal y 0 Replace some sampling points in the new time domain signal to obtain the extrapolated signal of the first iteration, which can be expressed as:

[0089]

[0090] Where I represents the unit matrix of the same order as the transmitted pattern Ψ, represents the Fourier transform matrix, represents the inverse Fourier transform matrix;

[0091] y 1 As the signal to be extrapolated in the next iteration.

[0092] Specific implementation method 6: This implementation method is different from the specific implementation method 5 in that the extrapolated signal is:

[0093] For the i-th iteration:

[0094]

[0095] Among them, y i represents the extrapolated signal obtained at the i-th iteration, y i-1 represents the extrapolated signal obtained at the i-1th iteration, I represents the unit matrix of the same order as the transmitted pattern array Ψ, represents the Fourier transform matrix, Represents the inverse Fourier transform matrix.

[0096] Specific implementation method VII. Combination Figure 1 This embodiment describes a method for secure physical layer transmission in a non-orthogonal FDM system, and the working process of the method at the transmitting end is as follows:

[0097] Step 1: The signal source is mapped to obtain signal x, which is then modulated by OFDM and converted serially to obtain the symbol s of the OFDM signal. ori ,s ori =[s 0 ,...,s N-1 ] T , where s 0 Yes ori The first element in s N-1 Yes ori The Nth element in s, where N is ori The length of , the superscript T represents transpose;

[0098] Step 2: Generate a "transmit pattern array" Ψ and generate a transmit pattern pointer 'flag';

[0099] Step 3: According to the Ψ generated in step 2, ori Perform time domain interception to obtain the time domain interception result; the time domain interception process is expressed in matrix form as follows:

[0100] s=Ψ·s ori

[0101] Step 4: synthesize a plurality of symbols s into a data stream, then add a transmission pattern pointer 'flag' into the data stream to obtain a signal to be transmitted, and transmit the signal to be transmitted to the channel.

[0102] Specific implementation eight: This implementation is different from specific implementation seven in that the specific process of step two is as follows:

[0103] Step 1: Unify the symbol period T of the compressed OFDM signal at both ends of the transmitter and receiver C Under the premise of , calculate the compression ratio α:

[0104] α=T C / T

[0105] Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal;

[0106] Step 2: Calculate the number of points N of each symbol of the compressed OFDM signal according to the compression ratio α C :

[0107] N C =α·N

[0108] Step 3: Generate an N×1 random vector containing only 0 and 1 in, Represents a set of N×1 vectors, and in the random vector The number of elements "1" in is N C ;

[0109] Step 4: The random vector generated in step 3 Diagonalize to generate the "send pattern array" And generate the sending pattern pointer 'flag'.

[0110] This implementation generates a "transmitting pattern array" based on a random pattern principle.

[0111] Specific implementation method 9: This implementation method is different from specific implementation method 7 in that the specific process of step 2 is as follows:

[0112] Step 1: Unify the symbol period T of the compressed OFDM signal at both ends of the transmitter and receiver C Under the premise of , calculate the compression ratio α:

[0113] α=T C / T

[0114] Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal;

[0115] Step 2: According to the compression ratio α obtained in step 1, a transmission pattern array Ψ is selected from a pattern set known to both the transmitting and receiving ends, and a transmission pattern pointer 'flag' is recorded.

[0116] This implementation generates a "transmit pattern array" based on a pattern set principle.

[0117] Specific implementation method ten: This implementation method is different from specific implementation method seven in that the specific process of step two is as follows:

[0118] Step 1: Unify the symbol period T of the compressed OFDM signal at both ends of the transmitter and receiver C Under the premise of , calculate the compression ratio α:

[0119] α=T C / T

[0120] Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal;

[0121] Step 2: Calculate the number of points N of each symbol of the compressed OFDM signal according to the compression ratio α C :

[0122] N C =α·N

[0123] Step 3: According to N C And the minimum peak-to-average ratio principle, we get the transmission pattern support set sequence χ, Among them, χ 1 is the first support set in the sequence, χ 2 is the second support set in the sequence, is the Nth c Support sets;

[0124] And the sent pattern support set sequence χ satisfies:

[0125]

[0126]

[0127] in, Represents N c ×1-order vector set, n∈χ,s ori (n) represents s ori The nth element in , |·| represents the absolute value, and PAPR represents the peak-to-average ratio;

[0128] Step 4: Generate a vector containing only 0 and 1 based on χ in, n∈χ;

[0129] Step 5: The random vector generated in step 4 Diagonalize to generate the "send pattern array" And generate the sending pattern pointer 'flag'.

[0130] This implementation method generates a "transmission pattern array" based on the minimum peak-to-average ratio principle.

[0131] The above calculation examples of the present invention are only used to explain the calculation model and calculation process of the present invention in detail, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A physical layer secure transmission method for a non-orthogonal FDM system. It is characterized in that The method specifically comprises the following steps: On the sending end Step 1: The signal source is mapped to obtain signal x, which is then modulated by OFDM and converted serially to obtain the symbol s of the OFDM signal. ori ,s ori =[s 0 ,…,s N-1 ] T , where s 0 Yes ori The first element in s N-1 Yes ori The Nth element in s, where N is ori The length of , the superscript T represents transpose; Step 2: Generate a "send pattern array" Ψ and generate a send pattern pointer 'flag'; The specific process of step 2 is as follows: Step 1: Calculate the compression ratio α: α=T C / T Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal; Step 2: Calculate the number of points N of each symbol of the compressed OFDM signal according to the compression ratio α C : N C =α·N Step 3: Generate an N×1 random vector containing only 0 and 1 in, represents a set of N×1 vectors, and in the random vector The number of elements "1" in is N C ; Step 4: The random vector generated in step 3 Diagonalize to generate the "send pattern array" And generate the sending pattern pointer 'flag'; Step 3: According to the Ψ generated in step 2, ori Perform time domain interception to obtain the time domain interception result; the time domain interception process is expressed in matrix form as follows: s=Ψ·s ori Step 4: synthesize a data stream by combining several symbols s, then add the transmission pattern pointer 'flag' into the data stream to obtain the signal to be transmitted, and transmit the signal to be transmitted to the channel; On the receiving end Step 5, down-convert and synchronize the received signal to obtain a time domain signal; then extract the 'flag' from the time domain signal, and execute step 6 on the remaining data signal after extracting the 'flag'; Step 6: Oversample the data signal by γ times to obtain M 0 A time domain symbol r of length M m,ori ,m=1,2,…,M 0 , Represents γN C ×1-order vector set; Step 7: For the time-domain symbol r m,ori , obtain the "transmission pattern array" Ψ of r m,ori according to the 'flag' information extracted in Step 5, and then zero-pad r m,ori to obtain the signal r, r 1 , r 2 , …, r γN are the 1st, 2nd, …, γNth elements in the signal r, representing the set of γN×1 order vectors; The signal r is input into the extrapolator and the output signal Then the output signal Perform γ-fold downsampling in the time domain, and perform discrete Fourier transform on the downsampling result. The transform result then passes through the detector and parallel-to-serial conversion in sequence to finally obtain the decoded information; Similarly, each time domain symbol obtained in step six is ​​processed.

2. A method for secure transmission of physical layer of non-orthogonal FDM system according to claim 1, It is characterized in that The step 2 may also be: Step 1: Calculate the compression ratio α: α=T C / T Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal; Step 2: According to the compression ratio α obtained in step 1, a transmission pattern array Ψ is selected from a pattern set known to both the transmitting and receiving ends, and a transmission pattern pointer 'flag' is recorded.

3. A method for secure transmission of physical layer of non-orthogonal FDM system according to claim 1, It is characterized in that The step 2 may also be: Step 1: Calculate the compression ratio α: α=T C / T Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal; Step 2: Calculate the number of points N of each symbol of the compressed OFDM signal according to the compression ratio α C : N C =α·N Step 3: According to N C And the minimum peak-to-average ratio principle, we get the transmission pattern support set sequence χ, Among them, χ 1 is the first support set in the sequence, χ 2 is the second support set in the sequence, is the Nth c Support sets; And the sent pattern support set sequence χ satisfies: in, Represents N c ×1-order vector set, n∈χ,s ori (n) represents s ori The nth element in , |·| represents the absolute value, and PAPR represents the peak-to-average ratio; Step 4: Generate a vector containing only 0 and 1 based on χ wherein, Step 5: The random vector generated in step 4 Diagonalize to generate the "send pattern array" And generate the sending pattern pointer 'flag'.

4. A method for secure transmission of physical layer of non-orthogonal FDM system according to claim 1, 2 or 3, It is characterized in that The signal r is input into the extrapolator, and the output signal The specific process is: Step 1), initialize the number of iterations i = 1, initialize the signal to be extrapolated y 0 = r, set the maximum number of iterations to ITE; Step 2), performing discrete Fourier transform on the extrapolated signal to obtain a transformation result; Step 3) Pass the transformation result obtained in step 2) through a low-pass filter H c , the passband bandwidth of the low-pass filter is the OFDM signal bandwidth; Step 4), performing an inverse discrete Fourier transform on the signal obtained in step 3) to obtain a new time domain signal; Step 5), using the signal to be extrapolated to replace the corresponding sampling points in the new time domain signal, and then obtaining the extrapolated signal of this iteration according to the transmitted pattern array Ψ; Step 6), taking the extrapolated signal obtained in step 5) as the signal to be extrapolated, and returning to step 2); Step 7) Repeat the process from step 2) to step 6) until the maximum number of iterations is reached and stop the iteration. ITE As output signal 5. A method for secure transmission of physical layer of non-orthogonal FDM system according to claim 4, It is characterized in that The extrapolated signal is: For the i-th iteration: Among them, y i represents the extrapolated signal obtained at the i-th iteration, y i-1 represents the extrapolated signal obtained at the i-1th iteration, I represents the unit matrix of the same order as the transmitted pattern array Ψ, represents the Fourier transform matrix, Represents the inverse Fourier transform matrix.

6. A physical layer security transmission method for non-orthogonal FDM system, It is characterized in that The working process of the method at the sending end is: Step 1: The signal source is mapped to obtain signal x, which is then modulated by OFDM and converted serially to obtain the symbol s of the OFDM signal. ori ,s ori =[s 0 ,...,s N-1 ] T , where s 0 Yes ori The first element in s N-1 Yes ori The Nth element in s, where N is ori The length of , the superscript T represents transpose; Step 2: Generate a "send pattern array" Ψ and generate a send pattern pointer 'flag'; The specific process of step 2 is as follows: Step 1: Calculate the compression ratio α: α=T C / T Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of the compressed OFDM signal; Step 2: Calculate the number of points N of each symbol of the compressed OFDM signal according to the compression ratio α C : N C =α·N Step 3: Generate an N×1 random vector containing only 0 and 1 in, Represents a set of N×1 vectors, and in the random vector The number of elements "1" in is N C ; Step 4: The random vector generated in step 3 Diagonalize to generate the "send pattern array" And generate the sending pattern pointer 'flag'; Step 3: According to the Ψ generated in step 2, ori Perform time domain interception to obtain the time domain interception result; the time domain interception process is expressed in matrix form as follows: s=Ψ·s ori Step 4: synthesize a plurality of symbols s into a data stream, then add a transmission pattern pointer 'flag' into the data stream to obtain a signal to be transmitted, and transmit the signal to be transmitted to the channel.

7. A method for secure transmission of physical layer of non-orthogonal FDM system according to claim 6, It is characterized in that The step 2 may also be: Step 1: Calculate the compression ratio α: α=T C / T Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of the compressed OFDM signal; Step 2: According to the compression ratio α obtained in step 1, a transmission pattern array Ψ is selected from a pattern set known to both the transmitting and receiving ends, and a transmission pattern pointer 'flag' is recorded.

8. A method for secure transmission of physical layer of non-orthogonal FDM system according to claim 6, It is characterized in that The step 2 may also be: Step 1: Calculate the compression ratio α: α = T C / T Where T is the symbol s of the OFDM signal ori The symbol period, T C is the symbol period of compressed OFDM signal; Step 2: Calculate the number of points N of each symbol of the compressed OFDM signal according to the compression ratio α C : N C =α·N Step 3: According to N C And the minimum peak-to-average ratio principle, we get the transmission pattern support set sequence χ, Among them, χ 1 is the first support set in the sequence, χ 2 is the second support set in the sequence, is the Nth c Support sets; And the sent pattern support set sequence χ satisfies: in, Represents N c ×1-order vector set, n∈χ,s ori (n) represents s ori The nth element in , |·| represents the absolute value, and PAPR represents the peak-to-average ratio; Step 4: Generate a vector containing only 0 and 1 based on χ in, Step 5: The random vector generated in step 4 Diagonalize to generate the "send pattern array" And generate the sending pattern pointer 'flag'.

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