Transform domain wireless physical layer secure transmission method based on RIS intelligent regulation and control

Abstract

The invention discloses a transform domain wireless physical layer secure transmission method based on RIS intelligent regulation and control, and relates to the field of wireless communication system physical layer secure transmission. In order to solve the security problem of physical layer transmission, a frame synchronization head, a pilot frequency, a receiving end transformation order and a sending end frame structure of an encrypted signal are designed by utilizing multi-term weighted fractional Fourier transform based on RIS intelligent regulation and control, and a security transmission architecture of spatial domain intelligent beam regulation and baseband transmitting and receiving transformation parameter mutual difference is provided. The method comprises the following steps: carrying out order M-term weighted fractional Fourier transform on a signal at a sending end, and carrying out-order N-term weighted fractional Fourier transform on a signal at a receiving end; and the whole wireless secure transmission process is completed. The method can prevent an eavesdropper from exposing user information by knowing a transmitting end transformation order, carries out directional protection on a transformation domain signal in a spatial domain, and further improves the safety transmission capability of a base band.

Description

Technical Field

[0001] This invention relates to the field of secure physical layer transmission in wireless communication systems, and specifically to a transform domain secure physical layer transmission method based on RIS intelligent control. Background Technology

[0002] Traditional transform domain methods mostly utilize only time and frequency domain resources. While ensuring transmission reliability, they cannot further guarantee secure transmission, necessitating the exploration of additional resources to enhance physical layer secure transmission capabilities. Furthermore, traditional weighted transform domain physical layer secure transmission methods primarily utilize feature hiding of transform domain signals to achieve secure transmission. However, this method requires both the transmitting and receiving ends to know the transform parameters, and these parameters must be consistent for correct signal demodulation. This means that if the transmitting end's transform parameters are deciphered, user information will be completely exposed. Therefore, a wireless physical layer secure transmission method is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to address the security issues of physical layer transmission. By utilizing multi-weighted fractional Fourier transform based on RIS intelligent control, a transmitter frame structure is designed, and a secure transmission architecture of "spatial intelligent beam control + baseband transmit and receive transformation parameters with different characteristics" is proposed and applied to wireless communication systems.

[0004] The technical solution adopted in this invention is as follows:

[0005] A transform-domain wireless physical layer secure transmission method based on RIS intelligent regulation, comprising the following steps at the transmitting end:

[0006] Step a1: The raw data first undergoes baseband mapping to obtain the modulated signal;

[0007] Step a2: Perform a multinomial weighted fractional Fourier transform on the signal obtained in step a1 to obtain the transformed signal; where the transform order is... Over the entire real number field, the number of transformation terms M can be chosen such that M > 3, and Z is an integer field;

[0008] Step a3: Digitally frame the signal obtained in step a2. The frame structure includes a frame synchronization header, pilot, and receiver transform order connected in sequence. The signal obtained in step a2; the frame synchronization header and pilot are both known information at both the transmitting and receiving ends;

[0009] Step a4: Perform digital-to-analog conversion on the digital framed signal obtained in step a3 to obtain the digital-to-analog converted signal;

[0010] Step a5: Digitally up-convert the signal obtained in step a4 to obtain the transmitted signal;

[0011] Step a6: The transmitted signal from step a5 is sent to the RIS metasurface through the directional antenna of the transmitting end, and the reflected signal from the RIS metasurface is aligned with the directional antenna of the receiving end.

[0012] The receiving end includes the following steps:

[0013] Step b1: The directional antenna at the receiving end receives the reflected signal from the RIS metasurface, and then performs digital down-conversion and analog-to-digital conversion on the received signal;

[0014] Step b2: For the signal obtained in step b1, use the autocorrelation method to find the maximum correlation value, perform frame synchronization header correlation operation, and obtain the synchronization signal;

[0015] Step b3: The synchronization signal obtained in step b2 is used for RIS signal estimation and feedback using pilot signals to assist beam control;

[0016] Step b4: Take the signal obtained in step b3 and transform it according to the receiver's transformation order. Perform - on the encrypted signal The decrypted signal is obtained by performing an N-WFRFT transform of order 3; N>3, and N Z is an integer field;

[0017] Step b5: Perform data demapping on the decrypted signal obtained in step b4 to obtain the demapped signal;

[0018] Step b6: Process the demapped signal obtained in step b5, output the result, and complete the secure wireless physical layer transmission based on RIS intelligent control in the transform domain.

[0019] Further, in step a2 The specific steps of the M-WFRFT transform are as follows:

[0020] ;

[0021] in, The signal obtained in step a1 is the modulated data. express Multinomial weighted fractional Fourier transform operator of order 1 Indicates the first The term is a multinomial weighted coefficient, where i is the imaginary unit. express The 4-WFRFT of order 1 can be represented as follows:

[0022] ;

[0023] in, express The four-term weighted fractional Fourier transform of order, express Fourier transform operator of order 1, This represents the coefficients of the 4-WFRFT.

[0024] Furthermore, in the frame structure of step a3, the frame synchronization header is designed using a 64-bit pseudo-random sequence; the pilot design uses a 128-bit pseudo-random sequence for RIS beam alignment and channel estimation; and the receiver's transformation order is designed to use 32 bits to represent the demodulation order, and the receiver's transformation order... The value satisfies .

[0025] Furthermore, the RIS metasurface is selected as a passive RIS.

[0026] The present invention has the following advantages over the prior art:

[0027] 1. The transform orders of the signals at the transmitting and receiving ends are inconsistent to prevent eavesdroppers from knowing the transform order at the transmitting end and exposing user information;

[0028] 2. Air-to-ground directional beamforming can further provide directional protection for transform-domain signals in the spatial domain;

[0029] 3. For RIS communication systems, the presence of transform domain signals further enhances the baseband secure transmission capability;

[0030] 4. The secure transmission architecture of this invention does not make too many changes to the original transform domain system, and the system has strong compatibility. Attached Figure Description

[0031] Figure 1 This invention provides a secure transmission architecture for the wireless physical layer based on RIS intelligent regulation in the transform domain.

[0032] Figure 2 This refers to the frame structure design of the sending end in this invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0034] A transform-domain wireless physical layer secure transmission method based on RIS intelligent regulation, such as Figure 1 As shown, it includes the following steps:

[0035] Sending end operation process:

[0036] Step 1: The raw data is first mapped by the data baseband to obtain the modulated signal;

[0037] Step 2: Process the signal obtained in Step 1 The M-WFRFT (M-WFFT) of order M requires manual selection of the transform order and the number of transform terms. The transformation terms can be arbitrarily chosen over the entire real number field, and the number M of transformation terms satisfies M>3, and The transformed signal is obtained.

[0038] Among them, communication signals are performed The specific steps of the M-WFRFT transform are as follows: using the signal For example, of The M-WFRFT transform of order 1 is represented as follows:

[0039] ;

[0040] in, The signal obtained in step 1 is the modulated data. express Multinomial weighted fractional Fourier transform operator of order 1 Indicates the first The term is a multinomial weighted coefficient, where i is the imaginary unit. express The 4-WFRFT of order 1 can be represented as follows:

[0041] ;

[0042] in, express The four-term weighted fractional Fourier transform of order, express Fourier transform operator of order 1, This represents the coefficients of the 4-WFRFT.

[0043] Step 3: Digitize the signal obtained in Step 2 into digital frames. The frame structure design is as follows: Figure 2 As shown, the framed signal is obtained, where the frame synchronization header in the frame structure is composed of a 64-bit pseudo-random code; the demodulation order after the frame synchronization header and pilot sequence (128 bits) is... Modulation order at the transmitting end Choose the formula that satisfies Therefore, the number of transformation terms at the receiving end and the transmitting end need to be different to increase the secure transmission performance. Here, 32 bits are chosen to represent the demodulation order.

[0044] Step 4: Perform digital-to-analog conversion (D / A conversion) on the signal obtained in Step 3 to obtain the signal after digital-to-analog conversion;

[0045] Step 5: Digitally up-convert the signal obtained in Step 4 to obtain the transmitted signal;

[0046] Step 6: The signal transmitted in Step 5 is sent to the RIS metasurface through a directional antenna. The reflected signal from the RIS metasurface is aligned with the directional antenna at the receiving end. Here, the focus is on utilizing the secure air interface transmission capability of RIS beam modulation. As for issues such as channel estimation and beam alignment based on RIS, existing methods will be used, and this invention will not elaborate further.

[0047] The operation process of the receiving end

[0048] Step 7: Digitally downconvert the signal obtained from the receiving end in Step 6 to obtain a digital downconverted signal;

[0049] Step 8: Perform frame synchronization header correlation operation on the signal obtained in step 7. Since the receiver knows the frame synchronization header, the autocorrelation method can be used to find the maximum correlation value and obtain the synchronization signal.

[0050] Step 9: Use the pilot signal to perform RIS signal estimation and feedback on the synchronization signal obtained in step 8 to assist in beam control. This step is a routine operation and will not be repeated.

[0051] Step 10: Select the first 32 bits of the pilot signal obtained in Step 9 as the transform order. Perform - on the encrypted signal The decrypted signal is obtained by performing an N-term weighted fractional Fourier transform (N-WFRFT) of order N; the specific calculation process can be found in the calculation formula in step 2; N>3, and N Z is an integer field;

[0052] Step 11: Perform data demapping on the decrypted signal obtained in Step 10 to obtain the demapped signal;

[0053] Step 12: Process the demapped signal obtained in Step 11, output the result, and complete the entire wireless secure transmission process.

[0054] Step 3 involves designing a frame structure with distinct transmit and receive keys. This frame structure consists of four parts: the first part is the frame synchronization header design, where a 64-bit pseudo-random sequence is recommended, as it serves as the synchronization code for the receiver. The second part is the pilot design, where a 128-bit pseudo-random sequence is recommended, primarily used for RIS beam alignment and channel estimation. The third part is the receiver's transform order design, where a 32-bit representation of the demodulation order is chosen. This invention eliminates the need to transmit the transmitter's transform order over the air interface, instead transmitting only the receiver's transform order. This ensures that even if a non-cooperative party intercepts the transmitted transform order, they cannot decipher the information. The receiver's transform order... Transform order of the transmitting end satisfy From this point onward, the overhead for synchronization and pilot signals in this frame structure totals 224 bits; the fourth part is the data processed by the transmitting end. The signal after the M-WFRFT transformation is the encrypted information sent by the transmitter.

[0055] Step 6 is crucial for achieving dual protection of the "baseband + spatial domain" by combining the transform domain signal with the RIS metasurface. Here, a passive RIS metasurface is chosen, primarily to reduce system power consumption and lower the risk of signal exposure. The pointing of the RIS is controlled by a controller, which can deploy the RIS at different positions and set the angle according to user needs. For example, if the incident wave is at 30 degrees, the beam can be adjusted to 60 degrees after passing through the RIS.

[0056] In recent years, with the development of 6G mobile communication technology, intelligent metasurfaces (RIS) have shown outstanding capabilities in the utilization of spatial resources as an emerging communication technology. This invention combines transform domain technology and RIS technology to extend transform domain physical layer secure transmission technology to the spatial domain and improve the physical layer secure transmission capability.

[0057] Due to the signal reflection effect of RIS in signal-obstructed environments, this invention, combined with the deployment and angle adjustment capabilities of RIS, is also applicable to physical layer secure transmission scenarios in obstructed environments.

[0058] Those skilled in the art will recognize that the described embodiments are intended to help readers understand the principles of the invention and should be understood as not limiting the scope of protection of the invention to the described embodiments. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of the claims of the invention.

Claims

1. A transform-domain wireless physical layer secure transmission method based on RIS intelligent regulation, characterized in that, The sending end includes the following steps: Step a1: The raw data first undergoes baseband mapping to obtain the modulated signal; Step a2: Process the signal obtained in step a1. The transformed signal is obtained by performing a first-order M-WFRFT transform; where the transform order is... Over the entire real number field, the number of transformation terms M can be chosen such that M > 3, and Z is an integer field; Step a3: Digitally frame the signal obtained in step a2. The frame structure includes a frame synchronization header, pilot, and receiver transform order connected in sequence. The signal obtained in step a2; the frame synchronization header and pilot are both known information at both the transmitting and receiving ends; Step a4: Perform digital-to-analog conversion on the digital framed signal obtained in step a3 to obtain the digital-to-analog converted signal; Step a5: Digitally up-convert the signal obtained in step a4 to obtain the transmitted signal; Step a6: The transmitted signal from step a5 is sent to the RIS metasurface through the directional antenna of the transmitting end, and the reflected signal from the RIS metasurface is aligned with the directional antenna of the receiving end. The receiving end includes the following steps: Step b1: The directional antenna at the receiving end receives the reflected signal from the RIS metasurface, and then performs digital down-conversion and analog-to-digital conversion on the received signal; Step b2: For the signal obtained in step b1, use the autocorrelation method to find the maximum correlation value, perform frame synchronization header correlation operation, and obtain the synchronization signal; Step b3: The synchronization signal obtained in step b2 is used for RIS signal estimation and feedback using pilot signals to assist beam control; Step b4: Take the signal obtained in step b3 and transform it according to the receiver's transformation order. Perform - on the encrypted signal The decrypted signal is obtained by performing an N-WFRFT transform of order 3; N>3, and N Z is an integer field; Step b5: Perform data demapping on the decrypted signal obtained in step b4 to obtain the demapped signal; Step b6: Process the demapped signal obtained in step b5, output the result, and complete the secure wireless physical layer transmission based on RIS intelligent control in the transform domain.

2. The transform domain wireless physical layer secure transmission method based on RIS intelligent regulation according to claim 1, characterized in that, In step a2 The specific steps of the M-WFRFT transform are as follows: ； in, The signal obtained in step a1 is the modulated data. express Multinomial weighted fractional Fourier transform operator of order 1 Indicates the first The term is a multinomial weighted coefficient, where i is the imaginary unit. express The 4-WFRFT of order 1 can be represented as follows: ； in, express The four-term weighted fractional Fourier transform of order , express Fourier transform operator of order 1, This represents the coefficients of the 4-WFRFT.

3. The transform domain wireless physical layer secure transmission method based on RIS intelligent regulation according to claim 1, characterized in that, In the frame structure of step a3, the frame synchronization header is designed with a 64-bit pseudo-random sequence; the pilot design uses a 128-bit pseudo-random sequence for RIS beam alignment and channel estimation; and the receiver's transformation order is designed to use 32 bits to represent the demodulation order, and the receiver's transformation order... The value satisfies .

4. The transform domain wireless physical layer secure transmission method based on RIS intelligent regulation according to claim 1, characterized in that, RIS metasurfaces are selected for passive RIS.

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