A multi-frequency phased array based rotating beam physical layer security transmission system and method

Abstract

The application provides a rotating beam physical layer security transmission system and method based on a multi-frequency phased array, relates to the technical field of wireless communication physical layer security, and aims to solve the eavesdropping risk caused by the fixed main lobe direction of the traditional directional beam forming technology.The application realizes the rotation of the beam around the target user by introducing a frequency offset increment in the multi-frequency phased array, combines a randomization technology of random reverse side lobes, designs an adaptive control algorithm for the eavesdroppers with known positions and unknown positions respectively, makes the target user keep a stable signal-to-noise ratio, and significantly reduces the signal-to-noise ratio of the eavesdroppers.The application effectively solves the interception and cracking problem caused by the broadcast characteristics of wireless signals, greatly improves the reliability and anti-eavesdropping ability of the physical layer security transmission, and is suitable for high-speed wireless communication scenes such as millimeter waves.

Description

Technical Field

[0001] This invention relates to the field of physical layer security technology in wireless communication, specifically to a rotating beam physical layer security transmission system and method based on a multi-frequency phased array, applicable to wireless communication scenarios with high security requirements such as millimeter waves. Background Technology

[0002] Radio waves have inherent broadcast characteristics during transmission through space, making encrypted information modulated into radio signals highly susceptible to interception by unauthorized eavesdroppers as it propagates in physical space. With the increasing computing power of high-performance computers, intercepted encrypted information faces the risk of being brute-force cracked, posing a serious security threat to the transmission of confidential information in wireless communication systems.

[0003] To address the physical layer security issues arising from the broadcast characteristics of wireless signals, traditional solutions employ directional beamforming combined with beamside lobe randomization. This technology utilizes the signal convergence effect of a large-scale antenna array to form a directional transmission beam, significantly enhancing the signal amplitude in the main lobe direction while substantially attenuating the signal amplitude in the sidelobe direction. This design allows target users within the main lobe coverage area to efficiently receive signals, while eavesdroppers in the sidelobe region only receive weak, leaked signals, thus reducing the risk of confidential information leakage. When the eavesdropper is not located in the main lobe transmission direction, it ensures high physical layer security transmission performance.

[0004] However, traditional directional beamforming technology has inherent flaws: the direction of the main lobe is always fixed, and when the target user's location is determined, the transmission angle of the main lobe is also fixed. If the eavesdropper and the target user are at the same angular direction, the eavesdropper will be directly within the coverage area of ​​the main lobe, and the signal-to-noise ratio of the intercepted signal will exceed that of the target user, completely rendering the system's physical layer security transmission performance ineffective. Summary of the Invention

[0005] The purpose of this invention is to provide a physical layer secure transmission system and method based on a multi-frequency phased array rotating beam, overcoming the eavesdropping vulnerability caused by the fixed main lobe in traditional directional beamforming technology. Beam rotation is achieved through the frequency degrees of freedom of the multi-frequency phased array, and sidelobe randomization is achieved by combining phase degrees of freedom, thus constructing a triple security mechanism of rotating beam, zero sidelobe pointing, and sidelobe randomization. Adaptive control algorithms are designed for different eavesdropping scenarios.

[0006] To achieve the above objectives, the present invention provides a rotating beam physical layer secure transmission system based on a multi-frequency phased array, the system comprising: The baseband modulation module is used to output a carrier frequency of The modulated signal; Random inverted phased array module, composed of The antennas are arranged in a linear, uniform array with equal spacing, and the distance between adjacent antennas is [missing information]. , The maximum wavelength in a multi-frequency antenna array. The value is a positive integer. Each branch of the antenna array is equipped with a fast electronic switch to control the random reversal of the phase of the antenna array branch. The frequency converter module is used to output frequency increment signals. The frequency conversion module includes a low-frequency oscillator and a frequency multiplier, and the low-frequency oscillator outputs a frequency signal. The frequency multiplier outputs the frequency increment signal for each branch of the antenna array. , ; The modulation signal output by the baseband modulation module and the frequency increment signal output by the frequency conversion module After mixing, the generated frequency is The signal input is sent to each branch of the antenna array, and the frequency signal is controlled by the signal input. To achieve beam rotation around the target user, beam sidelobe randomization is achieved through random phase reversal control of a fast electronic switch.

[0007] Compared with existing technologies, the rotating beam physical layer secure transmission system based on a multi-frequency phased array provided by this invention has the following advantages: This system, through the collaborative design of a baseband modulation module, a random anti-phase phased array module, and a frequency conversion module, breaks through the vulnerability of same-angle eavesdropping caused by the fixed main lobe direction in traditional directional beamforming technology, and utilizes the frequency increment signal output by the frequency conversion module. Mixed with the baseband modulation signal, the frequency offset increment of the low-frequency oscillator output is precisely controlled. This allows the transmitted beam to dynamically rotate around the target user. Even if the eavesdropper and the target user are in the same location, the beam rotation can avoid the eavesdropping path, completely blocking the eavesdropper's interception of the main lobe signal. Simultaneously, the random phase-inverting phased array module utilizes the random phase-inverting control of fast electronic switches, combined with the layout design of an equally spaced linear uniform array (adjacent antenna spacing...). This allows for the randomization of beam sidelobe signals, effectively suppressing the risk of sidelobe leakage signals being intercepted and decrypted by ultra-high receiving gain eavesdropping devices, thus forming a dual security protection of beam rotation to prevent main lobe eavesdropping and sidelobe randomization to prevent leakage eavesdropping.

[0008] This invention also provides a method for secure physical layer transmission of rotating beams based on a multi-frequency phased array, the method comprising the following steps: Step S1: Initialize system parameters, including multi-frequency antenna array parameters. carrier frequency Antenna spacing Target user location Location of the eavesdropper Frequency offset increment range and the number of symbols sent ; Step S2: Determine the location of the eavesdropper If the information is known, proceed to steps S3-S5; otherwise, proceed to steps S6-S8. Step S3: Based on the location of the eavesdropper Combined with the zero sidelobe frequency offset increment formula , ， Construct a set of zero-sidelobe frequency offset increments , To adjust the integer adjustment term for the zero sidelobe position, At the speed of light, The azimuth of the eavesdropper. The distance between the eavesdropper and the center of the antenna array. For the target user's azimuth angle, The distance between the target user and the center of the antenna array. For the number of antennas, For carrier frequency, The spacing between adjacent antennas; Step S4: From Randomly selected frequency offset increment Control the beam rotation to point the zero sidelobe at the eavesdropper's location; Step S5: Transmit a symbolic private message, and repeat steps S3-S5 until... All symbols have been sent; Step S6: Increase the frequency offset increment range Divided into equal intervals Each frequency point constitutes a frequency conversion subset. ; Step S7: From the frequency conversion subset Randomly selected frequency offset increment To achieve dynamic beam rotation, while simultaneously using non-independent and identically distributed random vectors... The phase of the antenna array branches is randomly reversed to achieve dynamic beam rotation and sidelobe randomization. Step S8: Transmit a symbolic private message, and repeat steps S6-S7 until... All symbols have been sent.

[0009] Compared with existing technologies, the rotating beam physical layer security transmission system based on a multi-frequency phased array provided by this invention has the following beneficial effects: For scenarios where the location of the eavesdropper is known, the system accurately calculates adaptation parameters using the zero-sidelobe frequency offset increment formula, constructs a set of zero-sidelobe frequencies, and randomly selects offset increments, causing the zero-sidelobe beam to be directed towards the eavesdropper, thus completely blocking its signal interception path at the physical level. This solves the core problem of traditional methods where eavesdroppers at the same angle intercept the main lobe signal. For scenarios where the location of the eavesdropper is unknown, by dividing the frequency offset increment range into frequency-converting subsets at equal intervals and combining this with antenna branch phase reversal technology using random vector control, the system achieves coordinated control of dynamic beam rotation and sidelobe randomization. This prevents potential eavesdroppers from locking onto a fixed transmission path and suppresses the risk of leaked signal decryption through sidelobe signal randomization, forming comprehensive protection.

[0010] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of secure transmission at the physical layer of a rotating beam in the prior art. Figure 2 This diagram illustrates the structure of a rotating beam physical layer secure transmission system based on a multi-frequency phased array, as provided in an embodiment of the present invention. Figure 3 This diagram illustrates the uniform linear array antenna layout and antenna branch frequency distribution provided in an embodiment of the present invention. Figure 4 (a) illustrates the embodiments provided by the present invention. Beamforming corresponding to time Array factor diagram; Figure 4 (b) illustrates the embodiments of the present invention provided. Beamforming array factor corresponding to time Schematic diagram; Figure 4 (c) illustrates the embodiments of the present invention provided. Beamforming array corresponding to time Column factor diagram; Figure 5(a) shows a schematic diagram of the rotation angle beam provided in an embodiment of the present invention; Figure 5 (b) shows a schematic diagram of a conventional beam; Figure 6 This diagram illustrates the average power of the dynamic rotating beamforming array factor provided in an embodiment of the present invention. Figure 7 This diagram illustrates the security control process of the multi-frequency array rotating beam physical layer provided in an embodiment of the present invention. Figure 8 The present invention illustrates a known eavesdropper located in an embodiment of the present invention. A schematic diagram of safe speed at any location; Figure 9 (a) shows a schematic diagram of a rotating beam with an unknown eavesdropping location provided in an embodiment of the present invention; Figure 9 (b) shows a schematic diagram of a conventional beam where the location of the eavesdropping is unknown. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] In this embodiment, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations, intended to present related concepts in a specific manner, and should not be construed as superior or more advantageous than other embodiments or designs.

[0015] Example 1 like Figure 1 As shown, if the eavesdropper and the target user are at the same angle, the eavesdropper will be directly within the coverage area of ​​the main lobe of the beam. At this time, the directional beam cannot block the signal interception, and the physical layer security transmission performance is completely ineffective.

[0016] Based on this, embodiments of the present invention provide a rotating beam physical layer secure transmission system based on a multi-frequency phased array. Figure 2 This diagram illustrates a structural schematic of a rotating beam physical layer secure transmission system based on a multi-frequency phased array, as provided in an embodiment of the present invention. Figure 2 As shown, the system includes: The baseband modulation module is used to output a carrier frequency of The modulated signal serves as the baseband carrier for signal transmission.

[0017] like Figure 3 As shown, the random inverted phased array module is composed of... The antennas are arranged in a linear, uniform array with equal spacing, and the distance between adjacent antennas is [missing information]. , The maximum wavelength in a multi-frequency antenna array. The integer is positive, and each branch of the antenna array is equipped with a fast electronic switch. It is used to control the random reversal of the phase of the antenna array branches.

[0018] The fast electronic switch is composed of non-independent but identically distributed random vectors. Control, the random vector Output random variables Control fast electronic switch ,when When, the fast electronic switch selects the phase shifter output signal; when At that time, the fast electronic switch selects the phase shifter output and then inverts the signal. The antenna array's... Randomly select from the root antennas The root is used to transmit uninverted signals, the remainder The root is used to transmit an inverted signal, a random vector. The distribution satisfies: The probability is , The probability is ,in .

[0019] The frequency converter module is used to output frequency increment signals. The frequency conversion module includes a low-frequency oscillator and a frequency multiplier, and the low-frequency oscillator outputs a frequency signal. The frequency multiplier outputs the frequency increment signal for each branch of the antenna array. , .

[0020] The modulation signal output by the baseband modulation module and the frequency increment signal output by the frequency conversion module After mixing, the generated frequency is The signal input is sent to each branch of the antenna array, and the frequency signal is controlled by the signal input. To achieve beam rotation around the target user and prevent weak signals leaked from sidelobes from being intercepted and decrypted by eavesdropping devices with ultra-high receiving gain, randomized sidelobe randomization technology is employed to control the beam sidelobes. For example... Figure 2As shown, non-independent but identically distributed random vectors Output random variables Control fast electronic switch , This controls the random reversal of the phase of the antenna array branches.

[0021] Compared with existing technologies, the rotating beam physical layer secure transmission system based on a multi-frequency phased array provided by this invention has the following advantages: This system, through the collaborative design of a baseband modulation module, a random anti-phase phased array module, and a frequency conversion module, breaks through the vulnerability of same-angle eavesdropping caused by the fixed main lobe direction in traditional directional beamforming technology, and utilizes the frequency increment signal output by the frequency conversion module. Mixed with the baseband modulation signal, the frequency offset increment of the low-frequency oscillator output is precisely controlled. This allows the transmitted beam to dynamically rotate around the target user. Even if the eavesdropper and the target user are in the same location, the beam rotation can avoid the eavesdropping path, completely blocking the eavesdropper's interception of the main lobe signal. Simultaneously, the random phase-inverting phased array module utilizes the random phase-inverting control of fast electronic switches, combined with the layout design of an equally spaced linear uniform array (adjacent antenna spacing...). This allows for the randomization of beam sidelobe signals, effectively suppressing the risk of sidelobe leakage signals being intercepted and decrypted by ultra-high receiving gain eavesdropping devices, thus forming a dual security protection of beam rotation to prevent main lobe eavesdropping and sidelobe randomization to prevent leakage eavesdropping.

[0022] This invention also provides a method for secure physical layer transmission of rotating beams based on a multi-frequency phased array, the method comprising the following steps: Step S1: Initialize system parameters, including multi-frequency antenna array parameters. carrier frequency Antenna spacing Target user location Location of the eavesdropper Frequency offset increment range and the number of symbols sent ; Step S2: Determine the location of the eavesdropper If the information is known, proceed to steps S3-S5; otherwise, proceed to steps S6-S8. Step S3: Based on the location of the eavesdropper Combined with the zero sidelobe frequency offset increment formula , ， Construct a set of zero-sidelobe frequency offset increments , To adjust the integer adjustment term for the zero sidelobe position, At the speed of light, The azimuth of the eavesdropper. The distance between the eavesdropper and the center of the antenna array. For the target user's azimuth angle, The distance between the target user and the center of the antenna array. For the number of antennas, For carrier frequency, The spacing between adjacent antennas; Step S4: From Randomly selected frequency offset increment Control the beam rotation to point the zero sidelobe at the eavesdropper's location; Step S5: Transmit a symbolic private message, and repeat steps S3-S5 until... All symbols have been sent; Step S6: Increase the frequency offset increment range Divide the frequency into several frequency points at equal intervals to form a frequency conversion subset. ; Step S7: From the frequency conversion subset Randomly selected frequency offset increment To achieve dynamic beam rotation, while simultaneously using non-independent and identically distributed random vectors... The phase of the antenna array branches is randomly reversed to achieve dynamic beam rotation and sidelobe randomization. Step S8: Transmit a symbolic private message, and repeat steps S6-S7 until... All symbols have been sent.

[0023] Example 2 I. Rotating Beam Technology Figure 2 In the antenna array, the frequency deviation between adjacent branches This is called the frequency offset increment, denoted as... , . No. The frequency of each branch is represented as: (1) In formula (1) For carrier frequency, frequency offset increment .

[0024] Assumption For the far-field position away from the center of the antenna array, then from Root antenna to far-field position The propagation distance can be expressed as: (2) Then the receiver receives the first Phase difference between the antenna's transmitted signal and the array center position Represented as: (3) In millimeter-wave channels, the signal along the direct path is very strong, while the signal along the reflected path is very weak; the influence of the reflected path signal can be ignored. Amplitude is not considered. Antenna channel vector This is represented by formula (4): (4) any position The received signal is represented as: (5) In the formula, , , These represent transmit power, path loss, and receiver power factor, respectively. For beamforming array factor, For beam steering factor, As the normalization factor, The mean is 0 and the variance is Additive white Gaussian noise. The beamforming array factor is expressed as: (6) , , , , , , Corresponding beamforming array factor The waveform is as follows Figure 4 As shown in (a), 4(b), and 4(c), the beam follows... The numerical value changes as it rotates around the target position.

[0025] (1) Rotation angle control.

[0026] like Figure 5 As shown in (a)-5(b), in The coordinate plane, with ( (The origin is given, and the beam rotation angle is given.) With frequency offset increment The relationship is: (7) in, The center line of the main lobe of the beam and The included angle of the axis.

[0027] like Figure 5As shown in (a), a small frequency offset increment is added. Afterwards, The directional beam main lobe orbits the target receiving position in the coordinate plane. Rotation. When hour, =0, the beam degenerates into a traditional directional beam; when hour, The beam rotates to The first and third quadrants of the plane; when hour, The beam rotates to The second and fourth quadrants of the plane.

[0028] This simultaneously generates periodic grating lobes. The distance between the main lobe and the nearest grating lobe is: (8) (2) Beam zero sidelobe.

[0029] exist( The frequency offset increment expression corresponding to the zero sidelobe of the received beam at the receiving position is: , , (9) In the formula, Integer but Not for the number of antennas Integer multiples of.

[0030] (3) Periodicity of rotating beam array factor.

[0031] Beamforming array factor When the transmission path direction is a periodic function, it can be represented as: (10) in It is an integer.

[0032] when hour, The main lobe of the beam is along the target angle direction. Transmission, distance between the main lobe and the grating lobe The rotating beam degenerates into a traditional directional beam.

[0033] (4) Beam dynamic rotation technology.

[0034] Assumption ,exist[ Within the frequency range, equally spaced into Each frequency point constitutes a frequency conversion subset. ,and Then all frequency points Under equal probability random control, the mean power coefficient of the beamforming array factor is obtained as follows: (11) when , hour, .

[0035] if Then the mean power of the beamforming array factor converges as follows: (12) like Figure 6 As shown, Figure 6 for GHz, , rice, , , KHz, A schematic diagram of the average power factor of a dynamic rotating beamforming array at kHz.

[0036] When dynamic beam rotation control is used, the signal-to-noise ratio at the target receiving position is expressed as: (13) The signal-to-interference-plus-noise ratio at the sidelobe position is expressed as: (14) In the formula, The signal-to-noise ratio of the eavesdropper is given without considering the effect of the transmitted beamforming factor.

[0037] When the beam rotates dynamically, the system's safe rate is expressed as: (14) II. Subset modulation technique for inverted phase antennas controlled by non-independent but identically distributed random variables.

[0038] Figure 2 In the middle, when At that time, switch Output phased array The phase shifter output signal of each branch is then inverted. Therefore, At that time, the phased array's first The input phase of the power amplifier is Beam steering factor The Factors Represented as (15) In equation (15), . We can obtain . Let be a random variable, represented as (16) As can be seen, the switch According to probability Select the phase shifter output and then invert the signal, based on probability. Select the phase shifter output signal. indivual Together they form a switch control vector , Normalization factor .

[0039] Assume that of the N antennas in an antenna array, M antennas are randomly selected to transmit signals without inverters; the remaining NM antennas are used to transmit signals after inverters. Then the switching control vector... medium elements It is an identically distributed random variable, as shown in equation (17). , (17) variable Math final exam ,variance .

[0040] For the amplitude weights of any two different branches of the antenna array and , The probability of the product taking a value can be shown by equation (18). (18) Then mathematical expectation Explain the random variable and It is not independent. Switch control vector. Includes A non-independent but distributed Bernoulli random variable.

[0041] The gain of the multi-frequency array is randomly reversed using non-independent but identically distributed random variables, and the mean of the beamforming array factor is: (19) variance: (20) when , hour, .

[0042] At this point, the artificial noise power on the sidelobe is: (twenty one) The signal-to-interference-plus-noise ratio at the sidelobe position is expressed as: . (twenty two) The safe rate expression is: (twenty three) III. Rotating Beam Physical Layer Security Control Technology.

[0043] To maximize the secure rate for the target user, the transmitter expands the frequency and phase degrees of freedom of the multi-frequency phased array, employing beam rotation and beam sidelobe randomization techniques for physical layer secure communication. Furthermore, different frequency offset incremental control methods are adopted based on whether the eavesdropping location information has been accurately determined.

[0044] The specific beam steering design control process is as follows: Figure 7 As shown, the system selects different countermeasures based on whether the eavesdropping location information is known. If the eavesdropping location information is known, a set of frequency offset increments with zero sidelobes is constructed. Then, the zero sidelobes are controlled to point towards the eavesdropper with known location information. The frequency offset increments are switched at a certain rate to dynamically rotate the beam. If the eavesdropping location information is unknown, a set of zero sidelobe frequency offset increments is constructed based on the variation range and minimum interval of the frequency offset increments. The frequency offset increments and the inverted phase subset are updated at a certain rate to achieve dynamic beam rotation and randomized control of the sidelobes.

[0045] (1) The location information of the eavesdropper is known.

[0046] The location of the eavesdropper is known. Under these conditions, beam rotation can be controlled by frequency offset increments to point the zero sidelobes towards the eavesdropper, placing the eavesdropper in the zero sidelobe region and preventing signal interception. The beam rotation control algorithm is shown in Algorithm 1.

[0047] Algorithm 1 Explanation: The first line initializes the parameters for the multi-frequency antenna array, its location, and the number of generated symbols. The second line controls the sending of characters one by one; Third row: Update the zero sidelobe frequency offset vector data according to the formula; Fourth line: Randomly select a frequency offset; Fifth line: Control beam rotation to point zero sidelobes at the eavesdropping user; Line 6: A message indicating the occurrence of a symbol; Line 7: Determine if all symbols have been sent. If not, start the next loop from line 2.

[0048] Figure 8 In the middle, assuming the eavesdropper is located Eavesdropping can be carried out from any position in the beam. When the eavesdropping angle coincides with the target angle, both the eavesdropper and the target user are simultaneously on the main lobe of the beam. The physical layer security of traditional beams fails, and the security rate is zero. However, rotating beams can fully utilize the degrees of freedom in frequency parameters to control the main lobe of the beam to bypass known eavesdropping locations and transmit private information. It is even possible to point zero sidelobes at the eavesdropper, making it impossible for the eavesdropper to intercept the signal.

[0049] (2) The location of the eavesdropper is unknown. If there are potential eavesdroppers whose location information is unknown, beam rotation and beam sidelobe randomization techniques are used to improve the physical layer security performance of the system. Beam sidelobe randomization is an antenna subset modulation technique that randomly reverses the phase of the antenna array branches, converting the sidelobe leakage signal into artificial noise. The specific control flow is shown in Algorithm 2.

[0050] Explanation of each line's algorithm: Line 1: Initialize the antenna array for the competition. Line 2: Controls the number of transmitted symbols. Line 3: Randomly select a frequency offset increment. Line 4: Beam Rotation Control Line 5: Generates 1 The -1 vector of N Line 6: Randomly select M antenna branch numbers that need phase inversion from the 1:N sequence. Line 7: Update The value determines the phase of each branch of the multi-frequency phased array. Line 8: Update the phased array switch control vector The control switch randomly switches to achieve adjustment of the phase-reversed antenna subset. Line 9: A symbolic message is generated. Line 10: Determine if all symbols have been sent. If not, start the next loop from line 2.

[0051] Figure 9 middle, GHz, The number of antennas with reversed phase M=10, and the maximum frequency offset KHz, m， . Figure 9 (a) The safe rate generated by using rotating beams and random phase-reversal antenna subset modulation techniques, in the range of 0–1000 meters and 0– Within the range, except at the target location (500m, Except for the security rate dropping to zero in 8(b), the security rate in other spatial regions remains high, providing reliable physical layer secure transmission performance. In contrast, 8(b) employs conventional beamforming and random phase-reversal antenna subset modulation techniques to generate a security rate. Although conventional beamforming provides a high security rate in most areas, the fixed main lobe transmission path leaves gaps with low security rates, reducing the performance of physical layer secure transmission.

[0052] Compared with the prior art, the rotating beam physical layer secure transmission method based on a multi-frequency phased array provided by the embodiments of the present invention has the following beneficial effects: 1. Known eavesdropper scenario: Construct a set of zero sidelobe frequency offset increments, randomly select increments to control beam rotation, so that the zero sidelobes continuously point towards the eavesdropper, ensuring that the eavesdropper cannot intercept the signal; Unknown eavesdropper scenario: Combine dynamic beam rotation and sidelobe randomization, and frequently update the frequency offset increments and phase reversal subsets to keep the eavesdropper's signal-to-interference-plus-noise ratio at a low level, making it impossible for the eavesdropper to crack the information.

[0053] 2. Strong anti-eavesdropping capability: The beam rotates around the target user, with zero sidelobes pointing towards known eavesdroppers, and randomized sidelobes to deal with unknown eavesdroppers, completely solving the eavesdropping vulnerability of traditional directional beams with fixed main lobes.

[0054] 3. Stable communication with target users: The average power coefficient of the beamforming array factor at the target user is 1, the signal-to-noise ratio is stable, and the communication quality is not affected by beam rotation.

[0055] 4. High security rate: The signal-to-interference-plus-noise ratio of eavesdroppers is significantly reduced, and the system security rate remains high in spatial regions other than the target location, demonstrating excellent physical layer security transmission performance.

[0056] Furthermore, this invention also provides an electronic device, including a bus, a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor. The transceiver, the memory, and the processor are connected via a bus. When the computer program is executed by the processor, it implements the various processes of the above-described embodiment of a rotating beam physical layer secure transmission method based on a multi-frequency phased array, and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0057] Furthermore, this embodiment of the invention also provides a computer-readable storage medium storing a computer program thereon. When the computer program is executed by a processor, it implements the various processes of the above-described embodiment of a rotating beam physical layer secure transmission method based on a multi-frequency phased array, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0058] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rotating beam physical layer secure transmission system based on a multi-frequency phased array, characterized in that, include: The baseband modulation module is used to output a carrier frequency of The modulated signal; Random inverted phased array module, composed of The antennas are arranged in a linear, uniform array with equal spacing, and the distance between adjacent antennas is [missing information]. , The maximum wavelength in a multi-frequency antenna array. The value is a positive integer. Each branch of the antenna array is equipped with a fast electronic switch to control the random reversal of the phase of the antenna array branch. The frequency converter module is used to output frequency increment signals. The frequency conversion module includes a low-frequency oscillator and a frequency multiplier, and the low-frequency oscillator outputs a frequency signal. The frequency multiplier outputs the frequency increment signal for each branch of the antenna array. , ; The modulation signal output by the baseband modulation module and the frequency increment signal output by the frequency conversion module After mixing, the generated frequency is The signal input is sent to each branch of the antenna array, and the frequency signal is controlled by the signal input. To achieve beam rotation around the target user, beam sidelobe randomization is achieved through random phase reversal control of a fast electronic switch.

2. The rotating beam physical layer secure transmission system based on a multi-frequency phased array according to claim 1, characterized in that, The fast electronic switch is composed of non-independent but identically distributed random vectors. Control, the random vector Output random variables Controlling fast electronic switches ,when When, the fast electronic switch selects the phase shifter output signal; when At that time, the fast electronic switch selects the phase shifter output signal and then reverses it.

3. A rotating beam physical layer secure transmission system based on a multi-frequency phased array according to claim 2, characterized in that, The antenna array Randomly select from the root antennas The root is used to transmit uninverted signals, the remainder The root is used to transmit an inverted signal, a random vector. The distribution satisfies: The probability is , The probability is ,in .

4. A method for secure physical layer transmission of rotating beams based on a multi-frequency phased array, characterized in that, Includes the following steps: Step S1: Initialize system parameters, including multi-frequency antenna array parameters. carrier frequency Antenna spacing Target user location Location of the eavesdropper Frequency offset increment range and the number of symbols sent ; Step S2: Determine the location of the eavesdropper If the information is known, proceed to steps S3-S5; otherwise, proceed to steps S6-S8. Step S3: Based on the location of the eavesdropper Combined with the zero sidelobe frequency offset increment formula , ， Construct a set of zero-sidelobe frequency offset increments , Integer adjustment terms for adjusting the zero sidelobe position, At the speed of light, The azimuth angle of the eavesdropper. The distance between the eavesdropper and the center of the antenna array. For the target user's azimuth angle, The distance between the target user and the center of the antenna array. For the number of antennas, For carrier frequency, The spacing between adjacent antennas; Step S4: From Randomly selected frequency offset increment Control the beam rotation to point the zero sidelobe toward the eavesdropper's location; Step S5: Transmit a symbolic private message, and repeat steps S3-S5 until... All symbols have been sent; Step S6: Increase the frequency offset increment range Divided into equal intervals Each frequency point constitutes a frequency conversion subset. ; Step S7: From the frequency conversion subset Randomly selected frequency offset increment To achieve dynamic beam rotation, while simultaneously using non-independent and identically distributed random vectors... The phase of the antenna array branches is randomly reversed to achieve dynamic beam rotation and sidelobe randomization. Step S8: Transmit a symbolic private message, and repeat steps S6-S7 until... All symbols have been sent.

5. A method for secure physical layer transmission of rotating beams based on a multi-frequency phased array according to claim 4, characterized in that, In steps S4 and S7, the beam rotation angle With frequency offset increment The relationship is: = ,in, The center line of the main lobe of the beam and The included angle of the axes, when hour, =0, the beam degenerates into a traditional directional beam; when hour, The beam rotates to The first and third quadrants of the plane; when hour, The beam rotates to The second and fourth quadrants of the plane.

6. A method for secure physical layer transmission of rotating beams based on a multi-frequency phased array according to claim 4, characterized in that, In step S7, the mean value of the beamforming array factor power coefficient satisfies: ， in, For frequency conversion subset Frequency spacing, , For the minimum frequency offset increment, when , hour, .

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