A method for beam sidelobe randomization based on non-independent but identically distributed random variable model control
By controlling the antenna array using a non-independent but identically distributed Bernoulli random variable model, antenna subset modulation is achieved, which solves the problem of sidelobe leakage signals being easily eavesdropped on. This realizes the randomization of sidelobe signals and the stable transmission of main lobe signals, thereby improving the security and communication rate of the physical layer.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAOGUAN COLLEGE
- Filing Date
- 2026-03-05
- Publication Date
- 2026-06-05
AI Technical Summary
In traditional millimeter-wave beamforming technology, sidelobe leakage signals are easily analyzed by eavesdropping devices, resulting in insufficient physical layer security.
A non-independent but identically distributed Bernoulli random variable model is used to control the activation or deactivation of antennas in the antenna array, forming antenna subset modulation. The main lobe signal is kept stable by a physical layer security-guided amplitude weight normalization factor, while the side lobe signals are randomized into artificial noise.
It effectively disrupts the sidelobe signal constellation diagram, improves physical layer security and bit error rate performance, and increases the security rate.
Smart Images
Figure CN122159910A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of information security technology, specifically relating to a beam sidelobe randomization method based on a non-independent but identically distributed random variable model. Background Technology
[0002] Due to the significant path loss during millimeter wave transmission in space, beamforming technology using multi-antenna arrays is commonly employed for wireless communication. In traditional millimeter-wave beamforming technology, the amplitude of the signals transmitted by each antenna in the array is equal. For example... Figure 1 As shown, traditional beamforming, while possessing excellent directional transmission characteristics with energy concentrated on the main lobe and minimal sidelobe leakage, results in a clear signal constellation in the main lobe direction, mirroring the transmitting end. Although the amplitude of the received signal constellation in the sidelobe direction is smaller, the sidelobe leakage signal's constellation diagram shares the same shape characteristics as the main lobe signal due to the phase similarity between the sidelobe and main lobe signals. If a sensitive eavesdropping device with extremely high computing power is present at the sidelobe location, its gain can be increased to intercept the weak sidelobe signal, obtaining a clear signal constellation diagram, which can then be brute-forced using high-speed computing equipment. This poses a significant challenge to the secure transmission of private information at the physical layer. Summary of the Invention
[0003] To address the problems existing in the prior art, this invention provides a beam sidelobe randomization method based on a non-independent but identically distributed random variable model.
[0004] To achieve the above objectives, the present invention provides the following solution: A beam sidelobe randomization method based on a non-independent but identically distributed random variable model includes: Step S1: Use a non-independent but identically distributed Bernoulli random variable switching control model to control the activation or deactivation of any antenna in the beam sidelobe randomized antenna array, forming antenna subset modulation. Step S2: Use a physical layer security-oriented amplitude weight normalization factor S to ensure that the amplitude and phase of the received signal of the target user located on the main lobe of the beam remain unchanged before and after using the antenna subset modulation technique, but the signal intercepted for eavesdropping located on the sidelobe of the beam is a random signal.
[0005] Preferably, the beam sidelobe randomized antenna array structure includes: a baseband modulation module, A phased antenna array consisting of several antennas, and an antenna subset control module; wherein, the antenna subset control module consists of... A non-independent and identically distributed random variable control A fast electronic switch , N antennas are arranged in a uniform linear array and are equally spaced on the XY plane.
[0006] As a preferred option, when At that time, switch Grounding, the first phased array The input terminal is grounded, so there is no signal input. At that time, switch When the baseband signal is turned on, the phased array's first... The input terminal receives the baseband adjustment output signal and performs phase adjustment. To achieve randomness in the amplitude and phase of the beam sidelobe leakage signal, the Bernoulli random variable model shown in equation (1) is used to control the switch. Switching; (1) in, ;switch According to probability Choose grounding based on probability. Select the access base modulation signal; indivual Together they form a switch control vector , ； Suppose that of the N antennas in an antenna array, M antennas are randomly activated for signal transmission, while the remaining NM antennas are idle. Then the switching control vector... medium elements It is an identically distributed random variable, as shown in equation (2). (2) Among them, variables Mathematical expectation ,variance ; For the amplitude weights of any two different branches of the antenna array and , The probability of the product taking a value is shown in equation (3). (3) Then mathematical expectation Explain the random variable and It is not independent; switch control vector Includes A non-independent but distributed Bernoulli random variable.
[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention proposes an antenna array control technique that converts beam sidelobe leakage signals into artificial noise. A non-independent, identically distributed random variable model is used to control the activation or deactivation of any antenna in the antenna array, forming antenna subset modulation. Simultaneously, to ensure transparent transmission to the target user through antenna subset modulation, a physical layer security-oriented amplitude weight normalization factor S is employed. This ensures that the amplitude and phase of the received signal from the target user located on the main lobe of the beam remain unchanged before and after using antenna subset modulation, while the signal intercepted for eavesdropping on the beam sidelobes is a random signal. Attached Figure Description
[0008] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are 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.
[0009] Figure 1 This is a flowchart of the beam sidelobe randomization method based on a non-independent but identically distributed random variable model according to an embodiment of the present invention. Figure 2 Diagram of beamside lobe randomized antenna array structure; Figure 3 Antenna layout diagram; Figure 4 Astrological chart for target customers; Figure 5 This is a simulation graph of the bit error rate; Figure 6 This is a simulation diagram for a safe speed. Detailed Implementation
[0010] 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.
[0011] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0012] Example 1 like Figure 1 As shown, this invention provides a beam sidelobe randomization method based on a non-independent but identically distributed random variable model, comprising: Step S1: Use a non-independent but identically distributed Bernoulli random variable switching control model to control the activation or deactivation of any antenna in the beam sidelobe randomized antenna array, forming antenna subset modulation. Step S2: In order to achieve transparent transmission of the antenna subset modulation technology to the target user, an amplitude weight normalization factor S with physical layer security as the guide is adopted. This can make the amplitude and phase of the received signal of the target user located on the main lobe of the beam remain unchanged before and after the antenna subset modulation technology is used, but the signal intercepted by the eavesdropping on the sidelobe of the beam is a random signal.
[0013] As one embodiment of the present invention, such as Figure 2 As shown, the beamsidelobe randomized antenna array structure includes a traditional baseband modulation module, A phased antenna array consisting of individual antennas, and an antenna subset control module. The antenna subset control module comprises... independent and identically distributed random variables control A fast electronic switch , .like Figure 3 As shown, N antennas are arranged in a uniform linear array and are equally spaced on the XY plane. The spacing between antennas. λ is the wavelength.
[0014] As one embodiment of the present invention, the switching control model for non-independent but identically distributed Bernoulli random variables is specifically as follows: like Figure 2 As shown, when At that time, switch Grounding, the first phased array The input terminal is grounded, so there is no signal input. At that time, switch When the baseband signal is turned on, the phased array's first... The input terminal receives the baseband adjustment output signal and performs phase adjustment. To achieve randomness in the amplitude and phase of the beam sidelobe leakage signal, the Bernoulli random variable model shown in equation (1) is used to control the switch. Switching.
[0015] (1) In equation (1), As can be seen, the switch According to probability Choose grounding based on probability. Select the base modulation signal for access. indivual Together they form a switch control vector , .
[0016] Assume that of the N antennas in an antenna array, M are randomly selected for transmitting signals, while the remaining NM antennas are idle. Then the switching control vector... medium elements It is an identically distributed random variable, as shown in equation (2). (2) variable Mathematical expectation ,variance .
[0017] For the amplitude weights of any two different branches of the antenna array and , The probability of their product taking a value can be shown by equation (3). (3) Then mathematical expectation Explain the random variable and It is not independent. Switch control vector. Includes A non-independent but distributed Bernoulli random variable.
[0018] As one embodiment of the present invention, in the non-independent but identically distributed Bernoulli random variable switching control algorithm, the total number of antennas N of the antenna array, the number of antennas M to be activated, and the number of symbols I to be transmitted are input, and the antenna subset switching control vector corresponding to each symbol transmission is output. Specifically, it includes: Step 11: Control the change in the number of transmitted symbols; Step 12: Generate 1 The zero vector of N ; Step 13: Randomly select M antenna branch numbers to be enabled from the 1:N sequence; Step 14: Update Specify the antenna array switch number that needs to be enabled; Step 15: Use new Value updates require the output of the switch control vector. The control switch switches randomly. Step 16: A symbolic message is generated; Step 17: Determine if all symbols have been sent. If not, start the next loop from the second line.
[0019] As one embodiment of the present invention, step S2 includes: Step 21: Statistical Characteristics of Beam Gain In millimeter-wave channels, the signal along the direct path is very strong, while the signal along the reflected path is very weak, and the influence of the reflected path signal can be ignored. Antenna channel vector The following formula (4) is shown. (4) In equation (4), The angle at which the direct path leaves the transmitting antenna. For the distance of transmission When the path loss coefficient is constant and the transmission distance is fixed, It can be considered a constant.
[0020] Beamforming Amplitude Weighted Steering Vector , The product of the Hadak codes. Let be the normalized amplitude coefficient factor constant. Then the th Each amplitude weight is .
[0021] Assume the transmitted signal is ,and The transmission power is The transmission distance is If the receiving end uses a single antenna, then at any angle... and distance The received signal is represented as (5) In the formula, for The conjugate complex vector, The mean is 0 and the variance is Gaussian white noise. The beam gain coefficient is expressed as: (6) In the formula, .
[0022] In traditional beamforming, , It is a real number.
[0023] exist A non-independent but identically distributed random variable Under the control of the switch control vector If some elements are randomly set to 0, then the beam gain system The value of becomes (7) That is, beam gain coefficient In switch control vector The signal amplitude and phase intercepted by the eavesdropper are randomly varied under control, turning the constellation diagram into a chaotic constellation with artificial interference.
[0024] Beam gain coefficient The mathematical expectation is (8) Beam gain coefficient The variance is (9) The artificial noise power on the sidelobe can be expressed as (10) Step 22, Physical Layer Security Performance The average signal-to-interference-plus-noise ratio at the receiver is . (11) In high signal-to-noise ratio scenarios The limit of the average signal-to-interference-plus-noise ratio generated by sidelobe randomization is , (12) The secure rate of physical layer secure communication is (13) The formula for calculating the bit error rate is: (14) The simulation results of physical layer security performance are as follows: (1) Constellation diagram of the location of the side lobe eavesdropping Assuming the millimeter wave frequency is 28 GHz, the total number of antennas in the antenna array The number of antennas that are randomly turned off The transmitted information uses QPSK modulation. The target angle for beam transmission... The angle of eavesdropping reception in the side lobe direction The signal-to-noise ratio for the target user and the eavesdropper is 100.
[0025] The target users in the main lobe direction and the constellation diagram in the side lobe direction are as follows: Figure 4 As shown. In In the direction of the main lobe of the beam, the constellation map of the target user is clear, and the constellation map is distributed at four coordinate points: (1,0), (0,1), (-1,0), and (0,-1). In the sidelobe direction, when using traditional beam transmission, the constellation diagram is reduced in size but still clear, distributed on four coordinate points: (0.08,0), (0,0.08), (-0.08,0), and (0,-0.08). However, in the antenna subset modulation technique controlled by non-independent but identically distributed random variables proposed in this invention, the received sidelobe constellation diagram is disordered and randomly distributed in a circular region with a radius of less than 0.8.
[0026] like Figure 4 As shown, by using non-independent but identically distributed random variables to randomly control the shutdown of some antennas, the signal receiving constellation at the sidelobe position can be disrupted, and the sidelobe leakage signal can be transformed into artificial noise.
[0027] (2) Bit error rate simulation like Figure 5 As shown, assuming the target angle When using traditional beamforming, Within the angular range, the bit error rate caused by eavesdropping is 0. When using the beam sidelobe randomization technique proposed in this invention, The zero bit error rate within the angular range indicates that the technology proposed in this invention has a narrower angular range of leakage near the target angle, resulting in better physical layer security. Furthermore, the minimum bit error rate generated by this invention on the sidelobes far from the target angle is also significantly higher than that of traditional beamforming. When eavesdropping on the sidelobes, the bit error rate of the traditional beam is 0.19, while the bit error rate generated by the beam sidelobe randomization technology proposed in this invention is 0.51, which improves the performance by 62%.
[0028] (3) Safety rate simulation like Figure 6 As shown, the beam sidelobe randomization technique proposed in this invention has a higher security rate than that of traditional beams. At angles closer to the target... Nearby, the safe rate of traditional beamforming is 4.3 bit / s / Hz, while the safe rate using sidelobe randomization technology increases to 5.8 bit / s / Hz, representing a 22% improvement in safe rate.
[0029] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A beam sidelobe randomization method based on a non-independent but identically distributed random variable model, characterized in that, include: Step S1: Use a non-independent but identically distributed Bernoulli random variable switching control model to control the activation or deactivation of any antenna in the beam sidelobe randomized antenna array, forming antenna subset modulation. Step S2: Use a physical layer security-oriented amplitude weight normalization factor S to ensure that the amplitude and phase of the received signal of the target user located on the main lobe of the beam remain unchanged before and after using the antenna subset modulation technique, but the signal intercepted for eavesdropping located on the sidelobe of the beam is a random signal.
2. The beam sidelobe randomization method based on a non-independent but identically distributed random variable model as described in claim 1, characterized in that, The beamside lobe randomized antenna array structure includes: a baseband modulation module, A phased antenna array consisting of several antennas, and an antenna subset control module; wherein, the antenna subset control module consists of... A non-independent and identically distributed random variable control A fast electronic switch , N antennas are arranged in a uniform linear array and are equally spaced on the XY plane.
3. The beam sidelobe randomization method based on a non-independent but identically distributed random variable model as described in claim 2, characterized in that, when At that time, switch Grounding, the first phased array The input terminal is grounded, so there is no signal input. At that time, switch When the baseband signal is turned on, the phased array's first... The input terminal receives the baseband adjustment output signal and performs phase adjustment. To achieve randomness in the amplitude and phase of the beam sidelobe leakage signal, the Bernoulli random variable model shown in equation (1) is used to control the switch. Switching; （1） in, ;switch According to probability Choose grounding based on probability. Select the access base modulation signal; indivual Together they form a switch control vector , ； Suppose that of the N antennas in an antenna array, M antennas are randomly activated for signal transmission, while the remaining NM antennas are idle. Then the switching control vector... medium elements It is an identically distributed random variable, as shown in equation (2). . （2） Among them, variables Mathematical expectation ,variance ; For the amplitude weights of any two different branches of the antenna array and , The probability of the product taking a value is shown in equation (3). . (3) Then mathematical expectation Explain the random variable and It is not independent; switch control vector Includes A non-independent but distributed Bernoulli random variable.