Transmit sub-aperture frequency control array MIMO radar transceiver filter system design method

Abstract

The application discloses a transmitting sub-aperture frequency control array MIMO radar transceiver filter system design method, and is specifically implemented according to the following steps: step 1, obtaining the receiving signal and SINR of the transmitting sub-aperture frequency control array MIMO radar in an interference environment; step 2, establishing a transmitting and receiving beam optimization problem; and step 3, solving the transceiver filter optimization design problem of the transmitting sub-aperture frequency control array MIMO radar. The application solves the problem that the anti-interference effect is limited due to the optimization of only the receiving filter in the prior art, and improves the output SINR level and the anti-interference effect.

Description

Technical Field

[0001] This invention belongs to the field of radar technology and relates to a design method for a transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system. Background Technology

[0002] Frequency-controlled array MIMO radar transmits signals with slight frequency offsets through different transmitting elements, combining the advantages of frequency control array and MIMO technologies to achieve two-dimensional correlation between its beam and angle and range. The transmit sub-aperture refers to dividing the transmit array of the frequency-controlled array MIMO radar into several subarrays, with each subarray transmitting mutually orthogonal signals. The expansion of degrees of freedom and the introduction of frequency offset allow transmit sub-aperture frequency-controlled array MIMO radar to solve problems that are difficult for conventional phased array radars to address.

[0003] The electromagnetic environment is becoming increasingly complex, and interference signals have a significant impact on radar systems. Therefore, it is necessary to rationally design transceiver filter systems to improve the radar system's anti-jamming and detection capabilities. Existing technologies generally focus on the design of receiver filters for conventional frequency-controlled array MIMO radars, but lack research on the joint design of transceiver filters for transmitter sub-aperture MIMO radars. Existing technologies also suffer from high computational complexity in their design methods and limited signal-to-interference-and-noise ratio (SINR) performance. Summary of the Invention

[0004] The purpose of this invention is to provide a design method for a transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system, which solves the problem in the prior art that only optimizes the receiving filter, resulting in limited anti-interference effect, and improves the output SINR level and anti-interference effect.

[0005] The technical solution adopted in this invention is a design method for a transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system, which is implemented according to the following steps:

[0006] Step 1: Obtain the received signal and SINR of the transmitting sub-aperture frequency-controlled array MIMO radar under interference environment;

[0007] Step 2: Establish the transmit / receive beam optimization problem;

[0008] Step 3: Solve the problem of optimizing the design of the transmit and receive filters for the transmitter sub-aperture frequency-controlled array MIMO radar.

[0009] The invention is further characterized by:

[0010] Step 1 is implemented in the following steps:

[0011] Step 1.1: Acquire the received target signal from the transmitting sub-aperture frequency-controlled array MIMO radar;

[0012] Based on the model of a narrowband transmit sub-aperture frequency-controlled array MIMO system, the transmit array consists of M transmit array elements, which are divided into K subarrays, each containing M... T =M-K+1 array elements, the frequency offset of the transmitting array element is Δf, the receiving array includes N receiving array elements, and the expression for the arrival time of the signal transmitted by the k-th subarray at the target position is:

[0013]

[0014] in, Let (.) represent the emission weight vector of the k-th subarray. T This indicates the transpose operation. It is the baseband signal transmitted by the k-th subarray, τ r =r / c is the time delay for the radar to reach the target. θ is the subarray emission guidance vector, and θ is the target angle.

[0015] After the received signal is processed by the matched filter in the receiving system, the signal vector form of the received target signal is expressed as follows:

[0016] y=βΘ(θ,r)u+v (2)

[0017]

[0018] A(θ, r) = diag(a s (r)⊙b(θ)) (4)

[0019] a s (r) = [1, e j2πΔfr / c ,…,e j2π(K-1)Δfr / c ] T (5)

[0020] Where b(θ) = [b1, b2, ..., b K ] T v represents a mean of 0 and a covariance matrix of . The complex Gaussian white noise vector, where β is the reflection coefficient of the target; a r (θ)=[1,e j2πdsin(θ) / λ ,…,e j2π(N-1)dsin(θ) / λ ] T To receive the guide vector, This is the transmit filter vector;

[0021] When there is a target of interest and P interfering signals in the spatial domain, the received signal vector is represented as:

[0022]

[0023] Where, β0, β p Let F represent the complex reflection coefficient of the target and the reflection coefficient of the p-th interference, respectively. The received signal is sent to the receiving filter. After processing, the filtered signal is:

[0024] x = w H y (7);

[0025] Step 1.2: Obtain the SINR output from the receiver of the transmitting sub-aperture frequency-controlled array MIMO radar after passing through the receiving filter;

[0026]

[0027]

[0028]

[0029] in,(·) H This indicates the conjugate transpose operation.

[0030] Step 2 introduces the maximum energy constraint of the subarray elements, and constructs a transmit / receive filter optimization problem based on the maximum SINR criterion:

[0031]

[0032] Among them, I K Ξ represents an identity matrix of dimension K. i κ represents a matrix where all elements except the i-th diagonal element are 1 and all other elements are 0. i This represents the power limit value of the i-th transmitting element in each subarray.

[0033] The specific steps of step 3 are as follows:

[0034] Step 3.1, Receiver filter design;

[0035] Step 3.2, Transmit Beam Design;

[0036] Step 3.3: Iteratively solve the optimization problems of the receive filter and the transmit filter.

[0037] The specific steps of step 3.1 are as follows:

[0038] With the transmit filter u fixed, equation (11) is transformed into a receive filter optimization problem:

[0039]

[0040] The optimal solution for the receiving filter is:

[0041]

[0042] The specific steps of step 3.2 are as follows:

[0043] With a fixed receiving filter w, equation (11) is transformed into a transmitting filter optimization problem:

[0044]

[0045]

[0046]

[0047] For equation (14), by introducing auxiliary variables and using a positive semidefinite relaxation algorithm, the optimization problem in equation (14) is equivalent to:

[0048]

[0049] Where α represents an auxiliary variable;

[0050] Let the parameter α = t on the left-hand side of the first constraint in equation (17), where t is a constant and related to the value of the objective function in step 3.1, then equation (17) becomes:

[0051]

[0052] The value of t in the constraint condition is determined to be the SINR value obtained after optimizing the receiving filter in this iteration. Substituting t into equation (18), equation (18) is solved using the convex optimization toolbox to obtain U. opt ;

[0053] Obtain L independent and identically distributed complex Gaussian random vectors Samples, i = 1, ..., L; these vectors need to be processed to satisfy the power limits of the transmit filter:

[0054]

[0055] Select l i The vector l that maximizes SINR in the range i = 1, ..., L is the designed transmit filter.

[0056] Step 3.3 In each iteration, the transmit filter and receive filter are fixed sequentially, and optimized respectively. The optimized SINR and the optimized solution of the transmit and receive filters are recorded in the current iteration. SINR is used as the value of the auxiliary variable t in the next iteration, and the solution of the transmit and receive filters is used as the initial solution of the next iteration. This continues until the absolute value of SINR obtained after two optimizations before and after one iteration is less than the preset iteration stopping condition, and the solution of the current transmit and receive filters is output.

[0057] The beneficial effects of this invention are: it is used for the design of the transmit and receive filter system of a transmitting sub-aperture frequency-controlled array MIMO radar; it uses a cyclic iterative algorithm to transform the transmit and receive filter design problem into two sub-problems: transmit filter optimization and receive filter optimization; it transforms the optimization problem into a convex problem by introducing auxiliary variables and a semi-positive definite relaxation method; it reduces the computational time complexity and achieves better optimization performance. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the transmitter sub-aperture frequency-controlled array MIMO radar structure based on the design method of the transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system of the present invention.

[0059] Figure 2 This is the beam pattern of the design method for the transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system of the present invention.

[0060] Figure 3 This is a graph showing the SINR variation with the number of iterations for the design method of the transmitting sub-aperture frequency-controlled array MIMO radar transceiver filter system of this invention. Detailed Implementation

[0061] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0062] The present invention provides a design method for a transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system, which is implemented according to the following steps:

[0063] Step 1: Obtain the received signal and SINR of the transmitting sub-aperture frequency-controlled array MIMO radar under interference environment;

[0064] Step 1.1: Acquire the received target signal from the transmitting sub-aperture frequency-controlled array MIMO radar;

[0065] Based on the model of a narrowband transmit sub-aperture frequency-controlled array MIMO system, the transmit array consists of M transmit array elements, which are divided into K subarrays, each containing M... T =M-K+1 array elements, the frequency offset of the transmitting array element is Δf, the receiving array includes N receiving array elements, and the expression for the arrival time of the signal transmitted by the k-th subarray at the target position is:

[0066]

[0067] in, Let (.) represent the emission weight vector of the k-th subarray. T This indicates the transpose operation. It is the baseband signal transmitted by the k-th subarray, τ r =r / c is the time delay for the radar to reach the target, where r is the distance to the target. Let θ be the subarray's emission guidance vector, and θ be the target's angle. The phase difference propagated between subarrays;

[0068] After the received signal is processed by the matched filter in the receiving system, the signal vector form of the received target signal is expressed as follows:

[0069] y=βΘ(θ,r)u+v (2)

[0070]

[0071] A(θ, r) = diag(a s (r)⊙b(θ)) (4)

[0072] a s (r) = [1, e j2πΔfr / c ,…,e j2π(K-1)Δfr / c ] T (5)

[0073] Where b(θ) = [b1, b2, ..., b K ] T v represents a mean of 0 and a covariance matrix of . The complex Gaussian white noise vector, where β is the reflection coefficient of the target; a r (θ)=[1,e j2πdsin(θ) / λ ,…,e j2π(N-1)dsin(θ) / λ ] T To receive the guide vector, This is the transmit filter vector;

[0074] When there is a target of interest and P interfering signals in the spatial domain, the received signal vector is represented as:

[0075]

[0076] Where, β0, β p Let F represent the complex reflection coefficient of the target and the reflection coefficient of the p-th interference, respectively. The received signal is sent to the receiving filter. After processing, the filtered signal is:

[0077] x = w H y (7);

[0078] Step 1.2: Obtain the SINR output from the receiver of the transmitting sub-aperture frequency-controlled array MIMO radar after passing through the receiving filter;

[0079]

[0080]

[0081]

[0082] in,(·) H This indicates the conjugate transpose operation.

[0083] Step 2: Establish the transmit / receive beam optimization problem;

[0084] By introducing the maximum energy constraint of subarray elements, a transmit / receive filter optimization problem is constructed based on the maximum SINR criterion:

[0085]

[0086] Among them, I K Ξ represents an identity matrix of dimension K. i κ represents a matrix where all elements except the i-th diagonal element are 1 and all other elements are 0. i This represents the power limit value of the i-th transmitting element in each subarray.

[0087] Step 3: Solve the problem of optimizing the design of the transmit and receive filters for the transmitter sub-aperture frequency-controlled array MIMO radar.

[0088] Step 3.1, Receiver filter design;

[0089] With the transmit filter u fixed, equation (11) is transformed into a receive filter optimization problem:

[0090]

[0091] The optimal solution for the receiving filter is:

[0092]

[0093] Step 3.2, Transmit Beam Design;

[0094] With a fixed receiving filter w, equation (11) is transformed into a transmitting filter optimization problem:

[0095]

[0096]

[0097]

[0098] For equation (14), by introducing auxiliary variables and using a positive semidefinite relaxation algorithm, the optimization problem in equation (14) is equivalent to:

[0099]

[0100] Here, α represents an auxiliary variable.

[0101] Let the parameter α = t on the left-hand side of the first constraint in equation (17), where t is a constant and related to the value of the objective function in step 3.1, then equation (17) becomes:

[0102]

[0103] The value of t in the constraint condition is determined to be the SINR value obtained after optimizing the receiving filter in this iteration. Substituting t into equation (18), equation (18) is solved using the convex optimization toolbox to obtain U. opt .

[0104] Obtain L independent and identically distributed complex Gaussian random vectors Samples, i = 1, ..., L. These vectors need to be processed to satisfy the power limits of the transmit filter:

[0105]

[0106] Select l i Let l be a vector in the range i = 1, ..., L that maximizes SINR. l is the designed transmit filter.

[0107] Step 3.3: Iteratively solve the optimization problems of the receive filter and transmit filter;

[0108] In each iteration, the transmit and receive filters are fixed sequentially, and each is optimized. The optimized SINR and the optimized solutions for the transmit and receive filters are recorded for the current iteration. The SINR is used as the value of the auxiliary variable t in the next iteration, and the solution for the transmit and receive filters is used as the initial solution for the next iteration. This continues until the absolute value of the SINR obtained after two optimizations before and after an iteration is less than the preset iteration stopping condition, and then the solution for the current transmit and receive filters is output.

[0109] Example

[0110] To demonstrate the effectiveness of the design method for the transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system provided by this invention, this embodiment conducts simulation experiments and analyses under a set scenario.

[0111] In this embodiment, the simulation experiment sets the number of array elements in the transmitter array to M = 24, and the element spacing to be a uniform linear array of half a wavelength. The transmitter array can be divided into K = 15 transmitter subarrays, with a frequency offset of Δf = 4kHz between arrays, and each subarray contains M elements. T =10 array elements. A schematic diagram of a uniform linear array structure with N=15 array elements and an element spacing of half a wavelength is shown below. Figure 1 As shown, noise power The desired target is located at (40°, 35km) with a power of 5dB. Two interfering signals are located at (40°, 10km) and (30°, 30km) with powers of 30dB and 35dB respectively. The transmit filter power limiting parameter κ... i =1, i=1,2,...,M T The termination condition parameter η = 0.01 for the iterative optimization algorithm.

[0112] The simulation experiment in this embodiment uses the method of the present invention, utilizing the positions of the target and interference signals in the simulation conditions to simulate, for example... Figure 2 The image shows a two-dimensional beamline of a transmitter sub-aperture frequency-controlled array MIMO radar. From... Figure 2 As can be seen, through the joint design of the receiving and transmitting beams of the transmit sub-aperture frequency-controlled array MIMO radar in this invention, it is able to form a range-angle two-dimensional beam. This beam forms a -319dB null at interference 1 and a -378dB null at interference 2. Simultaneously, the beam focuses energy onto the desired target location. Observation of the beam pattern shaping verifies the effectiveness of the proposed algorithm in improving SINR.

[0113] To verify the convergence of the proposed method, such as Figure 3 The figure shows the relationship between the SINR obtained by this method and the number of iterations for different K values ​​(with the number of array elements in each subarray remaining constant). From Figure 3 As can be seen, the method of the present invention has good convergence and can achieve good SINR performance with a small number of iterations.

Claims

1. A design method for a transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system, characterized in that, The specific steps are as follows: Step 1: Obtain the received signal and SINR of the transmitting sub-aperture frequency-controlled array MIMO radar under interference environment; Step 2: Establish the transmit / receive beam optimization problem; Step 3: Solve the problem of optimizing the design of the transmit and receive filters for the transmitter sub-aperture frequency-controlled array MIMO radar; Step 1 is implemented in the following steps: Step 1.1: Acquire the received target signal from the transmitting sub-aperture frequency-controlled array MIMO radar; Based on the model of a narrowband transmitter sub-aperture frequency-controlled array MIMO system, the transmitter array includes M The transmission array is divided into several elements. K Each subarray contains [number] subarrays. Each array element has a frequency offset of 1 / 2000 for transmitting elements. The receiver array includes N The receiving array element, the first k The expression for the arrival time of the signal transmitted by each subarray at the target position is: (1) in, Indicates the first k The emission weight vectors of each subarray, This indicates the transpose operation. It is the first k The baseband signal transmitted by each subarray It is the time delay of the radar reaching the target. The subarray emission guide vector, From the perspective of the goal; After the received signal is processed by the matched filter in the receiving system, the signal vector form of the received target signal is expressed as follows: (2) (3) (4) (5) in, , This indicates that the mean is 0 and the covariance matrix is... The complex Gaussian white noise vector, The reflectance coefficient of the target; To receive the guide vector, This is the transmit filter vector; When there is an interesting target in the spatial domain and P The interference signal is represented by the received signal vector as follows: (6) in, , Let the complex reflection coefficient of the target and the first reflectance be represented respectively. p The reflection coefficient of the interference sends the received signal to the receiving filter. After processing, the filtered signal is: (7)； Step 1.2: Obtain the SINR output from the receiver of the transmitting sub-aperture frequency-controlled array MIMO radar after passing through the receiving filter; (8) (9) (10) in, This represents the conjugate transpose operation; Step 2 introduces the maximum energy constraint of the subarray elements, and constructs a transmit / receive filter optimization problem based on the maximum SINR criterion: (11) in, The dimension is K The identity matrix, Indicates except the first i A matrix with 1s as diagonal elements and 0s as all other elements. Indicates the number of subarrays i Power limit value for each transmitting element.

2. The design method for a transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system according to claim 1, characterized in that, The specific steps of step 3 are as follows: Step 3.1, Receiver filter design; Step 3.2, Transmit Beam Design; Step 3.3: Iteratively solve the optimization problems of the receive filter and the transmit filter.

3. The design method for a transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system according to claim 2, characterized in that, The specific steps of step 3.1 are as follows: Fixed transmit filter Equation (11) is transformed into a receiver filter optimization problem: (12) The optimal solution for the receiving filter is: (13)。 4. The design method for a transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system according to claim 3, characterized in that, The specific steps of step 3.2 are as follows: Fixed receiver filter Equation (11) is transformed into an emission filter optimization problem: (14) (15) (16) For equation (14), by introducing auxiliary variables and using a positive semidefinite relaxation algorithm, the optimization problem in equation (14) is equivalent to: (17) in, Indicates auxiliary variables; Let the parameter on the left-hand side of the first constraint in equation (17) be... , Since is a constant and depends on the value of the objective function in step 3.1, equation (17) is transformed into: (18) Determine the constraints t The value is the SINR value obtained after optimizing the receiving filter in this iteration. t Substituting into equation (18), we use the convex optimization toolbox to solve equation (18) and obtain the following result. ; Get L 3 independent and identically distributed complex Gaussian random vectors sample, These vectors need to be processed to meet the power limits of the transmit filter: (19) choose , A vector that maximizes SINR. , This refers to the designed transmission filter.

5. The design method for a transmitter sub-aperture frequency-controlled array MIMO radar transceiver filter system according to claim 4, characterized in that, In step 3.3, during each iteration, the transmit filter and receive filter are fixed sequentially, and their designs are optimized respectively. The optimized SINR and the optimized solutions for the transmit and receive filters are recorded for the current iteration, and SINR is used as an auxiliary variable in the next iteration. The value of is used as the initial solution for the transmit and receive filter, until the absolute value of SINR obtained after two optimizations before and after an iteration is less than the preset iteration stopping condition, and the current solution of the transmit and receive filter is output.

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