Virtual discrete array element hole filling sparse MIMO radar design method

Abstract

The invention discloses a sparse MIMO radar design method for filling virtual discrete array element holes, and the method comprises the steps: selecting a co-prime array or an improved co-prime array as a transmitting array, and enabling a difference common array of the co-prime array or the improved co-prime array to serve as a main array; randomly selecting a sparse array with a non-hole-difference common array as a receiving array, and taking the non-hole-difference common array as a copy translation array; the copy translation array is used for conducting periodic copy and translation operation on the main array, the copy frequency is equal to the total number of virtual array elements in the copy translation array, the translation operation of each period is completed on the positive half axis of a coordinate axis, and the copied main array in each period conducts periodic backward translation according to the interval of the virtual array elements of the copy translation array; filling the holes in the main array of the next period by using the virtual discrete array elements in the main array of the previous period; after copying and translation operations are completed, a sum-difference common array without holes in the center is constructed; the method has the advantages that the uniform degree of freedom of the MIMO radar can be fundamentally improved, and excellent performance is shown in a strong mutual coupling environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar, and relates to a design method for a MIMO radar, in particular to a design method for a sparse MIMO (Multiple-Input Multiple-Output) radar with virtual discrete element hole filling. Background Art

[0002] In recent years, MIMO radar has shown great advantages in significantly improving positioning accuracy and resolution due to its high degrees of freedom, and thus has received wide attention. However, the inherent complexity of MIMO radar has limited its practical application to a certain extent. With the rapid development of sparse array technology, applying it to MIMO radar has become an effective way to improve system performance. Currently, the design of traditional sparse MIMO arrays is mainly based on the design concept of sum co-array. However, with the continuous evolution of sparse array technology, the design strategy of sparse MIMO arrays has also undergone significant changes, and more and more research has begun to focus on the method based on sum-difference co-array to carry out the structured design of sparse MIMO arrays.

[0003] Currently, most traditional MIMO radar design methods only rely on the virtual continuous elements in the array difference co-array to fill the holes, which has obvious limitations in improving the uniform degrees of freedom (uDOF) of MIMO radar and fails to fully explore the potential of virtual discrete elements. Therefore, deeply exploring the structural relationship between virtual discrete elements and holes in the array difference co-array is of great significance for fundamentally improving the uniform degrees of freedom and then enhancing the overall performance of the MIMO radar system. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a design method for a sparse MIMO radar with virtual discrete element hole filling, which can fundamentally improve the uniform degrees of freedom of MIMO radar and shows excellent performance in a strong mutual coupling environment.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows: A design method for a sparse MIMO radar with virtual discrete element hole filling, characterized by including the following steps:

[0006] Step 1: Set the unit length between elements in the transmitting array and the receiving array of the sparse MIMO radar to be d, and d satisfies where λ represents the wavelength of the incident signal incident on the transmitting array and the receiving array;

[0007] Step 2: Select a co-prime array or an improved co-prime array as the transmitting array, and use the difference co-array of the transmitting array as the main array, making the minimum virtual element spacing of the main array be 1; select a sparse array with a non-porous difference co-array as the receiving array, and use the non-porous difference co-array of the receiving array as the replicated translation array, making the virtual element spacing of the replicated translation array be B, where B = G + r, G represents the array aperture of the transmitting array, and r represents the distance between the first hole closest to the origin of the coordinate axis on the positive semi-axis of the coordinate axis and the origin of the coordinate axis;

[0008] Step 3: Based on the prior knowledge of the symmetric structure formed by the holes and some virtual discrete elements in the main array, construct the sum-difference co-array according to the main array and the replicated translation array. The specific process is as follows:

[0009] Perform periodic replication and translation operations on the main array using the replicated translation array. The number of replication times is equal to the total number of virtual elements in the replicated translation array. Each period of translation operation is completed on the positive semi-axis of the coordinate axis. The replicated main arrays in each period are periodically translated backward at intervals of B. Use the virtual discrete elements in the main array of the previous period to fill the holes in the main array of the next period to maximize the uniform degrees of freedom of the sparse MIMO radar; after the replication and translation operations are completed, a sum-difference co-array without holes in the center is constructed.

[0010] Compared with the prior art, the advantages of the present invention are as follows:

[0011] Using the co-prime array or the improved co-prime array as the transmitting array and its difference co-array as the main array, according to the symmetric structure formed by the holes and some virtual discrete elements in the main array, filling the holes in the next period with the virtual discrete elements in the previous period. Compared with filling the holes with virtual continuous elements, it fundamentally improves the uniform degrees of freedom of the sparse MIMO radar. At the same time, it reduces the mutual coupling effect of the transmitting array, thereby improving the DOA estimation performance. Description of the Drawings

[0012] Figure 1 is the overall implementation block diagram of the method of the present invention;

[0013] Figure 2 is the structure of a main array and a replicated translation array, the process of performing replication and translation operations on the main array, and the schematic diagram of the structure of the obtained sum-difference co-array;

[0014] Figure 3 is the schematic diagram of the results of the RMSE of the sparse MIMO radar varying with the signal-to-noise ratio (SNR) without mutual coupling when two different improved co-prime arrays are respectively selected as the transmitting array, its difference co-array is used as the main array, and any sparse array is selected as the receiving array and its non-porous difference co-array is used as the replicated translation array with different values of B. Detailed implementation manners

[0015] The present invention will be further described below with reference to the accompanying drawings and in combination with specific embodiments, so that those skilled in the art can implement it according to the text of the specification. The protection scope of the present invention is not limited to this specific implementation manner.

[0016] A sparse MIMO radar design method for virtual discrete element hole filling proposed by the present invention has an overall implementation block diagram as Figure 1 shown, and it includes the following steps:

[0017] Step 1: Set the unit length between elements in the transmitting array and the receiving array of the sparse MIMO radar to be d, and d satisfies where λ represents the wavelength of the incident signal incident on the transmitting array and the receiving array.

[0018] Step 2: Select a coprime array or an improved coprime array as the transmitting array, and use the difference co-array of the transmitting array as the primary array (PA), so that the minimum virtual element spacing of the primary array is 1; select a sparse array with a non-hole difference co-array as the receiving array, and use the non-hole difference co-array of the receiving array as the replicate and shift (RS) array, so that the virtual element spacing of the replicate and shift array is B, and B = G + r, where G represents the array aperture of the transmitting array, and r represents the distance between the first hole closest to the origin of the coordinate axis on the positive half-axis of the coordinate axis of the primary array and the origin of the coordinate axis.

[0019] Here, compared with nested arrays, coprime arrays (CA) and improved coprime arrays such as ECA (Extended Coprime Array, extended coprime array), kCA (k-Times Extended Co-Prime Array, k times extended co-prime array), TCA (Thinned Coprime Array, sparse coprime array) and PCA (Padded Coprime Array, filled coprime array) etc. have higher sparsity and better performance in high signal-to-noise ratio situations. Therefore, the present invention selects the difference co-array of the coprime array or the improved coprime array as the primary array; there are holes in the primary array, which is a discontinuous array; select the difference co-array of any sparse array with a non-hole difference co-array as the replicate and shift array, and there are no holes in the replicate and shift array, which is a continuous array.

[0020] Step 3: The positions of the holes in the original main array within the interval [r, G] on the positive semi-axis of the coordinate axis form a symmetric structure with the virtual discrete array elements within the interval [-G, -r] on the negative semi-axis. The two have similar structures and expressions. This symmetric structure enables the positions of the virtual discrete array elements in the main array of the next period to be complementary to the positions of the holes in the main array of the previous period. Based on the prior knowledge that the holes and some virtual discrete array elements in the main array form a symmetric structure, according to the main array and the replicated and translated array, a sum-difference co-array is constructed. The construction process of the sum-difference co-array can be regarded as a replication and translation process, and the specific process is as follows:

[0021] Use the replicated and translated array to perform periodic replication and translation operations on the main array. The number of replications is equal to the total number of virtual array elements in the replicated and translated array. Each periodic translation operation is completed on the positive semi-axis of the coordinate axis. The replicated main arrays in each period are periodically translated backward at a distance interval B. Use the virtual discrete array elements in the main array of the previous period to fill the holes in the main array of the next period to maximize the uniform degrees of freedom of the sparse MIMO radar; after the replication and translation operations are completed, a sum-difference co-array without holes in the center is constructed.

[0022] Figure 2 The structures of the replicated and translated array and the main array, the process of performing replication and translation operations on the main array, and the schematic diagram of the structure of the obtained sum-difference co-array are given. Figure 2 In it, RS refers to the replicated and translated array, and the squares represent the virtual array elements in the replicated and translated array; Period1 represents the main array replicated for the first time, Period2 represents the main array after the second replication and translation operation, Period3 represents the main array after the third replication and translation operation, and the crosses in the main array represent the holes; SDCA represents the sum-difference co-array without holes in the center.

[0023] Since the holes and some virtual discrete array elements in the main array form a symmetric structure, the holes in the next period can be filled with the virtual discrete array elements in the previous period. At this time, B > uDOF TA , which can fundamentally improve the uniform degrees of freedom of the sparse MIMO radar. Calculate the uniform degrees of freedom uDOF of the sparse MIMO radar MIMO , uDOF MIMO = B(uDOF RA - 1) + uDOF TA , where uDOF RA represents the uniform degrees of freedom of the receiving array, that is, the number of virtual continuous array elements in the replicated and translated array. Since the replicated and translated array has no holes, the number of virtual continuous array elements in the replicated and translated array is the total number of virtual array elements in the replicated and translated array. uDOF TA represents the uniform degrees of freedom of the transmitting array, that is, the number of virtual continuous array elements in the main array.

[0024] To further illustrate the feasibility and effectiveness of the method of the present invention, experiments were conducted on the method of the present invention.

[0025] Figure 3 It shows the results of the RMSE of a sparse MIMO radar varying with the signal-to-noise ratio (SNR) without mutual coupling when two different improved co-prime arrays, TCA and PCA, are respectively selected as the transmitting arrays, and their difference co-arrays are used as the main arrays, and any sparse array with a non-porous difference co-array is randomly selected as the receiving array, and its non-porous difference co-array is used as the replicated translation array, with different values of B. As can be seen from Figure 3 it, when different improved co-prime arrays are selected, the RMSE of the designed sparse MIMO radar is smaller when B = G + r, and the DOA estimation performance is higher. This is because when B = G + r, both the virtual continuous elements and the virtual discrete elements in the main array are utilized, while when B = 2r - 1, only the virtual continuous element part in the main array is used.

[0026] Table 1 gives the specific values of the virtual element spacing B = G + r of the replicated translation array and the coupling leakage M of the transmitting array when the selected co-prime array (with 14 elements) or different improved co-prime arrays (with 14 or 13 elements) are used as the transmitting arrays and their difference co-arrays are used as the main arrays. c Specific values.

[0027] Table 1 Specific values of the virtual element spacing of the replicated translation array and the coupling leakage of the transmitting array when the selected co-prime array or different improved co-prime arrays are used as the transmitting arrays and their difference co-arrays are used as the main arrays

[0028]

[0029] In Table 1, the array configuration is the array parameters of the selected co-prime array or different improved co-prime arrays; B = 2r - 1 is used for comparison. From the data listed in Table 1, it can be seen that compared with using virtual continuous elements, using virtual discrete elements to fill the holes in the virtual array can significantly increase the virtual element spacing of the replicated translation array, and the coupling leakage of the transmitting array is smaller, improving the uniform degrees of freedom and DOA estimation performance of the sparse MIMO radar.

Claims

1. A design method for sparse MIMO radar with virtual discrete array element hole filling, characterized in that Including the following steps: Step 1: Set the unit length between the elements of the transmitting array and the receiving array of the sparse MIMO radar to be d, where d satisfies where λ represents the wavelength of the incident signal incident on the transmitting array and the receiving array; Step 2: Select a co-prime array or an improved co-prime array as the transmitting array, and use the difference co-array of the transmitting array as the main array, such that the minimum virtual element spacing of the main array is 1; select a sparse array with a hole-free difference co-array as the receiving array, and use the hole-free difference co-array of the receiving array as the replicated translation array, such that the virtual element spacing of the replicated translation array is B, where B = G + r, G represents the array aperture of the transmitting array, and r represents the distance between the first hole closest to the origin of the coordinate axis on the positive half-axis of the coordinate axis and the origin of the coordinate axis; Step 3: Based on the prior knowledge of the symmetric structure formed by the holes and some virtual discrete elements in the main array, construct the sum-difference co-array according to the main array and the replicated translation array. The specific process is as follows: Perform periodic replication and translation operations on the main array using the replicated translation array. The number of replication times is equal to the total number of virtual elements in the replicated translation array. Each translation operation in each period is completed on the positive half-axis of the coordinate axis. The replicated main arrays in each period are periodically translated backward at intervals of B. Use the virtual discrete elements in the main array of the previous period to fill the holes in the main array of the next period to maximize the uniform degrees of freedom of the sparse MIMO radar; after the replication and translation operations are completed, a sum-difference co-array without holes in the center is constructed.

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