阅读说明：本技术 一种增加自由度和减少互耦的mimo阵列设计方法 (MIMO array design method for increasing freedom degree and reducing mutual coupling ) 是由 刘明鑫 王强 王思源 于 2020-06-29 设计创作，主要内容包括：本发明提供了一种增加自由度和减少互耦的MIMO阵列设计方法,包括以下步骤：利用二级超级嵌套阵列结构分别构建MIMO雷达系统的发射阵列和接收阵列；计算得到MIMO雷达系统的合阵的差分阵；计算得到多重信号分类算法(MUSIC)的功率谱,完成对增加自由度和减少互耦MIMO阵列的设计。本申请不仅对MIMO雷达发射和接受阵列中引入二级超级嵌套结构来实现减少相互耦合,还保证合阵的差分阵没有空洞具有较大自由度(DOF)的特性。其具有以下优点：1)具有封闭形式的阵元位置和无孔的合阵的差分阵。2)具有比互质阵列和线性阵列具有更高的DOF容量。3)与嵌套阵列和线性阵列相比,其相互耦合也较少。(The invention provides a MIMO array design method for increasing the degree of freedom and reducing mutual coupling, which comprises the following steps: respectively constructing a transmitting array and a receiving array of the MIMO radar system by utilizing a two-level super nested array structure; calculating to obtain a differential array of a combined array of the MIMO radar system; and calculating to obtain a power spectrum of a multi-signal classification algorithm (MUSIC), and completing the design of increasing the degree of freedom and reducing the mutual coupling MIMO array. The method not only introduces a secondary super nested structure into the MIMO radar transmitting and receiving array to reduce mutual coupling, but also ensures that no hole exists in the differential array of the array combination and has the characteristic of larger degree of freedom (DOF). It has the following advantages: 1) a differential array having closed form array element positions and a closed-pore array. 2) Have a higher DOF capacity than co-prime and linear arrays. 3) They also couple less to each other than nested and linear arrays.)

1. A method for designing a MIMO array with increased degrees of freedom and reduced mutual coupling, comprising the steps of:

s1, constructing a transmitting array of the MIMO radar system by using the super nested array structure, and constructing a receiving array of the MIMO radar system by using the super nested array structure with the array element spacing enlarged;

s2, emitting orthogonal waves, and calculating to obtain a differential array of a combined array of the MIMO radar system according to the emitting array and the receiving array;

and S3, calculating according to the combined array differential array of the MIMO radar system to obtain the power spectrum of the multi-signal classification algorithm MUSIC, and completing the design of increasing the degree of freedom and reducing the mutual coupling MIMO array.

2. The method of claim 1, wherein the differential array of the MIMO radar system in step S2 is expressed as follows:

wherein the content of the first and second substances,differential array representing a composite array of a MIMO radar system, (m)_j1-m_j2) d and (n)_i1-n_i2) Dd denotes a differential array of the transmit and receive arrays, respectively, m_j1d represents the m-th_j1Position of a transmitting array element, n_i1Dd denotes the nth_i1Position of an acceptance array element, m_j2d represents the m-th_j2Position of a transmitting array element, n_i2Dd denotes the nth_i2Position of an acceptance array element, m_j1And m_j2All represent the position coordinates of the transmitting array elements and are integers, n_i1And n_i2Each representing the position coordinates of an accepting array element and being an integer, D representing a positive integer, D representing half a wavelength of the incident signal,

3. The method of claim 1, wherein the degree of freedom of the MIMO radar system in step S2 is expressed as follows:

wherein f represents the degree of freedom of the MIMO radar system, f_MAnd f_NRepresenting degrees of freedom of the emitting array and the receiving array, respectively, M tableThe number of transmitting array elements is shown, N is the number of receiving array elements, and K is the total number of physical array elements.

Technical Field

The invention belongs to the technical field of radars, and particularly relates to a MIMO array design method for increasing the degree of freedom and reducing mutual coupling.

Background

A multiple-input multiple-output (MIMO) radar transmits a plurality of orthogonal or incoherent detection signals, and receives echo signals by using a matched filter bank at a receiving end, so that a virtual array with larger aperture and higher degree of freedom is provided for the design of a radar system and a signal processing algorithm. According to the configuration of the transmitting and receiving arrays, the MIMO radar system can be divided into a distributed MIMO radar and a co-located MIMO radar, wherein the co-located MIMO radar obtains a virtual aperture larger than an actual aperture by utilizing waveform diversity, so that the target detection and parameter identification capabilities can be improved.

In recent years, the problem of co-located MIMO radar virtual aperture has received a wide attention, such as nested arrays with closed expressions, co-prime arrays, and minimum redundant arrays. These arrays can provide a larger aperture, higher degree of freedom than uniform linear arrays by utilizing second order statistics of the received data. Even if the number of sources is larger than the number of array elements, the position of the source can be effectively detected. In view of this, the existing literature proposes a minimum redundancy MIMO array, which uses the minimum redundancy array as a transmitting and receiving array, and performs differential processing on a combined array generated by the MIMO radar to obtain virtual expansion of the number of receiving array elements, thereby greatly improving the degree of freedom of the array, but such sparse optimization of a radar array structure usually involves a large amount of computation. The existing literature proposes a co-prime MIMO array, and the minimum redundant array in the literature is replaced by a co-prime array in the design of the array, so that although the calculation amount is reduced and the degree of freedom of the array is improved, the differential array is a linear array with holes, and a spatial smoothing algorithm cannot be used for decorrelating signals and then carrying out accurate wave arrival angle (DOA) estimation. The existing literature proposes a nested MIMO array design using a nested array as a transmitting array and a receiving array, which can further improve the degree of freedom of the MIMO radar and obtain a uniform linear array without holes, but the nested array includes a dense ULA in the physical array, resulting in higher mutual coupling.

Disclosure of Invention

In view of the above-mentioned deficiencies in the prior art, the present invention provides a MIMO array design method with increased degrees of freedom and reduced mutual coupling, wherein the newly formed array has higher degree of freedom (DOF) capacity and less mutual coupling than other existing arrays with the same number of array elements.

In order to achieve the above purpose, the invention adopts the technical scheme that:

the scheme provides a MIMO array design method for increasing the degree of freedom and reducing mutual coupling, which comprises the following steps:

s1, constructing a transmitting array of the MIMO radar system by using the super nested array structure, and constructing a receiving array of the MIMO radar system by using the super nested array structure with the array element spacing enlarged;

s2, emitting orthogonal waves, and calculating to obtain a differential array of a combined array of the MIMO radar system according to the emitting array and the receiving array;

and S3, calculating according to the combined array differential array of the MIMO radar system to obtain the power spectrum of the multi-signal classification algorithm MUSIC, and completing the design of increasing the degree of freedom and reducing the mutual coupling MIMO array.

Further, the expression of the differential array of the sum array of the MIMO radar system in step S2 is as follows:

wherein the content of the first and second substances,differential array representing a composite array of a MIMO radar system, (m)_j1-m_j2) d and (n)_i1-n_i2) Dd denotes a differential array of the transmit and receive arrays, respectively, m_j1d represents the m-th_j1Position of a transmitting array element, n_i1Dd denotes the nth_i1Position of an acceptance array element, m_j2d represents the m-th_j2Position of a transmitting array element, n_i2Dd denotes the nth_i2Position of an acceptance array element, m_j1And m_j2All represent the position coordinates of the transmitting array elements and are integers, n_i1And n_i2Each representing the position coordinates of an accepting array element and being an integer, D representing a positive integer, D representing half a wavelength of the incident signal,and

respectively, an integer set, M a transmitting array element number, and N a receiving array element number.

Still further, the expression of the degrees of freedom of the MIMO radar system in step S2 is as follows:

wherein f represents the degree of freedom of the MIMO radar system, f_MAnd f_NThe degrees of freedom of the transmitting array and the receiving array are respectively expressed, M represents the number of transmitting array elements, N represents the number of receiving array elements, and K represents the total number of physical array elements.

The invention has the beneficial effects that:

(1) under the condition of fixed array quantity, the MIMO array waveform design problem exists during mutual coupling, and the application provides an optimized array arrangement mode to obtain DOF and minimum mutual coupling effect to the maximum extent. The optimal array element distribution number of the transmitting and receiving arrays is calculated for the given array element number, and the closed form expression of the physical array element position and the virtual array element position is derived by adopting super nested array arrangement. The newly formed array has a higher DOF capacity and less mutual coupling than other existing arrays having the same number of array elements.

(2) The application researches a co-located MIMO radar, solves the problem of increasing the virtual aperture in the presence of unknown array coupling, and provides a new MIMO array design method. In particular, the super-nested structure is introduced into the MIMO radar transmitting and receiving array to reduce mutual coupling. In addition, the method also provides necessary conditions for ensuring the larger DOF characteristic of the corresponding array-combined differential array. Thus, the resulting array has the following advantages: 1) the array has closed form array element position and non-hole differential array. 2) Have a higher uniform DOF capacity than co-prime arrays and uniform linear arrays. 3) They couple to each other less than nested arrays and uniform linear arrays.

Drawings

FIG. 1 is a flow chart of the method of the present invention.

Fig. 2 is a structural diagram of the MIMO array in this embodiment when K is 16.

Fig. 3 is a diagram of the degree of freedom ratio in this embodiment.

Fig. 4 is a power spectrum diagram of a uniform linear array, a co-prime array, a nested array and a multi-signal classification algorithm (MUSIC) of the proposed structure in the absence of mutual coupling in the present embodiment.

Fig. 5 is a power spectrum diagram of the multi-signal classification algorithm (MUSIC) of the uniform linear array, the co-prime array, the nested array and the proposed structure in the case of mutual coupling in this embodiment.

Detailed Description

The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.