Digital phase shifter phase parameter codebook design and parameter selection method of RIS auxiliary array radar

Abstract

The invention discloses a phase parameter codebook design and parameter selection method for a digital phase shifter of an RIS auxiliary array radar, and the method comprises the steps: equally dividing a feasible region of a detection direction into a plurality of directional grids according to a directional resolution, and determining a center direction corresponding to each directional grid; dividing all the directional grids into a plurality of angle ranges, and determining directional grids included in each angle range; setting the number of code words of the phase parameter codebook according to the number of the direction grids, and dividing the phase parameter codebook into a plurality of subsets according to the number of the divided angle ranges; respectively determining a phase parameter corresponding to each code word in each subset through the center direction of the direction grid contained in the corresponding angle range; and constructing a phase parameter codebook according to the phase parameter corresponding to each code word in all the subsets. And traversing each code word in the phase parameter codebook in sequence, and selecting two code words capable of enabling the radar receiving signal to interference plus noise ratio to be maximum from the code words as the phase parameters of the radar receiving antenna and the RIS respectively.

Description

Technical Field

[0001] The invention relates to the technical field of radio transmission systems in transmitting stations, and in particular to a phase parameter codebook design and parameter selection method for a digital phase shifter of a RIS-assisted array radar. Background Art

[0002] Reconfigurable intelligent surface (RIS) is an emerging technology that is expected to significantly improve the performance of wireless communication networks. Recently, it has also been proposed for radar target detection.

[0003] The deployment scheme for RIS-assisted array radar utilizes the combination of indirect echo and direct echo to improve the radar field of view. As long as the size of RIS is large enough and the phase parameters are reasonably selected, the path loss of the radar-RIS link can be compensated, which not only improves the detection performance of the array radar but also has excellent cost-effectiveness. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention proposes a digital phase shifter phase parameter codebook design and parameter selection method for RIS-assisted array radar, which can design a reasonable phase parameter codebook for phase parameter selection of RIS. The specific technical solution is as follows:

[0005] In a first aspect, a method for designing a phase parameter codebook of a digital phase shifter of a RIS-assisted array radar is provided. In a first implementable manner of the first aspect, the method includes:

[0006] Divide the feasible domain of the detection direction into a plurality of directional grids according to the set directional resolution, and determine the central direction corresponding to each of the directional grids;

[0007] Dividing all the directional grids into a plurality of angle ranges, and determining the directional grids included in each angle range;

[0008] The number of codewords of the phase parameter codebook is set according to the number of directional grids, and the phase parameter codebook is divided into a plurality of subsets according to the number of divided angle ranges, each subset corresponding to each angle range one by one;

[0009] Determine the phase parameter corresponding to each codeword in the subset respectively through the center direction of the direction grid included in the corresponding angle range;

[0010] A phase parameter codebook is constructed according to the phase parameters corresponding to each codeword included in all the subsets.

[0011] In combination with the first implementable manner of the first aspect, in a second implementable manner of the first aspect, the phase parameter corresponding to the codeword in the subset is determined by solving the following equation:

[0012]

[0013] in, According to the phase parameter The resulting beamforming vector, Express Perform a conjugate transpose operation, k is the number of divided subsets, D is the number of directional grids, d is the distance between adjacent antenna units or RIS elements, λ is the wavelength of the radar transmission signal, and N is the number of RIS elements.

[0014] In a second aspect, a method for selecting phase parameters of a digital phase shifter of a RIS-assisted array radar is provided. In a first implementable manner of the second aspect, the method includes:

[0015] Design a phase parameter codebook for a digital phase shifter by using the digital phase shifter phase parameter codebook design method as described in the first or second implementable manner of the first aspect;

[0016] Each codeword in the phase parameter codebook is traversed in turn, and two codewords that can maximize the radar receiving signal-to-interference-noise ratio are selected as phase parameters of the radar receiving antenna and RIS respectively.

[0017] In combination with the first implementable manner of the second aspect, in a second implementable manner of the second aspect, selecting two codewords that can maximize the radar receiving signal-to-interference-noise ratio includes:

[0018] Selecting a codeword from a phase parameter codebook as a radar phase parameter, generating a corresponding beamforming vector according to the radar phase parameter, and generating a corresponding radar signal according to the beamforming vector;

[0019] Selecting a codeword from the phase parameter codebook as a RIS phase parameter in turn, generating a corresponding beamforming vector according to the RIS phase parameter, and performing weighted post-reflection on the incident signal according to the beamforming vector;

[0020] Calculate the received signal-to-interference-and-noise ratio corresponding to each RIS phase parameter according to the corresponding reflected signal, and generate a radar received signal-to-interference-and-noise ratio data set corresponding to the radar phase parameter;

[0021] Repeat the above steps to obtain radar received signal to noise ratio data sets corresponding to different codewords, and construct a radar received signal to noise ratio sequence according to all radar received signal to noise ratio data sets;

[0022] Two code words corresponding to the maximum radar reception signal to interference and noise ratio are selected from the radar reception signal to interference and noise ratio sequence as the next signal processing time interval, and the phase parameters corresponding to the radar reception antenna and the RIS.

[0023] Beneficial effect: By adopting the phase parameter codebook design and parameter selection method of the digital phase shifter of the RIS-assisted array radar of the present invention, a phase parameter codebook characterizing the quantized phase can be designed in advance. Through the designed phase parameter codebook, a reasonable phase parameter can be selected to be fed back to the reconfigurable intelligent surface for phase modulation, thereby reducing the complexity and time overhead of phase parameter calculation while improving the radar detection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation of the present invention, the following will briefly introduce the drawings required for use in the specific implementation. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0025] Figure 1 This is a schematic diagram of the application scenario of RIS-assisted single-station array radar;

[0026] Figure 2 A flow chart of a method for designing a phase parameter codebook for a digital phase shifter of a RIS-assisted array radar provided by an embodiment of the present invention;

[0027] Figure 3 A flowchart of a method for selecting phase parameters of a digital phase shifter of a RIS-assisted array radar provided by an embodiment of the present invention;

[0028] Figure 4 A specific flow chart of selecting a phase parameter from a phase parameter codebook provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0030] RIS-assisted single-station array radar application scenarios such as Figure 1 As shown, the radar transmitter and receiver are equipped with antenna arrays with equidistant linear structures. The radar transmitter transmits N orthogonal radar waveforms with equal power, that is, each transmitting antenna transmits a waveform that is orthogonal to each other. The elements of RIS are arranged in an equidistant linear structure, and the number of elements is the same as the number of antenna elements in the radar receiving antenna array, which is also N. A feedback link is provided between the array radar signal processor and the RIS controller for transmitting phase parameter codewords to the RIS.

[0031] By performing phase-weighted post-reflection on the incident signal with the help of RIS, a direct path H can be detected from the radar transmitter to the target. FM and the indirect path H of the radar transmitter -RIS- to detect the target FR H RM The target is illuminated, and the echo signal generated by the target can be detected through the direct path H between the target and the radar receiver MS and the indirect path H of detecting target-RIS-radar receiver MR H RS Observe the target.

[0032] In the local coordinate system, the positions of the array radar, RIS and the detected target are (b x , b y )、(r x , r y ) and (m x , m y ), once the system is deployed and installed, the location of the array radar and RIS (b x , b y ) and (r x , r y ) is known and fixed, and the detection target position (m x , m y ) and direction α are unknown.

[0033] like Figure 2 The flowchart of the phase parameter codebook design method of the digital phase shifter of the RIS-assisted array radar shown in the figure includes:

[0034] Step 1: divide the feasible domain of the detection direction into a plurality of directional grids according to the set directional resolution, and determine the central direction corresponding to each of the directional grids;

[0035] Step 2: Divide all the directional grids into multiple angle ranges, and determine the directional grids included in each angle range;

[0036] Step 3: setting the number of codewords of the phase parameter codebook according to the number of directional grids, and dividing the phase parameter codebook into multiple subsets according to the number of divided angle ranges, each subset corresponding to each angle range one by one;

[0037] Step 4: Determine the phase parameter corresponding to each codeword in the subset respectively through the center direction of the direction grid included in the corresponding angle range;

[0038] Step 5: construct a phase parameter codebook according to the phase parameters corresponding to each codeword included in all the subsets.

[0039] Specifically, first, the directional resolution δ can be set as needed to divide the feasible domain θ∈[0,π] of the detection direction into D=2 S Directional grid Ω={△θ 1 ,…,△θ D}.

[0040] Among them, △θ i =i×δ, S=log 2 (π / δ), then the center direction of each direction grid is:

[0041]

[0042] Then, all directions can be divided into 2 S-1 =D / 2 angle range Θ = {Θ 1 ,…Θ D2}, each angle range Θ l , l = 1, ..., D / 2 can contain two directional grids, denoted as Θl = {△θl, 1 , △θl, 2}, the central directions corresponding to these two directional grids are Il={θl, 1 ,θl, 2}.

[0043] And, {△θ l , 1 , △θ l , 2}={△θ 2(l-1) , △θ 2l};{θ l , 1 ,θ l , 2}={θ 2(l-1) ,θ 2l}.

[0044] Afterwards, a phase parameter codebook can be constructed according to the number of divided directional grids. The phase parameter codebook includes D codewords, each of which corresponds to a phase parameter Recorded as Then divide the phase parameter codebook into 2 S-1 subsets, denoted as Φ={Φ 1 ,…Φ k}, k = 1, ..., D / 2, each subset can include 2 code words, denoted as in,

[0045] Then, the phase parameter corresponding to each codeword in the subset may be determined respectively according to the central direction of the direction grid included in the corresponding angle range.

[0046] Specifically, the phase parameter corresponding to the codeword in the subset may be determined by solving the following equation:

[0047]

[0048] in, According to the phase parameter The resulting beamforming vector, Express Perform a conjugate transpose operation.

[0049]

[0050] Where k is the number of divided subsets, D is the number of directional grids, d is the distance between adjacent antenna units or RIS elements, λ is the wavelength of the radar transmission signal, and N is the number of RIS elements.

[0051] Finally, according to the phase parameters corresponding to all the codewords obtained, A digital phase shifter phase parameter codebook is rationally constructed so that reasonable phase parameters can be subsequently selected and fed back to the reconfigurable smart surface for phase modulation.

[0052] like Figure 3 The flowchart of the method for selecting phase parameters of a digital phase shifter of the RIS-assisted array radar shown in the figure comprises:

[0053] Step S1, using the above-mentioned digital phase shifter phase parameter codebook design method to design a phase parameter codebook for a digital phase shifter;

[0054] Step S2, traverse each codeword in the phase parameter codebook in turn, and select two codewords that can maximize the radar receiving signal to interference noise ratio as phase parameters of the radar receiving antenna and RIS respectively.

[0055] Specifically, first, the above-mentioned digital phase shifter phase parameter codebook design method can be used to design a phase parameter codebook for a digital phase shifter, and the specific steps are not repeated here. Then, each codeword in the phase parameter codebook can be traversed in turn, and two codewords that can maximize the radar receiving signal-to-interference-noise ratio are selected as the phase parameters of the radar receiving antenna and RIS respectively. Thereby, the complexity and time overhead of the phase parameter calculation are reduced, and the radar detection performance is improved.

[0056] In this embodiment, optionally, in step S2, two codewords that can maximize the radar receiving signal-to-interference-noise ratio are selected, including:

[0057] Step S2-1, selecting a codeword from a phase parameter codebook as a radar phase parameter, generating a corresponding beamforming vector according to the radar phase parameter, and generating a corresponding radar signal according to the beamforming vector;

[0058] Step S2-2, selecting a codeword from the phase parameter codebook as a RIS phase parameter in turn, generating a corresponding beamforming vector according to the RIS phase parameter, and performing weighted post-reflection on the incident signal according to the beamforming vector;

[0059] Step S2-3, calculating the received signal-to-interference-and-noise ratio corresponding to each RIS phase parameter according to the corresponding reflected signal, and generating a radar received signal-to-interference-and-noise ratio data set corresponding to the radar phase parameter;

[0060] Step S2-4, repeat the above steps to obtain radar received signal to interference and noise ratio data sets corresponding to different codewords, and construct a radar received signal to interference and noise ratio sequence according to all radar received signal to interference and noise ratio data sets;

[0061] Step S2-5: Select two codewords corresponding to the maximum radar reception signal to interference and noise ratio from the radar reception signal to interference and noise ratio sequence as the next signal processing time interval, and the phase parameters corresponding to the radar reception antenna and the RIS.

[0062] Specifically, first, the array radar signal processor sequentially reads from the phase parameter codebook Select a codeword And the code word The corresponding phase parameters are used as radar phase parameters to generate beamforming vectors corresponding to the radar receiving antenna array, so as to perform digital beamforming on the array receiving signal vector.

[0063] The array radar signal processor can then continue to extract the phase parameter codebook Select the codewords in turn The phase parameter corresponding to the selected codeword is used as the RIS phase parameter and transmitted to the RIS controller through the feedback link. The RIS controller generates the corresponding RIS beamforming vector according to the RIS phase parameter corresponding to the codeword and performs phase weighted post-reflection on the incident signal.

[0064] Afterwards, the array radar signal processor can measure the radar receiving signal-to-interference-noise ratio according to each reflected signal received in sequence, thereby obtaining the radar receiving signal-to-interference-noise ratio γ corresponding to different RIS phase parameters. 1 , n , n = 1, ... D. And according to the radar received signal interference noise ratio corresponding to all RIS phase parameters, a radar received signal interference noise ratio data set γ corresponding to the radar phase parameter is constructed m , n , m=2,…D.

[0065] Then, repeat the above steps to obtain the radar received signal interference and noise ratio data set corresponding to all codewords in the phase parameter codebook, and construct the radar received signal interference and noise ratio sequence {γ 1 , 1 ,…γ 1 , D , γ 2 , 1 ,…γ 2 , D ,…γ D , 1 ,…γ D , D}.

[0066] Finally, all radar received signal-to-interference-and-noise ratio values ​​in the constructed radar received signal-to-interference-and-noise ratio sequence are compared, and the largest radar received signal-to-interference-and-noise ratio value is selected:

[0067]

[0068] Finally, the maximum radar receiving signal-to-interference-noise ratio (m * , n * ) and the RIS phase parameters corresponding to the next signal processing time interval are used as the phase parameters corresponding to the radar receiving antenna and the RIS, and the beamforming vector of the radar receiving antenna array and the beamforming vector of the RIS are generated respectively. In this way, the computational complexity is low, and the computational resource configuration requirements of the array radar signal processor are low. While reducing the complexity and time overhead of the phase parameter calculation, the radar detection performance is improved.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for designing a phase parameter codebook of a digital phase shifter of a RIS-assisted array radar, characterized in that: include: Divide the feasible domain of the detection direction into a plurality of directional grids according to the set directional resolution, and determine the central direction corresponding to each of the directional grids; Dividing all the directional grids into a plurality of angle ranges, and determining the directional grids included in each angle range; The number of codewords of the phase parameter codebook is set according to the number of directional grids, and the phase parameter codebook is divided into a plurality of subsets according to the number of divided angle ranges, each subset corresponding to each angle range one by one; Determine the phase parameter corresponding to each codeword in the subset respectively through the center direction of the direction grid included in the corresponding angle range; A phase parameter codebook is constructed according to the phase parameters corresponding to each codeword included in all the subsets.

2. The digital phase shifter phase parameter codebook design method of the RIS-assisted array radar according to claim 1 is characterized in that: The phase parameters corresponding to the codewords in the subset are determined by solving the following equation: in, According to the phase parameter The resulting beamforming vector, Express Perform a conjugate transpose operation, k is the number of divided subsets, D is the number of directional grids, d is the distance between adjacent antenna units or RIS elements, λ is the wavelength of the radar transmission signal, and N is the number of RIS elements.

3. A method for selecting phase parameters of a digital phase shifter of a RIS-assisted array radar, characterized in that: include: Using the digital phase shifter phase parameter codebook design method as claimed in claim 1 or 2, a phase parameter codebook of the digital phase shifter is designed; Each codeword in the phase parameter codebook is traversed in turn, and two codewords that can maximize the radar receiving signal-to-interference-noise ratio are selected as phase parameters of the radar receiving antenna and RIS respectively.

4. The method for selecting phase parameters of a digital phase shifter of a RIS-assisted array radar according to claim 3, characterized in that: Select two codewords that can maximize the radar receiving signal-to-interference-to-noise ratio, including: Selecting a codeword from a phase parameter codebook as a radar phase parameter, generating a corresponding beamforming vector according to the radar phase parameter, and generating a corresponding radar signal according to the beamforming vector; Selecting a codeword from the phase parameter codebook as a RIS phase parameter in turn, generating a corresponding beamforming vector according to the RIS phase parameter, and performing weighted post-reflection on the incident signal according to the beamforming vector; Calculate the received signal-to-interference-and-noise ratio corresponding to each RIS phase parameter according to the corresponding reflected signal, and generate a radar received signal-to-interference-and-noise ratio data set corresponding to the radar phase parameter; Repeat the above steps to obtain radar received signal to noise ratio data sets corresponding to different codewords, and construct a radar received signal to noise ratio sequence according to all radar received signal to noise ratio data sets; Two code words corresponding to the maximum radar reception signal to interference and noise ratio are selected from the radar reception signal to interference and noise ratio sequence as the next signal processing time interval, and the phase parameters corresponding to the radar reception antenna and the RIS.

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