Phase parameter codebook design and parameter selection method for digital phase shifter of RIS-assisted array radar

Abstract

The present invention discloses a digital phase shifter phase parameter codebook design and parameter selection method for a RIS-assisted array radar, comprising the following steps: dividing the feasible domain of the detection direction into multiple directional grids according to the directional resolution, and determining the center direction corresponding to each directional grid; dividing all directional grids into multiple angular ranges, and determining the directional grids contained in each angular range; setting the number of codewords in 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 angular ranges; determining the phase parameter corresponding to each codeword in each subset based on the center direction of the directional grid contained in the corresponding angular range; and constructing a phase parameter codebook based on the phase parameters corresponding to each codeword in all subsets. Each codeword in the phase parameter codebook is sequentially traversed, 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 the RIS, respectively.

Description

Technical Field

[0001] The present 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 has the potential 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 uses the combination of indirect echoes and direct echoes to improve the radar field of view. As long as the size of the RIS is large enough and the phase parameters are reasonably selected, the path loss of the radar-RIS link can be compensated. This not only improves the detection performance of the array radar, but also has excellent cost-effectiveness. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention proposes a phase parameter codebook design and parameter selection method for digital phase shifters in RIS-assisted array radars. This method can design a reasonable phase parameter codebook for phase parameter selection in RIS. The specific technical solution is as follows:

[0005] In a first aspect, a method for designing a phase parameter codebook for 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 multiple directional grids according to the set directional resolution, and determine the center 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 in the phase parameter codebook is set according to the number of directional grids, and the phase parameter codebook is divided into multiple subsets according to the number of divided angle ranges, each subset corresponding to each angle range;

[0009] Determining the phase parameter corresponding to each codeword in the subset respectively according to 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 generated beamforming vector, Express Perform the conjugate transpose operation, 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.

[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] Designing a phase parameter codebook for a digital phase shifter 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 the phase parameters of the radar receiving antenna and the RIS respectively.

[0017] In conjunction with the first implementable manner of the second aspect, in the second implementable manner of the second aspect, selecting two codewords that can maximize the radar reception signal-to-interference-and-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 sequence, 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-interference-and-noise ratio data sets corresponding to different codewords, and construct a radar received signal-to-interference-and-noise ratio sequence based on all radar received signal-to-interference-and-noise ratio data sets;

[0022] Two code words corresponding to the maximum radar receiving signal to interference and noise ratio are selected from the radar receiving signal to interference and noise ratio sequence as the next signal processing time interval, and phase parameters corresponding to the radar receiving antenna and 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 representing the quantized phase can be designed in advance. Through the designed phase parameter codebook, reasonable phase parameters can be selected and fed back to the reconfigurable intelligent surface for phase modulation, thereby reducing the complexity and time overhead of phase parameter calculation while improving radar detection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the specific embodiments. 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 flowchart of a method for designing a phase parameter codebook for a digital phase shifter of a RIS-assisted array radar according to an embodiment of the present invention;

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

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

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

[0030] RIS assisted single-station array radar application scenarios such as Figure 1 As shown in the figure, the radar transmitter and receiver are equipped with antenna arrays with an equidistant linear structure. The radar transmitter transmits N orthogonal radar waveforms of equal power, meaning each transmitting antenna transmits a waveform orthogonal to the others. The RIS elements are arranged in an equidistant linear structure, with the same number of elements as the antenna elements in the radar receiving antenna array, also N. A feedback link is provided between the array radar signal processor and the RIS controller to transmit 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 target detection-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 FIG. 1 includes:

[0034] Step 1: Divide the feasible domain of the detection direction into multiple direction grids according to the set direction resolution, and determine the center direction corresponding to each direction grid;

[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 in 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;

[0037] Step 4: Determine the phase parameter corresponding to each codeword in the subset based on 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, and the feasible domain θ∈[0,π] of the detection direction can be divided into D=2 S Directional grid Ω={△θ1,…,△θ D}.

[0040] Among them, △θ i =i×δ, S=log2(π / δ), then the center direction of each direction grid is:

[0041]

[0042] Then, all direction grids can be divided into 2 S-1 =D / 2 angle range Θ={Θ1, ...Θ D2}, each angle range Θ l , l = 1,…, D / 2 can contain two directional grids, denoted as Θl = {△θl, 1, △θl, 2}, and the central directions corresponding to these two directional grids are Il = {θl, 1, θl, 2} respectively.

[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 codeword corresponds to a phase parameter Recorded as Then divide the phase parameter codebook into 2 S-1 subsets, denoted as Φ={Φ1,…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 can be determined respectively according to the center direction of the direction grid included in the corresponding angle range.

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

[0047]

[0048] in, According to the phase parameter The generated beamforming vector, Express Performs 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 transmitted signal, and N is the number of RIS elements.

[0051] Finally, the phase parameters corresponding to all the codewords obtained can be 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 FIG. 1 includes:

[0053] Step S1: using the above-mentioned digital phase shifter phase parameter codebook design method to design a phase parameter codebook for the 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 the phase parameters of the radar receiving antenna and the RIS respectively.

[0055] Specifically, the aforementioned digital phase shifter phase parameter codebook design method can be used to design a digital phase shifter phase parameter codebook. The specific steps are not repeated here. Then, each codeword in the phase parameter codebook can be sequentially traversed, and the two codewords that maximize the radar receive signal-to-interference-and-noise ratio are selected as the phase parameters for the radar receive antenna and the RIS, respectively. This reduces the complexity and time overhead of phase parameter calculation while improving radar detection performance.

[0056] In this embodiment, optionally, in step S2, two codewords that can maximize the radar reception signal-to-interference-and-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: Select a codeword from the phase parameter codebook as a RIS phase parameter, generate a corresponding beamforming vector according to the RIS phase parameter, and perform 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 based on 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 RIS.

[0062] Specifically, first, the array radar signal processor sequentially reads the phase parameter codebook Select a codeword And the codeword 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 sequence The phase parameters corresponding to the selected codewords are used as RIS phase parameters and transmitted to the RIS controller via a feedback link. The RIS controller generates the corresponding RIS beamforming vector based on the RIS phase parameters corresponding to the codewords 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-and-noise ratio according to each reflected signal received in sequence, thereby obtaining the radar receiving signal-to-interference-and-noise ratio γ1 corresponding to different RIS phase parameters. n , n=1, ... D. And according to the radar received signal to interference and noise ratio corresponding to all RIS phase parameters, a radar received signal to interference and 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 to interference and noise ratio data set corresponding to all codewords in the phase parameter codebook, and construct the radar received signal to interference and noise ratio sequence {γ1, 1, ...γ1, D ,γ2,1,…γ2, 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 and noise ratio value (m * , n * ) and the RIS phase parameters corresponding to the next signal processing interval are used as the phase parameters corresponding to the radar receive antenna and the RIS, respectively. The beamforming vectors for the radar receive antenna array and the RIS are then generated. This approach reduces computational complexity and the computational resource requirements of the array radar signal processor. This reduces the complexity and time overhead of phase parameter calculation while improving radar detection performance.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. 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 make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions 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 description of the present invention.

Claims

1. A method for designing a phase parameter codebook for a digital phase shifter of a RIS-assisted array radar, characterized in that: include: Divide the feasible domain of the detection direction into multiple directional grids according to the set directional resolution, and determine the center 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 in the phase parameter codebook is set according to the number of directional grids, and the phase parameter codebook is divided into multiple subsets according to the number of divided angle ranges, each subset corresponding to each angle range; Determining the phase parameter corresponding to each codeword in the subset respectively according to 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 generated beamforming vector, Express Perform the conjugate transpose operation, 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.

3. A method for selecting phase parameters of a digital phase shifter of a RIS-assisted array radar, characterized in that: include: Designing a phase parameter codebook for a digital phase shifter using the method for designing a phase parameter codebook for a digital phase shifter as claimed in claim 1 or 2; 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 the phase parameters of the radar receiving antenna and the RIS respectively.

4. The method for selecting phase parameters of a digital phase shifter of a RIS-assisted array radar according to claim 3, wherein: Select two codewords that can maximize the radar receiving signal-to-interference-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 sequence, 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-interference-and-noise ratio data sets corresponding to different codewords, and construct a radar received signal-to-interference-and-noise ratio sequence based on all radar received signal-to-interference-and-noise ratio data sets; Two code words corresponding to the maximum radar receiving signal to interference and noise ratio are selected from the radar receiving signal to interference and noise ratio sequence as the next signal processing time interval, and phase parameters corresponding to the radar receiving antenna and RIS.

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