Radar communication integrated positioning method and system based on angle-time delay joint estimation

Abstract

The application discloses a radar communication integrated positioning method and system based on angle-time delay joint estimation, relates to the technical field of radar communication integration, and comprises the following steps: constructing a radar communication integrated signal, wherein the radar communication integrated signal comprises multiple pulses, and each pulse comprises multiple OFDM symbols; constructing a radar communication integrated echo receiving model, and preprocessing echo signals in the radar communication integrated echo receiving model to obtain processed echo signals; eliminating communication information in an echo signal matrix to obtain an echo signal matrix after eliminating the communication information; and estimating angle parameters and time delay parameters in sequence according to the echo signal matrix after eliminating the communication information, so as to obtain the angle parameters and the time delay parameters and realize target positioning. The application can accurately obtain position information of the target.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radar communication integration, and particularly relates to a radar communication integration positioning method and system based on joint angle-time delay estimation. BACKGROUND

[0002] With the development of information technology, multi-functional radars, intelligent vehicles, 5G large-scale antennas and other systems are becoming increasingly complex, mainly in that these systems have more and more requirements for radar detection and wireless communication functions. To realize these two functions, the traditional way is to simply place radar and communication equipment separately and make them play their respective roles, while the emergence of radar communication integration systems can manage radar and communication equipment from the aspects of resources and waveform design, realize system equipment sharing, meet the requirements of radar detection and wireless communication, and greatly reduce the weight, volume, energy consumption and complexity of the system, which is an important trend for the development of future multi-functional electronic systems.

[0003] In the prior art, in the process of realizing target positioning by using a traditional radar signal, the combination of radar and communication functions in one signal waveform to simultaneously realize target positioning and data communication functions is not considered, and the problems of large amount of calculation in traditional joint angle-time delay estimation based on OFDM signals and the influence of communication information carried by the waveform on parameter estimation are not considered, which is not conducive to accurate target positioning.

[0004] Therefore, it is urgent to improve the defects in the prior art and improve the target positioning accuracy. SUMMARY

[0005] To solve the above problems in the prior art, the application provides a radar communication integration positioning method and system based on joint angle-time delay estimation. The technical problems to be solved by the application are solved by the following technical solutions:

[0006] In a first aspect, the application provides a radar communication integration positioning method based on joint angle-time delay estimation, comprising:

[0007] constructing a radar communication integration signal, the radar communication integration signal comprising a plurality of pulses, each pulse comprising a plurality of OFDM symbols;

[0008] constructing a radar communication integration echo reception model, and preprocessing echo signals in the radar communication integration echo reception model to obtain processed echo signals;

[0009] eliminating communication information in the processed echo signals to obtain echo signals after eliminating the communication information;

[0010] According to the echo signal of the communication information, the angle parameter and the time delay parameter are estimated in sequence, and the angle parameter and the time delay parameter are obtained, so as to realize target positioning.

[0011] Optionally, the expression of the radar-communication integrated signal s(t) is:

[0012]

[0013] Wherein, N p is the number of pulses included in the radar-communication integrated signal, p is the pth pulse, N s is the number of OFDM symbols included in each pulse, s is the st OFDM symbol, N c is the number of subcarriers included in the OFDM symbol, n is the nth subcarrier, d p,s,n is the communication information carried by the nth subcarrier in the st OFDM symbol in the pth pulse, e is the exponential function with base, j is the imaginary unit, π is the circular constant, c is the speed of light, Δf is the subcarrier spacing, t is the time, T s is the length of the OFDM symbol, T p is the pulse repetition period, and rect[·] is the rectangular window function.

[0014] Optionally, the radar-communication integrated echo receiving model includes M linear array elements arranged uniformly; wherein, the echo signals arriving at different array elements correspond to different echo paths, and the time delay τ i of the echo signal propagating in the ith echo path is:

[0015]

[0016] Wherein, i is the ith echo path, i=1,2,…,L p , L p is the number of paths of the echo signals arriving at each array element, R i is the distance of the ith target.

[0017] Optionally, the Park algorithm is used to preprocess the echo signal to obtain a data processing region in the echo signal; wherein, the echo signal is the entire OFMD symbol, which includes a cyclic prefix T cp region and a data processing region.

[0018] Optionally, the process of preprocessing the echo signal using the Park algorithm to obtain the data processing region in the echo signal includes:

[0019] The Park algorithm is used to preprocess the echo signal to obtain the processed echo signal at time t , and the expression is:

[0020]

[0021] Among them, a i Let w(t) be the complex fading coefficient of the i-th echo path, and w(t) be additive complex white Gaussian noise. To transmit a signal, f c For carrier frequency;

[0022] Based on the processed echo signal at time t Acquire the echo signal received by the m-th array element

[0023] The echo signal received by the m-th array element Down-convert to baseband and remove the cyclic prefix to obtain the m-th array element, p-th pulse, and s-th OFDM symbol;

[0024] Discretize and sample the m-th array element, the p-th pulse, and the s-th OFDM symbol at a rate with a bandwidth of B;

[0025] Based on the sampling results, the echo signal r received by the m-th array element is obtained. m (s,p).

[0026] Optionally, for the echo signal r m (s,p) is used for frequency domain transformation to eliminate communication information in the echo signal.

[0027] Optionally, the process of obtaining the angle parameters includes:

[0028] Obtain the channel frequency domain response estimation vector x for the m-th array element, the p-th pulse, and the s-th OFDM symbol. m ;

[0029] The channel frequency domain response estimation vector x is based on the m-th array element, the p-th pulse, and the s-th OFDM symbol. m Along the spatial dimension, obtain the channel frequency domain response estimation vector x of M array elements;

[0030] Obtain the angle and time delay parameters in the channel frequency domain response estimation vector x of M array elements, and for the same pulse N s The covariance matrix R of the channel frequency domain response estimation vector x composed of OFDM symbols is calculated and subspace decomposition is performed.

[0031] Obtain the intermediate matrix V, and based on the intermediate matrix V, obtain the extended signal subspace U after subspace decomposition of the covariance matrix R. S ;

[0032] The extended signal subspace U obtained from the decomposition of the covariance matrix R S Obtain matrix Ψ; and obtain the angle parameters based on the eigenvalues ​​of matrix Ψ.

[0033] Optionally, the time delay parameter acquisition process comprises:

[0034] acquiring a channel frequency domain response estimation vector x of the mth array element, the pth pulse and the sth OFDM symbol m ;

[0035] acquiring a channel frequency domain response estimation vector x of the mth array element, the pth pulse and the sth OFDM symbol according to the channel frequency domain response estimation vector x of the mth array element, the pth pulse and the sth OFDM symbol m ;

[0036] acquiring angle parameters and time delay parameters in the channel frequency domain response estimation vector x of the M array elements, and performing covariance matrix operation and subspace decomposition on channel frequency domain response estimation vectors x of N s OFDM symbols of the same pulse to obtain a subspace decomposition matrix R;

[0037] acquiring a permutation matrix C, and acquiring a matrix U according to the permutation matrix C and an extended signal subspace U S in the subspace decomposition matrix R D ;

[0038] acquiring eigenvalues according to the matrix U D , and acquiring angle parameters according to the eigenvalues

[0039] In a second aspect, the application further provides a radar-communication integrated positioning system based on joint angle-time delay estimation, comprising:

[0040] a signal transmitting module configured to construct a radar-communication integrated signal, the radar-communication integrated signal comprising a plurality of pulses, each pulse comprising a plurality of OFDM symbols;

[0041] a return signal receiving module configured to construct a radar-communication integrated return signal receiving model, and to preprocess return signals in the radar-communication integrated return signal receiving model to obtain processed return signals;

[0042] a return signal processing module configured to eliminate communication information in the processed return signals to obtain return signals with eliminated communication information;

[0043] a target positioning module configured to sequentially estimate angle parameters and time delay parameters according to the return signals with eliminated communication information, to obtain the angle parameters and the time delay parameters, and to realize target positioning.

[0044] The application has the following beneficial effects: ​​

[0045] (1) The radar communication integrated positioning method and system based on angle delay joint estimation provided by the present invention can improve the data transmission rate of the signal under the same bandwidth; and the designed signal can be regarded as a time slot in the communication, which is easier to achieve synchronization compared with the traditional OFDM radar waveform.

[0046] (2) The present invention provides a radar-communication integrated positioning method and system based on angle delay joint estimation. Based on the angle delay joint estimation method, the super-resolution algorithm of subspace is used to estimate the parameters of OFDM radar-communication integrated echo signal, which can accurately obtain the target's position information.

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0048] Figure 1 This is a flowchart of a radar-communication integrated positioning method based on joint estimation of angle and time delay provided in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of an OFDM radar signal in the prior art provided by the embodiments of the present invention;

[0050] Figure 3 This is a schematic diagram of an OFDM radar-communication integrated signal provided in an embodiment of the present invention;

[0051] Figure 4 This is a schematic diagram of an OFDM radar-communication integrated echo reception model provided in an embodiment of the present invention;

[0052] Figure 5 This is a schematic diagram of the Park algorithm provided in an embodiment of the present invention;

[0053] Figure 6 This is a schematic diagram of a symbolic timing simulation of the Park algorithm provided in an embodiment of the present invention;

[0054] Figure 7 This is a schematic diagram of a scatter plot of the joint angle and time delay target estimation position provided in an embodiment of the present invention;

[0055] Figure 8 This is a schematic diagram illustrating the comparison between the angle-delay joint target estimation position and the actual position provided in an embodiment of the present invention;

[0056] Figure 9(a) is a schematic diagram of an angle parameter estimation error provided by an embodiment of the present invention;

[0057] Figure 9(b) is a schematic diagram of the time delay parameter estimation error provided in an embodiment of the present invention;

[0058] Figure 10 This is a schematic diagram illustrating the relationship between the target positioning error and the signal-to-noise ratio in the joint estimation of angle and time delay provided by an embodiment of the present invention.

[0059] Figure 11 This is a schematic diagram illustrating the relationship between the angle delay joint estimation target positioning error and the number of symbols provided in an embodiment of the present invention;

[0060] Figure 12 This is a schematic diagram of the communication bit error rate of the OFDM radar-communication integrated signal provided in an embodiment of the present invention. Detailed Implementation

[0061] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0062] Among existing technologies, OFDM has advantages such as high spectral efficiency, low sidelobes of autocorrelation function, flexible subcarrier modulation, and resistance to multipath fading. It has been widely used in communication and radar. Moreover, scholars have conducted research on the angle and time delay estimation of OFDM signals, which are mainly divided into two categories: one is to estimate the angle and time delay independently and then use a pairing algorithm to pair the estimated angle and time delay, but pairing errors may occur under low signal-to-noise ratio conditions; the other is the joint angle and time delay estimation method, which can realize automatic pairing between the two and improve the efficiency of the algorithm.

[0063] In existing scheme 1, the 2D-MUSIC algorithm is used to search for two-dimensional spectral peaks of time delay and angle, which can be paired to achieve parameter estimation of OFDM signal time delay and angle, thereby realizing target localization. However, existing scheme 1 requires a two-dimensional search, which involves a large amount of computation and is time-consuming, making it difficult to implement in engineering. In existing scheme 2, the ESPRIT algorithm is used to solve two translation-invariant equations to obtain two matrices containing angle and time delay information. Then, joint angle estimation is used to estimate the angle and time delay, thereby realizing target localization. However, existing scheme 2 does not consider the influence of communication information modulated by the OFDM signal on parameter estimation, which is not conducive to the fusion processing of OFDM radar and communication signals and target localization.

[0064] In view of this, the present invention provides a radar communication integrated positioning method and system based on joint estimation of angle and time delay, which realizes the functions of target positioning and data communication with a single signal waveform. It can realize joint estimation and automatic pairing of angle and time delay, thereby achieving target positioning and transmission of communication information.

[0065] Please see Figure 1 As shown, Figure 1This is a flowchart of a radar-communication integrated positioning method based on joint angle delay estimation provided by an embodiment of the present invention. The radar-communication integrated positioning method based on joint angle delay estimation provided by the present invention includes:

[0066] S101. Construct an integrated radar communication signal, wherein the integrated radar communication signal includes multiple pulses, and each pulse includes multiple OFDM symbols.

[0067] Specifically, this embodiment uses OFDM signals. Orthogonal Frequency Division Multiplexing (OFDM) signals are widely used due to their advantages such as suitability for high-speed data transmission, high spectral efficiency, and strong anti-fading capability. However, in traditional methods, OFDM signals have significant differences in communication and radar applications, and their waveform designs are also different. Therefore, it is necessary to design an integrated signal based on meeting the requirements of a millimeter-wave radar-communication integrated system.

[0068] Please see Figure 2 As shown, Figure 2 This is a schematic diagram of an OFDM radar signal in the prior art provided by the embodiments of the present invention. In the prior art, each pulse in the radar signal transmits only one OFDM symbol; thus, on the one hand, the data rate of the transmitted signal is limited to a certain extent; on the other hand, it is quite different from the communication frame structure and cannot be interconnected with the existing data link network.

[0069] Please see Figure 3 As shown, Figure 3 This is a schematic diagram of an integrated OFDM radar-communication signal provided in an embodiment of the present invention. In this embodiment, a pulse waveform is adopted in the integrated radar-communication signal. Each pulse includes multiple OFDM symbols, which can improve the data transmission rate of the signal under the same bandwidth. Furthermore, the pulse composed of multiple OFDM symbols can be regarded as a time slot in the communication, making the pulse and the communication signal more similar. That is, communication can be completed within one pulse, and synchronization is easier to achieve compared with traditional OFDM radar waveforms.

[0070] The integrated radar-communication signal designed in this embodiment includes N. p N pulses, each pulse consisting of N s It consists of N OFDM symbols. c There are subcarriers, the subcarrier spacing is Δf, and the OFDM symbol length is T. s The pulse repetition period is T p Based on the above basic parameters, the expression for the obtained radar-communication integrated signal s(t) is:

[0071]

[0072] Where, N p N represents the number of pulses included in the integrated radar-communication signal, where p is the p-th pulse. s The number of OFDM symbols included in each pulse, where s is the s-th OFDM symbol, and N c The OFDM symbol includes the number of subcarriers, where n is the nth subcarrier, and d p,s,n Let e ​​be the communication information carried by the nth subcarrier in the s-th OFDM symbol of the p-th pulse, j be the imaginary unit, π be pi, c be the speed of light, Δf be the subcarrier interval, t be time, and T be the time interval. s T is the length of the OFDM symbol. p represents the pulse repetition period, and rect[·] is a rectangular window function.

[0073]

[0074]

[0075] Wherein, the total bandwidth of the transmitted signal B = N c Δf.

[0076] S102. Construct an integrated radar-communication echo reception model, and preprocess the echo signal in the integrated radar-communication echo reception model to obtain the processed echo signal.

[0077] Specifically, in this embodiment, firstly, it is necessary to construct an integrated radar and communication echo reception model. The array elements in the integrated radar and communication echo reception model are used to receive the echo signal after encountering a target.

[0078] Optionally, the integrated radar-communication echo reception model includes M linear array elements arranged uniformly, forming an array. The signal source and the array satisfy narrowband far-field conditions. The echo signal arriving at different array elements corresponds to different echo paths, i.e., including L... p There are 10 echo paths, and the propagation delay τ of the echo signal in the i-th echo path is given. i for:

[0079]

[0080] Where i is the i-th echo path, i = 1, 2, ..., L p L p R is the number of paths the echo signal takes to reach each array element. i Let be the distance to the i-th target.

[0081] Please see Figure 4As shown, Figure 4 This is a schematic diagram of an integrated OFDM radar-communication echo reception model provided in an embodiment of the present invention. Typically, the cyclic prefix of the OFDM echo signal is greater than or equal to the maximum delay of the multipath channel. Therefore, the integrated OFDM radar-communication echo reception model for receiving echo signals is as follows: Figure 4 As shown.

[0082] Please continue reading Figure 4 As shown, in practice, the starting position of the echo signal in echo path one cannot be directly obtained from the echo signal received by the OFDM radar communication integrated echo receiving model, that is, the data processing area in echo path one cannot be directly confirmed. In this embodiment, in order to better utilize the OFDM radar communication integrated echo receiving model, the symbol synchronization method in communication is used to preprocess the echo signal.

[0083] It should be noted that in OFDM communication systems, in order to perform N-point FFT demodulation at the receiver, accurate sampling of the transmitted signal is required within the OFDM symbol period. This can also be understood as the need to perform symbol timing synchronization in order to detect the starting point of each OFDM symbol. This helps to obtain accurate sampling. Since determining the starting position of the echo path is similar to the purpose of timing synchronization in communication, this embodiment uses the method of estimating symbol timing offset (STO) in OFDM communication systems to preprocess the echo signal.

[0084] In this embodiment, please refer to Figure 5 As shown, Figure 5 This is a schematic diagram of the Park algorithm provided in an embodiment of the present invention. Considering the multipath situation in the integrated radar-communication echo reception model, the Park algorithm is used to preprocess the echo signal. Specifically, the echo signal in echo path one received by the integrated radar-communication echo reception model is used as the training symbol, and the echo signals in other echo paths are used as the data symbols. The data processing region in the training symbol is divided into four segments, and the region has a symmetrical and conjugate relationship. The length of each segment is T. e / 4,T e Given the length of the effective OFDM symbols, the pseudo-random sequence is processed by IFFT to obtain basic sequence unit A. Unit A is then subjected to a symmetric transformation to obtain unit B. Based on unit A, unit A is obtained. * Based on unit B, obtain unit B. * , where unit A and unit A * Conjugate, Unit B and Unit B * Conjugate.

[0085] The symbolic timing metric function for Park's algorithm is:

[0086]

[0087] Where, N e denoted as the number of valid OFDM symbols, g represents the timed estimated sample point location, n is the step size variable, and w(·) represents the sliding window sampling data.

[0088] It should be noted that, please refer to Figure 6 As shown, Figure 6 This is a schematic diagram of a symbol timing simulation of the Park algorithm provided in this embodiment of the invention. The Park algorithm performs related calculations starting from both sides of the key positions of the training symbols. During the calculation process, symmetry and conjugate relationships play a weighting role in the summation process, which can cause a large difference in the numerical value of the summation results of adjacent terms. The timing metric curves under different signal-to-noise ratios are shown in the diagram. Figure 6 visible, Figure 6 The signal-to-noise ratios from left to right are 20dB, 10dB, and 0dB, respectively. In addition, it should be noted that in terms of the integrated transmission waveform, in order to use the training symbol for symbol synchronization, the first OFDM signal in the integrated OFDM radar waveform needs to be replaced with the training symbol, while the rest remain unchanged.

[0089] The Park algorithm is used to preprocess the echo signal, and the processed echo signal at time t is obtained. Its expression is:

[0090]

[0091] Among them, a i Let w(t) be the complex fading coefficient of the i-th echo path, and w(t) be additive complex white Gaussian noise. To transmit a signal, f c For carrier frequency;

[0092] Based on the processed echo signal at time t Acquire the echo signal received by the m-th array element Its expression is as follows:

[0093]

[0094] Where, τ i,m Let the propagation delay of the i-th echo path on the m-th array element be given. For a uniform linear array, we can obtain:

[0095]

[0096] Where d is the element spacing, θ i Let be the angle of arrival of the i-th echo.

[0097] The echo signal received by the m-th array element Down-convert to baseband and remove the cyclic prefix to obtain the m-th array element, p-th pulse, and s-th OFDM symbol, expressed as:

[0098]

[0099] Where n is the nth subcarrier;

[0100] For the m-th array element, p-th pulse, and s-th OFDM symbol, at a rate of bandwidth B (N times 1 / T) e Discretization sampling is performed to obtain the k-th sampling result, and its expression is:

[0101]

[0102] Where t=kT e / N,k=0~N c -1, w m (k,s,p) represents the sampled Gaussian white noise;

[0103] Based on the characteristics of OFDM symbols, the subcarrier spacing Δf = 1 / T included in an OFDM symbol. e And in this term of formula (1) The time delay mdsinθ generated on different array elements i / c relative to τ i This can be ignored, and formula (1) can be simplified to:

[0104]

[0105] Among them, f c For carrier frequency;

[0106] Based on the sampling results, the echo signal r received by the m-th array element is obtained. m (s,p), its expression is:

[0107]

[0108] r m (s,p)=[r m (0,s,p),r m (1,s,p),…,r m (N c -1,s,p)];

[0109] r m (s,p) represents the p-th pulse and s-th symbol received by the m-th array element from the echo;

[0110]

[0111] This represents the steering vector on the m-th array element that is related to the i-th echo path;

[0112] D(s,p) = diag[d(s,p)];

[0113] Convert the d(s,p) vector into a diagonal matrix;

[0114]

[0115] D(s,p) represents the communication data modulated on the p-th pulse and s-th symbol of the received echo;

[0116] N in c =N;

[0117] Can It is approximately the inverse discrete Fourier transform matrix;

[0118]

[0119] b(τ i This indicates the relationship between echo delay and OFDM subcarrier spacing;

[0120] w m (s,p)=[w m (0,s,p),w m (1,s,p),…,w m (N c -1,s,p)];

[0121] w m (s,p) represents the noise of the m-th array element when it receives the p-th pulse and s-th symbol of the echo;

[0122] in,() T Represents the transpose of a matrix;

[0123] S103. Eliminate the communication information in the processed echo signal and obtain the echo signal after eliminating the communication information.

[0124] Specifically, in this embodiment, for the integrated radar-communication signal system, the communication information carried by the transmitted integrated radar-communication signal is known; that is, the communication code modulated on each transmitted OFDM symbol is known. Therefore, communication information can be eliminated from the echo signal received by the integrated radar-communication echo receiver model. Since the angle and time delay parameters are included in the phase information in the frequency domain, the received echo signal needs to be transformed into the frequency domain, and the communication information in the echo signal is eliminated based on the known transmission information.

[0125] In the integrated radar-communication echo reception model, the data processing area in each echo signal can be accurately obtained through the synchronous positioning method, providing a prerequisite for accurately eliminating communication information in the echo signal; the echo signal r received by the m-th array element is obtained as described above. m (s,p), that is, by performing a frequency domain transformation using formula (2) and eliminating the communication information D(s,p), we can obtain:

[0126]

[0127] Among them, D -1 (s,p) is the inverse matrix of the communication information D(s,p), and F is the discrete Fourier transform matrix;

[0128] Simplifying formula (3), we get:

[0129]

[0130] n m (s,p)=D -1 (s,p)Fw m (s,p);

[0131] According to formula (4), After the communication information is eliminated, the expressions for the p-th pulse and s-th OFDM symbol received by the M array elements are:

[0132]

[0133]

[0134] y(s,p) represents the channel frequency domain vector and noise received by the M array elements for the p-th pulse and s-th symbol after communication information is eliminated;

[0135]

[0136] Where n(s,p) represents the noise of the M array elements when receiving the channel frequency vector of the p-th pulse and s-th symbol after the communication information is eliminated;

[0137] Based on the p-th pulse and s-th OFDM symbol received by the M array elements, the p-th pulse received by the M array elements is obtained, and its expression is:

[0138]

[0139]

[0140] Y represents the channel frequency domain vector and noise received by the M array elements from the p-th pulse after the communication information is eliminated;

[0141]

[0142] H represents the channel frequency vector received by the M array elements from the p-th pulse after the communication information is eliminated;

[0143]

[0144] N represents the noise of the M array elements when receiving the channel frequency domain vector of p pulses after communication information is eliminated.

[0145] According to formula (6), after sampling and preprocessing the OFDM radar-communication integrated signal received by M array elements, the obtained frequency domain data is similar to that of an array with MN array elements. c The uniform linear array received N s The second snapshot, compared to the time-domain signal received by the original M array elements, realizes array element expansion in the frequency domain, which can further improve the parameter estimation accuracy.

[0146] S104. Based on the echo signal that has eliminated communication information, the angle parameter and time delay parameter are estimated sequentially to obtain the angle parameter and time delay parameter in order to achieve target positioning.

[0147] Specifically, in this embodiment, the angle and time delay parameters of the frequency domain response in formula (6) are estimated based on the echo signal that eliminates communication information.

[0148] Obtain the channel frequency domain response estimation vector x for the m-th array element, the p-th pulse, and the s-th OFDM symbol. m Its expression is:

[0149]

[0150] x m =[x m (0),x m (1),…,x m (N c -1)] T ;

[0151] x m This represents the channel frequency domain response estimation vector and noise for the m-th array element, the p-th pulse, and the s-th OFDM symbol;

[0152] H m =[H m (0),H m (1),…,H m (N c -1)] T ;

[0153] H mThis represents the channel frequency domain response estimation vector for the m-th array element, the p-th pulse, and the s-th OFDM symbol;

[0154]

[0155] a′ represents the complex fading coefficient vector after correction of all echo paths;

[0156]

[0157] a′ i This represents the complex fading coefficient vector after correction for the i-th echo path;

[0158] n m =[n m (0),n m (1),…,n m (N c -1)] T ;

[0159] n m This represents the noise when estimating the channel frequency domain response vector for receiving the m-th array element, the p-th pulse, and the s-th OFDM symbol;

[0160] In the above formula (7), J m (τ,θ) represents the extraction of information related to time delay and angle from the channel frequency domain response estimation vector, J m The expression for (τ,θ) is:

[0161]

[0162] in,

[0163] Based on the channel frequency domain response estimation vector x of the m-th array element, the p-th pulse, and the s-th OFDM symbol. m Along the spatial dimension, the channel frequency domain response estimation vector x of M array elements is obtained, and its expression is:

[0164]

[0165]

[0166]

[0167] n represents the noise when obtaining the channel frequency domain response estimation vector of M array elements.

[0168] It should be noted that for the problem of joint estimation of angle parameters and time delay parameters, it is necessary to first obtain information containing angle parameters and time delay parameters from the channel frequency domain response, and to make reasonable and effective use of the obtained information. In view of this, this embodiment adopts a subspace algorithm to realize the joint estimation of angle parameters and time delay parameters according to the signal pattern of the channel frequency domain response.

[0169] On the one hand, the process of obtaining angle parameters includes:

[0170] Expanding J(θ,τ) in formula (8), its expression is as follows:

[0171]

[0172] According to the characteristics of formula (9), we can see that by introducing matrices A and J... m (θ,τ)=J m-1 (θ,τ)A=J0(θ,τ)A m The expression for matrix A is:

[0173]

[0174] Formula (8) can be expressed as:

[0175]

[0176] For the same pulse N s The covariance matrix R of the channel frequency domain response estimation vector x composed of OFDM symbols is calculated and subspace decomposition is performed. Its expression is:

[0177]

[0178] in, According to formula (6), it can be deduced that the angle parameter and time delay parameter contained in the channel frequency domain response estimation vector x are the same, only the sampling noise R is different. a′a' Different, R a′a' =E[a'a' H ], To expand the signal subspace, For the noise subspace, according to formula (11), the extended signal subspace U S There exists a matrix V spanned by J(θ,τ) such that U S The expression is:

[0179]

[0180] in, Let J(θ,τ) be the generalized inverse matrix, and let V be an invertible matrix.

[0181] According to formula (12), the difference information reflected between the frequency domain responses of the echo signals received by each array element contains parameters related to the target's angle of arrival. The angle of arrival of the target can be estimated based on the frequency domain responses of the signals received by different array elements.

[0182] Get U S (M-1)×N c Rows form matrix U S1 , and U S (M-1)×N c Rows constitute U S2 U S1 and U S2 The expression is:

[0183]

[0184] Will U S2 The expression can be further rewritten as:

[0185]

[0186] Where Ψ=V -1 Let AV, Ψ, and A be similar matrices, where the diagonal elements of matrix A are the eigenvalues ​​of Ψ, and matrix V is the eigenvector of matrix Ψ. By obtaining matrix Ψ, we can utilize its eigenvalues. Parameters for estimating the target's angle of arrival Its expression is:

[0187]

[0188] The angle parameters are obtained through the above process.

[0189] On the other hand, the process of obtaining the delay parameter includes:

[0190] According to J0(θ,τ) in formula (9), it can be found that J0(θ,τ) contains only parameters related to the target arrival time delay, while the other matrices in J(θ,τ) contain parameter information related to the target arrival angle. Thus, the difference information between these matrices can be used to estimate the target arrival angle. Similarly, a similar method can be used to estimate the target arrival time delay.

[0191] First, we introduce a commutation matrix C to construct a matrix U containing the angle of target arrival. D Matrix U D The expression is:

[0192]

[0193] In this case, matrix Q is similar to matrix V, both being L p ×L p Invertible matrix;

[0194] The expressions for K0(θ,τ) and T in formula (13) are:

[0195]

[0196] in,

[0197] Thus, through the above transformation, a matrix containing the target arrival angle information is obtained. Then, a method similar to target angle estimation can be used to estimate the target arrival delay.

[0198] Get U D The front (N) c -1)×M rows form a matrix U D1 , and U D After (N) c -1)×M rows constitute U D2 U D1 and U D2 The expression is:

[0199]

[0200] Will U D2 The expression can be further rewritten as:

[0201]

[0202] Based on the angle parameter estimation, the matrix T in formula (12) is decomposed into eigenvalues ​​to obtain the eigenvalues. Further, time delay parameter estimates can be obtained. Its expression is:

[0203]

[0204] By correlating the echo paths of matrix A and matrix T in formula (13), the estimated angle parameters are obtained. With delay parameters It can automatically pair in real time, which can effectively improve algorithm efficiency.

[0205] Based on the same inventive concept, this invention also provides a radar-communication integrated positioning system based on joint angle and time delay estimation, comprising:

[0206] The signal transmission module is used to construct an integrated radar-communication signal, which includes multiple pulses, each pulse including multiple OFDM symbols.

[0207] The echo signal receiving module is used to construct an integrated radar-communication echo receiving model and to preprocess the echo signals in the integrated radar-communication echo receiving model to obtain the processed echo signals.

[0208] The echo signal processing module is used to remove communication information from the processed echo signal and obtain the echo signal after removing the communication information.

[0209] The target localization module is used to estimate the angle parameters and time delay parameters sequentially based on the echo signal after communication information is eliminated, and obtain the angle parameters and time delay parameters in order to achieve target localization.

[0210] In an optional embodiment of the present invention, the effects of the method provided by the present invention are further illustrated by the following simulation experiments. Please refer to Table 1, which shows the simulation parameters of the radar-communication integrated system.

[0211] Table 1 Simulation parameters of the MIMO-OFDM radar-communication integrated system

[0212]

[0213] Please see Figure 7 As shown, Figure 7 This is a schematic diagram of a scatter plot of the joint angle and time delay target estimation position provided in an embodiment of the present invention. Figure 7 This displays the location results of the estimated points for angle and time delay parameters in 100 Monte Carlo simulation experiments; by Figure 7 As can be seen, at a signal-to-noise ratio of 0dB, the estimated points for angle and time delay parameters can be concentrated near the corresponding positions of the target without being scattered, indicating that the estimated arrival angle and time delay of the target are relatively accurate; and the angle and time delay parameters of the three targets are accurately paired, further verifying the efficiency of the method provided in this embodiment.

[0214] Please see Figure 8 As shown, Figure 8 This is a schematic diagram illustrating the comparison between the angle-delay joint target estimation position and the actual position provided in an embodiment of the present invention. Figure 8 As can be seen, for a more intuitive comparison, the target arrival time delay on the horizontal axis was converted into target distance information; from Figure 8 As can be seen, the difference between the actual and estimated positions of the target is small, with an average positioning error of less than 1m. Therefore, relatively accurate target positioning can be achieved even with a low signal-to-noise ratio of 0dB.

[0215] Please see Figures 9(a) to 9(b) As shown, Figure 9(a) is a schematic diagram of an angle parameter estimation error provided by an embodiment of the present invention, and Figure 9(b) is a schematic diagram of a time delay parameter estimation error provided by an embodiment of the present invention. The angle estimation error is defined as follows: Delay estimation error Where i is the number of targets, i = 0, 1, ..., L p -1; The signal-to-noise ratio was modified to 5dB, and the angle estimation error and time delay estimation error were shown in Figure 9(a) and Figure 9(b). As can be seen from the simulation figures, after 100 Monte Carlo simulation experiments, the angle estimation error can be kept within ±0.05° and the time delay estimation error can be kept within ±1ns. Therefore, the target position error can be estimated to be less than 0.2m, proving that the method provided in this embodiment can achieve high-precision target positioning at a signal-to-noise ratio of 5dB.

[0216] Please see Figures 10 to 11 As shown, Figure 10 This is a schematic diagram illustrating the relationship between the target positioning error and the signal-to-noise ratio in the joint estimation of angle and time delay provided by an embodiment of the present invention. Figure 11 This is a schematic diagram illustrating the relationship between the angle and time delay joint estimation target positioning error and the number of symbols provided in this embodiment of the invention. In the case of multipath propagation, the target positioning error varies with the signal-to-noise ratio and the number of symbols. In this embodiment, the positioning error is defined using the root mean square error (RMSE) of the estimated target position. The coordinates of the target in a two-dimensional plane can be obtained using angle and time delay information. Then, the RMS error between the target's true position and its estimated position can be calculated.

[0217]

[0218] Where N represents the Monte Carlo number, For the estimated target position coordinates, x i The actual position coordinates of the target are shown in Table 1, except for the changes in the dependent variable parameters. As the signal-to-noise ratio increases, the positioning error in Figure 9 also decreases continuously. When the signal-to-noise ratio is around 0dB, the positioning error is already less than 1m, which shows that the method provided in this embodiment has the characteristics of high-precision target positioning. Figure 10 Simulation results show that as the number of symbols increases, the target positioning error also decreases. According to the previous analysis, the number of symbols in the angle and time delay joint estimation method can be understood as the number of snapshots of the received echo signal. According to the array signal processing theory, as the number of snapshots increases, the signal covariance matrix estimation will be more accurate, which can also make the angle and time delay parameter estimation error smaller and the positioning more accurate.

[0219] Please see Figure 12 As shown, Figure 12This is a schematic diagram of the communication bit error rate (BER) curve of the OFDM radar-communication integrated signal provided in this embodiment of the invention. It shows the BER variation with signal-to-noise ratio (SNR) under different modulation orders for the OFDM radar-communication integrated waveform. In the simulation, the communication channel is a Gaussian white noise channel, and the OFDM signal is modulated using Phase Shift Keying (PSK). The simulation results show that as the SNR increases, the BER decreases; however, as the modulation order (communication data rate) increases, the BER also increases. Therefore, a trade-off between BER and communication data rate needs to be considered in the design of the radar-communication integrated system.

[0220] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0221] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0222] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A radar-communication integrated positioning method based on joint estimation of angle and time delay, characterized in that, include: A radar-communication integrated signal is constructed, wherein the radar-communication integrated signal includes multiple pulses, and each pulse includes multiple OFDM symbols; An integrated radar-communication echo reception model is constructed, and the echo signal in the integrated radar-communication echo reception model is preprocessed to obtain the processed echo signal; wherein, the echo signal is the entire OFMD symbol, which includes the cyclic prefix T. cp and data processing area; using the Park algorithm to preprocess the echo signal to obtain the data processing area in the echo signal; including: The echo signal is preprocessed using the Park algorithm to obtain the processed echo signal at time t. Its expression is: Among them, a i Let w(t) be the complex fading coefficient of the i-th echo path, and w(t) be additive complex white Gaussian noise. To transmit a signal, f c For carrier frequency, L p The number of paths for the echo signal to reach each array element, i = 1, 2, ..., L p , τ i s(t) represents the time delay of the echo signal propagation, and s(t) represents the integrated radar-communication signal. Based on the echo signal processed at time t Obtain the echo signal received by the m-th array element. The echo signal received by the m-th array element Down-convert to baseband and remove the cyclic prefix to obtain the m-th array element, p-th pulse, and s-th OFDM symbol; The m-th array element, the p-th pulse, and the s-th OFDM symbol are discretized and sampled at a rate with a bandwidth of B. Based on the sampling results, the echo signal r received by the m-th array element is obtained. m (s,p); The communication information in the processed echo signal is removed to obtain the echo signal after the communication information is removed; Based on the echo signal that has had its communication information eliminated, the angle parameters and time delay parameters are estimated sequentially to obtain the angle parameters and time delay parameters in order to achieve target positioning.

2. The radar-communication integrated positioning method based on joint estimation of angle and time delay according to claim 1, characterized in that, The expression for the integrated radar-communication signal s(t) is: Where, N p The number of pulses included in the integrated radar-communication signal, where p is the p-th pulse, and N... s The number of OFDM symbols included in each pulse, where s is the s-th OFDM symbol, and N c The OFDM symbol includes the number of subcarriers, where n is the nth subcarrier, and d p,s,n Let e ​​be the communication information carried by the nth subcarrier in the s-th OFDM symbol of the p-th pulse, j be the imaginary unit, π be pi, c be the speed of light, Δf be the subcarrier spacing, t be time, and T be the time interval. s T is the length of the OFDM symbol. p represents the pulse repetition period, and rect[·] is a rectangular window function.

3. The radar-communication integrated positioning method based on joint estimation of angle and time delay according to claim 1, characterized in that, The integrated radar-communication echo reception model comprises M uniformly arranged linear array elements; wherein, the echo signal arriving at different array elements corresponds to different echo paths, and the propagation delay τ of the echo signal in the i-th echo path is... i for: Where i is the i-th echo path, i = 1, 2, ..., L p L p R is the number of paths the echo signal takes to reach each array element. i Let be the distance from the target via the i-th echo path.

4. The radar-communication integrated positioning method based on joint estimation of angle and time delay according to claim 1, characterized in that, For the echo signal r m (s,p) is used for frequency domain transformation to eliminate communication information in the echo signal.

5. The radar-communication integrated positioning method based on joint estimation of angle and time delay according to claim 1, characterized in that, The process of obtaining the angle parameter includes: Obtain the channel frequency domain response estimation vector x for the m-th array element, the p-th pulse, and the s-th OFDM symbol. m ; Based on the channel frequency domain response estimation vector x of the m-th array element, p-th pulse, and s-th OFDM symbol. m Along the spatial dimension, obtain the channel frequency domain response estimation vector x of M array elements; Obtain the angle and time delay parameters in the channel frequency domain response estimation vector x of M array elements, and for the same pulse N s The covariance matrix R of the channel frequency domain response estimation vector x composed of OFDM symbols is calculated and subspace decomposition is performed. Obtain the intermediate matrix V, and based on the intermediate matrix V, obtain the extended signal subspace U after the subspace decomposition of the covariance matrix R. S ; The extended signal subspace U obtained from the decomposition of the covariance matrix R S Obtain matrix Ψ; and obtain the angle parameters based on the eigenvalues ​​of matrix Ψ.

6. The radar-communication integrated positioning method based on joint estimation of angle and time delay according to claim 1, characterized in that, The process of obtaining the delay parameter includes: Obtain the channel frequency domain response estimation vector x for the m-th array element, the p-th pulse, and the s-th OFDM symbol. m ; Based on the channel frequency domain response estimation vector x of the m-th array element, p-th pulse, and s-th OFDM symbol. m Along the spatial dimension, obtain the channel frequency domain response estimation vector x of M array elements; Obtain the angle and time delay parameters in the channel frequency domain response estimation vector x of M array elements, and for the same pulse N s The covariance matrix of the channel frequency domain response estimation vector x composed of OFDM symbols is calculated, and subspace decomposition is performed to obtain the subspace decomposition matrix R. Obtain the commutation matrix C, and then, based on the commutation matrix C and the extended signal subspace U in the subspace decomposition matrix R... S Obtain matrix U D ; According to the matrix U D Obtain eigenvalues And based on the characteristic value Obtain delay parameters 7. A radar-communication integrated positioning system based on joint estimation of angle and time delay, characterized in that, include: A signal transmission module is used to construct an integrated radar-communication signal, wherein the integrated radar-communication signal includes multiple pulses, and each pulse includes multiple OFDM symbols; An echo signal receiving module is used to construct an integrated radar-communication echo receiving model and preprocess the echo signals in the integrated radar-communication echo receiving model to obtain the processed echo signals; wherein, the echo signal is the entire OFMD symbol, which includes the cyclic prefix T. cp and data processing area; using the Park algorithm to preprocess the echo signal to obtain the data processing area in the echo signal; including: The echo signal is preprocessed using the Park algorithm to obtain the processed echo signal at time t. Its expression is: Among them, a i Let w(t) be the complex fading coefficient of the i-th echo path, and w(t) be additive complex white Gaussian noise. To transmit a signal, f c For carrier frequency, L p The number of paths for the echo signal to reach each array element, i = 1, 2, ..., L p , τ i s(t) represents the time delay of the echo signal propagation, and s(t) represents the integrated radar-communication signal. Based on the echo signal processed at time t Obtain the echo signal received by the m-th array element. The echo signal received by the m-th array element Down-convert to baseband and remove the cyclic prefix to obtain the m-th array element, p-th pulse, and s-th OFDM symbol; The m-th array element, the p-th pulse, and the s-th OFDM symbol are discretized and sampled at a rate with a bandwidth of B. Based on the sampling results, the echo signal r received by the m-th array element is obtained. m (s,p); The echo signal processing module is used to remove communication information from the processed echo signal and obtain the echo signal after removing the communication information. The target localization module is used to estimate the angle parameters and time delay parameters sequentially based on the echo signal after communication information has been eliminated, and obtain the angle parameters and time delay parameters in order to achieve target localization.

Images