Distributed radar-communication integration method based on delay-doppler joint modulation

Abstract

The application discloses a distributed radar-communication integration method based on time delay-Doppler joint modulation, comprising the following steps: acquiring a radar-communication integration signal received by a receiving end, extracting a communication signal echo and a radar signal echo from the radar-communication integration signal; acquiring target time delay, path gain and Doppler information by using a cross-correlation method according to the radar signal echo; demodulating the communication signal echo by using a turbo iterative maximum ratio combining algorithm to obtain communication data in a time delay-Doppler domain grid; and positioning and measuring the speed of the target by using a chan method according to the target time delay and Doppler information, so as to obtain a target positioning and speed measuring result.

Description

TECHNICAL FIELD

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

[0002] With the rapid development of electronic information technology, the differences between radar perception and wireless communication in terms of transceiver channels, signal and data processing, management and control are gradually narrowing, and an integration trend has emerged. After years of research by domestic and foreign experts and scholars, the integrated system has undergone the development and evolution of independent structure, joint structure and comprehensive structure, and has achieved preliminary results in the integration of control and display, processing, channel and aperture. Now it is developing towards signal integration in electromagnetic space.

[0003] However, due to the constraints of classical radar detection theory, Shannon information theory and other basic theories, the classical orthogonal frequency division multiplexing (OFDM) communication signal is not suitable for radar detection. Specifically, there are pseudo-peak and high sidelobe problems in the ambiguity function of the OFDM communication signal, which leads to the signal being unable to have excellent radar detection performance. In addition, the Doppler tolerance of the integrated signal based on OFDM technology is low, and it cannot meet the high dynamic application scenario.

[0004] Therefore, some scholars proposed a new modulation method based on orthogonal time frequency space (OTFS), which effectively solves the influence of time-varying channel by transmitting signals in the time delay-Doppler domain.

[0005] The OTFS-based radar-communication integrated method is still an open problem to be solved. In a published paper "GAUDIO L, KOBAYASHI M, BISSINGER B, et al. Performance analysis of joint radar and communication using OFDM and OTFS [C] / / 2019IEEE International Conference on Communications Workshops. Shanghai, China. IEEE, 2019: 1-6.", OTFS signals are used in a radar-communication integrated system, and it is proved that the performance limit of OTFS signals for radar target detection and parameter estimation is consistent with that of traditional radar signals, and full-frame symbols are used for radar detection. However, the radar point spread function of the full-frame OTFS symbol containing the communication signal echo with large amplitude and phase fluctuations usually has high sidelobes, which may introduce false targets and drown out small targets. SUMMARY

[0006] The technical problem to be solved by the present application is to effectively balance the excellent radar detection performance and high-speed wireless communication performance in a high-speed mobile scene, and to greatly reduce the resources required for detection function through multi-station cooperative radar system.

[0007] To solve the above problems, the present application provides a distributed radar-communication integrated method based on time-delay-Doppler joint modulation, which bypasses the time-frequency dimension and performs integrated design and processing in the time-delay-Doppler domain, thereby combining excellent wireless communication and radar detection performance (especially suitable for high-speed mobile scenarios).

[0008] To achieve the above object, the present application adopts the following technical scheme:

[0009] In a first aspect, a distributed radar-communication integrated method based on time-delay-Doppler joint modulation is provided, comprising:

[0010] Step S1, in response to the transmission station transmitting a radar-communication integrated signal based on time-delay-Doppler joint modulation, obtaining the radar-communication integrated signal received by the receiving end, the radar-communication integrated signal comprising three parts of radar signal, communication signal and guard interval;

[0011] Step S2, extracting the communication signal echo and the radar signal echo from the radar-communication integrated signal; obtaining target time delay, path gain and Doppler information according to the radar signal echo using cross-correlation method;

[0012] Step S3, according to the target delay, path gain and Doppler information, the turbo iterative maximum ratio combining algorithm is used to demodulate the communication signal echo, and the communication data in the delay-Doppler domain grid is obtained;

[0013] Step S4, according to the target delay and Doppler information, the chan method is used to locate and measure the speed of the target, and the target location and speed measurement result is obtained, including the target coordinate position and the target moving speed.

[0014] In some embodiments, in step S1, the construction process of the radar communication integrated signal includes:

[0015] S1.1, the guard interval length l max for the maximum delay spread in multipath, denotes the guard interval caused by the maximum Doppler of the target, denotes the guard interval additionally increased due to fractional Doppler, and the guard interval parameter in the Doppler dimension is equal to The delay-Doppler domain signal is represented as X[m, k]; wherein the delay-Doppler domain signal is composed of M subcarriers and N symbols, k=0, 1,...N-1 and m=0, 1,...M-1 represent the Doppler and delay index index respectively;

[0016] S1.2, the delay-Doppler domain signal X[m, k] is obtained by discrete Zak inverse transform to obtain the delay-time domain signal

[0017]

[0018] Wherein n=0, 1,...N-1, m=0, 1,...M-1;

[0019] S1.3, the delay-time domain signal is converted to a discrete time domain signal s[q] by serial conversion;

[0020]

[0021] Wherein, q=m+nM;

[0022] S1.4, the discrete time domain signal s[q] is converted to a radar communication integrated signal s(t) by digital-to-analog conversion, which is used for transmission station to transmit.

[0023] In some embodiments, in step S1, the radar communication integrated method is carried out in the mode of "one sending and three receiving", that is, one transmission station corresponds to three receiving ends.

[0024] In some embodiments, in step S2, the target delay, path gain and Doppler information are obtained by using the cross-correlation method according to the radar signal echo, including:

[0025] S2.1, the radar transmit signal X in delay-Doppler domain i,j The expression of [m, k] is:

[0026]

[0027] Where k, m represent the Doppler and delay index value of the delay-Doppler grid respectively; i, j represent the delay and Doppler grid index value of the delay-Doppler grid where the radar signal is located respectively;

[0028] S2.2, the pulse response H of the radar signal i,j The expression of [m, k] is:

[0029]

[0030] Where P represents the number of paths, h p represents the gain of the pth path, represents the phase shift caused by Doppler shift, φ p is the initial phase, represents the Doppler index of the pth path in the delay-Doppler domain, represents the delay index of the pth path in the delay-Doppler domain;

[0031]

[0032] S2.3, the pulse response H of the radar signal i,j [m, k] is cross-correlated with the intermediate parameter ζ N to obtain the cross-correlation function

[0033]

[0034] Suppose there is a single target on the lth delay grid, and the radar signal is in the delay-Doppler domain m = M - l max , k = N / 2; D is the required resolution of the fractional Doppler κ; when the estimated Doppler index matches the actual Doppler index of the pth path , the cross-correlation function reaches a maximum value, that is, ^ represents the estimated value;

[0035] S2.4, by finding the maximum amplitude of the function about , the target parameters of the lth delay grid are estimated:

[0036]

[0037] In a multi-objective scenario, the decision to stop estimating a target is to satisfy at least one of the following two conditions:

[0038]

[0039] Where α is 1 / 50, β is 1 / 10, and σ is the noise standard deviation;

[0040] This yields the target time delay. Path gain h p and Doppler information.

[0041] In some embodiments, step S3, demodulating the communication signal echo using the turbo iterative maximum ratio combining (MRC) algorithm based on the target time delay, path gain, and Doppler information to obtain communication data in the time delay-Doppler domain grid, includes:

[0042] Delay-time domain channel response for:

[0043]

[0044] Where P represents the number of paths, h p This represents the gain of the p-th path. This represents the Doppler index of the p-th path in the delay-Doppler domain. The delay exponent represents the delay index of the p-th path in the delay-Doppler domain;

[0045] Channel response matrix in the delay-time domain for:

[0046]

[0047] Defined at the i-th th The residual noise plus interference RNPI term in the next iteration is:

[0048]

[0049] in, This refers to the residual error in reconstructing the received delay – the time-domain symbol – caused by estimation errors in the transmitted symbols. Symbolic vector It is estimated in ascending order of m = 0, ..., M-1;

[0050] The ith iteration for:

[0051]

[0052] in, It contains of all delay taps of the channel where the maximum ratio combination of RNPIs; A * denotes the complex conjugate of A, denotes the multiplication of matrix elements;

[0053] the MRC output of the i th th iteration is given by

[0054]

[0055] where

[0056]

[0057] In the above equation, denotes the division of matrix elements, denotes the Hermitian transpose of A;

[0058] In the i th th iteration, for each estimated symbol vector the update vector is needed. The RNPI vector update for the latest estimated symbol vector is given by

[0059]

[0060] The MRC detection iteration is stopped when the overall RNPI error does not decrease any more; in one iteration, the overall complexity for computing all symbol vectors and is M(2P+1)N complex multiplications;

[0061] Finally, the estimated vector in delay-time domain is transformed into delay-Doppler domain by N-point DFT to obtain the estimated value of the transmitted symbol vector x m ;

[0062]

[0063] where F N denotes the N-point DFT transform;

[0064] c m (n) is not necessarily exactly in the set of modulation symbols, c m (n) is processed to obtain the communication data in the delay-Doppler domain grid

[0065]

[0066] where Q represents a modulation symbol set used in a communication system, a w represents a modulation symbol, w = 1,..., |Q|, n = 0,..., N-1.

[0067] In step S4, the target is positioned and speeded by using the chan method according to the target time delay, and a target positioning and speeding result is obtained.

[0068] There are one transmitting station, one target and B = 3 user terminals UE, wherein the transmitting station and the user terminals UE are in a static state; the real values of the position and speed of the target to be positioned are respectively represented as u o = [x o , y o , z o ] T and represents the real value of the position of the transmitting station, represents the real value of the position of the user terminal UE; the real value and the measured value of a variable are distinguished by using (.) o and (.) T represents the transpose of a matrix;

[0069] In practice, the real positions of the transmitting station and the user terminals UE are difficult to obtain, and only the measured values s t = [x t , y t , z t ] T and s r,b = [x r,b , y r,b , z r,b ] T (b = 1, 2,..., B), that is:

[0070]

[0071] In formula (401), Δs t and Δs r,b respectively represent the station address errors of the transmitting station and each user terminal UE; the following vector is defined:

[0072]

[0073] In formula (402), s is a measured vector containing the positions of the transmitting station and the user terminals UE, s o is a real vector containing the positions of the transmitting station and the user terminals UE, and Δs is an error vector of the positions of the transmitting station and the user terminals UE; Δs obeys a zero-mean Gaussian distribution, and the covariance matrix of Δs is E[ΔsΔs T ] = Q s ;

[0074] For the receiving end b, the distance difference between the reflection path and the direct path of the target, the positioning equation of the distance difference rate is expressed as:

[0075]

[0076] Wherein,

[0077] Considering that the station site error and the estimation results of the distance difference and the distance difference rate cannot be completely accurate, only the positioning equation containing errors can be obtained, that is:

[0078]

[0079] The formula (405) is expressed in vector form:

[0080] r=r o +Δr

[0081]

[0082] Wherein,

[0083]

[0084] The formula (406) is combined to obtain the overall positioning equation

[0085] α=α o +Δα (408)

[0086] Wherein, represents the positioning parameter measurement vector, represents the true value vector of the positioning parameter, represents the positioning parameter measurement error vector, assuming that Δα obeys zero mean Gaussian distribution, then the covariance matrix of Δα is E[ΔαΔα T ]=Q α .

[0087] Step S4, according to the target time delay, the target is positioned and measured by using chan method, and the target positioning and measuring result is obtained, further comprising:

[0088] The parameters in the distance difference positioning equation are replaced by the measured values, and the terms are removed as:

[0089] R t +R r,b =r b,t +R t,r,b ,(b=1,2,...,B) (409)

[0090] According to the target time delay The distance difference r between the reflection path and the direct path of the target is calculatedb,t The target position coordinate u is obtained by solving formula (409) by using the Chan algorithm.

[0091] The distance difference rate positioning equation in formula (407) is replaced by the measured value, and is expressed as:

[0092]

[0093] The matrix form is:

[0094]

[0095] According to the Doppler The radial velocity of the target is obtained Based on the obtained target position coordinate u and the radial velocity of the target The moving speed of the target is obtained by solving formula (411)

[0096] In a second aspect, the present application provides a distributed radar-communication integrated device based on time-delay-Doppler joint modulation, comprising a processor and a storage medium.

[0097] The storage medium is used for storing instructions.

[0098] The processor is used for operating according to the instructions to execute the steps of the method according to the first aspect.

[0099] In a third aspect, the present application provides a storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the steps of the method according to the first aspect.

[0100] In a fourth aspect, the present application provides a computer device comprising a processor and a storage medium.

[0101] The storage medium is used for storing instructions.

[0102] The processor is used for operating according to the instructions to execute the steps of the method according to the first aspect.

[0103] Compared with the prior art, the present application has the following advantages: the present application provides a distributed radar-communication integrated method based on time-delay-Doppler joint modulation, which has the following advantages: it can have good radar detection performance and high-speed wireless communication performance in a high-speed mobile scene.

[0104] The present application further proposes a multi-station cooperative radar system under the OTFS framework, which avoids the problem of excessive occupation of time-frequency resources by radar. BRIEF DESCRIPTION OF DRAWINGS

[0105] ​Figure 1 is an integrated signal model diagram of an embodiment of the present application.

[0106] Figure 2 is a modulation and demodulation block diagram of a radar communication integrated signal based on delay-Doppler joint modulation in an embodiment of the present application.

[0107] Figure 3 is an elliptical positioning principle diagram in an embodiment of the present application.

[0108] Figure 4 is a system architecture design diagram in an embodiment of the present application.

[0109] Figure 5 is a delay-Doppler domain received signal diagram in an embodiment of the present application.

[0110] Figure 6 is a four-station time difference positioning and velocity measurement system schematic diagram in an embodiment of the present application.

[0111] Figure 7 is a bit error rate diagram under different signal-to-noise ratios in an embodiment of the present application.

[0112] Figure 8 is a radar signal echo diagram in an embodiment of the present application.

[0113] Figure 9 is a positioning and velocity measurement performance of different position targets in an embodiment of the present application. DETAILED DESCRIPTION

[0114] The present application will be further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0115] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, within, etc. are understood as including the number. If it is described as first, second, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0116] In the description of the present application, the description of the reference terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0117] Embodiment 1

[0118] As Figure 1 shown, a distributed radar-communication integration method based on time-delay-Doppler joint modulation includes the following steps:

[0119] Step S1, in response to a transmitting station transmitting a radar-communication integration signal based on time-delay-Doppler joint modulation, obtaining a radar-communication integration signal received by a receiving end, the radar-communication integration signal including three parts of a radar signal, a communication signal, and a guard interval;

[0120] Step S2, extracting a communication signal echo and a radar signal echo from the radar-communication integration signal; and according to the radar signal echo, using a cross-correlation method to obtain target time delay, path gain, and Doppler information;

[0121] Step S3, according to the target time delay, path gain, and Doppler information, using a turbo iterative maximum ratio combining algorithm to demodulate the communication signal echo, and obtaining communication data in a time-delay-Doppler domain grid;

[0122] Step S4, according to the target time delay and Doppler information, using a chan method to locate and measure the speed of the target, and obtaining a target location and speed measurement result, including a target coordinate position and a target moving speed.

[0123] The simulation parameters involved in this embodiment are shown in Table 1:

[0124] Table 1 Simulation parameters involved in this embodiment

[0125]

[0126]

[0127] A radar-communication integration system framework based on time-delay-Doppler joint modulation is shown in Figure 2 Fig. 1, and is implemented according to the following steps 1 to 3:

[0128] Step 1. Integration signal design

[0129] A radar-communication integration signal model based on time-delay-Doppler joint modulation is shown in Figure 1 (a). The integration signal is composed of three parts of a radar signal, a communication signal, and a guard interval. The length of the guard interval l max is the maximum time delay spread in multipath, represents a guard interval caused by the maximum Doppler of a target, represents an additional guard interval caused by fractional Doppler. The function of the guard interval is to avoid mutual interference between the radar signal and the communication signal.Figure 1 (a) The time-delay-time domain signal is obtained by transforming the formula (1), and the signal model is shown in Figure 1 (b). The time-delay-time domain signal is parallel-serial converted to obtain the discrete time domain signal, as shown in Figure 1 (c). It can be seen from the figure that Figure 1 The guard interval at the bottom of the signal in (b) also becomes the guard interval between different symbols in the time domain, which is equivalent to the role of the cyclic prefix. Therefore, there is no need to add additional guard intervals between different symbols in the time domain.

[0130] 1.1) This embodiment considers a time-delay-Doppler domain signal composed of M subcarriers and N symbols. The subcarrier interval is Δf, and the duration of a single symbol is T symbol . Therefore, the total bandwidth of a frame signal, signal duration and the number of Quadrature Amplitude Modulation (QAM) symbols are MΔf, NT symbol and MN respectively. The time delay and Doppler interval are T symbol / M and Δf / N respectively. Let X[m, k] represent the QAM symbol on the time-delay-Doppler two-dimensional grid, where k (k = 0, 1,..., N-1) and m (m = 0, 1,..., M-1) represent the Doppler and time delay index respectively.

[0131] 1.2) After the Inverse Discrete Zak Transform (IDZT) of X[m, k], the time-delay-time domain signal is obtained, and the signal model is shown in Figure 1 (b).

[0132]

[0133] where n = 0, 1,..., N-1, m = 0, 1,..., M-1;

[0134] 1.3) The time-delay-time domain signal is parallel-serial converted to obtain the discrete time domain signal s[q], as shown in Figure 1 (c).

[0135]

[0136] where q = m + nM;

[0137] 1.4) After digital-to-analog conversion of the time-delay-time domain signal s[q], the integrated transmission signal s(t) is obtained;

[0138] 1.5) The time-delay-Doppler jointly modulated radar-communication integrated signal with bandwidth B = 61.44 MHz and signal repetition period T = 4.3 ms is obtained according to the experimental parameters in Table 1.

[0139] It is assumed that the subcarrier spacing is much smaller than the carrier frequency, i.e., Δf << f c In this paper, a time-delay-Doppler channel with P targets (or paths) is considered, i.e.,

[0140]

[0141] In formula (3), h p , τ p , and v p represent the complex attenuation, time delay, and Doppler shift of the pth target (or path), respectively.

[0142] In the radar-communication integrated method based on time-delay-Doppler joint modulation, it is assumed that the time delay and Doppler shift are integer and fractional multiples of the time delay and Doppler resolution, respectively, i.e., where and are the integer parts of the time delay and Doppler, respectively, is the fractional part of the Doppler. Let n(t) represent the noise with an average power of σ 2 , so the received time-domain signal is as follows:

[0143] r(t) = ∫∫ h(τ, v) s(t - τ) e j2πνt dνdτ + n(t) (4)

[0144] where s(t) represents the baseband transmitted signal. The received signal r(t) is subjected to analog-to-digital (A / D), serial-to-parallel conversion, and discrete Zak transform (DZT), and the time-delay-Doppler domain received signal Y[m, k] can be obtained. In the case of integer time delay, fractional Doppler, and ignoring noise, the relationship between Y[m, k] and X[m, k] is as follows:

[0145]

[0146]

[0147] where,

[0148]

[0149]

[0150] In formula (5), P represents the number of paths, h p represents the gain of the pth path, and φp Indicates the initial phase. Let ψ represent the Doppler exponent and the time delay exponent of the p-th path in the time delay-Doppler domain, respectively. p [m] represents the phase shift caused by the Doppler frequency shift.

[0151] The modulation and demodulation block diagram of the integrated signal based on time-delay-Doppler joint modulation is as follows: Figure 2 As shown. Specifically, at the transmitting end, the integrated system combines the encoded and modulated communication symbols and radar signal data at the modulation end. After IDZT and D / A conversion, it is transmitted through the transmitter. Next, the receiving end extracts the communication signal, performs OTFS demodulation and decoding on the extracted signal to obtain the communication information. Simultaneously, the integrated signal is reflected by the target in the field to obtain the target echo. The receiving end extracts the radar signal from the echo, performs radar signal processing, and thus realizes the radar detection function.

[0152] Step 2. System Architecture Design

[0153] 2.1) It is not difficult to see that the delay measured by "OTFS" is the relative delay (the delay difference between the target signal and the direct signal), while the absolute delay is equal to the relative delay plus the main path delay. For communication, the main path is the direct wave, and the main path delay can be measured through a synchronization system.

[0154] 2.2) However, for monostation radars, a large number of guard intervals are required to obtain the "main path" delay (the absolute delay of the first target), which leads to a waste of resources. Therefore, monostation radars are not suitable for "OTFS" and a multistation system is proposed.

[0155] 2.3) This invention uses the time difference of arrival (TDOA) of signals to locate the target. Figure 3 This diagram illustrates the principle of elliptical positioning for two-dimensional target localization, where the target lies on an ellipse with the transmitting station and each receiving station as foci. For three-dimensional target localization, at least three ellipsoidal equations are required, and the intersection of these three ellipsoids represents the target's position. Therefore, the radar-communication integrated method of this invention operates in a "one-transmit, three-receive" mode.

[0156] 2.4) Design of an integrated radar-communication system based on time-delay-Doppler joint modulation, such as... Figure 4The system mainly includes an integrated signal transmitting station, a detection target and a user terminal (UE). In the downlink, the transmitting station transmits an integrated signal, and the UE receives the integrated signal and extracts a communication signal echo and a radar signal echo; in the uplink, the UE transmits target time delay and Doppler information obtained from the radar signal echo to the cloud to realize signal processing. Because the direction of the target is uncertain, the application considers adopting a "Y" type station arrangement. Because the "Y" type station positioning precision distribution is uniform and the positioning precision is high in the "one transmission and three reception" system, the "Y" type station arrangement is suitable for full airspace target detection. The position parameters of the transmitting station and the UE are shown in Table 2.

[0157] Table 2 Real position of transmitting station and UE

[0158]

[0159] Step 3. Integrated received signal processing

[0160] 3.1) The receiving end adopts a turbo iterative maximum ratio combining algorithm (MRC) to demodulate the communication data of the radar communication integrated signal, obtains original transmission information, and according to the relationship between the communication error rate and the signal-to-noise ratio as shown in Figure 7 , in order to meet the reliability of the communication system, the embodiment takes 10 -5 as the requirement, selects an environment with a signal-to-noise ratio of 26 dB to carry out integrated experiments, and the simulation scene contains three targets, and the position and speed parameters of the targets are shown in Table 3.

[0161] Table 3 Real position and speed of target

[0162]

[0163]

[0164] In this embodiment, the radar signal echo is separated from the integrated echo at the receiving end, as shown in Figure 8 . The cross-correlation method is adopted to estimate the time difference of arrival (TDOA) and Doppler of the target signal. In this section, the H i,j [m, k] and ζ N (k+κ) are cross-correlated to estimate the parameters of each target. The estimated parameters include: path gain (h p ), time delay Doppler phase shift (ψ p ) caused by Doppler frequency offset and initial phase (φ p ).

[0165] Specifically, this is achieved through the following steps 1) to 4):

[0166] 1) Assume the expression for the time-delay-Doppler domain radar signal is:

[0167]

[0168] Where k and m represent the Doppler and time delay index values ​​of the time delay-Doppler grid, respectively. i and j represent the time delay and Doppler grid index values ​​of the time delay-Doppler grid where the radar signal is located, respectively.

[0169] 2) The impulse response H of the radar signal i,j The expression for [m,k] is

[0170]

[0171] Where P represents the number of paths, h p Let ψ represent the gain of the p-th path. p [l] represents the phase shift caused by the Doppler frequency shift, φ p It is the initial phase. This represents the Doppler index of the p-th path in the delay-Doppler domain. This represents the delay exponent of the p-th path in the delay-Doppler domain.

[0172]

[0173] 3) Combine the radar signal impulse response with ζ N Interrelated

[0174]

[0175] 4) This invention considers the case of a single target in the l-th time delay grid, and the radar signal at m = Ml max In the time-delay Doppler domain, k = N / 2. D is the required resolution of the fractional Doppler κ, for example, D = 100 (interval 0.01). When estimating the Doppler index... The actual Doppler index of the p-th path The function reaches its maximum value when a match is found. Therefore, by finding about The maximum magnitude of the function can be used to estimate the target parameters of the l-th time-delay grid as follows:

[0176]

[0177] In a multi-objective scenario, the decision condition for stopping estimation of one object is:

[0178]

[0179] The process can be stopped if either of the above two conditions is met, where α is 1 / 50, β is 1 / 10, and σ is the noise standard deviation.

[0180] Therefore, the target time delay required for target location and velocity measurement can be obtained. Path gain h p and Doppler information.

[0181] 3.2) Based on the channel information (target delay) obtained in step 3.1) Path gain h p and Doppler The communication data is demodulated using MRC (Meaning-Responsive Cross-Meaning). MRC detection iteratively improves the signal-to-interference-plus-noise ratio (SINR) after MRC by eliminating the estimated inter-symbol vector interference in the selected delay branch. MRC detection has lower complexity in the delay-time domain; therefore, this paper chooses to demodulate the communication data in the delay-time domain. The channel response in the delay-time domain is:

[0182]

[0183] Channel response matrix in the delay-time domain for

[0184]

[0185] Defined at the i-th th The residual noise plus interference (RNPI) term in the next iteration is

[0186]

[0187] in, This refers to the residual error in reconstructing the received delay – the time-domain symbol – caused by estimation errors in the transmitted symbols. Symbolic vector It is estimated in ascending order of m = 0, ..., M-1.

[0188] i-th th The next iteration for

[0189]

[0190] in, It contains In all delay branches ( in The maximum ratio combination of RNPI. A * Denotes the complex conjugate of A. This indicates the multiplication of matrix elements.

[0191] i-thth The MRC output of the i-th iteration is

[0192]

[0193] where,

[0194]

[0195] In the above equation, denotes the division of matrix elements, denotes the Hermitian transpose of A.

[0196] In the i-th iteration, for each estimated symbol vector th The vector needs to be updated.

[0197]

[0198] When the overall RNPI error is no longer reduced, the MRC detection iteration stops. In one iteration, the overall complexity of M(2P+1)N complex multiplications is required to compute all symbol vectors and .

[0199] Finally, the estimated vector in the delay-time domain is transformed into the delay-Doppler domain by an N-point DFT (F N ), and the estimated value of the transmitted symbol vector x m is obtained.

[0200]

[0201] Considering the influence of noise, the c m (n) of each symbol is not necessarily exactly in the set of modulation symbols, so c m (n) needs to be processed by the following equation.

[0202]

[0203] In the equation, Q represents the set of modulation symbols used in the communication system (w = 1,..., |Q|, n = 0,..., N-1).

[0204] 3.3) The present application considers a three-dimensional positioning scenario of a target, as shown in Figure 6 There is one transmitting station, one target, and B (B = 3) UEs, where both the transmitting station and the UEs are in a stationary state. The true values of the position and velocity of the target to be positioned are denoted as u o = [x o , y​o z o ] T and The true position of the transmitting station is denoted by s The true values of the UE positions are denoted by s o The true values of the UE positions are denoted by s T denotes the transpose of a matrix.

[0205] However, in practice, the true positions of the transmitting stations and UEs are difficult to obtain, and only the observed values s t = [x t , y t , z t ] T and s r,b = [x r,b , y r,b , z r,b ] T (b = 1, 2, …, B), i.e.

[0206]

[0207] where Δs t and Δs r,b denote the station location errors of the transmitting stations and UEs, respectively. Define the following vectors:

[0208]

[0209]

[0210]

[0211] s = s o + Δs

[0212] where s is the position vector of the transmitting stations and UEs with errors, s o is the true position vector of the transmitting stations and UEs, and Δs is the position error vector of the transmitting stations and UEs. Assuming that Δs follows a Gaussian distribution with zero mean, the covariance matrix E[ΔsΔs T ] = Q s .

[0213] 1) According to Figure 6 , for the receiving end b, the positioning equation of the distance difference between the reflected path and the direct path and the rate of change of the distance difference can be expressed as:

[0214]

[0215]

[0216] where

[0217]

[0218]

[0219]

[0220]

[0221]

[0222] Considering that the estimation results of station site error and distance difference, distance difference rate are not completely accurate, only the positioning equation containing error can be obtained, that is:

[0223]

[0224]

[0225] The above formula is expressed in vector form:

[0226] r = r o + Δr

[0227]

[0228] Wherein,

[0229]

[0230]

[0231] Combining the above formula, the overall positioning equation is obtained:

[0232] α = α o + Δα

[0233] Wherein, represents the positioning parameter measurement vector, represents the true value vector of the positioning parameter, represents the positioning parameter measurement error vector, assuming that Δα obeys zero mean Gaussian distribution, then the covariance matrix of Δα is E[ΔαΔα T ] = Q α .

[0234] 2) The distance difference positioning equation can be expressed as:

[0235] R t + R r,b = r b,t + R t,r,b , (b = 1, 2, …, B) using Chan algorithm to solve the above formula, the target position coordinates u can be obtained.

[0236] The above equations are a set of nonlinear equations with respect to u, denoted as

[0237] Au = B

[0238] where

[0239]

[0240] P m = r m,t + R t,r,m ,

[0241] Q m = (P m 2 + x t 2 + y t 2 + z t 2 - x r,m 2 - y r,m 2 - z r,m 2 ) / 2, (m = 1, 2,...M)

[0242] In the case of selecting a proper station site, rank(A) = M, the equation set can be solved by using the pseudo-inverse method to obtain:

[0243] u = (A T A) -1 A T B = A -1 B

[0244] Let

[0245]

[0246] Since

[0247] ||u - s t || 2 = R t 2

[0248] Thus:

[0249] aR t 2 + 2bR t + c = 0

[0250] where,

[0251]

[0252]

[0253]

[0254] So,

[0255]

[0256] Substitute R t into B = Q - R t · P to find B, and then substitute B into Au = B to find the target position u.

[0257] 3) The distance difference rate positioning equation is expressed as:

[0258]

[0259] The matrix form is expressed as:

[0260]

[0261] In step 2), the positioning of the target is realized, i.e., the target position coordinate u is a known quantity; the radial velocity of the target is obtained through the Doppler Therefore, the above formula is a linear equation group with only unknowns. By solving the above formula, the moving speed of the target

[0262] 4) According to the above steps, the positioning and speed calculation of the target are performed, and the estimated position and speed of the target are shown in Table 4. By comparing Table 3 and Table 4, it can be seen that the estimated value of the target parameter is relatively small compared with the true value.

[0263] Table 4 Estimated position and speed of the target

[0264]

[0265]

[0266] 5) In order to comprehensively verify the positioning and speed performance of the method in three-dimensional space, Monte Carlo simulation experiments are performed in Figure 6 the scene. It is assumed that the position measurement errors of the transmitting station and the UE are not related, and are subject to a Gaussian distribution with a mean of 0 and a standard deviation of 0.5 m. The time errors of all UE echo signals are not related, and satisfy a Gaussian distribution with a mean of 0 and a standard deviation ranging from 0.1 ns to 20 ns. The Doppler frequency offset errors of different UEs are not related, and satisfy a Gaussian distribution with a mean of 0 and a standard deviation of 2.8 Hz. The root mean square error (RMSE) of 3000 times of Monte Carlo simulation is used to measure the radar detection performance. ​

[0267] The positioning and velocity measurement results of the target are shown in Figure 9 As can be seen from the figure, the RMSE of the positioning error and the velocity measurement error of the target are consistent with the CRLB.

[0268] The application provides a distributed radar-communication integrated method based on time-delay-Doppler joint modulation, and there are many methods and approaches for realizing the technical scheme, and the above description is only the preferred embodiment of the application, and it should be pointed out that, for ordinary skilled in the art, some improvements and refinements can be made without departing from the principle of the application, and these improvements and refinements should also be regarded as the protection scope of the application. The components not explicitly described in the embodiment can be realized by using the prior art.

[0269] Embodiment 2

[0270] In a second aspect, the embodiment provides a distributed radar-communication integrated device based on time-delay-Doppler joint modulation, comprising a processor and a storage medium.

[0271] The storage medium is used for storing instructions.

[0272] The processor is used for operating according to the instructions to perform the steps of the method according to embodiment 1.

[0273] Embodiment 3

[0274] In a third aspect, the embodiment provides a storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the method according to embodiment 1.

[0275] Embodiment 4

[0276] In a fourth aspect, the embodiment provides a computer device, comprising a processor and a storage medium.

[0277] The storage medium is used for storing instructions.

[0278] The processor is used for operating according to the instructions to perform the steps of the method according to embodiment 1.

[0279] Those skilled in the art should understand that the embodiments of the application can be provided as a method, a system, or a computer program product. Therefore, the application can be in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program code.

[0280] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart Figure 1 one or more functions specified in the flowchart or multiple flows and / or blocks. Figure 1 one or more functions specified in the flowchart or multiple flows and / or blocks.

[0281] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart Figure 1 one or more functions specified in the flowchart or multiple flows and / or blocks. Figure 1 one or more functions specified in the flowchart or multiple flows and / or blocks.

[0282] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart Figure 1 one or more functions specified in the flowchart or multiple flows and / or blocks. Figure 1 one or more functions specified in the flowchart or multiple flows and / or blocks.

[0283] The above only is the preferred embodiment of the present application, it should be pointed out that: for the ordinary skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A distributed radar communication integration method based on time delay-Doppler joint modulation, characterized in that, include: Step S1: In response to the transmitting station transmitting a radar-communication integrated signal based on time-delay-Doppler joint modulation, acquire the radar-communication integrated signal received by the receiving end. The radar-communication integrated signal consists of three parts: radar signal, communication signal, and guard interval. The construction process of the radar-communication integrated signal includes: S1.1, Protection Interval Length For the maximum delay spread in multipath, This indicates the protection interval caused by the target's maximum Doppler effect. This represents the additional protection interval due to fractional Doppler; the protection interval parameter in the Doppler dimension is equal to... The time-delay-Doppler domain signal is represented as The time-delay-Doppler domain signal consists of M subcarriers and N symbols. and These represent the Doppler and delay index exponents, respectively. S1.2, Delay-Doppler Domain Signal The time-delay-time domain signal is obtained by inverse discrete Zak transform. ; ； in , ; S1.3, Delay-Time Domain Signal Parallel-to-serial conversion yields discrete time-domain signals. ; ； in, ; S1.4 Discrete Time-Domain Signals After digital-to-analog conversion, the integrated radar and communication signal s(t) is obtained and used by the transmitting station for transmission; Step S2: Extract the communication signal echo and radar signal echo from the integrated radar and communication signal; obtain the target time delay, path gain and Doppler information based on the radar signal echo using the cross-correlation method; Step S3: Based on the target time delay, path gain and Doppler information, the turbo iterative maximum ratio merging algorithm is used to demodulate the communication signal echo to obtain the communication data in the time delay-Doppler domain grid. Step S4: Based on the target time delay and Doppler information, use the Chan method to locate and measure the velocity of the target, and obtain the target location and velocity measurement results.

2. The distributed radar-communication integrated method based on time-delay-Doppler joint modulation according to claim 1, characterized in that, In step S1, the radar-communication integration method is carried out in the "one transmit, three receive" mode.

3. The distributed radar-communication integrated method based on time-delay-Doppler joint modulation according to claim 1, characterized in that, In step S2, target time delay, path gain, and Doppler information are obtained using the cross-correlation method based on the radar signal echo, including: S2.1, Delay-Doppler Domain Radar Transmitted Signal The expression is: ； in , represents the Doppler and time delay index values ​​of the time delay-Doppler grid, respectively; i and j represent the time delay and Doppler grid index values ​​of the time delay-Doppler grid where the radar signal is located, respectively; S2.2, then the impulse response of the radar signal The expression is: ； Where P represents the number of paths. This represents the gain of the p-th path. This indicates the phase shift caused by the Doppler frequency shift. It is the initial phase. This represents the Doppler index of the p-th path in the delay-Doppler domain. The delay exponent represents the delay index of the p-th path in the delay-Doppler domain; ； S2.3, Radar signal pulse response With intermediate parameters By performing cross-correlation, we obtain the cross-correlation function. : ； Suppose there is a single target in the l-th time delay grid, and the radar signal is in , In the time-delay-Doppler domain; D is the required fractional Doppler value. The resolution; when estimating the Doppler index The actual Doppler index of the p-th path When matched, the cross-correlation function Reaching the maximum value, that is ;^ indicates an estimated value; S2.4, by finding the information about The maximum magnitude of the function is used to estimate the target parameters for the l-th time-delay grid. ； In a multi-objective scenario, the decision to stop estimating a target is to satisfy at least one of the following two conditions: ； in It is 1 / 50. It is 1 / 10. The standard deviation of noise; This yields the target time delay. Path gain and Doppler information.

4. The distributed radar-communication integrated method based on time delay-Doppler joint modulation according to claim 1, characterized in that, Step S3: Based on the target time delay, path gain, and Doppler information, the turbo iterative maximum ratio combining (MRC) algorithm is used to demodulate the communication signal echo to obtain the communication data in the time delay-Doppler domain grid; including: Delay-time domain channel response for: ； Where P represents the number of paths. This represents the gain of the p-th path. This represents the Doppler index of the p-th path in the delay-Doppler domain. The delay exponent represents the delay index of the p-th path in the delay-Doppler domain; Channel response matrix in the delay-time domain for: ； Defined in the The residual noise plus interference RNPI term in the next iteration is: ； in, This refers to the residual error in reconstructing the received delay – the time-domain symbol – caused by estimation errors in the transmitted symbols. symbol vector It is estimated in ascending order of m=0, ..., M-1; No. The next iteration for: ； in, It contains The combination of the maximum ratios of RNPI across all delay branches. ; Denotes the complex conjugate of A. This represents element-wise multiplication of matrices; No. MRC output of the next iteration for: ； in, ； In the above formula, This indicates that the matrix elements are divided. Represent the Hermitian transpose of A; In the In each iteration, for each estimated sign vector The vector needs to be updated. The latest estimated sign vector RNPI vector update is as follows: ； When the total RNPI error The MRC detection iteration stops when the number of signs no longer decreases; in one iteration, all symbol vectors are calculated. , and The overall complexity is Multiplication of complex numbers; Finally, the estimated vector in the time-delay domain is... The transmitted symbol vector is obtained by performing an N-point DFT transform into the time-delay Doppler domain. The estimated value; ； in This indicates an N-point DFT transformation; Each symbol is not necessarily exactly in the modulation symbol set. The data is processed to obtain the communication data in the time-delay-Doppler domain grid. : ； In the formula, Q represents the set of modulation symbols used in the communication system. Indicates modulation symbol, .

5. The distributed radar-communication integrated method based on time-delay-Doppler joint modulation according to claim 1, characterized in that, Step S4: Based on the target time delay, use the Chan method to locate and measure the velocity of the target, and obtain the target location and velocity measurement results, including: Consider a transmitting station, a target, and B = 3 user terminals (UEs), where the transmitting station and UEs are stationary. The true values ​​of the position and velocity of the target to be located are expressed as follows: and ; This represents the actual location of the launch station. Represents the actual location of the user terminal (UE); utilizing and Distinguish between the true value and the measured value of a variable. Represents the transpose of a matrix; In practice, the actual locations of the transmitting station and the user terminal (UE) are difficult to obtain; only measurement values ​​containing errors can be obtained. and ,Right now: (401)； In equation (401), , Let represent the site address errors of the transmitting station and each user terminal (UE), respectively; define the following vectors: (402)； In equation (402), This is a measurement vector containing the location of the transmitting station and the location of the user terminal (UE). It is a true vector containing the location of the transmitter station and the location of the user terminal (UE). This is the error vector between the transmitter location and the user terminal (UE) location; If it follows a Gaussian distribution with zero mean, then The covariance matrix is ; For receiver b, the positioning equations for the distance difference between the target's reflected path and its direct path, and the rate of change of that distance difference, are expressed as: (403)； in, (404); Considering that the estimates of site error, distance difference, and rate of change of distance difference cannot be completely accurate, only a positioning equation containing errors can be obtained, namely: (405) Equation (405) can be expressed in vector form as follows: (406)； in, (407)； Combining equation (406), we obtain the overall positioning equation as follows: (408)； in, This represents the measurement vector of positioning parameters. This represents the vector of true values ​​for the positioning parameters. This represents the positioning parameter measurement error vector, assuming... If it follows a Gaussian distribution with zero mean, then The covariance matrix is .

6. The distributed radar-communication integrated method based on time delay-Doppler joint modulation according to claim 5, characterized in that, Step S4: Based on the target time delay, use the Chan method to locate and measure the velocity of the target, and obtain the target location and velocity measurement results, including: Location equation based on distance difference Replace the parameters in the table with measured values, and rearrange the terms as follows: (409)； Based on target delay The distance difference between the target's reflection path and its direct path was calculated. The Chan algorithm is used to solve equation (409) to obtain the target position coordinates. ; Positioning equation for the rate of change of distance difference The parameters in the table are replaced with measured values, and are represented as follows: (410)； Its matrix form is: (411)； According to Doppler Obtain the radial velocity of the target Based on the target position coordinates obtained from the solution and the radial velocity of the target By solving equation (411), the target's moving speed can be obtained. .

7. A distributed radar-communication integrated device based on time-delay-Doppler joint modulation, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1 to 6.

8. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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