A frequency-phase parametric MIMO covert communication and sensing integrated signal generation and processing method

Abstract

The application discloses a frequency-phase parametric MIMO concealed communication and sensing integrated signal generation and processing method, which comprises the following steps: firstly, a continuous phase frequency hopping MIMO communication and sensing integrated transmitting waveform model is established; then, a frequency combination of communication information and a joint embedding mode of continuous phase modulation symbols are designed to generate a communication and sensing integrated transmitting signal with continuous phase between sub-pulses; then, a projection energy non-coherent demodulation method is designed at a communication receiving end to recover communication bits; meanwhile, a structure matching coherent processing method is designed at a radar receiving end to form a coarse distance-velocity-fine distance three-dimensional sensing response, and three-dimensional detection and target parameter estimation are performed. The method can simultaneously realize communication information transmission and radar target sensing under the same frequency hopping MIMO signal system, reduces spectrum leakage caused by phase hopping, improves the adaptability of communication reception to channel phase errors, suppresses distance grating caused by a discrete frequency aperture, and improves the separation and detection reliability of near distance strong and weak targets.

Description

Technical Field

[0001] This invention belongs to the field of signal processing technology, specifically relating to a method for generating and processing frequency phase-variable parametric MIMO covert sensing integrated signals. Background Technology

[0002] With the increasing demands for spectrum, RF front-end, and antenna resource sharing in wireless communication and radar sensing, radar-communication integration technology is gradually evolving from functional coexistence to waveform fusion. This technology utilizes the same transmitted signal to simultaneously complete target sensing and communication information transmission, improving the efficiency of spectrum and hardware resource utilization. Frequency-hopping multiple-input multiple-output radars switch between different frequencies using multiple transmitting elements, possessing multi-dimensional degrees of freedom in space, frequency, and time. This not only enhances the variability of transmitted signal parameters through frequency agility but also embeds communication information through frequency combinations, modulation symbols, and element allocation, thus demonstrating its potential for constructing covert integrated sensing signals.

[0003] Existing frequency-hopping MIMO integrated sensing methods typically utilize frequency-hopping codewords or frequency combinations to carry communication information. The literature "W. Baxter, E. Aboutanios and A. Hassanien, 'Joint radar and communications for frequency-hopped MIMO systems,' IEEE Transactions on Signal Processing, vol. 70, pp. 729-742, 2022" achieves communication information embedding by selecting different frequency combinations. This method can achieve communication transmission while maintaining radar sensing capabilities. However, when using only frequency combinations, the communication information carrying capacity is limited by the number of candidate frequencies and the number of transmitting array elements. Furthermore, when frequencies switch between adjacent sub-pulses, if the initial phases of different frequency components are not coordinated, phase jumps can easily occur at the sub-pulse boundaries, causing spectral spread and out-of-band leakage, affecting the signal's spectral constraint characteristics and covert transmission capabilities.

[0004] To improve the communication information carrying capacity of frequency-hopping MIMO signals, existing technologies further combine frequency selection with parameters such as phase modulation, element indexing, or element arrangement. The literature "J. Xu, X. Wang, E. Aboutanios and G. Cui, 'Hybrid index modulation for dual-functional radar communicationssystems,' IEEE Transactions on Vehicular Technology, vol. 72, no. 3, pp. 3186-3200, Mar. 2023" utilizes multi-dimensional resources such as frequency, phase, and element arrangement for communication information modulation. Multi-parameter joint modulation can expand the dimensions of communication information carrying capacity. However, phase information typically requires demodulation based on the propagation channel phase or array response phase. When the receiving end struggles to obtain accurate channel phase priors, or when there are estimation and calibration errors in the received phase corresponding to different transmitting elements, phase information decision-making is prone to mismatch, thus affecting the reliability of communication information recovery.

[0005] In radar sensing processing, target echoes in frequency-hopping MIMO signals on different frequency branches possess range phase and Doppler phase related to the carrier frequency. The literature "IP Eedara, MG Amin and GA Fabrizio, 'Target detection in frequency-hopping MIMO dual-function radar-communication systems,' Proc. IEEE International Conference on Acoustics, Speech and Signal Processing, Toronto, Canada, Jun. 2021, pp. 8458-8462" studies the target detection problem in frequency-hopping MIMO dual-function radar-communication systems. Existing processing typically separates or matches the frequency components and forms a range-velocity response based on this, but it does not fully utilize the phase correlation between echoes from different carrier frequencies. Since multiple discrete frequency components constitute a discontinuous frequency aperture, its range response is periodic. If the range phase and Doppler phase of different frequency branches are not consistently compensated, periodic range peaks or range gratings can easily form, causing the undesired response of strong targets to mask nearby weak targets, reducing the reliability of target separation, detection, and parameter estimation.

[0006] In summary, existing frequency-hopping MIMO integrated sensing technology has not yet fully resolved the coordination and matching issues between waveform generation, communication demodulation, and radar sensing processing. The main problems are: frequency switching may cause phase discontinuities and spectral leakage at the boundaries of adjacent sub-pulses; phase information recovery in multi-parameter modulation is highly dependent on accurate channel phase priors; and the carrier-frequency correlated phase structure of multi-frequency echoes is not fully utilized, easily leading to periodic range responses and range grating lobes. Therefore, how to maintain the phase continuity of frequency-hopping signals while improving communication information carrying capacity, how to reduce the dependence of communication demodulation on channel phase priors, and how to perform structural matching processing on multi-frequency target echoes are the technical problems that need to be solved in the generation and processing of covertly integrated sensing signals in frequency-hopping MIMO. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for generating and processing integrated frequency phase-change parametric MIMO covert sensing signals, which enables communication information transmission and radar target perception under the same frequency hopping MIMO waveform system.

[0008] The technical solution adopted in this invention is: a method for generating and processing frequency phase-change parametric MIMO covert sensing integrated signals, the specific steps of which are as follows:

[0009] S1. Construct a continuous phase frequency hopping MIMO integrated inductive transmission waveform model;

[0010] To construct a continuous phase frequency hopping MIMO integrated sensing transmission waveform model, the transmitter is first configured to use... One MIMO transmitter element, with a reference carrier frequency of Then the frequency offset set The expression is as follows:

[0011] ;

[0012] in, Indicates the number of candidate frequency offsets. , Indicates the first The frequency offset is set at equal intervals, as shown in the following expression:

[0013] ;

[0014] in, This indicates the initial frequency offset. This indicates the frequency offset interval between adjacent frequencies. The radio frequency carrier frequency corresponding to each frequency offset is The expression is as follows:

[0015] ;

[0016] For the The first launch element and the first The selected frequency offset and continuous phase modulation symbol for each sub-pulse are denoted as follows: and ,in:

[0017] ;

[0018] in, Represents the set of continuous phase modulation symbols. , This represents the m-th modulation symbol. , This indicates the number of continuous phase modulation symbols.

[0019] Then let , Construct the first The expression for the frequency-phase-variable parametric MIMO covert sensing integrated signal model of each transmitting array element is as follows:

[0020] ;

[0021] in, Indicates time, Indicates the first Continuous phase frequency hopping MIMO baseband transmission signal of each transmission element; Indicates continuous phase modulation components, This represents the frequency-hopping linear frequency modulation component.

[0022] The specific expression for the continuous phase modulation component is as follows:

[0023] ;

[0024] in,

[0025] ;

[0026] in, Indicates the continuous phase modulation index. This represents the number of sub-pulses within a single pulse. Indicates the first The first launch element in the... Continuous phase modulation symbols embedded within each sub-pulse Indicates the sub-pulse width. This represents the continuous phase modulation phase pulse function.

[0027] The specific expression for the frequency-hopping linear frequency modulation component is as follows:

[0028] ;

[0029] in, Indicates the first The rectangular time window corresponding to each sub-pulse Indicates the first The first launch element in the... The specific expressions for the frequency-hopping linear frequency modulation phase within each sub-pulse are as follows:

[0030] ;

[0031] ;

[0032] in, Indicates the first Local time within each sub-pulse Indicates the first The first launch element in the... Frequency offset selected within each sub-pulse Represents the linear frequency modulation slope, satisfying , Indicates the frequency modulation bandwidth within the sub-pulse; This indicates the frequency hopping linear frequency modulation phase compensation term.

[0033] Furthermore, the frequency hopping linear frequency modulation phase compensation term satisfies the following conditional expression:

[0034] ;

[0035] S2. Based on step S1, design a frequency combination and continuous phase modulation symbol joint embedding method for communication information to generate a transductive integrated transmission signal with continuous phase between sub-pulses.

[0036] First, a frequency combination codebook and a continuous phase modulation symbol codebook are constructed. Then, the communication bits are divided into frequency combination bit blocks and continuous phase modulation symbol bit blocks, and dictionary mapping is performed on each. Next, the ordered frequency combination codewords and continuous phase modulation symbol vectors are allocated through common permutation. Finally, a continuous phase frequency hopping MIMO inductive integrated transmission signal is generated based on the allocated frequency offset and continuous phase modulation symbols.

[0037] S3. Based on the integrated inductive transmission signal generated in step S2, design a projection energy incoherent demodulation method at the communication receiver to recover the communication bits;

[0038] First, a frequency-symbol joint template is constructed at the communication receiver. Based on the matching projection energy of the received subpulse and the candidate template, an incoherent demodulation criterion is established to realize frequency combination and symbol vector recovery without precise channel phase prior. Then, the communication bits are recovered based on dictionary inverse mapping.

[0039] S4. Based on the integrated sensing transmission signal generated in step S2, design a structure-matching coherent processing method at the radar receiver to form a coarse-range-velocity-fine-range three-dimensional sensing response, and perform three-dimensional detection and target parameter estimation.

[0040] First, the radar echo is processed by receiving beamforming and frequency branch downconversion. Then, a frequency branch baseband reference signal is constructed and frequency branch matched filtering is performed. Next, velocity-consistent Doppler focusing is performed on a unified physical velocity grid. Finally, based on the obtained range-velocity response matrices of each frequency branch, frequency aperture focusing is performed to form a coarse range-velocity-fine range three-dimensional sensing response, and three-dimensional detection and target parameter estimation are performed.

[0041] Furthermore, step S2 is specifically as follows:

[0042] S21. Construct a frequency combination codebook and a continuous phase modulation symbol codebook;

[0043] Based on step S1, frequency offset set The frequency is set at equal intervals, meaning that the offset between adjacent candidate frequencies satisfies... .

[0044] Then from the frequency offset set Selected from Each distinct frequency offset constitutes a frequency combination codeword, and the number of candidate frequency combinations is . Furthermore, the communication bits use a binary mapping, taking one of the bits... The candidate frequency combinations constitute the actual ordered frequency combination codebook, and the remaining candidate frequency combinations are reserved combinations.

[0045] in, This indicates the number of communication bits carried by the frequency combination, and The ordered frequency combination codebook The expression is as follows:

[0046] ;

[0047] in, Indicates the first A codeword with ordered frequency combinations, ; Indicates the first In the ordered frequency combination codeword, the first Each component in the frequency offset set The corresponding frequency index, And satisfy ; This indicates the transpose operation.

[0048] Then from the continuous phase modulation symbol set The continuous phase modulation symbol vector codebook is constructed as follows:

[0049] ;

[0050] in, Indicates the first A continuous phase modulation symbol vector codeword, ; Indicates the first In the nth continuous phase modulation symbol vector codeword Each component in the continuous phase modulation symbol set The corresponding symbol index in ; Represents a set of continuous phase modulation symbols Construction length is The set of continuous phase modulation symbol vectors; This represents the number of communication bits carried by the continuous phase modulation symbol vector, and .

[0051] S22. Divide the communication bits into frequency combination bit blocks and continuous phase modulation symbol bit blocks, and perform dictionary mapping for each;

[0052] The first The communication bits to be transmitted within each sub-pulse are divided into frequency combination bit blocks and continuous phase modulation symbol bit blocks, represented as follows: and And combine codebooks according to frequency Bit tag mapping function The frequency combination bit blocks are mapped to ordered frequency combination codewords based on the continuous phase modulation symbol vector codebook. Bit tag mapping function The expression for mapping a block of continuously phase modulated symbols (BMS) to a vector of continuously phase modulated symbols is as follows:

[0053] ;

[0054] in, The bit mapping function representing the frequency combination codebook, The bit mapping function represents the codebook of continuous phase modulation symbols. Indicates the first The ordered frequency combination codewords corresponding to each sub-pulse Indicates the first The continuous phase modulation symbol vector corresponding to each sub-pulse.

[0055] S23. Based on step S22, perform common permutation allocation on the ordered frequency combination codeword and the continuous phase modulation symbol vector;

[0056] Introducing the first The common permutation matrix corresponding to each sub-pulse The ordered frequency combination and continuous phase modulation symbol vector obtained in step S22 are synchronously permuted to obtain the frequency offset vector and continuous phase modulation symbol vector allocated to each MIMO transmitter element, as expressed below:

[0057] ;

[0058] in, Indicates the first The common permutation matrix corresponding to each sub-pulse This represents the frequency offset vector allocated to each MIMO transmitter element; This represents the continuous phase modulation symbol vector assigned to each MIMO transmitter element.

[0059] S24. Based on step S23, generate a continuous phase frequency hopping MIMO inductive integrated transmission signal according to the allocated frequency offset and continuous phase modulation symbols.

[0060] The result obtained in step S23 and Substituting the continuous phase frequency hopping MIMO integrated sensing transmit waveform model constructed in step S1, the first... Continuous phase frequency hopping MIMO baseband transmission signal of each transmitting element The transmitted signals from all the transmitting array elements constitute a synthetic integrated transmitted signal vector. The expression is as follows:

[0061] .

[0062] Furthermore, step S3 is specifically as follows:

[0063] First, after completing the sub-pulse timing synchronization at the communication receiving end, the first... The received signal segment corresponding to each subpulse is denoted as , .

[0064] in, Indicates sub-pulse width; received signal segment Including The first launch element in the... The result of the superposition of frequency-symbol components transmitted within each sub-pulse, as well as the communication reception noise.

[0065] Then, based on the frequency offset set in step S2 and continuous phase modulation symbol set Construct a frequency-symbol joint template for the th Candidate frequency offset and the Candidate continuous phase modulation symbols The corresponding local template The expression is as follows:

[0066] ;

[0067] in, Indicates the linear frequency modulation slope. Indicates the continuous phase modulation index. This represents the phase pulse function of continuous phase modulation. The number of frequency-symbol joint templates constructed is... .

[0068] Then the first The received signal segment of each sub-pulse The projection result is obtained by matching and projecting the result with the joint template of each frequency and symbol, as shown in the following expression:

[0069] ;

[0070] in, This indicates the conjugate operation.

[0071] Then, a projection energy table is established based on the squared magnitude of the projection result, as shown in the following expression:

[0072] ;

[0073] in, Indicates the first Subpulse at candidate frequency and candidate symbols Projected energy.

[0074] Based on the projected energy table, the energy of the continuous phase modulation symbol dimension corresponding to each candidate frequency is maximized to obtain the frequency energy statistics. The expression is as follows:

[0075] ;

[0076] Then, the ordered frequency combination codebook constructed in step S2 is further processed. Calculate the energy metric for each ordered frequency combination codeword one by one. Energy measurement of a frequency combination codeword The expression is as follows:

[0077] ;

[0078] in, Indicates the first The first sub-pulse Energy measure of an ordered frequency combination codeword; This indicates the codeword number. Frequency energy statistics corresponding to each frequency offset.

[0079] Then, frequency combination recovery is performed based on the energy metric of the frequency combination codewords. That is, among the ordered frequency combination codewords, the codeword with the largest energy metric is selected as the first codeword. The frequency combination recovery result of the sub-pulses is expressed as follows:

[0080] ;

[0081] in, Indicates the first The ordered frequency combination codeword index obtained by recovering each sub-pulse; This represents the recovered ordered frequency combination codeword; This indicates the first element in the recovered ordered frequency combination codeword. Each component in the frequency offset set The corresponding frequency index, .

[0082] Given the recovered frequency combination order, the energy metric of the candidate symbol vectors in the continuous phase modulation symbol vector codebook is calculated as follows:

[0083] ;

[0084] in, Indicates the first The first sub-pulse Energy metric of candidate continuous phase modulation symbol vector codewords .

[0085] Then, symbol vector recovery is performed based on the energy metric of the continuous phase modulation symbol vector. That is, among all continuous phase modulation symbol vector codewords, the codeword with the largest energy metric is selected as the first codeword. The expression for the recovery result of the continuous phase modulation symbol vector of each subpulse is as follows:

[0086] ;

[0087] in, Indicates the first Index of the continuous phase modulation symbol vector obtained from the recovery of each sub-pulse. This represents the recovered continuous phase modulation symbol vector;

[0088] The recovered frequency combination codeword and continuous phase modulation symbol vector are inversely mapped to obtain the first... The communication bits carried by each sub-pulse are expressed as follows:

[0089] ;

[0090] in, The inverse mapping function representing the frequency combination codebook, The inverse mapping function representing the continuous phase modulation symbol codebook, and These represent the recovered frequency combination bit block and the continuous phase modulation symbol bit block, respectively.

[0091] Ultimately, and Merge to obtain the first The communication bits recovered from each sub-pulse.

[0092] Furthermore, step S4 is specifically as follows:

[0093] S41. Perform receive beamforming and frequency branching downconversion processing on the radar received echo;

[0094] At the radar receiver, for continuous The echo signal of the first pulse is coherently processed. Then, the echo signal of the second pulse is processed coherently. The received echo of each pulse is used for receiving beamforming to obtain the received echo signal. and in accordance with the first Each frequency branch is down-converted to obtain the down-converted signal. The expression is as follows:

[0095] ;

[0096] in, , Indicates the number of coherent processing pulses. , Indicates the number of frequency branches. Indicates the first Frequency offset.

[0097] S42. Construct a frequency branch baseband reference signal and perform frequency branch matched filtering;

[0098] Based on the known continuous phase frequency hopping MIMO waveform, frequency allocation results, and array orientation assumptions at the transmitter, the first... The pulse, the first Each frequency branch under the angle assumption Directional transmission reference signal The directional transmission reference signal is processed into baseband to obtain the first... The baseband reference signal corresponding to each frequency branch The expression is as follows:

[0099] ;

[0100] The frequency branch echo signal obtained in step S41 The frequency branch matched response is obtained by performing matched filtering with the baseband reference signal. The expression is as follows:

[0101] ;

[0102] in, This represents the fine-distance delay variable.

[0103] For coarse distance delay mesh Calculate the matched filter output point by point to obtain the first... The pulse, the first Coarse-range matched response on each frequency branch , This indicates the coarse distance cell index.

[0104] S43. Perform velocity-consistent Doppler focusing on a uniform physical velocity grid;

[0105] Arrange the frequency branch matching responses obtained in step S42 according to the pulse sequence number to construct the first... Distance between frequency branches—slow-time response matrix The expression is as follows:

[0106] ;

[0107] in, Indicates the first The pulse, the first Coarse distance matched response of each frequency branch.

[0108] Then, velocity-consistent Doppler focusing is performed on a unified physical velocity grid, assuming the velocity search grid is... , No. Each frequency branch in speed The corresponding Doppler frequency The expression is as follows:

[0109] ;

[0110] in, To represent the speed of light, the unified physical velocity mesh expression is as follows:

[0111] ;

[0112] in,

[0113] ;

[0114] in, , Indicates the number of velocity grids. Indicates the velocity grid interval. This indicates the maximum unambiguous velocity that all frequency branches jointly satisfy. This indicates the pulse repetition period.

[0115] Based on the Doppler frequency, the first... Slow-time coherent focusing is performed on each frequency branch to obtain the range-velocity response matrix. The expression is as follows:

[0116] ;

[0117] in, Indicates the first Distance-velocity response matrix of each frequency branch, This indicates the coarse distance cell index.

[0118] S44. Based on the distance-velocity response matrices of each frequency branch obtained in step S43, frequency aperture focusing is performed to form a coarse distance-velocity-fine distance three-dimensional sensing response.

[0119] After completing velocity focusing for each frequency branch, fine-distance focusing is performed using discrete frequency apertures formed by different frequency branches. Each frequency branch in speed The equivalent frequency expression is as follows:

[0120] ;

[0121] in, This indicates the equivalent frequency used when performing frequency aperture focusing.

[0122] In fine-distance delay variables Below, in the finer distance dimension, phase compensation and coherent accumulation are performed on the distance-velocity response of each frequency branch to obtain the frequency aperture focusing output, as expressed below:

[0123] ;

[0124] in, Represents coarse distance cells Speed ​​unit and fine-distance delay variables The following is the focusing result;

[0125] Then in fine-distance delay mesh The above calculation of the frequency aperture focusing output yields the three-dimensional sensing response of coarse distance—velocity—fine distance, as expressed below:

[0126] ;

[0127] in, Indicates the number of fine-pitch grid cells; This indicates the total number of fine-pitch grid cells.

[0128] S45. Perform three-dimensional detection and target parameter estimation based on the coarse-range-velocity-fine-range three-dimensional sensing response obtained in step S44;

[0129] Based on the three-dimensional perception response obtained in step S44, a detection statistic is constructed. The expression is as follows:

[0130] ;

[0131] The detection statistics are subjected to threshold decision to obtain the target detection unit set, as shown in the following expression:

[0132] ;

[0133] in, Indicates the detection threshold. This represents the set of target detection units.

[0134] The detection threshold is determined using a preset threshold or a constant false alarm rate (CFAR) detection threshold, for local maximum units within the detection unit. According to its velocity unit index Obtain the target velocity estimate The expression is as follows:

[0135] ;

[0136] Based on fine-pitch units Obtain the fine distance estimate within the frequency aperture period. The expression is as follows:

[0137] ;

[0138] velocity unit The frequency-aperture distance period expression is as follows:

[0139] ;

[0140] in, Representing velocity unit The equivalent frequency interval between adjacent frequency branches is defined by the following expression:

[0141] ;

[0142] When the frequency branch meets the equal interval setting Sometimes, .

[0143] According to coarse distance unit Corresponding coarse distance center Determine the distance fuzzy branch number The expression is as follows:

[0144] ;

[0145] in, Represents the integer field. This represents the fuzzy branch number of the variable to be solved. The final target distance estimate. The expression is as follows:

[0146] .

[0147] The beneficial effects of this invention are as follows: First, the method of this invention establishes a transmit signal model that combines frequency combination selection, continuous phase modulation symbol embedding, and frequency hopping linear frequency modulation phase compensation. The communication information to be transmitted is mapped into frequency combination and continuous phase modulation symbol vectors, and distributed to multiple transmit array elements through common permutation to generate a MIMO integrated sensing transmit signal with constant envelope, frequency agility, and continuous phase between subpulses. Then, at the communication receiver, a frequency-symbol joint template is constructed, and an incoherent demodulation criterion is established based on the matching projection energy of the received subpulses and the candidate template, realizing frequency combination and symbol vector recovery without precise channel phase prior. At the radar receiver, based on the carrier frequency correlation phase structure of the multi-frequency echo, carrier frequency index joint matched filtering, velocity consistent Doppler focusing, and frequency aperture focusing are performed sequentially to form a coarse range-velocity-fine range three-dimensional sensing response for target detection and parameter estimation. The method of this invention can simultaneously realize communication information transmission and radar target perception under the same frequency-hopping MIMO signal system, reduce spectral leakage caused by phase jumps, improve the adaptability of communication receiver to channel phase errors, suppress range grating lobes caused by discrete frequency apertures, and improve the reliability of close-range strong and weak target separation and detection. It has high engineering feasibility and integrated sensing application value. The method of this invention embeds communication information by combining frequency combination and continuous phase modulation symbols, and uses frequency-hopping linear frequency modulation phase compensation to maintain phase continuity between sub-pulses; at the communication receiver, projection energy incoherent demodulation is used, which can recover communication bits without precise channel phase prior; at the radar receiver, structure-matched coherent processing is used to form a coarse range-velocity-fine range three-dimensional sensing response, suppress range grating lobes caused by discrete frequency apertures, and improve the reliability of target detection and parameter estimation. Attached Figure Description

[0148] Figure 1 This is a flowchart of a method for generating and processing frequency phase-variable parametric MIMO concealed sensing integrated signals according to the present invention.

[0149] Figure 2 This is a schematic diagram illustrating the dictionary mapping of communication information, the construction of standard frequency-phase, the antenna allocation, and the generation of continuous phase frequency hopping MIMO waveforms in an embodiment of the present invention.

[0150] Figure 3 This is a schematic diagram illustrating the frequency combination recovery, continuous phase modulation symbol vector recovery, and communication bit inverse mapping process based on the frequency-symbol joint template and projection energy table in an embodiment of the present invention.

[0151] Figure 4 This is a schematic diagram comparing the bit error rate performance of the method of the present invention with other frequency hopping MIMO communication embedding methods in an embodiment of the present invention.

[0152] Figure 5This is a schematic diagram of the radar sensing process based on structure matching coherent processing in an embodiment of the present invention.

[0153] Figure 6 This is a schematic diagram illustrating the performance analysis of radar target detection and parameter estimation using the structure-matching coherent processing method proposed in this embodiment of the invention. Detailed Implementation

[0154] The method of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0155] like Figure 1 The flowchart shown is a method for generating and processing frequency phase-change parametric MIMO covert sensing integrated signals according to the present invention. The specific steps are as follows:

[0156] S1. Construct a continuous phase frequency hopping MIMO integrated inductive transmission waveform model;

[0157] To construct a continuous phase frequency hopping MIMO integrated sensing transmission waveform model, the transmitter is first configured to use... One MIMO transmitter element, with a reference carrier frequency of Then the frequency offset set The expression is as follows:

[0158] ;

[0159] in, Indicates the number of candidate frequency offsets. In this embodiment , Indicates the first The frequency offset is set at equal intervals, as shown in the following expression:

[0160] ;

[0161] in, This indicates the initial frequency offset. This indicates the frequency offset interval between adjacent frequencies. The radio frequency carrier frequency corresponding to each frequency offset is The expression is as follows:

[0162] ;

[0163] For the The first launch element and the first The selected frequency offset and continuous phase modulation symbol for each sub-pulse are denoted as follows: and ,in:

[0164] ;

[0165] in, Represents the set of continuous phase modulation symbols. In this embodiment , This represents the m-th modulation symbol. , This indicates the number of continuous phase modulation symbols.

[0166] To ensure that different transmitting array elements occupy different frequency offsets within the same sub-pulse, let , Construct the first The expression for the frequency-phase-variable parametric MIMO covert sensing integrated signal model of each transmitting array element is as follows:

[0167] ;

[0168] in, Indicates time, Indicates the first Continuous phase frequency hopping MIMO baseband transmission signal of each transmission element; Indicates continuous phase modulation components, This represents the frequency-hopping linear frequency modulation component.

[0169] The specific expression for the continuous phase modulation component is as follows:

[0170] ;

[0171] in,

[0172] ;

[0173] in, Indicates the continuous phase modulation index. This represents the number of sub-pulses within a single pulse. Indicates the first The first launch element in the... Continuous phase modulation symbols embedded within each sub-pulse Indicates the sub-pulse width. This represents the continuous phase modulation phase pulse function. In this embodiment, a rectangular full-response continuous phase modulation phase pulse function is used, and its expression is as follows:

[0174] ;

[0175] The specific expression for the frequency-hopping linear frequency modulation component is as follows:

[0176] ;

[0177] in, Indicates the first The rectangular time window corresponding to each sub-pulse Indicates the first The first launch element in the... The specific expressions for the frequency-hopping linear frequency modulation phase within each sub-pulse are as follows:

[0178] ;

[0179] ;

[0180] in, Indicates the first Local time within each sub-pulse Indicates the first The first launch element in the... Frequency offset selected within each sub-pulse Represents the linear frequency modulation slope, satisfying , Indicates the frequency modulation bandwidth within the sub-pulse; This indicates the frequency hopping linear frequency modulation phase compensation term.

[0181] Furthermore, the frequency hopping linear frequency modulation phase compensation term satisfies the following conditional expression:

[0182] ;

[0183] S2. Based on step S1, design a frequency combination and continuous phase modulation symbol joint embedding method for communication information to generate a transductive integrated transmission signal with continuous phase between sub-pulses.

[0184] First, a frequency combination codebook and a continuous phase modulation symbol codebook are constructed. Then, the communication bits are divided into frequency combination bit blocks and continuous phase modulation symbol bit blocks, and dictionary mapping is performed on each. Next, the ordered frequency combination codewords and continuous phase modulation symbol vectors are allocated through common permutation. Finally, a continuous phase frequency hopping MIMO inductive integrated transmission signal is generated based on the allocated frequency offset and continuous phase modulation symbols.

[0185] S3. Based on the integrated inductive transmission signal generated in step S2, design a projection energy incoherent demodulation method at the communication receiver to recover the communication bits;

[0186] First, a frequency-symbol joint template is constructed at the communication receiver. Based on the matching projection energy of the received subpulse and the candidate template, an incoherent demodulation criterion is established to realize frequency combination and symbol vector recovery without precise channel phase prior. Then, the communication bits are recovered based on dictionary inverse mapping.

[0187] S4. Based on the integrated sensing transmission signal generated in step S2, design a structure-matching coherent processing method at the radar receiver to form a coarse-range-velocity-fine-range three-dimensional sensing response, and perform three-dimensional detection and target parameter estimation.

[0188] First, the radar echo is processed by receiving beamforming and frequency branch downconversion. Then, a frequency branch baseband reference signal is constructed and frequency branch matched filtering is performed. Next, velocity-consistent Doppler focusing is performed on a unified physical velocity grid. Finally, based on the obtained range-velocity response matrices of each frequency branch, frequency aperture focusing is performed to form a coarse range-velocity-fine range three-dimensional sensing response, and three-dimensional detection and target parameter estimation are performed.

[0189] like Figure 2 As shown, in this embodiment, step S2 is specifically as follows:

[0190] S21. Construct a frequency combination codebook and a continuous phase modulation symbol codebook;

[0191] In this embodiment, the frequency offset set is specifically as follows: Based on step S1, the frequency offset set The frequency is set at equal intervals, meaning that the offset between adjacent candidate frequencies satisfies... .

[0192] In this embodiment, the number of MIMO transmitter array elements is: Therefore, each sub-pulse selects four distinct frequency offsets from the eight candidate frequency offsets to form a frequency combination codeword. The number of candidate frequency combinations is... Furthermore, the communication bits use a binary mapping, taking one of the bits... The candidate frequency combinations constitute the actual ordered frequency combination codebook, and the remaining candidate frequency combinations are reserved combinations.

[0193] in, This indicates the number of communication bits carried by the frequency combination, and The ordered frequency combination codebook The expression is as follows:

[0194] ;

[0195] in, Indicates the first A codeword with ordered frequency combinations, ; Indicates the first In the ordered frequency combination codeword, the first Each component in the frequency offset set The corresponding frequency index, And satisfy ; This indicates a transpose operation. In this embodiment... And satisfy In this embodiment, each ordered frequency combination codeword corresponds to a 6-bit frequency combination selection tag, so each sub-pulse carries 6 bits of communication information through frequency combination selection.

[0196] Then from the continuous phase modulation symbol set The continuous phase modulation symbol vector codebook is constructed as follows:

[0197] ;

[0198] in, Indicates the first A continuous phase modulation symbol vector codeword, ; Indicates the first In the nth continuous phase modulation symbol vector codeword Each component in the continuous phase modulation symbol set The corresponding symbol index in , ; Represents a set of continuous phase modulation symbols Construction length is The set of continuous phase modulation symbol vectors; This represents the number of communication bits carried by the continuous phase modulation symbol vector, and .

[0199] In this embodiment, each continuous phase modulation symbol vector codeword corresponds to an 8-bit phase vector selection tag, so each sub-pulse carries 8 bits of communication information through the continuous phase modulation symbol vector.

[0200] S22. Divide the communication bits into frequency combination bit blocks and continuous phase modulation symbol bit blocks, and perform dictionary mapping for each;

[0201] The first The communication bits to be transmitted within each sub-pulse are divided into frequency combination bit blocks and continuous phase modulation symbol bit blocks, represented as follows: and And combine codebooks according to frequency Bit tag mapping function The frequency combination bit blocks are mapped to ordered frequency combination codewords based on the continuous phase modulation symbol vector codebook. Bit tag mapping function The expression for mapping a block of continuously phase modulated symbols (BMS) to a vector of continuously phase modulated symbols is as follows:

[0202] ;

[0203] in, The bit mapping function representing the frequency combination codebook, The bit mapping function represents the codebook of continuous phase modulation symbols. Indicates the first The ordered frequency combination codewords corresponding to each sub-pulse Indicates the first The continuous phase modulation symbol vector corresponding to each sub-pulse.

[0204] Therefore, the first The communication bits to be transmitted within each sub-pulse are mapped to a set of ordered frequency combinations. and a set of continuous phase modulation symbol vectors Among them, the ordered frequency combination is used to determine the frequency offset occupied within the sub-pulse, and the continuous phase modulation symbol vector is used to determine the continuous phase modulation symbol embedded within the sub-pulse.

[0205] S23. Based on step S22, perform common permutation allocation on the ordered frequency combination codeword and the continuous phase modulation symbol vector;

[0206] Introducing the first The common permutation matrix corresponding to each sub-pulse The ordered frequency combination and continuous phase modulation symbol vector obtained in step S22 are synchronously permuted to obtain the frequency offset vector and continuous phase modulation symbol vector allocated to each MIMO transmitter element, as expressed below:

[0207] ;

[0208] in, Indicates the first The common permutation matrix corresponding to each sub-pulse This represents the frequency offset vector allocated to the four MIMO transmit elements; This represents the continuous phase modulation symbol vector assigned to each MIMO transmitter element.

[0209] The common permutation matrix It simultaneously acts on ordered frequency combinations and continuous phase modulation symbol vectors to maintain the pairing relationship between frequency offset and continuous phase modulation symbols. That is, after a common permutation, the frequency offset and continuous phase modulation symbol of the frequency-symbol pairing unit formed under the canonical order are still assigned to the same transmit array element as the same pairing unit.

[0210] S24. Based on step S23, generate a continuous phase frequency hopping MIMO inductive integrated transmission signal according to the allocated frequency offset and continuous phase modulation symbols.

[0211] The result obtained in step S23 and Substituting the continuous phase frequency hopping MIMO integrated sensing transmit waveform model constructed in step S1, the first... Continuous phase frequency hopping MIMO baseband transmission signal of each transmitting element The transmitted signals from all the transmitting array elements constitute a synthetic integrated transmitted signal vector. The expression is as follows:

[0212] ;

[0213] In this embodiment, each sub-pulse carries 6 bits through frequency combination and 8 bits through continuous phase modulation of the symbol vector, therefore each sub-pulse carries a total of 14 communication bits. Since each pulse contains... There are 10 sub-pulses, therefore each pulse can carry 100 communication bits. .

[0214] like Figure 3 As shown, in this embodiment, step S3 is specifically as follows:

[0215] First, after completing the sub-pulse timing synchronization at the communication receiving end, the first... The received signal segment corresponding to each subpulse is denoted as , .

[0216] in, Indicates sub-pulse width; received signal segment Including The first launch element in the... The result of the superposition of frequency-symbol components transmitted within each sub-pulse, as well as the communication reception noise.

[0217] Then, based on the frequency offset set in step S2 and continuous phase modulation symbol set Construct a frequency-symbol joint template for the th Candidate frequency offset and the Candidate continuous phase modulation symbols The corresponding local template The expression is as follows:

[0218] ;

[0219] in, Indicates the linear frequency modulation slope. Indicates the continuous phase modulation index. This represents the phase pulse function of continuous phase modulation. The number of frequency-symbol joint templates constructed is... .

[0220] Then the first The received signal segment of each sub-pulse The projection result is obtained by matching and projecting the image with a joint template of 32 frequencies and symbols, as shown in the following expression:

[0221] ;

[0222] in, This represents the conjugate operation. In this embodiment, the projected energy table is... The table is a 3D table, where each row corresponds to a candidate frequency offset and each column corresponds to a candidate continuous phase modulation symbol.

[0223] Then, a projection energy table is established based on the squared magnitude of the projection result, as shown in the following expression:

[0224] ;

[0225] in, Indicates the first Subpulse at candidate frequency and candidate symbols Projected energy.

[0226] Based on the projected energy table, the energy of the continuous phase modulation symbol dimension corresponding to each candidate frequency is maximized to obtain the frequency energy statistics. (This process is used to determine whether each candidate frequency is actually occupied by the current sub-pulse when the continuous phase modulation symbols are unknown.) The expression is as follows:

[0227] ;

[0228] Then, the ordered frequency combination codebook constructed in step S2 is further processed. Calculate the energy metric for each ordered frequency combination codeword one by one. Energy measurement of a frequency combination codeword The expression is as follows:

[0229] ;

[0230] in, Indicates the first The first sub-pulse Energy measure of an ordered frequency combination codeword; This indicates the codeword number. Frequency energy statistics corresponding to each frequency offset.

[0231] Then, frequency combination recovery is performed based on the energy metric of the frequency combination codewords. That is, among the ordered frequency combination codewords, the codeword with the largest energy metric is selected as the first codeword. The frequency combination recovery result of the sub-pulses is expressed as follows:

[0232] ;

[0233] in, Indicates the first The ordered frequency combination codeword index obtained by recovering each sub-pulse; This represents the recovered ordered frequency combination codeword; This indicates the first element in the recovered ordered frequency combination codeword. Each component in the frequency offset set The corresponding frequency index, .

[0234] Given the recovered frequency combination order, the energy metric of the candidate symbol vectors in the continuous phase modulation symbol vector codebook is calculated as follows:

[0235] ;

[0236] in, Indicates the first The first sub-pulse Energy metric of candidate continuous phase modulation symbol vector codewords , Indicates the first In the nth symbol vector codeword The symbol index corresponding to each continuous phase modulation symbol.

[0237] Then, symbol vector recovery is performed based on the energy metric of the continuous phase modulation symbol vector. That is, among all continuous phase modulation symbol vector codewords, the codeword with the largest energy metric is selected as the first codeword. The expression for the recovery result of the continuous phase modulation symbol vector of each subpulse is as follows:

[0238] ;

[0239] in, Indicates the first Index of the continuous phase modulation symbol vector obtained from the recovery of each sub-pulse. This represents the recovered continuous phase modulation symbol vector;

[0240] The recovered frequency combination codeword and continuous phase modulation symbol vector are inversely mapped to obtain the first... The communication bits carried by each sub-pulse are expressed as follows:

[0241] ;

[0242] in, The inverse mapping function representing the frequency combination codebook, The inverse mapping function representing the continuous phase modulation symbol codebook, and These represent the recovered frequency combination bit block and the continuous phase modulation symbol bit block, respectively.

[0243] Ultimately, and Merge to obtain the first The communication bits recovered from each sub-pulse.

[0244] Therefore, this embodiment uses a projected energy meter. In the amplitude domain, incoherent demodulation is performed by first recovering the frequency combination using frequency energy statistics, and then recovering the continuous phase modulation symbol vector in the order of the recovered frequency combination. Since this method uses the square of the amplitude of the projection result for decision-making, it does not require coherent phase merging of different transmit array element components. Therefore, it can complete the recovery of frequency combination and continuous phase modulation symbol vector without precise channel phase prior.

[0245] In this embodiment, to verify the communication performance of the projected energy incoherent demodulation method, the bit error rate performance of the method of the present invention is compared with that of Frequency-Hopping Phase-Shift Keying (FH-PSK), Frequency-Hopping Code Selection (FHCS), Frequency Hopping Selection and Permutation (FHSP), PSK over Code Selection (POCS), and Hybrid Index Modulation (HIM). The comparison curves are shown below. Figure 4 As shown.

[0246] Figure 4 This diagram illustrates a comparison of the bit error rate performance of the method of this invention with the aforementioned typical frequency-hopping MIMO communication embedding methods. The horizontal axis represents the signal-to-noise ratio (SNR), and the vertical axis represents the bit error rate (BER). The "continuous phase frequency-hopping MIMO waveform" in the diagram represents the continuous phase frequency-hopping MIMO communication method of this invention using projected energy incoherent demodulation. Figure 4As can be seen, the bit error rate of the method of this invention gradually decreases with the increase of the signal-to-noise ratio, enabling reliable communication bit recovery. Compared with phase-based communication embedding methods that require precise channel phase priors, the method of this invention establishes a decision criterion based on the amplitude square of the matched projection result, eliminating the need for coherent phase combining of different transmit array element components. Therefore, it can complete the recovery of frequency combination and continuous phase modulation symbol vectors without requiring precise channel phase priors. This result demonstrates that the projection energy incoherent demodulation method described in step S3 can improve the adaptability of the communication receiver to channel phase errors while maintaining the joint carrying capacity of frequency combination and continuous phase modulation symbols.

[0247] like Figure 5 As shown, in this embodiment, step S4 is specifically as follows:

[0248] S41. Perform receive beamforming and frequency branching downconversion processing on the radar received echo;

[0249] At the radar receiver, for continuous The echo signal of the first pulse is coherently processed. Then, the echo signal of the second pulse is processed coherently. The received echo of each pulse is used for receiving beamforming to obtain the received echo signal. and in accordance with the first Each frequency branch is down-converted to obtain the down-converted signal. The expression is as follows:

[0250] ;

[0251] in, , Indicates the number of coherent processing pulses. , Indicates the number of frequency branches. Indicates the first The frequency offset is specified. In this embodiment, the target to be detected is located at approximately 2000 m, and the target radial velocity is approximately 20 m / s. Through step S41, the received echo containing multi-frequency components can be decomposed into different frequency branches, providing branched input for subsequent matched filtering and frequency aperture focusing.

[0252] S42. Construct a frequency branch baseband reference signal and perform frequency branch matched filtering;

[0253] Based on the known continuous phase frequency hopping MIMO waveform, frequency allocation results, and array orientation assumptions at the transmitter, the first... The pulse, the first Each frequency branch under the angle assumption Directional transmission reference signal The directional transmission reference signal is processed into baseband to obtain the first... The baseband reference signal corresponding to each frequency branch The expression is as follows:

[0254] ;

[0255] The frequency branch echo signal obtained in step S41 The frequency branch matched response is obtained by performing matched filtering with the baseband reference signal. The expression is as follows:

[0256] ;

[0257] in, This represents the fine-distance delay variable.

[0258] For coarse distance delay mesh Calculate the matched filter output point by point to obtain the first... The pulse, the first Coarse-range matched response on each frequency branch , This indicates the coarse distance cell index.

[0259] Step S42 uses the known continuous phase frequency hopping MIMO transmit structure to construct a matching reference signal, so that the frequency branch echo can achieve coherent compression in the coarse distance dimension and retain the carrier frequency related phase relationship between different frequency branches.

[0260] S43. Perform velocity-consistent Doppler focusing on a uniform physical velocity grid;

[0261] Arrange the frequency branch matching responses obtained in step S42 according to the pulse sequence number to construct the first... Distance between frequency branches—slow-time response matrix The expression is as follows:

[0262] ;

[0263] in, Indicates the first The pulse, the first Coarse-range matched response of each frequency branch;

[0264] Due to different frequency branches of radio frequency carrier frequencies Unlike other methods, the Doppler frequencies corresponding to the same target velocity are not exactly the same across different frequency branches. Therefore, this embodiment does not directly process the velocity on a unified Doppler frequency grid, but instead performs velocity-consistent focusing on a unified physical velocity grid. Let the velocity search grid be... , No. Each frequency branch in speed The corresponding Doppler frequency The expression is as follows:

[0265] ;

[0266] in, To represent the speed of light, the unified physical velocity mesh expression is as follows:

[0267] ;

[0268] in,

[0269] ;

[0270] in, , Indicates the number of velocity grids. Indicates the velocity grid interval. This indicates the maximum unambiguous velocity that all frequency branches jointly satisfy. Indicates the pulse repetition period;

[0271] Based on the Doppler frequency, the first... Slow-time coherent focusing is performed on each frequency branch to obtain the range-velocity response matrix. The expression is as follows:

[0272] ;

[0273] in, Indicates the first Distance-velocity response matrix of each frequency branch, This indicates the coarse distance cell index.

[0274] By using the above-mentioned velocity-consistent Doppler focusing, the slow-time phase of the same physical velocity target on different frequency branches is compensated according to its corresponding carrier frequency, thus avoiding Doppler focusing mismatch caused by different carrier frequencies in the frequency branches.

[0275] S44. Based on the distance-velocity response matrices of each frequency branch obtained in step S43, frequency aperture focusing is performed to form a coarse distance-velocity-fine distance three-dimensional sensing response.

[0276] After completing velocity focusing for each frequency branch, fine-distance focusing is performed using discrete frequency apertures formed by different frequency branches. Each frequency branch in speed The equivalent frequency expression is as follows:

[0277] ;

[0278] in, This indicates the equivalent frequency used when performing frequency aperture focusing.

[0279] In fine-distance delay variables Below, in the finer distance dimension, phase compensation and coherent accumulation are performed on the distance-velocity response of each frequency branch to obtain the frequency aperture focusing output, as expressed below:

[0280] ;

[0281] in, Represents coarse distance cells Speed ​​unit and fine-distance delay variables The following is the focusing result;

[0282] Then in fine-distance delay mesh The above calculation of the frequency aperture focusing output yields the three-dimensional sensing response of coarse distance—velocity—fine distance, as expressed below:

[0283] ;

[0284] in, Indicates the number of fine-pitch grid cells; This indicates the total number of fine-pitch grid cells.

[0285] In this embodiment, for low-speed targets, there are At this time, the frequency aperture distance period is approximately Within each coarse-range cell, by focusing the fine-range delay grid with a frequency aperture, a fine-range response can be obtained within the frequency aperture period, thereby extending the traditional coarse-range-velocity response into a three-dimensional coarse-range-velocity-fine-range response.

[0286] S45. Perform three-dimensional detection and target parameter estimation based on the coarse-range-velocity-fine-range three-dimensional sensing response obtained in step S44;

[0287] Based on the three-dimensional perception response obtained in step S44, a detection statistic is constructed. The expression is as follows:

[0288] ;

[0289] The detection statistics are subjected to threshold decision to obtain the target detection unit set, as shown in the following expression:

[0290] ;

[0291] in, Indicates the detection threshold. This represents the set of target detection units.

[0292] The detection threshold is determined using a preset threshold or a constant false alarm rate (CFAR) detection threshold, for local maximum units within the detection unit. According to its velocity unit index Obtain the target velocity estimate The expression is as follows:

[0293] ;

[0294] Based on fine-pitch units Obtain the fine distance estimate within the frequency aperture period. The expression is as follows:

[0295] ;

[0296] velocity unit The frequency-aperture distance period expression is as follows:

[0297] ;

[0298] in, Representing velocity unit The equivalent frequency interval between adjacent frequency branches is defined by the following expression:

[0299] ;

[0300] When the frequency branch meets the equal interval setting Sometimes, For the target shown in Figure 6, the structure-matching coherent processing is performed at a target distance of approximately... A peak response is formed at this point. In this embodiment, the adjacent frequency offset interval is... The target speed is estimated to be approximately Therefore, the equivalent frequency interval between adjacent frequency branches is .

[0301] According to coarse distance unit Corresponding coarse distance center Determine the distance fuzzy branch number The expression is as follows:

[0302] ;

[0303] in, Represents the integer field. This represents the variable to be solved, indicating the fuzzy branch index of the distance. In this embodiment, the final distance corresponding to the peak value of the coarse distance target is approximately... Based on the frequency aperture distance period calculation described above, the distance ambiguity branch number is taken as... The corresponding fine distance estimate within the period is .

[0304] Final target distance estimate The expression is as follows:

[0305] ;

[0306] In this embodiment, substitution , and ,get .

[0307] Figure 6 The radar target detection and parameter estimation results of the method of this invention are presented. Figure 6 (a) is a slice of the coarse-range normalized response at the target velocity element. Figure 6 (b) is a slice of the velocity-dimensional normalized response at the coarse-range cell of the target. Figure 6 (c) is a slice of the fine-range normalized response at the coarse-range-velocity cell of the target. Figure 6 (d) represents the coarse distance-velocity two-dimensional response processed in the traditional way. Figure 6 (e) is the coarse two-dimensional range-velocity response of the structure-matched coherent processing of the present invention. Figure 6 (f) represents the coarse-range to fine-range two-dimensional response of the structure-matching coherent processing of this invention. Figure 6 (a) It can be seen that traditional processing exhibits multiple periodic grating lobe responses caused by discrete frequency apertures in the coarse range dimension, which easily lead to additional peaks; in contrast, the structure-matched coherent processing described in this invention can effectively suppress the aforementioned range grating lobes and concentrate the target response near the true range. Figure 6 (b) It can be seen that after velocity-consistent Doppler focusing, the method of the present invention can form a concentrated response near the true velocity of the target, thus maintaining an accurate target velocity estimate. Figure 6 (c) Further, it is shown that after focusing by the frequency aperture, a narrow main lobe response can be formed within the frequency aperture period, and the 3 dB width in the fine distance dimension is about 1.6685 m, thereby improving the separation capability of close-range targets. Figure 6 (d) and Figure 6 (e) shows that the method of the present invention performs coherent matching of the carrier frequency-related phase structure of multi-frequency echoes by using velocity-consistent Doppler focusing and frequency aperture focusing. Compared with traditional processing, it can reduce the undesired peak caused by range grating lobes and concentrate the target energy at the coarse range-velocity position corresponding to the real target. Figure 6(f) Further, it is shown that after frequency aperture focusing, the target energy can be concentrated at the coarse-to-fine range position corresponding to the real target. In summary, the structure-matched coherent processing described in this invention can suppress the range grating lobe caused by discrete frequency apertures and obtain fine-range resolution while maintaining velocity focusing capability, thereby improving the reliability of target detection and range and velocity parameter estimation.

[0308] In summary, the method of this invention, under the same continuous-phase frequency-hopping MIMO waveform system, combines frequency combination selection, continuous-phase modulation symbol embedding, and frequency-hopping linear frequency modulation phase compensation to generate a constant envelope, frequency-agile, and inter-pulse phase continuous integrated sensing transmission signal. The communication receiver constructs a matched projection energy table based on a frequency-symbol joint template, sequentially recovering the frequency combination and continuous-phase modulation symbol vectors, achieving communication bit recovery without precise channel phase priors. The radar receiver utilizes the carrier-frequency correlated phase structure of the multi-frequency echo, sequentially performing frequency branch matched filtering, velocity-consistent Doppler focusing, and frequency aperture focusing to form a coarse-range-velocity-fine-range three-dimensional sensing response, and completes target detection and parameter estimation. This invention can balance communication information transmission and radar target perception within a unified waveform framework, effectively reducing spectral leakage caused by inter-pulse phase jumps, improving the adaptability of the communication receiver to channel phase errors, suppressing range grating lobes caused by discrete frequency apertures, and improving the reliability of close-range strong and weak target separation and detection. It possesses high feasibility in engineering implementation and integrated sensing application value.

[0309] Those skilled in the art should understand that the above embodiments are only used to illustrate the technical principles and implementation methods of the present invention, and are not intended to limit the scope of protection of the present invention. Any equivalent substitutions, modifications, or combinations made based on the technical concept disclosed in this invention regarding the continuous phase frequency hopping MIMO transmit waveform, communication information mapping method, projection energy demodulation criterion, structure matching coherent processing flow, or related parameter settings should fall within the scope of protection of this invention.

Claims

1. A method for generating and processing frequency phase-variable parametric MIMO concealed sensing integrated signals, the specific steps of which are as follows: S1. Construct a continuous phase frequency hopping MIMO integrated inductive transmission waveform model; To construct a continuous phase frequency hopping MIMO integrated sensing transmission waveform model, the transmitter is first configured to use... One MIMO transmitter element, with a reference carrier frequency of Then the frequency offset set The expression is as follows: ； in, Indicates the number of candidate frequency offsets. , Indicates the first The frequency offset is set at equal intervals, as shown in the following expression: ； in, This indicates the initial frequency offset. Indicates the frequency offset interval between adjacent frequencies; the first The radio frequency carrier frequency corresponding to each frequency offset is The expression is as follows: ； For the The first launch element and the first The selected frequency offset and continuous phase modulation symbol for each sub-pulse are denoted as follows: and ,in: ； in, Represents the set of continuous phase modulation symbols. , This represents the m-th modulation symbol. , Indicates the number of consecutive phase modulation symbols; Then let , Construct the first The expression for the frequency-phase-variable parametric MIMO covert sensing integrated signal model of each transmitting array element is as follows: ； in, Indicates time, Indicates the first Continuous phase frequency hopping MIMO baseband transmission signal of each transmission element; Indicates continuous phase modulation components, Indicates the frequency-hopping linear frequency modulation component; The specific expression for the continuous phase modulation component is as follows: ； in, ； in, Indicates the continuous phase modulation index. This represents the number of sub-pulses within a single pulse. Indicates the first The first launch element in the... Continuous phase modulation symbols embedded within each sub-pulse Indicates the sub-pulse width. This represents a continuous phase modulation phase pulse function; The specific expression for the frequency-hopping linear frequency modulation component is as follows: ； in, Indicates the first The rectangular time window corresponding to each sub-pulse Indicates the first The first launch element in the... The specific expressions for the frequency-hopping linear frequency modulation phase within each sub-pulse are as follows: ； ； in, Indicates the first Local time within each sub-pulse Indicates the first The first launch element in the... Frequency offset selected within each sub-pulse Represents the linear frequency modulation slope, satisfying , Indicates the frequency modulation bandwidth within the sub-pulse; This indicates the frequency hopping linear frequency modulation phase compensation term; Furthermore, the frequency hopping linear frequency modulation phase compensation term satisfies the following conditional expression: ； S2. Based on step S1, design a frequency combination and continuous phase modulation symbol joint embedding method for communication information to generate a transductive integrated transmission signal with continuous phase between sub-pulses. First, a frequency combination codebook and a continuous phase modulation symbol codebook are constructed. Then, the communication bits are divided into frequency combination bit blocks and continuous phase modulation symbol bit blocks, and dictionary mapping is performed on each. Next, the ordered frequency combination codewords and continuous phase modulation symbol vectors are allocated through common permutation. Finally, a continuous phase frequency hopping MIMO inductive integrated transmission signal is generated based on the allocated frequency offset and continuous phase modulation symbols. S3. Based on the integrated inductive transmission signal generated in step S2, design a projection energy incoherent demodulation method at the communication receiver to recover the communication bits; First, a frequency-symbol joint template is constructed at the communication receiver. Based on the matching projection energy of the received subpulse and the candidate template, an incoherent demodulation criterion is established to realize frequency combination and symbol vector recovery without precise channel phase prior. Then, the communication bits are recovered based on dictionary inverse mapping. S4. Based on the integrated sensing transmission signal generated in step S2, design a structure-matching coherent processing method at the radar receiver to form a coarse-range-velocity-fine-range three-dimensional sensing response, and perform three-dimensional detection and target parameter estimation. First, the radar echo is processed by receiving beamforming and frequency branch downconversion. Then, a frequency branch baseband reference signal is constructed and frequency branch matched filtering is performed. Next, velocity-consistent Doppler focusing is performed on a unified physical velocity grid. Finally, based on the obtained range-velocity response matrices of each frequency branch, frequency aperture focusing is performed to form a coarse range-velocity-fine range three-dimensional sensing response, and three-dimensional detection and target parameter estimation are performed.

2. The signal generation and processing method according to claim 1, characterized in that, Step S2 is as follows: S21. Construct a frequency combination codebook and a continuous phase modulation symbol codebook; Based on step S1, frequency offset set The frequency is set at equal intervals, meaning that the offset between adjacent candidate frequencies satisfies... ; Then from the frequency offset set Selected from Each distinct frequency offset constitutes a frequency combination codeword, and the number of candidate frequency combinations is . Furthermore, the communication bits are mapped using binary, and one of them is taken. The candidate frequency combinations constitute the actual ordered frequency combination codebook, and the remaining candidate frequency combinations are reserved combinations. in, This indicates the number of communication bits carried by the frequency combination, and The ordered frequency combination codebook The expression is as follows: ； in, Indicates the first A codeword with ordered frequency combinations, ; Indicates the first In the ordered frequency combination codeword, the first Each component in the frequency offset set The corresponding frequency index, And satisfy ; Indicates the transpose operation; Then from the continuous phase modulation symbol set The continuous phase modulation symbol vector codebook is constructed as follows: ； in, Indicates the first A continuous phase modulation symbol vector codeword, ; Indicates the first In the nth continuous phase modulation symbol vector codeword Each component in the continuous phase modulation symbol set The corresponding symbol index in ; Represents a set of continuous phase modulation symbols Construction length is The set of continuous phase modulation symbol vectors; This represents the number of communication bits carried by the continuous phase modulation symbol vector, and ; S22. Divide the communication bits into frequency combination bit blocks and continuous phase modulation symbol bit blocks, and perform dictionary mapping for each; The first The communication bits to be transmitted within each sub-pulse are divided into frequency combination bit blocks and continuous phase modulation symbol bit blocks, represented as follows: and And combine codebooks according to frequency Bit tag mapping function The frequency combination bit blocks are mapped to ordered frequency combination codewords based on the continuous phase modulation symbol vector codebook. Bit tag mapping function The expression for mapping a block of continuously phase modulated symbols (BMS) to a vector of continuously phase modulated symbols is as follows: ； in, The bit mapping function representing the frequency combination codebook, The bit mapping function represents the codebook of continuous phase modulation symbols. Indicates the first The ordered frequency combination codewords corresponding to each sub-pulse Indicates the first The continuous phase modulation symbol vector corresponding to each sub-pulse; S23. Based on step S22, perform common permutation allocation on the ordered frequency combination codeword and the continuous phase modulation symbol vector; Introducing the first The common permutation matrix corresponding to each sub-pulse The ordered frequency combination and continuous phase modulation symbol vector obtained in step S22 are synchronously permuted to obtain the frequency offset vector and continuous phase modulation symbol vector allocated to each MIMO transmitter element, as expressed below: ； in, Indicates the first The common permutation matrix corresponding to each sub-pulse This represents the frequency offset vector allocated to each MIMO transmitter element; This represents the continuous phase modulation symbol vector allocated to each MIMO transmitter element; S24. Based on step S23, generate a continuous phase frequency hopping MIMO inductive integrated transmission signal according to the allocated frequency offset and continuous phase modulation symbols. The result obtained in step S23 and Substituting the continuous phase frequency hopping MIMO integrated sensing transmit waveform model constructed in step S1, the first... Continuous phase frequency hopping MIMO baseband transmission signal of each transmitting element The transmitted signals from all the transmitting array elements constitute a synthetic integrated transmitted signal vector. The expression is as follows: 。 3. The signal generation and processing method according to claim 2, characterized in that, Step S3 is as follows: First, after completing the sub-pulse timing synchronization at the communication receiving end, the first... The received signal segment corresponding to each subpulse is denoted as , ; in, Indicates sub-pulse width; received signal segment Including The first launch element in the... The result of the superposition of frequency-symbol components transmitted within each sub-pulse, and the communication reception noise; Then, based on the frequency offset set in step S2 and continuous phase modulation symbol set Construct a frequency-symbol joint template for the th Candidate frequency offset and the Candidate continuous phase modulation symbols The corresponding local template The expression is as follows: ； in, Indicates the linear frequency modulation slope. Indicates the continuous phase modulation index. Represents the continuous phase modulation phase pulse function; the number of constructed frequency-symbol joint templates is... ; Then the first The received signal segment of each sub-pulse The projection result is obtained by matching and projecting the result with the joint template of each frequency and symbol, as shown in the following expression: ； in, Indicates conjugate operation; Then, a projection energy table is established based on the squared magnitude of the projection result, as shown in the following expression: ； in, Indicates the first Subpulse at candidate frequency and candidate symbols Projected energy below; Based on the projected energy table, the energy of the continuous phase modulation symbol dimension corresponding to each candidate frequency is maximized to obtain the frequency energy statistics. The expression is as follows: ； Then, the ordered frequency combination codebook constructed in step S2 is further processed. Calculate the energy metric for each ordered frequency combination codeword one by one; Energy measurement of a frequency combination codeword The expression is as follows: ； in, Indicates the first The first sub-pulse Energy measure of an ordered frequency combination codeword; This indicates the codeword number. Frequency energy statistics corresponding to each frequency offset; Then, frequency combination recovery is performed based on the energy metric of the frequency combination codewords. That is, among the ordered frequency combination codewords, the codeword with the largest energy metric is selected as the first codeword. The frequency combination recovery result of the sub-pulses is expressed as follows: ； in, Indicates the first The ordered frequency combination codeword index obtained by recovering each sub-pulse; This represents the recovered ordered frequency combination codeword; This indicates the first element in the recovered ordered frequency combination codeword. Each component in the frequency offset set The corresponding frequency index, ; Given the recovered frequency combination order, the energy metric of the candidate symbol vectors in the continuous phase modulation symbol vector codebook is calculated as follows: ； in, Indicates the first The first sub-pulse Energy metric of candidate continuous phase modulation symbol vector codewords ; Then, symbol vector recovery is performed based on the energy metric of the continuous phase modulation symbol vector. That is, among all continuous phase modulation symbol vector codewords, the codeword with the largest energy metric is selected as the first codeword. The expression for the recovery result of the continuous phase modulation symbol vector of each subpulse is as follows: ； in, Indicates the first Index of the continuous phase modulation symbol vector obtained from the recovery of each sub-pulse. This represents the recovered continuous phase modulation symbol vector; The recovered frequency combination codeword and continuous phase modulation symbol vector are inversely mapped to obtain the first... The communication bits carried by each sub-pulse are expressed as follows: ； in, The inverse mapping function representing the frequency combination codebook, The inverse mapping function representing the continuous phase modulation symbol codebook, and These represent the recovered frequency combination bit block and the continuous phase modulation symbol bit block, respectively; Ultimately, and Merge to obtain the first The communication bits recovered from each sub-pulse.

4. The signal generation and processing method according to claim 3, characterized in that, Step S4 is as follows: S41. Perform receive beamforming and frequency branching downconversion processing on the radar received echo; At the radar receiver, for continuous The echo signal of the pulse is coherently processed; then the pulse echo signal is coherently processed. The received echo of each pulse is used for receiving beamforming to obtain the received echo signal. and in accordance with the first Each frequency branch is down-converted to obtain the down-converted signal. The expression is as follows: ； in, , Indicates the number of coherent processing pulses. , Indicates the number of frequency branches. Indicates the first One frequency offset; S42. Construct a frequency branch baseband reference signal and perform frequency branch matched filtering; Based on the known continuous phase frequency hopping MIMO waveform, frequency allocation results, and array orientation assumptions at the transmitter, the first... The pulse, the first Each frequency branch under the angle assumption Directional transmission reference signal The directional transmission reference signal is processed into baseband to obtain the first... The baseband reference signal corresponding to each frequency branch The expression is as follows: ； The frequency branch echo signal obtained in step S41 The frequency branch matched response is obtained by performing matched filtering with the baseband reference signal. The expression is as follows: ； in, Represents the fine-distance delay variable; For coarse distance delay mesh Calculate the matched filter output point by point to obtain the first... The pulse, the first Coarse-range matched response on each frequency branch , Indicates coarse distance cell index; S43. Perform velocity-consistent Doppler focusing on a uniform physical velocity grid; Arrange the frequency branch matching responses obtained in step S42 according to the pulse sequence number to construct the first... Distance between frequency branches—slow-time response matrix The expression is as follows: ； in, Indicates the first The pulse, the first Coarse-range matched response of each frequency branch; Then, velocity-consistent Doppler focusing is performed on a unified physical velocity grid, assuming the velocity search grid is... , No. Each frequency branch in speed The corresponding Doppler frequency The expression is as follows: ； in, To represent the speed of light, the unified physical velocity mesh expression is as follows: ； in, ； in, , Indicates the number of velocity grids. Indicates the velocity grid interval. This indicates the maximum unambiguous velocity that all frequency branches jointly satisfy. Indicates the pulse repetition period; Based on the Doppler frequency, the first... Slow-time coherent focusing is performed on each frequency branch to obtain the range-velocity response matrix. The expression is as follows: ； in, Indicates the first Distance-velocity response matrix of each frequency branch, Indicates coarse distance cell index; S44. Based on the distance-velocity response matrices of each frequency branch obtained in step S43, frequency aperture focusing is performed to form a coarse distance-velocity-fine distance three-dimensional sensing response. After completing velocity focusing for each frequency branch, fine-distance focusing is performed using discrete frequency apertures formed by different frequency branches; Each frequency branch in speed The equivalent frequency expression is as follows: ； in, Indicates the equivalent frequency used when performing frequency aperture focusing; In fine-distance delay variables Below, in the finer distance dimension, phase compensation and coherent accumulation are performed on the distance-velocity response of each frequency branch to obtain the frequency aperture focusing output, as expressed below: ； in, Represents coarse distance cells Speed ​​unit and fine-distance delay variables The following is the focusing result; Then in fine-distance delay mesh The above calculation of the frequency aperture focusing output yields the three-dimensional sensing response of coarse distance—velocity—fine distance, as expressed below: ； in, Indicates the number of fine-pitch grid cells; Indicates the total number of fine-pitch grid cells; S45. Perform three-dimensional detection and target parameter estimation based on the coarse-range-velocity-fine-range three-dimensional sensing response obtained in step S44; Based on the three-dimensional perception response obtained in step S44, a detection statistic is constructed. The expression is as follows: ； The detection statistics are subjected to threshold decision to obtain the target detection unit set, as shown in the following expression: ； in, Indicates the detection threshold. Represents a set of target detection units; The detection threshold is determined using a preset threshold or a constant false alarm rate (CFAR) detection threshold, for local maximum units within the detection unit. According to its velocity unit index Obtain the target velocity estimate The expression is as follows: ； Based on fine-pitch units Obtain the fine distance estimate within the frequency aperture period. The expression is as follows: ； velocity unit The frequency-aperture distance period expression is as follows: ； in, Representing velocity unit The equivalent frequency interval between adjacent frequency branches is defined by the following expression: ； When the frequency branch meets the equal interval setting Sometimes, ; According to coarse distance unit Corresponding coarse distance center Determine the distance fuzzy branch number The expression is as follows: ； in, Represents the integer field. The variable to be solved represents the fuzzy branch number of the distance; the final target distance estimate. The expression is as follows: 。

Images