Interference communication integrated signal design method based on MIMO-OCDM

Abstract

The invention provides an interference communication integrated signal design method based on MIMO-OCDM (Multiple Input Multiple Output-Optical Code Division Multiplexing). The implementation steps are as follows: constructing an application scene of an interference communication integrated signal and a binary communication data matrix; performing OCDM on the binary communication data matrix, and obtaining an MIMO-OCDM communication signal and a frequency shift interference signal; and finally, an MIMO-OCDM interference communication integrated signal is obtained. According to the method, Hadamard matrix coding is carried out on the time domain signal matrix obtained after discrete Fresnel inverse transformation is carried out on the frequency domain QPSK symbol matrix so as to obtain the MIMO-OCDM communication signal matrix, it is guaranteed that multiple time domain signals have the high anti-interference capacity, interference of signals between MIMO transmitting channels is reduced, and the communication performance of the MIMO-OCDM communication signal matrix is improved. Moreover, a non-partner needs to obtain the interference communication integrated signals transmitted by all MIMO transmission channels and correctly analyze and recombine the interference communication integrated signals to obtain the communication data, thereby improving the anti-interference difficulty of the radar of the opposite side.

Description

Technical Field

[0001] This invention belongs to the field of radar technology, specifically relating to a MIMO-OCDM-based integrated jamming and communication signal design method, which can be applied to UAV swarm platforms that integrate jamming and communication functions. Background Technology

[0002] Integrated interference signal refers to the multiplexing of communication signals and interference signals into the same signal. By sharing time and frequency resources, modulation structures or signal waveforms, it can interfere with the electronic systems of non-cooperative parties while transmitting communication information.

[0003] The technical approach to designing an integrated jamming and communication signal is as follows: First, the communication data stream is converted from serial to parallel, and then the communication signal is obtained through mapping modulation. Then, the intercepted non-cooperative radar detection signal is frequency-shifted and forwarded to obtain a frequency-shifted jamming signal with deceptive jamming effect. Finally, the communication signal and the frequency-shifted jamming signal are combined in the time domain to obtain an integrated jamming and communication signal.

[0004] To overcome the shortcomings of existing integrated communication jamming signals, which have low anti-jamming difficulty for enemy radars but high communication error rates for friendly radars, patent application CN202211072418.4, entitled "Design and Processing Method of Integrated Communication Jamming Signal Based on FRFT," discloses a method for designing integrated communication jamming signals. This invention utilizes the characteristic that integrated communication jamming signals with different frequency change rate parameters have different optimal orders of fractional Fourier transform (FRFT) to generate integrated communication jamming signals with dense false target characteristics. This invention solves the problems of non-coherence between artificial noise and enemy radar signals and the susceptibility of OFDM integrated signals to multipath effects, overcomes the deficiency that real targets and jamming targets are easily separated by enemy radars, improves the anti-jamming difficulty for enemy radars, and reduces the communication error rate of friendly radars. However, because the FRFT-based integrated communication jamming signal lacks time-frequency orthogonality and interference occurs between signals, it affects the further reduction of the communication error rate for friendly radars. Furthermore, the integrated communication jamming signal is transmitted through a single antenna, which further hinders the improvement of the anti-jamming difficulty for enemy radars. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and propose an integrated signal design method for jamming and communication based on MIMO-OCDM, which is used to solve the technical problems of low anti-jamming difficulty for enemy radar and high bit error rate for communication with friendly radar in the existing technology.

[0006] (1) Constructing application scenarios for the integrated interference communication signal to be designed:

[0007] An application scenario for an integrated jamming and communication signal to be designed is constructed, which includes non-cooperative aircraft distributed in three-dimensional space and an integrated jamming and communication system set on the ground. The integrated jamming and communication system includes a multi-input multi-output MIMO receiving antenna and a transmitting antenna with M channels, and a signal processing unit, where M>1, and the radar detection signal transmitted by the non-cooperative aircraft is r.

[0008] (2) The signal processing unit constructs a binary communication data matrix:

[0009] The signal processing unit performs serial-to-parallel conversion on the generated serial binary communication data stream s of length L, and constructs a binary communication data matrix x of dimension M×K based on the conversion result;

[0010] (3) The signal processing unit performs OCDM on the binary communication data matrix:

[0011] The signal processing unit constructs a frequency domain QPSK symbol matrix using a binary communication data matrix x, and performs a discrete inverse Fresnel transform on the frequency domain QPSK symbol matrix to obtain a time domain signal matrix X with dimension M×N;

[0012] (4) The signal processing unit acquires MIMO-OCDM communication signals:

[0013] The signal processing unit performs Hadamard matrix encoding on the time-domain signal matrix X to obtain a MIMO-OCDM communication signal matrix Y with dimension M×N, where the MIMO-OCDM communication signal of the m-th transmit channel is Y. m ;

[0014] (5) The signal processing unit acquires the MIMO-OCDM frequency shift interference signal:

[0015] The signal processing unit samples the radar detection signal r intercepted by each receiving antenna from a non-cooperative aircraft N times, and processes each sampled discrete radar detection signal r... m (n) performs frequency shifting and forwarding to obtain M×N discrete frequency shifting interference signals;

[0016] (6) The signal processing unit acquires the integrated MIMO-OCDM interference communication signal:

[0017] The signal processing unit processes each time-domain encoded signal Y in the MIMO-OCDM communication signal matrix Y. m [n] corresponds to the discrete frequency shifting interference signal J among M×N discrete frequency shifting interference signals. m (n) Perform time-domain composite to obtain M integrated MIMO-OCDM jamming and communication signals for transmission channels.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] This invention achieves OCDM modulation of the binary communication data matrix by performing discrete Fresnel inverse transform on the frequency domain QPSK symbol matrix, thereby obtaining multiple time-domain signals that are strictly orthogonal in both the time and frequency domains and have greater anti-interference capabilities. Simultaneously, by performing Hadamard matrix encoding on the time-domain signal matrix to obtain the MIMO-OCDM communication signal matrix, it ensures that the signals on each transmission channel are mutually orthogonal and do not interfere with signals from other transmission channels, reducing the communication error rate for friendly radar. Furthermore, non-cooperative parties must obtain the integrated interference communication signals transmitted from all MIMO transmission channels and correctly parse and reassemble them to obtain communication data, increasing the difficulty of anti-interference against enemy radar. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the implementation of the present invention.

[0021] Figure 2 This is a schematic diagram illustrating the application scenario of the integrated interference and communication signal of the present invention. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] Reference Figure 1 The implementation process of this invention is as follows:

[0024] Step 1) Construct as follows Figure 2 The application scenarios of the integrated interference communication signal shown are as follows:

[0025] An application scenario for an integrated jamming and communication signal to be designed is constructed, which includes non-cooperative aircraft distributed in three-dimensional space and an integrated jamming and communication system set on the ground. The integrated jamming and communication system includes a multi-input multi-output MIMO with M channels for receiving and transmitting antennas, and a signal processing unit, where M>1, and the radar detection signal transmitted by the non-cooperative aircraft is r.

[0026] The MIMO receiving antenna is used to intercept radar detection signals transmitted by non-cooperative aircraft; the signal processing unit is used to process the generated binary communication data stream and the intercepted radar detection signals to obtain an integrated jamming and communication signal; the MIMO transmitting antenna is used to transmit the integrated jamming and communication signal.

[0027] Step 2) The signal processing unit constructs the binary communication data matrix:

[0028] The signal processing unit performs serial-to-parallel conversion on the generated serial binary communication data stream s of length L, and constructs a binary communication data matrix x of dimension M×K based on the conversion result;

[0029] The construction method is as follows: The signal processing unit generates a serial binary communication data stream s consisting of M groups, each containing K binary communication data points of length L, and performs serial-to-parallel conversion on it. Then, it constructs a binary communication data matrix x with M×K dimensions, where the M groups of converted binary communication data are the rows and the K binary communication data points in each group are the columns, and L≥4. Indicates rounding up;

[0030] The binary communication data x in row m and column k. m The expression for [k] is:

[0031] x m [k] = s[k + (m - 1)K]

[0032] Where m represents the index of M, m∈{1,2,...,M}, and k represents the index of K, k∈{1,2,...,K}.

[0033] The serial-to-parallel conversion transforms a single-channel serial binary communication data stream into multiple-channel parallel binary communication data streams. The number of parallel channels matches the number of MIMO transmission channels. Each transmission channel has independent binary communication data. Non-cooperative parties need to simultaneously acquire the signals transmitted by all transmission channels and correctly parse and reassemble them in order to obtain the communication data, which increases the difficulty of anti-jamming against the other party's radar.

[0034] Step 3) The signal processing unit performs OCDM on the binary communication data matrix:

[0035] The signal processing unit constructs a frequency domain QPSK symbol matrix using a binary communication data matrix x, and performs a discrete inverse Fresnel transform on the frequency domain QPSK symbol matrix to obtain a time domain signal matrix X with dimension M×N;

[0036] Because the acquired time-domain signal is strictly orthogonal in the time and frequency domains, the anti-interference capability of the time-domain signal is improved, thereby reducing the communication error rate with one's own radar.

[0037] (3a) The signal processing unit processes each binary communication data x in the binary communication data matrix x. m [k] Perform QPSK modulation to map every two binary communication data in each row to a frequency-domain QPSK symbol, resulting in a frequency-domain QPSK symbol matrix d of dimension M×N, where:

[0038]

[0039] Where, d m [n] represents the sum of x m[k] is the QPSK symbol in the m-th row and n-th column after QPSK modulation, where n represents the index of N, n∈{1,2,...,N}, and N represents the number of frequency domain QPSK symbols in each row;

[0040] QPSK is a digital modulation technique, a type of phase-shift keying, that maps two binary communication data points to a frequency-domain QPSK symbol. The frequency-domain QPSK symbol is represented using complex numbers, with binary data 00 corresponding to a complex number. Binary data 01 corresponds to complex numbers The binary number 10 corresponds to the complex number The binary number 11 corresponds to the complex number

[0041] (3b) The signal processing unit performs a discrete inverse Fresnel transform on the frequency domain QPSK symbol matrix d to achieve the frequency domain-to-time domain conversion, obtaining a time domain signal matrix X of dimension M×N, where the time domain signal X in the m-th row and n-th column is... m The expression for [n] is:

[0042]

[0043] Where p represents the index of P, and P = N.

[0044] X m [n] is the number n and all frequency domain QPSK symbols in the m-th row. Regarding, if using This would conflict with the number n, so p is used to distinguish it from n. P is numerically equal to N, through... To represent all frequency domain QPSK symbols in the corresponding row, we can avoid conflicts with the number n.

[0045] Step 4) The signal processing unit acquires the MIMO-OCDM communication signal:

[0046] The signal processing unit performs Hadamard matrix encoding on the time-domain signal matrix X to obtain a MIMO-OCDM communication signal matrix Y with dimension M×N, where the MIMO-OCDM communication signal of the m-th transmit channel is Y. m ;

[0047] The MIMO-OCDM communication signal Y of the m-th transmission channel m The expression is:

[0048] Y m =X m H

[0049] Among them, X m Let H represent the time-domain signal of the m-th transmission channel, and let H represent the Hadamard matrix, where H∈{-1,1}. N×N.

[0050] X m It contains N time-domain signals, Y m Containing N time-domain coded signals, the Hadamard matrix is ​​a special orthogonal matrix whose elements consist only of +1 and -1, and any two rows or two columns are mutually orthogonal.

[0051] The signal processing unit performs Hadamard matrix encoding on the time-domain signal matrix X. The purpose of this is to ensure that the signals on each transmission channel are orthogonal to each other, avoid signal interference between transmission channels, and reduce the communication error rate of the radar.

[0052] Step 5) The signal processing unit acquires the MIMO-OCDM frequency shift interference signal:

[0053] The signal processing unit samples the radar detection signal r intercepted by each receiving antenna from a non-cooperative aircraft N times, and processes each discrete radar detection signal r from each transmitted channel. m (n) performs frequency shifting and forwarding to obtain M×N discrete frequency shifting interference signals;

[0054] Each transmission channel, each discrete radar detection signal r m The expression for (n) is:

[0055]

[0056] Among them, f0, μ, T S Let r represent the carrier frequency, frequency modulation slope, and sampling period of the radar detection signal r, respectively; e represents the base of the natural logarithm; and j represents the imaginary unit.

[0057] Each transmission channel, each discrete radar detection signal r m (n), whose corresponding discrete frequency shift interference signal J m The expression for (n) is:

[0058]

[0059] Where Δf and B represent the frequency shift and bandwidth of the radar detection signal r, respectively.

[0060] Each receiving antenna intercepts the same radar detection signal r transmitted by a non-cooperative aircraft. With M receiving antennas, M radar detection signals r are intercepted. Each r is sampled N times, resulting in M×N discrete radar detection signals r. m (n), for each discrete radar detection signal r m (n) Perform frequency shift forwarding to obtain M×N discrete frequency shift interference signals J m (n), each J m (n) is in the corresponding rm The frequency shift (n) is obtained by a shift of Δf.

[0061] Step 6) The signal processing unit acquires the integrated MIMO-OCDM interference and communication signal:

[0062] The signal processing unit processes each time-domain encoded signal Y in the MIMO-OCDM communication signal matrix Y. m [n] corresponds to the discrete frequency shifting interference signal J among M×N discrete frequency shifting interference signals. m (n) Perform time-domain composite to obtain M integrated MIMO-OCDM jamming and communication signals for transmission channels.

[0063] The integrated MIMO-OCDM jamming and communication signal for the m-th transmission channel is s. m The expression is:

[0064]

[0065]

[0066] Where α represents J m The interference amplitude coefficient of (n), A max This represents the maximum allowable signal amplitude of the integrated system, and max|·| represents the maximum instantaneous amplitude of the signal.

[0067] Here, time-domain compositing refers to each time-domain coded signal Y in the MIMO-OCDM communication signal matrix Y. m [n] corresponds to the discrete frequency shifting interference signal J among M×N discrete frequency shifting interference signals. m (n) The time domain is added together to obtain M integrated MIMO-OCDM jamming and communication signals, which are transmitted through the corresponding M transmitting antennas. Non-cooperative parties need to simultaneously obtain the signals transmitted by all transmission channels and correctly parse and reassemble them in order to obtain communication data, which increases the difficulty of anti-jamming against the other party's radar.

[0068] Simultaneously, the power ratio of the two signals needs to be dynamically adjusted to avoid excessively strong or weak interference. The value of α should be set according to the linear range of the integrated system to prevent s m The amplitude exceeds the linear range of the system's digital-to-analog converter power amplifier, thus avoiding signal clipping distortion.

Claims

1. A method for designing integrated jamming and communication signals based on MIMO-OCDM, characterized in that, Includes the following steps: (1) Constructing application scenarios for the integrated interference communication signal to be designed: An application scenario for an integrated jamming and communication signal to be designed is constructed, which includes non-cooperative aircraft distributed in three-dimensional space and an integrated jamming and communication system set on the ground. The integrated jamming and communication system includes a multi-input multi-output MIMO receiving antenna and a transmitting antenna with M channels, and a signal processing unit, where M>1, and the radar detection signal transmitted by the non-cooperative aircraft is r. (2) The signal processing unit constructs a binary communication data matrix: The signal processing unit performs serial-to-parallel conversion on the generated serial binary communication data stream s of length L, and constructs a binary communication data matrix x of dimension M×K based on the conversion result; (3) The signal processing unit performs OCDM on the binary communication data matrix: The signal processing unit constructs a frequency domain QPSK symbol matrix using a binary communication data matrix x, and performs a discrete inverse Fresnel transform on the frequency domain QPSK symbol matrix to obtain a time domain signal matrix X with dimension M×N; (4) The signal processing unit acquires MIMO-OCDM communication signals: The signal processing unit performs Hadamard matrix encoding on the time-domain signal matrix X to obtain a MIMO-OCDM communication signal matrix Y with dimension M×N, where the MIMO-OCDM communication signal of the m-th transmit channel is Y. m ; (5) The signal processing unit acquires the MIMO-OCDM frequency shift interference signal: The signal processing unit samples the radar detection signal r intercepted by each receiving antenna from a non-cooperative aircraft N times, and processes each discrete radar detection signal r from each transmitted channel. m (n) performs frequency shifting and forwarding to obtain M×N discrete frequency shifting interference signals; (6) The signal processing unit acquires the integrated MIMO-OCDM interference communication signal: The signal processing unit processes each time-domain encoded signal Y in the MIMO-OCDM communication signal matrix Y. m [n] corresponds to the discrete frequency shifting interference signal J among M×N discrete frequency shifting interference signals. m (n) Perform time-domain composite to obtain M integrated MIMO-OCDM jamming and communication signals for transmission channels.

2. The method according to claim 1, characterized in that, The binary communication data matrix mentioned in step (2) is constructed as follows: The signal processing unit generates a serial binary communication data stream s consisting of M groups, each containing K binary communication data points of length L. It then performs a serial-to-parallel conversion on the s stream and constructs a binary communication data matrix x of dimension M×K, with the M converted binary communication data groups as rows and the K binary communication data points in each group as columns, where L≥4. This indicates rounding up to the nearest integer.

3. The method according to claim 2, characterized in that, The binary communication data matrix x in step (2) is given by x, where the binary communication data in the m-th row and k-th column is x. m [k], whose expression is: x m [k]=s[k+(m-1)K] Where m represents the index of M, m∈{1,2,...,M}, and k represents the index of K, k∈{1,2,...,K}.

4. The method according to claim 3, characterized in that, The signal processing unit described in step (3) performs OCDM on the binary communication data matrix, and the implementation steps are as follows: (3a) The signal processing unit processes each binary communication data x in the binary communication data matrix x. m [k] Perform QPSK modulation to map every two binary communication data in each row to a frequency-domain QPSK symbol, resulting in a frequency-domain QPSK symbol matrix d of dimension M×N, where: Where, d m [n] represents the sum of x m [k] is the QPSK symbol in the m-th row and n-th column after QPSK modulation, where n represents the index of N, n∈{1,2,...,N}, and N represents the number of frequency domain QPSK symbols in each row; (3b) The signal processing unit performs a discrete inverse Fresnel transform on the frequency domain QPSK symbol matrix d to achieve the frequency domain-to-time domain conversion, obtaining a time domain signal matrix X of dimension M×N, where the time domain signal X in the m-th row and n-th column is... m The expression for [n] is: Where p represents the index of P, and P = N.

5. The method according to claim 4, characterized in that, The MIMO-OCDM communication signal Y of the m-th transmission channel mentioned in step (4) m The expression is: Y m =X m H Among them, X m Let H represent the time-domain signal of the m-th transmission channel, and let H represent the Hadamard matrix, where H∈{-1,1}. N×N .

6. The method according to claim 4, characterized in that, Each discrete radar detection signal r for each transmission channel described in step (5) m (n), whose expression is: Among them, f0, μ, T S Let r represent the carrier frequency, frequency modulation slope, and sampling period of the radar detection signal r, respectively; e represents the base of the natural logarithm; and j represents the imaginary unit.

7. The method according to claim 6, characterized in that, Each discrete radar detection signal r for each transmission channel described in step (5) m (n), whose corresponding discrete frequency shift interference signal is J. m (n), the expression is: Where Δf and B represent the frequency shift and bandwidth of the radar detection signal r, respectively.

8. The method according to claim 7, characterized in that, The integrated MIMO-OCDM jamming and communication signal for the M transmission channels mentioned in step (6), wherein the integrated MIMO-OCDM jamming and communication signal for the m-th transmission channel is s m The expression is: Where α represents J m The interference amplitude coefficient of (n), A max This represents the maximum allowable signal amplitude of the integrated system, and max|·| represents the maximum instantaneous amplitude of the signal.

Images