A radar communication integrated signal optimization method

Abstract

The application discloses a radar communication integrated signal optimization method and belongs to the technical field of radar communication integration. The application constructs a multi-pulse OFDM integrated signal model, designs an ICI self-cancellation precoding matrix based on frequency offset and Doppler effect, and suppresses inter-subcarrier interference; meanwhile, an inter-pulse coherent communication sequence is designed by combining Gold sequences and coherent accumulation constraints, so that the multi-pulse phase coherence is ensured. The transmitting end loads the precoded communication information to OFDM subcarriers to generate an integrated signal; the receiving end first performs ICI compensation and coherent accumulation, and then completes detection and demodulation. The application can significantly reduce waveform sidelobes, improve ranging and speed measurement accuracy and weak target detection performance, is compatible with a traditional OFDM structure, and is suitable for high-speed motion scenes such as vehicle-mounted radars and airborne detection.

Description

Technical Field

[0001] This invention belongs to the field of radar communication technology, and more specifically, relates to an optimization method for integrated radar communication signals. Background Technology

[0002] Traditional radar-communication integrated signals often employ OFDM waveform embedding of communication information. This method loads multiple OFDM symbols into the radar transmit pulse and modulates the communication data, thus combining radar detection and communication transmission functions. Existing technologies typically reduce the impact of communication information on the radar waveform ambiguity function by performing sequential pre-modulation of the communication modulation information, thereby obtaining an integrated signal that is insensitive to communication information.

[0003] For example, 201510443619.4 describes an optimization method for radar-communication integrated signals. The main idea is to determine the working mode of the radar-communication integrated system and use the radar pulse transmission method to obtain Ns OFDM symbols contained in one radar pulse. Then, the baseband form of the radar pulse and the baseband form of the radar pulse after a delay time τ are obtained respectively. Based on these two baseband forms, the ambiguity function of the radar-communication integrated waveform is obtained. Then, the specific form of the ambiguity function of the radar-communication integrated waveform and the communication modulation information modulated by the nth OFDM symbol carrier in the same pulse are obtained respectively. Based on the specific form of the ambiguity function of the radar-communication integrated waveform, the communication modulation information a(n) modulated by the nth OFDM symbol carrier in the same pulse is pre-modulated using a Gold sequence to obtain a radar-communication integrated signal that is insensitive to communication modulation information.

[0004] However, the aforementioned disclosed technology still has the following drawbacks:

[0005] 1. Gold sequence premodulation is only performed on the communication modulation information, without suppressing OFDM inter-carrier interference (ICI). In the presence of frequency offset, time-varying channel and Doppler effect, inter-carrier interference will significantly degrade the ambiguity function, increase waveform sidelobes, and reduce radar ranging and velocity measurement accuracy.

[0006] 2. Only a single-pulse signal model is established without considering the constraints of multi-pulse coherent accumulation on the communication sequence. The communication information will destroy the inter-pulse coherence, resulting in a decrease in coherent accumulation gain and affecting the weak target detection performance.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0009] An optimization method for integrated radar and communication signals includes the following steps:

[0010] Step 1: Determine the operating parameters of the integrated radar and communication system and establish a multi-pulse OFDM integrated radar and communication signal model;

[0011] Step 2: Perform dual pre-modulation processing on the communication modulation information to reduce the impact of the communication information on the radar waveform;

[0012] Step 3: Based on the multi-pulse coherent accumulation constraint, perform phase calibration on the pre-modulated communication modulation information sequence to ensure inter-pulse coherence;

[0013] Step 4: Load the phase-calibrated communication modulation information onto the OFDM subcarrier to generate OFDM symbols, which are then used to form radar transmission pulses, thus completing the generation of the integrated multi-pulse radar communication signal.

[0014] Step 5: Verify the performance of the generated optimized radar-communication integrated signal. If it meets the preset radar detection accuracy and communication transmission quality requirements, output the signal. If it does not meet the requirements, adjust the ICI suppression coding parameters in step S2 and the coherent threshold in step S3, and repeat steps 2-4 until the requirements are met.

[0015] In a preferred embodiment of the present invention, the operating parameters in step 1 include the radar transmit pulse repetition frequency (PRF), the number of OFDM symbols Ns in each radar transmit pulse, the number of OFDM subcarriers Nc, the subcarrier spacing Δf, the communication modulation method, and the radar detection range. The multi-pulse OFDM radar-communication integrated signal model includes M continuously transmitted radar pulses, each pulse containing Ns OFDM symbols, each OFDM symbol consisting of Nc subcarriers, and each subcarrier is loaded with communication modulation information, while ensuring the coherence constraint between adjacent pulses.

[0016] In a preferred embodiment of the present invention, step 2, specifically the dual premodulation process, involves: firstly, using a Gold sequence to premodulate the original communication modulation information to reduce the fundamental impact of the communication information on the radar ambiguity function; then, using ICI suppression coding to premodulate the communication information after the first premodulation. The ICI suppression coding employs a pilot-assisted differential coding method, which estimates the channel state by inserting known pilot symbols, and simultaneously utilizes the redundancy characteristics of differential coding to reconstruct the signal, offsetting energy leakage between subcarriers and suppressing ICI interference, thereby obtaining the premodulated communication modulation information sequence.

[0017] In a preferred embodiment of the present invention, step S3 specifically involves: calculating the phase difference between the corresponding OFDM symbols and the pre-modulated communication information on the corresponding subcarriers in two adjacent radar pulses; compensating the phase of the communication modulation information of each pulse based on a preset coherent threshold, so that the phase difference between the corresponding subcarriers of adjacent pulses is controlled within the preset threshold range, ensuring phase consistency during multi-pulse coherent accumulation; and simultaneously introducing the autocorrelation characteristics of the Gore-Ley complementary waveform to further suppress sidelobe interference during coherent accumulation and improve accumulation gain.

[0018] In a preferred embodiment of the present invention, step 4 specifically involves: mapping the phase-calibrated communication modulation information onto the corresponding OFDM subcarriers, and generating each OFDM symbol through IFFT transformation, windowing processing, and digital-to-analog conversion; the windowing processing uses a Hanning window to reduce energy leakage at the subcarrier edges and further suppress ICI interference; combining Ns OFDM symbols sequentially to form a single radar transmit pulse, and repeatedly generating M consecutive radar transmit pulses to obtain the optimized multi-pulse radar communication integrated signal.

[0019] In a preferred embodiment of the present invention, in step 1, the baseband form expression of the multi-pulse OFDM radar-communication integrated signal is as follows: in, This refers to the pre-modulated communication modulation information on the m-th pulse, the n-th OFDM symbol, and the k-th subcarrier. For rectangular window functions, The pulse repetition period, For OFDM symbol period, For radar carrier frequency, The subcarrier spacing.

[0020] In a preferred embodiment of the present invention, the specific process of the ICI suppression coding in step 2 is as follows:

[0021] S21. Divide the communication information sequence after the first pre-modulation into several coding blocks, each coding block containing L communication symbols;

[0022] S22. Insert pilot symbols at the beginning and end of each coding block. The pilot symbols adopt a known orthogonal sequence and are used for channel state estimation.

[0023] S23. Perform differential coding on the coding block after inserting the pilot to generate an ICI suppression coding sequence. The coding rate of differential coding is adaptively adjusted according to the number of subcarriers and the time-varying characteristics of the channel to ensure that the communication transmission rate is not affected while suppressing ICI interference.

[0024] In a preferred embodiment of the present invention, the specific process of phase calibration in step 3 is as follows:

[0025] S31. Calculate the phase difference between the nth OFDM symbol and the premodulated communication information on the kth subcarrier in the mth pulse and the (m+1)th pulse. ;

[0026] S32, Preset coherent threshold The coherent threshold The value is determined based on the radar coherent accumulation gain requirement, and its range is 0.01π-0.05π.

[0027] S33, if Then, for the pre-modulated communication information on the nth OFDM symbol and the kth subcarrier in the (m+1)th pulse... Phase compensation is performed, and the compensation amount is... ;like Then keep constant;

[0028] S34. Repeat steps S31-S33 to complete the phase calibration between all adjacent pulses and obtain the phase-calibrated communication modulation information sequence.

[0029] In a preferred embodiment of the present invention, step 5, the performance verification specifically includes:

[0030] Radar detection accuracy verification: Calculate the ambiguity function of the optimized signal, detect the sidelobe level of the ambiguity function. If the sidelobe level is lower than the preset threshold, and the ranging accuracy error is ≤0.5m and the velocity accuracy error is ≤0.1m / s, then the radar detection accuracy requirements are met.

[0031] Communication transmission quality verification: Calculate the bit error rate (BER) of the communication signal. If the BER... If the signal is within acceptable limits, the communication transmission quality requirements are met; if any one of these requirements is not met, the coding rate, pilot insertion interval, or coherent threshold of the ICI suppression coding is adjusted, the signal is regenerated, and the verification is performed.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] This invention addresses the shortcomings of existing technologies in suppressing OFDM inter-carrier interference (ICI). Based on Gold sequence premodulation, it adds a secondary premodulation process of ICI suppression coding, combined with windowing techniques and pilot-assisted channel estimation methods. This effectively counteracts energy leakage between subcarriers caused by frequency offset, time-varying channels, and Doppler effects, significantly suppressing ICI interference, avoiding ambiguity function deterioration and waveform sidelobe rise, and greatly improving radar ranging and velocity measurement accuracy. Simultaneously, the ICI suppression coding employs an adaptive rate design, ensuring interference suppression while also considering communication transmission rate, thus solving the problem of balancing radar detection accuracy and communication rate in existing technologies.

[0034] This invention establishes an integrated signal model for multi-pulse OFDM radar communication. By using phase calibration technology to ensure the coherence between adjacent pulses and combining the autocorrelation characteristics of Gore-Ley complemented waveforms, it avoids the destruction of multi-pulse coherent accumulation by communication information, improves the coherent accumulation gain, and enhances the weak target detection performance. The phase calibration adopts an adaptive threshold design, which can be flexibly adjusted according to radar detection requirements, adapting to the weak target detection requirements in different scenarios and expanding the application range of the integrated system.

[0035] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0036] In the attached diagram:

[0037] Figure 1 This is a flowchart of an optimization method for integrated radar and communication signals. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention.

[0039] Example 1:

[0040] An optimization method for integrated radar and communication signals includes the following steps:

[0041] Step 1: Determine the operating parameters of the integrated radar and communication system and establish a multi-pulse OFDM integrated radar and communication signal model;

[0042] Step 2: Perform dual pre-modulation processing on the communication modulation information to reduce the impact of the communication information on the radar waveform;

[0043] Step 3: Based on the multi-pulse coherent accumulation constraint, perform phase calibration on the pre-modulated communication modulation information sequence to ensure inter-pulse coherence;

[0044] Step 4: Load the phase-calibrated communication modulation information onto the OFDM subcarrier to generate OFDM symbols, which are then used to form radar transmission pulses, thus completing the generation of the integrated multi-pulse radar communication signal.

[0045] Step 5: Verify the performance of the generated optimized radar-communication integrated signal. If it meets the preset radar detection accuracy and communication transmission quality requirements, output the signal. If it does not meet the requirements, adjust the ICI suppression coding parameters in step S2 and the coherent threshold in step S3, and repeat steps 2-4 until the requirements are met.

[0046] Furthermore, in step 1, the operating parameters include the radar transmit pulse repetition frequency (PRF), the number of OFDM symbols Ns in each radar transmit pulse, the number of OFDM subcarriers Nc, the subcarrier spacing Δf, the communication modulation method, and the radar detection range; the multi-pulse OFDM radar-communication integrated signal model includes M continuously transmitted radar pulses, each pulse contains Ns OFDM symbols, each OFDM symbol is composed of Nc subcarriers, and each subcarrier is loaded with communication modulation information, while ensuring the coherence constraint between adjacent pulses.

[0047] Furthermore, in step 2, the dual premodulation process specifically involves: firstly, using a Gold sequence to premodulate the original communication modulation information to reduce the fundamental impact of the communication information on the radar ambiguity function; then, using ICI suppression coding to premodulate the communication information after the first premodulation. The ICI suppression coding employs a pilot-assisted differential coding method, which uses the insertion of known pilot symbols to achieve channel state estimation, while utilizing the redundancy characteristics of differential coding to reconstruct the signal, offset energy leakage between subcarriers, suppress ICI interference, and obtain the premodulated communication modulation information sequence.

[0048] Furthermore, in step S3, the phase calibration specifically involves: calculating the phase difference between the corresponding OFDM symbols and the pre-modulated communication information on the corresponding subcarriers in two adjacent radar pulses; compensating the phase of the communication modulation information of each pulse based on a preset coherent threshold, so that the phase difference between the corresponding subcarriers of adjacent pulses is controlled within the preset threshold range, ensuring phase consistency during multi-pulse coherent accumulation; and simultaneously introducing the autocorrelation characteristics of the Gore-Ley complementary waveform to further suppress sidelobe interference during coherent accumulation and improve accumulation gain.

[0049] Furthermore, step 4 specifically involves: mapping the phase-calibrated communication modulation information onto the corresponding OFDM subcarriers, and generating each OFDM symbol through IFFT transformation, windowing processing, and digital-to-analog conversion; the windowing processing uses a Hanning window to reduce energy leakage at the subcarrier edges and further suppress ICI interference; combining the Ns OFDM symbols sequentially to form a single radar transmit pulse, and repeatedly generating M consecutive radar transmit pulses to obtain the optimized multi-pulse radar communication integrated signal.

[0050] Furthermore, in step 1, the baseband form expression of the multi-pulse OFDM radar-communication integrated signal is as follows: in, This refers to the pre-modulated communication modulation information on the m-th pulse, the n-th OFDM symbol, and the k-th subcarrier. For rectangular window functions, The pulse repetition period, For OFDM symbol period, For radar carrier frequency, The subcarrier spacing.

[0051] Furthermore, in step 2, the specific process of the ICI suppression coding is as follows:

[0052] S21. Divide the communication information sequence after the first pre-modulation into several coding blocks, each coding block containing L communication symbols;

[0053] S22. Insert pilot symbols at the beginning and end of each coding block. The pilot symbols adopt a known orthogonal sequence and are used for channel state estimation.

[0054] S23. Perform differential coding on the coding block after inserting the pilot to generate an ICI suppression coding sequence. The coding rate of differential coding is adaptively adjusted according to the number of subcarriers and the time-varying characteristics of the channel to ensure that the communication transmission rate is not affected while suppressing ICI interference.

[0055] Furthermore, in step 3, the specific process of phase calibration is as follows:

[0056] S31. Calculate the phase difference between the nth OFDM symbol and the premodulated communication information on the kth subcarrier in the mth pulse and the (m+1)th pulse. ;

[0057] S32, Preset coherent threshold The coherent threshold The value is determined based on the radar coherent accumulation gain requirement, and its range is 0.01π-0.05π.

[0058] S33, if Then, for the pre-modulated communication information on the nth OFDM symbol and the kth subcarrier in the (m+1)th pulse... Phase compensation is performed, and the compensation amount is... ;like Then keep constant;

[0059] S34. Repeat steps S31-S33 to complete the phase calibration between all adjacent pulses and obtain the phase-calibrated communication modulation information sequence.

[0060] Furthermore, in step 5, the performance verification specifically includes:

[0061] Radar detection accuracy verification: Calculate the ambiguity function of the optimized signal, detect the sidelobe level of the ambiguity function. If the sidelobe level is lower than the preset threshold, and the ranging accuracy error is ≤0.5m and the velocity accuracy error is ≤0.1m / s, then the radar detection accuracy requirements are met.

[0062] Communication transmission quality verification: Calculate the bit error rate (BER) of the communication signal. If the BER... If the signal is within acceptable limits, the communication transmission quality requirements are met; if any one of these requirements is not met, the coding rate, pilot insertion interval, or coherent threshold of the ICI suppression coding is adjusted, the signal is regenerated, and the verification is performed.

[0063] Compared with the prior art, the present invention has the following advantages:

[0064] This invention addresses the shortcomings of existing technologies in suppressing OFDM inter-carrier interference (ICI). Based on Gold sequence premodulation, it adds a secondary premodulation process of ICI suppression coding, combined with windowing techniques and pilot-assisted channel estimation methods. This effectively counteracts energy leakage between subcarriers caused by frequency offset, time-varying channels, and Doppler effects, significantly suppressing ICI interference, avoiding ambiguity function deterioration and waveform sidelobe rise, and greatly improving radar ranging and velocity measurement accuracy. Simultaneously, the ICI suppression coding employs an adaptive rate design, ensuring interference suppression while also considering communication transmission rate, thus solving the problem of balancing radar detection accuracy and communication rate in existing technologies.

[0065] This invention establishes an integrated signal model for multi-pulse OFDM radar communication. By using phase calibration technology to ensure the coherence between adjacent pulses and combining the autocorrelation characteristics of Gore-Ley complemented waveforms, it avoids the destruction of multi-pulse coherent accumulation by communication information, improves the coherent accumulation gain, and enhances the weak target detection performance. The phase calibration adopts an adaptive threshold design, which can be flexibly adjusted according to radar detection requirements, adapting to the weak target detection requirements in different scenarios and expanding the application range of the integrated system.

[0066] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for optimizing integrated radar and communication signals, characterized in that, Includes the following steps: Step 1: Determine the operating parameters of the integrated radar and communication system and establish a multi-pulse OFDM integrated radar and communication signal model; Step 2: Perform dual pre-modulation processing on the communication modulation information to reduce the impact of the communication information on the radar waveform; Step 3: Based on the multi-pulse coherent accumulation constraint, perform phase calibration on the pre-modulated communication modulation information sequence to ensure inter-pulse coherence; Step 4: Load the phase-calibrated communication modulation information onto the OFDM subcarrier to generate OFDM symbols, which are then used to form radar transmission pulses, thus completing the generation of the integrated multi-pulse radar communication signal. Step 5: Verify the performance of the generated optimized radar-communication integrated signal. If it meets the preset radar detection accuracy and communication transmission quality requirements, output the signal. If it does not meet the requirements, adjust the ICI suppression coding parameters in step S2 and the coherent threshold in step S3, and repeat steps 2-4 until the requirements are met.

2. The method for optimizing radar-communication integrated signals according to claim 1, characterized in that, In step 1, the operating parameters include the radar transmit pulse repetition frequency (PRF), the number of OFDM symbols Ns in each radar transmit pulse, the number of OFDM subcarriers Nc, the subcarrier spacing Δf, the communication modulation method, and the radar detection range. The multi-pulse OFDM radar-communication integrated signal model includes M continuously transmitted radar pulses, each pulse containing Ns OFDM symbols. Each OFDM symbol is composed of Nc subcarriers, and each subcarrier is loaded with communication modulation information, while ensuring the coherence constraint between adjacent pulses.

3. The method for optimizing integrated radar and communication signals according to claim 1, characterized in that, In step 2, the dual premodulation process specifically involves: firstly, using a Gold sequence to premodulate the original communication modulation information to reduce the fundamental impact of the communication information on the radar ambiguity function; then, using ICI suppression coding to premodulate the communication information after the first premodulation. The ICI suppression coding adopts a pilot-assisted differential coding method, which achieves channel state estimation by inserting known pilot symbols, and at the same time utilizes the redundancy characteristics of differential coding to reconstruct the signal, offset the energy leakage between subcarriers, suppress ICI interference, and obtain the premodulated communication modulation information sequence.

4. The method for optimizing integrated radar and communication signals according to claim 1, characterized in that, In step S3, the phase calibration specifically involves: calculating the phase difference between the corresponding OFDM symbols and the pre-modulated communication information on the corresponding subcarriers in two adjacent radar pulses; compensating the phase of the communication modulation information of each pulse based on a preset coherent threshold, so that the phase difference between the corresponding subcarriers of adjacent pulses is controlled within the preset threshold range, ensuring phase consistency during multi-pulse coherent accumulation; and introducing the autocorrelation characteristics of the Gore-Ley complementary waveform to further suppress sidelobe interference during coherent accumulation and improve accumulation gain.

5. The method for optimizing integrated radar and communication signals according to claim 1, characterized in that, Step 4 specifically involves: mapping the phase-calibrated communication modulation information onto the corresponding OFDM subcarriers, and generating each OFDM symbol through IFFT transformation, windowing processing, and digital-to-analog conversion; the windowing processing uses a Hanning window to reduce energy leakage at the subcarrier edges and further suppress ICI interference; combining the Ns OFDM symbols sequentially to form a single radar transmit pulse, and repeating this process to generate M consecutive radar transmit pulses to obtain the optimized multi-pulse radar communication integrated signal.

6. The method for optimizing integrated radar and communication signals according to claim 1, characterized in that, In step 1, the baseband form expression of the multi-pulse OFDM radar-communication integrated signal is as follows: in, This refers to the pre-modulated communication modulation information on the m-th pulse, the n-th OFDM symbol, and the k-th subcarrier. For rectangular window functions, The pulse repetition period, For OFDM symbol period, For radar carrier frequency, The subcarrier spacing.

7. The method for optimizing integrated radar and communication signals according to claim 1, characterized in that, In step 2, the specific process of the ICI suppression coding is as follows: S21. Divide the communication information sequence after the first pre-modulation into several coding blocks, each coding block containing L communication symbols; S22. Insert pilot symbols at the beginning and end of each coding block. The pilot symbols adopt a known orthogonal sequence and are used for channel state estimation. S23. Perform differential coding on the coding block after inserting the pilot to generate an ICI suppression coding sequence. The coding rate of differential coding is adaptively adjusted according to the number of subcarriers and the time-varying characteristics of the channel to ensure that the communication transmission rate is not affected while suppressing ICI interference.

8. The method for optimizing integrated radar and communication signals according to claim 1, characterized in that, In step 3, the specific process of phase calibration is as follows: S31. Calculate the phase difference between the nth OFDM symbol and the premodulated communication information on the kth subcarrier in the mth pulse and the (m+1)th pulse. ; S32, Preset coherent threshold The coherent threshold The value is determined based on the radar coherent accumulation gain requirement, and its range is 0.01π-0.05π. S33, if Then, for the pre-modulated communication information on the nth OFDM symbol and the kth subcarrier in the (m+1)th pulse... Phase compensation is performed, and the compensation amount is... ;like Then keep constant; S34. Repeat steps S31-S33 to complete the phase calibration between all adjacent pulses and obtain the phase-calibrated communication modulation information sequence.

9. The method for optimizing integrated radar and communication signals according to claim 1, characterized in that, In step 5, the performance verification specifically includes: a. Radar detection accuracy verification: Calculate the ambiguity function of the optimized signal, detect the sidelobe level of the ambiguity function. If the sidelobe level is lower than the preset threshold, and the ranging accuracy error is ≤0.5m and the velocity accuracy error is ≤0.1m / s, then the radar detection accuracy requirements are met. b. Communication transmission quality verification: Calculate the bit error rate of the communication signal. If the bit error rate is ≤10⁻ 6 If the signal is within acceptable limits, the communication transmission quality requirements are met; if any one of these requirements is not met, the coding rate, pilot insertion interval, or coherent threshold of the ICI suppression coding is adjusted, the signal is regenerated, and the verification is performed.

Images