Method for synthesizing broadband detection waveform by using segmented communication signals

Abstract

The invention belongs to the technical field of radar and communication signal processing, and particularly relates to a method for synthesizing a broadband detection waveform by using segmented communication signals. The method comprises the steps of setting sub-waveform parameters and analyzing communication performance, then performing segmented frequency shift superposition on sub-waveforms in a time domain to obtain broadband detection waveforms, performing spectrum analysis, finally performing simulation to obtain echoes of a point target, and performing pulse compression and demodulation processing. According to the invention, overlapping of adjacent frequency bands is controlled through segmented splicing, so that the spectrum utilization efficiency is improved; a final result shows that the waveform designed by the method can meet the performance requirements of communication and detection, and the purposes of communication and detection are achieved at the same time.

Description

Technical Field

[0001] This invention belongs to the field of radar and communication signal processing, specifically, it relates to a method for synthesizing broadband detection waveforms using segmented communication signals. Background Technology

[0002] With the development of radar and communication fusion systems, traditional radar waveforms have gradually revealed many shortcomings in multi-functional integrated scenarios. Although classic radar waveforms such as linear frequency modulation (LFM) and stepped frequency have good range resolution and anti-interference capabilities, they have the following problems: strong waveform enclosure, traditional radar waveforms cannot carry communication information, and low resource utilization; low spectrum efficiency, making it difficult to share spectrum resources with modern communication systems; and poor interoperability, making it difficult to be compatible with multiple protocols and platforms in multi-user, multi-platform scenarios.

[0003] On the other hand, while modern communication systems (such as 5G, Wi-Fi 6 / 7, and UWB) employ waveforms like Orthogonal Frequency Division Multiplexing (OFDM), Multi-Carrier Modulation (MCM), and Spread Spectrum, which offer high spectral efficiency, low bit error rate, and good multiple access performance, these waveforms are inherently designed for data transmission and have the following limitations in target detection and parameter estimation: limited bandwidth (communication waveforms typically operate with very small bandwidths, failing to provide the high range resolution required by radar); complex structure (inter-carrier interference and multipath effects introduce complex background noise during radar processing); and low target echo utilization (the communication frame structure exhibits randomness and uncertainty in echo response, affecting detection stability).

[0004] In recent years, as Joint Radar-Communication (JRC) has become an important research direction for next-generation intelligent sensing systems, the industry has begun to explore using communication signals themselves as radar waveforms to achieve spectrum resource sharing, functional coupling, and device integration. Typical methods include: directly using communication signals as radar transmission waveforms, such as WiFi-Radar and 5G-Sensing; superimposing radar components on communication signals, such as joint frame structures; and joint designs based on waveform optimization, such as Pareto optimal waveform matching. However, these methods still have the following shortcomings: the bandwidth of the synthesized waveform is limited, and the range resolution is difficult to meet the requirements of fine target recognition; the subcarriers or subframes are highly independent, and the phase of the waveform after splicing is discontinuous, affecting the output of matched filters; the communication protocol has a high degree of coupling, making it difficult to flexibly adapt to various standard scenarios. Therefore, there is an urgent need for a broadband waveform construction method based on communication signal segment splicing. This method should possess the following advantages: it can combine and splice multiple segments or frequency bands in the communication signal to form a controllable, high-quality broadband detection waveform; it maintains the integrity of the communication information structure and does not affect the bit error rate performance; and it constructs high-resolution, phase-continuous broadband radar waveforms through frequency shift modulation, windowing processing, and precise splicing. It can be widely applied in emerging scenarios such as intelligent connected vehicles, vehicle-mounted millimeter-wave radar, air-to-ground fusion communication, and edge sensing devices. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for synthesizing broadband detection waveforms using segmented communication signals. This invention combines communication and radar detection waveforms, achieving simultaneous information transmission in communication tasks and target detection in detection tasks. Furthermore, this invention improves spectrum utilization efficiency by controlling the overlap of adjacent frequency bands through segmented splicing. The technical solution of this invention is described in detail below.

[0006] This invention provides a method for synthesizing broadband probe waveforms using segmented communication signals. It combines the requirements of both communication and probe missions, utilizing multiple narrowband communication signals to synthesize a broadband probe waveform, thus achieving a broadband waveform design that simultaneously meets the performance requirements of both communication and probe missions. The specific steps are as follows:

[0007] Step 1: Set the sub-waveform parameters to ensure that the sub-waveform meets the communication performance requirements; the sub-waveform parameters include the sub-waveform type, the number of sub-waveform symbols, the duration, and the sampling rate;

[0008] Step 2: Set the broadband waveform parameters according to the radar detection requirements. The broadband waveform parameters include frequency range, frequency interval, time width, and range resolution.

[0009] Step 3: Segment and frequency shift the sub-waveform to synthesize a broadband probe waveform;

[0010] Divide the sub-waveform into Section, No. The time range of the segment is , The frequency difference between two adjacent carrier segments is Then the bandwidth of the broadband signal is Broadband waveform is represented as , , The starting frequency, and These are the I and Q baseband signals, respectively. For the first The sub-waveform of the sub-time period is composed of two positive traffic channels, I and Q;

[0011] Step 4: Calculate broadband echo based on point target;

[0012] The echo is represented as: , In the time domain, this manifests as a two-way delay in transmitting a broadband signal, where, The number of point targets. For the first The scattering intensity of a point target, For the first The straight-line slant range of a point target in the radar line-of-sight direction;

[0013] Step 5: Perform coherent demodulation on the echo and pulse compression to obtain the transmitted symbol information and the target one-dimensional range image information, respectively.

[0014] In this invention, in step one, the sub-waveform type is QPSK, BPSK, or QAM signal.

[0015] In this invention, the formula for calculating distance resolution in step two is as follows: , in, At the speed of light, This refers to the signal bandwidth.

[0016] In this invention, in step five, the echo signal is multiplied with the orthogonal reference signal, passed through a low-pass filter, and then sampled and decided to recover the baseband signal; the echo signal is convolved with the deconvolution conjugate of the reference signal in the time domain or multiplied with the conjugate of the reference signal in the frequency domain and returned to the time domain to obtain the detected one-dimensional range image.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1) The method of the present invention can combine and splice multiple segments or frequency bands in a communication signal to form a controllable, high-quality broadband detection waveform;

[0019] 2) The method of the present invention maintains the integrity of the communication information structure and does not affect the bit error rate performance. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a method for synthesizing broadband probe waveforms using segmented communication signals.

[0022] Figure 2 The results are from a broadband signal simulation.

[0023] Figure 3 This is the simulation result of the range image of a single target.

[0024] Figure 4 The results are simulations of baseband signal recovery for a single target.

[0025] Figure 5 The result is a simulation of the distance between two target points.

[0026] Figure 6 The simulation results are for recovering the baseband signal of two target points. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below through specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a method for synthesizing broadband probe waveforms using segmented communication signals, such as... Figure 1 As shown, the specific steps are as follows:

[0029] Step 1: Set sub-waveform parameters. Based on communication requirements, set parameters such as sub-waveform type (e.g., QPSK), number of sub-waveform symbols, duration, and sampling rate to ensure the sub-waveform meets communication performance requirements. The signal form of QPSK is: (1), in, For signal carrier frequency, For the first The phase angle obtained by mapping group symbols and These are the I and Q baseband signals, respectively.

[0030] Step 2: Set the broadband waveform parameters. Based on the detection requirements, set the broadband waveform parameters, including frequency range, frequency interval, and time width. For radar target detection, a certain range resolution must be met. The formula for calculating range resolution is as follows: (2), At the speed of light, This refers to the signal bandwidth.

[0031] Step 3: Segment and frequency shift the sub-waveform to synthesize a broadband probe waveform. The sub-waveform is divided into... Section, No. The time range of the segment is , The frequency difference between two adjacent carrier segments is Then the bandwidth of the broadband signal is A broadband waveform can be represented as... ,in: (3), This is the starting frequency.

[0032] Step 4: Calculate the broadband echo based on the point target. The echo can be represented as: (4), In the time domain, this manifests as a two-way delay in transmitting a broadband signal, where, The number of point targets. For the first The scattering intensity of a point target, For the first The slant range of a point target in the radar line of sight.

[0033] Step 5: Perform coherent demodulation and pulse compression on the echo to obtain the transmitted symbol information and the target's one-dimensional range image information. Multiply the echo signal with the orthogonal reference signal, pass it through a low-pass filter, and then perform sampling and decision to recover the baseband signal. The detected one-dimensional range image can be obtained by convolving the echo signal with the deconvolution conjugate of the reference signal in the time domain or by multiplying the echo signal with the reference signal's conjugate in the frequency domain and returning the result to the time domain.

[0034] The following are specific examples.

[0035] Example 1

[0036] Assuming the radar operates at a starting frequency of 1 GHz, a bandwidth of 75 MHz, and a corresponding range resolution of 2 m, each pulse carries 400 communication symbols with a duration of 0.4 seconds. The sampling rate is 5 GHz, the sub-waveform is divided into 100 segments, and the communication modulation method is QPSK. The target scene is a single point target, 100 m away from the radar, with a scattering intensity of 1. 20 dB of additive white Gaussian noise has been added. Figure 2 The baseband signal to be transmitted and the broadband probe waveform and its spectrum are given. Figure 3 This invention utilizes the broadband detection waveform synthesized from segmented communication signals to obtain a one-dimensional range profile when detecting a single-point target. Figure 3 It can be seen that a distinct and concentrated main peak appears at the actual target distance of 100 m, and the position of the main peak is highly consistent with the actual distance of the preset point target. No significant false peaks or sidelobe interference appear in other distance units. The results show that the broadband detection waveform formed by segmenting and splicing communication signals maintains good coherence in both the time and frequency domains; the synthesized equivalent bandwidth effectively improves the range resolution, enabling accurate positioning of a single point target at a range resolution of 2 m; even with the addition of 20 dB additive white Gaussian noise, the main peak of the range image remains clearly distinguishable, indicating that this method has good noise resistance and stable detection performance. Therefore, Figure 3 This verifies that the broadband detection waveform designed in this invention has accurate range positioning capability in single-point target scenarios, meeting the basic performance requirements of radar detection. Figure 4 This represents the baseband communication signal recovery result obtained after coherent demodulation and sampling decision of the echo signal in a single-point target scenario. From... Figure 4 It can be seen that the baseband signal symbol sequence recovered after demodulation is consistent with the original communication symbols at the transmitting end, and no obvious symbol misjudgment or phase reversal phenomenon is observed. This indicates that: after the segmented communication signal is frequency-shifted and spliced ​​and participates in radar detection, its original communication modulation structure is not destroyed; the radar echo processing process does not have an irreversible impact on the demodulation of communication information; and the proposed broadband waveform can achieve reliable transmission of communication information while completing target detection. Figure 4 The results further verify the feasibility and effectiveness of the method of the present invention in the integrated communication and detection scenario, proving that the waveform can simultaneously meet the bit error rate requirements of the communication system and the detection requirements of the radar system.

[0037] Example 2

[0038] Assuming the radar operates at a starting frequency of 1 GHz, a bandwidth of 75 MHz, and a corresponding range resolution of 2 m, each pulse carries 400 communication symbols with a duration of 0.4 seconds. The sampling rate was 5 GHz, the sub-waveform was divided into 100 segments, and the communication modulation method was QPSK. The target scenario consisted of two point targets 20 m apart, 100 m and 120 m away from the radar respectively, with a scattering intensity of 1 for both. 20 dB of additive white Gaussian noise was added. Figure 5 This describes the one-dimensional distance image obtained using the method of this invention when two point targets exist. Figure 5 It can be seen that two clear peaks appear at distances of 100 m and 120 m from the radar, with an interval of approximately 20 m between the two peaks, perfectly consistent with the actual distance interval between the two preset target points. This result indicates that the equivalent bandwidth of the synthetic broadband detection waveform can provide sufficient range resolution; in multi-target scenarios, the echoes of different targets can be effectively distinguished without main lobe merging or range ambiguity; and the segmented frequency shift synthesis method does not introduce additional false targets or severe sidelobe interference. Therefore, Figure 5 The method of the present invention has been verified to maintain good range resolution performance in multi-point target scenarios, and is suitable for fine detection tasks in complex target environments. Figure 6 This represents the baseband communication signal recovery result obtained after demodulating the echo signal in a two-point target scenario. From... Figure 6 It can be seen that despite the superposition of multiple target echoes and multipath propagation effects, the recovered baseband signal remains consistent with the transmitting end communication symbols after coherent demodulation and sampling decision processing. This demonstrates that: superimposed echoes generated by multiple targets do not destroy the orthogonality and modulation structure of the communication signal; the waveform proposed in this invention can still stably carry communication information in a multi-target scattering environment; and this method has the ability to simultaneously realize communication and sensing functions in complex detection scenarios. Figure 6 The results show that the broadband detection waveform proposed in this invention can still ensure that the communication performance is not degraded under multi-point target conditions, further demonstrating the practical value of this method in radar communication fusion applications.

Claims

1. A method for synthesizing broadband probe waveforms using segmented communication signals, characterized in that, Combining communication and detection The two tasks require the synthesis of a broadband detection waveform from multiple narrowband communication signals to achieve a broadband waveform design that simultaneously meets the requirements of both communication and detection performance. The specific steps are as follows: Step 1: Set the sub-waveform parameters to ensure that the sub-waveform meets the communication performance requirements; the sub-waveform parameters include the sub-waveform type, the number of sub-waveform symbols, the duration, and the sampling rate; Step 2: Set the broadband waveform parameters according to the radar detection requirements. The broadband waveform parameters include frequency range, frequency interval, time width, and range resolution. Step 3: Segment and frequency shift the sub-waveform to synthesize a broadband probe waveform; Divide the sub-waveform into Section, No. The time range of the segment is , The frequency difference between two adjacent carrier segments is Then the bandwidth of the broadband signal is Broadband waveform is represented as , , The starting frequency, and These are the I and Q baseband signals, respectively. For the first The sub-waveform of the sub-time period is composed of two positive traffic channels, I and Q; Step 4: Calculate broadband echo based on point target; The echo is represented as: ， In the time domain, this manifests as a two-way delay in transmitting a broadband signal, where, The number of point targets. For the first The scattering intensity of a point target, For the first The straight-line slant range of a point target in the radar line-of-sight direction; Step 5: Perform coherent demodulation on the echo and pulse compression to obtain the transmitted symbol information and the target one-dimensional range image information, respectively.

2. The method for synthesizing broadband probe waveforms using segmented communication signals according to claim 1, characterized in that, In step one, the sub-waveform category is QPSK, BPSK, or QAM signal.

3. The method for synthesizing broadband probe waveforms using segmented communication signals according to claim 1, characterized in that, In step two, the formula for calculating distance resolution is as follows: ， in, At the speed of light, This refers to the signal bandwidth.

4. The method for synthesizing broadband probe waveforms using segmented communication signals according to claim 1, characterized in that, In step five, the echo signal is multiplied with the orthogonal reference signal, passed through a low-pass filter, and then sampled and decided to recover the baseband signal. The echo signal is then convolved with the deconvolution conjugate of the reference signal in the time domain or multiplied with the conjugate of the reference signal in the frequency domain and returned to the time domain to obtain the detected one-dimensional range image.

Images