Synaesthesia integrated signal design and beamforming method based on time-delay alignment modulation

Abstract

The present invention discloses a method for integrated synaesthesia signal design and beamforming based on delay alignment modulation, including: obtaining the number of delay-resolvable paths, the delay and gain vector of each path of the communication user channel according to the channel impulse response of the communication user, and obtaining the angle information of the perceived target according to the angle search; within the coherence time, the transmitter introduces the corresponding delay pre-compensation according to the delay of each path of the communication user channel, and saves the generated data stream for radar perception; the transmitter designs the communication perception integrated transmission beamforming vector for each path according to the channel gain vector of each path of the communication user and the perceived target angle, and saves the result for radar perception. The inter-code interference of the communication user is eliminated by the method of path-by-path zero-forcing beamforming, the communication signal-to-noise ratio is maximized, and the echo signal-to-noise ratio of the perceived target at a specific angle is made greater than the signal-to-noise ratio threshold. The present invention realizes single-carrier low peak-to-average ratio inter-code interference-free communication and efficient perception.

Description

Technical Field

[0001] The present invention belongs to the field of 6G wireless access network evolution and communication perception integrated signal design and beamforming, and in particular to a synaesthesia integrated signal design and beamforming method based on delay alignment modulation. Background Art

[0002] With the development of wireless communications, more and more wireless access devices have made spectrum resources increasingly scarce. Integrated sensing and communication (ISAC) has gradually become an important trend and research hotspot in the future development of wireless networks. This technology can efficiently utilize wireless resources, achieve reciprocity between communication and perception, and use almost ubiquitous communication networks for perception to build a bridge between the physical world and the digital world. For ISAC research, one of the key issues is how to design signals and beamforming methods that are suitable for both communication and perception, so as to obtain good communication and perception performance at the same time.

[0003] To achieve this goal, early research focused on radar-centric methods, in which the communication function complements radar perception and achieves communication by inserting communication symbols into the radar waveform without affecting its perception performance. However, the communication rate of such methods is low, and the communication symbols based on radar waveform modulation are not well suited for communication in complex multipath environments. Another research idea is to achieve perception based on communication signals, among which the typical method is ISAC based on OFDM (orthogonal frequency division multiplexing). On the one hand, OFDM is widely used in communication standards, has good resistance to multipath fading and inter-code interference, and is the mainstream transmission technology for broadband communication. On the other hand, radar perception based on OFDM can use FFT (fast Fourier transform) and its inverse transform to achieve low-complexity radar perception signal processing. However, OFDM signals have high PAPR (peak-to-average-power ratio), phase noise sensitivity, and poor anti-Doppler capability, which to some extent affect the communication and perception performance of OFDM, especially ISAC in long-distance and high-speed mobile scenarios. In order to solve the above problems faced by OFDM, researchers have proposed modulation technologies such as SC-FDMA (single-carrier frequency division multiple access) and OTFS (orthogonal time-frequency space). However, such technologies require the communication receiving end to perform complex channel equalization, or require the transmitting and receiving end to perform complex signal processing, which increases the signal processing overhead. Summary of the invention

[0004] The purpose of the present invention is to provide a synaesthesia integrated signal design and beamforming method based on delay alignment modulation to solve the technical problems of excessive peak-to-average power of signals or the need for complex communication channel equalization in a communication perception integrated system in a multipath environment.

[0005] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0006] A synaesthesia integrated signal design and beamforming method based on time delay alignment modulation includes the following steps:

[0007] Step 1: According to the impulse response of the communication user channel, the number of delay-resolvable paths L, the delay and gain vector of each path of the communication user channel are obtained, and the angle information of the perceived target is obtained according to the radar angle search;

[0008] Step 2: Within a coherent time, the transmitter introduces corresponding delay pre-compensation to the data stream to be sent according to the path delays of the communication user channel, and saves the generated L-path data streams for radar perception;

[0009] Step 3: The transmitter designs a communication-sensing integrated transmission beamforming vector for each path according to the channel gain vector of each path of the communication user and the perception target angle, and saves the result for radar perception; specifically, the following steps are included: using the path-by-path zero-forcing beamforming method to eliminate the inter-symbol interference of the communication user, maximize the communication signal-to-noise ratio, and ensure that the echo signal-to-noise ratio at a specific perception target angle is greater than the signal-to-noise ratio threshold required for perception;

[0010] Step 4: Generate and send a delay-aligned modulation signal according to the data stream generated in step 2 and the transmit beamforming vector generated in step 3;

[0011] Step 5: The communication user receives the signal and demodulates the communication symbol using a low-complexity single-carrier communication signal processing method;

[0012] Step 6: The radar receiver generates a two-dimensional matched filter for each delay and Doppler interval according to the data stream generated in step 2 and the transmit beamforming vector generated in step 3;

[0013] Step 7: The radar receiver performs two-dimensional matched filtering on the echo signal received within a coherent time according to the matched filter generated in step 6, and performs a maximum value search on the response result to find the time delay and Doppler frequency corresponding to its peak value, and finally obtains the distance and speed of the target.

[0014] Furthermore, in step 1, each delay-resolvable path includes multiple sub-paths with different departure angles. For sensing, the echo signal of the scatterer in the communication channel is suppressed by the clutter elimination technology at the radar receiving end.

[0015] Furthermore, in step 3, the beamforming method using path-by-path zero forcing specifically includes the following steps: requiring the beamforming vector of each path to be located in the null space formed by other paths, and needing to meet the minimum signal-to-noise ratio requirement at the perceived target angle.

[0016] Furthermore, in step 4, a protection interval is set for the transmitted signal in each channel coherent time block to avoid interference between different coherent time blocks. The duration of the protection interval needs to take into account the requirements of communication and perception at the same time, and the maximum delay of all channel coherent time blocks and the maximum value of the echo delay of the farthest perceived target are taken.

[0017] Furthermore, in step 6, the delay-Doppler frequency interval where the target may exist is divided into sub-intervals according to the delay and Doppler frequency resolution, and for each sub-interval, a two-dimensional matched filter is generated according to the stored L data streams and the transmit beamforming vector.

[0018] Furthermore, in step 7, for each coherent time, the radar receiver receives the echo signal and performs the following processing: first, the echo signal within the protection interval length is removed to avoid interference between echo signals of different coherent time blocks, and the remaining echo signal is subjected to two-dimensional matched filtering according to the two-dimensional matched filter generated in step 6, and a maximum value search is performed to find the time delay and Doppler frequency corresponding to the peak value, thereby determining the distance and speed of the target.

[0019] The communication perception integrated signal design and beamforming method based on delay alignment modulation of the present invention has the following advantages:

[0020] 1. This method makes full use of the sparsity of the channel and the spatial freedom of the large-scale antenna array. Through the method of delay pre-compensation at the transmitting end and path-by-path zero-forcing beamforming, it can realize single-carrier communication without inter-code interference in a multipath environment. At the same time, when designing the transmit beamforming vector, the radar perception performance is fully considered to ensure that the signal-to-noise ratio at the perceived target angle is greater than the signal-to-noise ratio threshold required for perception.

[0021] 2. This method is based on delay alignment modulation and can realize the integration of single-carrier communication and perception in complex multipath environments, greatly reducing the PAPR of the signal and improving the system's ability to resist Doppler frequency deviation, so that it can obtain better communication and perception performance in long-distance and high-speed scenarios.

[0022] 3. This method is based on delay alignment modulation. Only one guard interval needs to be inserted in each channel coherence time to avoid interference between different coherence time blocks. Compared with OFDM transmission, this method reduces the communication overhead and improves the spectrum efficiency of communication. On the other hand, since the number of guard intervals in this method is much smaller than that of OFDM, this method can obtain a higher perceived signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a single-station communication perception integrated system in a multipath environment provided by an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of a signal processing flow of a communication-aware integrated transmitter provided in an embodiment of the present invention;

[0025] Figure 3 The present invention is a schematic diagram of a radar receiver receiving signal processing flow chart provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a communication perception integrated signal design and beamforming method based on delay alignment modulation of the present invention in conjunction with the accompanying drawings.

[0027] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0028] Figure 1 This is a scenario of single-station communication perception integration in a multipath environment according to an embodiment, in which a communication perception integrated transmitter and a radar receiver are integrated into one device, with multiple transmitting antenna units and one receiving antenna unit, which can simultaneously send signals and receive echoes reflected by the target. On the other hand, the echo of the scatterer can be suppressed by radar clutter elimination technology, so as not to affect target perception.

[0029] Figure 2 It is a signal processing flow of the transmitting end based on delay alignment modulation and a beamforming method for integrated communication and perception shown in the embodiment. According to the channel gain vector of each path of the communication user channel and the perception target angle, a communication and perception integrated transmission beamforming vector is designed for each path, and the result is saved for radar perception. Specifically, the path-by-path zero-forcing beamforming method is used to eliminate the inter-code interference at the communication receiving end, maximize the communication signal-to-noise ratio, and at the same time ensure that the echo signal-to-noise ratio at a specific perception target angle is greater than the signal-to-noise ratio threshold required for perception.

[0030] Figure 3 The figure is a schematic diagram of the radar receiver receiving signal processing flow according to the embodiment. The radar receiver generates a two-dimensional matched filter for each delay and Doppler interval according to the stored L-channel data stream and the transmit beamforming vector. For a coherent time, after the radar receiver receives the echo signal, it performs the following processing: first, the echo signal within the guard interval length is removed to avoid interference between echo signals in different coherent times, and the remaining echo signal is subjected to two-dimensional matched filtering, and a maximum value search is performed to find the delay and Doppler frequency corresponding to the peak, thereby determining the distance and speed of the target.

[0031] Based on the above definition, the specific implementation steps of the embodiment can be summarized as follows:

[0032] Step 1: Parameter initialization. According to the channel impulse response of the communication user, obtain the number of delay-resolvable paths L and the delay of each path of the channel. and the channel gain vector And according to the radar angle search, the angle information θ of the perceived target is obtained.

[0033] Step 2: Calculate the maximum delay of the channel Calculate the delay precompensation κ of each path l =n max -n l ,l=1,…,L; introduce the corresponding delay pre-compensation for the data stream to be sent, and generate a matrix consisting of L data streams in N is the length of the transmitted signal, and the matrix is ​​saved for radar perception;

[0034] Step 3: According to the communication user channel gain vector Calculate the null space projection matrix of each channel in I M is an M-order unit matrix, where M is the number of transmitting antennas. Initialize the beamforming vector to be designed And set the perceptual signal-to-noise ratio threshold γ th . Maximize the communication signal-to-noise ratio while ensuring that the perceived signal-to-noise ratio is not less than γ under the condition that it is not greater than the average power P of the transmitted signal. th , solve the optimal beamforming vector, as shown below

[0035]

[0036]

[0037] in is the direction vector of the transmitting antenna at the sensing target angle. Generate transmit beamforming matrix where f l =Q l b l ,l=1,…,L, and save it for radar perception reception.

[0038] Step 4: Delay data stream generated according to step 2 and the transmit beamforming matrix F generated in step 3 to generate a delay-aligned modulation signal and send.

[0039] Step 5: The communication user receives the signal and demodulates the communication symbol using a simple single-carrier communication signal processing method.

[0040] Step 6: The radar receiver generates data streams according to steps 2 and 3. And the transmit beamforming matrix F, a two-dimensional matched filter is generated for each delay and Doppler interval, as shown in the following formula

[0041]

[0042] Where P is the number of delay intervals, Q is the number of Doppler intervals, (n p ,f q ), p=0,…P-1,q=0,…,Q-1 are the delay and Doppler frequency corresponding to the pth delay interval and the qth Doppler interval respectively, is the Doppler frequency estimation vector.

[0043] Step 7: After receiving the echo signal within each coherence time, the radar receiver performs the following processing: first, the echo signal within the guard interval length is removed to avoid interference between echo signals within different coherence times; the remaining echo signal is subjected to two-dimensional matched filtering using the two-dimensional matched filter designed in step 6, and a maximum value search is performed to find the time delay corresponding to the peak value. and Doppler frequency Right now in is the response output of the two-dimensional matched filter, The received echo signal is used to estimate the distance and speed of the target.

[0044] The above method utilizes the sparsity of the channel and the spatial freedom of the large-scale antenna array, and can realize single-carrier inter-code interference-free communication in a multipath environment through the method of delay pre-compensation at the transmitting end and path-by-path zero-forcing beamforming (steps 2 and 3). At the same time, when designing the transmit beamforming vector, the radar perception performance is fully considered to ensure that the signal-to-noise ratio at the perceived target angle is greater than the signal-to-noise ratio threshold required for perception (step 3). In particular, this method is based on delay alignment modulation, and only needs to insert a guard interval in each channel coherence time to avoid interference between different coherence time blocks. Compared with OFDM transmission, this method reduces the communication overhead and improves the spectrum efficiency of communication. On the other hand, since the number of guard intervals in this method is much smaller than that of OFDM, this method can obtain a higher perceived signal-to-noise ratio (step 7).

[0045] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A synaesthesia integrated signal design and beamforming method based on delay alignment modulation, characterized in that: The following steps are involved: Step 1: Parameter initialization: According to the channel impulse response of the communication user, obtain the number of delay-resolvable paths L and the delay of each path of the channel. and the channel gain vector And according to the radar angle search, the angle information θ of the perceived target is obtained; Step 2: Within a coherent time, the transmitter calculates the maximum delay of the channel based on the delay of each path of the communication user channel. Calculate the delay precompensation κ of each path l =n max -n l ,l=1,…,L; introduce the corresponding delay pre-compensation for the data stream to be sent, and generate a matrix consisting of L data streams in N is the length of the transmitted signal, and the matrix is ​​saved for radar perception; Step 3: The transmitter designs a communication-sensing integrated transmission beamforming vector for each path according to the channel gain vector of each communication user path and the perception target angle, and saves the result for radar perception; Specifically, the following steps are included: using the path-by-path zero-forcing beamforming method to eliminate the inter-code interference of the communication user; according to the communication user channel gain vector Calculate the null space projection matrix of each channel in I M is an M-order unit matrix, where M is the number of transmitting antennas; initialize the beamforming vector to be designed And set the perceptual signal-to-noise ratio threshold γ th ; Maximize the communication signal-to-noise ratio while ensuring that the perceived signal-to-noise ratio is not less than γ under the condition that it is not greater than the average power P of the transmitted signal th , solve the optimal beamforming vector, as shown below in is the direction vector of the transmitting antenna at the sensing target angle; according to the above formula Generate transmit beamforming matrix where f l =Q l b l ,l=1,…,L, and save it for radar perception reception; Step 4: Delay data stream generated according to step 2 and the transmit beamforming matrix F generated in step 3 to generate a delay-aligned modulation signal and send; Step 5: The communication user receives the signal and demodulates the communication symbol using a low-complexity single-carrier communication signal processing method; Step 6: The radar receiver generates data streams according to steps 2 and 3. And the transmit beamforming matrix F, a two-dimensional matched filter is generated for each delay and Doppler interval, as shown in the following formula Where P is the number of delay intervals, Q is the number of Doppler intervals, (n p ,f q ), p=0,…P-1,q=0,…,Q-1 are the delay and Doppler frequency corresponding to the pth delay interval and the qth Doppler interval respectively, is the Doppler frequency estimation vector; Step 7: The radar receiver performs two-dimensional matched filtering on the echo signal received within a coherent time according to the matched filter generated in step 6, and performs a maximum value search on the response result to find out the time delay and Doppler frequency corresponding to the peak value, and finally obtains the distance and speed of the target; For each coherence time, after the radar receiver receives the echo signal, it performs the following processing: first, the echo signal within the guard interval length is removed to avoid interference between echo signals in different coherence times, and the remaining echo signal is subjected to two-dimensional matched filtering according to the two-dimensional matched filter designed in step 6, and a maximum value search is performed to find the delay corresponding to the peak value. and Doppler frequency Right now in is the response output of the two-dimensional matched filter, The received echo signal is used to estimate the distance and speed of the target.

2. The synaesthesia integrated signal design and beamforming method based on delay alignment modulation according to claim 1 is characterized in that: In step 1, each delay-resolvable path contains multiple sub-paths with different departure angles; for perception, the echo signal of the scatterer in the communication channel is suppressed by the clutter elimination technology at the radar receiving end.

3. The synaesthesia integrated signal design and beamforming method based on delay alignment modulation according to claim 1 is characterized in that: In step 3, the method of using path-by-path zero-forcing beamforming specifically includes the following steps: requiring the beamforming vector of each path to be located in the null space formed by other paths, and needing to meet the minimum signal-to-noise ratio requirement at the perceived target angle.

4. The synaesthesia integrated signal design and beamforming method based on delay alignment modulation according to claim 1 is characterized in that: In step 4, a guard interval is set for the transmitted signal in each channel coherent time block to avoid interference between different coherent time blocks. The duration of the guard interval needs to take into account the requirements of both communication and perception, and the maximum delay of all channel coherent time blocks and the maximum value of the echo delay of the farthest perceived target are taken.

5. The synaesthesia integrated signal design and beamforming method based on delay alignment modulation according to claim 1 is characterized in that: In step 6, the predetermined perceived delay-Doppler frequency interval is divided into sub-intervals according to the delay and Doppler frequency resolution, and for each sub-interval, a two-dimensional matched filter is generated according to the stored L data streams and the transmit beamforming vector.

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