Radar sensing method and system based on near-field beam splitting

Abstract

The invention discloses a radar sensing method and system based on near-field beam splitting. The method comprises the following steps: determining a target distance based on a radar transmitting signal and an echo signal; determining a preliminary target angle according to the phase difference of the multi-antenna receiving signals; then, a near-field codebook is constructed based on the initial target angle, and beam splitting caused by frequency deviation is compensated by adjusting delay parameters; and meanwhile, a beam focusing vector is controlled to be generated, a pilot signal is transmitted, a feedback signal is received, and an optimal angle is determined through energy maximization search according to the feedback signal. According to the method, the number of detection beams is reduced by adopting the near-field beam splitting effect, the cost is reduced, meanwhile, beam training is performed after radar sensing, the pilot frequency overhead can be effectively reduced, and the communication rate can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of radar perception and wireless communication fusion, and more specifically to a radar perception method and system based on near-field beam splitting. More specifically, it relates to an integrated system design for broadband very large-scale multiple-input multiple-output (XL-MIMO) systems that utilizes the near-field beam splitting effect to achieve low-overhead beam training and high-precision perception. Background Art

[0002] With the rapid development of the sixth generation of mobile communications (6G) and the intelligent Internet of Things (IoT), integrated radar communication (ISAC) technology has become a key direction for achieving efficient spectrum utilization and hardware resource reuse.

[0003] Traditionally, communication and radar sensing functions have been implemented as separate systems: the communication module relies on cellular network protocols to transmit data, while the radar module transmits detection waves (such as millimeter waves and FMCW signals) to achieve target positioning. This discrete architecture leads to spectrum resource competition, redundant hardware deployment, and increased power consumption. For example, autonomous vehicles require both communication antennas and radar sensors, which not only takes up space but also reduces system reliability due to signal interference.

[0004] At the perception technology level, existing near-field beam training schemes use excessively large near-field codebooks, resulting in significant pilot overhead. Traditional radar systems, which cover the target area through point-by-point scanning, rely on large near-field codebooks to store beam configuration parameters for different ranges and angles, severely limiting the real-time responsiveness of perception.

[0005] Therefore, there is an urgent need for a technical solution for deep collaboration of communication perception. Summary of the Invention

[0006] In view of this, the present invention provides a radar perception method and system based on near-field beam splitting, which not only realizes functional multiplexing at the hardware layer, but also effectively reduces pilot overhead at the signal layer through innovative waveform and beam control.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] First, the present invention discloses a radar perception method based on near-field beam splitting. A broadband FMCW signal is transmitted through a MIMO array antenna, and near-field beam splitting is stimulated to obtain multiple sub-beams with the same distance but different angles. Radar perception is achieved based on each sub-beam. The perception steps include:

[0009] Determine target distance based on radar transmission signal and echo signal;

[0010] Determine the preliminary target angle based on the phase difference of the signals received by multiple antennas;

[0011] A near-field codebook is constructed based on the initial target angle and measurement error, and the beam splitting caused by frequency offset is compensated by adjusting the delay parameter.

[0012] The beam focusing vector is generated by controlling the phase shift circuit, transmitting the pilot signal and receiving feedback;

[0013] According to the feedback signal, the optimal angle is determined by energy maximization search.

[0014] In an optional embodiment, determining the target distance based on the radar transmission signal and the echo signal includes:

[0015] Mix the echo signal with the current transmit signal to generate an intermediate frequency signal;

[0016] Perform fast Fourier transform on the intermediate frequency signal to obtain the frequency corresponding to the spectrum peak;

[0017] The target distance is determined based on the frequency corresponding to the spectrum peak.

[0018] In an optional embodiment, the target distance is determined according to the following formula:

[0019]

[0020] Where, represents the speed of light, represents the slope, , Indicates bandwidth, Indicates the chirp duration, Indicates the peak of the spectrum.

[0021] In an optional embodiment, the calculation formula of the preliminary target angle is:

[0022]

[0023] Where, represents the target angle, represents the beam wavelength, Represents the distance between adjacent receiving antennas, Indicates the phase difference between antennas.

[0024] In an optional embodiment, the delay parameter satisfies the following formula:

[0025]

[0026] Where, is a predefined spatial angle that satisfies , 、 represent the minimum and maximum values of the predefined spatial angles, respectively, and , , represents the initial target angle, represents the measurement error, Indicates the lowest frequency, , Indicates the highest frequency, , represents the center carrier frequency, and B represents the bandwidth.

[0027] In an optional embodiment, the beam focusing vector is expressed as:

[0028]

[0029] Where, Represents the beam focusing vector The value of the nth element of Indicates the number of antennas, represents the wave number, , d represents the antenna indirect, , represents the central wavelength, , c represents the speed of light, represents the center carrier frequency, represents the delay parameter, represents the distance ring, , represents the initial target angle, represents the target distance, n represents the index of the BS antenna unit, , j represents the imaginary unit, which is used for complex domain phase modeling.

[0030] In an optional embodiment, the feedback signal is expressed as:

[0031]

[0032] Where, Indicates the transmit power, Expressed as frequency The near-field channel vector under represents the pilot signal transmitted to the target location, represents Gaussian noise, represents the beam focusing vector.

[0033] In an optional embodiment, determining the optimal angle through energy maximization search according to the feedback signal includes:

[0034]

[0035] Where, represents the optimal angle, represents the delay parameter, represents a predefined spatial angle, represents the center carrier frequency, is the predicted frequency index The corresponding frequency value, .

[0036] Second, the present invention discloses a radar sensing device based on near-field beam splitting, which applies any of the above-mentioned radar sensing methods based on near-field beam splitting, including:

[0037] Target distance determination module, target angle preliminary determination module and target angle correction module.

[0038] Third, the present invention discloses a radar perception system based on near-field beam splitting, the system comprising:

[0039] An integrated hardware platform, a common aperture antenna array, a composite RF front end and a collaborative signal processing unit, wherein the collaborative signal processing unit applies any of the above-described radar perception methods based on near-field beam splitting when performing target parameter estimation.

[0040] Fourth, the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed, it implements the radar perception method based on near-field beam splitting as described above.

[0041] The present invention discloses a radar sensing method and system based on near-field beam splitting. Compared with the existing technology, the present invention uses the near-field beam splitting effect to reduce the number of detection beams and lower the cost. At the same time, the use of radar sensing followed by beam training can effectively reduce pilot overhead and increase the communication rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0043] Figure 1 Flowchart of the radar perception method based on near-field beam splitting provided by the present invention. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0046] The present invention discloses a radar perception method and system based on near-field beam splitting, which can be applied to radar-based integrated synaesthesia systems. The core of synaesthesia integration lies in the coordinated optimization of communication and perception functions by sharing spectrum, hardware, and signal processing resources. The implementation principles include:

[0047] Waveform design: Designing joint signals that can transmit data and be used for sensing, such as those based on orthogonal frequency division multiplexing (OFDM). Its advantages in spectrum efficiency and anti-interference capabilities enable it to meet both communication and sensing needs.

[0048] Spectrum reuse: Communication and sensing share the same frequency band, and waveform design enables efficient use of spectrum resources and improves spectrum efficiency.

[0049] Communication and Perception Signal Multiplexing: The frequency-modulated continuous wave (FMCW) signal's perception properties enable target range and velocity analysis through echo delay-Doppler analysis. Multiple sub-beams formed by beam splitting provide high-resolution angular information. For communication, different sub-beams independently carry user data streams (OFDM subcarrier grouping). Beam splitting enables multi-user spatial division multiplexing (SDMA), while echo signals are used to extract environmental information (such as obstacle location).

[0050] Specifically, deep multiplexing of communication and perception is achieved at the hardware layer through the following designs:

[0051] Unified hardware platform: Utilizes the radio frequency link of communication base stations (such as 5G / 6G base stations) or terminal devices (such as mobile phones) to simultaneously transmit / receive communication signals and perception signals, reducing hardware costs;

[0052] Antenna array: The same array transmits FMCW signals, communication and perception share the same aperture, and the beam splits into sub-beams to simultaneously serve users and detect targets;

[0053] RF front end: Shares local oscillator and mixer, communication signal and radar echo are multiplexed in the same link through time division / frequency division;

[0054] Signal processing unit: Shared FFT / IFFT modules, joint design of communication pilot and radar pilot (such as FMCW embedded reference signal);

[0055] Beam controller: Frequency-domain beam steering based on beam splitting, unified scheduling of communication beams and perception beams.

[0056] Furthermore, when performing radar perception, the present application uses a very large-scale MIMO antenna array to transmit broadband FMCW signals. By regulating the signal bandwidth and array parameters to stimulate the near-field beam splitting phenomenon, a single main beam is decomposed into multiple spatially separated sub-beams. Each beam is focused at the same distance but at different angles. The focusing range of multiple beams is dynamically adjusted at different times to achieve multi-angle domain coverage, thereby reducing costs and achieving high-precision perception.

[0057] Because the angular resolution of an antenna array is much higher than its spatial resolution in terms of distance, the training overhead is primarily determined by the angle search. Therefore, this embodiment leverages the near-field beam splitting effect in the angular dimension to focus beams of different frequencies at multiple angles at the radar's target user distance, covering the entire potential angular range. This allows the optimal angle to be searched using a frequency-splitting method, significantly reducing training overhead.

[0058] The following is described by specific examples:

[0059] Example 1:

[0060] Applying this example to the forward collision avoidance radar system of an autonomous vehicle can integrate perception and communication, namely, detecting the distance and horizontal azimuth of vehicles within a range of 200 meters ahead in real time, and exchanging safety information with the target vehicle via a millimeter wave link.

[0061] In this embodiment, the steps of implementing radar sensing are as follows: Figure 1 As shown, including:

[0062] S1. Determine the target distance based on the radar transmission signal and the echo signal;

[0063] S2. Determine the preliminary target angle based on the phase difference of the multi-antenna received signals;

[0064] S3: Construct a near-field codebook based on the initial target angle and measurement error, and compensate for beam splitting caused by frequency offset by adjusting the delay parameter;

[0065] S4. Generate a beam focusing vector through phase shift circuit control, transmit a pilot signal and receive feedback;

[0066] S5. According to the feedback signal, the optimal angle is determined by energy maximization search.

[0067] In one embodiment,

[0068] When determining the target distance in S1, the radar generates a signal whose frequency changes linearly with time (chirp signal) and receives its echo.

[0069] In this embodiment, the parameters of the chirp signal are set as: starting frequency ,bandwidth , chirp duration s, slope , the speed of relative movement, v=30m / s.

[0070] Since the target user is moving, the echo frequency deviates from the transmission frequency, which is called Doppler shift. , c represents the speed of light.

[0071] Therefore, when the echo signal reflected by the target is multiplied and mixed with the signal currently being transmitted by the radar, an intermediate frequency signal is generated. The intermediate frequency signal is expressed as:

[0072]

[0073] Where, ± is determined by the direction of relative motion. When the target approaches the radar, the echo frequency increases and the value is +; conversely, when the target moves away from the radar, the value is -.

[0074] Uplink chirp IF , downlink chirp intermediate frequency .

[0075] Then perform a fast Fourier transform (FFT) on the intermediate frequency signal to convert it from the time domain to the frequency domain, and the frequency corresponding to the peak of the spectrum obtained is ;

[0076] Further determine the target distance based on the frequency corresponding to the spectrum peak ,

[0077]

[0078] In one embodiment,

[0079] When obtaining the preliminary target angle in S2, it is assumed that the number of base station antennas is The distance between two adjacent receiving antennas is d. Since electromagnetic waves travel one wavelength in space, The distance is exactly one cycle of the electromagnetic wave, that is, the phase rotates by 2 Angle, get:

[0080]

[0081] is the phase difference between antennas, that is, the phase corresponding to the spectrum peak position obtained by performing FFT on the same distance unit signal of multiple receiving antennas.

[0082] Finally, the initial angle of the target is obtained:

[0083]

[0084] Due to the limitation of antenna aperture, the angle of target user There will be a measurement error:

[0085]

[0086] Therefore, beam training is required to obtain a more accurate target user angle.

[0087] In one embodiment, the beam training step includes:

[0088] S3. Calculate angle delay parameters ;

[0089] First, define the antenna array parameters. This application is equipped with a uniform linear array and uses orthogonal frequency division multiplexing with M subcarriers to serve a single omnidirectional antenna user. The number of base station antennas is , n represents the index of the n-th BS antenna unit, .

[0090] represents the center carrier frequency, Indicates the subcarrier frequency B,c, , d represent bandwidth, speed of light, central wavelength and antenna spacing respectively, where,

[0091]

[0092]

[0093]

[0094] represents the wave number, represents the distance ring, and

[0095]

[0096]

[0097] In this embodiment, the samples are firstly taken from ( , ) to construct the near-field codebook at multiple angles, in order to ensure the wideband frequency-related angle (The role of the integer p is to ensure becomes the actual spatial angle) can cover the entire potential angle range ,make ( is a predefined spatial angle that satisfies );

[0098] By adjusting the delay parameters , indirectly controlling the integer p, and thus adjusting the degree of beam splitting.

[0099] To ensure Able to cover the entire angle range ,therefore The maximum value , Minimum value of , further with Combined, we get:

[0100]

[0101] Minimum frequency , the highest frequency .

[0102] Used to compensate for the angle deviation caused by frequency offset to ensure that the beam is at the center frequency Focus on .

[0103] Further, S4, the beam focusing vector is calculated.

[0104] Assume that each antenna in the base station is connected to a phase shift circuit. By controlling the delay in each antenna branch, each phase shift circuit can tune the frequency-dependent phase shift on the broadband signal. The phase shift circuit can control the angular coverage of the beam, that is, controllable near-field beam splitting is possible. , the phase shift circuit can occupy the entire angle range. The beam focusing vector is expressed as:

[0105]

[0106] Where, Represents the beam focusing vector The value of the nth element of Indicates the number of antennas, represents the wave number, , d represents the antenna indirect, , represents the central wavelength, , c represents the speed of light, represents the center carrier frequency, represents the delay parameter, represents the distance ring, , represents the initial target angle, represents the target distance, n represents the index of the BS antenna unit, , j represents the imaginary unit, which is used for complex domain phase modeling.

[0107] Then, the beam focusing vector is generated based on the base station , transmits a pilot signal to the target user location The frequency is The receiving signal Expressed as:

[0108]

[0109] The received signal reflects the current beam configuration The receiving strength of the signal at the user's location. Indicates the transmit power, represents Gaussian noise, Expressed as frequency The near-field channel vector under .

[0110] S5. Obtain an estimated spatial angle.

[0111] Finally, through the user's acceptance signal , calculate its energy.

[0112] When the beam parameters When the beam is close to the user's actual spatial angle, the main lobe of the beam is aligned with the user, and the signal energy is at its maximum. Therefore, the frequency value obtained based on the energy maximization search is:

[0113]

[0114] is the predicted frequency index, is the frequency value corresponding to the index.

[0115] The angle with the greatest energy corresponds to the spatial angle predicted by the user.

[0116]

[0117] Where, represents the optimal angle, represents the delay parameter, represents a predefined spatial angle, represents the center carrier frequency, is the predicted frequency index The corresponding frequency value, .

[0118] Example 2:

[0119] To facilitate the conversion of the perception method of the present application, the present application further provides a radar perception system based on near-field beam splitting, which applies any of the above-described radar perception methods based on near-field beam splitting, including:

[0120] A target distance determination module is used to determine the target distance based on the radar transmission signal and the echo signal;

[0121] A target angle preliminary determination module is used to determine the preliminary target angle based on the phase difference of the multi-antenna received signals;

[0122] The target angle correction module is used to construct a near-field codebook based on the initial target angle and measurement error, compensate for beam splitting caused by frequency offset by adjusting the delay parameter; generate a beam focusing vector through phase shift circuit control, transmit a pilot signal and receive feedback; and determine the optimal angle through energy maximization search based on the feedback signal.

[0123] In order to further optimize the above technical solution, a computer-readable storage medium can also be provided, in which a computer program is stored, so that when the computer program is executed, the radar perception method based on near-field beam splitting as described above is implemented.

[0124] The near-field beam splitting effect adopted by the present invention can reduce the number of detection beams, thereby reducing costs. At the same time, the use of radar perception followed by beam training can significantly reduce pilot overhead and increase communication speed.

[0125] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0126] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A radar sensing method based on near-field beam splitting, characterized in that the steps include: Determine target distance based on radar transmission signal and echo signal; Determine the preliminary target angle based on the phase difference of the signals received by multiple antennas; A near-field codebook is constructed based on the initial target angle and measurement error, and the beam splitting caused by frequency offset is compensated by adjusting the delay parameter. Control and generate beam focusing vectors, transmit pilot signals and receive feedback; According to the feedback signal, the optimal angle is determined by energy maximization search.

2. The radar sensing method according to claim 1, characterized in that: Determine the target distance based on the radar transmission signal and the echo signal, including: Mix the echo signal with the current transmit signal to generate an intermediate frequency signal; Perform fast Fourier transform on the intermediate frequency signal to obtain the frequency corresponding to the spectrum peak; The target distance is determined based on the frequency corresponding to the spectrum peak.

3. The radar sensing method according to claim 1, wherein: The target distance is determined according to the following formula: ； Where, represents the speed of light, represents the slope, , Indicates bandwidth, Indicates the chirp duration, Indicates the peak of the spectrum.

4. The radar sensing method according to claim 1, wherein: The calculation formula for the preliminary target angle is: ； Where, represents the target angle, represents the beam wavelength, Represents the distance between adjacent receiving antennas, Indicates the phase difference between antennas.

5. The radar sensing method according to claim 1, wherein: The delay parameter satisfies the following formula: ； Where, is a predefined spatial angle that satisfies , 、 represent the minimum and maximum values of the predefined spatial angles, respectively, and , , represents the initial target angle, represents the measurement error, Indicates the lowest frequency, , Indicates the highest frequency, , represents the center carrier frequency, and B represents the bandwidth.

6. The radar sensing method according to claim 1, characterized in that: The beam focusing vector is expressed as: ； Where, Represents the beam focusing vector The value of the nth element of Indicates the number of antennas, represents the wave number, , d means antenna indirect, , represents the central wavelength, , c represents the speed of light, represents the center carrier frequency, represents the delay parameter, represents the distance ring, , represents the initial target angle, represents the target distance, n represents the index of the BS antenna unit, , j represents the imaginary unit.

7. The radar sensing method according to claim 1, wherein: The feedback signal is expressed as: ； Where, Indicates the transmit power, Expressed as frequency The near-field channel vector under represents the pilot signal transmitted to the target location, represents Gaussian noise, represents the beam focusing vector.

8. The radar sensing method according to claim 1, characterized in that: According to the feedback signal, the optimal angle is determined by energy maximization search, including: ； Where, represents the optimal angle, represents the delay parameter, represents a predefined spatial angle, represents the center carrier frequency, is the predicted frequency index The corresponding frequency value, .

9. A radar sensing device based on near-field beam splitting, characterized in that: The radar sensing method based on near-field beam splitting according to any one of claims 1 to 8 is applied, comprising: A target distance determination module is used to determine the target distance based on the radar transmission signal and the echo signal; A target angle preliminary determination module is used to determine the preliminary target angle based on the phase difference of the multi-antenna received signals; The target angle correction module is used to construct a near-field codebook based on the initial target angle and measurement error, compensate for beam splitting caused by frequency offset by adjusting the delay parameter; generate a beam focusing vector through phase shift circuit control, transmit a pilot signal and receive feedback; and determine the optimal angle through energy maximization search based on the feedback signal.

10. A radar perception system based on near-field beam splitting, characterized in that: include: An integrated hardware platform for synchronous transmission and reception of communication signals and radar sensing signals by reusing the radio frequency links of communication base stations or terminal devices; A common aperture antenna array is used to form independently steerable communication and sensing sub-beams; A composite RF front end for processing communication signals and radar return signals using time division multiplexing and / or frequency division multiplexing mechanisms; A collaborative signal processing unit integrates a shared FFT / IFFT operation module, and realizes signal demodulation and target parameter estimation through a jointly designed communication pilot and radar pilot structure; wherein the target parameter estimation process applies the radar perception method based on near-field beam splitting described in any one of claims 1-8.

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