A method for angle estimation in a communication and perception integrated system

Abstract

This invention relates to an angle estimation method in an integrated communication and sensing system, belonging to the fields of wireless communication and radar technology. The angle estimation method in an integrated communication and sensing system is characterized by the base station simultaneously transmitting data in the downlink time slot. M There are data streams, among which M ≥2, the M Each data stream uses a different beamforming vector; the base station is based on the... M Constructing beamforming vectors P There are 1 guiding matrix, where P ≥2; the above P Each of the guidance matrices and N r The post-processed data from each receiving antenna is used to perform an inner product operation, resulting in... P The angle corresponding to the largest modulus among the inner product results is selected as the estimated angle of the target. N r ≥1.

Description

Technical Field

[0001] This invention relates to an angle estimation method in an integrated communication and sensing system, belonging to the fields of wireless communication and radar technology. Background Technology

[0002] With its higher operating frequency bands, wider spectrum bandwidth, and massive MIMO antenna arrays, 5G mobile communication systems have not only achieved significant improvements in transmission rates and user capacity but also possess the ability to perceive the physical environment with high precision. Integrated Sensing and Communication (ISAC) is widely considered one of the core technologies in 5G-Advanced and future 6G networks. Its goal is to achieve efficient data transmission and high-precision environmental perception functions in a coordinated manner within the same hardware infrastructure and signal framework.

[0003] Specifically, communication base stations transmit user data by transmitting radio waves carrying information, while simultaneously receiving echo signals reflected or scattered by objects in the environment. By processing these echo signals, the system can extract multi-dimensional parameters such as the target's distance, angle, and velocity relative to the base station, thereby achieving perception tasks such as high-precision positioning, dynamic trajectory tracking, and even classification and recognition of specific targets. Its basic architecture is as follows: Figure 1 As shown, the base station transmits electromagnetic waves modulated with information to the communication user to realize communication capability, and at the same time receives electromagnetic waves reflected by the target to obtain information such as the target's distance, speed, and angle, thus realizing the sensing function.

[0004] exist Figure 1 In the system architecture shown, the base station is equipped with a large-scale multi-array antenna for shared sensing (marked in red in the figure) and a dedicated antenna for sensing reception (marked in black in the figure). During downlink transmission time slots, the base station transmits beamformed communication signals to communication terminals (such as terminal 1 and terminal 2) through the shared sensing antenna; simultaneously, the dedicated sensing antenna is responsible for receiving echo signals reflected by moving targets in the environment. These echoes contain spatial and motion information of the targets, and key sensing parameters such as the target's distance, velocity, and angle can be extracted using appropriate signal processing algorithms.

[0005] This application addresses the problem of target angle estimation based on communication signals. It proposes a method to jointly estimate the target angle of arrival (AoA) using the communication signals transmitted from the base station to the communication terminal and their corresponding beamforming vectors. This method fully leverages the sensing potential of the communication signals without affecting normal communication, thereby improving the accuracy of angle estimation and the system's spectral efficiency.

[0006] Traditional methods often require increasing the number of antennas to improve angle estimation accuracy. However, since dedicated sensing antennas are used only for sensing tasks and do not participate in communication transmission, increasing their number does not directly improve communication performance. On the contrary, it may reduce the overall system's hardware utilization efficiency due to insufficient reuse of antenna resources.

[0007] Therefore, this application aims to explore novel methods and system architectures that can still achieve high-precision angle estimation when the number of dedicated sensing antennas is small (e.g., only a few antennas are configured, or even only one dedicated sensing antenna), thereby improving the overall utilization efficiency of antenna resources while ensuring sensing performance. Summary of the Invention

[0008] To address the problems existing in the prior art, an angle estimation method is provided for an integrated communication and sensing system.

[0009] The present application aims to solve the above-mentioned technical problems through the following technical solution: An angle estimation method in a communication-sensing integrated system, characterized by the base station simultaneously transmitting data in the downlink time slot. M There are data streams, among which M≥2 The M Each data stream uses a different beamforming vector; the base station is based on the... M Constructing beamforming vectors P There are 1 guiding matrix, where P ≥2; the above P Each of the guidance matrices and N r The post-processed data from each receiving antenna is used to perform an inner product operation, resulting in... P The angle corresponding to the largest modulus among the inner product results is selected as the estimated angle of the target. N r ≥1.

[0010] Based on the above technical solution, this application further improves and refines the above technical solution as follows: Furthermore, the aforementioned P The method for constructing the guidance matrix is ​​as follows: Set the starting angle for angle search Search step size The termination angle is ; For each candidate angle , Construct a normalized guidance matrix: , , in: , , , In the formula: The direction angle of the incoming wave is The corresponding steering vector for the sensing-specific antenna, where the direction angle of arrival is the angle between the direction of arrival and the normal of the sensing-specific antenna array. For the direction of wave removal is The corresponding common antenna steering vector, where the deflection direction angle is the angle between the deflection direction and the normal of the common antenna array. When the dedicated sensing antenna array and the shared sensing antenna array are coplanar and parallel, and the sensed target is in the far field, the incoming wave direction angle and the outgoing wave direction angle are the same. j It is an imaginary number. , T represents transpose. and These represent the number of dedicated sensing antennas and the number of shared sensing antennas, respectively. and These are the spacing between dedicated sensing antennas and the spacing between shared sensing antennas, respectively. The wavelength of the carrier frequency, , , Vector, is the first Beamforming weights for each user For the normalized guiding matrix, Representation matrix The Frobenius norm.

[0011] Furthermore, the aforementioned Post-processing on each receiving antenna includes matched filtering and inter-symbol interference cancellation steps for separation. Each communication data stream is isolated and its mutual interference is suppressed.

[0012] Furthermore, the aforementioned Each guiding matrix and The specific method for performing inner product operations on the post-processed data from each receiving antenna is as follows: For each normalized steering matrix: , ,calculate: , in: Post-processing data on each receiving antenna For the angle is The corresponding normalized steering matrix of the first Line number Column elements, For the angle is The result of the corresponding inner product operation. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of integrated communication and sensing. Figure 2 Equipped with base station A dedicated sensing antenna. Detailed Implementation

[0014] The following embodiments, in conjunction with the accompanying drawings, are merely for illustrating the technical solutions described in the claims and are not intended to limit the scope of protection of the claims.

[0015] In Integrated Sensing and Communication (ISAC) systems, dedicated sensing antennas are typically designed as arrays to achieve accurate estimation of target angles. Assume this dedicated sensing antenna array consists of... It consists of several antenna elements arranged in a linear, equally spaced manner, with the spacing between adjacent antennas being [missing information]. For a spatial angle of The goal, in the At that moment, it was The phase relationship of the echo signals received on each antenna element can be expressed in the following vector form: On the base station side, a steering vector is typically defined to describe the phase effect of different incoming wave direction angle signals on the antenna array: Based on the received signal Target angle estimation can be achieved through... This is achieved by searching for spectral peaks within the range of values, i.e., finding peaks that make... To obtain the maximum value ,Should This is the estimated value of the target angle: The accuracy of target angle estimation is related to the aperture of the sensing-dedicated antenna array (i.e., This is closely related to the angle resolution. Generally speaking, the larger the aperture, the stronger the angle resolution and the higher the estimation accuracy. Therefore, traditional methods often require increasing the number of antennas to improve angle estimation accuracy. However, since dedicated sensing antennas are used only for sensing tasks and do not participate in communication transmission, increasing their number does not directly improve communication performance. On the contrary, it may reduce the overall system's hardware utilization efficiency due to insufficient reuse of antenna resources.

[0016] Therefore, this application aims to explore novel methods and system architectures that can still achieve high-precision angle estimation when the number of dedicated sensing antennas is small (e.g., only a few antennas are configured, or even only one dedicated sensing antenna), thereby improving the overall utilization efficiency of antenna resources while ensuring sensing performance.

[0017] This application proposes an efficient angle estimation method for the target angle estimation problem in the communication-sensing integrated (ISAC) system, where the base station is equipped with a shared sensing antenna array and a small number (or even only one) of dedicated sensing antennas.

[0018] Assuming the base station is equipped with A shared antenna for multiple induction, simultaneously providing signal transmission in a certain downlink time slot. Data is transmitted to the first communication user. Assume the base station transmits data to the first... The length sent by each user is data sequence , is represented as: Base stations use beamforming weight vectors Where T is the transpose operation. express A set of complex vectors with 1 row and 1 column; Will Mapped to The transmitted signal matrix is ​​used to realize the transmission signal matrix. The transmission is shared by multiple inductive antennas. The beamforming process is specifically described as follows: In the formula: For transmission to the first The communication user, in the _th ... The first transmitting antenna Data for each sample point; The beamforming weights on the k-th transmit antenna for transmitting data to the m-th communication user; For the transmission to the m-th communication user, the first... Data for each sample point; During this time slot, the base station provides simultaneous services. There are [number] users, therefore the total transmitted data matrix at the base station is [number]. This can be represented as the superposition of beamformed signals from each user: Furthermore, assuming the base station is equipped with A dedicated sensing antenna to meet the requirements and For spaces located at angles The target, whose echo signal traverses the channel path as follows: from The signal is transmitted via a shared antenna and, after being reflected by the target, is... A dedicated sensing antenna receives the signal. This sensing channel can be modeled as follows: (6) in, This is a complex value, including path loss, target reflection coefficient, and initial phase response; assuming the shared transmitting antenna and the dedicated receiving antenna are coplanar and parallel, when the target is in the far field, it has the same angle with both the transmitting and receiving antennas. .at this time, These are the steering vectors for the receiving and transmitting antenna arrays, respectively, and their specific expressions are as follows: (7) (8) here, and These are the spacing between the receiving antennas and the transmitting antennas, respectively. It is the quantity to be estimated, at the p-th attempt, Pick .

[0019] Based on the above channel and signal model The signal matrix received by a dedicated sensing antenna It can be represented as: in, For receiving antenna in Additive noise introduced within one symbol period.

[0020] Below, we will elaborate on the proposed angle estimation method step by step: Step 1: Matched filtering: Filtering the received signal matrix Each line, respectively with Perform an inner product operation on each transmitted communication data, that is... To more clearly express the subsequent processing flow, we represent equation (10) in matrix form: make , can be obtained Step 2: Remove inter-symbol interference: To eliminate Interference between user signals affects the matched filter output. Perform related processing: This step effectively restores the signal structure after beamforming and sensing channel processing.

[0021] Step 3: Construct a set of normalized guidance matrices: Set the angle search range to ,in Starting angle, This is the search step size. For each candidate angle... Construct the corresponding guidance matrix: Then, normalization was performed: in This represents the Frobenius norm of the matrix. The normalization operation ensures fair comparisons of subsequent related metrics.

[0022] Step 4: Angle Search and Estimation For each normalized steering matrix Calculate its relationship with the signal after interference cancellation. Correlation coefficient: In all the correlation coefficients obtained Find the modulus value in the middle. Largest index Then the estimated value of the target angle is: This method makes full use of the beamforming gain of the shared sensing antenna and the receiving capability of the dedicated sensing antenna, achieving high-precision angle estimation while ensuring communication performance.

[0023] The technical solution of this application has the following advantages: (i) The requirement for the number of dedicated sensing antennas is low.

[0024] The method in this application offers high flexibility in the number of dedicated sensing antennas that can be configured. It can simultaneously serve at least two downlink users (i.e.,...) M ≥2 It can still effectively estimate the target angle, breaking through the limitation of the number of receiving antennas in traditional methods.

[0025] For scenarios where only a single communication user is scheduled for downlink, the system can proactively introduce an auxiliary data stream. This data stream uses different beamforming weights than the communication user's and does not carry actual user data. It is specifically used to enhance the signal dimension required for angle estimation, thereby ensuring reliable angle estimation capability even with a minimized dedicated sensing antenna configuration.

[0026] (ii) The scale benefits of shared antennas are significant.

[0027] Increase the number of shared antennas for inductive communication It can simultaneously improve communication and sensing performance. On the one hand, the larger antenna size brings higher beamforming gain, directly improving the received signal-to-noise ratio for communication users; on the other hand, the transmit antenna steering vector... Different beamforming vectors With enhanced spatial discrimination capabilities, it helps to more accurately resolve target angle information at the receiving end, thereby effectively improving the accuracy of angle estimation. This hardware resource reuse mechanism achieves a synergistic improvement in communication and sensing performance.

[0028] (iii) Low implementation complexity.

[0029] This application has a significant advantage in computational efficiency. Its core component—constructing the orientation matrix—is key. — It can pre-calculate and store the search range based on preset angles, eliminating the need for repeated calculations during actual operation and significantly saving online computing resources.

[0030] The main computational load of the algorithm is concentrated in the angle search step, and the complexity of this step depends on the dimension of the guidance matrix. Due to the number of dedicated sensing antennas in actual systems and downlink scheduling user number They are usually kept to a small scale, so the overall search process has limited computational cost and can be easily implemented in real time on existing hardware platforms.

[0031] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An angle estimation method in a communication-sensing integrated system, characterized in that, Base stations transmit simultaneously in downlink time slots M There are data streams, among which M ≥2, the M Each data stream uses a different beamforming vector; the base station is based on the... M Constructing beamforming vectors P There are 1 guiding matrix, where P ≥2; the above P Each of the guidance matrices and N r The post-processed data from each receiving antenna is used to perform an inner product operation, resulting in... P The angle corresponding to the largest modulus among the inner product results is selected as the estimated angle of the target. N r ≥1.

2. The angle estimation method in the integrated communication and sensing system according to claim 1, characterized in that, The P The method for constructing the guidance matrix is ​​as follows: Set the starting angle for angle search Search step size Termination angle for ; For each candidate angle , Construct a normalized guidance matrix: ， ， in: ， ， ， In the formula: The direction angle of the incoming wave is The corresponding steering vector for the sensing-specific antenna, where the direction angle of arrival is the angle between the direction of arrival and the normal of the sensing-specific antenna array. For the direction of wave removal is The corresponding common antenna steering vector, where the deflection direction angle is the angle between the deflection direction and the normal of the common antenna array. When the dedicated sensing antenna array and the shared sensing antenna array are coplanar and parallel, and the sensed target is in the far field, the incoming wave direction angle and the outgoing wave direction angle are the same. j It is an imaginary number. T represents transpose. and These represent the number of dedicated sensing antennas and the number of shared sensing antennas, respectively. and These are the spacing between dedicated sensing antennas and the spacing between shared sensing antennas, respectively. The wavelength of the carrier frequency; , ,for Vector, is the first Beamforming weights for each user; The normalized guiding matrix; Representation matrix The Frobenius norm.

3. The angle estimation method in the integrated communication and sensing system according to claim 1 or 2, characterized in that, The Post-processing on each receiving antenna includes matched filtering and inter-symbol interference cancellation steps for separation. Each communication data stream is isolated and its mutual interference is suppressed.

4. The angle estimation method in the integrated communication and sensing system according to claim 1, characterized in that, The Each guiding matrix and The specific method for performing inner product operations on the post-processed data from each receiving antenna is as follows: For each normalized steering matrix: , ,calculate in: Post-processing data on each receiving antenna For the angle is The corresponding normalized steering matrix of the first Line number Column elements, For the angle is The result of the corresponding inner product operation.

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