Target positioning method and device, storage medium and program product

Abstract

The invention discloses a target positioning method and device, a storage medium and a program product, relates to the technical field of communication perception integration, and discloses a target positioning method, the target positioning method is applied to a communication base station, and comprises the following steps: sending a perception signal to at least one target object; receiving an echo signal of the sensing signal reflected by the at least one target object; obtaining prior information of the at least one target object, and processing the echo signal based on the prior information to obtain an angle measurement value and a distance measurement value of the at least one target object; and determining positioning information of the at least one target object according to the angle measurement value and the distance measurement value. According to the technical scheme, it can be guaranteed that multiple targets are accurately positioned, meanwhile, the calculation complexity of a positioning information measurement scheme is reduced, and better balance between positioning performance and complexity is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of integrated communication and perception, and in particular to a target positioning method, device, storage medium, and program product. Background Art

[0002] The integration of communication and perception functions in mobile communication systems is a key research direction in the current industry. Existing perception solutions for localizing passive objects within this integrated communication and perception framework fall into two main categories: joint measurement of object angle and distance, and independent measurement.

[0003] However, when joint measurement schemes are used to locate multiple targets, the echo signals from these multiple targets overlap, resulting in intertwined phase difference information and an inability to distinguish the angular distance parameters of different targets. This makes it only suitable for single-target positioning scenarios. While independent measurement schemes support multi-target positioning, they still suffer from high computational complexity. The common MUSIC algorithm requires a full traversal of the spectrum peaks. While combining iterative optimization algorithms (such as the dung beetle algorithm) reduces complexity, it suffers from significant parameter sensitivity and a performance-complexity imbalance when the positioning scenario changes.

[0004] Therefore, the existing technology lacks a solution that takes into account both the accuracy and complexity of multi-target positioning.

[0005] The above content is only used to assist in understanding the technical solution of this application and does not constitute an admission that the above content is prior art. Summary of the Invention

[0006] The main purpose of this application is to provide a target positioning method, device, storage medium and program product, aiming to solve the technical problem that the existing technology lacks a solution that takes into account the accuracy and complexity of multi-target positioning.

[0007] To achieve the above objectives, the present application proposes a target positioning method, which is applied to a communication base station and includes:

[0008] sending a sensing signal to at least one target object;

[0009] receiving an echo signal of the sensing signal reflected by the at least one target object;

[0010] Acquiring prior information of the at least one target object, and processing the echo signal based on the prior information to obtain an angle measurement value and a distance measurement value of the at least one target object;

[0011] The positioning information of the at least one target object is determined according to the angle measurement value and the distance measurement value.

[0012] In one embodiment, the step of obtaining the prior information of the at least one target object includes:

[0013] Acquiring adjacent perception information of the at least one target object;

[0014] Determine the prior information of the at least one target object based on the adjacent sensing information, where the prior information includes at least position and speed information of the target object.

[0015] In one embodiment, the step of processing the echo signal based on the prior information to obtain the angle measurement value and the distance measurement value of the at least one target object includes:

[0016] Based on the prior information, construct at least one spatial domain of the target object, wherein the spatial domain includes at least one of a two-dimensional angle domain and a position domain;

[0017] determining a received signal matrix according to the echo signal;

[0018] Processing the received signal matrix using a multiple signal classification algorithm according to the spatial domain union of the at least one target object to obtain an angle measurement value of the at least one target object;

[0019] Performing beamforming on an echo direction corresponding to an angle measurement value of at least one target object in the echo signal to obtain at least one single-path echo signal;

[0020] constructing an observation matrix of the at least one target object according to the single-path echo signal and the sensing signal;

[0021] The measurement matrix is processed using a multiple signal classification algorithm according to the spatial domain of the target object to obtain a distance measurement value of the at least one target object.

[0022] In one embodiment, the step of constructing at least one spatial domain of the target object based on the prior information includes:

[0023] Determining maximum acceleration information of the target object based on the position and velocity information of the target object;

[0024] Determining a spherical area of the target object in a preset spherical coordinate system according to the target object position information, velocity information, and maximum acceleration information;

[0025] The position domain of the target object is determined according to the center position and the radius of the spherical area.

[0026] In one embodiment, the step of constructing at least one spatial domain of the target object based on the prior information further includes:

[0027] Determine a conical angle domain in a preset spherical coordinate system according to the spherical area;

[0028] The two-dimensional angle domain of the target object is determined according to the semi-apex angle of the conical angle domain and the two-dimensional angle of the center of the spherical area.

[0029] In one embodiment, the step of processing the received signal matrix using a multiple signal classification algorithm based on the spatial domain union of the at least one target object to obtain the angle measurement value of the at least one target object includes:

[0030] Using the union of the two-dimensional angle domains of the at least one target object as the first spatial spectrum range of the multiple signal classification algorithm;

[0031] Processing the received signal matrix using the multiple signal classification algorithm to construct an angle spectrum function;

[0032] According to the first spatial spectrum range, a spectrum peak search is performed on the angle spectrum function to determine an angle measurement value of the at least one target object.

[0033] In one embodiment, the step of processing the measurement matrix using a multiple signal classification algorithm based on the spatial domain of the target object to obtain the distance measurement value of the at least one target object includes:

[0034] For each target object, determining a second spatial spectrum range of the multiple signal classification algorithm according to a location domain of the target object;

[0035] Processing the measurement matrix using the multiple signal classification algorithm to construct a delay spectrum function;

[0036] performing a spectrum peak search on the delay spectrum function according to the second spatial spectrum range to obtain a propagation time of an echo signal corresponding to the target object;

[0037] A distance measurement value of the target object is determined based on the propagation time and the speed of light.

[0038] In addition, to achieve the above-mentioned purpose, the present application also proposes a target positioning device, which includes: a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the target positioning method as described above.

[0039] In addition, to achieve the above-mentioned purpose, the present application also proposes a storage medium, which is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by the processor, the steps of the target positioning method described above are implemented.

[0040] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the steps of the target positioning method described above.

[0041] One or more technical solutions proposed in this application have at least the following technical effects:

[0042] The target positioning method, device, storage medium, and program product proposed in the embodiments of the present application specifically send a perception signal to at least one target object; receive an echo signal reflected by the perception signal from the at least one target object; obtain prior information of the at least one target object, and process the echo signal based on the prior information to obtain an angle measurement value and a distance measurement value of the at least one target object; and determine the positioning information of the at least one target object based on the angle measurement value and the distance measurement value.

[0043] This application utilizes a communication base station to send a communication signal for sensing to one or more target objects, and receives one or more echo signals reflected by the target objects; by obtaining prior information of the target objects, the echo signals are processed to obtain angle measurement values and distance measurement values of the one or more target objects, and by combining the position information of the communication base station, the one or more target objects can be accurately positioned. At the same time, the use of prior information can effectively reduce the computational complexity in the angle and distance measurement process, thereby ensuring that multiple targets can be accurately positioned while reducing the computational complexity of the positioning information measurement scheme, thereby achieving a better balance between positioning performance and complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0045] In order to more clearly illustrate the embodiments of the present application 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, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0046] Figure 1 A flowchart of the first embodiment of the target positioning method of the present application is provided;

[0047] Figure 2 A flowchart of the second embodiment of the target positioning method of this application is provided;

[0048] Figure 3A flowchart of the target positioning method according to the third embodiment of the present invention is provided;

[0049] Figure 4 Schematic diagram of the device structure of the hardware operating environment involved in the target positioning method in the embodiment of the present application;

[0050] Figure 5 This is a geometric model of an object positioning scene involved in Example 2 of this application.

[0051] The purpose, features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0052] It should be understood that the specific embodiments described herein are merely used to explain the technical solutions of the present application and are not intended to limit the present application.

[0053] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0054] The main solution of the embodiment of the present application is: sending a perception signal to at least one target object; receiving an echo signal reflected by the perception signal from the at least one target object; obtaining prior information of the at least one target object, and processing the echo signal based on the prior information to obtain an angle measurement value and a distance measurement value of the at least one target object; and determining the positioning information of the at least one target object based on the angle measurement value and the distance measurement value.

[0055] Technical terms involved in this application:

[0056] Integrated Sensing and Communication (ISAC): ISAC is a key technology in the 5G / 6G field. It aims to enable communication systems to simultaneously support high-speed data transmission and environmental perception (such as target detection, positioning, and speed measurement) through hardware and software collaborative design. Its core lies in sharing spectrum, hardware, and channel resources, breaking the functional boundaries between traditional communication and radar / perception systems. For example, in the Internet of Vehicles, base stations can simultaneously transmit data and sense vehicle location, improving resource utilization. Advantages include reduced equipment costs, enhanced system reliability, and providing a technical foundation for future intelligent transportation and smart cities.

[0057] Multiple Signal Classification (MUSIC): The MUSIC algorithm is a signal processing technology based on high-resolution spectral estimation, which is used to separate and identify multiple signal sources in a complex environment. Its principle is to decompose the mixed signal into independent components by calculating the orthogonality of the signal subspace and the noise subspace. Typical applications include radar multi-target recognition, interference suppression in wireless communications, and medical imaging. The algorithm achieves accurate classification through feature extraction (such as time-frequency domain analysis) and machine learning models (such as deep learning), especially in low signal-to-noise ratio environments, significantly improving the system's adaptability to scenarios such as multipath effects and multi-user concurrency.

[0058] In this embodiment, for ease of description, the following description is made with the target positioning device as the execution subject.

[0059] Integrating the communication and perception functions of mobile communication systems is a key research direction in the current industry. Existing research reports on this area indicate that future application scenarios for this integration include smart factories, intelligent transportation, smart living, and drone monitoring.

[0060] Various perception services in communication and perception integration are mainly implemented based on state parameters such as object position, velocity, and acceleration. Therefore, the perception performance of object state parameters is the main factor affecting the quality of perception services.

[0061] The positioning of passive objects is an important component of the perception function in communication and perception integration. Existing perception solutions for the positioning of passive objects are mainly divided into two categories, including joint measurement solutions of object angle and distance and independent measurement solutions.

[0062] While joint angle and distance measurement schemes can measure both angle and distance simultaneously, they can only locate a single object. If multiple objects are present in a scene, their echo signals will overlap, making it impossible to distinguish the angle and distance between each object and the base station. Therefore, this type of solution is not suitable for locating multiple objects.

[0063] The independent measurement scheme can be used to simultaneously locate multiple objects in a scene, and its application range is wider. The independent measurement scheme usually first performs angle measurement on the received echo signal. Among them, existing angle measurement algorithms include conventional beamforming algorithms, MUSIC algorithms, etc. Then, based on the direction of each object relative to the base station obtained by the angle measurement, beamforming is performed separately for each direction. This is equivalent to retaining only the signal in the echo direction of each object and filtering out the received signals in other directions, thereby screening out the echo signals of each object. Then, the inverse Fourier transform algorithm, MUSIC algorithm, etc. can be used to measure the distance between a single object and the base station. Considering that the inverse Fourier transform algorithm has low resolution and is easily affected by interference factors, the MUSIC algorithm is more commonly used.

[0064] However, the spectrum construction and peak search process of the MUSIC algorithm require a large amount of computation. Even if the peak search process that traverses all sample points is modified to implement the peak search through an iterative optimization algorithm, such as the dung beetle algorithm, genetic algorithm, Newton descent algorithm and other iterative optimization algorithms, in order to reduce the computational complexity, the computational complexity of the iterative optimization algorithm is more dependent on the preset parameters. Inappropriate parameters will lead to performance impairment or insignificant reduction in computational complexity, and thus a performance-complexity imbalance is prone to occur when the positioning scene changes.

[0065] Therefore, the existing technology lacks a solution that takes into account both the accuracy and complexity of multi-target positioning.

[0066] The present application provides a solution, which utilizes a communication base station to send a communication signal for sensing to one or more target objects and receive one or more echo signals reflected by the target objects; by obtaining prior information of the target objects, the echo signals are processed to obtain angle measurement values and distance measurement values of the one or more target objects, and by combining the position information of the communication base station, the one or more target objects can be accurately positioned. At the same time, the use of prior information can effectively reduce the computational complexity of the angle and distance measurement process, thereby ensuring that multiple targets can be accurately positioned while reducing the computational complexity of the positioning information measurement scheme, thereby achieving a better balance between positioning performance and complexity.

[0067] It should be noted that the execution subject of this embodiment can be a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, mobile phone, etc., or an electronic device or target positioning device capable of implementing the above functions. The following uses the target positioning device as an example to illustrate this embodiment and the following embodiments.

[0068] Based on this, the embodiment of the present application provides a target positioning method, referring to Figure 1 , Figure 1This is a flowchart of the first embodiment of the target positioning method of the present application.

[0069] In this embodiment, the target positioning method is applied to a communication base station, and the target positioning method includes steps S10 to S40:

[0070] Step S10, sending a sensing signal to at least one target object;

[0071] Step S20, receiving an echo signal of the sensing signal reflected by the at least one target object;

[0072] Since the present application is applied to the integrated communication and perception scenario, the target positioning method is applied to the communication base station. The communication base station first sends a perception signal to one or more passive objects (i.e., target objects) to be perceived in the current perception scenario through steps S10 and S20, and receives the echo signal reflected by the target object from the perception signal, so as to subsequently obtain the positioning information of the target object, including state parameters such as position, direction, speed, and acceleration, by performing signal processing on the echo signal corresponding to the reflection of the target object.

[0073] In addition, in the integrated communication and perception scenario, the perception signal should be a signal used for communication, including communication signals such as FBMC (Filter Bank Multi-Carrier) waveform, OTFS (Orthogonal Time Frequency Space) waveform, and OFDM (Orthogonal Frequency-Division Multiplexing) waveform. Since the currently widely used 4G and 5G mobile communication systems all use OFDM waveforms, the design idea with the highest compatibility is to use a part of the resource elements (RE) in the OFDM signal for perception, thereby integrating the perception function into the communication system without changing the mobile communication equipment as much as possible, thereby reducing the cost of system upgrades. Therefore, in the embodiment of the present application, the perception signal or echo signal is preferably an ODFM signal.

[0074] It should be understood that when the location information of the target object is unclear, when there are multiple target objects in the perception scene, the target positioning device can send perception signals to multiple target objects by emitting uniform OFDM signal radiation into space, and at the same time receive multiple echo signals reflected by each target object in the perception scene.

[0075] Step S30, obtaining prior information of the at least one target object, and processing the echo signal based on the prior information to obtain an angle measurement value and a distance measurement value of the at least one target object;

[0076] It should be noted that prior information includes, but is not limited to, prior knowledge such as target object motion state prediction data and environmental map data. Angle measurements refer to the azimuth and / or elevation angles of the target object relative to the perception system (i.e., the communication base station), while distance measurements represent the straight-line distance between the target object and the perception system.

[0077] Specifically, the target positioning device needs to obtain prior information about a target object before processing the echo signal reflected by the target object. If there are multiple targets, the prior information of multiple targets must be obtained in advance. Then, combining the prior information of all the targets, the echo signal is subjected to multi-level signal processing, including echo signal preprocessing, time-frequency domain analysis, direction of arrival calculation (i.e., target object angle calculation), and distance calculation, to achieve angle measurement and distance measurement of the target object.

[0078] A common way to combine prior information is usually to use the target object speed information in the prior information to correct the frequency offset of the echo signal during the preprocessing of the echo signal, thereby improving the distance measurement accuracy. In addition, after the preliminary angle measurement value and distance measurement value are obtained through the solution, the prior information can be used to further optimize them to improve the positioning accuracy of the object.

[0079] The core of calculating the direction of arrival is to infer the spatial angle of the signal source through the phase difference of the multi-channel received signals. This can be achieved by using subspace decomposition algorithms (such as the MUSIC algorithm and the rotation-invariant subspace algorithm), deep learning algorithms, compressed sensing and sparse reconstruction algorithms, conventional beamforming algorithms, etc.

[0080] The core of calculating the distance to the target object lies in calculating the time delay difference between the perception signal and the echo signal, which can be achieved by using the inverse Fourier transform algorithm, MUSIC algorithm, etc.

[0081] In a feasible implementation, the step of obtaining the prior information of the at least one target object may include steps A301 to A302:

[0082] Step A301, obtaining adjacent perception information of the at least one target object;

[0083] Step A302: Determine the prior information of the at least one target object based on the adjacent sensing information, where the prior information at least includes the position and speed information of the target object.

[0084] It should be noted that adjacent perception information refers to the temporally adjacent perception information of the target object in the previous perception information of the communication base station before this perception during the continuous perception of the target object, where the perception information includes the distance, speed, angle, position information, etc. of the target object.

[0085] In this embodiment, the target positioning device needs to obtain the perception information of all target objects in the current perception scene in the previous n perceptions before perceiving the target object, and then determine the position, speed, acceleration and motion trajectory of the target object based on the perception information to constitute the prior information of the target object. It should be understood that the number n is not specifically limited.

[0086] It should be understood that this embodiment does not limit the method of obtaining adjacent perception information of the target object. It can be obtained through the current communication base station, one or more other communication base stations through the angle-distance-Doppler three-dimensional joint super-resolution method, or by superimposing the object Doppler frequency shift analysis method (such as maximum likelihood estimation or extended Kalman filtering) on the common joint measurement scheme and the independent measurement scheme.

[0087] Step S40 : determining the location information of the at least one target object according to the angle measurement value and the distance measurement value.

[0088] Specifically, the target positioning device can obtain the three-dimensional coordinates of each target object in the current perception scene, that is, the positioning information of the target object, by combining the angle measurement value and the distance measurement value of each target object in the spatial coordinate system with the current communication base station as the origin.

[0089] This embodiment provides a target positioning method, which uses a communication base station to send a communication signal for sensing to one or more target objects and receive one or more echo signals reflected by the target objects; by obtaining prior information of the target objects, the echo signals are processed to obtain angle measurement values and distance measurement values of the one or more target objects, and by combining the position information of the communication base station, the one or more target objects can be accurately positioned. At the same time, the use of prior information can effectively reduce the computational complexity of the angle and distance measurement process, thereby ensuring that multiple targets can be accurately positioned while reducing the computational complexity of the positioning information measurement scheme, thereby achieving a better balance between positioning performance and complexity.

[0090] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as those in the above embodiment 1 can be referred to the above introduction and will not be described in detail later. Figure 2The step of processing the echo signal based on the prior information to obtain the angle measurement value and the distance measurement value of the at least one target object includes steps S31 to S36:

[0091] Step S31, constructing at least one spatial domain of the target object based on the prior information, wherein the spatial domain includes at least one of a two-dimensional angle domain and a position domain;

[0092] It should be noted that the spatial domain describes the possible distribution characteristics of the target object in physical space during the time interval t0 between the previous and current perceptions, including but not limited to the two-dimensional angle domain and the position domain. The two-dimensional angle domain refers to the range of possible azimuth and elevation angles of the target object during t0, while the position domain refers to the three-dimensional spatial range in which the target object may exist during t0.

[0093] Specifically, the target positioning device uses the aforementioned prior information to construct one or more spatial domains of the target object, namely, the target object's two-dimensional angle domain and / or position domain. By constructing the target object's spatial domain, the target object's possible motion state characteristics at the time of the current perception can be converted into quantifiable spatial parameters, thereby improving the robustness of angle and distance measurements.

[0094] In a feasible implementation, when the spatial domain is a location domain, step S31 may include steps A311 to A313:

[0095] Step A311, determining the maximum acceleration information of the target object based on the position and velocity information of the target object;

[0096] First, when constructing the position domain of the target object, we can choose to determine the maximum acceleration of the target object in the previous continuous perception process in a three-dimensional rectangular coordinate system with the current communication base station as the origin through the historical position and velocity information of the target object in the prior information. Then, we use a dynamic model, such as a uniform acceleration model or a maneuvering target model, to further adjust and obtain the maximum acceleration that the target object may generate in the current motion state by adding an acceleration noise value that can be freely set according to the actual scenario, or by setting the acceleration change frequency.

[0097] Step A312: determining a spherical area of the target object in a preset spherical coordinate system based on the target object position information, velocity information, and maximum acceleration information;

[0098] Step A313: Determine the location domain of the target object based on the center position and the radius of the spherical area.

[0099] It should be noted that the preset spherical coordinate system is a three-dimensional coordinate system with the current communication base station as the sphere center.

[0100] Reference Figure 5 The geometric model of an object positioning scenario (i.e., a perception scenario) is shown. In a three-dimensional rectangular coordinate system with the center of the antenna array plane in the geometric model as the origin, the target positioning device first uses the position information, velocity information, and maximum acceleration information of each target object in the prior information to determine the possible distribution area of the target object in the three-dimensional rectangular coordinate system during the current perception. Since the origin of the above three-dimensional rectangular coordinate system is consistent with the origin of the preset spherical coordinate system, the possible distribution area in the above three-dimensional rectangular coordinate system is converted into spherical coordinates for representation, that is, the spherical area of the target object in the preset spherical coordinate system. Based on the center position of the spherical area and the radius of the sphere, the distance range between the target object and the current communication base station, i.e., the location domain of the target object, is determined.

[0101] It should be noted that the target sensing method in the embodiment of the present application mainly considers the sensing scenario of a single communication base station. Below, the communication base station is described as a static communication base station.

[0102] Reference Figure 5 In the three-dimensional rectangular coordinate system of the geometric model, the antenna array plane (representing the communication base station) is located in the YOZ plane, the array center is located at the origin O of the coordinate system, there are N objects in the scene, and the distance between the objects and the antenna array is much larger than the spacing between the antennas. Therefore, when the base station transmits a signal to the object and receives an echo signal, the echo signal can be regarded as a far-field signal, that is, the direction of the echo signal received by each antenna is approximately the same.

[0103] Among them, the pitch angle of the echo signal of the nth object is θ n , the azimuth is θ n ∈[-90°,90°], The position coordinates of the object are (x n ,y n ,z n ), the movement speed is v n , n∈{1,2,...,N}.

[0104] In this object positioning scenario, the perception of objects is a continuous process. Let the time interval between the previous perception signal and the current perception signal be t0. The result of the previous position perception of the nth object is The result of the previous speed perception is The maximum acceleration of the object measured during continuous perception is

[0105] It should be understood that because the speed of radio signals is much greater than the speed of an object, t0 can be approximated as the time interval between the previous sensing signal and the echo signal corresponding to the current sensing signal being received by the communication base station. The results of the previous position sensing and the previous velocity sensing are both sensed in three-dimensional space, resulting in values for position and velocity in different dimensions.

[0106] Assume that the maximum acceleration of the nth object during this perception does not exceed b is a parameter that can be freely set according to the actual scene. The possible location range of the object during this perception is a spherical area:

[0107]

[0108] The center of the sphere represents the target object, the radius of the sphere represents the range of position change of the target object during this perception, and the distance between the center of the sphere and the origin of the coordinate system is and the sphere radius They are expressed as follows:

[0109]

[0110] The distance d from the nth object to the origin of the coordinate system during this perception is n The value range of can be expressed as follows:

[0111]

[0112] In the above formula (4), d n The value range of is the location domain of the target object.

[0113] In this embodiment, by first determining the maximum acceleration of the target object, and then determining the center position and radius of the spherical area of the target object in the preset spherical coordinate system, the distance range in which the target object may exist during this perception is obtained, which can reduce false positioning caused by multipath interference and improve the accuracy of object positioning.

[0114] Based on the above embodiment, when the spatial domain is a two-dimensional angle domain, step S31 may include steps B311 to B312:

[0115] Step B311, determining a conical angle domain in a preset spherical coordinate system according to the spherical area;

[0116] Step B312: Determine the two-dimensional angle domain of the target object according to the semi-apex angle of the conical angle domain and the two-dimensional angle of the center of the spherical region.

[0117] The target positioning device can determine the conical area corresponding to the range of azimuth and elevation angles of the spherical area relative to the origin O of the spherical coordinate system based on the spherical area obtained above, that is, the conical angle domain. The conical area takes all tangents from the origin O to the surface of the spherical area as the surface, and the ray from the origin O to the center of the sphere as the axis. The half-apex angle α of the conical area is n It can be expressed as the following formula:

[0118]

[0119] The pitch angle of the line connecting the center of the sphere to the origin O and azimuth This means that the target object is relative to the

[0120] The elevation angle and azimuth angle of the base station, where: and They can be expressed as the following formulas:

[0121]

[0122] It should be understood that the pitch angle of the cone axis is θ0 and the azimuth angle is When the cone half-apex angle is α, the cone angle domain can be expressed as follows in the polar coordinate system:

[0123]

[0124] The pitch angle of the target object obtained above and azimuth and the half-apex angle α of the conical region n Substituting into the above formula (8), we can obtain the two-dimensional angle domain where the nth object may exist during this perception, which can be expressed as follows:

[0125]

[0126] In this embodiment, the pitch angle and azimuth angle of the axis in the conical area are further limited by determining the half-apex angle of the conical area corresponding to the spherical area. The signal source direction is limited by the two-dimensional angle domain of the cone, and the position range of the target can be further limited in the subsequent signal processing process to reduce the calculation complexity and positioning accuracy.

[0127] Step S32, determining a received signal matrix according to the echo signal;

[0128] Step S33, processing the received signal matrix using a multiple signal classification algorithm according to the spatial domain union of the at least one target object to obtain an angle measurement value of the at least one target object;

[0129] It should be noted that in this embodiment, the multiple signal classification MUSIC algorithm is used to process the echo signal. Specifically, based on the echo signals of N target objects in the current perception scene, the two-dimensional angles of the N target objects relative to the communication base station are measured, where N is a positive integer not less than 1.

[0130] It should be understood that in order for the communication base station to be able to measure two-dimensional angles, the antenna array used by the communication base station in this embodiment must include more than three antennas, and the antennas cannot be arranged in a straight line. The echo signals reflected by each target object received by the communication base station antenna array are arranged in the time-space dimension to form a complex matrix, namely the received signal matrix, whose dimensions are M×K (M is the number of channels, i.e., the number of antennas in the communication base station antenna array, and K is the number of sample snapshots).

[0131] Specifically, the snapshots of the received signals of each antenna are arranged horizontally into row vectors, and the row vectors of different antennas are arranged vertically to form a received signal matrix. The received signal matrix can be expressed as follows:

[0132] Y=AS+N (10)

[0133] Among them, is a set of complex matrices of size U×V, where U and V are generally positive integers, then the matrix K is the number of received signal sampling snapshots, and M is the number of receiving antennas. A can be expanded into A=[a1,a2,...,a N ], a1, a2, ..., a N are the guidance vectors of the echo signals of the 1st, 2nd, ..., Nth target objects, with a size of M×1, n It can be expressed as the following formula:

[0134]

[0135] In the above formula, phase(m,n) is the phase difference of the received signal of the mth antenna in the nth steering vector relative to the zero phase reference point, m∈{1,2,...,M}, n∈{1,2,...,N}. For example, when a uniform circular array is used and the zero phase reference point is at the center of the circular array, Where j is the imaginary unit, r is the radius of the uniform circular array, c is the speed of light, and f0 is the center frequency of the signal. In addition, the matrix To strip the signal matrix of the phase information of the echo direction, is the Gaussian noise matrix.

[0136] The spatial domain union of the N target objects in the current perception scenario, that is, the two-dimensional angular domain union of the N target objects, is used as the spatial spectrum construction and spectral peak search range of the MUSIC algorithm. The MUSIC algorithm is applied to the matrix Y to measure the directions of the echo signals reflected by the N target objects, that is, the angular measurement values of the N target objects relative to the communication base station.

[0137] Step S34, performing beamforming on the echo direction corresponding to the angle measurement value of at least one target object in the echo signal to obtain at least one single-path echo signal;

[0138] Step S35: constructing an observation matrix of the at least one target object according to the single-path echo signal and the sensing signal;

[0139] Step S36 : Processing the measurement matrix using a multiple signal classification algorithm according to the spatial domain of the target object to obtain a distance measurement value of the at least one target object.

[0140] It should be noted that beamforming involves weighted summing of multi-channel received signals to enhance the signal strength in the target direction and suppress interference from other directions. Common beamforming algorithms include delayed-sum beamforming and adaptive beamforming.

[0141] Specifically, after obtaining the two-dimensional angles of N target objects relative to the communication base station in the current perception scenario, that is, the directions of the echo signals reflected by the N target objects, the target positioning device can perform beamforming on the echo signal directions corresponding to the angle measurement values of each target object, and try to make each beam contain only one single-path echo signal. This is equivalent to retaining only the signal in the echo direction reflected by each target object, filtering out the received signals in other directions, and thus screening out the single-path echo signals corresponding to each target object.

[0142] Then, the single-path echo signals corresponding to each target object are processed using the inverse Fourier transform algorithm, MUSIC algorithm, etc., and the distance between each target object and the base station is measured respectively to obtain the distances of N target objects relative to the communication base station in the current perception scenario.

[0143] Specifically, the target positioning device divides each RE data on the single-path echo signal corresponding to a single target object with the known RE data at the same position in the sensing signal transmitted by the aforementioned communication base station, thereby extracting the phase offset of each RE and forming the measurement matrix corresponding to the target object. For example, the measurement matrix corresponding to the echo signal of the nth object is as follows:

[0144]

[0145] Among them, K is the number of OFDM symbols, L is the number of subcarriers, is the approximate Doppler shift of the echo signal of the nth object, τ n is the signal propagation time of the echo signal of the nth object, T is the duration of an OFDM symbol, Δf is the subcarrier spacing, and f0 is the signal starting frequency. In addition, the observation matrix M n Can be expressed as the product of a set of column vectors and row vectors in

[0146] The target positioning device uses the target object's location domain represented by the above formula (4) as the spatial spectrum construction and spectrum peak search range of the MUSIC algorithm for a single target object, and calculates the matrix M n The MUSIC algorithm can be used to measure the angle measurement values of N target objects relative to the communication base station.

[0147] Finally, by combining the distance measurements of each target object relative to the communication base station and the two-dimensional angle measurements, the positions of the N objects relative to the center of the communication base station antenna array can be obtained and converted from spherical coordinates to rectangular coordinates using the following formula:

[0148]

[0149] in, is the three-dimensional rectangular coordinate of the nth object measured, is the spherical coordinate of the nth object measured.

[0150] This embodiment provides a target positioning method, comprising: transmitting a sensing signal to at least one target object, receiving an echo signal reflected by the sensing signal from the at least one target object; obtaining prior information of the at least one target object, and constructing at least one spatial domain of the target object based on the prior information, wherein the spatial domain includes at least one of a two-dimensional angle domain and a position domain; determining a received signal matrix based on the echo signal; processing the received signal matrix using a multiple signal classification algorithm based on a union of the spatial domains of the at least one target object to obtain an angle measurement value of the at least one target object; beamforming the echo direction corresponding to the angle measurement value of the at least one target object in the echo signal to obtain at least one single-path echo signal; constructing an observation matrix of the at least one target object based on the single-path echo signal and the sensing signal; processing the observation matrix using a multiple signal classification algorithm based on the spatial domain of the target object to obtain a distance measurement value of the at least one target object; and determining positioning information of the at least one target object based on the angle measurement value and the distance measurement value.

[0151] Through the above-mentioned scheme, this embodiment can construct the spatial domains of multiple target objects using prior information. Based on the spatial domains of the multiple target objects, combined with the MUSIC algorithm, the echo signals reflected by the target objects are first calculated for angle measurement. Then, beamforming is performed using the calculated angle measurement values to obtain a single-path echo signal corresponding to each target object. The MUSIC algorithm is then used to calculate the distance measurement based on the spatial domains of the multiple target objects. Compared with existing methods that use iterative optimization algorithms to reduce the computational complexity of the MUSIC spectrum peak search process, the target positioning method in this application does not rely on preset parameters and constructs the spatial domain of the target object based solely on prior perception information. This reduces the complexity of the MUSIC algorithm spectrum construction and peak search, ensuring accurate positioning of multiple targets while reducing the computational complexity of the positioning information measurement scheme, achieving a better balance between positioning performance and complexity. At the same time, because prior perception information typically changes with changes in the scene, the target positioning method in this application has greater applicability in different scenarios.

[0152] Based on the second embodiment of the present application, in the third embodiment of the present application, the same or similar contents as those in the above-mentioned second embodiment can be referred to the above introduction and will not be described in detail later. Figure 3 The step S33 includes steps S331 to S333:

[0153] Step S331 , using the union of the two-dimensional angle domains of the at least one target object as the first spatial spectrum range of the multiple signal classification algorithm;

[0154] Step S332, using the multiple signal classification algorithm to process the received signal matrix to construct an angle spectrum function;

[0155] Specifically, the target positioning device combines the coverage areas of all target objects in the current perception scene in the two-dimensional angle domain into a spatial range, that is, the two-dimensional angle domain union, where the angle value range of the nth object is as shown in formula (9), with s θ and The first spatial spectrum range of the MUSIC algorithm is constructed by respectively constructing the pitch angle and the azimuth angle sampling intervals used as the two-dimensional angle spectrum. The first spatial spectrum range refers to a search space used to constrain the MUSIC algorithm.

[0156] It should be noted that the MUSIC algorithm decomposes the received signal matrix into a signal subspace and a noise subspace, and uses the orthogonality of the two to construct a spatial spectrum function. The number of peaks in the spatial spectrum function is the same as the number of target objects, and the direction corresponding to the peak is the direction of the echo signal reflected by the target object.

[0157] In this embodiment, the target positioning device uses the MUSIC algorithm to perform angle measurement on the received signal matrices of multiple target objects. Therefore, the spatial spectrum function constructed by the MUSIC algorithm is called the angle spectrum function. Specifically, the covariance matrix of the received signal matrix is calculated, the covariance matrix is eigendecomposed, and the signal subspace and noise subspace of the received signal matrix are determined to construct the angle spectrum function.

[0158] Step S333 : performing a spectrum peak search on the angle spectrum function according to the first spatial spectrum range to determine an angle measurement value of the at least one target object.

[0159] Then, according to the angle search range limited by the first spatial spectrum range, s θ and The pitch angle and azimuth angle sampling intervals are used as the peak search intervals of the two-dimensional angular spectrum respectively. The number of peaks in the angular spectrum function is obtained by searching to determine the number of target objects in the current perception scene, and the direction of the echo signal reflected by the target object is determined by the direction corresponding to the peak.

[0160] Furthermore, based on the above embodiment, step S36 includes steps S361 to S364:

[0161] Step S361 , for each target object, determining a second spatial spectrum range of the multiple signal classification algorithm according to the location domain of the target object;

[0162] Specifically, since the single-path echo signal corresponding to the target object using the MUSIC algorithm is usually measured to obtain the signal delay, when constructing the second spatial spectrum range of the MUSIC algorithm, it is necessary to convert the position domain of the target object, that is, the position domain of the nth object corresponding to the previous formula (4), into a time delay range expression in the time domain for each target object in the current perception scene, and use this time delay range expression as the second spatial spectrum range for the MUSIC algorithm to solve the echo signal delay for the target object. Wherein, let c be the speed of light, the propagation time τ of the nth object echo signal n The range can be expressed as follows:

[0163]

[0164] Step S362, using the multiple signal classification algorithm to process the measurement matrix to construct a delay spectrum function;

[0165] In this embodiment, the target positioning device uses the MUSIC algorithm to perform delay measurement on the observation matrix corresponding to a single target object. Therefore, the spatial spectrum function constructed by the MUSIC algorithm is called the delay spectrum function. Specifically, the covariance matrix of the conjugate transposed matrix of the observation matrix is calculated, and the covariance matrix is eigendecomposed to determine its signal subspace and noise subspace, thereby constructing the delay spectrum function.

[0166] Specifically, by transforming the aforementioned vector m R is regarded as the steering vector in the MUSIC algorithm, and M n The conjugate transpose of The delay spectrum function can be constructed using the MUSIC algorithm.

[0167] Step S363: performing a spectrum peak search on the delay spectrum function according to the second spatial spectrum range to obtain a propagation time of the echo signal corresponding to the target object;

[0168] Step S364: Determine the distance measurement value of the target object according to the propagation time and the speed of light.

[0169] Then, according to the time delay search range limited by the second spatial spectrum range, τ The sampling interval used as the peak search interval of the delay spectrum is used to obtain the delay corresponding to the peak position in the delay spectrum function, and the propagation time of the echo signal corresponding to the target object is determined. Half of this propagation time multiplied by the speed of light can be used to obtain the distance d between the nth object and the base station. n , that is, the distance measurement value of the nth target object relative to the communication base station.

[0170] This embodiment provides a target positioning method that utilizes the spatial domain of multiple target objects to construct the spectral search range of the MUSIC algorithm's angle spectrum and delay spectrum. This method first performs angle measurement on the echo signals reflected by the target objects, and then performs distance measurement on the single-path echo signals corresponding to each target object. By reducing the complexity of MUSIC algorithm spectrum construction and spectrum peak search, it is possible to ensure accurate positioning of multiple targets while reducing the computational complexity of the positioning information measurement scheme, thereby achieving a better balance between positioning performance and complexity.

[0171] It should be emphasized that compared to the case where the construction and search process of the MUSIC algorithm spatial spectrum is not simplified, the target positioning method in this application has an optimization in terms of computational complexity. The sum of the computational complexity of the MUSIC algorithm for angle measurement and distance measurement in this target positioning method is as follows:

[0172]

[0173] The total computational complexity when the calculation is not simplified is as follows:

[0174]

[0175] Where P is the number of antennas in the antenna array, Q is the number of signal snapshots, and d min and d max They are respectively the minimum and maximum possible distances between all objects and the antenna array that need to be set in the existing method. Considering that the perception in the applicable scenario of this application is continuous, the time interval between two adjacent perceptions is generally sub-second, and the distribution of all objects to be perceived generally does not occupy the entire pitch angle range of -90° to 90° and the azimuth angle range of -90° to 90°, and the acceleration of the object generally does not exceed the acceleration of gravity. The range that a single base station can cover is generally hundreds of meters. It can be obtained that the angle range and distance range of object perception in this application can be limited to the following formula:

[0176]

[0177] In summary, the target positioning method in this application reduces the amount of computation for the object positioning process compared to existing methods, and the larger the possible angle and distance range between the object and the base station and the smaller the object acceleration, the more obvious the computational complexity advantage of the target positioning method in this application.

[0178] The present application provides a target positioning device, which includes: at least one transceiver, the transceiver being used to send a perception signal and receive an echo signal reflected by a target object from the perception signal, at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the target positioning method of the above-mentioned embodiment 1.

[0179] Reference below Figure 4 , which shows a schematic diagram of the structure of a target positioning device suitable for implementing an embodiment of the present application. The target positioning device in the present application includes a transceiver 510, a processor 500, a memory 520, and a program or instruction stored in the memory 520 and executable on the processor 500; when the processor 500 executes the computer program or instruction, the target positioning method applied to a communication base station is implemented. The transceiver 510 is used to receive and send data under the control of the processor 500. Figure 4In the embodiment, bus architecture 530 may include any number of interconnected buses and bridges, specifically linking together various circuits of transceiver 510, one or more processors represented by processor 500, and memory represented by memory 520. The bus architecture may also link together various other circuits such as peripheral devices, voltage regulators, and power management circuits. Transceiver 510 may be multiple components, including a transmitter and a receiver, providing a unit for communicating with various other devices over a transmission medium. Processor 500 is responsible for managing the bus architecture and general signal processing, and memory 520 may store data used by processor 500 when performing operations.

[0180] The target positioning device provided in this application, utilizing the target positioning method described in the aforementioned embodiments, can address the technical issue of the prior art's lack of a solution that balances the accuracy and complexity of multi-target positioning. Compared to the prior art, the target positioning device provided in this application achieves the same beneficial effects as the target positioning method described in the aforementioned embodiments. Other technical features of this target positioning device are the same as those disclosed in the aforementioned embodiments and are not further elaborated here.

[0181] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0182] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

[0183] The present application provides a computer-readable storage medium having computer-readable program instructions (ie, computer program) stored thereon, wherein the computer-readable program instructions are used to execute the target positioning method in the above embodiment.

[0184] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0185] The computer-readable storage medium may be included in the target positioning device, or may exist independently without being assembled into the target positioning device.

[0186] The computer-readable storage medium carries one or more programs. When the one or more programs are executed by a target positioning device, the target positioning device is caused to: send a perception signal to at least one target object; receive an echo signal reflected by the perception signal from the at least one target object; obtain prior information of the at least one target object, and process the echo signal based on the prior information to obtain an angle measurement value and a distance measurement value of the at least one target object; and determine the positioning information of the at least one target object based on the angle measurement value and the distance measurement value.

[0187] Computer program code for performing the operations of the present application may be written in one or more programming languages, or a combination thereof, including object-oriented programming languages such as Java, Smalltalk, C++, and conventional procedural programming languages such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on the remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0188] The flow charts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present application. In this regard, each box in the flow chart or block diagram can represent a module, program segment or a part of code, and the module, program segment or a part of code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order than that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented by a dedicated hardware-based system that performs the specified function or operation, or can be implemented by a combination of dedicated hardware and computer instructions.

[0189] The modules described in the embodiments of the present application may be implemented in software or hardware, wherein the name of a module does not necessarily limit the unit itself.

[0190] The computer-readable storage medium provided in this application stores computer-readable program instructions (i.e., a computer program) for executing the aforementioned target positioning method. This computer-readable storage medium can address the technical problem of the prior art lacking a solution that balances the accuracy and complexity of multi-target positioning. Compared to the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the target positioning method provided in the aforementioned embodiments, and are not further elaborated here.

[0191] The present application also provides a computer program product, comprising a computer program, which implements the steps of the target positioning method as described above when the computer program is executed by a processor.

[0192] The computer program product provided in this application can solve the technical problem that the existing technology lacks a solution that takes into account both the accuracy and complexity of multi-target positioning. Compared with the existing technology, the beneficial effects of the computer program product provided in this application are the same as those of the target positioning method provided in the above embodiment, and will not be repeated here.

[0193] The above description is only part of the embodiments of the present application and does not limit the patent scope of the present application. All equivalent structural transformations made by using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A target positioning method, characterized in that: The target positioning method is applied to a communication base station, and the target positioning method includes: sending a sensing signal to at least one target object; receiving an echo signal of the sensing signal reflected by the at least one target object; Acquiring prior information of the at least one target object, and processing the echo signal based on the prior information to obtain an angle measurement value and a distance measurement value of the at least one target object; The positioning information of the at least one target object is determined according to the angle measurement value and the distance measurement value.

2. The target positioning method according to claim 1, wherein: The step of obtaining the prior information of the at least one target object includes: Acquiring adjacent perception information of the at least one target object; Determine the prior information of the at least one target object based on the adjacent sensing information, where the prior information includes at least position and speed information of the target object.

3. The target positioning method according to claim 2, wherein: The step of processing the echo signal based on the prior information to obtain the angle measurement value and the distance measurement value of the at least one target object includes: Based on the prior information, construct at least one spatial domain of the target object, wherein the spatial domain includes at least one of a two-dimensional angle domain and a position domain; determining a received signal matrix according to the echo signal; Processing the received signal matrix using a multiple signal classification algorithm according to the spatial domain union of the at least one target object to obtain an angle measurement value of the at least one target object; Performing beamforming on an echo direction corresponding to an angle measurement value of at least one target object in the echo signal to obtain at least one single-path echo signal; constructing an observation matrix of the at least one target object according to the single-path echo signal and the sensing signal; The measurement matrix is processed using a multiple signal classification algorithm according to the spatial domain of the target object to obtain a distance measurement value of the at least one target object.

4. The target positioning method according to claim 3, wherein: The step of constructing at least one spatial domain of the target object based on the prior information comprises: Determining maximum acceleration information of the target object based on the position and velocity information of the target object; Determining a spherical area of the target object in a preset spherical coordinate system according to the target object position information, velocity information, and maximum acceleration information; The position domain of the target object is determined according to the center position and the radius of the spherical area.

5. The target positioning method according to claim 4, wherein: The step of constructing at least one spatial domain of the target object based on the prior information further includes: Determine a conical angle domain in a preset spherical coordinate system according to the spherical area; The two-dimensional angle domain of the target object is determined according to the semi-apex angle of the conical angle domain and the two-dimensional angle of the center of the spherical area.

6. The target positioning method according to claim 3, wherein: The step of processing the received signal matrix using a multiple signal classification algorithm based on the spatial domain union of the at least one target object to obtain the angle measurement value of the at least one target object includes: Using the union of the two-dimensional angle domains of the at least one target object as the first spatial spectrum range of the multiple signal classification algorithm; Processing the received signal matrix using the multiple signal classification algorithm to construct an angle spectrum function; According to the first spatial spectrum range, a spectrum peak search is performed on the angle spectrum function to determine an angle measurement value of the at least one target object.

7. The target positioning method according to claim 3, wherein: The step of processing the measurement matrix using a multiple signal classification algorithm according to the spatial domain of the target object to obtain the distance measurement value of the at least one target object includes: For each target object, determining a second spatial spectrum range of the multiple signal classification algorithm according to a location domain of the target object; Processing the measurement matrix using the multiple signal classification algorithm to construct a delay spectrum function; performing a spectrum peak search on the delay spectrum function according to the second spatial spectrum range to obtain a propagation time of an echo signal corresponding to the target object; A distance measurement value of the target object is determined based on the propagation time and the speed of light.

8. A target positioning device, characterized in that: The device comprises: a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the target positioning method according to any one of claims 1 to 7.

9. A storage medium, characterized in that: The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the target positioning method according to any one of claims 1 to 7 are implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the steps of the target positioning method according to any one of claims 1 to 7 are implemented.

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