CN114390463A - Indoor multi-target passive positioning method and system and electronic equipment - Google Patents

Indoor multi-target passive positioning method and system and electronic equipment Download PDF

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CN114390463A
CN114390463A CN202210101361.XA CN202210101361A CN114390463A CN 114390463 A CN114390463 A CN 114390463A CN 202210101361 A CN202210101361 A CN 202210101361A CN 114390463 A CN114390463 A CN 114390463A
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target
signal
intelligent
targets
positioning
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CN114390463B (en
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陈彦
张淦霖
张东恒
张冬
孙启彬
吴枫
吴曼青
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University of Science and Technology of China USTC
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University of Science and Technology of China USTC
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/33—Services specially adapted for particular environments, situations or purposes for indoor environments, e.g. buildings
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/04013—Intelligent reflective surfaces
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842—Weighted combining
    • H04B7/086—Weighted combining using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)

Abstract

The invention discloses an indoor multi-target passive positioning method, which comprises the following steps: respectively arranging an intelligent reflecting surface with an array element spacing of half wavelength and a uniform linear antenna array with an antenna spacing of half wavelength at a transmitting end and a receiving end of the WiFi equipment, wherein the intelligent reflecting surface is used for reflecting signals sent by the WiFi equipment; calculating a beam forming vector and a phase shift vector by using the WiFi signal received by the uniform linear antenna array and the WiFi signal reflected by the intelligent reflecting surface, optimizing the uniform linear antenna array and the intelligent reflecting surface, and acquiring the positioning information of a single target; and optimizing the phase of the intelligent reflecting surface and eliminating the signal interference of the positioned target by utilizing the positioning information of the positioned target so as to realize the positioning of other targets. The acquisition operation, optimization operation, elimination operation, and location operation are iteratively performed until all targets in the room are located. The invention also discloses an indoor multi-target passive positioning system and electronic equipment.

Description

Indoor multi-target passive positioning method and system and electronic equipment
Technical Field
The invention belongs to the field of signal processing, and particularly relates to an indoor multi-target passive positioning method, an indoor multi-target passive positioning system and electronic equipment.
Background
Indoor passive positioning refers to accurate positioning indoors under the condition that people do not carry any equipment. Indoor positioning currently supports more and more location-based services and applications, including intrusion detection, elderly care, and real-time positioning of criminals, for example. However, existing vision-based localization techniques are limited by lighting conditions and privacy issues; the radar equipment often needs expensive special hardware design, and the deployment in real life is limited.
Since WiFi (wireless fidelity) devices are ubiquitous, commercial WiFi devices offer the possibility for passive indoor location estimation. In the prior art, WiFi device-based positioning methods mainly rely on the estimation of Angle of Arrival (AoA) or Time of flight (ToF). However, due to the limited bandwidth and the limited number of antennas of the commercial WiFi device, the resolution of the estimated AoA and ToF is usually low, so that the positioning method based on the WiFi device in the prior art has the problems of low positioning accuracy, large limitation in the practical application process, and the like.
Disclosure of Invention
In view of the above, the present invention provides an indoor multi-target passive positioning method, system and electronic device, so as to solve at least one of the above problems.
According to an embodiment of the invention, an indoor multi-target passive positioning method is provided, which comprises the following steps:
respectively arranging an intelligent reflecting surface with an array element spacing of half wavelength and a uniform linear antenna array with an antenna spacing of half wavelength at a transmitting end and a receiving end of the WiFi equipment, wherein the intelligent reflecting surface is used for reflecting signals sent by the WiFi equipment;
calculating a beam forming vector and a phase shift vector by using the WiFi signal received by the uniform linear antenna array and the WiFi signal reflected by the intelligent reflecting surface, optimizing the uniform linear antenna array and the intelligent reflecting surface, and acquiring the positioning information of a single target;
optimizing the phase of the intelligent reflecting surface and eliminating the signal interference of the positioned target by utilizing the positioning information of the positioned target to realize the positioning of other targets;
the acquisition operation, optimization operation, elimination operation, and location operation are iteratively performed until all targets in the room are located.
According to an embodiment of the present invention, the calculating a beamforming vector and a phase shift vector and optimizing the uniform linear antenna array and the intelligent reflective surface, wherein the obtaining of the positioning information of the single target includes:
dividing an indoor space into a plurality of subspaces;
calculating a beam forming vector of the uniform linear antenna array of each subspace and a phase shift vector of the intelligent reflecting surface;
configuring an intelligent reflecting surface according to the phase shift vector of the intelligent reflecting surface to obtain a plurality of paths of echo signals;
superposing the multiple echo signals by using a beam forming vector to obtain the echo signal of a single target;
in a continuous time period, the echo signals of a single target are subjected to signal processing to eliminate interference signals of indoor inactive targets, and receiving signals of the single target are obtained;
by comparing the strength of the received signals, the subspace with the maximum signal strength is taken as the spatial position of the single target.
According to an embodiment of the present invention, the dividing the indoor space into the plurality of subspaces includes:
performing primary partition on the indoor space by using a multistage space partition method to obtain a plurality of primary subspaces;
and selecting a subspace with the maximum signal amplitude from the primary subspace to carry out secondary segmentation to obtain a plurality of subspaces.
According to an embodiment of the present invention, the beamforming vector described above is represented by formula (1):
Figure BDA0003492564390000021
wherein the content of the first and second substances,
Figure BDA0003492564390000022
denotes the beamforming vector of the nth receive antenna of the (x, y) -th subspace, uniform linear antenna array, j denotes the complex signal, λ denotes the signal wavelength, dTO(x, y) denotes a distance from the transmitting antenna to the (x, y) th subspace,
Figure BDA0003492564390000023
representing the distance of the (x, y) th subspace to the nth receive antenna.
According to an embodiment of the present invention, the above-described phase shift vector configuration is represented by formula (2):
Figure BDA0003492564390000031
wherein the content of the first and second substances,
Figure BDA0003492564390000032
a phase shift vector representing the (x, y) -th subspace, the m-th intelligent reflective surface element, j represents the complex signal, λ represents the signal wavelength,
Figure BDA0003492564390000033
representing the distance of the (x, y) th subspace to the m-th intelligent reflective surface element,
Figure BDA0003492564390000034
indicating the distance of the transmitting antenna to the mth smart reflective surface element.
According to an embodiment of the present invention, the optimizing the phase of the intelligent reflective surface and eliminating the signal interference of the located target by using the location information of the located target, and the locating of other targets includes:
dividing an indoor space into a plurality of subspaces;
calculating beam forming vectors and phase shift vectors of a plurality of subspaces, and superposing the beam forming vectors and the phase shift vectors to obtain echo signals of the plurality of subspaces;
optimizing the phase shift vector of the intelligent reflecting surface according to the spatial position information of the positioned target to minimize the signal of the positioned target and acquiring the echo signal of the optimized target;
minimizing the echo signal of the positioned target to obtain a minimized return signal of the positioned target;
calculating echo signals of other targets and echo signals of indoor inactive targets in continuous time to obtain echo signals of other targets for eliminating multipath interference;
and performing multi-path interference elimination on the echo signals of the optimized targets, comparing the signals of the subspaces to obtain the spatial position of the subspace with the maximum signal intensity, and positioning other targets.
According to an embodiment of the present invention, the echo signal of the located target includes a signal transmitted by the WiFi device and directly reaching the target and a signal transmitted via the intelligent reflection surface and reaching the target;
the minimization processing of the echo signal of the located target is expressed by formula (3) and formula (4):
min|sd| (3)，
Figure BDA0003492564390000035
wherein phi ismaxFor limiting the amplitude of small phase perturbations, Δ q represents the small phase perturbations added to the smart reflective surface.
According to an embodiment of the present invention, solving equations (3) and (4) includes a semi-positive definite programming method, an interior point method, and a eigenvalue decomposition method.
According to an embodiment of the present invention, there is provided an indoor multi-target positioning system including:
the arrangement module is used for respectively arranging an intelligent reflection surface with an array element spacing of half wavelength and a uniform linear antenna array with an antenna spacing of half wavelength at a transmitting end and a receiving end of the WiFi equipment, wherein the intelligent reflection surface is used for reflecting signals sent by the WiFi equipment;
the calculation optimization module is used for calculating a beam forming vector and a phase shift vector by utilizing the WiFi signals received by the uniform linear antenna array and the WiFi signals reflected by the intelligent reflection surface, optimizing the uniform linear antenna array and the intelligent reflection surface and acquiring the positioning information of a single target;
the multi-target positioning module is used for optimizing the phase of the intelligent reflecting surface and eliminating the signal interference of the positioned target by utilizing the positioning information of the positioned target so as to realize the positioning of other targets;
and the iteration module is used for iteratively executing the acquisition operation, the optimization operation, the elimination operation and the positioning operation until all targets in the room are positioned.
According to an embodiment of the present invention, there is provided an electronic apparatus including:
one or more processors;
a storage device for storing one or more programs,
wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to perform the above-described method.
The positioning method provided by the invention can eliminate multipath interference in an indoor environment, separate signals reflected by different targets, improve the spatial resolution of equipment and realize accurate positioning of multiple targets.
Drawings
FIG. 1 is a flow chart of an indoor multi-target passive positioning method according to an embodiment of the invention;
FIG. 2 is a schematic diagram of a scenario of an indoor multi-target passive positioning method according to an embodiment of the present invention;
FIG. 3 is a flow chart of obtaining single target location information according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of multi-level positioning in a single-object scenario, according to an embodiment of the present invention;
FIG. 5 is a flow chart for implementing additional target location according to an embodiment of the present invention;
FIG. 6 is a schematic illustration of iterative localization in multiple object scenarios, according to an embodiment of the present invention;
FIG. 7 is a schematic diagram illustrating the effect of the interference target elimination method using small phase perturbation according to the embodiment of the present invention;
FIG. 8 is a schematic track diagram of a single target located by the locating method of the present invention;
FIG. 9 is a schematic track diagram of two targets located by the locating method according to the embodiment of the present invention;
FIG. 10 is a schematic track diagram of three targets located by the locating method according to the embodiment of the present invention;
FIG. 11 is a schematic diagram of an indoor multi-target positioning system according to an embodiment of the present invention;
fig. 12 is a block diagram of an electronic device suitable for implementing an indoor multi-target passive location method according to an embodiment of the present invention.
Detailed Description
In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.
Channel State Information (CSI) in WiFi devices describes the attenuation and phase shift experienced by a signal in an indoor environment. The motion, breathing, etc. of the indoor target (e.g., a person) can cause the received WiFi signal to change accordingly, thereby providing the possibility of using the WiFi signal to locate the indoor target.
An Intelligent Reflective Surface (IRS) is a digitally controlled metasurface consisting of a large number of small passive elements, each of which can independently achieve phase control of an incident signal by varying an applied control voltage. Unlike the traditional phased array which requires high power consumption and high hardware cost, the intelligent reflecting surface has lower power consumption and implementation cost by passively reflecting the input signal. In addition, smart reflective surfaces have other advantages such as full-duplex mode and flexible deployment characteristics. By virtue of the large number of low-cost controllable elements, the intelligent reflective surface provides a new degree of freedom, which can break through the low resolution limit of conventional commercial WiFi devices without any changes to the existing infrastructure.
Indoor multi-target location a common scenario is the location of multiple target characters indoors. One of the challenges in positioning in indoor multi-person scenarios is multipath interference. Static interference signals in an indoor environment are often stronger than signals reflected by people, and great interference is caused to the positioning of a human body. In addition, in a multi-person scene, signals reflected by different persons interfere with each other, and due to different distances, the energy of signals reflected by a far person is much weaker than that of a near person, so that the reflection of a far target is blurred and difficult to detect. Therefore, in order to accurately locate the position of the human body, the signals reflected by the individual human bodies are first separated from the received signals.
In the technical scheme of the invention, the collection, storage, use, processing, transmission, provision or application of the related personal positioning data all conform to the regulations of related laws and regulations, and are executed under the condition of acquiring the authorization of the related person to be positioned, necessary security measures are taken, and the customs of the public order is not violated.
The invention provides an indoor multi-target passive positioning method and system. The method comprises the steps that an intelligent reflecting surface and an antenna array are arranged on WiFi equipment, the intelligent reflecting surface is used as a passive radar for auxiliary positioning, and the intelligent reflecting surface and the receiving antenna array are jointly optimized by maximizing the signal amplitude difference between a moving target and multipath interference, so that accurate positioning of an indoor single target is realized; meanwhile, the positioned targets are utilized to optimize the phase of the intelligent reflecting surface, eliminate the signal interference of the positioned targets, realize the positioning of other targets, and repeatedly execute the optimization and elimination operations until all the targets in the room are accurately positioned.
Fig. 1 is a flowchart of an indoor multi-target passive positioning method according to an embodiment of the invention.
As shown in fig. 1, the indoor multi-target passive positioning method includes operations S110 to S140.
In operation S110, an intelligent reflective surface with a half-wavelength array element spacing and a uniform linear antenna array with a half-wavelength antenna spacing are respectively disposed at a transmitting end and a receiving end of the WiFi device, where the intelligent reflective surface is used for reflecting a signal sent by the WiFi device.
The intelligent reflection surface is used for reflecting signals sent by the WiFi equipment and can be regarded as a passive phase control radar; meanwhile, the intelligent reflection surface is arranged at the transmitting end of the WiFi equipment, so that the signals sent by the WiFi equipment can be reflected before the uniform linear antenna array receives the signals sent by the WiFi equipment.
In operation S120, a beam forming vector and a phase shift vector are calculated and the uniform linear antenna array and the intelligent reflection surface are optimized by using the WiFi signal received by the uniform linear antenna array and the WiFi signal reflected by the intelligent reflection surface, so as to obtain positioning information of a single target;
the signal received by the uniform linear antenna array comprises two aspects: the signal transmitted by the WiFi equipment and directly reaching an indoor target is reflected by the indoor target; secondly, after the signal which is transmitted by the intelligent reflection surface and reaches the indoor target, the signal is reflected by the indoor target; due to the fact that the two signals are different in phase, amplitude and the like, the joint optimization of the intelligent reflecting surface and the receiving antenna array can be achieved by maximizing the signal amplitude difference between the moving target and the multipath interference, and then the accurate positioning of the first person is achieved.
In operation S130, the positioning information of the positioned target is used to optimize the phase of the intelligent reflective surface and eliminate the signal interference of the positioned target, so as to position other targets;
the positioning information of the located target, that is, the positioning information of the single target obtained in operation S120, includes the spatial position information of the located target, and by using the spatial position information of the located target, the intelligent reflection surface, such as the phase of the intelligent reflection surface, may be effectively optimized, so as to optimize the WiFi signal reflected by the intelligent reflection surface, and thus implement signal separation and detection of the uniform linear antenna array on other indoor targets.
In operation S140, the acquisition operation, the optimization operation, the elimination operation, and the localization operation are iteratively performed until all targets in the room are localized.
By acquiring the positioning information of the target to be positioned, optimizing the configuration of the intelligent reflecting surface, positioning the subspace of the next target by using the optimized intelligent reflecting surface, and after eliminating the multipath interference of the positioned target and other indoor inactive targets, positioning other targets to be positioned can be realized. The above operations are repeatedly executed until the detected signal strength is lower than the noise threshold value, so that all the targets in the room are positioned.
The indoor multi-target passive positioning method can realize positioning under the scene of multi-target, multi-noise and multi-interference signals by using the intelligent reflection surface to assist positioning. Meanwhile, the positioning method provided by the embodiment of the invention not only can utilize WiFi equipment, but also can utilize any equipment with signal transmitting and receiving functions; further, the indoor target may include a human or other activity target.
Fig. 2 is a schematic diagram of an indoor multi-target passive positioning method according to an embodiment of the invention.
The positioning method according to the embodiment of the present invention is further described with reference to fig. 2.
As shown in fig. 2, the above positioning method uses a transmitter to transmit a signal, and reflects the signal through an intelligent reflective surface to reach a target (e.g. a movable, non-static target such as a human being) in two paths, wherein the direct path does not pass through the reflection of the intelligent reflective surface, and the transmission path of the intelligent reflective surface passes through the reflection of the intelligent reflective surface; the receiver not only receives the two signals transmitted by the target, but also receives the signal reflected by a static reflector (an indoor inactive target). The signal of the moving target can be effectively separated by processing the multipath interference, and the indoor moving target can be positioned by processing the signal of the moving target.
Fig. 3 is a flow chart of obtaining single target location information according to an embodiment of the present invention.
As shown in fig. 3, operation S310 to operation S360 are included.
Dividing an indoor space into a plurality of subspaces in operation S310;
in operation S320, a beamforming vector of the uniform linear antenna array and a phase shift vector of the intelligent reflective surface for each subspace are calculated;
in operation S330, configuring an intelligent reflection surface according to the phase shift vector of the intelligent reflection surface to obtain a plurality of echo signals;
in operation S340, superimposing the multiple echo signals by using the beamforming vector to obtain an echo signal of a single target;
in operation S350, acquiring a received signal of a single target by performing signal processing on an echo signal of the single target to remove an interference signal of an indoor inactive target for a continuous period of time;
in operation S360, a subspace having the greatest signal strength is regarded as a spatial location of a single object by comparing the strengths of the received signals.
According to an embodiment of the present invention, the dividing the indoor space into the plurality of subspaces includes:
performing primary partition on the indoor space by using a multistage space partition method to obtain a plurality of primary subspaces;
and selecting a subspace with the maximum signal amplitude from the primary subspace to carry out secondary segmentation to obtain a plurality of subspaces.
By multi-stage division of the indoor space, the calculation complexity can be reduced, and the real-time performance is improved. And firstly, roughly dividing the indoor space, and then selecting the subspace with the largest amplitude to perform fine-grained division, thereby realizing accurate positioning.
FIG. 4 is a diagram illustrating multi-level positioning in a single-object scenario, according to an embodiment of the present invention.
As shown in fig. 4, firstly, the indoor space is divided into a plurality of sub-spaces; then, the signal of each subspace is received, and the subspace with higher signal intensity is subjected to fine-grained scanning and segmentation, so that the spatial position information of a single target is obtained.
According to an embodiment of the present invention, the beamforming vector described above is represented by formula (1):
Figure BDA0003492564390000081
wherein the content of the first and second substances,
Figure BDA0003492564390000082
denotes the beamforming vector of the nth receive antenna of the (x, y) -th subspace, uniform linear antenna array, j denotes the complex signal, λ denotes the signal wavelength, dTO(x, y) denotes a distance from the transmitting antenna to the (x, y) th subspace,
Figure BDA0003492564390000083
representing the distance of the (x, y) th subspace to the nth receive antenna.
According to an embodiment of the present invention, the above-described phase shift vector configuration is represented by formula (2):
Figure BDA0003492564390000084
wherein the content of the first and second substances,
Figure BDA0003492564390000091
a phase shift vector representing the (x, y) -th subspace, the m-th intelligent reflective surface element, j represents the complex signal, λ represents the signal wavelength,
Figure BDA0003492564390000092
representing the (x, y) th subspace to the m-thThe distance of the surface elements can be reflected,
Figure BDA0003492564390000093
indicating the distance of the transmitting antenna to the mth smart reflective surface element.
The beam forming vector and the phase shift vector of the intelligent reflecting surface are calculated by the formula, the WiFi signals are transmitted to each subspace by using the calculated beam forming vector of the receiving end and the phase shift vector of the intelligent reflecting surface, echo signals are received, the characteristic that the signal of a moving target (such as a person) changes along with time without changing in static multipath is utilized, difference is made in a continuous time range to remove interference signals from a static reflector, and the subspace with the strongest received signal is selected as the position of the target through comparison, so that the indoor target can be positioned more effectively.
FIG. 5 is a flow chart for implementing other target location in accordance with an embodiment of the present invention.
As shown in fig. 5, the method for locating a plurality of other objects indoors using the located object includes operations S510 to S560.
In operation S510, an indoor space is divided into a plurality of subspaces.
The reflected signals of the plurality of subspaces formed by multi-stage division of the indoor space are different in phase, amplitude and the like, and the spatial position information of the indoor target can be acquired more conveniently.
In operation S520, beamforming vectors and phase shift vectors of a plurality of subspaces are calculated and added, and echo signals of the plurality of subspaces are obtained.
In operation S530, a phase shift vector of the intelligent reflective surface is optimized according to the spatial position information of the located target to minimize a signal of the located target, and an echo signal of the optimized target is acquired.
In operation S540, the echo signal of the located target is minimized, and the minimized echo signal of the located target is obtained.
In operation S550, echo signals of other targets from which multipath interference is removed are acquired by performing operations on echo signals of other targets and echo signals of indoor inactive targets in continuous time.
In operation S560, the echo signal of the optimized target is subjected to multipath interference cancellation, and the signals of the subspaces are compared to obtain the spatial position of the subspace with the maximum signal strength, so as to position other targets.
The method for positioning other indoor targets comprises the steps of firstly dividing an indoor space, calculating a beam forming vector of each subspace and a phase shift vector of an intelligent reflection surface according to the spatial position of each subspace, and adding small-phase disturbance delta q to the intelligent reflection surface according to the beam forming vector of a positioned target and the phase shift vector of the intelligent reflection surface, so that the minimization of a reflection signal of the positioned target is realized, and a foundation is laid for the subsequent multi-path interference elimination; meanwhile, transmitting WiFi signals and receiving echo signals to each subspace according to the obtained receiving end beam forming vector and the phase shift vector of the intelligent reflecting surface, performing difference making in a continuous time range to remove interference signals from the static reflector, and comparing and selecting the subspace with the strongest receiving signal as the position of the next target. By repeatedly performing the above-described localization method, when the detected signal strength is below the noise threshold, all objects (active, non-stationary objects, e.g. people) in the room have been localized.
FIG. 6 is a schematic diagram of iterative localization in multiple object scenarios, according to an embodiment of the present invention.
As shown in fig. 6, in each iteration, the spatial position information of the target located last time is fully utilized, the received signals of other targets are obtained through the uniform linear antenna array, and the phase shift vector of the intelligent reflection surface is optimized, so that the new target is located; in the process of each iterative positioning, multipath interference elimination is carried out, and the signal interference of the positioned target and the static inactive target is eliminated, so that the accuracy of target positioning can be improved, and the timeliness of positioning can also be improved.
According to an embodiment of the present invention, the echo signal of the located target includes a signal transmitted by the WiFi device and directly reaching the target and a signal transmitted via the intelligent reflection surface and reaching the target;
the minimization processing of the echo signal of the located target is expressed by formula (3) and formula (4):
min|sd| (3)，
Figure BDA0003492564390000101
wherein phi ismaxFor limiting the amplitude of small phase perturbations, Δ q represents the small phase perturbations added to the smart reflective surface.
According to the embodiment of the invention, solving the formula (3) and the formula (4) comprises Semi-definite programming (SDP), an interior point method and a eigenvalue decomposition method, and the phase shift vector q ═ Δ q × q of the intelligent reflection surface can be obtained by using the methods to solve0。
Fig. 7 is a schematic diagram illustrating the effect of the interference target elimination method using small phase perturbation according to the embodiment of the present invention, where a is before optimization and b is after optimization.
As can be seen from fig. 7, the method for eliminating the small-phase-disturbance interference target according to the embodiment of the present invention can effectively eliminate multipath interference, including but not limited to signal interference of a located target, signal interference of a static inactive target, and the like.
Fig. 8 is a schematic track diagram for locating a single target by using the locating method of the embodiment of the present invention.
Fig. 9 is a schematic track diagram for positioning two targets by using the positioning method according to the embodiment of the present invention.
Fig. 10 is a schematic track diagram for positioning three targets by using the positioning method according to the embodiment of the present invention.
Referring to fig. 8 to fig. 10, the positioning method provided by the embodiment of the present invention can be used to accurately position a single target, and can also be used to accurately position multiple targets under the condition that multiple targets coexist.
FIG. 11 is a schematic diagram of an indoor multi-target positioning system according to an embodiment of the present invention.
As shown in FIG. 11, the system 1100 includes a placement module 1110, a computational optimization module 1120, a multi-objective positioning module 1130, and an iteration module 1140.
The arrangement module 1110 is configured to arrange an intelligent reflection surface with a half-wavelength array element spacing and a uniform linear antenna array with a half-wavelength antenna spacing at a transmitting end and a receiving end of the WiFi device, respectively, where the intelligent reflection surface is used to reflect a signal sent by the WiFi device;
a calculation optimization module 1120, configured to calculate a beamforming vector and a phase shift vector and optimize the uniform linear antenna array and the intelligent reflective surface by using the WiFi signal received by the uniform linear antenna array and the WiFi signal reflected by the intelligent reflective surface, so as to obtain positioning information of a single target;
a multi-target positioning module 1130, configured to optimize a phase of the intelligent reflection surface and eliminate signal interference of the positioned target by using positioning information of the positioned target, so as to position other targets;
an iteration module 1140 for iteratively performing the acquisition operation, the optimization operation, the elimination operation, and the location operation until all targets in the room are located.
The positioning system provided by the embodiment of the invention can eliminate multipath interference in an indoor environment, separate signals reflected by different targets, improve the spatial resolution of equipment and realize accurate positioning of multiple targets.
Fig. 12 is a block diagram of an electronic device suitable for implementing an indoor multi-target passive location method according to an embodiment of the present invention.
As shown in fig. 12, an electronic apparatus 1200 according to an embodiment of the present invention includes a processor 1201 which can perform various appropriate actions and processes in accordance with a program stored in a Read Only Memory (ROM)1202 or a program loaded from a storage section 1208 into a Random Access Memory (RAM) 1203. The processor 1201 may include, for example, a general purpose microprocessor (e.g., a CPU), an instruction set processor and/or associated chipset, and/or a special purpose microprocessor (e.g., an Application Specific Integrated Circuit (ASIC)), among others. The processor 1201 may also include on-board memory for caching purposes. The processor 1201 may include a single processing unit or multiple processing units to perform the different actions of the method flows according to embodiments of the present invention.
In the RAM 1203, various programs and data necessary for the operation of the electronic apparatus 1200 are stored. The processor 1201, the ROM 1202, and the RAM 1203 are connected to each other by a bus 1204. The processor 1201 performs various operations of the method flow according to the embodiments of the present disclosure by executing programs in the ROM 1202 and/or the RAM 1203. Note that the programs may also be stored in one or more memories other than the ROM 1202 and the RAM 1203. The processor 1201 may also perform various operations of method flows according to embodiments of the present invention by executing programs stored in the one or more memories.
Electronic device 1200 may also include input/output (I/O) interface 1205, according to an embodiment of the disclosure, input/output (I/O) interface 1205 also connected to bus 1204. The electronic device 1200 may also include one or more of the following components connected to the I/O interface 1205: an input section 1206 including a keyboard, a mouse, and the like; an output portion 1207 including a display device such as a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and the like, and a speaker; a storage section 1208 including a hard disk and the like; and a communication section 1209 including a network interface card such as a LAN card, a modem, or the like. The communication section 1209 performs communication processing via a network such as the internet. A driver 1210 is also connected to the I/O interface 1205 as needed. A removable medium 1211, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like, is mounted on the drive 1210 as necessary, so that a computer program read out therefrom is mounted into the storage section 1208 as necessary.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. An indoor multi-target passive positioning method comprises the following steps:
respectively arranging an intelligent reflecting surface with an array element spacing of half wavelength and a uniform linear antenna array with an antenna spacing of half wavelength at a transmitting end and a receiving end of the WiFi equipment, wherein the intelligent reflecting surface is used for reflecting signals sent by the WiFi equipment;
calculating a beam forming vector and a phase shift vector by using the WiFi signal received by the uniform linear antenna array and the WiFi signal reflected by the intelligent reflecting surface, optimizing the uniform linear antenna array and the intelligent reflecting surface, and acquiring the positioning information of a single target;
optimizing the phase of the intelligent reflecting surface and eliminating the signal interference of the positioned target by utilizing the positioning information of the positioned target to realize the positioning of other targets;
the acquisition operation, optimization operation, elimination operation, and location operation are iteratively performed until all targets within the room are located.
2. The method of claim 1, wherein said computing a beamforming vector and a phase shift vector and optimizing said uniform linear antenna array and said intelligent reflective surface, obtaining positioning information for a single target comprises:
dividing an indoor space into a plurality of subspaces;
calculating a beamforming vector of the uniform linear antenna array and a phase shift vector of the intelligent reflective surface for each of the subspaces;
configuring an intelligent reflecting surface according to the phase shift vector of the intelligent reflecting surface to obtain a plurality of paths of echo signals;
superposing the multiple echo signals by using the beam forming vector to obtain the echo signal of the single target;
in a continuous time period, the echo signals of the single target are subjected to signal processing to eliminate interference signals of indoor inactive targets, and received signals of the single target are obtained;
and comparing the strength of the received signals, and taking the subspace with the maximum signal strength as the spatial position of the single target.
3. The method of claim 2, wherein the partitioning the indoor space into a plurality of subspaces comprises:
performing primary segmentation on the indoor space by using a multi-level space segmentation method to obtain a plurality of primary subspaces;
and selecting a subspace with the maximum signal amplitude from the primary subspace to carry out secondary segmentation to obtain a plurality of subspaces.
4. The method of claim 2, wherein the beamforming vector is represented by equation (1):
Figure FDA0003492564380000021
wherein the content of the first and second substances,
Figure FDA0003492564380000022
denotes a beamforming vector of an nth receiving antenna of the uniform linear antenna array of an (x, y) th subspace, j denotes a complex signal, λ denotes a signal wavelength, dTO(x, y) denotes a distance from a transmitting antenna to the (x, y) th subspace,
Figure FDA0003492564380000023
represents a distance of the (x, y) th subspace to the nth receive antenna.
5. The method of claim 2, wherein the phase shift vector configuration is represented by equation (2):
Figure FDA0003492564380000024
wherein the content of the first and second substances,
Figure FDA0003492564380000025
a phase shift vector representing said (x, y) th subspace, the m-th intelligent reflective surface element, j representing a complex signal, λ representing a signal wavelength,
Figure FDA0003492564380000026
representing a distance of said (x, y) th subspace to said m-th intelligent reflective surface element,
Figure FDA0003492564380000027
representing the distance of said transmitting antenna to the m-th smart reflective surface element.
6. The method of claim 1, wherein the utilizing the positioning information of the target to optimize the phase of the intelligent reflective surface and eliminate signal interference of the positioned target, and the positioning of other targets is achieved by:
dividing an indoor space into a plurality of subspaces;
calculating beam forming vectors and phase shift vectors of the subspaces and superposing the beam forming vectors and the phase shift vectors to obtain echo signals of the subspaces;
optimizing the phase shift vector of the intelligent reflecting surface according to the spatial position information of the positioned target to minimize the signal of the positioned target and obtain the echo signal of the optimized target;
minimizing the echo signal of the positioned target to obtain a minimized return signal of the positioned target;
calculating the echo signals of the other targets and the echo signals of the indoor inactive targets in continuous time to obtain the echo signals of the other targets for eliminating the multipath interference;
and performing multi-path interference elimination on the echo signals of the optimized targets, comparing the signals of the subspaces, obtaining the spatial position of the subspace with the maximum signal intensity, and realizing the positioning of the other targets.
7. The method of claim 6, wherein the echo signals of the located target comprise signals transmitted by a WiFi device that directly reach the target and signals transmitted via the smart reflective surface that reach the target;
wherein, the minimizing process of the echo signal of the located target is expressed by formula (3) and formula (4):
min|sd| (3)，
Figure FDA0003492564380000031
wherein phi ismaxFor limiting the amplitude of small phase perturbations, Δ q represents the small phase perturbations added to the smart reflective surface.
8. The method of claim 7, wherein solving equations (3) and (4) includes a semi-positive programming method, an interior point method, and a eigenvalue decomposition method.
9. An indoor multi-target positioning system comprising:
the WiFi equipment comprises an arrangement module, a transmission module and a receiving module, wherein the arrangement module is used for respectively arranging an intelligent reflection surface with an array element spacing of half wavelength and a uniform linear antenna array with an antenna spacing of half wavelength at a transmission end and a receiving end of the WiFi equipment, and the intelligent reflection surface is used for reflecting signals sent by the WiFi equipment;
the calculation optimization module is used for calculating a beam forming vector and a phase shift vector by utilizing the WiFi signals received by the uniform linear antenna array and the WiFi signals reflected by the intelligent reflection surface, optimizing the uniform linear antenna array and the intelligent reflection surface and acquiring the positioning information of a single target;
the multi-target positioning module is used for optimizing the phase of the intelligent reflecting surface and eliminating the signal interference of the positioned target by utilizing the positioning information of the positioned target so as to realize the positioning of other targets;
an iteration module for iteratively performing the obtaining operation, the optimizing operation, the eliminating operation, and the locating operation until all targets in the room are located.
10. An electronic device, comprising:
one or more processors;
a storage device for storing one or more programs,
wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to perform the method of any of claims 1-8.
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