CN110611895B - Indoor positioning method based on four-dimensional code mapping - Google Patents

Indoor positioning method based on four-dimensional code mapping Download PDF

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CN110611895B
CN110611895B CN201910913155.7A CN201910913155A CN110611895B CN 110611895 B CN110611895 B CN 110611895B CN 201910913155 A CN201910913155 A CN 201910913155A CN 110611895 B CN110611895 B CN 110611895B
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dimensional code
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antenna group
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CN110611895A (en
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王衍文
王世芳
马晓璠
王玉
马玥
周锋
马明娟
雷霄龙
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Xijing University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/14—Determining absolute distances from a plurality of spaced points of known location
    • 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
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • 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
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/024—Channel estimation channel estimation algorithms
    • H04L25/0242—Channel estimation channel estimation algorithms using matrix methods
    • 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
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management

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Abstract

The invention discloses an indoor positioning method based on four-dimensional code mapping, which comprises the following steps: (S100) carrying out Kronecker product on the horizontal dimension and vertical dimension characteristic vector matrixes to generate characteristic vector matrixes of the antenna groups, mapping the characteristic vector matrixes into four-dimensional codes, matching to obtain approximate code word four-dimensional codes and obtain pre-coding matrixes; (S200) performing beam forming on the base station transmitting signals according to the precoding matrix of the antenna group; (S300) the mobile terminal to be positioned and the antenna group form a virtual cell taking the mobile terminal as a center, a model virtual cell taking the mobile terminal as the center is formed with the mobile terminals around the virtual cell, an estimation function is constructed to obtain a positioning objective function, the positioning objective function is solved by adopting a nonlinear least square algorithm, and the coordinate when the positioning objective function takes the minimum value is the coordinate of the mobile terminal to be positioned. The method of the invention realizes indoor real-time space positioning by combining the beam matching of four-dimensional code mapping with a virtual cell cooperation mode.

Description

Indoor positioning method based on four-dimensional code mapping
Technical Field
The invention relates to an indoor positioning method, in particular to an indoor positioning method based on four-dimensional code mapping.
Background
With the rapid increase of data services and multimedia services, the demand for positioning is increasing. Such as: safety exits and elevators are quickly found in airport halls, exhibition halls and public places; finding parking places, parking and timing and charging indoors; the store pushes sales promotion, queuing reservation and payment services for the goods to the customer according to the location of the customer; emergency evacuation of large buildings, public safety, post-disaster rescue and the like.
Currently, other indoor positioning modes are researched and designed, for example, positioning is realized by using beam scanning, and chinese patent CN201710697495.1 discloses that indoor positioning is realized by using a multi-antenna tag in combination with beam scanning. However, the downward inclination angle of the antenna in the vertical direction in the two-dimensional beam is fixed, and only the spatial domain resource in the horizontal direction is utilized, so that the energy convergence is not high enough, and the coverage range is limited. Furthermore, chinese patent No. cn201610813895.x discloses a high-precision three-dimensional live-action indoor-outdoor integrated positioning method and apparatus, which comprises introducing a GPS positioning result into a room, selecting several reference points measurable in GPS coordinates in the room, and establishing a platform coordinate system with the reference points as coordinate origin; introducing a laser three-dimensional scanner at the reference point to acquire indoor three-dimensional point cloud information, and unifying the point clouds to a platform coordinate system; and further performing coordinate conversion on the coordinate system of the ultra-wideband indoor positioning system and the coordinate data to complete indoor target positioning. However, the positioning system has a complex structure, high cost and great implementation difficulty.
In order to increase the spatial resolution, a large-scale antenna array must be arranged in the base station, and the number of corresponding code words in the full beam set also reaches 102Even higher powers. Generally, when the channel information is used for beam matching, a traversal method for calculating and selecting optimal beams one by one is adopted, the method needs to traverse a codebook, time is consumed in the 3D beam forming calculation process, a beam matching method for mapping the beams into two-dimensional codes by precoding is also used, and in practical application, due to the diversity of the beams and the limitation of the capacity of the two-dimensional codes, the accurate corresponding relation between the beams and the 3D code words is difficult to form, so that the beams cannot accurately point to a target to be positioned.
In conclusion, the method is not suitable for indoor positioning with complex environment, accurate positioning and high real-time requirement.
Disclosure of Invention
The invention aims to provide an indoor positioning method based on four-dimensional code mapping, which solves the problem of complexity of the existing positioning method and realizes indoor real-time space positioning by combining beam matching of the four-dimensional code mapping with a virtual cell cooperation mode.
In order to achieve the above object, the present invention provides an indoor positioning method based on four-dimensional code mapping, the positioning system of the method comprises: baseband processing unit, distributed antenna group, mobile terminal Q to be positioned and M mobile terminals Q around the mobile terminal QlL is 1, … …, M is more than or equal to 4; wherein the set of distributed antennas comprises: at least 4 antenna groups Ant not on the same planekK is 1, … …, N is not less than 4, the antenna group AntkAll adopt planar array with array element number Mk×Nk，MkNumber of rows, N, of planar antenna arrayskThe number of columns of the planar antenna array; the base band processing unit is connected with each antenna group in the distributed antenna group through a feeder line, and performs corresponding processing after obtaining a sounding signal sent by the mobile terminal through the antenna group, and the method comprises the following steps:
(S100) the base station estimates a channel according to the received uplink sounding signal to obtain a horizontal dimension channel matrix, obtains a characteristic vector of the horizontal dimension channel matrix, and performs normalization processing to form a horizontal dimension characteristic vector matrix; obtaining the mobile terminal Q to be positioned to the antenna group Ant by estimating the channel estimation value through the uplink sounding signalkAngle of arrival theta of the vertical direction ofkForming a vertical dimension vector matrix; performing Kronecker product on the horizontal dimension and vertical dimension eigenvector matrix to generate an antenna group AntkCharacteristic vector matrix of (1), antenna group AntkThe eigenvector matrix is mapped into a four-dimensional code, the four-dimensional code is matched with a codebook four-dimensional code set to obtain an approximate codeword four-dimensional code, and thus an antenna group Ant is obtainedkThe precoding matrix W of (2);
(S200) according to the antenna group AntkThe precoding matrix W carries out beam forming on the signals transmitted by the base station;
(S300) to-be-positioned mobile terminal Q and antenna group AntkForming a virtual cell with a mobile terminal Q to be positioned as a center, wherein the mobile terminal Q to be positioned and M mobile terminals Q around the mobile terminal QlForming a normal virtual cell with the mobile terminal Q to be positioned as the center, respectively constructing an estimation function aiming at the virtual cell with the mobile terminal Q to be positioned as the center and the normal virtual cell, obtaining a positioning objective function according to the constructed estimation function, solving the positioning objective function by adopting a nonlinear least square algorithm, and taking the coordinate of the positioning objective function when the minimum value is taken as the coordinate of the mobile terminal Q to be positioned.
In step (S300), for the virtual cell, the estimation function is constructed as:
Figure GDA0002617533220000031
for a paravirtual cell, the constructed estimation function is:
Figure GDA0002617533220000032
in the formula, τVir_i1Is that the mobile terminal Q to be positioned reaches the ith (i is 2, … …, N) antenna group antenna and the 1 st antenna group antenna Ant in the virtual cell1The time difference of (a); tau isFan_l1Is that the mobile terminal Q to be positioned reaches the l (l ═ 2, … …, M) th mobile terminal Q in the paravirtual celll(l 2, … …, M) and the 1 st mobile terminal Q1The time difference of (a); the time difference τVir_i1And τFan_l1Obtaining signal transmission delay difference by detecting the time of each relevant peak value after the received signal is relevant; c is the propagation velocity of the spatial radio wave; dVir_iIs that the mobile terminal Q is to be positioned to the ith (i equals 1, … …, N) antenna group antenna Ant in the virtual celli(i is 1,2,3,4) is
Figure GDA0002617533220000033
i is 1,2,3,4, (x, y, z) is setCoordinates (x) of the mobile terminal Q to be positionedi,yi,zi) For the ith antenna group antenna AntiThe coordinates of (a); dFan_lIs that the mobile terminal Q to be positioned reaches the l (l ═ 1, … …, M) th mobile terminal Q in the paravirtual celll(l is 1, … …, M) is
Figure GDA0002617533220000034
l＝1,2,3,4，(xQl,yQl,zQl) For the first mobile terminal QlThe coordinates of (a).
The positioning objective function is:
J(x,y,z)＝DVir(x,y,z)+DFan(x,y,z)。
the coordinates of the mobile terminal Q to be positioned are as follows:
Figure GDA0002617533220000035
in the formula (I), the compound is shown in the specification,
Figure GDA0002617533220000036
the value of (x, y, z) at which the function reaches a minimum is shown.
Preferably, in step (S100), the antenna group Ant is usedkThe feature vector matrix is mapped into a four-dimensional code, and the mapping mode is as follows: mapping matrix elements into three-dimensional codes in sequence according to first column and second row
Figure GDA0002617533220000037
Then the three-dimensional code is put
Figure GDA0002617533220000041
The image is rotated by the angle of rotation
Figure GDA0002617533220000042
The rotation angle is the maximum arrival angle to obtain the four-dimensional codee。
Preferably, in step (S100), the antenna group Ant is usedkIs matched with the four-dimensional code set of the codebook by mapping the four-dimensional code into the eigenvector matrixThe process comprises the following steps:
(S151) setting the initial recognition rate to η;
(S152) determining whether a corresponding four-dimensional code is searched in a four-dimensional code set corresponding to the precoding codebook: if so, the four-dimensional code is the solved four-dimensional code; if not, continue the step (S153);
(S153) setting the recognition rate to be reduced by one step;
(S154) judging that the recognition rate eta is the lowest level: if not, go to step (S152); if yes, go to step (S155);
(S155) sets the four-dimensional code corresponding to the wide beam as the sought four-dimensional code.
Preferably, in step (S100), the codebook four-dimensional code set is obtained by mapping and rotating a pair of codewords in a precoding codebook in a protocol in advance, and is stored for retrieval.
Preferably, in step (S100), the vector matrix in the vertical dimension is:
Figure GDA0002617533220000043
where λ is the wavelength of the radio wave; d is the antenna spacing; theta1、θ2、θ3、θ4Are respectively a mobile terminal Q to an antenna group Ant to be positioned1、Ant2、Ant3And Ant4Angle of arrival of (d).
Preferably, in step (S200), if the base station transmitting signal is S, the base station transmitting signal beam is: w · s.
Preferably, the base station transmitting signal comprises: simple antenna group serial number and antenna group position coordinates.
Preferably, the transmission mode of the base station transmission signal includes: each antenna group AntkRespectively transmit respective serial numbers and position information, or all antenna groups AntkThe sequence number and the position information of each antenna group are transmitted.
The indoor positioning method based on the four-dimensional code mapping solves the problem that the existing positioning method is complex, and has the following advantages that:
(1) the positioning method of the invention realizes indoor real-time space positioning by utilizing the beam matching of four-dimensional code mapping and combining a virtual cell cooperation mode, can overcome the problems of complex positioning method, lower positioning precision and the like existing in the current indoor positioning, and has the characteristics of wide coverage, good anti-multipath effect, strong expandability and the like;
(2) according to the positioning method, the four-dimensional code is utilized, one dimension is added on the basis of the three-dimensional code, more data can be represented, and more information capacity is provided, so that the coding capacity is further improved, the method is more suitable for being mapped with large-capacity 3D precoding, and the 3D precoding construction method based on the four-dimensional code mapping can be used for quickly and accurately searching out code words matched with a channel in a precoding codebook, so that the time delay is reduced, and the overall performance of a system is improved;
(3) the positioning method of the invention is based on the cooperative positioning of the virtual cell and the model virtual cell, and better solves the problem of large result deviation caused by the non-convergence of the conventional solving equation; meanwhile, due to the introduction of the positioning information of the model virtual cell, even if the antenna group antenna in the positioning area fails or the traditional positioning algorithm fails due to reasons such as shielding, the positioning can still be performed through the model virtual cell, so that the robustness of the positioning algorithm is improved.
Drawings
Fig. 1 is a schematic structural diagram of an indoor positioning system based on four-dimensional code mapping according to the present invention.
Fig. 2 is a flowchart of an indoor positioning method based on four-dimensional code mapping according to the present invention.
FIG. 3 is a flow chart of constructing a precoding matrix based on four-dimensional code mapping according to the present invention.
FIG. 4 is a flowchart illustrating matching of four-dimensional codes with four-dimensional code sets of a codebook according to the present invention.
FIG. 5 is a diagram illustrating the effect of mapping matrix elements into four-dimensional codes according to the present invention.
Fig. 6 is a flow chart of estimating three-dimensional coordinates based on the cooperation of a virtual cell and a model virtual cell according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
An indoor positioning method based on four-dimensional code mapping is shown in fig. 1, which is a schematic structural diagram of an indoor positioning system based on four-dimensional code mapping according to the present invention, and the system includes: a baseband processing unit (BBU), a distributed antenna group (Ant), a mobile terminal Q to be positioned and surrounding terminals Q1、Q2、Q3And Q4. Wherein the distributed antenna group is formed by Ant1、Ant2、Ant3And Ant4The BBU is connected with 4 antenna groups in the indoor distributed antenna groups through feeder lines.
Antenna setting group Antk(k is 1,2, …,4, k is antenna group number), all adopt the planar array, the array element number is Mk×Nk，MkIs the number of rows of the planar antenna array, and Mk＝4(k＝1,2,…,4)，NkIs the number of columns of the planar antenna array, and Nk＝4(k＝1,2,…,4)。
The antenna group respectively receives sounding signals sent by the terminal Q, and the BBU carries out corresponding processing after obtaining the sounding signals sent by the terminal Q through the antenna group. As shown in fig. 2, it is a flowchart of an indoor positioning method based on four-dimensional code mapping according to the present invention, the method includes:
(S100) the base station estimates a channel according to the received uplink sounding signal (the BBU in the base station receives the uplink sounding signal), and generates a precoding matrix, as shown in fig. 3, which is a flow chart for constructing a precoding matrix based on four-dimensional code mapping according to the present invention, and includes:
(S110) a horizontally-dimensional channel matrix is obtained.
Specifically, antenna group Ant is derived from uplink channel estimationk(k＝1,2,…,4)Channel matrix H in horizontal dimensionh,1,Hh,2,…,Hh,4. Wherein Hh,mAnd (m ═ 1,2,3,4) denotes a channel matrix from the mth row antenna to the mobile terminal Q to be positioned. Solving a channel matrix H in a horizontal dimensionh,m(m is 1,2,3,4) horizontal dimension feature vector γh,m(m 1,2,3,4) for the feature vector γ in horizontal dimensionh,mCarrying out normalization processing to form a horizontal dimension characteristic vector matrix which is:
Figure GDA0002617533220000061
(S120) a vertical-dimensional channel matrix is obtained.
Specifically, the terminal Q to antenna group Ant is obtained from the uplink channel estimation value (i.e. the uplink channel estimation obtains the corresponding value)k(k is 1,2, …,4) angle of arrival θ in the vertical directionk(k ═ 1,2, …,4), forming a vertical dimension vector matrix of:
Figure GDA0002617533220000062
where λ is the wavelength of the radio wave and d is the antenna pitch.
(S130) solving a horizontal dimension feature vector matrixhAnd a vector matrix of vertical dimensionvAnd (5) obtaining a vector matrix by the Kronecker product.
In particular, a feature vector matrix of horizontal dimensionhAnd the feature vector matrix of the vertical dimensionvThe Kronecker product of (a) is:
Figure GDA0002617533220000071
wherein kron () is the Kronecker product sign, when Mk＝4，NkWhen 4(k is 1,2, …,4), the vector matrix is a 16 × 16 order matrix.
(S140) mapping the vector matrix into a four-dimensional codee。
Specifically, the mapping manner is: mapping matrix elements into three-dimensional codes in sequence according to first column and second row
Figure GDA0002617533220000072
Then the three-dimensional code is put
Figure GDA0002617533220000073
The image is rotated by the angle of rotation
Figure GDA0002617533220000074
Namely, the rotation angle is the maximum arrival angle to obtain the four-dimensional codee。
(S150) the four-dimensional code obtainedeAnd codebook four-dimensional code set
Figure GDA0002617533220000075
Matching to obtain approximate code word four-dimensional code
Figure GDA0002617533220000076
Thereby obtaining an antenna group AntkAnd (k is 1,2, …,4) precoding matrix W.
Codebook four-dimensional code set
Figure GDA0002617533220000077
A pair of code words in a precoding codebook in a protocol is mapped and rotated in advance to obtain the code words, and the code words are stored for retrieval. The following may be used: let Wp、Wq(p ≠ q) is a pair of code words in a precoding codebook, and W isp、WqAnd carrying out Kronecker product, and mapping and rotating the product result according to the sequence and the row to form the four-dimensional code. The rotation angle can be quantized to a specific value when constructing the four-dimensional codebook set, and the value does not affect the beam effect, such as taking the rotation angle to be 3 °.
Thus, the codebook four-dimensional code set
Figure GDA0002617533220000078
Each of the four-dimensional codes corresponds to a pair of code words plus a specific rotation angle in the precoding codebook. In practical application, the required precoding W can be timely and accurately obtained by using the fast search characteristic of the four-dimensional code.
Specifically, as shown in fig. 4, a flowchart of matching the four-dimensional code with the four-dimensional code set of the codebook according to the present invention is shown, and in step (S150), the process of matching the four-dimensional code with the four-dimensional code set of the codebook includes:
(S151) setting the initial recognition rate η, if it is set that η is 90%, that is, the matching accuracy is not less than 90%;
(S152) whether a corresponding four-dimensional code is searched in a four-dimensional code set corresponding to the precoding codebook, if so, turning to the step (S156), wherein the four-dimensional code is the solved four-dimensional code; if not, go to step (S153);
(S153) the recognition rate eta-10%;
(S154) determining that the recognition rate η is the lowest level (if the recognition rate η is 50%), if not, proceeding to step (S152); if yes, go to step (S155);
(S155) the four-dimensional code corresponding to the wide beam is set, and if it is indicated that the appropriate four-dimensional code is not searched, the four-dimensional code corresponding to the wide beam is taken, since the wide beam has a wider coverage characteristic, although some gain is lost.
(S156) obtaining the four-dimensional code (approximate code word four-dimensional code)
Figure GDA0002617533220000081
)。
Further, the implementation process of precoding mapping rotation to four-dimensional code is as follows:
assuming the horizontal dimension eigenvector matrix as:
Figure GDA0002617533220000082
the vertical dimension vector matrix is:
Figure GDA0002617533220000083
in the above formula, get
Figure GDA0002617533220000084
To findh、vThe Kronecker product of (a) is:
Figure GDA0002617533220000085
Figure GDA0002617533220000091
in the above formula, j is an imaginary unit and is a 16 × 4 matrix.
The matrix elements are mapped into four-dimensional codes in rows and columns, the rotation angle θ is argmax (pi/6, pi/4) is pi/4, and the mapping result is shown in fig. 5 (the effect of the color QR code cannot be shown because the drawing is colorless).
(S200) beamforming is performed according to the precoding matrix.
Suppose the base station transmits a signal s ═ s1,s2,…,s4]Wherein the signal s1,s2,…,s4Are antenna groups Ant respectivelykAnd (k is 1,2, …,4), the transmitted signal beam of the base station is W.s.
In indoor positioning, the base station transmits signals, which are generally: the simple antenna group sequence number and the antenna group position coordinates can adopt the following transmission modes: antenna group Antk(k ═ 1,2, …,4) transmitting different signals, i.e. transmitting respective sequence numbers and position information; antenna group AntkThe same signal is transmitted (k 1,2, …,4), i.e. the serial number and the position information of all antenna groups are transmitted on each antenna group.
And (S300) detecting and spatially positioning the mobile terminal.
As shown in fig. 6, a flowchart for estimating three-dimensional coordinates based on virtual cell and model virtual cell cooperation includes:
(S310) to-be-positioned mobile terminal Q and four antenna groups Ant1、Ant2、Ant3A virtual cell taking a mobile terminal Q to be positioned as a center is formed, and the mobile terminal Q to be positioned and four mobile terminals Q around the mobile terminal Q are formed1、Q2、Q3And Q4And forming a model virtual cell taking the mobile terminal Q to be positioned as the center.
In particular, it is assumed that a position is to be determinedCoordinates of the mobile terminal Q are (x, y, z), and four antenna groups Ant1、Ant2、Ant3And Ant4Respectively is (x)1,y1,z1)、(x2,y2,z2)、(x3,y3,z3) And (x)4,y4,z4) (ii) a Mobile terminal Q and four antenna groups Ant to be positioned1、Ant2、Ant3And Ant4And forming a virtual cell taking the mobile terminal Q to be positioned as the center.
Four mobile terminals Q around mobile terminal Q to be positioned1、Q2、Q3And Q4Respectively have the coordinates of
Figure GDA0002617533220000092
And
Figure GDA0002617533220000093
and terminal Q1、Q2、Q3And Q4Is a known coordinate, which can be obtained using existing indoor positioning methods (terminal Q)1、Q2、Q3And Q4The coordinates of the mobile terminal Q to be positioned in cooperation) are not described herein, and a model virtual cell centered on the mobile terminal Q to be positioned is formed in a terminal-to-Device (D2D) manner.
(S320) an estimation function is constructed for a virtual cell and a paravirtual cell centered on the mobile terminal Q to be positioned.
Specifically, for the virtual cell, the constructed estimation function is:
Figure GDA0002617533220000101
for the above-mentioned paravirtual cell, the constructed estimation function is:
Figure GDA0002617533220000102
in the above formula, τVir_i1Is to be determinedLocating the mobile terminal Q to the ith (i is 2,3,4) antenna group antenna and the 1 st antenna group antenna Ant in the virtual cell1The time difference of (a); tau isFan_l1Is the terminal Q to the l (l ═ 2,3,4) th mobile terminal and the 1 st mobile terminal Q in the model virtual cell1The time difference of (a); time difference tauVir_i1And τFan_l1The time delay difference of signal transmission is obtained by detecting the time of each correlation peak value after the correlation of the received signal, c is the propagation speed of the space radio wave, and c is 3 × 108M/s; dVir_iIs the terminal Q to the ith (i ═ 1,2,3,4) antenna group antenna Ant in the virtual celli(i is 1,2,3,4) and dVir_i＝√(x-xi)2+(y-yi)2+(z-zi)2，i＝1,2,3,4；dFan_lIs terminal Q to the l (l ═ 1,2,3,4) th terminal Q in the model virtual celll(l is 1,2,3,4) is
Figure GDA0002617533220000103
And (S330) constructing a positioning objective function, and solving to obtain the coordinate of the terminal Q.
Specifically, a positioning objective function is constructed as:
J(x,y,z)＝DVir(x,y,z)+DFan(x,y,z)。
solving the objective function by adopting a nonlinear least square algorithm, so that (x, y, z) when the positioning objective function J (x, y, z) takes the minimum value is the coordinate of the terminal Q, namely:
Figure GDA0002617533220000104
wherein the content of the first and second substances,
Figure GDA0002617533220000105
the value of (x, y, z) at which this latter equation is minimized is shown.
The positioning method can overcome the problems of complex positioning method, low positioning precision and the like existing in the current indoor positioning, has the characteristics of wide coverage, good multipath resistance effect, strong expandability and the like, and can realize indoor real-time three-dimensional positioning.
While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.

Claims (8)

1. An indoor positioning method based on four-dimensional code mapping, the positioning system aimed at by the method comprises: baseband processing unit, distributed antenna group, mobile terminal Q to be positioned and M mobile terminals Q around the mobile terminal QlL is 1, … …, M is more than or equal to 4; wherein the set of distributed antennas comprises: at least 4 antenna groups Ant not on the same planekK is 1, … …, N is not less than 4, the antenna group AntkAll adopt planar array with array element number Mk×Nk，MkNumber of rows, N, of planar antenna arrayskThe number of columns of the planar antenna array; the base band processing unit is connected with each antenna group in the distributed antenna group through a feeder line, and performs corresponding processing after obtaining a sounding signal sent by the mobile terminal through the antenna group, and the method is characterized by comprising the following steps:
(S100) the base station estimates a channel according to the received uplink sounding signal to obtain a horizontal dimension channel matrix, obtains a characteristic vector of the horizontal dimension channel matrix, and performs normalization processing to form a horizontal dimension characteristic vector matrix; obtaining the mobile terminal Q to be positioned to the antenna group Ant by estimating the channel estimation value through the uplink sounding signalkAngle of arrival theta of the vertical direction ofkForming a vertical dimension vector matrix; performing Kronecker product on the horizontal dimension and vertical dimension eigenvector matrix to generate an antenna group AntkCharacteristic vector matrix of (1), antenna group AntkThe eigenvector matrix is mapped into a four-dimensional code, the four-dimensional code is matched with a codebook four-dimensional code set to obtain an approximate codeword four-dimensional code, and thus an antenna group Ant is obtainedkThe precoding matrix W of (2);
(S200) according to the antenna group AntkThe precoding matrix W carries out beam forming on the signals transmitted by the base station;
(S300) to-be-positioned mobile terminal Q and antenna group AntkForming a virtual cell with a mobile terminal Q to be positioned as a center, wherein the mobile terminal Q to be positioned and M mobile terminals Q around the mobile terminal QlForming a normal virtual cell with a mobile terminal Q to be positioned as a center, respectively constructing an estimation function aiming at the virtual cell with the mobile terminal Q to be positioned as the center and the normal virtual cell, obtaining a positioning objective function according to the constructed estimation function, solving the positioning objective function by adopting a nonlinear least square algorithm, and taking the coordinate of the positioning objective function when the minimum value is taken as the coordinate of the mobile terminal Q to be positioned;
in step (S300), for the virtual cell, the estimation function is constructed as:
Figure FDA0002644410500000011
for a paravirtual cell, the constructed estimation function is:
Figure FDA0002644410500000021
in the formula, τVir_i1Is that the mobile terminal Q is positioned to the ith antenna group antenna and the 1 st antenna group antenna Ant in the virtual cell1Wherein i is 2, … …, N; tau isFan_l1Is that the mobile terminal Q to be positioned reaches the first mobile terminal Q in the model virtual celllWith the 1 st mobile terminal Q1Wherein l is 2, … …, M; the time difference τVir_i1And τFan_l1Obtaining signal transmission delay difference by detecting the time of each relevant peak value after the received signal is relevant; c is the propagation velocity of the spatial radio wave; dVir_iIs that the mobile terminal Q is positioned to the ith antenna group antenna Ant in the virtual celliWhere i in the ith is 1, … …, N; antenna group antenna AntiWherein i is 1,2,3,4,
Figure FDA0002644410500000022
(x, y, z) is the set coordinates of the mobile terminal Q to be positioned, (x)i,yi,zi) For the ith antenna group antenna AntiThe coordinates of (a); dFan_lIs that the mobile terminal Q to be positioned reaches the first mobile terminal Q in the model virtual celllWhere l is 1, … …, M,
Figure FDA0002644410500000023
Figure FDA0002644410500000028
for the first mobile terminal QlThe coordinates of (a);
the positioning objective function is:
J(x,y,z)＝DVir(x,y,z)+DFan(x,y,z)；
the coordinates of the mobile terminal Q to be positioned are as follows:
Figure FDA0002644410500000024
in the formula (I), the compound is shown in the specification,
Figure FDA0002644410500000025
the value of (x, y, z) at which the function reaches a minimum is shown.
2. The indoor positioning method based on four-dimensional code mapping of claim 1, wherein in step (S100), the antenna group Ant is transmittedkThe feature vector matrix is mapped into a four-dimensional code, and the mapping mode is as follows: mapping matrix elements into three-dimensional codes in sequence according to first column and second row
Figure FDA0002644410500000026
Then the three-dimensional code is put
Figure FDA0002644410500000027
The image is rotated and revolvedTurning angle
Figure FDA0002644410500000031
The rotation angle is the maximum arrival angle to obtain the four-dimensional codee。
3. The indoor positioning method based on four-dimensional code mapping of claim 2, wherein in step (S100), the antenna group Ant is transmittedkThe process of matching the four-dimensional code mapped by the eigenvector matrix with the four-dimensional code set of the codebook comprises the following steps:
(S151) setting the initial recognition rate to η;
(S152) determining whether a corresponding four-dimensional code is searched in a four-dimensional code set corresponding to the precoding codebook: if so, the four-dimensional code is the solved four-dimensional code; if not, continue the step (S153);
(S153) setting the recognition rate to be reduced by one step;
(S154) judging that the recognition rate eta is the lowest level: if not, go to step (S152); if yes, go to step (S155);
(S155) sets the four-dimensional code corresponding to the wide beam as the sought four-dimensional code.
4. The four-dimensional code mapping based indoor positioning method of claim 1, wherein in step (S100), the codebook four-dimensional code set is obtained by mapping and rotating a pair of codewords in a precoding codebook in a protocol in advance, and is stored for retrieval.
5. The indoor positioning method based on four-dimensional code mapping of claim 1, wherein in step (S100), the vertical vector matrix is:
Figure FDA0002644410500000032
where λ is the wavelength of the radio wave; d is the antenna spacing; theta1、θ2、θ3、θ4Are respectively a mobile terminal Q to an antenna group Ant to be positioned1、Ant2、Ant3And Ant4Angle of arrival of (d).
6. The indoor positioning method based on four-dimensional code mapping of claim 1, wherein in step (S200), the base station transmitting signal is S, and then the base station transmitting signal beam is: w · s.
7. The four-dimensional code mapping based indoor positioning method of claim 6, wherein the base station transmits signals comprising: simple antenna group serial number and antenna group position coordinates.
8. The method as claimed in claim 7, wherein the transmission manner of the base station transmitting signal comprises: each antenna group AntkRespectively transmit respective serial numbers and position information, or all antenna groups AntkThe sequence number and the position information of each antenna group are transmitted.
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