CN111083637B - High-precision positioning method for combined MIMO base station and non-MIMO base station - Google Patents

Abstract

The invention belongs to the technical field of wireless positioning, and in particular relates to a high-precision positioning method combining a MIMO base station and a non-MIMO base station. The method includes the following steps: obtaining the base station identifier and the number of antennas of the MIMO communication base station; sending the PRS positioning reference signal by the MIMO communication base station; obtaining the base station identifier of the non-MIMO assisted positioning base station; sending the PRS positioning reference signal by the non-MIMO assisted positioning base station ; The mobile user equipment receives the positioning reference signal waveform from the MIMO communication base station and the non-MIMO assisted positioning base station, selects the MIMO communication base station as the reference base station, and calculates the signal arrival time difference and signal arrival angle; according to the obtained signal arrival angle and signal arrival angle The time difference hybrid solves for the location of the mobile user equipment. The invention reduces the required quantity of the array antenna, reduces the hardware requirements of the base station, and saves the cost. The signal quality and the number of available base stations have been improved, and the stability of positioning has been improved. The positioning accuracy of the mobile user equipment is improved.

Description

High-precision positioning method for joint MIMO base station and non-MIMO base station

technical field

The invention belongs to the technical field of wireless positioning, and in particular relates to a high-precision positioning method combining a MIMO base station and a non-MIMO base station.

Background technique

At present, positioning and navigation technology has become an important basic technology for social security and national economic development. Although the positioning technology represented by Beidou and GPS is very mature, it is difficult to apply in indoor scenarios due to signal occlusion attenuation. However, the needs of indoor positioning are very extensive, such as: parking lot vehicle management, mine tunnel monitoring, human and unmanned system navigation in modern logistics large warehouses. With the continuous improvement of 5G communication standards, the era of 5G communication has arrived, and the high-precision indoor positioning technology in the environment of dense indoor networking of 5G networks is of great positive significance for the entire field of positioning and navigation. There are many technical methods in the field of positioning today, but in the existing 5G scenario, due to the need to save costs, the general practice is that only the communication base station will use a full-featured multiple-input multiple-output MIMO base station to meet the needs of high-speed communication. In order to achieve Multiple coverage of positioning signals will supplement non-MIMO base stations to improve positioning accuracy. However, the research on joint MIMO base station and non-MIMO base station for indoor positioning has not been reported yet.

The MIMO base station provides convenience for the measurement of the angle of arrival of the signal, but the method of positioning the angle of arrival of the signal is traditionally used in the field of phased array radar. In the indoor scene application, the error will increase significantly due to the multipath effect, and the effect of practical application is poor. . Representative achievements include the patent number CN201910410716.1 "A high-performance hybrid positioning method based on angle and signal arrival time difference estimation and its realization device", which proposed a signal model based on bistatic radar, which improved the target position Estimated accuracy. The representative achievements of the positioning method based on the time difference of arrival of the signal include: "An indoor three-dimensional positioning method for ultra-wideband" with the patent number of CN201910803709.8, which proposes a signal time difference of arrival for ultra-wideband TDOA indoor three-dimensional positioning Method, the three-dimensional position of the label estimated by the Chan algorithm is used to weight the residual value to improve the accuracy of indoor positioning; Patent No. CN201910530686.8 "A Positioning Method Based on the Difference of Arrival Angle", a selection method is proposed. A method of calculating the position of a mobile station from the signal arrival angle AOA of the three base stations. However, under the condition of 5G communication, the high-precision positioning method of joint MIMO base station and non-MIMO base station has not been specially studied, and it is still a relatively new field.

To sum up, it is concluded that the existing indoor positioning methods still have the following shortcomings:

(1) The positioning method based on the angle of arrival of the signal has high requirements on hardware conditions, and a large number of base stations need to be equipped with array antennas to obtain the angle of arrival of the signal.

(2) The positioning method based on the arrival time difference of the signal In the indoor environment, the near-field error is large, and the positioning accuracy is not high.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a high-precision positioning method for a joint MIMO base station and a non-MIMO base station.

A high-precision positioning method for a joint MIMO base station and a non-MIMO base station, the method includes the following steps:

Step 1: Obtain the base station identifier and the number of antennas of the MIMO communication base station;

Step 2: the PRS positioning reference signal is sent by the MIMO communication base station;

Step 3: Obtain the base station identifier of the non-MIMO assisted positioning base station;

Step 4: the PRS positioning reference signal is sent by the non-MIMO-assisted positioning base station;

Step 5: the mobile user equipment receives the positioning reference signal waveform from the MIMO communication base station and the non-MIMO assisted positioning base station, and selects the MIMO communication base station as the reference base station, and calculates the signal arrival time difference and the signal arrival angle;

Step 6: Calculate the position of the mobile user equipment according to the obtained signal arrival angle and the signal arrival time difference.

The step 2 includes the following steps:

Step 2.1: The MIMO communication base station generates a three-dimensional time-frequency resource grid of the MIMO communication base station based on the number of subcarriers, OFDM symbols and the number of physical antennas;

Step 2.2: According to the three-dimensional time-frequency resource grid of the MIMO communication base station, generate a PRS positioning reference signal of the MIMO communication base station based on the base station identifier and the frequency shift;

Step 2.3: According to the PRS positioning reference signal of the MIMO communication base station, generate the PRS positioning reference signal index of the MIMO communication base station based on the base station identifier and the frequency shift;

Step 2.4: According to the PRS positioning reference signal index of the MIMO communication base station, perform resource mapping of the MIMO communication base station and transmit signals using OFDM modulation.

The three-dimensional time-frequency resource grid (n1, n2, n3) of the MIMO communication base station described in step 2.1 is expressed as the following formula:

n1=N1×NDLRB; n2=N2×LCP; n3=NP;

Among them, NDLRB is the number of resource blocks in the downlink; LCP is the length of the cyclic prefix; NP is the number of antennas; N1 is the number of subcarriers; N2 is the number of OFDM symbols;

The PRS positioning reference signal sequence of the MIMO communication base station described in step 2.2 is expressed as the following formula:

c _init =(2 ¹⁶ ×(7×(Ns+1)+l+1)×(2×CID+1)+2×(Lcp+Vshift))mod 2

Wherein, frequency shift Vshift=(CID+f(PAID))mod x; X1 sequence: x1(i+31)=(x1(i+3)+x1(i))mod 2; X2 sequence: x2(i+ 31)=(x2(i+3)+x2(i+2)+x2(i+1)+x2(i))mod 2, Cinit is the initial pseudo-random sequence, CID is the base station identifier, PAID is the physical Antenna identifier; f(PAID) is a function of PAID; A mod B means that A performs a remainder operation on B;

The PRS positioning reference signal index of the MIMO communication base station described in step 2.3 is expressed as the following formula:

m'＝m+NDLRB-NPRSRB；NDLRB为下行链路资源块数量，NPRSRB为下行链路PRS信号带宽。Among them, k=6×(m+NDLRB-NPRSRB)+(6-1+Vshift)mod6; m is a sequence of non-negative integers from 0 to (2×NPRSRB-1);

m'=m+NDLRB-NPRSRB; NDLRB is the number of downlink resource blocks, and NPRSRB is the downlink PRS signal bandwidth.

The step 4 includes the following steps:

Step 4.1: The non-MIMO-assisted positioning base station generates a two-dimensional time-frequency resource grid of the non-MIMO-assisted positioning base station based on the number of subcarriers and OFDM symbols;

Step 4.2: According to the two-dimensional time-frequency resource grid of the non-MIMO assisted positioning base station, generate the PRS positioning reference signal of the non-MIMO assisted positioning base station based on the base station identifier;

Step 4.3: According to the PRS positioning reference signal of the non-MIMO assisted positioning base station, generate the PRS positioning reference signal index of the non-MIMO assisted positioning base station based on the base station identifier;

Step 4.4: According to the PRS positioning reference signal index of the non-MIMO assisted positioning base station, perform resource mapping of the non-MIMO assisted positioning base station and transmit signals using OFDM modulation.

The two-dimensional time-frequency resource grid (n1, n2) of the non-MIMO assisted positioning base station described in step 4.1 is expressed as the following formula:

n1=N1×NDLRB; n2=N2×LCP

Among them, NDLRB is the number of resource blocks in the downlink; LCP is the length of the cyclic prefix; NP is the number of antennas; N1 is the number of subcarriers; N2 is the number of OFDM symbols.

The signal arrival time difference described in step 5 is expressed as the following formula:

Among them, R(τ) is the cross-correlation sequence, T is the observation time of the received signal, r1(t) is the PRS positioning reference signal observation from the MIMO communication base station, and ri(t+τ) is the signal from the non- The PRS positioning reference signal of the MIMO-assisted positioning base station is observed, and the time of the peak extreme value of the obtained cross-correlation sequence R is the signal arrival time difference.

The position (x, y) of the mobile user equipment described in step 6 is expressed as the following formula:

Among them, t _k,1 is the signal arrival time difference between the non-MIMO assisted positioning base station with base station identifier k and the MIMO communication base station with base station identifier 1, μ _k,1 is the error in the measurement process of signal arrival time, μ _θ is the error in the signal arrival angle measurement process, (x ₁ , y ₁ ) is the coordinate of the MIMO communication base station, θ is the signal arrival angle of the positioning reference signal sent by the MIMO communication base station to the mobile user equipment, i is the base station identifier, c is the speed of light, and D _i is the straight-line distance from the base station whose base station identifier is i to the mobile user equipment.

The beneficial effects of the present invention are:

(1) Reduce the required number of array antennas, reduce the hardware requirements of the base station, and save costs.

(2) The mixed layout method of MIMO communication base stations and multiple non-MIMO assisted positioning base stations is adopted to improve the signal quality and the number of available base stations, and improve the stability of positioning.

(3) Improve the positioning accuracy of the mobile user equipment.

Description of drawings

FIG. 1 is a schematic flowchart of a base station side high-precision positioning method for a joint MIMO base station and a non-MIMO base station.

FIG. 2 is a schematic flowchart of a mobile user equipment side of a high-precision positioning method for a joint MIMO base station and a non-MIMO base station.

FIG. 3 is a schematic diagram of base station deployment according to an embodiment of the present invention.

FIG. 4 is a schematic flowchart of generating a PRS positioning reference signal based on a base station identifier and a frequency shift by a MIMO base station according to the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings.

The present invention aims to propose a high-precision positioning method combining a MIMO communication base station and a non-MIMO assisted positioning base station. information.

Since the hardware cost of the MIMO array antenna base station is high, which is not conducive to large-scale deployment, the present invention proposes a method, which takes into account the accuracy of AOA positioning and the economy of TDOA positioning. It can improve the positioning accuracy while reducing the cost of base station deployment; make full use of 5G communication base stations to save channel resources.

Figure 1 shows the basic flow chart of the high-precision positioning method of the joint MIMO base station and non-MIMO base station, including the specific steps as follows:

Step (1) obtains the base station identifier and the number of antennas of the MIMO communication base station;

In this embodiment, the number of MIMO communication base stations is 1, the MIMO communication base station identifier is 1, and the number of antennas is 2;

Step (2) Further, the MIMO communication base station in the step 1 sends a PRS (Positioning Reference Signal) positioning reference signal based on the base station identifier and the frequency shift;

Step (3) obtaining the base station identifier of the non-MIMO assisted positioning base station;

As shown in FIG. 3 , in this embodiment, the number of non-MIMO base stations is 3, the identifiers of non-MIMO assisted positioning base stations are 10, 11, and 12 respectively, and the number of antennas is all 1;

Step (4) Further, the PRS positioning reference signal is sent by the non-MIMO assisted positioning base station in the step 3:

Step (5) the mobile user equipment receives the positioning reference signal waveform from the MIMO communication base station and the non-MIMO assisted positioning base station, and selects the MIMO communication base station as the reference base station, and calculates the signal arrival time difference and the signal arrival angle;

In step (6), the position of the mobile user equipment is mixed and calculated based on the angle of arrival of the signal and the time difference of arrival of the signal obtained in the step 5.

The method for sending the PRS positioning reference signal by the MIMO communication base station in the foregoing step (2) specifically further includes the following steps:

Step (2.1) generates a three-dimensional time-frequency resource grid based on the number of subcarriers, OFDM symbols and physical antennas by the MIMO communication base station in step 2; the scale of the time-frequency resource grid (n1, n2, n3) is as follows: The formula is determined:

n1=12×NDLRB; n2=14×LCP; n3=NP;

where NDLRB is the number of resource blocks in the downlink; LCP is the length of the cyclic prefix; NP is the number of antennas;

In this embodiment, the number of subcarriers is 12, the number of OFDM symbols is 14, the NDLRB value is 100, the Lcp value is 1, and the NP value is 2;

In step (2.2), the MIMO communication base station in the step 2 generates a PRS positioning reference signal based on the base station identifier and frequency shift, and its signal sequence is determined by the following formula:

c _init =(2 ¹⁶ ×(7×(Ns+1)+l+1)×(2×CID+1)+2×(Lcp+Vshift))mod 2

Frequency shift Vshift=(CID+f(PAID))mod x;

X1 sequence: x1(i+31)=(x1(i+3)+x1(i))mod 2;

X2 sequence: x2(i+31)=(x2(i+3)+x2(i+2)+x2(i+1)+x2(i))mod 2;

Among them, Cinit is the initial pseudo-random sequence, CID is the base station identifier, PAID is the physical antenna identifier; f(PAID) is the function of PAID; A mod B means that A performs a remainder operation on B;

Step (2.3) generates the PRS positioning reference signal index based on the base station identifier and the frequency shift by the MIMO communication base station in the step 2;

The reference signal index is determined by the following formula:

in,

k=6×(m+NDLRB-NPRSRB)+(6-1+Vshift)mod6;

m is a sequence of non-negative integers from 0 to (2×NPRSRB-1);

m'=m+NDLRB-NPRSRB;

NDLRB is the number of downlink resource blocks, and NPRSRB is the downlink PRS signal bandwidth;

In step (2.4), the MIMO communication base station in the step 2 performs resource mapping according to the PRS positioning reference signal index and transmits signals by OFDM modulation;

In this embodiment, OFDM modulation is used to perform inverse Fourier transform on resource elements on different subcarriers to obtain a modulated signal, the output of which is a complex exponential;

The method for sending a PRS positioning reference signal by a non-MIMO assisted positioning base station in the aforementioned step (4) specifically further includes the following steps:

Step (4.1) generates a two-dimensional time-frequency resource grid based on the number of subcarriers and the OFDM symbol by the non-MIMO-assisted positioning base station in the step 3;

The time-frequency resource grid size (n1, n2) is determined by the following formula:

n1=12×NDLRB; n2=14×LCP;

In this embodiment, the number of subcarriers is 12, the number of OFDM symbols is 14, the NDLRB value is 100, and the Lcp value is 1;

Step (4.2) generates a PRS positioning reference signal based on the base station identifier by the non-MIMO-assisted positioning base station in the step 3;

c _init =(2 ¹⁰ ×(7×(Ns+1)+l+1)×(2×CID+1)+2×(Lcp+CID))mod 2

X1 sequence: x1(i+31)=(x1(i+3)+x1(i))mod 2;

X2 sequence: x2(i+31)=(x2(i+3)+x2(i+2)+x2(i+1)+x2(i))mod 2;

Step (4.3) generates a PRS positioning reference signal index based on the base station identifier by the non-MIMO-assisted positioning base station in the step 3;

The reference signal index is determined by the following formula:

in,

k=6×(m+NDLRB-NPRSRB)+(6-1+Vshift)mod6;

m is a sequence of non-negative integers from 0 to (2×NPRSRB-1);

m'=m+NDLRB-NPRSRB;

In this embodiment, since the number of physical antennas of the non-MIMO base station is 1, the Vshift value of the non-MIMO base station is 0;

In step (4.4), the non-MIMO-assisted positioning base station in the step 3 performs resource mapping and transmits signals using OFDM modulation;

In the aforementioned step (5), the mobile user equipment receives the positioning reference signal waveform from the MIMO communication base station and the non-MIMO assisted positioning base station, and selects the MIMO communication base station as the reference base station, and calculates the signal arrival time difference and the method for the signal arrival angle, specifically: Also includes the following steps:

Step (5.1) The mobile user equipment calculates the angle of arrival of the signal by comparing the phase differences between the received PRS positioning reference signals sent by the MIMO communication base station;

The signal arrival angle θ between the MIMO communication base station array antenna and the mobile user equipment calculated by the mobile user equipment in this embodiment is shown in FIG. 3 ;

Step (5.2) The mobile user equipment obtains the signal arrival time difference by calculating the time of the peak extremum of the cross-correlation sequence of the received PRS positioning reference signal sent by the MIMO communication base station and the non-MIMO base station, which is specifically calculated by the following formula:

Specifically, in this embodiment, r1(t) is the PRS positioning reference signal observation from the MIMO communication base station, and r2(t), r3(t) and r4(t) are the three non-MIMO assisted positioning The PRS positioning reference signal of the base station is observed, and the time at which the peak extremum of the obtained cross-correlation sequence R is located is the signal arrival time difference;

As shown in FIG. 3 , the trajectory with a constant distance difference between the mobile user equipment and the two base stations is a hyperbola, so m-1 hyperbolas can be obtained in this embodiment, where m is the number of base stations 4;

In the aforementioned step (6), the method for hybridly calculating the position of the mobile user equipment further includes the following steps:

(6.1) From the angle of arrival of the signal obtained in the aforementioned step (5.1), the following equation is used to solve the position of the mobile user equipment:

In this embodiment, the signal arrival angle θ is shown in FIG. 3 ;

In step (6.2), the time difference of arrival of the signal obtained in the aforementioned step (5.2) is used to calculate the position of the mobile user equipment by using the following equation:

In this embodiment, i is the non-MIMO base station identifiers, which are 10, 11, and 12, respectively;

Step (6.3) Further, use the fusion position calculation algorithm based on the signal arrival angle and the signal arrival time difference to solve the position of the mobile user equipment, in this embodiment, specifically use the following equation to solve the position (x, y of the mobile user equipment) ):

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Any person who is familiar with this profession, without departing from the scope of the solution of the present invention, can use the technical content shown above to make a small amount of changes or modifications to equivalent examples of equivalent changes; but all content that does not depart from the technical solution of the present invention. , any simple modifications, equivalent changes and modifications made to the above embodiments according to the essence of the technical solutions of the present invention fall within the scope of the technical solutions of the present invention.

Claims (1)

1. A high-precision positioning method for a combined MIMO base station and a non-MIMO base station is characterized by comprising the following steps:

step 1: acquiring the number of physical antennas of the MIMO communication base station, and setting a base station identifier of the MIMO communication base station as 1;

step 2: the MIMO communication base station generates and transmits a first Positioning Reference Signal (PRS);

the MIMO communication base station generates three-dimensional time-frequency resource grids (n1, n2, n3) based on the number of subcarriers, OFDM symbols and the number of physical antennas, and generates a first Positioning Reference Signal (PRS) and an index thereof based on a base station identifier and a frequency shift of the MIMO communication base station; the MIMO communication base station performs resource mapping according to the generated index of the first positioning reference signal PRS and adopts OFDM modulation to transmit signals;

n1＝N1×NDLRB；n2＝N2×LCP；n3＝NP；

wherein NDLRB is the number of resource blocks in the downlink; LCP is the length of the cyclic prefix; NP is the physical antenna number of the MIMO communication base station; n1 is the number of subcarriers; n2 is the number of OFDM symbols;

and step 3: acquiring a base station identifier of a non-MIMO auxiliary positioning base station;

and 4, step 4: generating and transmitting a second Positioning Reference Signal (PRS) by the non-MIMO auxiliary positioning base station;

the non-MIMO assisted positioning base station generating a two-dimensional time-frequency resource grid (n1, n2) based on the number of subcarriers and OFDM symbols, and generating a second positioning reference signal, PRS, and its index based on a base station identifier of the non-MIMO assisted positioning base station; the non-MIMO auxiliary positioning base station performs resource mapping according to the generated index of the second positioning reference signal PRS and adopts OFDM modulation to transmit signals;

and 5: the method comprises the steps that mobile user equipment receives positioning reference signals from an MIMO communication base station and a non-MIMO auxiliary positioning base station, selects the MIMO communication base station as a reference base station, and calculates the time of a peak extreme value of a cross-correlation sequence of PRS positioning reference signals sent by the received MIMO communication base station and the non-MIMO auxiliary positioning base station to obtain a signal arrival time difference; calculating a signal arrival angle theta between an MIMO communication base station array antenna and mobile user equipment;

wherein R (τ) is a cross-correlation sequence; t is the observation time of the received signal; r1(t) is a PRS positioning reference signal observation from the MIMO communication base station; ri (t + τ) is observation of a PRS positioning reference signal from the non-MIMO auxiliary positioning base station, and the moment of a peak extreme value of the obtained cross-correlation sequence R is a signal arrival time difference;

step 6: resolving the position (x, y) of the mobile user equipment according to the obtained signal arrival angle and the signal arrival time difference;

wherein, t_k,1A signal arrival time difference for a non-MIMO assisted positioning base station with base station identifier k relative to a MIMO communication base station with base station identifier 1; mu.s_k,1Error in the signal arrival time measurement process for a non-MIMO assisted positioning base station with base station identifier k relative to a MIMO communications base station with base station identifier 1; mu.s_θError in the signal angle of arrival measurement process; i is a base station identifier, (x)₁,y₁) Coordinates for MIMO communication base stations, D_iA linear distance from a base station with a base station identifier of i to the mobile user equipment; and c is the speed of light.

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