JP2019124597A - Position estimation method of radio terminal station and radio base station - Google Patents

Abstract

To estimate the position of a radio terminal station at high speed by measuring a radio wave arrival time between a radio base station and the radio terminal station while the radio base station is switching distributed antennas deployed in a distributed manner.SOLUTION: A position estimation method of a radio terminal station is used when a radio base station estimates the position of the radio terminal station in a system including the radio base station capable of transmission and reception by switching a plurality of distributed antennas deployed in a distributed manner and the radio terminal station for communicating with the radio base station. The position estimation method includes: a first step of the radio base station measuring a radio wave arrival time with the radio terminal station for each of the distributed antennas; and a second step of estimating the position of the radio terminal station by using the radio wave arrival time for each of the plurality of distributed antennas measured in the first step.SELECTED DRAWING: Figure 1

Description

  According to the present invention, in a wireless base station capable of switching distributed antennas disposed in a distributed manner, the position of the wireless terminal station is measured by measuring the radio wave arrival time between the wireless base station and the wireless terminal station for each distributed antenna. The present invention relates to a wireless terminal station position estimation method and wireless base station to be estimated.

  As a service to which ToA (Time of Arrival) which is a radio wave arrival time of a wireless signal is applied, there is a position providing service of a wireless terminal station in a wireless LAN system. For example, as shown in Non-Patent Document 1, there is a method of measuring radio wave arrival time between a wireless terminal station whose position is to be estimated and a plurality of wireless base stations as an example of implementation of the position providing service.

FIG. 4 shows a conventional wireless terminal station position estimation method.
In FIG. 4, a plurality of wireless base stations 50-1 to 50-3 exist around the wireless terminal station 40. The radio terminal station 40 first performs connection processing with the radio base station 50-1 (S11), transmits a measurement signal to the radio base station 50-1, and receives a response signal from the radio base station 50-1 (S12). ). The round trip delay time Tm1 is measured from the transmission start time of the measurement signal of the wireless terminal station 40 and the reception start time of the response signal from the wireless base station 50-1. Similarly, the wireless terminal station 40 performs connection processing with other wireless base stations 50-2 and 50-3, and calculates round trip delay times Tm2 and Tm3 from the transmission start time of the measurement signal and the reception start time of the response signal, respectively. (S13 to S16). Furthermore, the wireless terminal station 40 calculates the radio wave arrival times T1 to T3 from the round trip delay times Tm1 to Tm3 with the respective wireless base stations 50-1 to 50-3. Then, the position of the radio terminal station 40 is estimated from the position information of the plurality of radio base stations 50-1 to 50-3 and the radio wave arrival times T1 to T3 (S17).

M. Llombart, M. Ciurana, and F. Barcelo-Arroyo. "On the scalability of a novel WLAN positioning system based on time of arrival measurements." Proc. IEEE WPNC, 2008.

  In the conventional wireless terminal station position estimation method shown in FIG. 4, the radio wave arrival times T1 to T3 between the wireless terminal station 40 whose position is to be estimated and the plurality of wireless base stations 50-1 to 50-3 are calculated. Therefore, the wireless terminal station 40 needs to connect to the plurality of wireless base stations 50-1 to 50-3 in order, and it takes time for the connection process to be equal to the number of wireless base stations.

  The present invention can perform position estimation of a wireless terminal station at high speed by measuring the radio wave arrival time between the wireless base station and the wireless terminal station while switching the distributed antennas distributed in the wireless base station. An object of the present invention is to provide a wireless terminal station position estimation method and a wireless base station.

  A first invention comprises a wireless base station capable of transmitting and receiving by switching a plurality of distributed antennas disposed in a distributed manner, and a wireless terminal station communicating with the wireless base station, the wireless base station comprising In a position estimation method of a wireless terminal station for estimating a position, the wireless base station measures a radio wave arrival time with the wireless terminal station for each of a plurality of distributed antennas, and a plurality of dispersions measured in the first step. And a second step of estimating the position of the wireless terminal station using the radio wave arrival time for each antenna.

  In the position estimation method of the wireless terminal station according to the first invention, the first step has a function of calibrating the delay time due to the length of the cable connected for each distributed antenna.

  In the position estimation method of a wireless terminal station according to the first invention, the first step has a function of calibrating a time lag inside the wireless terminal station.

  In the position estimation method of a wireless terminal station according to the first invention, the first step has a function of calibrating a radio wave arrival time deviation due to interference from another wireless station.

  In the position estimation method of a wireless terminal station according to the first invention, the first step is a transmission power of a measurement signal for measuring a radio wave arrival time transmitted by the wireless base station, or a modulation method / coding rate, or a frequency. By changing the transmission band, it has a function to reduce the radio wave arrival time deviation due to radio wave reflection.

  A wireless base station according to a second aspect of the present invention is a measurement signal for transmitting a measurement signal for measuring a radio arrival time with a plurality of distributed antennas distributed via a cable having a predetermined length and a wireless terminal station. A transmitter, a response signal receiver that receives a response signal transmitted from a wireless terminal station that has received a measurement signal, a plurality of distributed antennas are switched, and the switched distributed antenna, measurement signal transmitter, and response signal receiver are selected. For each distributed antenna, a reciprocation delay time measurement unit for measuring the round trip delay time from transmission of the measurement signal to reception of the response signal, and for each distributed antenna, the radio wave arrival time to the radio wave arrival time A radio wave arrival time calculation unit to be calculated, and a position estimation unit that estimates the position of the wireless terminal station from the radio wave arrival time for each distributed antenna.

  In the wireless terminal station according to the second aspect of the invention, there is provided means for changing the transmission power of the measurement signal, or the modulation scheme / coding rate, or the frequency / transmission band for each distributed antenna to reduce the radio arrival time deviation due to radio reflection. Prepare.

  The present invention can measure a radio wave arrival time from a measurement signal and a response signal transmitted / received between a radio base station and a radio terminal station while switching a plurality of distributed antennas distributed and arranged at high speed. The position can be estimated.

It is a figure explaining the position estimation method of the radio | wireless terminal station in this invention. It is a figure which shows the structural example of the wireless base station 10 and the wireless terminal station 20 in this invention. It is a figure explaining the propagation path of a measurement signal and a response signal. It is a figure explaining the position estimation method of the conventional radio | wireless terminal station.

FIG. 1 shows a position estimation method of a wireless terminal station in the present invention.
In FIG. 1, distributed antennas 11-1 to 11-3 distributed and arranged are connected to the radio base station 10. Here, although the example of three distributed antennas is shown, three or more distributed antennas may be used. The wireless base station 10 and each of the distributed antennas 11-1 to 11-3 are connected via cables 12-1 to 12-3 having a predetermined length, and the positions of the distributed antennas 11-1 to 11-3 are Let (x ₁ , y ₁ ), (x ₂ , y ₂ ), and (x ₃ , y ₃ ).

  The wireless base station 10 performs connection processing with the wireless terminal station 20 via the distributed antennas 11-1 to 11-3, and starts collecting location information of the wireless terminal station 20 (S1).

The wireless base station 10 first switches to the distributed antenna 11-1, transmits a measurement signal to the wireless terminal station 20, and receives a measurement signal. The wireless terminal station 20 transmits a response signal to the wireless base station 10. To do (S2). Here, the radio base station 10 measures the transmission start time of the measurement signal and the reception start time of the response signal, and acquires the round trip delay time Tm1. Since the round trip delay time Tm1 includes the delay time 2Tc1 generated in the round trip of the cable 12-1 to be connected and the signal length Ts of the measurement signal, the distributed antenna 11-1 of the wireless base station 10 and the wireless terminal The radio wave arrival time T1 with the station 20 can be obtained by the following equation.
T1 = (Tm1-2Tc1-Ts) / 2 (1)

Next, the wireless base station 10 sequentially switches to the distributed antennas 11-2 and 11-3, transmits a measurement signal to the wireless terminal station 20, and the wireless terminal station 20 that has received the measurement signal transmits to the wireless base station 10. Then, the response signal is transmitted (S3, S4), and the round trip delay times Tm2, Tm3 are measured. Here, the radio wave arrival times T2 and T3 between the distributed antennas 11-2 and 11-3 and the wireless terminal station 20 are measured with the delay times 2Tc2 and 2Tc3 generated in the round trips of the cables 12-2 and 12-3, respectively. The signal length Ts of the signal can be obtained by the following equation.
T2 = (Tm2-2Tc2-Ts) / 2 (2)
T3 = (Tm3-2Tc3-Ts) / 2 (3)

Next, in the radio base station 10, between the radio base station 10 and each of the distributed antennas 11-1 to 11-3, the radio wave arrival times T1 to T3 for each of the distributed antennas 11-1 to 11-3 are obtained. The distance R1 to R3 are converted, and the position (x, y) of the wireless terminal station 20 is estimated using the following equation (S5).
R1 = {(x−x ₁ ) ² + (y−y ₁ ) ² } ^1/2 + cΔt (4-1)
R2 = {(x−x ₂ ) ² + (y−y ₂ ) ² } ^1/2 + cΔt (4-2)
R3 = {(x-x ₃ ) ² + (y-y ₃ ) ² } ^1/2 + c Δt (4-3)

  Here, c is the speed of light, and Δt is the delay time until the wireless terminal station 20 receives a measurement signal and transmits a response signal. The delay time .DELTA.t may be adjusted by the radio wave arrival times T1 to T3 of the equations (1) to (3). There are various methods for calculating the position (x, y) of the wireless terminal station 20 from the equations (4-1) to (4-3). For example, the (x, y) is calculated by using the Newton method. be able to. In this example, the position in two dimensions is assumed, but the position of the wireless terminal station 20 can be estimated also in three dimensions by increasing the number of distributed antennas.

  FIG. 2 shows a configuration example of the wireless base station 10 and the wireless terminal station 20 in the present invention. In the drawing, only the main functional blocks related to the present invention are extracted and shown, and the functional blocks generally used also in the wireless base station and the wireless terminal station and the description thereof are omitted.

  In FIG. 2, the radio base station 10 includes distributed antennas 11-1 to 11-n (n is an integer of 3 or more), cables 12-1 to 12-n, an antenna switching unit 13, a measurement signal transmission unit 14, and a response signal. The reception unit 15, the round trip delay time measurement unit 16, the radio wave arrival time calculation unit 17, and the position estimation unit 18.

  Distributed antennas 11-1 to 11-n transmit measurement signals input from antenna switching unit 13 via cables 12-1 to 12-n to the air, and response signals received from the air are transmitted to cables 12-1 to 12 Output to the antenna switching unit 13 via −n.

  When a measurement signal is input from the measurement signal transmission unit 14, the antenna switching unit 13 switches to one of the designated distributed antennas 11-1 to 11-n and outputs the signal. Further, it outputs a response signal received by the designated distributed antenna to the response signal receiving unit 15.

  The measurement signal transmission unit 14 generates a measurement signal for measuring the round trip delay time between the wireless base station 10 and the wireless terminal station 20, and outputs the measurement signal to the antenna switching unit 13. Further, the transmission start time of the measurement signal is output to the round trip delay time measurement unit 16.

  When the wireless terminal station 20 receives the measurement signal transmitted from the distributed antenna and the response signal to the measurement signal is transmitted, the response signal reception unit 15 receives the response signal, and the reception start time is delayed by the round trip delay It is output to the time measurement unit 16.

  The round trip delay time measurement unit 16 calculates the difference between the transmission start time input from the measurement signal transmission unit 14 and the reception start time input from the response signal reception unit 15, and calculates the radio wave arrival time as the round trip delay times Tm1 to Tmn. Output to the unit 17.

  The radio wave arrival time calculation unit 17 calibrates various time deviations represented by, for example, the equations (1) to (3) from the round trip delay times Tm1 to Tmn input from the round trip delay time measurement unit 16, and the distributed antenna 11- The radio wave arrival times T1 to Tn between 1 to 11-n and the radio terminal station 20 are output to the position estimation unit 18.

  The position estimation unit 18 uses the radio wave arrival times T1 to Tn for each of the distributed antennas input from the radio wave arrival time calculation unit 17 to, for example, use the equations (4-1) to (4-3) Estimate the position.

The wireless terminal station 20 includes an antenna 21, a measurement signal receiving unit 22, and a response signal transmitting unit 23.
The antenna 21 outputs the received measurement signal to the measurement signal reception unit 22 and transmits the response signal input from the response signal transmission unit 23 to the air.

The measurement signal receiver 22 receives the measurement signal input from the antenna 21, and outputs the information to the response signal transmitter 23.
The response signal transmission unit 23 generates a response signal to the radio base station 10 in response to the measurement signal input from the measurement signal reception unit 22, and outputs the response signal to the antenna 21.

  By the way, in the radio wave arrival times T1 to T3 calculated for each of the distributed antennas 11-1 to 11-3 represented by the equations (1) to (3), there may be a deviation due to interference signals from other radio stations. There is sex. For example, when the wireless terminal station 20 transmits a response signal, transmission standby may occur due to interference from other wireless stations, and the transmission may be delayed. As described above, since there is a case where the response signal can not be normally transmitted and received due to the interference signal, when an abnormal value is detected in the radio wave arrival time, the influence of the interference is eliminated by deleting the value.

  Also, in order to calculate the radio wave arrival times T1 to T3 with high accuracy, it is effective to change the transmission format of the measurement signal for each of the distributed antennas 11-1 to 11-3. A specific example thereof will be described with reference to FIG.

  FIG. 3 shows only one distributed antenna 11 connected to the wireless base station 10, and shows an example of measuring the round trip delay time between the distributed antenna 11 and the wireless terminal station 20 without changing the transmission format. However, the propagation path in the present environment includes four types of direct components, the first reflection component by the reflector 30-1, the second reflection component by the reflector 30-2, and the third reflection component by the reflector 30-3. The delay time is calculated from four types of composite waves. The round trip time tends to increase the measurement error as the reflection component is present.

  Here, when the transmission power of the measurement signal transmitted from the wireless base station 10 is reduced, for example, the reflected wave of the measurement signal becomes smaller at the reflector 30-2 far from the wireless base station 10, and this reflection component can be reduced. .

  Further, by changing the modulation scheme and the coding rate of the measurement signal transmitted from the wireless base station 10, the necessary reception sensitivity in the wireless terminal station 20 can be changed, and some or all of the three types of reflection components can be changed. You can select whether to receive or not.

  Also, there is a method of adjusting the transmission band or transmission frequency of the measurement signal transmitted from the wireless base station 10. It is generally known that propagation paths differ depending on the transmission frequency and the transmission band. Therefore, it is possible to measure the round trip delay time of different propagation paths depending on a plurality of frequencies and transmission bands.

  In this way, by changing the transmission power, modulation scheme, coding rate, frequency and transmission band, the reflection environment of the propagation path is changed, so the round-trip delay times are averaged (including weighted averaging). By doing this, the radio wave arrival time can be calculated with high accuracy.

10, 50 Wireless base station 11 Distributed antenna 12 Cable 13 Antenna switching unit 14 Measured signal transmission unit 15 Response signal reception unit 16 Round trip time measurement unit 17 Radio wave arrival time calculation unit 18 Position estimation unit 20, 40 Wireless terminal station 21 Antenna 22 Measurement signal receiver 23 Response signal transmitter 30 Reflected object

Claims (7)

A wireless terminal comprising: a wireless base station capable of transmitting and receiving by switching a plurality of distributed antennas disposed in a distributed manner; and a wireless terminal station communicating with the wireless base station, wherein the wireless base station estimates the position of the wireless terminal station In the station position estimation method,
A first step of the radio base station measuring a radio wave arrival time with the radio terminal station for each of the plurality of distributed antennas;
A second step of estimating the position of the wireless terminal station using the radio wave arrival time of each of the plurality of distributed antennas measured in the first step. In the wireless terminal station position estimation method according to claim 1,
A position estimation method of a wireless terminal station, wherein the first step has a function of calibrating a delay time according to a length of a cable connected to each of the distributed antennas. In the wireless terminal station position estimation method according to claim 1,
The position estimation method of a wireless terminal station, wherein the first step has a function of calibrating a time lag inside the wireless terminal station. In the wireless terminal station position estimation method according to claim 1,
A position estimation method of a wireless terminal station, wherein the first step has a function of calibrating a radio wave arrival time deviation due to interference from another wireless station. In the wireless terminal station position estimation method according to claim 1,
The first step comprises changing the transmission power of the measurement signal for measuring the radio wave arrival time transmitted by the radio base station, or the modulation method / coding rate, or the radio wave by radio wave reflection by changing the frequency / transmission band. A position estimation method of a wireless terminal station having a function to reduce arrival time deviation. A plurality of distributed antennas distributed via cables having a predetermined length;
A measurement signal transmission unit that transmits a measurement signal for measuring a radio wave arrival time with a wireless terminal station; a response signal reception unit that receives a response signal transmitted from the wireless terminal station that has received the measurement signal;
An antenna switching unit that switches the plurality of distributed antennas and connects the switched distributed antenna to the measurement signal transmission unit and the response signal reception unit;
A round trip delay time measurement unit configured to measure a round trip delay time from transmission of the measurement signal to reception of the response signal for each of the distributed antennas;
A radio wave arrival time calculation unit that calculates a radio wave arrival time from the round trip delay time for each of the dispersed antennas;
A position estimation unit configured to estimate a position of the wireless terminal station from the radio wave arrival time for each of the distributed antennas. In the wireless terminal station according to claim 6,
It is characterized in that it comprises means for changing the transmission power of the measurement signal, or the modulation method / coding rate, or the frequency / transmission band for each of the distributed antennas, and reducing the radio wave arrival time deviation due to radio wave reflection. Wireless terminal station.

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