KR100834616B1 - Method for determining ms location without gps in mobile communication system - Google Patents

Abstract

A terminal of a mobile communication system having a distance prediction system having a measurement table for storing the results of measuring the received signal power at the location and the measurement points including the base station and the distance and coordinates for each sector of the base station The location determination method may include determining identification information, round trip delay (RTD) information, and pilot phase of a base station communicating with a terminal, and determining a range in which the terminal exists by checking base station coordinates and sector azimuth angles of the identified base station. Determining the distance between the terminal and the base station using the identified base station and the RTD information between the terminal, searching for a pseudo point where the terminal is located using the determined range and distance information, and Correcting the RTD and the pilot phase by using the propagation delay error, and correcting the RTD and the pilot phase. A correction through a measurement table made by the process of determining the position of the terminal.

Terminal Positioning, Measurement Table, RTD, Pilot Phase

Description

Positioning method of mobile terminal {METHOD FOR DETERMINING MS LOCATION WITHOUT GPS IN MOBILE COMMUNICATION SYSTEM}             

1 is a view for explaining a method of determining the position of a terminal in a conventional mobile communication system;

2 is a diagram illustrating the strength characteristics of a received signal according to a distance in an LOS environment.

3 is a view for explaining a method for determining a position by correcting a propagation delay error according to an embodiment of the present invention in a mobile communication system.

4 is a diagram illustrating a configuration of an apparatus for determining a position of a terminal by the method of FIG. 3.

5 is a flowchart illustrating a process of determining a location of a terminal according to an embodiment of the present invention.

The present invention relates to a method for determining a terminal location of a mobile communication system, and more particularly, to a method for determining a location of a terminal without using a GPS.

In general, a mobile telecomunication system is called a cellular communication system because it uses a cellular method. In addition, the mobile communication system operates in various forms according to a communication method, and currently, a code division multiple access (CDMA) method is used or a trend is switched to the CDMA method. In the following embodiments of the present invention, it is assumed that the mobile communication system is a CDMA mobile communication system using a cellular method.

In addition to the communication function, the mobile communication system has a function of determining a current location of a mobile station. That is, the base station has a function of determining a location by searching for a location in the cell area where the terminal is located. In this case, the function of determining the location of the terminal may be performed by the base station or may be determined by the terminal.

In a typical mobile communication system, a base station measures a time of arrival (TOA) between messages transmitted from various terminals, and calculates a distance between the terminal and the base station using the base station. 1 is a diagram illustrating a method of determining a location of a terminal without using GPS (Non-GPS) in a conventional mobile communication system.

Referring to FIG. 1, the position lines of the base stations BTS1-BTS3 are pl1-pl3, and the terminal ms is located in the position line pl1-pl3 region. In this case, the position lines pl1-pl3 indicate the distances of the areas where the corresponding base stations BTS1-BTS3 can communicate with the terminal MS. Accordingly, the terminal MS transmits a predetermined message to at least three neighboring base stations BTS1-BTS3, and the neighboring base station BTS1-BTS3 measures the arrival time TOA of the message transmitted from the terminal MS and delivers it to a distance prediction system (not shown). do. Then, the distance prediction system predicts the position of the terminal MS by applying the location of neighboring base stations BTS1-BTS3 communicating with the terminal MS and the arrival times measured by communicating with the terminal MS in each base station in a trigonometry.

In addition, as a method for measuring the distance between the terminal and the base station, a time taken for the message transmitted from the base station to return from the terminal, that is, a method using a RTD (Round Trip Delay) can be used. However, in the actual radio wave propagation environment of the mobile communication system, various propagation paths exist due to reflections caused by building walls and various obstacles. Therefore, when the base station measures the RTD with the terminal, there is a problem that the delay due to the various propagation paths are included.

In addition, a method applied to a CDMA mobile communication system includes a hyperbolic curve of a time difference between the base stations by receiving a pilot strength measurement message (PSMM) of time difference of arrival (TDOA) between an active base station and a neighbor base station. Draw the position with the intersection of the two hyperbolas. However, this method using the arrival time difference also causes additional error due to multi-path. Since the error of the distance generated by the propagation path is not considered, there is a problem in that the exact position of the terminal is unknown.

Accordingly, an object of the present invention is to provide a method for determining a location of a terminal without using GPS in a code division multiple access communication system.

 Another object of the present invention is to provide a method for determining the location of a terminal using information stored in advance between pilot signal information and a measurement error by a multipath in a distance between a base station antenna and a terminal in a code division multiple access communication system. In providing.

It is still another object of the present invention to provide a method for determining the position of a terminal by storing a measurement error due to multipath in a database in advance in a code division multiple access communication system and comparing it with a propagation delay error at a pseudo point. .

In a mobile communication system according to an embodiment of the present invention for achieving the above object, a system for determining a terminal location includes measuring points including distance and coordinates of a base station and received signal power at a corresponding location for each sector of the base station. And a measurement table for storing the measured results, wherein the method for determining a terminal position of the mobile communication system includes measuring identification information, round trip delay (RTD) information, and pilot phase of a base station communicating with the terminal; Determining a range in which the terminal exists by checking a base station coordinate and a sector azimuth of the base station, determining a distance between the terminal and the base station using the RTD information between the identified base station and the terminal; Searching for a pseudo point where the terminal is located by using the determined range and distance information; And correcting the RTD and the pilot phase by using the propagation delay error at the found pseudo point, and determining the position of the terminal by correcting the corrected RTD and the pilot phase through the measurement table. Characterized in that made.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be noted that the same components in the figures represent the same numerals wherever possible.

According to an embodiment of the present invention, a pseudo position of a terminal is determined using information between a terminal and a base station in a mobile communication system, and a correction value of an RTD and a pilot phase is determined using an error value stored in a measurement table at the determined pseudo position. It provides a method for determining the exact position of the terminal by applying. To this end, in an embodiment of the present invention, the measurement error due to the multipath generated in the TOA or TDOA is stored in a database in advance, and the location of the terminal is compared with the information stored in the database and the propagation delay error at the pseudo point. It provides a way to determine.

The method proposed in the embodiment of the present invention is based on the signal loss factor analysis from the base station to the terminal. 2 is a diagram illustrating the power of a signal received according to a distance between a base station and a terminal. In FIG. 2, the y axis represents distance and the x axis represents power of a received signal. In FIG. 2, 200 represents a received signal power, 211 represents a threshold, 213 represents a received power P _LOS of the _LOS , and 215 represents a received signal of the NLOS. Power P _NLOS .

As shown in FIG. 2, the average signal loss level on a line of sight (LOS) in the mobile communication system is larger than the NLOS, and the deviation of the loss level is small. If a signal level comparable to the LOS is obtained at a specific location (x, y), then a threshold can be made to this value. The strength of the received signal with respect to the threshold is compared to determine whether or not the LOS.

In general, the average transmit / receive signal strengths P ^t and P ^r are as follows.

P ^r = LP ^t

Where L is the missing element.

L = L ^LOS + L ^dr

Where L ^LOS is the loss in LOS conditions and L ^dr is the total loss due to diffraction and reflection.

In the LOS environment, the signal strength P _LOS over distance is higher than P _NLOS as shown in FIG. 2. The deviation is not important here. Signal attenuation due to the topographic effects between the base station and the terminal is 6-40 dB or greater. The degree of signal loss depends on the size and characteristics of the reflective surface on which radio waves are reflected. In other words, on a smooth surface like a mirror, the signal strength of the LOS level is maintained, but in reality, such an environment is rare. Signal strength P _NLOS in NLOS environment is also reduced with distance as shown in FIG. But the deviation is very large. In most cases, the location is measured based on the distance from the base station to the terminal. In the least square method, the square of the error included in the distance information is calculated as a sum of weights to obtain a distance according to the minimum value.

According to an embodiment of the present invention, after determining the position range of the terminal using the reception delay RTD between the base station and the terminal and the arrival time delay difference TDOA between the base station, and using a calibrating table at the most similar pseudo position within the range. The position of the terminal is determined using the correction value obtained by predicting the propagation delay error between the terminal and the base station.

In order to determine the position of the terminal in the above manner, the embodiment of the present invention is first provided with a calibration table (calibration table). The measurement table is a table in which a distance prediction system measures signal reception strength at each measurement point located in a service area of each base station and stores it in a database in advance. Here, the measurement table can be configured for each base station, and in each sector, the distance between the base station and the terminal (distance from BTS) and coordinates (coordinates x, y or latitude longitude) are calculated to determine the position of the terminal. . Wherein the distance (distance from BTS) and the position (coodinates x, y or latitude longitued), etc. is a measurement point (calibration point). The LOS signal power P ^LOS is obtained at the measurement position. The measurement table obtained with the above elements may be configured as shown in Table 1 below. The measurement table as shown in Table 1 is a state in which the location information is measured in advance in the cell area in which the terminal is located, and is stored in advance in a specific database area of the distance prediction system.

BTS number Sector number Calibration point LOS signal power P ^LOS Distance from BTS Coordinates, x, y or latitude longitude One One d1 x1, y1 P ^{LOS 1} One d2 x2, y2 P ^{LOS 2} One d3 x3, y3 P ^{LOS 3} 2 d1 x4, y4 P ^{LOS 4} 2 d2 x5, y5 P ^{LOS 5} 2 d3 x6, y6 P ^{LOS 6}

The distance prediction system having the measurement table as described above determines the position of the terminal in the following order.

First, in the first step, base station identification information, RTD information, and PSMM are received from a message transmitted and received between the terminal and the base station, and the difference between the base station is collected.

The measuring of the RTD information in the first step includes transmitting a specific message from a base station to a terminal, calculating a response arrival time of the transmission message, measuring the RTD, and measuring a system delay time from the measured RTD. After subtracting the unidirectional propagation delay time, and calculating the unidirectional propagation delay time by converting the unidirectional propagation delay time into a distance, it consists of a process of generating this as RTD information. The process of calculating the unidirectional propagation distance is performed by calculating the speed of the chip (0.8138 μm) * the speed of light (2.988 * 10 ⁸ m / s) * unidirectional propagation delay.

In the first step of determining the pilot phase, the active and neighboring base stations receive the PSMM signals measuring the strength of the pilot signal output from the terminal, and collects the arrival time difference of the received PSMM signals The pilot phase is measured.

In the second step, a database is queried to identify the base station coordinates and sector azimuths of the identified base station, and then converted to determine the range in which the terminal exists.

The determining of the existence range of the terminal in the second step may include acquiring cell and sector information of the active base station and neighboring base stations, and using the measured RTD value in the obtained information. The distance between the base stations is determined to determine the existence range of the terminal.

In a third step, the distance between the terminal and the base station is determined using the RTD information between the identified base station and the terminal.

In the fourth step, the pseudo point is searched using the determined range and distance information.

Determining the pseudo range of the terminal in the fourth step, the error is less compared to the propagation delay for the predetermined intervals within the set existence range and the information of the pilot signal transmitted from each base station The point is determined as the pseudo range.

In the fifth step, the pilot phases of the RTD and the PSMM are corrected using the propagation delay error at the found pseudo point.

In the sixth step, the position of the terminal is determined using the values corrected through Table 1 and the measurement table.

Table 1 shows a configuration of a measuring table according to an embodiment of the present invention. The measurement table is stored in a database of a distance prediction system.

The distance prediction system determines the position of the terminal while correcting the propagation delay error as shown in FIG. 3.

Referring to FIG. 3, when BTS1-BTS3 represents a base station, pl1-pl3 is a position line of a position in the LOS of a corresponding base station, and l1-l3 are corrected position lines of the corresponding base station, respectively. (accurate line of position). First, the distance prediction system predicts the position 31 of the approximate terminal 31 by the position lines pl1-pl3 of the base stations BTS1-BTS3. Thereafter, the distance prediction system measures the RTD and the pilot phase, and then sets the existence range of the terminal using the measured RTD and the pilot phase. In addition, by comparing the propagation delays for points at predetermined intervals and the information on the pilot signals sent by the base stations within the range set as described above, the point where the least error occurs is estimated as the pseudo point 35 of the terminal. reliablity of measurements of pilot PN phase.

After predicting the pseudo point 33, the pilot phases of the RTD and the PSMM are corrected using information on the propagation delay and the pilot signal of the pseudo point using the measurement table as shown in Table 1. In addition, by repeating the above-described correction operation, the line positions 1-1 (accurate position of line) of FIG. 3 are determined, thereby determining the exact point 35 at which the terminal is located.

A method of determining a location of a terminal according to an embodiment of the present invention as described above will be described in detail with reference to FIG. 4. As shown in FIG. 4, the method of determining the location of the terminal is performed in the distance prediction system. The distance prediction system may be located in a base station controller or may be installed independently.

In step 412 of FIG. 4, the RTD and the PSMM are measured. To this end, the distance prediction system transmits a specific message to the terminal through a base station currently communicating with the terminal, and then measures a time when a response to the transmitted specific message arrives. Subtracting the system delay value from the measured arrival time delay value eliminates the delay component that occurs in the system. In addition, since the distance needs to obtain a propagation delay value for one direction, the value obtained as a result of the transmission and reception delay (forward and reverse propagation delay) must be divided in half. Therefore, the unidirectional propagation delay obtained by the measured RTD is expressed by Equation 1 below.

Unidirectional Propagation Delay = (Measured RTD-System Delay) / 2

= (Forward propagation delay + reverse propagation delay) / 2

The unidirectional propagation delay calculated in Equation 1 is calculated in units of chips. Here, the CDMA communication system has a speed of 1.2288 Mcps, so one chip is about 0.8138 µm. Therefore, in the CDMA communication system having a speed of 1.2288 Mcps, the unidirectional propagation delay is converted into Equation 2 below.

Unidirectional Propagation Distance = 0.8138μm * Light Speed (2.988 * 10 ⁸ m / s) * Unidirectional Propagation Delay

= 243.97 * Unidirectional Propagation Delay

As described above, the unidirectional propagation distance by the RTD, that is, the RTD distance can be calculated (measured).

In addition, the PSMM signal transmitted from the terminal collects the time difference of arrival of the pilot signal seen by the terminal of the active base station and neighboring base stations. In addition, the phase of the pilot signal may be measured by the arrival time difference between the collected pilot signals.

In step 414 of FIG. 4, the distance prediction system determines the existence range of a basic terminal. To this end, the distance prediction system acquires cell and sector information of the base stations adjacent to the active base station and sets the basic range in which the terminal is located. Thereafter, the distance prediction system obtains the distance between each terminal and the base stations using the RTD and pilot phase values measured in step 412 in step 416, and the current terminal exists as shown in FIG. 1 by the distance between the base stations and the terminal. It will determine the range.

The distance prediction system finds a pseudo point (33 in FIG. 3) of the terminal in step 418. That is, the distance prediction system compares the propagation delays for points at predetermined intervals with the information on the pilot signals sent by the base stations within the range set as described above in step 418 to determine the point where the least error occurs. Decide on a doctor's point. At this time, the internal processing procedure uses the measured signal strength specific gravity V ^I from the base station. Here, the position is obtained by minimizing the specific gravity.

At this time, the algorithm proceeds in the following order.

First, the approximate position (x ⁰ , y ⁰ ) (31 in FIG. 3) is obtained by the conventional method.

Then, the SNR (Ec / Io) ⁱ and the pilot signal power P ⁱ (i = 1, N) are obtained from the measurable base station. Next, the signal strength P ^LOS is measured when the LOS is at the position (x ⁰ , y ⁰ ). This is shown in FIG.

In step 420, the distance prediction system corrects the pilot phases of the RTD and the PSMM using information on the propagation delay and the pilot signal at the pseudo point. In step 420, the distance prediction system corrects the pilot phases of the RTD and the PSMM by referring to the propagation delay and information related to the base stations at the pseudo point and the measurement table as shown in Table 1 below.

In operation 422, the distance prediction system determines the position 35 of the terminal using the corrected RTD and pilot phase values. That is, the actual position of the terminal is determined by using the corrected RTD, the pilot phase, and regional information of the pilot strength. In addition, when the RTD and pilot phases are repeatedly corrected by performing steps 424 and 426, the line L1-L3 is correctly corrected, so that the error of the position of the terminal can be further corrected to determine the correct position.

As described above, the pseudo position of the terminal is determined using the information between the terminal and the base station, and the correct position is determined by applying a correction value of the RTD and the pilot phase using the error value stored in the measurement table at the pseudo position. There is an effect that can determine the position of the terminal more accurate without special changes to the terminal or the base station.

Claims (6)

A terminal of a mobile communication system having a distance prediction system having a measurement table for storing the results of measuring the received signal power at the location and the measurement points including the base station and the distance and coordinates for each sector of the base station In the positioning method, Measuring identification information, round trip delay (RTD) information, and pilot phase of a base station communicating with the terminal; Determining a range in which the terminal exists by checking base station coordinates and sector azimuth of the identified base station; Determining a distance between the terminal and the base station by using the RTD information between the identified base station and the terminal; Searching for a pseudo point where the terminal is located using the determined range and distance information; Correcting the RTD and pilot phase by using a propagation delay error at the found pseudo point; And determining the position of the terminal by correcting the corrected RTD and pilot phase through the measurement table. The method of claim 1, wherein the measuring of the RTD information comprises: Transmitting a specific message from a base station to a terminal, calculating a response arrival time of the transmission message, and measuring the RTD; Calculating a unidirectional propagation delay time after subtracting a system delay time from the measured RTD; And calculating a one-way propagation distance by converting the one-way propagation delay time into a distance and generating the same as RTD information. The terminal of claim 2, wherein the calculating of the unidirectional propagation distance is performed by calculating a chip speed (0.8138 μm) * light speed (2.988 * 10 ⁸ m / s) * unidirectional propagation delay. Positioning method. The method of claim 1, wherein the determining of the pilot phase, Active and neighboring base stations receive the PSMM signals measuring the strength of the pilot signal output from the terminal, and collects the time difference of arrival of the received PSMM signals terminal measurement method characterized in that the pilot phase. The method of claim 1, wherein the determining of the existence range of the terminal comprises: Acquiring cell and sector information of the active base station and neighboring base stations; And determining the existence range of the terminal by obtaining a distance between the terminal and the base stations using the measured RTD value in the obtained information. The method of claim 1, wherein the determining the pseudo range of the terminal comprises: The position of the terminal, characterized in that the point where the error is small by comparing the propagation delay for the predetermined intervals within the set existence range and the information of the pilot signal transmitted from each base station to determine the pseudo range How to decide.

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