JP2002010325A - Position estimation method in wireless communication system - Google Patents

Abstract

(57) [Problem] To provide a position estimating method in a wireless communication system capable of estimating the position of a mobile device with high accuracy without being affected by the installation form of a base station. SOLUTION: A signal from each base station is received by a mobile station, a reception strength of each base station is measured, and a reception strength of each base station is paired with a base station identification code and transmitted to a position estimating apparatus. (S
10) Read out the transmission power and installation position information corresponding to the base station identification code (S12), and normalize the reception strength of each base station according to the transmission power corresponding to the base station identification code and the reference transmission power. (S14) The above problem is solved by estimating the position of the mobile device in accordance with the normalized reception intensity and the installation position information (S16).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a position estimation method in a wireless communication system, and more particularly to a position estimation method in a wireless communication system for estimating the position of a mobile station from reception strength.

[0002]

2. Description of the Related Art For example, as a method of estimating the position of a mobile station included in a radio communication system, the reception intensity (reception level) of a downlink signal transmitted from a plurality of base stations is measured in the mobile station, and the measured level is measured. There is a method of estimating the position of a mobile device according to the reception strength of each base station.

In this method of estimating the position of a mobile device, the position of the mobile device is estimated by the following procedure. First, the mobile station measures the reception strength of downlink signals transmitted from a plurality of base stations for each base station for a predetermined time (for example, several seconds).
The mobile device calculates an average value of the reception intensity of each base station measured at a predetermined time, and sets the calculated average value of the reception intensity as a measured reception intensity from each base station. Then, the mobile device transmits the measured reception intensity of each base station to the position estimating device. The position estimating apparatus calculates the subdivided point of the received intensity as the estimated position of the mobile device using the received measured reception intensity of each base station and the installation position information of each base station.

[0004] Specifically, the installation position of the i-th base station is (xi, yi), and the reception strength from the i-th base station is Ei.
In this case, the estimated position (X, Y) of the mobile device is calculated using the following equation (1).

[0005]

(Equation 1) In equation (1), n is the total number of base stations for which downlink signals are used for estimating the position of the mobile station. As a result of the calculation using Expression (1), a point at which the center of gravity of each base station is weighted with the measured reception intensity has been calculated as the estimated position of the mobile station.

[0006]

The base stations in a wireless communication system are not always the same in terms of their transmission power and antenna installation height. Even if the geographical distance between the mobile station and the base station is equal, the measured reception strength changes according to the installation form such as the transmission power of the base station and the antenna installation height.

Generally, the higher the transmission power of the base station, the higher the measured reception intensity. Also, the higher the antenna installation height of the base station, the higher the measured reception intensity. Therefore, even when the measured reception intensities of the respective base stations measured by the mobile device are all equal, the geographical distances between the mobile device and the respective base stations are not necessarily all equal.

[0008] However, the conventional position estimation method is based on the premise that only the magnitude of the measured reception strength from each base station corresponds to the length of the geographical distance between the mobile station and each base station. Therefore, when the installation forms of the plurality of base stations used for position estimation are not the same, the conventional position estimation method has a problem in that the accuracy of the estimated position of the mobile device deteriorates.

The present invention has been made in view of the above points, and provides a position estimating method in a wireless communication system capable of estimating the position of a mobile station with high accuracy without being affected by the installation form of a base station. The purpose is to provide.

[0010]

SUMMARY OF THE INVENTION To solve the above-mentioned problems, the present invention provides a radio communication system comprising a mobile station, a base station, and a position estimating apparatus. Utilizing a system, in the position estimation method for estimating the position of the mobile station, a signal from each base station is received by the mobile station, and the reception strength of each base station is measured. The power is transmitted to the position estimating apparatus in combination with the base station identification code, the transmission power and the installation position information corresponding to the base station identification code are read, and the reception strength of each base station is determined by the base station identification code. And normalizing according to the transmission power and the reference transmission power, and performing the position estimation of the mobile device according to the normalized reception intensity and the installation position information.

In such a position estimating method, the reception intensity of each base station measured by the mobile station is normalized according to the transmission power and the reference transmission power, and the mobile station is moved according to the normalized reception intensity and the installation position information. Estimate aircraft position. As described above, it is possible to remove the variation in the reception intensity due to the difference in the transmission power of the base station, and it is possible to estimate the position of the mobile device with high accuracy.

According to another aspect of the present invention, there is provided a wireless communication system including a mobile station, a base station, and a position estimating apparatus. In the position estimating method for estimating the position of a mobile station, a signal from each base station is received by the mobile station, and the reception strength of each base station is measured. And sent to the position estimation device as a set,
The antenna installation height and the installation position information corresponding to the base station identification code are read, and the reception strength of each of the base stations is
A new reception strength is calculated by multiplying a weight coefficient calculated from the antenna installation height and the reference antenna installation height corresponding to the base station identification code, and the movement is performed according to the calculated new reception strength and the installation position information. It is characterized in that the position of the aircraft is estimated.

In such a position estimation method, a new reception intensity is calculated by multiplying the reception intensity of each base station measured by the mobile station by a weight coefficient calculated from the antenna installation height and the reference antenna installation height. . Then, the position of the mobile device is estimated in accordance with the calculated new reception strength and installation position information. As described above, it is possible to remove the variation in the reception intensity due to the difference in the antenna installation height of the base station, and it is possible to estimate the position of the mobile device with high accuracy.

Reception strength depending on antenna height of base station
Reception received by the mobile device to remove the degree of variation
From the viewpoint of calculating the weight coefficient to be applied to the intensity,
The method for estimating the position is described in claim 3.
, The antenna installation height and the reference antenna installation height
The weighting factor calculated from is: ki = (H0 / Hi)^α  ki: weight coefficient, Hi: antenna installation of the i-th base station
Height, H0: reference antenna installation height, α: multiplier.

According to such a position estimating method, the variation of the reception strength depending on the antenna installation height of the base station is removed by using the antenna installation height Hi of the base station, the reference antenna installation height H0, and the multiplier α. Is easily calculated.

According to another aspect of the present invention, there is provided a wireless communication system including a mobile station, a base station, and a position estimating apparatus. In the position estimating method for estimating the position of the mobile device, a first position estimation signal to which a mobile device identification code and an order code indicating the order of the position estimation operation are added is transmitted from the mobile device, and Is received by a plurality of base stations, and the reception strength of each base station is measured.
A mobile station identification of a mobile station for performing position estimation by transmitting a second position estimation signal in which the reception strength of each base station is combined with a base station identification code and the first position estimation signal to the position estimation device. The second position estimation signal is selected according to a code and a sequence code, the installation position information is read out according to the base station identification code included in the selected second position estimation signal, and included in the second position estimation signal. It is characterized in that the position of the mobile device is estimated according to the installation position information read out according to the reception strength and the base station identification code.

In such a position estimation method, the reception strength of a signal transmitted from a mobile device is measured by an unspecified number of base stations installed around the mobile device. The measured reception intensity is transmitted to the position estimating device as a second position estimating signal associated with the base station identification code and the first position estimating signal. The second position estimation signal transmitted to the position estimation device is selected based on the mobile device identification code and the order code.

[0018] Then, the mobile station according to the reception strength included in the selected second position estimation signal and the installation position information corresponding to the base station identification code included in the selected second position estimation signal are determined. Perform position estimation. As described above, by using the signal transmitted from the mobile device to each base station, it is possible to estimate the position of the mobile device with high accuracy regardless of the transmission power of each base station.

[0019]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration diagram of a wireless communication system 1 to which a position estimation method according to an embodiment of the present invention is applied. The wireless communication system 1 of FIG. 1 is configured to include a mobile device 10, base stations 11 to 13, a position estimating device 15, and a wired network 14 that connects the base stations 11 to 13 and the position estimating device 15 by wires. .

The mobile device 10 is, for example, a mobile phone, a car phone, or a PHS (Personal Handy phon).
e System) and other PS (Portable S)
station), which is a mobile station among the radio stations configuring the radio communication system 1. Also, the base stations 11 to 1
Reference numeral 3 denotes a CS (Cell Stat) constituting the wireless communication system 1 such as a mobile phone, a car phone, and a PHS.
ion). In FIG. 1, base stations 11 to 13 are assumed to be installed at positions where signals transmitted from mobile device 10 can be received. The position estimating device 15 is supplied with information for estimating the position of the mobile device 10 from the mobile device 10 or the base stations 11 to 13, and estimates the position of the mobile device 10 according to a procedure described later.

Here, the outline of the procedure of the position estimation method of the present invention will be described with reference to the wireless communication system 1 of FIG. When estimating the position of the mobile device 10, the mobile device 1
The signal reception strength is measured between the base station 11 and the base stations 11 to 13. The measured reception strength is supplied to the position estimation device 15 in association with the base station identification code assigned to each base station.

The position estimating device 15 performs an operation related to position estimation, and thus information on the installation positions (for example, latitude and longitude) of each of the base stations 11 to 13, antenna installation height, reference antenna installation height, transmission power, reference transmission power, and the like. Or a configuration in which information can be obtained from such a database. In addition,
Although the wireless communication system 1 of FIG. 1 shows an example in which the position estimation device 15 is connected to the wired network 14, a configuration in which the function of the position estimation device 15 is provided in a wired network, a base station, or a mobile device. Is also conceivable.

The details of the position estimation method of the present invention will be described below with reference to the flowcharts of FIGS. FIG. 2 shows a flowchart of the first embodiment of the position estimation method of the present invention.

When estimating the position of the mobile station 10, the mobile station 10 measures the reception intensity Ei (for example, i = 1 to 3 in FIG. 1) of the signal transmitted from the base stations 11 to 13 for each base station. I do. The reception strength of a signal transmitted from the base station 11 is E1, the reception strength of a signal transmitted from the base station 12 is E2, and the reception strength of a signal transmitted from the base station 13 is E.
3 is assumed. The mobile device 10 transmits information {CS-IDi, Ei} in which the measured reception strength Ei is associated with the base station identification code CS-IDi of the i-th base station to the position estimation device 15. For example, the reception strength E1 of the signal transmitted from the base station 11 is transmitted to the position estimation device 15 as information {CS-ID1, E1} associated with the base station identification code CS-ID1 of the base station 11.

In FIG. 2, in step S10, when position estimating device 15 receives information {CS-IDi, Ei} from mobile device 10, the process proceeds to step S12. In step S12, the position estimating device 15 obtains the installation position information {xi, yi} and the transmission power Si of the base stations 11 to 13 corresponding to the CS-IDi included in the information {CS-IDi, Ei} from, for example, the aforementioned database. read out.

In step S14 following step S12, the position estimating device 15 normalizes the reception intensity Ei using the transmission power Si and a preset reference transmission power S0 (for example, 20 mW). Specifically, the measured reception intensity ri obtained by normalizing the reception intensity Ei is calculated by using the following equation (2).

Ri = Ei (S0 / Si) (2) Following step S14, the process proceeds to step S16, where the position estimating device 15 uses the normalized measured reception intensity ri to determine the position of the mobile device 10. Make an estimate. Specifically, the estimated position {X, Y} of the mobile device 10 is calculated using the following equation (3).

[0029]

(Equation 2) Here, n is the total number of base stations for which downlink signals are used for estimating the position of the mobile station. In the example of FIG. 1, n = 3. Also, the reference transmission power S0 used in equation (2) may be arbitrarily selected from the transmission power of the base station used for position estimation without being set in advance.

As described above, the reception intensity Ei of each base station measured by the mobile station 10 is normalized according to the transmission power Si and the reference transmission power S0, and the normalized measured reception intensity ri and the installation position information ｛xi , Yi}, it is possible to remove the variation of the reception strength Ei due to the difference in the transmission power Si of the base stations 11 to 13 and to accurately determine the position of the mobile device 10. It can be estimated.

FIG. 3 is a flowchart of a second embodiment of the position estimating method according to the present invention. When estimating the position of the mobile device 10, as in the flowchart of FIG.
Is the reception strength Ei of the signal transmitted from the base stations 11 to 13
Is measured for each base station. The mobile station 10 determines the measured reception strength Ei and the base station identification code CS-IDi of the i-th base station.
Is transmitted to the position estimation device 15. In FIG. 3, in step S10, the position estimating device 15 receives information {CS-IDi,
When Ei｝ is received, the process proceeds to step S18. In step S18, the position estimating device 15 transmits the information {CS-IDi,
Base stations 11 to 11 corresponding to CS-IDi included in Ei #
Thirteen installation position information {xi, yi} and antenna installation height Hi are read, for example, from the database described above.

After step S18, the process proceeds to step S20, where the position estimating device 15 determines the antenna installation height Hi and a preset reference antenna installation height H0 (for example,
3.5m) is used to calculate the weight coefficient ki. Specifically, the weight coefficient ki is calculated by using the following equation (4).

Ki = (H0 / Hi) ^α (4) where α is a preset multiplier (for example, 0.29
5). Then, the measured reception intensity si is calculated by calculating the product of the calculated weight coefficient ki and the reception intensity Ei by using Expression (5).

Si = Ei · ki (5) Following step S20, the process proceeds to step S22, where the position estimating device 15 estimates the position of the mobile device 10 using the calculated measured reception strength si. Specifically, the estimated position {X, Y} of the mobile device 10 is calculated using the following equation (6). Note that n is the total number of base stations for which downlink signals are used for estimating the position of the mobile device 10. In the example of FIG.
n = 3.

[0035]

(Equation 3) In this way, a new measured reception strength si is calculated by multiplying the reception strength Ei of each base station measured by the mobile device 10 by the weight coefficient ki calculated from the antenna installation height Hi and the reference antenna installation height H0. , The calculated new measured reception intensity s
i and the mobile station 1 according to the installation location information {xi, yi}.
By performing the position estimation of 0, it is possible to remove the variation of the reception strength Ei due to the difference in the antenna installation height Hi of the base stations 11 to 13, and it is possible to estimate the position of the mobile device 10 with high accuracy. .

FIG. 4 shows a flowchart of the base stations 11 to 13 according to the third embodiment of the position estimating method of the present invention. The mobile device 10 has a unique mobile device identification code PS-ID set corresponding to the mobile device 10. When estimating the position of the mobile device 10, the mobile device 10 generates a first position estimation signal {PS-ID, m} including a unique mobile device identification code PS-ID and an order code m indicating the order of the position estimation operation.
Is transmitted to an unspecified number of base stations installed around the mobile device 10.

In FIG. 4, in step S22, the base station 11
To 13 are first position estimation signals $ PS-I from the mobile device 10.
When D, m} is received, the process proceeds to step S24. In step S24, the base stations 11 to 13 measure the reception intensity Pi of the received first position estimation signal, and store the reception intensity Pi.

In step S26 following step S24, the base stations 11 to 13 transmit the received first position estimation signal {PS-ID, m}, the reception strength Pi, and the base station identification code CS-IDi. Second position estimation signal {CS-
IDi, Pi, PS-ID, m} are created. And
Proceeding to step S28 following step S26, the base stations 11 to 13 generate the second position estimation signal {CS-ID}.
i, Pi, PS-ID, m} are transmitted to the position estimation device 15. For example, the second position estimation signal ΔC from the base station 11
S-ID1, P1, PS-ID, m｝ are position estimation devices 1
5 will be sent.

FIG. 5 shows a flowchart of the position estimating device 15 according to the third embodiment of the position estimating method of the present invention. In FIG. 5, in step S30, position estimating device 15 transmits second position estimating signal {CS-IDi, P} from base stations 11 to 13.
When i, PS-ID, m} is received, the process proceeds to step S32. In step S32, the position estimating device 15 outputs the second position estimating signal {CS-IDi, P
i, PS-ID, m}, a second position estimation signal {CS-IDi, P
i, PS-ID, m}.

The predetermined time for waiting for an incoming call is determined by the base station 11.
13 can be determined in advance in accordance with the difference in processing capability of .about.13, the transmission path delay time, and the like. That is, each of the base stations 11 to 1
3 is a second position estimation signal {CS-IDi, Pi, PS-
ID, m} can be sent to the position estimation device 15 independently.

After step S32, the process proceeds to step S34.
Of the second position estimation signal {CS-IDi, Pi, PS-ID, m} including the mobile station identification code PS-ID.
The second position estimation signal {CS-ID} selected at this time
i, Pi, PS-ID, m} are transmitted from a certain mobile device 10 to an unspecified number of base stations 11 to 13.
This is created from the position estimation signal {PS-ID, m}.

After step S34, the process proceeds to step S36, where the position estimating device 15 selects the second position estimating signal {CS-IDi, Pi, PS-I selected in step S34.
D, m} according to the order code m, and the second position estimation signal {CS-IDi,
Pi, PS-ID, m} are selected. In step S36, the position estimation device 1 is significantly delayed due to some cause.
5, the second position estimation signal {CS-IDi, P
i, PS-ID, m} can be eliminated.

After step S36, the process proceeds to step S38, where the position estimating device 15 selects the second position estimating signal {CS-IDi, Pi, PS-I selected in step S36.
The position of the mobile device 10 is estimated using D, m 機. More specifically, the position estimating device 15 determines the installation position information corresponding to the base station identification code CS-IDi included in the selected second position estimation signal {CS-IDi, Pi, PS-ID, m}. xi, yi} is read out, and the estimated position {X, Y} of the mobile device 10 is calculated using the following equation (7). Note that n1 is the second position estimation signal {CS-IDi, Pi, PS-ID,
m｝.

[0044]

(Equation 4) As described above, the reception strength Pi of the signal transmitted from the mobile device 10 is measured by the unspecified number of base stations 11 to 13 installed around the mobile device 10. The measured received signal strength Pi is the second signal associated with the base station identification code CS-IDi and the first position estimation signal {PS-ID, m}.
Position estimation signal {CS-IDi, Pi, PS-ID,
It is sent to the position estimation device 15 as m｝. Second position estimation signal {CS-ID} sent to position estimation device 15
i, Pi, PS-ID, m} is the mobile station identification code PS-
Sorted by ID and order code m.

Then, the reception strength Pi included in the selected second position estimation signal {CS-IDi, Pi, PS-ID, m}, and the installation position information {xi corresponding to the base station identification code CS-IDi. , Yi}, the position of the mobile device 10 can be estimated with high accuracy regardless of the transmission power Si of each of the base stations 11 to 13.

In the present embodiment, an example has been described in which the first position estimation signal {PS-ID, m} is transmitted to an unspecified number of base stations installed around the mobile device 10. Are directed individually to the base stations installed around the mobile device 10 in the order of the first position estimation signal {PS-I
D, m} can also be transmitted. In this case, each of the base stations 11 to 13 can reliably receive the first position estimation signal.

Also, by combining the position estimating method shown in the flowchart of FIG. 2 and the position estimating method shown in the flowchart of FIG. 3, a position estimating method for correcting the measured reception intensity according to the transmission power and the antenna installation height can be realized. . Further, by combining the position estimating method shown in the flowcharts of FIGS. 4 and 5 with the position estimating method shown in the flowchart of FIG. 3, the measured reception strength from the mobile device 10 is changed according to the antenna installation height of the base stations 11 to 13. A position estimation method to be corrected can be realized.

[0048]

As described above, according to the present invention, in a position estimating method in a wireless communication system, it is possible to suppress factors affecting the receiving strength such as the transmission output of the base station and the antenna installation height, and It is possible to estimate the position of the machine with high accuracy. Further, since the signal supplied from the mobile station to the base station can be used as the measurement target of the reception strength, it is possible to estimate the position of the mobile station with high accuracy regardless of the transmission power of each base station. Become.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a wireless communication system to which a position estimation method according to an embodiment of the present invention is applied.

FIG. 2 is a flowchart of a first embodiment of the position estimation method of the present invention.

FIG. 3 is a flowchart of a position estimation method according to a second embodiment of the present invention.

FIG. 4 is a flowchart of a base station according to a third embodiment of the position estimation method of the present invention.

FIG. 5 is a flowchart of a position estimating apparatus according to a third embodiment of the position estimating method of the present invention.

[Explanation of symbols]

 Reference Signs List 1 wireless communication system 10 mobile station 11 to 13 base station 14 wired network 15 position estimation device ki weighting factor Hi antenna installation height H0 reference antenna installation height α multiplier CS-IDi base station identification code Si transmission power S0 reference transmission power Ei, Pi Received power ri, si Measured received power Hi Antenna installation height H0 Reference antenna installation height PS-ID Mobile station identification code m Order code

Claims (4)

[Claims] 1. A position estimating method for estimating the position of a mobile station using a wireless communication system including a mobile station, a base station, and a position estimating apparatus, wherein a signal from each base station is moved. The reception strength of each base station is measured and received, and the reception strength of each base station is paired with a base station identification code and sent to the position estimating apparatus, and the transmission corresponding to the base station identification code is transmitted. Reading the power and the installation location information, normalizing the reception strength of each base station according to the transmission power and the reference transmission power corresponding to the base station identification code, to the normalized reception strength and the installation location information A position estimating method for estimating the position of the mobile device in response to the request. 2. A position estimating method for estimating a position of a mobile station using a wireless communication system including a mobile station, a base station, and a position estimating apparatus, wherein a signal from each base station is moved. The reception strength of each base station is measured and received, and the reception strength of each base station is paired with a base station identification code and sent to the position estimating apparatus. The antenna corresponding to the base station identification code The installation height and the installation position information are read out, and the reception strength of each base station is multiplied by a weight coefficient calculated from the antenna installation height and the reference antenna installation height corresponding to the base station identification code to calculate a new reception strength. A position estimating method for estimating the position of the mobile device according to the calculated new reception intensity and the installation position information. 3. The position estimating method according to claim 2, wherein the position is calculated from the antenna installation height and a reference antenna installation height.
The weighting factor to be used is: ki = (H0 / Hi)^α  ki: weight coefficient, Hi: antenna installation of the i-th base station
Height, H0: Reference antenna installation height, α: Calculated using multiplier
A position estimating method characterized by issuing. 4. A position estimating method for estimating the position of a mobile station using a wireless communication system including a mobile station, a base station, and a position estimating apparatus, comprising: A first position estimation signal to which a sequence code indicating the order of the sequence is assigned is transmitted from the mobile device, and the first position estimation signal from the mobile device is received by a plurality of base stations, and each base station receives the first position estimation signal. Measuring the reception strength, transmitting a second position estimation signal in which the reception strength of each base station is combined with the base station identification code and the first position estimation signal to the position estimation device, and performing position estimation; Selecting the second position estimation signal according to the mobile device identification code and the order code of the mobile device; reading the installation position information according to the base station identification code included in the selected second position estimation signal; Included in the estimation signal A position estimating method for estimating the position of the mobile device in accordance with the installation intensity information read in accordance with the received signal strength and the base station identification code.