Wireless positioning means, wireless positioning apparatus and mobile position control center apparatus

• US 7,013,147 B1
• Filed: 07/17/2000
• Issued: 03/14/2006
• Est. Priority Date: 12/10/1999
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kuwahara, Mikio, Doi, Nobukazu
• Primary Examiner(s): Feild, Joseph
• Assistant Examiner(s): DESIR, PIERRE LOUIS
• Application Number:
  US09/616,314
• Time in Patent Office: 2,066 Days
• Field of Search: 455/456, 455/500, 455/501, 455/515, 455/570, 455/63, 455/67.1, 455/67.3, 455/67.6, 455/68, 4554561-4566, 455/457, 455/296
• US Class Current: 455/456.1
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

The invention intends to solve a problem that an S/I ratio of a signal from a target base station deteriorates when there is a terminal near another base station. For this purpose, a signal replica of the signal from the nearby base station is generated and the replica is subtracted from a receiving signal. A signal of the target base station is detected from the resultant receiving signal. The signal from the nearby base station is deleted from the denominator of the S/I ratio, thereby increasing the S/I ratio.

Claims

1. A wireless positioning method for estimating a position of a terminal by using reception timings of signals transmitted from at least first and second base stations in a cellular communication system, comprising:

a first step of storing received signals from a plurality of base stations in a storing circuit;

a second step of reading out received signals stored in the storing circuit and measuring a reception timing of a received signal from the first base station having a power higher than that of a received signal from a second base station;

a third step of canceling the received signal from the first base station from stored received signals;

a fourth step of reading out received signals stored in the storing circuit and measuring a reception timing of the received signal from the second base station after the second step, wherein the third step comprises;

a fifth step of forming a replica of the received signal of the first base station from the stored signals;

a sixth step of subtracting the replica from the stored signals and overwriting the signals stored in the storing circuit with a result of the subtraction step; and

a seventh step of forming the replica by processing a component of the received signal from the first base station in a procedure of despreading, demodulation and respreading by using the code division multiple access (CDMA) system.

2. A wireless positioning method according to claim 1, wherein the seventh step includes an eighth step of amplifying a received signal after the despreading, demodulation and respreading.

3. A wireless positioning method according to claim 2, wherein the eighth step includes a ninth step of correcting at least one of amplitude fluctuation and phase rotation by a signal propagation path from the first base station.

4. A wireless positioning apparatus comprising:

a signal processor for canceling a received signal from a first base station whose reception power is higher than that of a received signal from a second base station in a cellular communication system;

a CPU for processing an output signal of the signal processor;

a storing circuit for storing the received signals from the first and second base stations, and

a timing measurement circuit for measuring reception timings of the signals received from the first and second base stations based on signals stored in the storing circuit,

wherein the signal processor has;

a replica signal generating circuit for generating a replica of the received signal of the first base station from the signals stored in the storing circuit; and

a subtraction circuit for subtracting the replica from the stored signals,

wherein the stored signals are overwritten with a result of the subtraction and the timing measurement circuit measures the reception timing of the signal received from the second base station based on the overwritten signals in the storing circuit, and

wherein the replica signal generating circuit has;

a despreading circuit for despreading a component of a received signal from the first base station by using a code division multiple access system (CDMA);

a demodulating circuit for demodulating an output signal of the despreading circuit; and

a respreading circuit for respreading an output signal of the demodulating circuit.

5. A wireless positioning apparatus according to claim 4, further comprising an amplifying circuit for amplifying an output signal of the respreading circuit.

6. A wireless positioning apparatus according to claim 5, further comprising a correcting circuit for correcting at least one of amplitude fluctuation and phase rotation by a signal propagation path from the first base station.