US 5,666,662 AGranted

Method for detecting the location of a mobile terminal

AssigneeNEC Corporation

InventorToshiyuki Shibuya

Life of this patent

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Abstract

In location detection of a mobile terminal, a location inquiry signal is transmitted from one or more base stations to the mobile terminal at predetermined intervals. In response to the location inquiry signal, the mobile terminal transmits a location signal including its identification information such as a telephone number. The location signal is received by at least three base stations neighboring to the mobile terminal. The respective distances from that base stations to the mobile terminal are calculated based on the respective field strength values of the location signal received by the base stations, and the location of the mobile terminal is detected based on the calculated distances. More specifically, the location is calculated as an intersection of the respective circles defined by radiuses of the calculated distances from the base stations receiving the location signal.

Claims8

Dependent claims

A method for detecting the location of a mobile terminal in a mobile radio communication system including a plurality of base stations and a plurality of mobile terminals, the method comprising the steps of:

emitting a location inquiry signal from at least one of the base stations through a control channel which is used to transmit the location inquiry signal;
emitting a location signal from each of the mobile terminals receiving the location inquiry signal from the at least one base station, the location signal including identification information of each of the mobile terminals;
receiving the location signal from each of the mobile terminals in at least three base stations neighboring each of the mobile terminals;
calculating the respective distances from the base stations receiving the location signal of a specified mobile terminal, based on the respective field strength values detected from the received location signal, the specified mobile terminal being identified by the identification information included in the location signal;
and
calculating the location of the specified mobile terminal among the base stations receiving the location signal of the specified mobile terminal, based on the respective distances from the base stations receiving the location signal to the specified mobile terminal.

3 more elements

emitting a location inquiry signal from at least one of the base stations at predetermined intervals through a control channel which is used to transmit the location inquiry signal;
emitting a location signal from each of the mobile terminals receiving the location inquiry signal from the at least one base station, the location signal including identification information of each of the mobile terminals;
receiving a location signal from each of the mobile terminals in at least three base stations neighboring each of the mobile terminals;
calculating the respective distances from the base stations receiving the location signal to a specified mobile terminal, based on the respective field strength values detected from the received location signal at the predetermined intervals, the specified mobile terminal being identified based on the identification information included in the location signal;
calculating the location of the specified mobile terminal among the base stations receiving the location signal of the specified mobile terminal, based on the respective distances from the base stations receiving the location signal to the specified mobile terminal at the predetermined intervals;
and
storing the locations of the specified mobile terminal at the predetermined intervals.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/278,516Filed 21 Jul 1994
Priority: JP 5-20207723 Jul 1993
Granted: 9 Sep 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H04W 64/00
Locating users or terminals or network equipment for network management purposes
G01S 5/14
Using radio waves: determining absolute distances from a plurality of spaced points of known location
G01S 11/06
Using radio waves: using intensity measurements
G01S 13/78
Wherein pulse-type signals are transmitted: discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe