Method and apparatus for locating a subscriber unit in a communication system

• US 6,141,558 A
• Filed: 05/07/1998
• Issued: 10/31/2000
• Est. Priority Date: 05/07/1998
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Chen, Brian Cheng-Jean
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): Corsaro, Nick
• Application Number:
  US09/074,285
• Time in Patent Office: 908 Days
• Field of Search: 455/440, 455/456, 455/115, 455/226.1, 455/342, 455/450, 455/457, 455/463
• US Class Current: 455/456.1
• CPC Class Codes: G01S 3/58 Rotating or oscillating beam systems using continuous analysis of received signal for determining direction in the plane of rotation or oscillation or for determining deviation from a predetermined direction in such a plane G01S3/14 takes precedence
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 76/50 for emergency connections

Abstract

After determining a distressed mobile subscriber communication unit 100 is within a communication coverage area (60) of a base transceiver station (BTS) (22), a mobile BTS (55) positioned at a first location (201) uses a rotating directional antenna (46) to force mobile subscriber communication units including the mobile subscriber communication unit (100) to hand off communication. When the mobile BTS (55) detects the subscriber ID associated with the mobile subscriber communication unit (100) during handoff, a first direction of the directional antenna (46) is noted. The same procedure is repeated at another location (202) and a second direction of the directional antenna (46) is noted. A triangulation process using the first and second direction of the directional antenna and the first and second locations (201) and (202), reveal the location (203) of the mobile subscriber communication unit (100).

Claims

1. A method for locating a subscriber in a cellular communication system, the method comprising the steps of:

a) providing;

a plurality of stationary base stations each having a station ID;

at least one mobile base station coupled to the plurality of stationary base stations, the at least one mobile base station having a rotatably mounted directional antenna; and

a plurality of subscriber units each having a subscriber ID;

b) receiving a communication from one of the plurality of subscriber units at one of the plurality of stationary base stations, wherein the communication includes the subscriber ID of the one of the plurality of subscriber units and the station ID of the one of the plurality of stationary base stations;

c) determining location of the one of the plurality of stationary base stations;

d) moving the mobile base station towards the location of the one of the plurality of stationary base stations and, at a first location, rotating the rotatably mounted directional antenna to selectively provide a selected communication coverage area about the first location;

e) receiving a first plurality of call handoff communications and subscriber IDs from a corresponding plurality of subscriber units including the one of the plurality of subscriber units;

f) storing a first direction of the rotatably mounted directional antenna and the first location of the mobile base station when the subscriber ID of the one of the plurality of subscriber units is received;

g) moving the mobile base station to a second location different from the first location and rotating the rotatably mounted directional antenna to selectively provide a selected communication coverage area about the second location;

h) receiving a second plurality of call handoff communications and subscriber IDs from a corresponding plurality of subscriber units including the one of the plurality of subscriber units;

i) storing a second direction of the rotatably mounted directional antenna and the second location of the mobile base station when the subscriber ID of the one of the plurality of subscriber units is received;

j) determining the location of the one of the plurality of subscriber units using the first and second locations and the first and second stored directions of the rotatably mounted directional antenna.

2. A method according to claim 1 where step (j) comprises the step of using a triangulation process.

3. A method for locating a subscriber unit in a cellular communication system, the cellular communication system including a plurality of stationary base stations each having a station ID, at least one mobile base station coupled to the plurality of stationary base stations, the at least one mobile base station having a rotatably mounted directional antenna, and a plurality of subscriber units each having a subscriber ID, the method comprising the steps of:

a) receiving a communication from one of the plurality of subscriber units at one of the plurality of stationary base stations, wherein the communication includes the subscriber ID of the one of the plurality of subscriber units and the station ID of the one of the plurality of stationary base stations;

b) determining location of the one of the plurality of stationary base stations;

c) at a first location wherein the mobile station has been moved towards the location of the one of the plurality of stationary base stations, rotating the rotatably mounted directional antenna to selectively provide a selected communication coverage area about the first location;

d) receiving a first plurality of call handoff communications and subscriber IDs from a corresponding plurality of subscriber units including the one of the plurality of subscriber units;

e) storing a first direction of the rotatably mounted directional antenna and the first location of the mobile base station when the subscriber ID of the one of the plurality of subscriber units is received;

f) at a second location wherein the mobile station has been moved towards the location of the one of the plurality of stationary base stations different from the first location, rotating the rotatably mounted directional antenna to selectively provide a selected communication coverage area about the second location;

g) receiving a second plurality of call handoff communications and subscriber IDs from a corresponding plurality of subscriber units including the one of the plurality of subscriber units;

h) storing a second direction of the rotatably mounted directional antenna and the second location of the mobile base station when the subscriber ID of the one of the plurality of subscriber units is received; and

i) determining the location of the one of the plurality of subscriber units using the first and second locations and the first and second stored directions of the rotatably mounted directional antenna.

4. A method according to claim 3 where step (i) comprises the step of using a triangulation process.

5. An apparatus for locating a subscriber unit in a cellular communication system, the cellular communication system including a plurality of stationary base stations each having a station ID, at least one mobile base station coupled to the plurality of stationary base stations, the at least one mobile base station having a rotatably mounted directional antenna, and a plurality of subscriber units each having a subscriber ID, the apparatus comprising:

a) means for receiving a communication from one of the plurality of subscriber units at one of the plurality of stationary base stations, wherein the communication includes the subscriber ID of the one of the plurality of subscriber units and the station ID of the one of the plurality of stationary base stations;

b) means for determining location of the one of the plurality of stationary base stations;

c) at a first location wherein the mobile station has been moved towards the location of the one of the plurality of stationary base stations, means for rotating the rotatably mounted directional antenna to selectively provide a selected communication coverage area about the first location;

d) means for receiving a first plurality of call handoff communications and subscriber IDs from a corresponding plurality of subscriber units including the one of the plurality of subscriber units;

e) means for storing a first direction of the rotatably mounted directional antenna and the first location of the mobile base station when the subscriber ID of the one of the plurality of subscriber units is received;

f) at a second location wherein the mobile station has been moved towards the location of the one of the plurality of stationary base stations different from the first location, means for rotating the rotatably mounted directional antenna to selectively provide a selected communication coverage area about the second location;

g) means for receiving a second plurality of call handoff communications and subscriber IDs from a corresponding plurality of subscriber units including the one of the plurality of subscriber units;

h) means for storing a second direction of the rotatably mounted directional antenna and the second location of the mobile base station when the subscriber ID of the one of the plurality of subscriber units is received; and

i) means for determining the location of the one of the plurality of subscriber units using the first and second locations and the first and second stored directions of the rotatably mounted directional antenna.

6. An apparatus according to claim 5, wherein the means for determining the location of the one of the plurality of subscriber units comprises a triangulation process.