Wireless communication system having base station with adjustable power transceiver for locating mobile devices

• US 5,924,040 A
• Filed: 11/20/1996
• Issued: 07/13/1999
• Est. Priority Date: 11/20/1996
• Status: Expired due to Term

• Current Assignee: Cisco Systems, Inc.
• Original Assignee: Telxon Corporation (Zebra Technologies Corporation)
• Inventors: Trompower, Michael L.
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/752,906
• Time in Patent Office: 965 Days
• Field of Search: 455/422, 455/456, 455/458, 455/561, 455/562, 342/357, 342/457
• US Class Current: 455/456.2
• CPC Class Codes: G01S 5/01 Determining conditions which influence positioning, e.g. radio environment, state of motion or energy consumption
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A network cellular communication system with power based locator system in which the location of a mobile communication unit within the network can be determined approximately. In particular, the power based locator system includes a pre-stored map of locations of a plurality of base stations within the network and the respective network cell coverage areas for those base stations. Each of the plurality of base stations is able to change the size of its respective cell by varying transmitter and receiver power levels. By incrementally changing its respective cell coverage area, the base station can effectively narrow down the region in which a mobile communication unit is located. The region information is correlated with the pre-stored map of locations to determine approximately where in the cellular communication network the mobile communication unit is located.

Claims

1. A method of locating a mobile communication unit within a network cellular communication system comprising the steps of:

using a host computer to initiate a mobile communication unit location request to at least one base station;

using the at least one base station to monitor for the mobile communication unit, the base station including circuitry for adjusting a power level of signals being communicated by the base station, wherein the base station upon locating the mobile communication unit varies the power level whereby a size of a cell coverage area of the base station is varied in order to determine approximately the location of the mobile communication unit with respect to the at least one base station;

using the at least one base station to send the mobile communication unit location information to the host computer; and

using the host computer to process the mobile communication unit location information received from the at least one base station in order to determine the location of the mobile communication unit with respect to the network;

wherein the host computer correlates the information received from the at least one base station with a pre-stored map to determine the location of the mobile communication unit with respect to the network.

2. The method of claim 1 wherein the map includes the location of the at least one base station with respect to the network.

3. The method of claim 2 wherein the map includes the location information of a plurality of cell coverage areas of the at least one base station.

4. A cellular communication system, comprising:

at least one base station having a communication cell coverage area, the at least one base station being coupled to a system backbone, the at least one base station including a receiving system for receiving wireless communications and a transmitting system for transmitting wireless communications, the at least one base station including a first antenna and circuitry for adjusting the cell coverage area of signals being transmitted or received by the first antenna;

at least one mobile communication unit for communicating with the system backbone via the at least one base station, the at least one mobile communication unit having a mobile communication unit transmitter for transmitting wireless communications to the at least one base station and a mobile communication unit receiver system for receiving wireless communications from the at least one base station;

wherein, the at least one base station can vary its cell coverage area so that the system can determine approximately where the at least one mobile communication unit is located with respect to the base station; and

a host computer for receiving from the at least one base station the location information of the mobile communication unit with respect to the base station, wherein the host computer upon receiving the location information of the mobile communication unit with respect to the base station processes the information in conjunction with pre-stored map information to determine the location of the mobile communication unit within the network, the pre-stored map information including information relating to the location of the at least one base station within the network.

5. The cellular communication system of claim 4 wherein the pre-stored map information further includes information relating to the location of a plurality of cell coverage areas of the at least one base station.

6. The cellular communication system of claim 4 wherein the cell coverage area is varied by changing the power level of the signal being transmitted by the first antenna.

7. The cellular communication system of claim 4 wherein the first antenna is a directional antenna.

8. The cellular communication system of claim 7 wherein the cell coverage area is varied by changing the respective direction of the signal being transmitted by the first antenna.

9. The cellular communication system of claim 8 wherein the respective direction of the signal is changed by selectively rotating the first antenna.

10. The cellular communication system of claim 8 wherein the first antenna is an omni-directional antenna.

11. The cellular communication system of claim 4 wherein the at least one base station has a second antenna.

12. The cellular communication system of claim 11 wherein the at least on base station employs both the first antenna and the second antenna to further determine the location of the at least one mobile communication unit.