Location systems in cellular communication networks

• US 7,224,982 B2
• Filed: 11/15/2002
• Issued: 05/29/2007
• Est. Priority Date: 11/16/2001
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ormson, Richard
• Primary Examiner(s): Eng; George
• Assistant Examiner(s): Afshar; Kamran
• Application Number:
  US10/294,677
• Publication Number:
  US 20030096624A1
• Time in Patent Office: 1,656 Days
• Field of Search: 4554561-4566, 455/404.2, 455/433, 455/422.1, 342/357.01, 342/357.02, 342/450, 701/207, 340/426.19, 340/426.2, 340/539.13
• US Class Current: 455/456.1
• CPC Class Codes: G01S 1/026 of associated receivers
• CPC Class Codes: G01S 1/045 Receivers
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A location system in a cellular communication network has a first set of base stations which transmits and receives signals in a first communication format. The second set of base stations transmits and receives signals in a second communication format. All the base stations transmit known signals at predetermined times for use in deriving location data. A transmitting and receiving unit of the known location determines the times of arrivals of these signals from each base station in each set of base stations. Similarly, a mobile unit at an unknown location determines the times of arrival of the signals from each base station. By comparing timing differences between signals received at the unknown location and signals received at the known location, it is possible to determine the unknown location therefrom. This can then be transmitted back to either of the sets of base stations. In a situation where two communication networks are used, the mobile units will be dual mode transmitting and receiving units.

Claims

1. A location system for use in a cellular communication network comprising:

a first set of base stations transmittiug and receiving signals in a first communication format having a first time base;

a second set of base stations transmitting and receiving signals in a second communication format having a second time base, wherein all base stations transmit known signals at predetermined times for use in deriving location data;

a transmitting and receiving unit at a known location;

a transmitting and receiving unit at an unknown location;

means for determining times of arrival of the known signals from at least one base station in each of said first set of base stations and said second set of base stations at the known location;

means for determining the times of arrival of signals from at least one base station from each of said first set of base stations and said second set of base stations at the unit at the unknown location;

means for converting between said first time base and said second time base by measuring a time of a start of a transmission frame in said first time base, a frame number of said transmission frame in said first time base, a time of a start of transmission frame in said second time base, and a frame number of said transmission frame in said second time base;

means for comparing timing differences between signals received at the unknown location and signals received at the known location from each base station from each of said first set of base stations and said second set of base stations; and

means for determining the unknown location based upon said comparing.

2. The system as claimed in claim 1, in which the first set of base stations transmits using a Global System for Mobile Communications transmission network and the second set of base stations transmits using a Universal Mobile Transmission Standard transmission network.

3. The system as claimed in claim 2, in which the means for determining the unknown location is within one of the networks to which one of the sets of base stations is connected.

4. The system as claimed in claim 2, in which the means for determining the unknown location is in the unit at the unknown location.

5. The system as claimed in claim 1, in which the means for determining the unknown location is within one of the networks to which one of the sets of base stations is connected.

6. The system as claimed in claim 5, in which the means for determining the unknown location is in the unit at the unknown location.

7. The system as claimed in claim 1, in which the means for determining the unknown location is in the unit at the unknown location.

8. The system as claimed in claim 1, in which one of the sets of base stations transmits using a Global System for Mobile Communications transmission network and the second set of base stations transmits using a Universal Mobile Transmission Standard transmission network.

9. The system as claimed in claim 1, in which the means for determining the unknown location is within one of the networks to which one of the sets of base stations is connected.

10. The system as claimed in claim 1, in which the means for determining the unknown location is in the unit at the unknown location.

11. A dual mode transmitting and receiving unit for use with two cellular communication networks including a first cellular communication network having a first communication format with a first time base and a second cellular communication network having a second communication format with a second time base, each comprising a plurality of base stations for transmitting and receiving signals from units, the unit comprising means for converting between said first time base and said second time base by measuring a time of a start of a transmission frame in said first time base, a frame number of said transmission frame in said first time base, a time of a start of transmission frame in said second time base, and a frame number of said transmission frame in said second time base and deriving location data based upon communications from both cellular communication networks and said conversion.

12. A dual mode transmitting and receiving unit, comprising:

a transceiver for communicating with a first set of stations using a first communication format having a first time base and a second set of base stations using a second communication format having a second time base;

means for converting between said first time base and said second time base by measuring a time of a start of a transmission frame in said first time base, a frame number of said transmission frame in said first time base, a time of a start of transmission frame in said second time base, and a frame number of said transmission frame in said second time base; and

means for determining a location of said dual mode transmitting and receiving unit based upon a time of arrival of signals from both of said first set of base stations and said second set of base stations at a known location and a time of arrival of signals from both of said first set of base stations and said second set of base stations at said dual mode transmitting and receiving unit.

13. A location system for use in a cellular communication network comprising:

a transmitting and receiving unit at a known location;

a transmitting and receiving unit at an unknown location;

a first timer that determines a time of arrival of signals from a first set of base stations transmitting and receiving signals in a first communication format having a first time base and from a second set of base stations transmitting and receiving signals in a second communication format having a second time base at the known location;

a second timer that determines a time of arrival of signals from said first set of base stations and from said second set of base stations at the unknown location;

a processor that converts between said first time base and said second time base by measuring a time of a start of a transmission frame in said first time base, a frame number of said transmission frame in said first time base, a time of a start of transmission frame in said second time base, and a frame number of said transmission frame in said second time base and that determines the unknown location based upon the time of arrival of the signals from both of said first set of base stations and said second set of base stations at the known location and the time of arrival of the signals at the unknown location.

14. The system of claim 13, wherein at least one of said first timer and said second timer comprises:

a first set of electronics receiving said signals from said first set of base stations; and

a second set of electronics receiving said signals from said second set of base stations.

15. The system of claim 14, wherein a delay through the first set of electronics is substantially the same as a delay through the second set of electronics.

16. The system of claim 14, wherein at least one of said first set of electronics and said second set of electronics comprises an AND gate and a flip flop.

17. The system of claim 14, wherein said at least one of said first timer and said second timer further comprises:

an Exclusive OR gate receiving signals from each of said first set of electronics and said second set of electronics; and

a counter in communication with said Exclusive OR gate.

18. The system of claim 13, wherein said processor determines the unknown location based upon an offset between the time of arrival of the signals at the known location and the time of arrival of the signals at the unknown location.