METHOD AND APPARATUS FOR LOCATING A WIRELESS USER

• US 20080219233A1
• Filed: 05/19/2008
• Published: 09/11/2008
• Est. Priority Date: 09/06/1994
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: LaVean, Gilbert E., Bolgiano, D. Ridgely
• Granted Patent: US 8,155,017 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• 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: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/082 selecting best antenna path
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04B 7/0888 with selection
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A plurality of antennas transmit a first spread spectrum signal having an associated code. The first spread spectrum signal is received at the wireless user. For each received first spread spectrum signal, a second spread spectrum signal is transmitted having an associated code having a same phase as that received first spread spectrum signal. The second spread spectrum signals are received at the plurality of antennas. A distance measurement is determined between each antenna and the wireless user based on in part a received timing of the second signals. The wireless user'"'"'s location is determined based on in part the distance determinations.

Claims

1. A method for use in a subscriber unit, the method comprising:

receiving a first signal from a first base station;

receiving a second signal from a second base station;

measuring a difference between a first time of arrival of the first signal and a second time of arrival of the second signal; and

transmitting a third signal carrying information indicative of the difference between the first and second times of arrival to a base station associated with one of the first and second base stations, wherein the third signal is spread coded.

2. The method of claim 1, wherein the first signal is encoded with a first pseudorandom code and the second signal is encoded with a second pseudorandom code.

3. The method of claim 2, wherein a portion of the first pseudorandom code carried by the first signal arrives at the subscriber a number of chips before a portion of the second pseudorandom code carried by the second signal, the number of chips corresponding to the difference between the first and second times of arrival.

4. The method of claim 1, wherein the first and second signals carry data.

5. The method of claim 1, further comprising displaying a location of the subscriber unit, wherein the location of the subscriber unit is based on the difference between the first and second times of arrival.

6. The method of claim 1, further comprising generating an audible signal, wherein the audible signal indicates a location of the subscriber unit that is based on the difference between the first and second times of arrival.

7. The method of claim 1, further comprising displaying instructions for reaching a destination address.

8. The method of claim 7, further comprising modifying the instructions in response to changes in traffic congestion.

9. The method of claim 1, further comprising displaying a destination address.

10. A code division multiple access (CDMA) subscriber unit comprising:

an antenna configured to receive a first signal from a first base station and a second signal from a second base station; and

a circuit operatively coupled to the receiver configured to measure a difference between a first time of arrival of the first signal and a second time of arrival of the second signal;

wherein the circuit is further configured to transmit a spread coded third signal carrying information indicative of the difference between the first and second times of arrival to a base station associated with one of the first and second base stations using the antenna.

11. The CDMA subscriber unit of claim 10, wherein the first signal is encoded with a first pseudorandom code and the second signal is encoded with a second pseudorandom code.

12. The CDMA subscriber of claim 11, wherein a portion of the first pseudorandom code carried by the first signal arriving at the subscriber a number of chips before a portion of the second pseudorandom code carried by the second signal, the number of chips corresponding to the difference between the first and second times of arrival.

13. The CDMA subscriber unit of claim 10, wherein the first and second signals carry data.

14. The CDMA subscriber unit of claim 10 further comprising a display configured to display a location of the subscriber unit, wherein the location is based on the difference between the first and second times of arrival.

15. The CDMA subscriber unit of claim 10 further comprising a speaker configured to generate an audible signal, wherein the audible signal indicates a location of the subscriber unit that is based on the difference between the first and second times of arrival.

16. The CDMA subscriber unit of claim 10 further comprising a display configured to display instructions for reaching a destination address.

17. The CDMA subscriber unit of claim 16, wherein the display is configured to modify the instructions in response to changes in traffic congestion.

18. The CDMA subscriber unit of claim 10 further comprising a display configured to display a destination address.

19. A code division multiple access (CDMA) subscriber unit comprising:

an antenna configured to receive a first signal from a first base station and a second signal from a second base station, wherein the first signal is spread coded in accordance with a first pseudorandom code and the second signal being spread coded in accordance with a second pseudorandom code; and

a circuit operatively coupled to the receiver configured to measure a difference, in chips, between a first arrival time of a portion of the first pseudorandom code carried by first signal and a second arrival time of a portion of the second pseudorandom code carried by the second signal;

wherein the circuit is further configured to transmit a spread coded third signal carrying information indicative of the difference between the first and second arrival times to a base station associated with one of the first and second base station using the antenna.

20. The CDMA subscriber unit of claim 19 further comprising a display configured to display a location of the subscriber unit, wherein the location is based on the difference between the first and second times of arrival.

21. The CDMA subscriber unit of claim 19 further comprising a speaker configured to generate an audible signal, wherein the audible signal indicates a location of the subscriber unit that is based on the difference between the first and second times of arrival.

22. The CDMA subscriber unit of claim 19 further comprising a display configured to display instructions for reaching a destination address.

23. The CDMA subscriber unit of claim 22, wherein the display is configured to modify the instructions in response to changes in traffic congestion.

24. The CDMA subscriber unit of claim 19 further comprising a display configured to display a destination address.

25. The CDMA subscriber unit of claim 19, wherein the first and second signals carry data.