Method and system for mobile location detection using handoff information

• US 7,366,492 B1
• Filed: 05/03/2002
• Issued: 04/29/2008
• Est. Priority Date: 05/03/2002
• Status: Expired due to Fees

• Current Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Original Assignee: BBN Technologies (Rtx Corporation), Verizon Corporate Services Group Incorporated (Verizon Communications Inc.)
• Inventors: Ganesh, Rajamani
• Primary Examiner(s): Nguyen; Duc M.
• Assistant Examiner(s): Addy; Anthony S.
• Application Number:
  US10/138,273
• Time in Patent Office: 2,188 Days
• Field of Search: 455/432.1, 455/436, 455/442, 4554561-4566, 455516-517, 455/521, 455/524, 455/404.1, 455/404.2, 455/522, 342/457
• US Class Current: 455/404.2
• CPC Class Codes: G01S 5/0205 Details
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Methods and systems for mobile station location detection. A mobile station measures signal strength of each of a set of signals associated with the mobile station, then determines whether a number of signals in the set is less than a predetermined threshold. Based on the determination, the mobile station calculates a difference in power between a first and second signal associated with the mobile station. Thereafter, power on a channel corresponding to the mobile station is increased for a predetermined number of frames based on the calculation. The location of the mobile station is determined during the power increase.

Claims

1. A method for mobile station location detection, comprising:

measuring signal strength of each of a set of signals associated with a mobile station and one or more base stations;

determining whether a number of signals in the set is less than a predetermined threshold;

calculating a difference in power between a first and second signal in the set based on the determination;

increasing power on a channel corresponding to the mobile station in response to one or more power control messages from the one or more base stations, respectively, the power increase being based on the calculation and lasting for a predetermined number of frames, wherein the predetermined number of frames is a performance parameter set by a network administrator, network performance engineer or other user based on call setup time and duration of speech in one frame, and wherein a location of the mobile station is determined during the power increase; and

preventing reduction in the power increase during the predetermined number of frames by programming the one or more base stations to stop issuing power control messages during the predetermined number of frames.

2. The method of claim 1, wherein the set of signals is a candidate set of pilot signals associated with the mobile station.

3. The method of claim 1, wherein the predetermined threshold varies dependent on a handoff status of the mobile station.

4. The method of claim 3, wherein the predetermined threshold is three when the mobile station is in a single handoff mode.

5. The method of claim 4, wherein the first signal is a strongest pilot signal in an active set of pilot signals associated with the mobile station, and the second signal is a second strongest pilot signal in a neighbor set of pilot signals associated with the mobile station.

6. The method of claim 4, wherein the first signal is a strongest pilot signal in an active set of pilot signals associated with the mobile station, and the second signal is a strongest pilot signal in a neighbor set of pilot signals associated with the mobile station.

7. The method of claim 4, wherein the first signal is a strongest pilot signal and the second signal is the fourth strongest pilot signal in a combined set of pilot signals associated with the mobile station, the combined set of pilot signals including an active set of pilot signals and a candidate set of pilot signals.

8. The method of claim 3, wherein the predetermined threshold is two when the mobile station is in a two-way handoff mode.

9. The method of claim 8, wherein the first signal is a second strongest pilot signal in an active set of pilot signals associated with the mobile station, and the second signal is a strongest pilot signal in a neighbor set of pilot signals associated with the mobile station.

10. The method of claim 8, wherein the first signal is a second strongest pilot signal and the second signal is the fourth strongest pilot signal in a combined set of pilot signals associated with the mobile station, the combined set of pilot signals including an active set of pilot signals and a candidate set of pilot signals.

11. The method of claim 3, wherein the predetermined threshold is one when the mobile station is in a three-way handoff mode.

12. The method of claim 11, wherein the first signal is a third strongest pilot signal and the second signal is the fourth strongest pilot signal in a combined set of pilot signals associated with the mobile station, the combined set of pilot signals including an active set of pilot signals and a candidate set of pilot signals.

13. The method of claim 1, wherein the predetermined number of frames is a number such that a base station does not have enough time to command a power decrease on the channel before the predetermined number of frames has elapsed.

14. The method of claim 1, wherein the channel is a reverse traffic channel.

15. The method of claim 1, wherein the power increase is greater when the number of signals in the set is less than the predetermined threshold than the power increase when the number of signals in the set is greater than or equal to the predetermined threshold.

16. A method for mobile station location detection, comprising:

initiating an emergency services call from a mobile station to one or more base stations;

measuring signal strength of each of a set of signals associated with the call;

determining whether a number of signals in the set is less than a predetermined threshold based on a handoff status of the mobile station;

calculating a difference in power between a first and second signal in the set based on the determination;

increasing power on a channel corresponding to the mobile station in response to one or more power control messages from the one or more base stations, respectively, the power increase being based on the calculation and lasting for a predetermined number of frames, wherein the predetermined number of frames is a performance parameter set by a network administrator, network performance engineer or other user based on call setup time and duration of speech in one frame, and wherein a location of the mobile station is determined during the power increase; and

preventing reduction in the power increase during the predetermined number of frames by programming the one or more base stations to stop issuing power control messages during the predetermined number of frames.

17. An apparatus for use in mobile station location detection, comprising:

means for measuring signal strength of each of a set of signals associated with a mobile station and one or more base stations;

means for determining whether a number of signals in the set is less than a predetermined threshold;

means for calculating a difference in power between a first and second signal in the set based on the determination;

means for increasing power on a channel corresponding to the mobile station in response to one or more power control messages from the one or more base stations, respectively, the power increase being based on the calculation for a predetermined number of frames, wherein the predetermined number of frames is a performance parameter set by a network administrator, network performance engineer or other user based on call setup time and duration of speech in one frame, and wherein a location of the mobile station is determined during the power increase; and

preventing reduction in the power increase during the predetermined number of frames by programming the one or more base stations to stop issuing power control messages during the predetermined number of frames.

18. The apparatus of claim 17, wherein the set of signals is a candidate set of pilot signals associated with the mobile station.

19. The apparatus of claim 17, wherein the predetermined threshold varies dependent on a handoff status of the mobile station.

20. The apparatus of claim 19, wherein the predetermined threshold is three when the mobile station is in a single handoff mode.

21. The apparatus of claim 20, wherein the first signal is a strongest pilot signal in an active set of pilot signals associated with the mobile station, and the second signal is a second strongest pilot signal in a neighbor set of pilot signals associated with the mobile station.

22. The apparatus of claim 20, wherein the first signal is a strongest pilot signal in an active set of pilot signals associated with the mobile station, and the second signal is a strongest pilot signal in a neighbor set of pilot signals associated with the mobile station.

23. The apparatus of claim 20, wherein the first signal is a strongest pilot signal and the second signal is the fourth strongest pilot signal in a combined set of pilot signals associated with the mobile station, the combined set of pilot signals including an active set of pilot signals and a candidate set of pilot signals.

24. The apparatus of claim 19, wherein the predetermined threshold is two when the mobile station is in a two-way handoff mode.

25. The apparatus of claim 24, wherein the first signal is a second strongest pilot signal in an active set of pilot signals associated with the mobile station, and the second signal is a strongest pilot signal in a neighbor set of pilot signals associated with the mobile station.

26. The apparatus of claim 24, wherein the first signal is a second strongest pilot signal and the second signal is the fourth strongest pilot signal in a combined set of pilot signals associated with the mobile station, the combined set of pilot signals including an active set of pilot signals and a candidate set of pilot signals.

27. The apparatus of claim 19, wherein the predetermined threshold is one when the mobile station is in a three-way handoff mode.

28. The apparatus of claim 27, wherein the first signal is a third strongest pilot signal and the second signal is the fourth strongest pilot signal in a combined set of pilot signals associated with the mobile station, the combined set of pilot signals including an active set of pilot signals and a candidate set of pilot signals.

29. The apparatus of claim 17, wherein the predetermined number of frames is a number such that a base station does not have enough time to command a power decrease on the channel before the predetermined number of frames has elapsed.

30. The apparatus of claim 17, wherein the channel is a reverse traffic channel.

31. The apparatus of claim 17, wherein the power increase is greater when the number of signals in the set is less than the predetermined threshold than the power increase when the number of signals in the set is greater than or equal to the predetermined threshold.

32. An apparatus for use in mobile station location detection, comprising:

means for initiating an emergency services call from a mobile station to one or more base stations;

means for measuring signal strength of each of a set of signals associated with the call;

means for determining whether a number of signals in the set is less than a predetermined threshold based on a handoff status of the mobile station;

means for calculating a difference in power between a first and second signal in the set based on the determination;

means for increasing power on a channel corresponding to the mobile station in response to one or more power control messages from the one or more base stations, respectively, the power increase being based on the calculation and lasting for a predetermined number of frames, wherein the predetermined number of frames is a performance parameter set by a network administrator, network performance engineer or other user based on call setup time and duration of speech in one frame, and wherein a location of the mobile station is determined during the power increase; and

preventing reduction in the power increase during the predetermined number of frames by programming the one or more base stations to stop issuing power control messages during the predetermined number of frames.

33. A method for mobile station location detection, comprising:

initiating a call from a mobile station to one or more base stations;

measuring signal strength of each of a set of signals associated with the call;

determining whether a number of signals in the set is less than a predetermined threshold based on a handoff status of the mobile station;

calculating a difference in power between a first and second signal in the set based on the determination;

increasing power on a channel corresponding to the mobile station in response to one or more power control messages from the one or more base stations, respectively, the power increase being based on the calculation and lasting for a predetermined number of frames wherein the predetermined number of frames is a performance parameter set by a network administrator, network performance engineer or other user based on call setup time and duration of speech in one frame;

preventing reduction in the power increase during the predetermined number of frames by programming the one or more base stations to stop issuing power control messages during the predetermined number of frames; and

determining, during the power increase, a location of the mobile station using a technique based on a difference in arrival time of a signal from the mobile station at separate ones of the base stations.