Method and system for locating mobile stations using call measurement data

• US 8,346,282 B1
• Filed: 04/02/2012
• Issued: 01/01/2013
• Est. Priority Date: 12/30/2008
• Status: Active Grant

• Current Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Dronamraju, Srirama Krishna, Lall, Abhishek, Srinivasamurthy, Vishu
• Primary Examiner(s): Zewdu, Meless N
• Assistant Examiner(s): Chambers, Tangela T.
• Application Number:
  US13/437,165
• Time in Patent Office: 274 Days
• Field of Search: 4554561-4562, 4554565-4566
• US Class Current: 455/456.1
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A location of a mobile station is estimated based on wireless communications between the mobile station and a wireless telecommunications network. Call measurement data is obtained for a call involving the mobile station and a plurality of base station antennas. The call measurement data includes round-trip delay (RTD) measurements and received signal strength (RSS) measurements. The most significant one or more base station antennas involved in the call are identified. An expected signal strength is calculated for each significant base station antenna, according to a wireless propagation model that accounts for terrain around the base station antennas. For each significant base station antenna, the corresponding expected signal strength, RTD measurement, and RSS measurement are used to calculate an adjusted RTD value. The one or more adjusted RTD values calculated for the one or more significant base station antennas are used to estimate the mobile station'"'"'s location.

Claims

1. A method, comprising:

for each antenna in a plurality of base station antennas in a wireless telecommunications network, obtaining a respective significance value for said antenna based, at least in part, on delay and signal strength measurements for a wireless signal transmitted by said antenna and received by a mobile station, so as to obtain a plurality of significance values;

identifying at least one significant base station antenna from among said plurality of base station antennas based on said significance values;

obtaining at least one expected signal strength for said at least one significant base station antenna; and

determining an estimated location of said mobile station based on an adjusted delay value for said at least one significant base station antenna, wherein said adjusted delay value is based, at least in part, on said at least one expected signal strength for said at least one significant base station antenna.

2. The method of claim 1, wherein said delay and signal strength measurements are obtained from measurement data for a call involving said mobile station.

3. The method of claim 1, wherein identifying at least one significant base station antenna from among said plurality of base station antennas based on said significance values comprises:

for each antenna in said plurality of base station antennas;

determining whether said respective significance value for said antenna exceeds a predetermined threshold value, and

in response to determining that said respective significance value for said antenna exceeds said predetermined threshold value, identifying said antenna as a significant base station antenna.

4. The method of claim 1, wherein obtaining said respective significance value for said antenna based, at least in part, on said delay and signal strength measurements for said wireless signal transmitted by said antenna comprises:

obtaining a reference signal strength for said antenna; and

calculating said respective significance value for said antenna based on said reference signal strength and said delay and signal strength measurements.

5. The method of claim 4, wherein obtaining said reference signal strength for said antenna comprises:

selecting a reference location for said antenna; and

calculating said reference signal strength as a signal strength at said reference location of a signal transmitted by said antenna, according to a wireless propagation model.

6. The method of claim 5, wherein said wireless propagation model accounts for terrain around said antenna.

7. The method of claim 5, wherein said reference location comprises a fixed location.

8. The method of claim 5, wherein said reference location comprises a location selected based on a delay measurement reported for said antenna.

9. The method of claim 1, wherein determining said estimated location of said mobile station based on said adjusted delay value for said at least one significant base station antenna, and wherein determining said estimated location of said mobile station based on said adjusted delay value comprises:

using a neural network model to calculate said adjusted delay value based on antenna parameters comprising;

a parameter for expected signal strength for a first significant base station antenna of said plurality of base station antennas, a parameter for a measured signal strength corresponding to said first significant base station antenna, and a parameter for a delay measurement corresponding to said first significant base station antenna.

10. A network, comprising:

a plurality of base station antennas configured to communicate with a plurality of mobile stations; and

a location processor, configured to;

select a mobile station of said plurality of mobile stations,

obtain delay and signal strength measurements for wireless signals transmitted by said plurality of base station antennas and received by said selected mobile station,

for each antenna of said plurality of base station antennas, obtaining a respective significance value for said antenna based, at least in part, on said delay and signal strength measurements, so as to obtain a plurality of significance values,

identify at least one significant base station antenna from among said plurality of base station antennas based on said significance values,

obtain at least one expected signal strength for said at least one significant base station antenna, and

determine an estimated location of said selected mobile station based on an adjusted delay value for said at least one significant base station antenna, wherein said adjusted delay value is based, at least in part, on said at least one expected signal strength for said at least one significant base station antenna.

11. The network of claim 10, wherein said location processor is configured to estimate a location of said selected mobile station at periodic time intervals.

12. The network of claim 10, wherein said delay and signal strength measurements are obtained from measurement data for a call involving said selected mobile station.

13. The network of claim 10, wherein said location processor is configured to identify at least one significant base station antenna from among said plurality of base station antennas based on said significance values by a process comprising:

for each antenna in said plurality of base station antennas;

determining whether said respective significance value for said antenna exceeds a predetermined threshold value, and

in response to determining that said respective significance value for said antenna exceeds said predetermined threshold value, identifying said antenna as a significant base station antenna.

14. The network of claim 10, wherein said location processor is configured to obtain said respective significance value for said antenna based, at least in part, said delay and signal strength measurements by a process comprising:

obtaining a reference signal strength for said antenna; and

calculating said respective significance value for said antenna based on said reference signal strength and said delay and signal strength measurements.

15. The network of claim 10, wherein said location processor comprises a neural network model, and wherein determining said estimated location of said selected mobile station based on said adjusted delay value comprises:

using said neural network model of said location processor to calculate said adjusted delay value based on antenna parameters comprising;

a parameter for expected signal strength for a first significant base station antenna of said plurality of base station antennas, a parameter for a measured signal strength corresponding to said first significant base station antenna, and a parameter for a delay measurement corresponding to said first significant base station antenna.