Estimating proximity to a mobile station by manipulating an interfering signal

• US 9,173,064 B1
• Filed: 10/06/2014
• Issued: 10/27/2015
• Est. Priority Date: 10/06/2014
• Status: Active Grant

• Current Assignee: Polaris Wireless Incorporated
• Original Assignee: Polaris Wireless Incorporated
• Inventors: Spain, David Stevenson Jr.
• Primary Examiner(s): HUYNH, NAM TRUNG
• Application Number:
  US14/507,425
• Time in Patent Office: 386 Days
• US Class Current: 1/1
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/023 using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
• CPC Class Codes: H04W 4/025 using location based information parameters
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 84/042 Public Land Mobile systems, e.g. cellular systems

Abstract

A technique for providing a location estimate of a mobile station, with increased accuracy. An unenhanced estimate of the location of a target mobile station is first obtained. A portable transmitter is then situated in an initial geographic area of interest defined by the unenhanced estimate. The portable transmitter is then tuned to transmit on a particular neighbor base station frequency being reported by the mobile station. When the portable transmitter is moved close enough to the target mobile station, the mobile station stops reporting the neighbor to the mobile'"'"'s wireless telecommunications network, on account of the interference introduced by the portable transmitter being on that frequency. The estimated distance from the portable transmitter to the target mobile station depends on the transmit signal strength used by the portable transmitter. By considering these details, an enhanced estimate of the location of the mobile station can then be deduced.

Claims

1. A method comprising:

receiving, by a server computer, a measurement report generated by a mobile station;

deducing, by the server computer, a degree of proximity, P_T, of i) a first transmitter that transmits a first signal at a first radio frequency, to ii) the mobile station, based on whether signal-strength information for a second signal that is being transmitted by a source other than the first transmitter and at the first radio frequency, is absent from the measurement report because of the first signal being transmitted; and

generating, by the server computer, a location estimate of the mobile station based on the deduced degree of proximity, P_T, of the first transmitter to the mobile station.

2. The method of claim 1 wherein the location estimate is further based on a first transmit strength at which the first signal is transmitted when the measurement report is generated.

3. The method of claim 2 wherein the location estimate is further based on the location of the first transmitter where it transmits the first signal at the first transmit strength.

4. The method of claim 1 further comprising:

obtaining, by the server computer, an initial location estimate of the mobile station; and

assigning, by the server computer, the first radio frequency based on the initial location estimate of the mobile station, prior to the receiving of the measurement report.

5. The method of claim 1 further comprising:

if signal-strength information for the second signal is present in the measurement report for a given transmit strength of the first signal, increasing the transmit strength according to a series of steps; and

correlating the series of steps of increased transmit strength with a series of received measurement reports, in order to determine when the signal-strength information for the second signal becomes absent from the series of received measurement reports;

wherein the location estimate of the mobile station is further based on the transmit strength at which the signal-strength information for the second signal becomes absent.

6. The method of claim 5 further comprising generating, by the server computer, an instruction for moving the first transmitter, based on the transmit strength at which the signal-strength information for the second signal becomes absent.

7. The method of claim 1 further comprising transmitting, by the server computer, the location estimate of the mobile station.

8. A method comprising:

increasing, according to a series of steps, the transmit strength of a first signal transmitted by a first transmitter at a first radio frequency; and

receiving, by a server computer, a series of measurement reports generated by a mobile station;

correlating, by the server computer, the series of steps of increased transmit strength with the series of received measurement reports, in order to determine when signal-strength information corresponding to a second signal becomes absent from the series of received measurement reports, wherein the second signal is being transmitted by a source other than the first transmitter and at the first radio frequency; and

generating, by the server computer, a location estimate of the mobile station based on the transmit strength at which the signal-strength information for the second signal becomes absent.

9. The method of claim 8 wherein the location estimate is further based on the location of the first transmitter where it transmits the first signal at one or more of the stepped transmit strengths.

10. The method of claim 8 further comprising:

obtaining, by the server computer, an initial location estimate of the mobile station; and

assigning, by the server computer, the first radio frequency based on the initial location estimate of the mobile station, prior to the increasing of the transmit strength.

11. The method of claim 8 further comprising generating, by the server computer, an instruction for moving the first transmitter, based on the transmit strength at which the signal-strength information for the second signal becomes absent.

12. The method of claim 8 further comprising transmitting, by the server computer, the location estimate of the mobile station.

13. An apparatus comprising:

a receiver configured to receive a measurement report generated by a mobile station; and

a processor configured to

a) deduce a degree of proximity, P_T, of i) a first transmitter that transmits a first signal at a first radio frequency, to ii) the mobile station, based on whether signal-strength information for a second signal that is being transmitted by a source other than the first transmitter and at the first radio frequency, is absent from the measurement report because of the first signal being transmitted, and

b) generate a location estimate of the mobile station based on the deduced degree of proximity, P_T, of the first transmitter to the mobile station.

14. The apparatus of claim 13 wherein the processor is further configured to generate the location estimate based on a first transmit strength at which the first signal is transmitted when the measurement report is generated.

15. The apparatus of claim 14 wherein the processor is further configured to generate the location estimate based on the location of the first transmitter where it transmits the first signal at the first transmit strength.

16. The apparatus of claim 13 wherein the processor is further configured to:

obtain an initial location estimate of the mobile station; and

assign the first radio frequency based on the initial location estimate of the mobile station, prior to the receiving of the measurement report.

17. The apparatus of claim 13 further comprising a transmitter configured to transmit the location estimate of the mobile station.

18. A system comprising:

a transmitter configured to transmit a first signal at a first radio frequency, increasing, according to a series of steps, the transmit strength of the transmitted first signal; and

a server computer configured to

a) receive a series of measurement reports generated by a mobile station,

b) correlate the series of steps of increased transmit strength with the series of received measurement reports, in order to determine when signal-strength information corresponding to a second signal becomes absent from the series of received measurement reports, wherein the second signal is being transmitted by a source other than the first transmitter and at the first radio frequency, and

c) generate a location estimate of the mobile station based on the transmit strength at which the signal-strength information for the second signal becomes absent.

19. The system of claim 18 wherein the server computer is further configured to generate the location estimate based on the location of the first transmitter where it transmits the first signal at one or more of the stepped transmit strengths.

20. The system of claim 18 wherein the server computer is further configured to:

obtain an initial location estimate of the mobile station; and

assign the first radio frequency based on the initial location estimate of the mobile station, prior to the increasing of the transmit strength.

21. The system of claim 18 wherein the server computer is further configured to generate an instruction for moving the first transmitter, based on the transmit strength at which the signal-strength information for the second signal becomes absent.

22. The system of claim 18 wherein the server computer is further configured to transmit the location estimate of the mobile station.