Location determination using RF fingerprinting

• US 20030008668A1
• Filed: 04/22/2002
• Published: 01/09/2003
• Est. Priority Date: 09/22/1998
• Status: Active Grant

• Current Assignee: Polaris Wireless Incorporated
• Original Assignee: PNM Incorporated (Union Pacific Corporation)
• Inventors: Rao, Padmanabha R., Siccardo, Paolo, Dressler, Robert M., Spain, David S., Perez-Breva, Luis, Chong, Chee-Yee
• Granted Patent: US 6,782,265 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/0236 Assistance data, e.g. base station almanac
• CPC Class Codes: G01S 5/02526 using non-dedicated equipment, e.g. user equipment or crowd-sourcing
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method for determining the location of a mobile unit (MU) in a wireless communication system and presenting it to a remote party. The location of a remote MU is determined by comparing a snapshot of a predefined portion of the radio-frequency (RF) spectrum taken by the MU to a reference database containing multiple snapshots taken at various locations. The result of the comparison is used to determine if the MU is at a specific location. The comparison may be made in the MU, or at some other location situated remotely from the MU. In the latter case, sufficient information regarding the captured fingerprint is transmitted from the MU to the remote location. The database may be pre-compiled or generated on-line.

Claims

1. A method for locating the position of a mobile unit in a wireless communication network, the method comprising:

capturing a first fingerprint of the RF spectrum in the mobile unit;

comparing said first fingerprint with a multiplicity of fingerprints, each said multiplicity of fingerprints corresponding to a unique location;

selecting a second fingerprint from said multiplicity of fingerprints as the closest matching fingerprint to said first fingerprint; and

assigning a location corresponding to said second fingerprint to said mobile unit;

wherein said multiplicity of fingerprints is designed to take into account at least one dynamic, but predetermined, variation in the RF signal characteristics.

2. The method of claim 1 wherein said first and second fingerprints are generated using a predetermined portion of the RF spectrum.

3. The method of claim 1 wherein said first and second fingerprints are generated using a predetermined set of signal parameters.

4. The method of claim 1 wherein said multiplicity of fingerprints is stored in the mobile unit.

5. The method of claim 1 wherein said multiplicity of fingerprints is stored in an Other Party that is linked to the mobile unit via the wireless communication network.

6. The method of claim 5 wherein said first fingerprint is processed and transmitted over the wireless communication network to the Other Party.

7. The method of claim 4 wherein said location assignment is performed by the mobile unit.

8. The method of claim 6 wherein said location assignment is performed by the Other Party.

9. The method of claim 2 wherein said predetermined portion of the RF spectrum overlaps with the portion of the RF spectrum utilized by the wireless communication network.

10. The method of claim 2 wherein said predetermined portion of the RF spectrum overlaps with the portion of the spectrum utilized by commercial FM radio broadcasting stations.

11. The method of claim 1 wherein said first and second fingerprints are generated using a predetermined portion of the RF spectrum and a predetermined set of signal parameters.

12. The method of claim 1 wherein said multiplicity of fingerprints is calculated using RF prediction models or is generated from field measurements.

13. The method of claim 1 wherein a time series of said first fingerprints is matched with said multiplicity of fingerprints to determine a location time history for said mobile unit.

15. The method of claim 14 wherein said multiplicity of fingerprints is calibrated using field measurements at pre-selected locations.

17. The method of claim 16 wherein information from an equalizer filter for wideband cellular signals is included in the RF fingerprint.

18. The method of claim 16 wherein a time series of said first fingerprints is matched with said multiplicity of fingerprints to determine a location time history for said mobile unit and Markov filtering is used in processing said time series of first fingerprints to determine position and velocity of the mobile unit.

19. The method of claim 16 wherein a time series of said first fingerprints is matched with said multiplicity of fingerprints to determine a location time history for said mobile unit and multiple hypothesis testing is used to determine said location time history with the highest probability for the mobile unit.

20. The method of claim 16, wherein ambiguity analysis of said multiplicity of fingerprints is performed to determine location accuracy for said mobile unit.

21. The method of claim 16 wherein SMS messages are used to send said first fingerprints from the mobile unit to the Other Party.

22. The method of claim 16 wherein SMS messages are used to send mobile unit position and velocity from the Other Party to the mobile unit.

14. A method for locating the position of a mobile unit in a wireless communication network, the method comprising:

capturing a first fingerprint of the RF spectrum in the mobile unit;

comparing said first fingerprint with a multiplicity of fingerprints, each said multiplicity of fingerprints corresponding to a unique location;

selecting a second fingerprint from said multiplicity of fingerprints as the closest matching fingerprint to said first fingerprint; and

assigning a location corresponding to said second fingerprint to said mobile unit;

wherein said multiplicity of fingerprints (i.e., fingerprint database) is corrected for co-channel and adjacent-channel interference.

16. A method for locating the position of a mobile unit in a wireless communication network, the method comprising:

capturing a first fingerprint of the RF spectrum in the mobile unit;

comparing said first fingerprint with a multiplicity of fingerprints, each said multiplicity of fingerprints corresponding to a unique location;

selecting a second fingerprint from said multiplicity of fingerprints as the closest matching fingerprint to said first fingerprint; and

assigning a location corresponding to said second fingerprint to said mobile unit;

wherein the accuracy of said multiplicity of fingerprints is improved by using learning/training techniques and related methodologies.