Indoor localization using commercial frequency-modulated signals

• US 8,548,497 B2
• Filed: 12/16/2011
• Issued: 10/01/2013
• Est. Priority Date: 12/16/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Lymberopoulos, Dimitrios, Liu, Jie, Priyantha, Nissanka Arachchige Bodhi, Chen, Yin
• Primary Examiner(s): Afshar, Kamran
• Assistant Examiner(s): TRAN, MONG-THUY THI
• Application Number:
  US13/328,613
• Publication Number:
  US 20130157683A1
• Time in Patent Office: 655 Days
• Field of Search: 455/456.1, 455/404.2, 455/414.2, 455/456.3, 455/41.2, 455/456.6
• US Class Current: 455/456.1
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01S 5/02521 using a radio-map
• CPC Class Codes: H04W 4/33 for indoor environments, e.g. buildings
• CPC Class Codes: H04W 4/60 Subscription-based services using application servers or record carriers, e.g. SIM application toolkits
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A commercial frequency-modulated (FM) radio signal indoor localization system and method for finding a location of a mobile embedded device (such as a smartphone) within a building. Indoor localization is performed by receiving commercial FM radio signals on the device, analyzing the signals using signal quality metrics, and generating signal quality vectors for each signal and signal quality metric used for the signal. The signal quality metric can be any physical signal quality indicator. The signal quality vectors are added to obtain a current location fingerprint. The current location fingerprint is compared to fingerprints stored in a fingerprint database. The location associated with the stored fingerprint that is the closest match to the current fingerprint location is designated as the current location in the building of the mobile embedded device. Locally generated radio signals can be used in conjunction with the commercial FM radio signals to improve localization accuracy.

Claims

1. A computer system comprising:

one or more processing units; and

one or more computer storage media storing computer-executable instructions which, when executed by the one or more processing units, cause the one or more processing units to;

receive a commercial frequency-modulated radio signal on the computer system;

analyze a signal-to-noise ratio of the commercial frequency-modulated radio signal to obtain a signal quality vector comprising the signal-to-noise ratio of the commercial frequency-modulated radio signal;

analyze a multipath indicator of the commercial frequency-modulated radio signal to obtain another signal quality vector comprising the multipath indicator of the commercial frequency-modulated radio signal;

add the signal quality vector comprising the signal-to-noise ratio of the commercial frequency-modulated radio signal to a current location fingerprint;

add the another signal quality vector comprising the multipath indicator of the commercial frequency-modulated radio signal to the current location fingerprint; and

compare the current location fingerprint including the signal quality vector and the another signal quality vector to a fingerprint database to obtain a current location of the computer system.

2. The computer system of claim 1, wherein the current location is an indoor location within a structure.

3. The computer system of claim 1, wherein the computer-executable instructions cause the one or more processing units to:

analyze a received signal strength of the commercial frequency-modulated radio signal to obtain a further signal quality vector comprising a received signal strength of the commercial frequency-modulated radio signal; and

add the further signal quality vector to the current location fingerprint, wherein the current location fingerprint also includes the further signal quality vector when compared to the fingerprint database to obtain the current location.

4. The computer system of claim 1, wherein the computer-executable instructions cause the one or more processing units to:

analyze a further signal-to-noise ratio of a further commercial frequency-modulated radio signal; and

add the further signal-to-noise ratio to the signal quality vector, wherein the signal quality vector includes the further signal-to-noise ratio when the current location fingerprint is compared to the fingerprint database to obtain the current location.

5. The computer system of claim 4, wherein the computer-executable instructions cause the one or more processing units to:

analyze a further multipath indicator of a further commercial frequency- modulated radio signal; and

add the further multipath indicator to the another signal quality vector, wherein the another signal quality vector includes the further multipath indicator when the current location fingerprint is compared to the fingerprint database to obtain the current location.

6. The computer system of claim 1, wherein the computer-executable instructions cause the one or more processing units to:

find a matching fingerprint in the fingerprint database that is a closest match with the current location fingerprint to obtain the current location.

7. The computer system of claim 6, wherein the computer-executable instructions cause the one or more processing units to:

designate a corresponding location represented by the matching fingerprint as the current location.

8. The computer system of claim 1, wherein the computer-executable instructions cause the one or more processing units to:

update the fingerprint database with the current location fingerprint including the signal quality vector and the another signal quality vector.

9. A method implemented by at least one computer processing unit for performing localization of a mobile device within an indoor structure, the method comprising:

obtaining a plurality of commercial frequency-modulated radio signals that are received within the indoor structure,

generating a first signal quality vector comprising signal-to-noise ratios of the plurality of commercial frequency-modulated radio signals;

adding the first signal quality vector to a current location fingerprint of the mobile device;

analyzing frequency offset indicators of the plurality of commercial frequency-modulated radio signals;

generating a second signal quality vector comprising the frequency offset indicators of the plurality of commercial frequency-modulated radio signals;

adding the second signal quality vector to the current location fingerprint of the mobile device; and

comparing the current location fingerprint comprising the first signal quality vector and the second signal quality vector to a fingerprint database to find a current location of the mobile device within the indoor structure.

10. The method of claim 9, further comprising:

analyzing received signal strengths of the plurality of commercial frequency-modulated radio signals;

generating a third signal quality vector comprising the received signal strengths of the plurality of commercial frequency-modulated radio signals; and

adding the third signal quality vector to the current location fingerprint, wherein the current location fingerprint also includes the third signal quality vector when compared to the fingerprint database to find the current location.

11. The method of claim 9, further comprising:

analyzing multipath indicators of the plurality of commercial frequency-modulated radio signals;

generating a third signal quality vector comprising the multipath indicators of the plurality of commercial frequency-modulated radio signals; and

adding the third signal quality vector to the current location fingerprint, wherein the current location fingerprint also includes the third signal quality vector when compared to the fingerprint database to find the current location.

12. The method of claim 9, further comprising finding a matching fingerprint in the fingerprint database that matches the current location fingerprint to find the current location.

13. The method of claim 12, further comprising designating a particular location corresponding to the matching fingerprint in the fingerprint database as the current location of the mobile device within the indoor structure.

14. The method of claim 13, further comprising updating the fingerprint database with the current location fingerprint comprising the first signal quality vector and the second signal quality vector such that the current location is associated with the current location fingerprint in the fingerprint database.

15. The method of claim 9, further comprising populating the fingerprint database by recording signal quality metrics at various locations within the indoor structure and associating the signal quality metrics with the various locations as corresponding fingerprints of the various locations.

16. A mobile device comprising:

one or more processing units; and

one or more computer storage media storing computer-executable instructions which, when executed by the one or more processing units, cause the one or more processing units to;

receive a commercial frequency-modulated radio signal on the mobile device;

receive a locally-generated radio signal on the mobile device;

analyze the commercial frequency-modulated radio signal and the locally-generated radio signal using signal quality metrics, the signal quality metrics including a signal-to-noise ratio metric representing a signal-to-noise ratio of the commercial frequency-modulated radio signal and another signal-to-noise ratio of the locally-generated radio signal;

generate signal quality vectors from the signal quality metrics, the signal quality vectors comprising an individual signal quality vector that includes the signal-to-noise ratio of the commercial frequency-modulated radio signal and another individual signal quality vector that includes the another signal-to-noise ratio of the locally-generated radio signal;

add the signal quality vectors to a current location fingerprint of the mobile device; and

find a current location of the mobile device within a building using the current location fingerprint.

17. The mobile device of claim 16, wherein the computer-executable instructions cause the one or more processing units to:

analyze another commercial frequency-modulated radio signal to determine another signal-to-noise ratio of the another commercial frequency-modulated radio signal; and

add the another signal-to-noise ratio to the individual signal quality vector and the current location fingerprint to find the current location of the mobile device.

18. The mobile device of claim 17, wherein the locally-generated radio signal comprises a WiFi®

radio signal, a Bluetooth®

radio signal, or another frequency-modulated radio signal.

19. The mobile device of claim 18, wherein the computer-executable instructions cause the one or more processing units to:

compare the current location fingerprint to a fingerprint database to find a matching fingerprint that matches with the current location fingerprint; and

designate a corresponding location associated with the matching fingerprint as the current location of the mobile device within the building.

20. The mobile device of claim 19, wherein, of all fingerprints in the fingerprint database, the matching fingerprint most closely matches the current location fingerprint.