Method and apparatus for identifying wireless transmitters

• US 20070025245A1
• Filed: 07/24/2006
• Published: 02/01/2007
• Est. Priority Date: 07/22/2005
• Status: Active Grant

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Corr, Michael, Manseau, David, Watt, David, Porras, Phillip, Dawson, Steven, Marcotullio, John
• Granted Patent: US 8,249,028 B2
• Time in Patent Office: Days
• US Class Current: 370/229
• CPC Class Codes: H04L 63/0236 Filtering by address, protocol, port number or service, e.g. IP-address or URL
• CPC Class Codes: H04W 99/00 Subject matter not provided for in other groups of this subclass

Abstract

In one embodiment, the present invention is a method and apparatus for identifying wireless transmitters. In one embodiment, a method for identifying a transmitter in a wireless computing network includes extracting one or more radio frequency signal characteristics from a communication from the transmitter and generating a fingerprint of the transmitter in accordance at least one of the extracted radio frequency signal characteristics.

Claims

1. A method for identifying a transmitter in a wireless computing network, the method comprising:

extracting one or more radio frequency signal characteristics from a communication from the transmitter; and

generating a fingerprint of the transmitter in accordance with at least one of the extracted radio frequency signal characteristics.

2. The method of claim 1, wherein the one or more radio frequency signal characteristics are extracted from at least one data link layer frame of the communication.

3. The method of claim 1, wherein the one or more extracted radio frequency signal characteristics include characteristics that are at least one of:

device-unique, model-unique or session-unique.

4. The method of claim 3, wherein the device-unique characteristics include at least one of:

carrier signal frequency, clock offset and jitter, phase noise and sideband characteristics.

5. The method of claim 3, wherein the model-unique characteristics include at least one of:

signal drift, a shift recovery characteristic, signal constellation stability, signal amplitude rise time or active gain control.

6. The method of claim 3, wherein the session-unique characteristics include at least one of:

signal strength intensity, angle or arrival and angle/delay spread.

7. The method of claim 1, wherein said generating comprises:

constructing an expectation of radio frequency signal characteristics of one or more transmission events associated with the transmitter.

8. The method of claim 1, wherein the fingerprint further comprises a tolerance indicative of a permissible deviation from a stored fingerprint.

9. The method of claim 1, wherein the generating further comprises:

estimating a location of the transmitter in accordance with the one or more extracted radio frequency signal characteristics.

10. The method of claim 1, wherein the generating comprises:

generating a full fingerprint for initial authentication of the transmitter to the wireless computing network, where the full fingerprint is generated in accordance with all of the one or more extracted radio frequency signal characteristics;

generating a light-weight fingerprint for each of one or more communications received from the transmitter after authentication, where the light-weight fingerprint is generated in accordance with a subset of the one or more extracted radio frequency signal characteristics; and

determining how to treat a given one of the one or more communications in accordance with a light-weight fingerprint associated with the given one of the one or more communications.

11. The method of claim 10, wherein the subset includes at least one of:

angle of arrival, signal strength or center frequency error.

12. The method of claim 1, further comprising:

storing the fingerprint in a database.

13. The method of claim 12, wherein a database entry for the fingerprint further comprises a corporate asset identifier.

14. The method of claim 1, wherein the one or more extracted radio frequency signal characteristics include at least one of:

one or more turn-on section characteristics of the communication or one or more turn-off section characteristics of the communication.

15. The method of claim 14, wherein the one or more extracted radio frequency signal characteristics include at least one of:

one or more Legendre polynomial coefficients generated from a log-magnitude power within the turn-on section, one or more Legendre polynomial coefficients generated from a log-magnitude power within the turn-off section, turn-on step duration, turn-off step duration, turn-on time placement, turn-off time placement, turn-on normalized power level or turn-off normalized power level.

16. The method of claim 1, wherein the extracted radio frequency signal characteristics include at least one of:

a data rate of an orthogonal frequency-division multiplexing frame of the communication, a number of symbols in a frame of the communication, common pilot error, error vector magnitude, pilot subcarrier error vector magnitude, center frequency error, IQ offset, quadrature skew error, IQ gain imbalance, synchronization correlation or symbol clock frequency error.

17. The method of claim 1, wherein the wireless computing network is an Institute of Electrical and Electronics Engineers 802.11 wireless computing network.

18. A computer readable medium containing an executable program for identifying a transmitter in a wireless computing network, where the program performs the steps of:

extracting one or more radio frequency signal characteristics from a communication from the transmitter; and

generating a fingerprint of the transmitter in accordance with at least one of the extracted radio frequency signal characteristics.

19. The computer readable medium of claim 18, wherein the one or more radio frequency signal characteristics are extracted from at least one data link layer frame of the communication.

20. The computer readable medium of claim 18, wherein the one or more extracted radio frequency signal characteristics include characteristics that are at least one of:

device-unique, model-unique or session-unique.

21. The computer readable medium of claim 20, wherein the device-unique characteristics include at least one of:

carrier signal frequency, clock offset and jitter, phase noise and sideband characteristics.

22. The computer readable medium of claim 20, wherein the model-unique characteristics include at least one of:

signal drift, a shift recovery characteristic, signal constellation stability, signal amplitude rise time or active gain control.

23. The computer readable medium of claim 20, wherein the session-unique characteristics include at least one of:

signal strength intensity, angle or arrival and angle/delay spread.

24. The computer readable medium of claim 18, wherein said generating comprises:

constructing an expectation of radio frequency signal characteristics of one or more transmission events associated with the transmitter.

25. The computer readable medium of claim 18, wherein the fingerprint further comprises a tolerance indicative of a permissible deviation from a stored fingerprint.

26. The computer readable medium of claim 18, wherein the generating further comprises:

estimating a location of the transmitter in accordance with the one or more extracted radio frequency signal characteristics.

27. The computer readable medium of claim 18, wherein the generating comprises:

generating a full fingerprint for initial authentication of the transmitter to the wireless computing network, where the full fingerprint is generated in accordance with all of the one or more extracted radio frequency signal characteristics;

generating a light-weight fingerprint for each of one or more communications received from the transmitter after authentication, where the light-weight fingerprint is generated in accordance with a subset of the one or more extracted radio frequency signal characteristics; and

determining how to treat a given one of the one or more communications in accordance with a light-weight fingerprint associated with the given one of the one or more communications.

28. The computer readable medium of claim 27, wherein the subset includes at least one of:

angle of arrival, signal strength or center frequency error.

29. The computer readable medium of claim 18, further comprising:

storing the fingerprint in a database.

30. The computer readable medium of claim 29, wherein a database entry for the fingerprint further comprises a corporate asset identifier.

31. The computer readable medium of claim 18, wherein the one or more extracted radio frequency signal characteristics include at least one of:

one or more turn-on section characteristics of the communication or one or more turn-off section characteristics of the communication.

32. The computer readable medium of claim 31, wherein the one or more extracted radio frequency signal characteristics include at least one of:

one or more Legendre polynomial coefficients generated from a log-magnitude power within the turn-on section, one or more Legendre polynomial coefficients generated from a log-magnitude power within the turn-off section, turn-on step duration, turn-off step duration, turn-on time placement, turn-off time placement, turn-on normalized power level or turn-off normalized power level.

33. The computer readable medium of claim 18, wherein the extracted radio frequency signal characteristics include at least one of:

a data rate of an orthogonal frequency-division multiplexing frame of the communication, a number of symbols in a frame of the communication, common pilot error, error vector magnitude, pilot subcarrier error vector magnitude, center frequency error, IQ offset, quadrature skew error, IQ gain imbalance, synchronization correlation or symbol clock frequency error.

34. The computer readable medium of claim 18, wherein the wireless computing network is an Institute of Electrical and Electronics Engineers 802.11 wireless computing network.

35. A system for identifying a transmitter in a wireless computing network, comprising:

means for extracting one or more radio frequency signal characteristics from a communication from the transmitter; and

means for generating a fingerprint of the transmitter in accordance with at least one of the extracted radio frequency signal characteristics.

36. The system of claim 35, wherein the wireless computing network is an Institute of Electrical and Electronics Engineers 802.11 wireless computing network.

37. The system of claim 35, wherein the means for extracting comprises a vector signal analyzer.