CONTROLLING A GPS RECEIVER BY DETECTING MOTION BASED ON RADIOFREQUENCY SIGNAL TRACES
First Claim
1. A method, performed by a wireless communications device, of controlling operation of a receiver configured to receive signals from a satellite-based navigation-signal broadcast system, the method comprising:
- receiving radiofrequency signal traces from one or more base station towers;
applying first and second classifiers to determine from the signal traces whether the wireless communications device is moving or stationary, wherein the second classifier comprises a greater number of signal features than the first classifier;
deactivating the receiver when the wireless communications device is determined to be stationary; and
reactivating the receiver when the wireless communications device is determined to be moving.
4 Assignments
0 Petitions
Accused Products
Abstract
Operation of a satellite-based navigation-signal broadcast system receiver, such as a GPS receiver, on a wireless communications device is controlled by determining whether the device is stationary or in motion. Motion determination is accomplished by analyzing radiofrequency signal traces, e.g. GSM signal traces, received from one or more nearby base stations. A three-tiered analysis provides a progressively more accurate determination as to whether the device is moving or stationary while providing, in certain instances, a more rapid determination than prior-art techniques. When the device is determined to be stationary, the GPS receiver can be deactivated. When the device is determined to be moving, the receiver can be reactivated.
17 Citations
19 Claims
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1. A method, performed by a wireless communications device, of controlling operation of a receiver configured to receive signals from a satellite-based navigation-signal broadcast system, the method comprising:
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receiving radiofrequency signal traces from one or more base station towers; applying first and second classifiers to determine from the signal traces whether the wireless communications device is moving or stationary, wherein the second classifier comprises a greater number of signal features than the first classifier; deactivating the receiver when the wireless communications device is determined to be stationary; and reactivating the receiver when the wireless communications device is determined to be moving. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A machine-readable storage medium comprising instructions in code which, when loaded into memory and executed on a processor of a wireless communications device, controls operation of a receiver configured to receive signals from a satellite-based navigation-signal broadcast system by:
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receiving radiofrequency signal traces from one or more base station towers; applying first and second classifiers to determine from the signal traces whether the wireless communications device is moving or stationary, wherein the second classifier comprises a greater number of signal features than the first classifier; deactivating the receiver when the wireless communications device is determined to be stationary; and reactivating the receiver when the wireless communications device is determined to be moving.
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- 10. The machine-readable storage medium as claimed in claim further comprising code for applying a third classifier, wherein the third classifier comprises a greater number of signal features than the second classifier.
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12. A wireless communications device comprising:
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a receiver for determining a current location of the device from a satellite-based navigation-signal broadcast system; a radiofrequency transceiver for receiving signal traces from one or more nearby base stations; and a processor operatively coupled to memory for applying first and second classifiers to determine from the signal traces whether the wireless communications device is moving or stationary, wherein the second classifier comprises a greater number of signal features than the first classifier, the processor deactivating the receiver when the device is determined to be stationary and reactivating the receiver when the device is determined to be moving. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method of training classifiers for determining whether a wireless communications device is moving or stationary based on radiofrequency signal traces received from nearby base stations, the method comprising:
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identifying a plurality of signal features for analyzing signal traces; receiving radiofrequency signal traces from one or more base station towers; receiving accelerometer readings indicating whether the device is moving or stationary; and training first and second classifiers by determining coefficients of logistic functions, the first and second classifiers providing a progressively more accurate determination as to whether the wireless communications device is moving or stationary. - View Dependent Claims (19)
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Specification