Satellite positioning receiver and proxy location system

摘要

To reduce power consumption in a user terminal, especially mobile devices, a system and method are introduced that use terrestrial beacons as a location proxy when satellite positioning signals are not available. The geographic locations of the terrestrial beacons need not be known to use the beacons as a proxy for a satellite positioning signals derived location.

主权项

1. A mobile device, comprising:
a first receiver, comprising a global navigation satellite system (GNSS) receiver configured to receive GNSS signals and to provide updates of GNSS location measurements over time; a second receiver configured to receive a terrestrial beacon signal; and a controller operatively coupled to the GNSS receiver and the second receiver; wherein the mobile device is configured to detect when GNSS signals are unavailable and, in response thereto, to use a received terrestrial beacon signal to determine whether a previous GNSS location measurement is valid, wherein the mobile device is configured to use the beacon as a proxy for a location derived from satellite positioning signals without knowing the geographic location of the terrestrial beacon; wherein the mobile device is further configured to perform the following steps:
employing the GNSS receiver to develop a first valid GNSS location including latitude, longitude, altitude, and timing;
in parallel, employing the second receiver to detect and identify one or more radio beacons in predefined transmission bands;storing the first valid GNSS location and a first list of beacons locally within the mobile device;entering the GNSS receiver into a low power sleep mode;upon determining that the GNSS receiver has failed to produce a valid current GNSS location fix, using the second receiver to produce a current beacon list of detectable, identifiable beacons;comparing the current beacon list to a prior beacon list associated in time with a last valid GNSS location update; andupon determining the presence of a limited-range beacon in both the current and prior beacon lists, reusing a previously obtained valid GNSS location as the current location of the device, and determining an error radius based on the type of limited-range beacon in both the current and prior beacon lists; and wherein the mobile device is further configured to passively use received beacon signals from multiple beacons as a proxy for a high accuracy GNSS location estimate by measuring and comparing the strengths of signals received from neighboring beacons during periodic sampling events.