Gps with aiding from ad-hoc peer-to-peer bluetooth networks

Abstract

The present invention is related to location positioning systems, and more particularly, to a method and apparatus for providing an update of ephemeris information. According to one aspect, GPS enabled devices in the signal unavailable area monitors the state of its ephemeris data and time information. When the ephemeris data and time information become out of date, the GPS enable device uses an ad hoc Bluetooth network to retrieve ephemeris data and time information from another GPS enabled device with more current data. According to further aspects, a map of a deep hole region in which GPS and other cellular signals are not available, is generated to enable power reduction and cost saving measures.

What is claimed is: 
     
         1 . A method for generating a deep hole map comprising:
 detecting a signal strength of at least one mobile Global Positioning System (GPS) device;   comparing the detected signal strength of the at least one mobile GPS device to a predetermined signal strength threshold value;   determining a last known position for the at least one mobile GPS device when the signal strength of at least one mobile GPS device is below the predetermined signal strength threshold value;   determining a first fix position for the at least one mobile GPS device when the detected signal strength returns to a value above the predetermined threshold value; and   transmitting the last known position and the first fix position to a crowd-sourcing server for use in generating the deep hole map.   
     
     
         2 . A method of refreshing navigational data comprising:
 generating a deep hole map;   determining a position of a mobile Global Positioning System (GPS) device;   determining a proximity to a deep hole based on the determined position of the mobile GPS device and the generated deep hole map;   comparing the determined deep hole proximity to a proximity threshold; and   refreshing the navigational data when the mobile GPS device is less than or equal to the to the proximity threshold value.   
     
     
         3 . A method according to  claim 2 , wherein the navigational data includes ephemeris data. 
     
     
         4 . A method according to  claim 2 , wherein the navigational data includes time sync data.