Aspects of global positioning system (GPS) technology and cellular technology are combined in order to provide an effective and efficient position location system. In a first aspect of the invention, a cellular network is utilized to collect differential GPS error correction data, which is forwarded...http://www.google.ca/patents/US5982324?utm_source=gb-gplus-sharePatent US5982324 - Combining GPS with TOA/TDOA of cellular signals to locate terminal
