Association for Computing Machinery
The Global Positioning System (GPS) is one of the most pervasive wireless technologies. It is incorporated in more than one billion Smartphones world-wide, and embedded in a wide variety of devices, including personal navigation systems, sensors, digital cameras, and even under-the-skin bio-chips. The key functionality of a GPS receiver is to calculate a position, called a fix. Computing a fix involves locking on the GPS satellite signals and decoding satellite orbit and time data. Most GPS receivers, however, are embedded with some other radio (e.g., WiFi, cellular, or ZigBee) and, hence, can download the content of the GPS signal from Assisted GPS (A-GPS) servers instead of decoding it from the satellite signals.