A-GPS stands for Assisted Global Positioning System. It enhances the performance of a basic GPS’s location time and accuracy. Compared with regular GPS systems, A-GPS provides much faster positioning even when GPS signal conditions are weak.
A-GPS can locate a moving object within 5 yards in most cases, depending on the signal strength from satellites and cell towers.
A-GPS takes less power (saving battery life) and time to acquire satellite and cell tower signals and finds the user quicker. Under stand-alone GPS operation, a GPS receiver typically needs more than 30 seconds to receive the satellite position data and other satellite information required to compute a position. In weak signal areas such as urban canyons, building interiors or locations surrounded by tall trees, where the receiver has limited or no direct access to the open sky, determining a positioning can take much longer.