Assisted GPS

Please note that the content of this book primarily consists of articles
available from Wikipedia or other free sources online. Assisted GPS,
generally abbreviated as A-GPS, is a system which can improve the
startup performance of a GPS satellite-based positioning system. It is
used extensively with GPS-capable cellular phones as its development was
accelerated by the U.S. FCC's 911 mandate making the location of a cell
phone available to emergency call dispatchers.