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Originally Posted by stonent
I hope it refreshes if I call 911.
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Its pretty irrelevant if it refreshes or not...
A-GPS requires precise time to perform satellite signal processing. It can utilize precise time from a synchronized network (which provides optimized TTFF and sensitivity), or derive it on either a synchronized or an asynchronous network from aiding data received from the Location Server. A-GPS operates on any air interface network, synchronized or not, without requiring any costly equipment to derive time, and will operate with enhanced efficiency and performance on precisely synchronized networks.
What makes Assisted-GPS work so well is that the wireless network, using its own GPS receivers, as well as an estimate of the handset’s location down to cell/sector, can predict with great accuracy the GPS signal the handset will receive and send that information to the handset. With this assistance the size of the search space is greatly reduced and the time-to-first-fix (TTFF) shortened from minutes to seconds.