A system and method for providing timing information to a wireless device
in a position determination system is disclosed. A wireless device
includes a reference signal receiver, a signal processor, a wireless
communications transceiver and a GPS receiver. The wireless device is
adapted to receive a reference signal, extract a snippet of the received
reference signal, determine a time of reception for the snippet and
transmit the snippet and time of reception to a position determination
entity as part of a request for GPS aiding information. The position
determination entity includes a timing source, a GPS memory for storing
GPS satellite information, a reference signal memory, a communications
interface, a signal processor and a control processor. The position
determination entity is adapted to continually receive and store a
reference signal along with an associated time of reception, and receive
the snippet and timestamp transmitted from the wireless device. The
position determination entity is further adapted to match the signal
snippet to a portion of the stored reference signal, determine a time
offset between the timestamp and the time of reception of the matched
portion of the stored reference signal, prepare aiding information for
the wireless device, synchronize the aiding information to the wireless
device using the time offset, and transmit the synchronized aiding
information to the wireless device. The wireless device is further
adapted to receive the aiding information, including timing information
to assist the wireless device in acquiring the GPS signals.