Method and apparatus for optimizing GPS-based position location in presence of time varying frequency error

A method of optimizing GPS based position location in the presence of time-varying frequency error, comprising:

• determining a GPS doppler bias value including determining a CDMA code doppler bias value;
• centering a GPS doppler search window based on the GPS doppler bias value;
• adjusting for the GPS doppler bias value during GPS code phase measurement time propagation to common time;
• and
• adjusting for the CDMA code doppler bias value during AFLT code phase measurement time propagation to common time.

A method of optimizing GPS based position location in the presence of time-varying frequency error, comprising:

• determining a GPS doppler bias value;
• centering a GPS doppler search window based on the GPS doppler bias value;
• adjusting for the GPS doppler bias value during GPS code phase measurement time propagation to common time;
• storing a CDMA channel independent GPS doppler bias value in a cellular device memory;
• storing a calculated CDMA channel dependent GPS doppler and CDMA code doppler bias values, wherein the stored CDMA channel dependent CDMA code doppler bias value is used to propagate AFLT code phase measurements to common time;
• and
• utilizing the CDMA channel independent GPS doppler bias value and the CDMA channel dependent GPS doppler bias value to re-center the GPS doppler search window for all search modes.

A wireless communication device for optimizing GPS based position location in the presence of time varying frequency error, comprising:

• a receiver for receiving signals from a base station, the signals including an indication of the timing of a GPS satellite;
• a GPS receiver;
• and
• a control processor coupled to the receiver and to the GPS receiver, and configured to use the received timing of the GPS satellite to determine a GPS search window center in doppler to search for the satellite;
• wherein the GPS doppler search window center is determined by determining a total GPS doppler bias value and by centering the GPS doppler search window based on the total GPS doppler bias value, and wherein a CDMA channel dependent CDMA code doppler bias value is calculated and accounted for during time propagation of AFLT code phase measurements to common time prior to reporting the AFLT code phase measurements to a position determining entity (PDE) or using the AFLT code phase measurements in a wireless device position location engine.

A tangible data storage medium comprising executable data capable of causing a programmable device to perform the steps of:

• determining a GPS doppler search window center for searching for a global positioning system (GPS) satellite, including the steps of:
• determining a GPS doppler bias value including determining a CDMA code dopper bias value;
• and
• centering a GPS doppler search window based on the GPS doppler bias value;
• and
• accounting for GPS doppler and CDMA code doppler bias while propagating GPS pseudorange and AFLT pilot phase measurements, respectively, to common time.