A method and system are specified to determine, provide, and exploit the precise time base relations between the distinct signal timings of the Global Positioning System (GPS) and a wireless communications system (WCS) for which the internal WCS downlink time base standards are not inherently synchronized to GPS timing. These downlink signal synchronization facilities are particularly beneficial for a wireless location system (WLS) and related methods and subsystems that provide mobile-station location determination through the exploitation of the time base synchronization information, e.g., to assist a GPS-equipped mobile station in determining its GPS-derived measurements with enhanced efficiency and accuracy.