Mitigating 3G interferrence to GPS due to coexistence in 3G handset

Abstract

Co existence of Global Positioning System services (GPS) with cellular and other services and features in a mobile handset presents challenges to GPS performance. Particularly challenging is the over the air (OTA) interface to the GPS receiver that results from carriers like the Global System for Mobile (GSM) and Wideband Code Division Multiple Access (WCDMA) where the transmit (TX) section of the latter could interfere with the performance of the GPS due to TX band noise injected into the GPS band. For the case of WCDMA, the problem is the out of band interference due to the TX wide band noise which has a spectrum that matches the GPS spectrum; both use spread spectrum technology to encode the data.