GPS signal Rician fading model for precise navigation in urban environment

Abstract

Global Positioning System (GPS) usage is not limited to the aircraft en-route navigation and missile guidance where the user receives the satellite signals from the open sky. Currently, GPS has become an essential utility in the car navigation, mobile phones, surveying and aircraft landing applications. The received signal strength of a GPS satellite at a given location on or near the earth surface can be predicted by analyzing the propagation characteristics of the channel with an appropriate propagation model. The signal propagation characteristics particularly the short term variations severely affect the quality, availability and continuity of the system. The short term propagation characteristics of GPS signal is modeled and analyzed in this paper. Short term variations are mainly due to multipath reflections and Doppler shift which degrades the quality of received signal particularly in urban environments. The variation of signal quality with respect to user velocity is observed using Rician fading model.