Modeling the GNSS Rural Radio Channel: Wave Propagation Effects caused by Trees and Alleys

Among the various physical influencing factors with the potential to degrade the overall performance of a global navigation satellite system (GNSS), the propagation mechanisms in the channel between a satellite and the mobile receiver play a central role. Especially multipath propagation and signal shadowing may cause high ranging, and hence positioning, errors in current receivers. Although new signals and ranging codes with higher bandwidths become available, the principal issue of multipath propagation inherent to the time-varying GNSS radio channel cannot fully be eliminated. Detailed analysis and knowledge of the radio channel characteristics under realistic conditions are essential to identify and eventually be able to mitigate these disturbances. The goal of the presented work is to understand the propagation conditions in rural settings for vehicular landmobile users. As a contribution to the design of a comprehensive GNSS rural channel model, the effects caused by single trees are investigated. Even though individual trees spaced afar from each other along a road do not cause much harm to the smoothing tracking algorithm of a delaylock-loop (DLL) of GNSS receiver, an alley of tree can profoundly impact the tracking performance of the DLL.