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

Abstract

Among the various physical influencing factors with the potential to degrade the overall performance of a global navigation satellite system (GNSS), the behavior of the radio wave propagation channel occupies doubtlessly a central role. Especially multipath propagation and signal shadowing cause high ranging and hence positioning errors in current receivers. Although new signals and ranging codes with higher bandwidths become available, the principal issues 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 such disturbances. The goal of the presented work is to establish an understanding of the propagation conditions in rural settings for vehicular land-mobile users. As a contribution to a comprehensive GNSS rural channel model, the effects caused by single trees are examined. Even though individual trees spaced afar from each other along a road do not evoke much harm to the smoothing tracking algorithm of a delay-lock-loop (DLL), an alley can profoundly impact a GNSS receiver's tracking performance.