Modeling GNSS Signals in Urban Canyons using Visibility Graphs

This paper addresses the problem of modeling and simulating RF-signals captured by receivers of Global Navigation Satellite Systems (GNSS) in urban canyons. The presence of tall buildings in urban canyons often block lines of sight between receivers and GNSS satellites, and therefore signals reach the receivers indirectly, after bouncing off buildings. These multi-path and echo-only effects are the major causes for inaccurate location estimations in urban canyons. Simulators for GNSS are essential tools for properly testing positioning algorithms before production. We develop such a simulator utilizing a geometric framework that simulates the paths of the received RF-signals in urban regions. We define a visibility graph over the buildings, then introduce and implement several novel heuristics in order to improve the algorithm’s performance. We conduct a set of experiments to examine the effects of these heuristics on the simulation runtime. ∗This research was partially supported by the MatiMop program of the Israel Ministry of Industry and Trade iGalileo consortium.