A Dynamic Visibility Algorithm for Ray Tracing in Outdoor Environments with Moving Transmitters and Scatterers

This paper presents an efficient technique to identify surfaces which are visible to a mobile transmitter in outdoor environments with moving scatterers. The presence of moving scatterers or a mobile transmitter in a propagation environment makes the radio channel modelling very challenging as visibility computations need to be repeatedly performed in a changing scenario. This makes the pre-processing overhead unfeasible for ray-tracing based propagation prediction models. The algorithm described in this paper first computes the static visibility table for the mobile transmitter assuming that the environment is static. Then the effects of moving scatterers are modelled to compute the so-called dynamic visibility table. Both the static and dynamic visibility tables are used along with information about the scatterers’ location to validate the rays arriving at the receiver. Validation results show a considerable reduction in run times.