Propagation prediction by ray-tracing or ray-launching generally assumes that reflections from buildings and other seemingly plane surfaces occur as specular reflections. Recent measurement results  have shown that in reality buildings and other objects can ause dispersion of the specular reflected component. This causes multiple rays to arrive at the receiver from the specular direction and in a small area around it. The angular dispersion of radiowaves are considered to be important for future radio systems (e.g. smart-ntennas, MIMO) and need to be incorporated in propagation prediction models in an efficient way The problem is addressed in several recent publications and methods are proposed that include diffuse scattering, which causes angular dispersion. Firstly, this paper gives a short introduction and a description of two recently proposed methods. Secondly, a proposal for a new approach is presented, in which the angular dispersion is determined directly at the receiving position using a stochastic effective roughness method.
|Title of host publication||Proceedings of Cost 2100 Pervasive Mobile & Ambient Wireless Communications, 4 - 6 June 2008, Trondheim, Norway|
|Publication status||Published - 2008|