 ceiving point or a given maximum number of interactions characteristics of diffuse scattering from typical buildings is reached. If successive runs over the same topology must facades is reported. The study demonstrated that diffuse be carried out, then most part of the computation is al- scattering is concentrated on Keller's cones corre- ready done and saved in a file. The model is shown to sponding to diffractions from horizontal and vertical perform very well in three different routes in the city of edges of external decorations and periodical structures Munich, which were considered in the COST 231 blind such as indentations, windows, etc. test: the mean error is of a fraction of dB and the standard A recent experimental investigation [DEFVG05], deviation of the error is of about 7 dB. however, showed that a single-lobe, continuous scattering A similar performance is achieved in indoor environ- pattern well describes the average scattering behaviour of ments. In [WZWH03] the same method as above is used typical building walls when observed from a distance. for outdoor prediction, then another BL model is used This is probably due to the fact that a considerable per- for enclosed spaces with a proper interface between the centage of power penetrates into the building, interacts two models enabling the computation of the transition with furniture and inner structures, and then comes out from an urban scenario to an indoor scenario and vice again in a chaotic way apparently without following versa, thus allowing an accurate computation of the field diffraction/reflection rules. strength or received power inside vehicles or buildings. In [BHHT04a], the authors used a sophisticated As a border for the interface, a polygonal cylinder in- 'synthesised array' method to determine intensity, angle cluding the whole indoor database is automatically de- and time of arrival of waves scattered from a brick termined. As an adequate way to handle the interface building wall with windows. The wall was illuminated between th