The use of measurement data to analyse the performance of rooftop diffraction and foliage loss algorithms in a 3-D integrated urban/rural propagation model

This paper describes a 3-D integrated propagation model, which considers propagation effects in both urban and rural environments. It uses a variable resolution digital terrain map (DTM) as well as building and foliage databases. Scattering off terrain pixels and building walls is modelled, as are off-axis terrain and rooftop diffraction contributions. The scattered power is estimated from radar cross-section analysis of the illuminated pixels and walls. The effects of foliage attenuation are also fully considered. The model predicts signal strength and time dispersion and provides fading and arrival angle information for the propagation channel. Narrowband measurements in both urban and rural areas show very good agreement with the predicted results. The accuracy of different foliage-loss and diffraction-loss models has been assessed, with the ITU-R foliage-loss model and the UTD model giving the best results. It is shown that large errors can result if the effects of foliage are ignored in the modelling process.