Modelling for radiowave propagation in city microcells

摘要

Diffraction is one of the key radiowave propagation mechanisms inncity microcell environments. This is especially true for radiowavenpropagation into side roads and roads parallel to the main coverage areanwhere line-of-sight paths do not normally exist. Field experiments havenshown that at 900 MHz the signal level drops by 20 dB when a mobile unitnturned into a side road. The author explains the mechanism of radiowavenpropagation in typical city microcell environments. With this knowledge,nthe observed signal variation can be characterised by either using anrelatively complex model based on geometrical optics and the geometricalntheory of diffraction or a simple model based on piecewise linearnregression. The former modelling approach enables more accuratenprediction of the signal levels especially along side roads, while thenlatter reduces computation significantly and is more suitable for largenscale cellular radio system performance simulations