Rain fade countermeasure prediction and performance for millimetre broadband fixed wireless communication systems

Broadband millimetre wave communications networks are envisaged to provide fast multimedia services in the home. Their main attraction lies in the large amount of spectrum that lies underutilised within the 20-50 GHz bands. This advantage comes with the increased susceptibility of these systems to atmospheric influences. Rain attenuation within this band is the major factor that reduces system availability. Novel fade countermeasure techniques are required to improve system availability. Route diversity is one such technique. In a route diversity link configuration where two links have an angular separation, communication is switched from the reference link to the diversity link in the event of a fade. Due to the spatial and temporal variability of rainfall, there is some probability that the fade experienced on the diversity link will be less than on the reference link. We present diversity-modelling studies which have facilitated the development of a rain diversity model taking into account the temporal and spatial variation of rain and configuration of the links. Link measurement studies have also confirmed that the diversity scheme can significantly improve link availability during a rain fade.