A ray-based, millimetre wave urban propagation tool

In the UK, the 38 GHz frequency band is available for digital, fixed links. Commercial 2 and 4 Mbits/s equipment is available from several manufacturers. Allowing for rain fade system margins, path lengths are typically up to 10 km. One major application is providing the feeder links for PCN services. As the density of 38 GHz links increases, the problem of coordination will become more severe. An earlier investigation by Craig and Norbury (1993) showed that in urban locations, the effects of building scatter are likely to be the limiting factor on the frequency re-use possible. Statistical methods are of limited value for millimetric point-to-point links, since the siting of individual buildings can produce strong shielding or provide a source of high reflected field levels. In the urban environment, a planning tool for the siting of antenna, needs to be deterministic and based on a building database. This paper describes such a tool, based on three dimensional ray-tracing, developed at the Radio Communications Research Unit. The first part covers the principles of ray tracing and the way they have been implemented. Then, the features of the model are presented and eventually a short description of first validation measurements are made