Propagation Prediction Models

To implement a mobile radio system, wave propagation models are necessary to determine propagation characteristics for any arbitrary installation. The predictions are required for a proper coverage planning, the determination of multipath effects as well as for interference and cell calculations, which are the basis for the high-level network planning process. In a GSM/DCS-system the high-level network planning process includes, e.g., frequency assignment and the determination of the BSS (base station subsystem) parameter set. Similar planning tasks will exist also in third generation systems. The environments where these systems are intended to be installed, are stretching from in-house areas up to large rural areas. Hence wave propagation prediction methods are required covering the whole range of macro-, microand pico-cells including indoor scenarios and situations in special environments like tunnels and along railways. The phenomena which influence radio wave propagation can generally be described by four basic mechanisms: Reflection, penetration, diffraction, and scattering. For the practical prediction of propagation in a real environment these mechanisms must be described by approximations. This requires a three-stage modelling process: In the first step the real (analogue) terrain has to be digitised yielding digital terrain data. Therefore some interest in the COST 231 project has focused on the types, resolution and accuracy of digital terrain databases required for propagation modelling. The information includes terrain height information, land usage data, building shape and height information and building surface characteristics. Furthermore investigations have