RF Network Planning Issues
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 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-, micro- and 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.
The practice of determination of radio channel characteristics in cellular UHF land mobile radio applications is dominated by surface scattering considerations. Before any propagation (scattering) computation can be performed, these surfaces must be characterized. The development of propagation prediction techniques for the estimation of channel characteristics is a cyclic, three stage process: the first step is to abstract the simplest surface model which is considered to be likely to yield sufficiently accurate predictions; the second stage is concerned with finding efficient (often approximate or numerical) solutions to the scattering problems thus posed; and the third stage is to verify the choice made in the first stage. In each of these stages one must make use of geographical information.