Precision of the estimation of area coverage by planning tools in cellular systems

Coverage prediction in modern cellular systems is usually performed with the aid of a planning tool, using a suitable elevation and terrain digital model (i.e., a database of heights and land usage) and algorithms that estimate basic path loss plus additional diffraction loss. These algorithms produce a mean field strength estimation on a pixel-by-pixel basis, and the tool can then compute the percentage of coverage of a given territory (e.g., national or regional). Because of errors by the field estimation algorithm, this number has an associated degree of uncertainty as well, which is calculated in this study. This is done starting from the statistical distribution of the estimation errors; based on an analysis of the nature of the estimation process, a statistical distribution for errors on a cell-by-cell and wide-area basis is then derived. Okumura-type estimation algorithms are considered in the study, tuned with the aid of measurements. Constant reference is made to field experience, since the measurements considered here and the knowledge of the capabilities and limits of planning tools derive from Omnitel's two-year monitoring experience in this area.