Propagation models for Heterogeneous Networks

In this paper, the different categories of propagation modeling are introduced, namely empirical, semi-empirical and deterministic. Semi-empirical models can provide a first insight into the coverage of each layer (macro-cell, outdoor and indoor small-cells) but present many limitations for HetNet coverage prediction. On the other hand, deterministic ray-based models provide high accuracy for all configurations and radio links met in HetNet. Small and large propagation ranges are all addressed in a coherent way, thus cross-correlation between various links is inherently finely estimated resulting in an accurate HetNet coverage prediction. Besides, variations of signal levels at different reception floors can be reproduced by the construction of precise 3D ray paths. Thereby, coverage and system simulation tools can be fed with realistic scenarios and accurate 3D path loss predictions to investigate the impact of small-cells, to define a deployment strategy and finally to design and optimize HetNets.