Statistical Analysis of Indoor Multipath Channels Based on Ray Tracing Analysis

Indoor mobile radio communications have become an area of great interest as the push for the universal personal communication (UPC) environment becomes more intense. Although the basis of electromagnetic propagation is well known through application of Maxwell's equations, the relationship between propagation and building structures is not well defined. This situation arises as the application of Maxwell's equations to objects that are not simple structures becomes non-trivial as definition of appropriate boundary conditions becomes highly complex. Using a ray tracing model, this paper will show how such a model may be used to extract statistical information on a channel, and more significantly, how the propagation mechanisms underlying particular distributions observed in the practical environment can be identified and isolated. The model is a deterministic one based on the theory of images, with extensions to cover the effects of diffraction around corners. Results from the ray tracing model are presented in the form of standard two dimensional probability functions, and also in a three dimensional format. The latter is applicable to the multipath environment experienced in indoor communications as the wideband characteristics of the channel are not easily represented in a two dimensional format. The results show that the interaction between multipath components, in particular their phase relationships, form the basis of the probability distributions experienced in the practical environment. 1