Geometrical channel models for space-time systems

Abstract

Based on the unified concept of space-time system field theory, a general space-time channel model can be constructed from the statistics of the space-time system field function (S-TSFF) for an arbitrary medium. This statistical characterization of the medium (channel) can be expressed in terms of the space-time correlation function, or, equivalently, the space-time power spectral density of the S-TSFF. The space-time correlation function of the S-TSFF generalizes the concept of the mutual coherence function (MCF) for a random electric field to an arbitrary space-time field. There are three different geometrical channel models depending on the choice of the coordinate systems, e.g. rectangular, cylindrical, and spherical. Using the notions of channel correlation time and correlation distance— i.e. doppler spread and delay spread—various geometrical tap-delay channel models are derived. From a system point of view, the space-time correlation parameters can be interpreted as a measure of the spatial and tem...