Spatio-diversity estimate of a system-dependent wideband directional channel

In this paper, we show that the effective multipath angle spread exhibits dependencies on both signal line-source distribution and operating frequency. As a result, the spatio-diversity gain is calculated through the integration of a continuous density function defined on the entire signal space. Starting with a simple single-cluster-single-bounce channel and perfect receiver conditions, the mathematical framework is then extended to more general situations, i.e., channels with multiple reradiation processes and scattering clusters. Numerical results show that the conventional diversity estimate for directional systems may lead to systematic prediction error of the achievable diversity gains.