Space Division Multiple Access (SDMA) is one of the most promising methods in solving the capacity problem of wireless communication systems. In addition to creating more efficient SDMA algorithms it is vital to determine and understand the theoretical limit of performance improvement. The greatest challenge is extending Shannon’s channel capacity equation to cover the wireless channels that use spatial signal processing. This book defines formulas which can be used to evaluate the limit capacity of multipath wireless channels in a particular receiving region with size limitation. It also contains charts with optimum numbers of space subchannels and limit capacities related to radio channel parameters. The book also investigates stochastic models for 2-D and 3-D multipath random radio channels. The non-ray method for building a stochastic model, based on spherical harmonics, is presented here for the first time.