Channel propagation study of SDMA schemes for wireless communications

A spatial signature is the response vector of a base station antenna array to a mobile terminal. In a typical wireless communication environment, mobile subscribers at different locations exhibit different spatial signatures. The exploitation of spatial diversity (or the difference of spatial signatures) is the basic idea of the Space-Division-Multiple-Access (SDMA) scheme, which can be used in wireless communications to mitigate the effect of multipath fading as well as to increase system capacity and communication quality via spatially selective reception/transmission at base stations.;This dissertation studies the vector channel propagation characteristics of the SDMA schemes by using a smart antenna testbed in various typical scenarios as well as experimental evaluation of smart antenna system performance for wireless communications. Extensive experimental results of spatial signature variations, diversity gain, mitigation of multipath fading obtained by using a smart antenna system and the experimental evaluation of the Signal-to-Interference Ratio (SIR) of two moving users by using different beamforming algorithms for downlink transmission in typical wireless scenarios are presented. Also presented in this dissertation is a subspace smoothing algorithm for finding the directions of arrival (DOAs) of multipath signals based on mobile terminal signals received at different time instances.