Some Extensions to the Statistical Analysis of Space Diversity Wireless Communication Systems

Abstract

There has been enormous interest over the last 2 decades in various diversity schemes to combat the effects of multipath and shadow fading in digital mobile radio systems. Space diversity techniques, possibly implemented by adaptive antenna arrays, have become generally accepted as attractive options in this field. This area has recently become extremely topical with the explosion of interest in transmit diversity to supplement receive diversity, giving rise to multiple-input multiple-output (MIMO) systems. The goal of this thesis is to contribute some extensions to the statistical analysis of space diversity wireless communication systems (including MIMO systems). The main extensions include the following Maximal ratio combining (MRC): here we extend the analysis of MRC systems with multiple interferers in flat Rayleigh fading to cover arbitrary numbers of branches and interferers with any given powers. In particular we develop the exact distribution of the signal-to-interference-plus-noise ratio (SINR) and hence formulate exact bit error rate (BER) formulae for various modulations. Hybrid selection/Maximal-ratio combining (H-S/MRC): here we extend the analysis of general diversity combining in Rayleigh fading to a more general gamma fading channel. In particular we develop exact analytic results for the output signal-to-noise ratio (SNR) of H-S/MRC in gamma fading. Linear minimise mean square error (MMSE) combining: here we extend the analysis of MMSE systems from space diversity to a more complex space-time diversity. Macrodiversity combining: here we apply known analysis methods for microdiversity systems to macrodiversity systems by constructing "equivalent" microdiversity systems. MIMO systems: here we extend some analyses of single input multiple output (SIMO) systems to a MIMO system. An exact closed form expression for the mean BER of an ideal M-branch MMSE diversity combiner operating in a MIMO system with T transmit sources, N co-channel interferers and additive noise is derived. Power models: here we look at the issue of sensible scenarios for interferer powers. The analysis of most wireless systems depends on a knowledge of, or a model for these powers. We show that a simple model can be used in a variety of settings for providing reasonable sets of power values.