Performance analysis of time hopping and direct sequence UWB space-time systems
In this paper, we analyze the performance of ultra-wideband (UWB) multiple-input multiple-output (MIMO) systems employing various modulation and multiple access schemes, including time hopping (TH) binary pulse position modulation (BPPM), TH binary phase shift keying (BPSK), and direct sequence (DS) BPSK. We quantify the performance merits of UWB space-time (ST) systems regardless of the specific coding technique. We introduce a framework that enables us to compare UWB-MIMO systems with conventional UWB single-antenna systems in terms of diversity and coding gains. We show that the combination of ST coding and Rake architecture is capable of exploiting spatial diversity as well as multipath diversity, richly inherent in UWB environments. We find the upper bound on the average pairwise error probability (PEP) under the hypothesis of quasi-static Nakagami-m frequency selective fading channels. Finally, simulation results are presented to support the theoretical analysis.