Demodulation and Performance Analysis of Differential Unitary Space-Time Modulation in Time-Varying Rician Channels

Studies on differential unitary space-time modulation are mostly focused on Rayleigh fading channels. In this paper we present new analytic results for the maximum-likelihood demodulator (MLD) and the standard differential demodulator (SDD). The resulting expressions and bounds on the pairwise error probability shed light on the impact of various system parameters and are helpful towards a deeper understanding of the DUSTM in Rician channels. Additional analytic results are also derived for the constellation in the work of Tarokh and Jafarkhani (2000). Unlike in Rayleigh fading, the exact MLD can only be implemented approximately (Cui and Tellambura, 2006). The performance loss of practical demodulator such as the SDD and a prediction-based demodulator relative to the MLD are studied under different Rician fading environments.