Differential unitary space-time modulation with multiple-symbol detection

Abstract

This work describes the multiple symbol detection (MSD) of differential unitary space-time modulation (DUSTM) for fading channels. The performance of the previously proposed conventional differential detection (DD) receiver is acceptable only when channels vary very slowly. It is shown that conventional differential detection (DD) suffers from a considerable loss in performance and is not suitable for moderately fast fading channels. In order to fully utilize the capabilities of the transmit diversity of the DUSTM, we adopted multiple-symbol maximum likelihood (ML) decision metric for DUSTM under fading channels. Multiplesymbol detection (MSD) of differential unitary space-time modulation (DUSTM) uses maximum likelihood sequence detection of μ symbols to achieve a performance gain over conventional 2 symbol differential detection (DD). To further improve the performance of DUSTM system, we consider the newly suggested trellis-coded differential unitary space-time modulation (TC-DUSTM), which combines trellis encoding and USTM mapping together to enhance performance. Using results from MSD, an additive symbol by symbol metric is developed for non-coherent detection of trellis-coded DUSTM (TC-DUSTM). Simulation results confirm that the proposed receiver enhances the performance, while computational complexity increases only linearly with the size of μ.