Differential Space-Time Modulation for Wideband Wireless Networks

摘要

This project investigated differential modulation for broadband wireless communication systems equipped with multiple transmit antennas operating in frequency-selective channels. The objective was to provide full spatio-spectral diversity and coding gain at affordable decoding complexity without the burden of estimating the underlying space-time frequency-selective channel. The authors have developed two differential space-time modulation schemes tailored to frequency-selective channels. These schemes offer different trade-offs in dealing with time-selective versus frequency-selective fading channels. When applied along with a full-diversity spectral code, these schemes achieve full spatio-spectral diversity and significant coding gain. They also have examined the code design problem for the system under consideration, and obtained optimum code design criteria. For practical spectral encoding, they have developed a class of minimum-length full-diversity codes, referred to as linear constellation decimation (LCD) codes, which offer significant coding gain at modest decoding complexity. They also have developed a differential space-time modulation scheme using amplitude-phase shift keying (APSK) symbols, which are more efficient than conventional PSK-based differential space-time techniques.