Indian Journal of Science and Technology

Abstract

Even with the presence of complex entities in their code structure, Conventional Quasi-Orthogonal Space-Time Block Codes (QO-STBC) can accomplish the goal of obtaining full rate but with the drawback of higher decoding complexity and less diversity gain. The logic behind more complications while decoding quasi-orthogonal codes is due to the existence of non-diagonal interference terms in the grammian matrix. In the case of conventional QO-STBC, there is a presence of pair wise decoding rather than the individual symbol decoding at the receiver end; these non-diagonal terms are responsible for the creation of interference from the neighboring elements which makes the system more complex. To overcome these drawbacks, a new paradigm is introduced for three transmit antennas which can bring out improved diversity gain and less decoding complexity by making a diagonal detection matrix. Analysis has been done for conventional QO-STBC3, RARQOSTBC3 and Taha3 scheme for three transmit antenna and different receive antenna configurations. Study over different channels and simulation results for the different order of PSK modulation shows that the RAR-QOSTBC3 outperforms the conventional QO-STBC3 and Taha3 scheme regarding bit error rate.

Keywords: BER, Linear Zero-Forcing Decoder, M-PSK, QO-STBC, RAR-QOSTBC, Taha