nT transmit and nR=nT receive antennas are deployed, the first code offers a transmission rate of (nT-1) with a minimum nulling diversity order of 3, whereas the second one offers a transmission rate of (nT-2) with a minimum nulling diversity order of 5. Therefore, the proposed codes significantly outperform the V-BLAST as nR=nT. Simulation results and discussions on the performance of the proposed codes are provided." />


On the Construction of High-Rate Quasi-Orthogonal STBC for MIMO QR Demodulation

Minh-Tuan LE  Van-Su PHAM  Linh MAI  Giwan YOON  

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E88-D   No.7   pp.1417-1429
Publication Date: 2005/07/01
Online ISSN: 
DOI: 10.1093/ietisy/e88-d.7.1417
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Section on Recent Advances in Circuits and Systems--Part 1)
Category: Communications and Wireless Systems
Keyword: 
space-time coding,  multiple-input multiple-output,  maximum likelihood detection,  diversity,  wireless communication,  multipath channels,  

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Summary: 
Orthogonal space-time block codes (STBCs) appear to be a very fascinating means of enhancing reception quality in quasi-static MIMO channels due to their full diversity, and especially their simple maximum-likelihood (ML) decoders. However, full-rate full-diversity orthogonal STBCs do not exist for more than two transmit antennas. Vertical layered space-time architecture (so-called the V-BLAST) with a nulling- and cancelling-based detection algorithm, in contrast, has an ability of achieving high transmission rates at the cost of having very low diversity gain, an undesirable consequence caused by the interference nulling and cancelling processes. The uncoded V-BLAST system is able to reach its ML performance with the aid of the sphere decoder algorithm at the expense of higher detection complexity. Undoubtedly, the tradeoff between transmission rates, diversity, and complexity is inherent in designing space-time codes. This paper investigates a method to increase the "nulling diversity gains" for a general high-rate space-time code and introduces a new design strategy for high-rate space-time codes detected based on interference nulling and cancelling processes, thanks to which high-rate quasi-orthogonal space-time codes for MIMO applications are proposed. We show that when nT transmit and nR=nT receive antennas are deployed, the first code offers a transmission rate of (nT-1) with a minimum nulling diversity order of 3, whereas the second one offers a transmission rate of (nT-2) with a minimum nulling diversity order of 5. Therefore, the proposed codes significantly outperform the V-BLAST as nR=nT. Simulation results and discussions on the performance of the proposed codes are provided.