On Array-Processing-Based Quasi-Orthogonal Space–Time Block-Coded OFDM Systems

In this paper, we propose a quasi-orthogonal space-time block coding (QO-STBC) orthogonal frequency-division multiplex (OFDM) scheme for its application in frequency-selective channels. A novel decoding approach for QO-STBC OFDM is introduced, and it works based on an array-processing technique. The received QO-STBC OFDM symbol array is decomposed by null spaces of the split-up channel matrices, followed by a parallel decoding unit, as an effort to reduce the computational complexity and latency induced by the decoding process. The performance of the proposed system is evaluated over frequency-selective channels by both analysis and computer simulations to show the effectiveness of the scheme.