A QRD-Based Chase Decoding Algorithm for Quasi-Orthogonal Space-Time Block Code Systems

In the paper, we proposed a Chase decoding algorithm (Chase-QRD-SIC) based on QR decomposition. The analysis and simulation show that the fewer number of transmit antennas, the closer performance of the proposed algorithm is to maximum- likelihood (ML) algorithm. Its performance is virtually identical to ML decoding for 2 times 2 V-BLAST systems. At the same time, the 4 times 4 QOSTBC systems can be decomposed into two independent 2 times 2 QR-decomposition sub-systems according to the Equivalent Virtual Channel Matrix (EVCM) model. The proposed algorithm is applied to each of the sub-systems. The simulation shows that the new decoding scheme is able to achieve ML performance for 4 times 4 QOSTBC systems, and the complexity of the new scheme is lower than that of the conventional ML decoding due to the reduced number of paths used for calculating ML metrics.