A Low Complexity Decoder for Quasi-Orthogonal Space Time Block Codes

In this paper, a low-complexity suboptimal decoder for coherent and non-coherent quasi-orthogonal space time block codes with three and four transmit antennas is proposed. Our decoder enjoys a nearly linear complexity and approximately the same performance as the optimal maximum-likelihood (ML) decoder. Simulations show the advantages of the proposed decoder with respect to several other popular approaches to the coherent and non-coherent decoding.