Construction of quasi orthogonal STBC with minimum decoding complexity

In this paper, we formulate the algebraic structure of quasiorthogonal STBC with minimum decoding complexity (MDC-QOSTBC), whose maximum likelihood (ML) decoder only requires the joint detection of two real symbols, for any numbers of transmit antennas. We also propose a systematic method to construct an MDC-QOSTBC from an Orthogonal-STBC (O-STBC). The maximum code rate of the resultant MDC-QOSTBC is shown to be the same as that of the lower-order O-STBC used to construct it. We also find the optimum constellation rotation angle for the proposed MDC-QOSTBC construction to achieve full diversity and optimum coding gain. We can show that the proposed MDC-QOSTBC has more even power distribution over the transmit antennas, better scalability in adjusting the number of transmit antennas, and more superior decoding performance than the coordinate interleaved orthogonal design (CIOD) and asymmetric CIOD