Parallel soft ZF detection for turbo-coded QO-STBC scheme

A zero forcing (ZF) decoder using the pseudo inverse of a channel matrix is generally used for detection of quasi-orthogonal space time block coding (QO-STBC). This ZF detection for QO-STBC should sacrifice not only the decoding complexity but also the diversity gain compared to a simple linear detection for orthogonal STBC schemes. This disadvantage of QO-STBC schemes are mainly result from the interference terms in the detection matrix. In this paper, we propose a parallel detection scheme for QO-STBC, which may enhance the computational efficiency compared to the conventional ZF scheme, especially when combining with turbo codes. We present a very efficient soft decision metrics to be used at the iterative decoder for turbo codes. The simulation results in this paper reveal that the proposed detection scheme produces an almost the same performance to that of the the maximum likelihood (ML) detection, with greatly enhanced computational efficiency.