Fast block-wise signal processing for layered STBC systems

In this paper, the block-wise lattice representation of the real-valued system model for the layered space time block code (layered STBC) system is introduced to reduce the computational complexity of the detection. Due to the orthogonality of the Alamouti STBC, the equivalent real-valued channel matrix of the signal model also has the orthogonal property. We take the orthogonal property into account thoroughly and propose two fast block-wise matrix computation schemes for the MIMO detection, including the block-wise Householder QRD and block-wise sorted QRD. We also show that the matrices obtained form the QRD of the equivalent channel matrix preserve the real-valued Alamouti coded patterns. The results of the proposed schemes are then utilized in the block-wise tree search detection, where the parallel procedure is performed to detect signals in the same block independently. Compared with the single-wise signal processing, the block-wise signal processing can save about 75% of the computational complexity at the preprocessing phase of the tree-search detectors.