A fast sphere decoding algorithm fully exploiting the orthogonality of STBC

In this paper, we propose a fast sphere decoding (SD) algorithms for the STBCs whose symbols can be decoupled into several orthogonal groups. The orthogonality of the front levels and the last levels are both utilized, while all the former improved SD algorithms only consider the orthogonality of the last levels. By the proposed algorithm, weights calculation of the front and the last levels are respectively performed independently, thus the computational complexity is significantly reduced. As for the bit error ratio performance, it is not influenced at all. The simulation results show the advantage of our proposed fast SD in complexity economization over a former improved SD algorithm.