A fast decoding for space time block codes

We present an algorithm based on closest point search (CPS) in lattices for decoding of space-time block codes (STBC). The modified CPS algorithm based on Schnorr-Euchner variation of the Pohst (1981) method is used to perform the decoding of STBC. This method is shown to be substantially faster than other known sphere decoding methods. Also we exploit a fast method for decoding of orthogonal STBC with low complexity, that its complexity is polynomial in the number of antennas and the rate. We show that our method gives the same decoding performance as the maximum-likelihood (ML) ratio decoding while it shows much lower complexity.