Four-Group Decodable Semi-Orthogonal Algebraic Space-Time Block Codes

The rate-one semi-orthogonal algebraic space-time (SAST) codes is recently introduced. In this paper, the authors propose a new signal design method for SAST codes so that the transmitted symbols can be divided into four groups for maximum likelihood (ML) detection; the authors call this new design of SAST codes four-group decodable SAST (4Gp-SAST) codes. The decoding complexity of 4Gp-SAST codes is greatly reduced compared with that of the original SAST codes, where the ML decoding of the transmitted symbols is made into two groups. The exact pair-wise error probability of 4Gp-SAST codes is derived and it is used to optimize the signal designs. Simulation results show that 4Gp-SAST codes perform better than several low complexity space-time block codes such as orthogonal and quasi-orthogonal codes.