Simplified Maximum Likelihood detection for Hi Orthogonal Space-Time Block Coded system

A simplified maximum likelihood (ML) detector for H_i orthogonal space-time block coding (STBC) based on multi-step constellation reduction technique is presented. In the proposed algorithm, complexity is reduced by maintaining small ML search space, instead of searching over the entire constellation. The simulation results suggest that the proposed reduced search-space detection algorithm offers ML performance, while reducing the receiver complexity by more than 50% for the case of M-ary QAM and exactly 50% in case of M-ary PSK with M=16 as compared to the conventional ML detection. The complexity reduction is even more significant for higher modulation levels (M>16). The proposed technique is equally applicable to other STBC schemes.