An Interference Suppression Scheme for MIMO-OSTBC System

Multiple Input Multiple Output (MIMO) technique is considered as a cost-effective and promising technique for the next generation wireless system. Orthogonal Space-Time Block Codes (OSTBC) scheme is one of the most important coding schemes for MIMO system. The performance of an MIMO system using OSTBC (MIMO-OSTBC), however, degrades significantly in presence of strong interferences. In this paper, an interference suppression scheme for MIMO-OSTBC system in strong interference scenario is presented. The proposed scheme is based on simplified Maximum Likelihood (ML) decoding and noise subspace projection. The scheme has the following advantages: realizing ML decoding of the OSTBC and greatly reducing searching calculations by simple linear processing; avoiding matrix-inversion computation needed in ordinary suppression schemes through noise subspace projection. The paper also discusses the method of obtaining the efficient channel state information (CSI) needed in the proposed scheme in strong interference scenario. Simulation results are given to verify the interference suppression ability of the proposed scheme and our theoretical analysis. Compared with other suppression scheme, the proposed scheme has better SER performance and is more flexible in practical applications. Key-Words: MIMO, OSTBC, ML Decoding, Interference Suppression, Noise Subspace Projection,