Degree Distribution Based MIMO - LDPC Scheme

In this paper, an LDPC based MIMO scheme is proposed in which matrix modulation scheme of MIMO and unequal protection ability of irregular LDPC codes are employed. The new scheme named degree distribution based-MIMO (DDB-MIMO for short) combines the two schemes, in which the important bits with large degrees are transmitted in transmission diversity (TD) symbols and bits with small degrees are mapped to the spatial multiplexing (SM) mode symbols. Since the TD mode could offer more protection to the data streams by offering more transmission power, the important bits with large degrees which could contribute more to the decoding process would have more protection from TD mode and hence the system performance would be improved namely. The performance of the new scheme has also been evaluated by the Gaussian approximation (GA) scheme which is used to analyze the asymptotic performance of LDPC coded system. The analysis results provide us the optimal mapping fractions between the bits with different degrees and transmitted symbols in different modes which is almost the same as the DDB-MIMO scheme offering. The simulation results also proved the new scheme.