Bit-Interleaved Coded Transmission with Multilevel Modulation for MIMO-OFDM Systems

This paper proposes a bit-interleaved coded transmission with multilevel modulation for multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. In the proposed system, multiple layers are encoded and interleaved together, using one encoder and one interleaver, and then mapped by hierarchical symbol mapping. A corresponding receiver structure is presented, where multiple layers can be decoupled by iterative MIMO detection and equalization with ordered successive interference cancellation (SIC) and full log-likelihood ratio (LLR). Full LLR provides reliable estimates of transmit signals, and significantly improves the performance of proposed multilevel modulation. Simulation results show that the proposed system has better performance than conventional modulation schemes such as bit-interleaved coded modulation (BICM) and multilevel BICM (MLBICM).