Efficient frequency domain soft interference cancellation in Turbo MMSE equalization with MIMO system

An efficient frequency domain soft interference cancellation (FD-SIC) scheme is proposed for turbo frequency domain equalization (FDE) in multiple-input multiple-output (MIMO) system. At the transmitter, vertical-bell laboratory layered space-time (VBLAST) is suitable for multiple modulation and coding scheme (MCS) on different antennas, which can also enhance channel capacity. At the receiver, inter-antenna interference (IAI) is cancelled by prior information of data on other antennas from Soft-In Soft-Out (SISO) decoder at each iteration, which can improve the input signal to interference and noise ratio (SINR) of equalizer. Also conventional frequency domain Turbo equalization in MIMO system is derived. Then block (data of one transmit antenna) wise frequency domain minimum mean square error (MMSE) equalization is implemented, which utilizes prior information of all blocks. Symbol Log-likelihood ratio (LLR) is calculated from the output of equalizer. Simulation results show that the proposed scheme has better link performance than traditional algorithms.