Soft ZF MIMO detection for turbo codes

In this paper, we present a soft zero forcing (ZF) scheme for turbo-coded multi-input multi-output (MIMO) schemes. The complexity of maximum likelihood (ML) soft detection for turbo coded MIMO schemes increases exponentially by the number of antennas and modulation orders, and thus it is a NP hard problem. In this paper, we divide the soft detection process as three sequential steps and this highly reduces the computational complexity. The three sequential steps include ZF detection of the transmitted modulation symbol, soft demapping, and application of proper channel gain. We demonstrate the simulation results on fast and slow fading channels and show that the proposed soft ZF scheme can achieve just a dB power loss with dramatically reduced detection complexity compared to ML detection.