  Low-resolution precoding techniques have gained considerable attention in the
wireless communications area recently. Vital but hardly discussed in
literature, discrete precoding in conjunction with channel coding is the
subject of this study. Unlike prior studies, we propose three different soft
detection methods and an iterative detection and decoding scheme that allow the
utilization of channel coding in conjunction with low-resolution precoding.
Besides an exact approach for computing the extrinsic information, we propose
two approximations with reduced computational complexity. Numerical results
based on PSK modulation and an LDPC block code indicate a superior performance
as compared to the system design based on the common AWGN channel model in
terms of bit-error-rate.
