Optimal Detector for Single-User-Coded Signals in the Presence of Interference

The detection problem in the Gaussian interference channel is addressed, when each user employs an encoding scheme that is designed for the single-user Gaussian channel. A structure consisting of a separate symbol-by-symbol detector and a hard decoder is considered that is suboptimal compared to the maximum likelihood (ML) receiver, but also less complex. Given this structure, an optimal detector is presented that is compared to an interference-unaware conventional detector and an interference-aware successive interference cancellation (SIC) detector. It is demonstrated analytically and by simulation that the optimal detector outperforms both the conventional and the SIC detector, and that it attains decreasing symbol error rates even in the presence of strong interference.