A PDF estimation-based iterative MIMO signal detection with unknown interference

Abstract—The equivalent diversity order of iterative minimum mean squared error (MMSE) multiuser detectors for multiple input multiple output (MIMO) channels is decreased if they aim at suppressing unknown cochannel interference (UCCI) while detecting multiple users ’ signals. In this letter, we propose a new MIMO signal detection scheme with the aim to preserve the detector’s diversity order by estimating the probability density function of the UCCI plus background noise. It is shown that the proposed detector significantly outperforms the conventional detector based on UCCI’s covariance matrix estimation. Index Terms—Channel estimation, cochannel interference, equalization, multiple input multiple output (MIMO), minimum mean squared error (MMSE), probability density function (PDF) estimation, turbo multiuser detection. I