Linear Non-Regenerative Multicarrier MIMO Relay Communications Based on MMSE Criterion

Abstract—In this letter we propose linear non-regenerative multicarrier multiple-input multiple-output (MIMO) relay tech-nique that aims to minimize the mean-squared error (MSE) of the signal waveform estimation at the destination. We generalize the existing result on the structure of the optimal relay amplifying matrix by considering the direct source-destination link. To minimize the MSE, a power loading algorithm is developed which has a significantly reduced computational complexity compared with existing techniques. Index Terms—MIMO, non-regenerative relay, multicarrier, MMSE, power loading. I