MMSE-Based Non-Regenerative Multicarrier MIMO Wireless Relay Communications with Direct Source-Destination Link

In this paper we propose non-regenerative multi- carrier multiple-input multiple-output (MIMO) relay techniques that minimize the mean-squared error (MSE) of the signal waveform estimation. In particular, we consider the practical scenario where the direct source-destination link can not be neglected and develop an alternating technique to minimize the signal MSE. In order to reduce the computational complexity of the alternating algorithm, a suboptimal non-alternating preceding approach is proposed. Numerical examples illustrate a significant performance improvement of the proposed algorithms compared with the existing techniques.