Designs of MIMO Amplify-and-Forward Wireless Relaying Networks: Practical Challenges and Solutions Based on MSE Decomposition

Amplify-and-forward (AF) relaying is an efficient way to extend radio range and improve link reliability with a low implementation cost. While the research on the AF relaying in a single-antenna scenario has matured, its application to broadband radio transmission utilizing multiple-input multiple-output techniques still needs more effort to overcome several practical challenges, such as large overheads for channel estimation and vulnerability to the channel estimation errors. This paper reviews some recently proposed linear transceiver designs based on the minimum mean squared error (MSE) criterion and shows that the proposed MSE decomposition and relaxation method can lead to an efficient solution for those challenges. Insightful observations and comprehensive discussions are also made on both analytical and numerical results from practical implementation perspectives.