Pilot Matrix Design for Interim Channel Estimation in Two-Hop MIMO AF Relay Systems

In this paper, the authors are concerned with a two-hop Multi-Input-Multi-Output (MIMO) Amplify-and-Forward (AF) relay system consisting of a Source Node (SN), a Relay Node (RN), and a Destination Node (DN). Since the simple RN in this system is unaware of the structure of its received signal and incapable of performing complicated signal processing, the interim channels over the SN-RN and the RN-DN hops can not be estimated directly. Therefore, the authors develop a novel interim channel estimation approach in this paper.