Coherent Relaying in Cooperative MIMO Communication Systems
Yi Zheng, Hani Mehrpouyan, Steven D. Blostein · 2009
In this paper we propose an enhancement to the Amplify and Forward (AF) protocol. The proposed multi-relay scheme assumes that the source, destination, and each relay have M, N, and 1 antennas, respectively. It is assumed that the source does not have access to the channel state information and takes advantage of uniform spatial multiplexing. Unlike the conventional AF scheme, the proposed scheme allows for each relay to adjust the phase of received signal before applying the AF protocol. Imperfect channel estimation and its effect on the performance of the multi-relay scheme is also investigated. In determining the parameters, conventional optimization schemes cannot be applied due to the non-convex nature of the function. A low complexity method is used to optimize the system that utilizes bisection search. Numerical calculations of capacity and BER simulations demonstrate a significant performance gain over conventional AF. I.