Institute of Electrical & Electronic Engineers
The source and relay pre-coders are jointly optimized for an amplify-and-forward multiple-input multiple-output relay system. Both the source and relay nodes employ Orthogonal Space-Time Block Codes (OSTBC), and have imperfect channel state information of the source-relay and relay-destination channels, respectively. Using the worst-case robust design approach, the authors show that the problem of maximizing the minimum signal-to-noise ratio at the destination can be exactly reformulated as a convex optimization problem. Further, they provide an approximate semi-analytical approach which significantly reduces the computational cost of solving the convex problem.