Cooperative Beamforming Based Selection and Power Allocation for Relay Networks

In this paper, we consider cooperative beamforming in an amplify-and-forward (AF) cooperative network with multiple relay nodes.Specially, only "appropriate" relay nodes are selected to perform cooperative beamforming. Source node can determine the relay nodes with just mean channel gain, which will reduce the complexity of obtaining instantaneous channel state information (CSI). This scheme guarantees that the energy is allocated to those "appropriate" relay nodes, and accordingly improves the energy efficiency. Therefore, it is able to provide superior diversity over the conventional cooperative beamforming. We also prove that power allocation (PA) between source and selected relay nodes is a convex problem, which can be resolved with lower computational complexity. Simulation results demonstrate that our scheme achieves an essential improvement in terms of outage performance, as well as high energy-efficiency for energy-constrained networks.