Distributed Multiuser Beamforming for Relay Networks in Frequency-selective Channels

In this paper, a distributed peer-to-peer beamforming technique in frequency-selective relay networks is proposed. It is assumed that all the relay nodes use Filter-and-Forward (FF) protocol to compensate for the source-to-relay and relay-to-destination channels. All the channels of the active source-destination pairs are considered to be frequency-selective. The beamforming strategy that minimizes the total relay transmitted power subject to the Quality-of-Service (QoS) constraints for all of the destination nodes is considered. The resultant problem is approximately solved using Semi-Definite Programming (SDP). Simulation results demonstrate that in frequency-selective multiuser relay networks, the proposed technique substantially outperforms the existing