Joint beamforming and power control in a spatial cooperative multiplexing network with multiple source-destination pairs

To exploit multiuser spatial cooperative diversity, relay nodes can assist the transmission of signal from multiple sources to their corresponding destinations in order to combat the noise, the channel fading and the cross-interferences. In this work, we consider a network consisting of N source-destination pairs and a set of M relay nodes. We assume that a fixed total budget of transmit energy is available for allotment among all transmitters, i.e., the source and relay nodes. For such network, we consider the time division Amplify-and-Forward (AF) scheme in 2N time slots, and propose an algorithm to optimize the beamformers and the powers allocated to all transmit nodes. The proposed method maximizes the network sum capacity assuming that the channels state information (CSI) is known. Numerical simulations illustrate the significant improvement obtained under power constraint. This betterment is more pronounced for low power regimes.