Energy efficient power allocation and relay selection in MIMO relay channels

Wang, Zijian Vandendorpe, Luc [UCL]

In this paper, we consider the energy efficiency (EE) maximization problem for MIMO-relay channels with relay selection and individual power constraints for each node. We implement Dinkelbach's method for the whole system to iteratively select the relays. Closed-form expressions of the precoding matrix at the source and the beamforming matrix at the selected relay are obtained thanks to the concavity of the objective function. We also give the mathematical property of monotonicity which guarantees that the values of Lagrangian multipliers can always be found. Finally, we give the numerical results illustrating the performance gain due to relay selection.