Power allocation in two-hop amplify-and-forward MIMO relay systems with QoS requirements

The problem of minimizing the total power consumption while satisfying different quality-of-service requirements in a two-hop multiple-input multiple-output network with a single non-regenerative relay is considered. As shown by Y. Rong in [1], finding the solution to this problem is hard as it is not in a convex form. To overcome this difficulty, in this work a novel approach is proposed that allows to closely approximate the solution of the non-convex problem with that of a convex one easy to solve in closed-form by means of a multi-step procedure of reduced complexity. Computer simulations are used to assess the performance of the proposed solution and to make comparisons with existing alternatives.