Power Allocation in Two-Hop Amplify-and-Forward MIMO Relay Systems with QoS requirements

摘要

The problem of minimizing the total power consumption while satisfyingdifferent quality-of-service (QoS) requirements in a two-hop multiple-inputmultiple-output network with a single non-regenerative relay is considered. Asshown by Y. Rong in [1], the optimal processing matrices for both linear andnon-linear transceiver architectures lead to the diagonalization of thesource-relay-destination channel so that the power minimization problem reducesto properly allocating the available power over the established links.Unfortunately, finding the solution of this problem is numerically difficult asit is not in a convex form. To overcome this difficulty, existing solutionsrely on the computation of upper- and lower-bounds that are hard to obtain orrequire the relaxation of the QoS constraints. In this work, a novel approachis devised for both linear and non-linear transceiver architectures, whichallows to closely approximate the solutions of the non-convex power allocationproblems with those of convex ones easy to compute in closed-form by means ofmulti-step procedures of reduced complexity. Computer simulations are used toassess the performance of the proposed approach and to make comparisons withalternatives.