Sum-Rate Maximization with Minimum Power Consumption for MIMO DF Two-Way Relaying: Part I - Relay Optimization

摘要

The problem of power allocation is studied for a multiple-inputmultiple-output (MIMO) decode-and-forward (DF) two-way relaying systemconsisting of two source nodes and one relay. It is shown that achievingmaximum sum-rate in such a system does not necessarily demand the consumptionof all available power at the relay. Instead, the maximum sum-rate can beachieved through efficient power allocation with minimum power consumption.Deriving such power allocation, however, is nontrivial due to the fact that itgenerally leads to a nonconvex problem. In Part I of this two-part paper, asum-rate maximizing power allocation with minimum power consumption is foundfor MIMO DF two-way relaying, in which the relay optimizes its own powerallocation strategy given the power allocation strategies of the source nodes.An algorithm is proposed for efficiently finding the optimal power allocationof the relay based on the proposed idea of relative water-levels. Theconsidered scenario features low complexity due to the fact that the relayoptimizes its power allocation without coordinating the source nodes. As atrade-off for the low complexity, it is shown that there can be waste of powerat the source nodes because of no coordination between the relay and the sourcenodes. Simulation results demonstrate the performance of the proposed algorithmand the effect of asymmetry on the considered system.