Adaptive Power Control for Asymmetric Two-Way Amplify-and-Forward Relaying With Individual Power Constraints

This paper addresses the problem of adaptive power control of a two-way amplify-and-forward (AF) relaying network based on outage probability minimization. Unlike most of the existing works, our network scenario has asymmetric traffic requirements, and each terminal in the network is subject to an individual power constraint in addition to a total power consumption constraint of the network. To fulfill power control, instantaneous or statistical channel state information (CSI) is assumed to be available at the transmitter of each terminal. By dividing the overall power control problem into a few subproblems corresponding to different power constraints, and using the traffic knowledge along with the CSI, two power control strategies, called short- and long-term strategies, are proposed, leading to closed-form solutions for individual transmit powers at the relay and the sources that are adapted to certain traffic requirements and channel conditions. Simulation results are provided to demonstrate the effectiveness of the proposed power control strategies. It is shown that the short-term strategy can achieve a significant performance gain in terms of the outage probability, regardless of symmetric or asymmetric traffics and channels, and meanwhile, the long-term strategy is more appropriate to asymmetric traffic and channel conditions.