Energy-efficient power allocation over multibeam satellite downlinks with imperfect CSI

In this paper, we address the power allocation problem over multibeam satellite downlinks. Different from conventional methods taking system throughput or rate matching as the optimization object, here this problem is modeled as energy efficiency (EE) optimization under the consideration of limited power resource in satellite. Furthermore, the imperfect channel state information (CSI) is taken into the model, which adds complexity to the problem. This optimization is a non-linear fractional problem and not convex, but it can be transformed into parametric programming. We deduce that the transformed problem owns convexity, and propose an efficient iterative algorithm to achieve the optimal solution with linear complexity. Simulation results show that this algorithm outperforms conventional schemes in terms of EE with guarantee of minimum demand rate. Particularly, the impacts of imperfect CSI and rain attenuation of the satellite channel are revealed by simulation.