Robust Power Allocation in Two-tier Spectrum-Sharing Femtocell Networks

This paper investigates the robust power allocation problem in spectrum-sharing femtocell networks, where there is one central macrocell and multiple femtocells. The problem aims to maximize the sum-rate of femtocell user equipments (FUEs) while guaranteeing the quality of service (QoS) of the macrocell user equipment (MUE) in the sparsely deployed scenario and densely deployed scenario of two-tier femtocell networks. Based on ellipsoid sets to describe channel uncertainties, we transform the formulated problem into a deterministic convex optimization problem adopting the worst-case optimization. We give the closed-form optimal robust power allocation of each FUE in the sparsely deployed scenario. In the densely deployed scenario, we obtain the lower bound on the sum-rate of FUEs. Simulation results demonstrate the effectiveness of the proposed robust power allocation algorithm.