Abstract
This paper focuses on a robust distributed power allocation scheme for downlink two-tier heterogeneous networks (HetNets). The objective is to maximize the network aggregate utility of femtocell users (FUEs) which factors the fairness between users under the constraint of not causing serious interference to existing macrocell users (MUEs). Being impractical for different nodes to cooperate in HetNets to obtain precise estimated values of the channel gains between them, it is a challenge to guarantee the performance of the power allocation algorithm by using existing methods. This work makes a step forward in the direction of conquering this challenge by taking into account channel uncertainty, and the robust counterpart of nominal problem, without channel uncertainty, is framed by using worst-case robust optimization theory. To make the robust counterpart computationally tractable, we exploit its convexity and derive that the channel uncertainties between a FUE and nearby femtocell base stations (FBSs) fall into water-filling form being related to the received power from interference sources. Based on the inherent relationship between channel uncertainty and received power, we design a distributed algorithm which merely needs to solve a deterministic problem. The algorithm is devised based on alternating direction method of multipliers (ADMM) with a fast convergence speed. The simulation results demonstrate the robustness of our proposed approach, and the corresponding cost of robustness is investigated.
Highlights
Femtocell base stations (FBSs) are low-power nodes to provide high throughput and customized services to users, and together with macrocells, they form heterogeneous networks (HetNets)
To the best of the authors’ knowledge, [18] is the first paper to apply worst-case robust optimization to power control in HetNets. They discuss the effect of channel uncertainty on the Quality of Service (QoS) of macrocell users (MUEs) and the energy efficiency of femtocell users (FUEs), whereas we investigate the fairness between FUEs
The outage probability is defined as the ratio of the number of MUEs who suffer the interference from FBSs above a predefined threshold (Imt ) to the total number of MUEs
Summary
Femtocell base stations (FBSs) are low-power nodes to provide high throughput and customized services to users, and together with macrocells, they form heterogeneous networks (HetNets). Deploying femtocells is an effective and efficient way to increase wireless network capacity, and it provides great benefits to network operators by producing new services. Along with their small size, low cost, and plug-and-play features [1,2], femtocells are considered as a big thing [3] in both existing and future mobile communications. We emphasize the power allocation of FBSs. The objective is network utility maximization (NUM) with respect to femtocell users (FUEs) under the constraint of not interfering MUEs, which is similar to the underlay scenario in cognitive radio networks
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