RESCUE: Renewable Energy Small Cells for Utility Enhancement in Green LTE HetNets

In this paper, the green operation of heterogeneous LTE cellular networks is investigated. In addition to macrocells, small cells are used to offload traffic and increase the capacity of the network. A combination of mains-powered small cells and renewable energy small cells (RESCs) is considered, where the latter corresponds to small-cell base stations powered by renewable energy sources, e.g., solar panels or wind turbines. Thus, the presence of RESCs allows not only to offload macrocell traffic but also to optimize energy performance by switching off other mains-powered small cells whenever possible. Both the uplink and downlink directions are considered in the analysis, while taking into account dynamic resource allocation and the impact of intercell interference. A utility maximization approach is proposed, where weighted utility functions take into account both the quality-of-service (QoS) performance of the network and its energy consumption. The use of RESCs for utility enhancement (RESCUE) leads to interesting results, especially when the utility function presents a judicious balance between QoS and energy efficiency.

I. Introduction

The explosion in rich media content, such as audio, video, and gaming, is significantly increasing the load on cellular systems. State-of-the-art and next-generation cellular systems have to cope with the mobile data growth. The number of cells required to meet the capacity demands is expected to increase significantly. Solutions to meet the increasing demand include the deployment of heterogeneous networks (HetNets) involving macrocells and small cells (picocells, femtocells, etc.), distributed antenna systems (DAS), coordinated multipoint (CoMP) communication, relay stations (RS), and the use of D2D communications [1], [2]. In fact, HetNets are expected to constitute a paradigm shift in the state-of-the-art cellular networks [3], and they constitute an interesting solution for network densification, which is a main theme for the evolution of cellular networks into 5G [2].