Comprehensive Analysis of Heterogeneous Networks with Pico Cells in LTE-Advanced Systems

We have seen a rapid increase in mobile data traffic in cellular networks, especially in densely populated areas called “hotspots.” In order to deal with this trend, heterogeneous networks (HetNet) are attracting much attention as a method of effectively accommodating such traffic increases using the Long Term Evolution (LTE)-Advanced system in the 3rd Generation Partnership Project (3GPP). This paper first presents an overview of HetNet, where various wireless nodes can be deployed over the coverage area formed by macro base stations (BSs). Next, various evaluation results are provided for HetNet, where pico BSs (“Pico-BSs”) are deployed over the coverage area of macro BSs (“Macro-BSs”). Then, this paper presents a comprehensive analysis, not only of the effect of overlaying Pico-BSs but also a detailed analyses of the techniques called “cell range expansion (CRE)” and “enhanced inter-cell interference coordination (eICIC)” for facilitating the offloading of user terminals (UEs) from Macro-BSs to Pico-BSs and mitigating interference, respectively, for both downlink and uplink. Noteworthy outcomes found through the comprehensive study are that CRE provides throughput improvements for uplinks, especially for UE connected to Pico-BSs. In addition, this paper demonstrates that CRE contributes to improving downlink throughput especially for low traffic loads. The outcome regarding eICIC is that eICIC provides improvements in total throughput, in spite of the fact that eICIC causes unfairness between UE connected to the Pico-BSs and those with Macro-BSs. key words: heterogeneous networks, HetNet, pico base stations, CRE, eICIC