Areal capacity limit on the growth of small cell density in heterogeneous networks

We consider heterogeneous network (HetNet) systems comprising of two different types of base-stations (BSs): macro and small BSs. In the previous studies for HetNet, it is observed that the distribution of signal to interference plus noise ratio (SINR) is independent of the BS density. This implies that network throughput increases linearly with the number of BSs. In this paper, however, we have identified key practical factors which degrade the SINR distribution for dense HetNet. On the contrary to the previous studies, limited network throughput is verified by evaluating the areal capacity with respect to the density of BS under the practical channel model. The observation is made regardless of the deployment scenario whether the two types of BSs share the same frequency band or not. Based on the analysis and the simulation results provided in this paper, we present principal guidelines for cell deployment and system operation to improve the areal capacity of dense HetNet systems.

I. Introduction

The explosive growth of mobile data traffic leads to the evolution of conventional homogeneous cellular systems toward to heterogeneous network (HetNet) systems with densified cell deployment in order to improve the areal capacity. Compared to the conventional cellular systems which consist of homogeneous base-stations with macro cell coverage (macro BSs), the HetNet systems additionally include multiple BSs providing smaller cell coverage (small BS) within a macro cell area. However, it is difficult to estimate the areal capacity of HetNet systems due to its inherent complex interference environments.