Required number of small-cells in heterogenous networks with non-uniform traffic distribution

The operation of a primary macrocell (MC) network can be efficiently supported by secondary small cells (SCs) deployed in traffic hotspots and/or outage areas of the MCs. In this paper we consider a downlink heterogeneous network with frequency reuse-1 hexagonal MCs and non-uniform traffic density distribution. Assuming isolated SCs, we provide an analytical formulation for the average number of SCs (per MC) required to cover the hotspots areas and overcome outages within a MC (due to path loss and shadowing). The analytical framework is validated via simulations, confirming the agreement between the analytical results and the simulations. The expressions developed are useful as a tool to guide network design and subsequent deployment.