Coverage and Rate of Low Density ABS Assisted Vertical Heterogeneous Network

A vertical heterogeneous network (VHetNet) is an integration of aerial base stations (ABS) into the terrestrial cellular networks. ABSs are anticipated to enhance the communications performance of the network because they are mobile and are quick to deploy suitable for on demand coverage. They promise a low-cost solution for ubiquitous connectivity especially in developing countries where telecommunications infrastructure and the power grid are limited. Accurate and tractable frame-works are required to adequately quantify the communications performance of a VHetNet. In this paper we develop an analytical framework for determining the coverage probability and average rate of a heterogeneous network with aerial, macro and small base stations. We considered a scenario with low density of ABSs suited to financially constrained countries and those with security concerns over flying machines. The results show that there is an optimum ABS altitude and density that maximize the coverage probability at a specific signal-to-interference ratio (SIR) threshold. The average rate increases with density at low SIR threshold of -10 dB while at 0 dB the optimum density decreases with altitude.