Abstract
Equipped with base station hardware, unmanned aerial vehicles (UAVs) can act as drone small cells (DSCs) to complement the traditional terrestrial small cells (TSCs) in providing ubiquitous connectivity for a wide range of applications. Although the performance of drone-assisted heterogeneous networks has been investigated, the state-of-the-art adopts simplified channel models that are not applicable to practical network scenarios. To make an accurate analysis on the network performance, and provide guidelines for the practical design of cell association and network deployment strategy, in this work, we consider a drone-assisted heterogeneous network that employs a flexible biased cell association policy and adopts a more general channel model that incorporates line-of-sight (LoS) and non-line-of-sight (NLoS) components for both air-to-ground (ATG) and ground-to-ground (GTG) transmissions. We develop a unifying analytical framework to evaluate the network performance in terms of coverage probability, area spectral efficiency (ASE) and user throughput. Our results show that 1) deploying DSCs to complement traditional TSCs can only deteriorate the network performance within the ultra-dense network region, 2) by optimally setting the bias factor for cell association policy, the network performance can be further enhanced.