Abstract
As user applications become more diverse and data rate-hungry, networks emerge into heterogeneous and flexible forms. Unmanned aerial vehicles (UAV) play a prominent role in achieving a next level of flexibility thanks to their rapid deployment, low cost and favorable propagation conditions. One of the most important aspects of UAV-assisted heterogeneous networks (HetNets) is the user association strategy. In this regard, we propose an instantaneous-sense association strategy, as opposed to the widely adopted average-sense one. We study the association performance in a two tiers mmWave HetNet, where a terrestrial network is supported by a tier of UAV BSs (UBS). In specific, using tools from stochastic geometry we provide tractable expressions for the association probability with each tier in addition to expression for coverage hole probability taking into account the users’ reception sensitivity. Monte Carlo simulations are provided to validate the accuracy of analytical formulas, and it is shown that the average-sense association strategy is a special case of the proposed method.