Aerial-Terrestrial Heterogeneous Networks for Urban Air Mobility: A Performance Analysis

Urban air mobility (UAM) is increasingly capturing the attention of researchers and industry experts, as it holds the promise of providing faster and more economical solutions for urban commuting. Ensuring reliable communication for UAM aircraft is of paramount importance in maintaining operational safety. To that end, we use stochastic geometry tools to analyze the joint uplink-downlink coverage probability of an integrated aerial-terrestrial heterogeneous network (HetNet) for UAM aircraft, specifically electric vertical takeoff and landing (eVTOL) vehicles. We assume eVTOLs travel on predefined air corridors which are modeled as a Poisson line process (PLP). Furthermore, we model the spatial distribution of eVTOLs as a Matern hardcore process (MHCP) with a designated safety distance. We model the aerial base stations (ABSs) as a two-dimensional (2D) binomial point process (BPP), and the terrestrial base stations (TBSs) as a 2D Poisson point process (PPP). We use a suitable air-to-ground channel model to include line-of-sight (LOS) and non-line-of-sight (NLOS) transmissions. In the paper, we derive distance distributions to the closest ABS, LOS TBS, and NLOS TBS to a typical eVTOL, then we provide the association probability of each BS. Furthermore, we characterize the uplink interference and derive Laplace transforms for the PLP-MHCP distributed eVTOLs. Finally, we derive the coverage probability of the overall HetNet and carry out Monte Carlo simulations to validate our expressions.