Modeling and Capacity Analysis of UAVs-assisted Three-tier Heterogeneous Wireless Networks

Abstract In this paper, we develop a system capacity analysis model for three-tier heterogeneous wireless networks in emergency scenarios. These networks comprise a device access layer, an Unmanned Aerial Vehicle (UAV) relay layer, and a backhaul layer. First, we derive the ergodic capacity of the device access layer using Non-Orthogonal Multiple Access (NOMA) communication, where the distribution of ground heterogeneous devices is modeled as a Poisson Point Process (PPP). Next, we formulate an optimization problem for the throughput rate of the UAV relay layer by analyzing resource allocation, with the maximum value representing the capacity of the UAV relay layer. To address the issue of unfair resource allocation, we introduce a satisfaction function as a new objective for the optimization problem. Then, we use a model based on independent and directional beamforming technology, which supports Space Division Multiple Access (SDMA) communication, to calculate the capacity of the backhaul layer. Finally, the overall system capacity is determined as the minimum capacity among the three layers. Analysis and simulation results demonstrate the accuracy of the proposed model. Additionally, compared to other schemes, the proposed resource allocation scheme for the UAV relay layer performs well in terms of user access fairness.