End-to-End Delay Analysis in Aerial-Terrestrial Heterogeneous Networks

Recently, the use of unmanned aerial vehicles (UAVs) or airship platforms to improve the performance of cellular networks has received growing interests. It is expected that the next generation cellular networks will enable the low-latency and high-reliability communications with the support of aerial-terrestrial heterogeneous networks (HetNets) composed of flying and ground base stations (BS). In addition, with the emergence of various delay-sensitive applications (e.g., autonomous vehicles), the end-to-end delay becomes a crucial quality of service (QoS) metric. However, how to design an efficient and delay-guaranteed aerial-terrestrial HetNets remains an open research challenge. In this paper, we develop an analytical approach to characterize the end-to-end delay performance of aerial-terrestrial HetNets by using network calculus. A stochastic model that takes into account the successful transmission and resource utilization in the radio access network is proposed to evaluate the delay performance within a target delay-violation probability. In addition, the effect of background traffic in the core network are carefully examined to present a tight upper bound for the end-to-end delay. Simulation results validate the proposed analysis under different network settings such as available bandwidth, the number of UAVs, and the trajectory of UAVs. Also, it is revealed that the trajectory of UAVs plays a more significant role in the delay performance compared to the number of UAVs.