An adaptive bendable virtual tunnel routing protocol for flying ad-hoc networks

Flying ad-hoc networks (FANETs) play a crucial role in disaster response, surveillance, and remote sensing. However, their highly dynamic topology and frequent link disruptions pose significant challenges to efficient routing. Existing protocols suffer from excessive control overhead, unstable links, and inefficient energy utilization, that limits their practical deployment. To address these issues, we propose an adaptive bendable virtual tunnel routing protocol (ABVTR), which constructs a three-dimensional (3D) adaptive bendable virtual relay tunnel (3D-ABVRT) using Bézier curves. This tunnel restricts the propagation of route request messages, reducing redundant transmissions, and enhancing routing stability, particularly in sparsely connected UAV networks. ABVTR employs a piecewise function to align UAV movement with the tunnel's centerline, effectively minimizing deviations and reducing delays. Furthermore, it dynamically determines the next-hop node by considering movement direction, relative speed, and residual energy. The latter two factors are assessed using a S-function and an exponential function, respectively, to enhance link reliability and optimize energy distribution. This work advances the state-of-the-art by introducing a more adaptive, energy-efficient, and scalable routing solution for FANETs. The simulation results show that ABVTR significantly outperforms existing protocols (EARVRT, iPipe, HMGOC, CF-GPSR, FM-DT-GDR) in end-to-end delay, packet delivery ratio (PDR), and routing overhead. These enhancements position ABVTR as a highly promising solution for mission-critical FANETs application, enabling more resilient, scalable, and efficient aerial networks.