Efficient Air-ground Collaborative Routing Strategy for UAV-assisted MANETs

In UAV-assisted mobile ad hoc networks (UAMANETs), UAVs' extended communication range enables remote node connections with fewer hops. However, this extension exacerbates competitive MAC resource contention under high network loads, thereby limiting the throughput. To address this challenge, we first analyze the key factors to this limitation. Our analysis reveals that the extended range of UAVs increases the number of hidden terminals by several to tens of times compared to ground nodes, resulting in an exponential increase in packet collision probability and access delay. As network load increases, the increased packet collision probability and relay delay at UAVs result in unnecessary routing hops and delays, ultimately limiting throughput. On this basis, we propose the UAV-assisted Zone Routing Protocol (UZRP), where UAVs act as both network load controllers and packet relays. All network packets are utilized by UAVs as probes for topology tomography to prune unnecessary routing hops and provide routing for nodes through computation to reduce routing convergence delay. Furthermore, UAV-generated routing packets will prevent nodes from relaying routing packets, and theoretical analysis has proven its effectiveness in reducing routing overhead. Simulation results show that UZRP achieves nearly 70% overhead reduction and 30% throughput enhancement compared to ZRP.