Service Priority-Based Dynamic TDMA Protocol for FANETs

Abstract

With the increasing number of tasks undertaken by unmanned aerial vehicle (UAV) clusters, the corresponding flight ad hoc networks must process an increasing amount of service data, and different service types have different transmission requirements. According to these requirements, existing methods often prioritize high-priority packets at the expense of low-priority packets. To overcome this limitation, this paper proposes a dynamic time-division multiple access (TDMA) protocol based on service priority called the SPD-TDMA protocol. To meet the requirements of packet transmission with different priorities, a queue-scheduling algorithm based on maximum waiting time was designed. In this algorithm, packets received from upper-layer applications are allocated to different queues according to their priority, and a corresponding waiting time step is allocated to each queue. Packets with higher priority have shorter waiting times. When the transmission time slot arrives, the packets with the shortest remaining waiting time are sent preferentially, which not only meets the transmission requirements of high-priority packets but also effectively avoids the starvation of low-priority packets. On this basis, to optimize the usage of time-slot resources further, the SPD-TDMA protocol adopts a priority predictive time-slot scheduling mechanism to avoid overbooking time slots or wasting idle time-slot resources to improve the overall efficiency and throughput of the network. Simulation results based on OMNeT++ indicated that compared with the IEEE 802.11DCF, TDMA, and P-TDMA protocols, the proposed method increases the packet delivery rate by 80%, 58%, and 27%, and throughput by 85%, 58%, and 29%, respectively.