H-SATMAC: A Hybrid Self-Adaptive TDMA-Based MAC Protocol for Large-Scale UAV Ad-Hoc Networks

Unmanned aerial vehicle (UAV) ad-hoc network is expected to play an important role in the integrated sensing and communication (ISAC) due to its flexible topology and low cost, enabling scalable connectivity. However, the line-of-sight and node mobility of UAVs lead to severe wireless interference and highly dynamic network topology, making the design of distributed medium access control protocols for large-scale UAV adhoc network a critical problem. Here, we propose H-SATMAC, a hybrid self-adaptive TDMA-based MAC protocol for largescale UAV ad-hoc networks. In order to jointly consider the transmission of the periodic and aperiodic packets, we design a hybrid channel resource scheduling method based on time slot groups. The consecutive free time slots in the group are used as the contention window for CSMA-based transmissions. We utilize a dynamic mapping of slot groups and the geohash coding system to avoid hidden terminal problem and loadbalance multiple group resources. Besides, an enhanced time slot adjustment and adaptive frame length method is designed to achieve better channel utilization while avoiding channel collisions between nodes. We conduct theoretical analysis and extensive simulations to evaluate H-SATMAC. Simulation results show that H-SATMAC achieves 22 and above 64 that of the reference protocol.