ECA: Exclusive Cell Allocation for Autonomous Scheduling in Time-Slotted Channel Hopping

Time-slotted channel hopping (TSCH) is a synchronous MAC protocol designed to meet the requirements of many Internet of Things systems and applications. TSCH requires a scheduling scheme to construct a rendezvous schedule between a communication pair, and autonomous scheduling is the state-of-the-art approach where each node schedules autonomously without extra control overhead. However, autonomous scheduling is oblivious of the schedules of other nodes due to its autonomous and thus near-sighted characteristic, and this gives rise to the cell conflict problem where multiple nodes attempt to communicate with a single node simultaneously, leading to communication failures and network performance degradation. To this end, we proposed ECA, an exclusive cell allocation scheme for autonomous scheduling in TSCH. ECA utilizes the parent–child relations in routing information to construct a local regulation that ensures exclusive cell allocation without additional control messages. Moreover, ECA is compatible with existing autonomous scheduling schemes such as ALICE and A3. We implement ECA on real embedded devices using ContikiOS, and evaluate on a 71-node testbed to confirm that ECA improves link-layer packet reception ratio by 39.8%, latency by 86.3%, and end-to-end packet delivery ratio by 22.9%.