LMSF: Lightweight Minimal Scheduling Function for 6TiSCH Networks

Link scheduling is a core component of 6TiSCH networks, specifying which link is allowed to transfer packets at what time and in which channel. For 6TiSCH networks, the IETF recently published Minimal Scheduling Function (MSF). The 6TiSCH network employs the IEEE 802.15.4 Time Slotted Channel Hopping (TSCH) as MAC layer protocol which instructs how to utilize a communication schedule for communication in the network. However, TSCH does not define how the schedule is built and managed. In this regard, MSF provides instructions on managing the communication schedule and adapts the schedule according to the traffic demand. However, MSF updates cell scheduling by unity even when traffic demand changes massively, and it follows a reactive strategy to act upon cell scheduling. As a result, 6P negotiation overhead is high, and it experiences longer delays. This paper proposes to use well-established Poisson distribution for traffic estimation. Then, based on its estimation, the 6P negotiation is adjusted so that a node can directly adapt to high variations in traffic demand. The proposed Lightweight Minimal Scheduling Function (LMSF) is evaluated with the 6TiSCH simulator. LMSF significantly reduces 6P negotiation overhead. Also, it consumes less energy and shows better latency and reliability performances than the standard MSF.