Minimal Idle-Listen Centralized Scheduling in TSCH Wireless Sensor Networks

Centralized scheduling in IEEE 802.15.4e Time Slotted Channel Hopping (TSCH), uses a centralized entity to perform scheduling of nodes in cells to generate collision-free communication amongst neighboring nodes. Although many centralized scheduling algorithms have been proposed, they still suffer from idle-listening, a state in which nodes stay awake without transmitting or receiving data, which causes wastage of the limited sensor node energy. This paper proposes a minimal-idle-listen centralized 6TiSCH scheduling algorithm (MILS) with the aim of minimizing idle listening amongst sender nodes. MILS is formulated as a Constraint Satisfaction Problem (CSP) problem, which schedules relay links in parallel with leaf links while maximizing the channels available in order to minimize waiting at bottleneck regions. Minimizing the number of packets in nodes close to the sink reduced delays by approximately 19% and idle-listening by 50% in MILS compared to OTF.