An energy efficient centralized scheduling scheme in TSCH networks

IEEE 802.15.4-2015 is the third revision of IEEE 802.15.4 Standard for Low-Rate Wireless Networks. The standard presents Time Slotted Channel Hopping (TSCH) Medium Access Control (MAC) protocol, which provides high reliability and low power consumption to various industrial applications. Despite the effectiveness and the importance of the TSCH protocol, the standard leaves out of its scope in defining how the schedule is built and maintained. In this work, we focus on scheduling in IEEE 802.15.4-2015 TSCH networks from the energy efficiency perspective in a centralized manner where the gateway makes frequency allocations and time slot assignments. At first, we derive an energy consumption model of a TSCH node to determine the network lifetime. Afterwards, we formulate the scheduling problem as an energy efficiency maximization problem, which is a nonlinear integer programming. Motivated by the high computational complexity of the problem, we propose a low-complexity Energy Efficient Scheduler (EES) and Vogel's Approximation Method Heuristic Scheduling Algorithm (VAM-HSA). We make a comparison with the Round Robin Scheduler (RRS) and analyse the schedulers in terms of success probability and energy efficiency. Performance evaluation indicates that EES and VAM-HSA perform better in terms of energy efficiency, while at the same time yielding a good throughput.