Recently I’m reading paper[1][2] related to my interest. while here are some questions about Traffic Aware Scheduling Algorithm of Time Slotted Channel Hopping mode in 802.15.4e which I could’t well understand.

It’s stated that “minimize the number of active time slots; such number direct impacts the end-to-end delay, and also the network duty cycle, and, thus, the network lifetime.” [2] introduction part, page 2.  I can get the point the duty cycle is reduced obviously, but on the average view, the end-to-end delay may not reduced as expected(e.g. if we always allow the deeper nodes that far from root transfer first, the average end-to-end delay maybe shorter). Also, once the traffic load(bit*meter) is determined, without other assumption like aggregators traffic reduction or additional routing method, we know nodes not transmitting or receiving are in inactive/sleep mode at each time slot, how can energy be saved compare to other method(e.g a method treat degree or level as priority when scheduling)? Or does it necessary mean less power consumption when we get least active slots? Are there any nodes that have to keep active for other consideration even they don’t have transmission load right now?

[1].Traffic Aware Scheduling Algorithm for reliable low-power multi-hop IEEE 802.15.4e networks

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6362805&newsearch=true&queryText=traffic%20aware%20scheduling%20algorithm

[2].On Optimal Scheduling in Duty-Cycled Industrial IoT Applications Using IEEE802.15.4e TSCH

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6525406