Abstract
Time Slotted Channel Hopping (TSCH) is an amendment of the IEEE 802.15.4 working group to provide a low-power Medium Access Control (MAC) for the Internet of Things (IoT). This standard relies on techniques such as channel hopping and bandwidth reservation to ensure both energy savings and reliable transmissions. Since many applications require low end-to-end delay (e.g. alarms), we propose here a distributed algorithm to schedule the transmissions with a short end-to-end delay. We divide the network in stratums, regrouping all the nodes with the same depth in the DODAG constructed by RPL. Then, different time-frequency blocks are assigned deterministically to each stratum. By appropriately organizing the blocks in the slotframe, we are able to deliver a packet before the end of the slotframe, whatever the route length is. We present a simple analytical study to define the initial size of each block in a homogeneous scenario. We experimentally analyze the behavior of our strategy to validate its ability to provide both high reliability and low latency in a distributed manner. (C) 2017 Elsevier B.V. All rights reserved.