  Time Slotted Channel Hopping (TSCH) is a Medium Access Control (MAC) protocol
introduced in IEEE802.15.4e standard, addressing low power requirements of the
Internet of Things (IoT) and Low Power Lossy Networks (LLNs). The 6TiSCH
Operation sublayer (6top) of IEEE802.15.4e defines the schedule that includes
sleep, transmit and receive routines of the nodes. However, the design of
schedule is not specified by the standard. In this paper, we propose a
contention based proportional fairness (CBPF) transmission scheme for TSCH
networks to maximize the system throughput addressing fair allocation of
resources to the nodes. We propose a convex programming based method to achieve
the fairness and throughput objectives. We model TSCH MAC as a multichannel
slotted aloha and analyse it for a schedule given by the 6top layer.
Performance metrics like throughput, delay and energy spent per successful
transmission are derived and validated through simulations. The proposed CBPF
transmission scheme has been implemented in the IoT-LAB public testbed to
evaluate its performance and to compare with the existing scheduling
algorithms.
