Layered autonomous TSCH scheduler for minimal band occupancy with bounded latency

Abstract

Robustness and bounded latency are among the key requirements in wireless industrial networks. A typical traffic patterns is convergecast, where sensors sends data towards a sink, resulting in a funneling effect with increased traffic intensity. This letter proposes the Layered autonomous Time Slotted Channel Hopping (TSCH) scheduler for convergecast traffic, which addresses the funneling effect while reducing the band occupancy. It divides the slotframe into layers where all nodes have one timeslot reserved for forwarding its own traffic. Layers are organized to allow spatially reuse such that traffic belonging to a node may be forwarded at multiple hops simultaneously. This is achieved autonomously by exploiting a node's knowledge of the routing topology. We evaluate the Layered scheduler through theoretical analysis and simulations in Cooja. Results show that Layered attains bounded latency even when nodes are utilizing all their available resources. This is achieved with significantly reduced band occupancy compared to Escalator, an autonomous scheduler for convergecast traffic. The performance is traded‐off by increased maximum latency.