High-reliability scheduling in deterministic wireless multi-hop networks

The industrial Internet of Things (IoT) relies on multi-hop radio paths. Synchronized nodes follow a Frequency-Time Division Multiple Access (FTDMA) schedule, but even using channel-hopping to mitigate interference, the radio links suffer packet losses. Resource allocation algorithms must consider the requirements of the applications in terms of delivery and allocate extra resource to compensate for anticipated losses. We propose a hop-by-hop allocation mechanism that extends the Traffic-Aware Scheduling Algorithm (TASA) by enabling retransmissions. We give each flow on the network the possibility to satisfy its applicative end-to-end delivery constraint. We keep the amount of resource allocated for retransmissions low, and balance the allocations on the relay nodes. By means of simulations, we show the gain in terms of reliability, and the cost in terms of number of allocations.