Enabling Flow-level Reliability on FTDMA Schedules with efficient Hop-by-hop Over-provisioning

The industrial Internet of Things (IoT) relies on efficient and reliable communications from the source devices to the network gateways. The challenge resides in providing reliable multi-hop radio paths. Indeed, even in the case of synchronized nodes following a Frequency-Time Division Multiple Access (FTDMA) schedule, the radio links suffer from interference and packet losses. Resource allocation algorithms on FTDMA must take into account the requirements of the applications in terms of delivery. We propose two allocation mechanisms enabling retransmissions, first uniform, and second hop by hop. They give each flow on the network the possibility to satisfy its applicative end-to-end delivery constraint. By reducing the amount of resource necessary for retransmissions, and balancing the allocations on the relay nodes, we provide a robust and efficient resource allocation. In order to validate our approach, we implement our mechanisms enabling retransmissions on top of the state of the art algorithm, Traffic-Aware Scheduling Algorithm (TASA). By the means of simulations, we show the gains of our proposals in terms of reliability, and their cost in terms of number of allocations.