Meet the PAREO Functions: Towards Reliable and Available Wireless Networks

Deterministic networking allows carrying data flows with low data-loss rates and with bounded latency. A typical use-case is the convergence of Operational Technology (OT) with Information Technology (IT), also known as the Industrial Internet. Wireless networks operate on a shared communication medium where the potential external interference along with multi-path fading impact data packet delivery. By employing diversity in the time, frequency and spatial domains, wireless technologies with scheduled transmissions, such as IEEE Std 802.15.4-2015 Time Slot Channel Hopping (TSCH), can mitigate those effects and provide Reliable and Available Wireless (RAW) communications that approach determinism. Nevertheless, a radio link operating in the ISM band still needs to handle collisions and possibly re-transmission. Therefore, It takes redundant links and paths to provide both the high availability and the near consistent reliability that industrial applications require. In this paper, we present the Packet Automatic Repeat reQuest (ARQ), Replication and Elimination (RE), and Overhearing (PAREO) functions to further increase the Quality of Service (QoS) in industrial networks, even when implemented on top of best-effort traffic in a shared network. The results show that PAREO provides up to approximately 6 times lower Packet Error Rate (PER) and up to approximately 10% higher energy consumption than the default RPL implementation with 7 retransmissions, while keeping jitter and latency as low as default RPL with 1 retransmission.