Deterministic Networking (DetNet): Performance evaluation of the Packet Ordering Functions

Abstract

Industrial Internet of Things applications need strict Quality of Service guarantees, including when they use wireless networks. While existing standardization efforts, such as Deterministic Networks (IETF) and Time-Sensitive Networking (TSN), have focused mainly on wired networks, more recent activities address wireless networks, like the Reliable and Available Wireless (RAW) Working Group of the IETF. Duplicating packets over multiple paths can improve availability and reliability, but this can potentially result in more out-of-order packets. Existing reordering algorithms, including two recently standardized by the IETF, are not always well suited to wireless networks. As a result, guaranteeing a bounded end-to-end latency and/or maximum consecutive packet losses is still particularly challenging. We propose a novel packet reordering algorithm for deterministic networking that includes wireless segments to achieve lower end-to-end latency while providing high end-to-end reliability. We simulate a 6TiSCH wireless network to compare its performance with the existing ones. Furthermore, we also extend existing Network Calculus bounds on the reordering timer to obtain path-dependent values that can reduce the average latency. We also introduce a probabilistic model to compute the reordering ratio when there are no retransmissions that fits the simulation results.