Thorough Investigation of multipath Techniques in RPL based Wireless Networks

With the growth of the Internet of Things appliances in industrial environments, known as Industry 4.0, wireless multihop network solutions have been attracting more attention in the past years. The IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) is the de facto protocol for Low-power and Lossy Networks specially designed for industrial use-cases. However, the default operation of RPL does not provide a high level of network reliability and low jitter performance. The use of IEEE Std 802.15.4-2015 Time Slot Channel Hopping (TSCH) at the Medium Access Control layer can mitigate the effects of external interference by re-transmitting over different radio frequency. Still, this standard does not support possible link failures or node over-the-air programming. In this paper, we propose the use of multiple disjoint paths to enforce reliability and availability when both RPL and TSCH standards are used. Indeed, we propose and compare two approaches based on the principle of replication: i) packet replication at the source node only, and ii) packet replication at the source node and scattering if two replicas merge. We implemented these two algorithms in Contiki OS and evaluated their trade-offs over the simulated network environment provided by COOJA. Finally, we compare these solutions against the state-of-the-art Packet Automatic Repeat reQuest (ARQ), Replication and Elimination (RE), and Overhearing (PAREO) technique that proposes a braided multipath pattern.