Novel Routing Approach for the TSCH Mode of IEEE 802.15.14e in Wireless Sensor Networks with Mobile Nodes

Wireless Sensor Networks (WSNs) are planned to support a wide range of industrial applications in the near future. The Timeslotted Channel Hopping (TSCH) mode of the IEEE 802.15.4e protocol has been specially designed for harsh industrial environments. In this context, the IETF 6TiSCH working group is currently defining how this standard must be adapted to Low-power and Lossy Networks (LLNs), such as WSNs. The uncertainty and dynamics of industrial environments, combined with the mobility of certain nodes complicates routing. In this paper, we present an extension of the 6TiSCH routing approach to handle the mobility of certain nodes in industrial scenarios. Routing among static nodes is managed using the same approach as 6TiSCH (RPL - IPv6 Routing Protocol for Low- Power and Lossy Networks). Then, we apply a novel position based approach to enhance the communications among mobile and static nodes. This combines end-to-end reliability estimations with a blacklisting process based on the node location. As a result, we can take advantage of the high reliability achieved by gradient-based routing techniques, and also handle the node mobility of non-static nodes. The simulation results indicate that the reliability of the communications among mobile and static nodes is increased, even with high positioning errors, compared to existent geographical routing approaches. As a result, the reliability and the robustness of the IEEE 802.15.4e WSNs with mobile nodes is enhanced even in harsh conditions.