Toward Deterministic and Predictable Industrial 4.0 – TPI

To reduce the operational, automation, management and production cost and to simplify the production chain, the IoT technology is now considered in the industrial domain, also called the Industry 4.0, i.e., the 4th Industrial Revolution. The Industry 4.0 ambition is to make the factory more flexible and adaptable. The main goal is to replace the existing cables with a wireless medium, while guaranteeing network reliability above 99.999%. Furthermore, the Industry 4.0 requires robust communications, messages need to be sent securely and the communication framework must guarantee message delivery in a given delay with jitter close to 0. In addition, some environments may require a dense network, with thousand of nodes sending a large amount of messages. Scalability is thus another constraint imposed by the Industry 4.0. To reach this ambition, the wireless industrial networks must not only be reliable but also deterministic and predictable.

A deterministic network guarantees that the transported information will be carry out in a pre-defined and in a tight window of time, whatever the link quality and the network congestion. Moreover, a periodic process will be repeated identically every time. So the most important characteristic of the network is to exhibit a jitter (different on the consecutive packet inter-arrival time) close to 0. Determinism is a required property in the power grid, to ensure that high tension lines breakers can be activated within milliseconds, in public transportation to make sure that automated vehicles are operated safely for their passengers, and in industrial automation for control loops. However, the current technologies deployed for the IoT are based on best-effort packet switched network. Data are encapsulated within packets that are subject to variable delays in the network, due to retransmissions and enqueuing in intermediate nodes.

In 2016, the IEEE 802.15.4 standard was published to offer QoS for deterministic industrial-type applications. Time-Slotted Channel Hopping (TSCH) allows for competing the industrial standards. However, it does not avoid retransmissions when a data packet is lost, due to collision, or outage of one node. Moreover, the potential interferences, which lead to packet losses, with technologies operating on 2.4GHz, may decrease the reliability performance [4]. Since TSCH seems to be a good candidate solution, we propose to focus on implementing and extending the standard to bridge the gap between academia and Industry 4.0. Moreover, we propose to use distributed scheduling, multi-path routing and hybrid network to build the Industry 4.0 as presented in the following.

In this project, firstly, we plan to define algorithm and protocols for nodes to set up their network: select the “good” channel (i.e., less interfering channels) and discover their neighbor and the routes within the network. Then we will investigate in depth both the distributed and centralized scheduling solutions of 6TiSCH to identify the pros and cons, as well as their appropriateness for ultra-deterministic industrial networks. We will propose new dynamic scheduling, tightly coupled with routing algorithms over multiple interfaces. Moreover, we plan to propose isolated (dedicated) tracks to provide flow isolation, and to make the transmissions reliable and independent: each application has dedicated (i.e., reserved) bandwidth for its packets transmissions. Associating innovative and original forwarding techniques (such as duplication, overhearing, opportunism and glossy networking) and a dynamic and efficient scheduling will allow us to have a jitter close to 0, thus to fully control delays in the network. In addition to those new algorithms and protocols, we will provide a security threat analysis and provide countermeasure within our protocol to secure the network. Both simulation and experimental set up will be used to validate our work toward the Industrial IoT.