Integrating A2 with TSCH: Bringing Network-Wide Agreement into a Recent Standard for the Internet of Things

Abstract

The vision of Internet of Things (IoT) as we know it has emerged immensely in the last couple of years, as the ever-growing demand for information continuously keeps increasing. A substantial contributing factor to the evolved vision of IoT is due to the convergence of multiple technologies including ubiquitous wireless communication and commodity sensors, paving the way for Wireless Sensor Networks (WSNs). The majority of WSNs constitute formations of small embedded, battery-driven sensor nodes (motes), wirelessly exchanging sensor information related to environmental conditions such as temperature, humidity, pollution levels and so on. In today’s society, WSNs are omnipresent in many different areas, stretching from the vehicle industry to areas concerning natural disaster prevention. In order to utilize the full potential of WSNs, motes need to reach network-wide agreement (consensus) in order for the whole network to agree on the outcome of a specific action. Consensus is a fundamental concept in distributed systems, but has received little attention in the low-powered wireless context due to the resource restricted constraints of such systems. Thus, the goal of this thesis is to enforce network-wide consensus on top of the IEEE 802.15.4e MAC-protocol standard, Time Slotted Channel Hopping (TSCH); used in research and industrial sensor networks. We present a new system, A2-with-TSCH, integrating the already existing A2 (Agreement in the Air) system to provide consensus primitives on top of the highly reliable MAC-protocol TSCH. We evaluate our A2-with-TSCH system in the Contiki simulator Cooja and on the public testbed FlockLab. The FlockLab evaluation shows that our A2-with- TSCH system reliably reinforces network-wide consensus, while achieving similar performance metrics as the original A2-Synchrotron system.