Section: New Results

Resource management in FUN

Participants : Cristina Cano Bastidas, Valeria Loscri, Simon Duquennoy.

A standard solution for reliable low-power mesh networks was defined in IEEE802.15.4e-2012, through the new MAC layer TSCH. TSCH (Time-Slotted Channel Hopping) provides a globally synchronized network that enables scheduling and channel hopping. Our review paper [28] details the TSCH technology as well as the 6LoWPAN and 6TiSCH protocols. It gathers authors from all major open-source IoT OSes: Contiki, OpenWSN, RIOT and TinyOS. The paper presents architectural considerations when it comes to implementing portable TSCH stacks, and presents preliminary evaluation results.

TSCH networks require global synchronization. The more precise the synchronization, the more energy-efficient the network. We address the challenge of reaching micro-second time synchronization over multiple hops in TSCH networks [31], at low power. The key idea is to use two crystal oscillators, one at low-frequency for low-power timekeeping, one at high-frequency for intra-slot precision. Along with adaptive drift compensation, this method is proven effective through an experimental assessment.

Beaconing is usually employed to allow network discovery and to maintain synchronisation in mesh networking protocols, such as those defined in the IEEE 802.15.4e and IEEE 802.11s standards. Thus, avoiding persistent or consecutive collisions of beacons is crucial in order to ensure correct network operation. Beacons are also used in receiver-initiated medium access protocols to advertise that nodes are awake. Consequently, effective beacon scheduling can enable duty-cycle operation and reduce energy consumption. We propose [56] a completely decentralised and low-complexity solution based on learning techniques to schedule beacon transmissions in mesh networks. We show the algorithm converges to beacon collision-free operation almost surely in finite time and evaluate converge times in different mesh network scenarios.

In [54] we focus on new methods, architectures, and applications for the management of Cyber Physical Objects (CPOs) in the context of the Internet of Things (IoT). The book covers a wide range of topics related to CPOs, such as resource management, hardware platforms, communication and control, and control and estimation over networks. It also discusses decentralized, distributed, and cooperative optimization as well as effective discovery, management, and querying of CPOs. Other chapters outline the applications of control, real-time aspects, and software for CPOs and introduce readers to agent-oriented CPOs, communication support for CPOs, real-world deployment of CPOs, and CPOs in Complex Systems. There is a focus on the importance of application of IoT technologies for Smart Cities.

Finally, we address software security and in particular the challenge of formally verifying the source code of IoT OSes. This is the topic of the yet-to-be-started H2020 VESSEDIA project. Our preliminary study [32] demonstrated the feasibility of applying Frama-C to a memory allocation module of the Contiki OS.