A. Mavromatis, G. Papadopoulos, X. Fafoutis, A. Goulianos, G. Oikonomou, P. Chatzimisios, T. Tryfonas, "Link quality and path based clustering in IEEE 802.15.4-2015 TSCH networks", in Proc. IEEE ISCC, pp. 798-803, 2017
Advance clustering techniques have been widely used in Wireless Sensor Networks (WSNs) since they can potentially reduce latency, improve scheduling, decrease end-to-end delay and optimise energy consumption within a dense network topology. In this paper, we present a novel clustering algorithm for high density IEEE 802.15.4-2015 Time-Slotted Channel Hopping (TSCH). In particular, the proposed methodology merges a variety of solutions into an integrated clustering design. Assuming an homogeneous network distribution, the proposed configuration deploys a hierarchical down-top approach of equally numbered sub-groups, in which the formation of the separate sub-groups is adapted to the network density and the node selection metric is based on the link quality indicator. The presented algorithm is implemented in Contiki Operating System (OS) and several test vectors have been designed in order to evaluate the performance of the proposed algorithm in a COOJA simulation environment. Performance results demonstrate the capability of the clustering structure since compared to the default scheme it significantly improves the energy efficiency up to 35%, packet drops more than 40% as well the packet retransmission rate. Last but not least, the outcome of this study indicates a major increase in the network lifetime, i.e., up to 50%.
G. Papadopoulos, V. Kotsiou, A. Gallais, G. Oikonomou, P. Chatzimisios, T. Tryfonas, T. Noël, "A Mobility-Supporting MAC Scheme for Bursty Traffic in IoT and WSNs", in Proc. IEEE GLOBECOM, 2016
Recent boom of mobile applications has become an essential class of mobile Internet of Things (IoT), whereby large amounts of sensed data are collected and shared by mobile sensing devices for observing phenomena such as traffic or the environmental. However, most of the existing Medium Access Control (MAC) protocols mainly focus on static networks. Thus, mobile sensor nodes may pose many communication challenges during the design and development of a MAC protocol. These difficulties first require an efficient connection establishment between a mobile and static node, and then an effective data packet transmissions. In this study, we propose MobIQ, a MAC scheme that allows an advanced mobility-handling scheme for low-power MAC protocols, which allows for efficient neighbour(hood) discovery and low-delay communication. Our thorough performance evaluation, conducted on top of Contiki OS, shows that MobIQ outperforms state-of-the-art solutions such as MoX-MAC, MOBINET and ME-ContikiMAC, in terms of reducing both delay, contention to the medium and energy consumption.
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