رسائل دكتوراة
English
2018
Boostin Wireless Sensor Network communications quality for Smart Grid Applications
Mohamed Jmaiel, Sana Rekik
المدرسة الوطنية للمهندسين - صفاقس-جامعة صفاقس · تونس
Wireless Sensor Networks (WSNs) have been recognized as a promising communication technology for the Internet of Things (IoT). In particular, smart grids, the next generation of traditional electric grids, rely on WSNs for enabling pervasive monitoring and control of the electric network. How-ever, the deployment of WSNs in smart grids brings new challenges, mainly (i.) the unreliability of low-power links due to the harsh electric grid environ-ments (electromagnetic interference, obstructions, electric equipment's noise,etc.), (ii.) the di erent and often contradicting communication requirements, especially in terms of reliability and latency/delay, and (iii.) the diverse co-habiting communication technologies that raise interoperability issues. Due to these challenges, conventional WSN protocols are not sufficiently adequate for smart grid applications and several research
efforts were devoted to their optimization. Unfortunately, none of the existing optimized WSN protocols addresses all the emerged challenges at once. Therefore, efficient/enhanced communications protocols are still required for a successful deployment of WSNs in smart grid applications. The objective of this dissertation is to enhance WSN communication qual-ity in order to address all the emerged challenges from the application of WSNs in smart grids. We rst provide a comprehensive survey on WSN communications in smart grids. For instance, we propose a taxonomy of re-lated works and we discuss the still-open issues. Especially, we show that WSN-based smart grid applications still require efficient protocols at the dif-ferent communication layers. On the other hand, we realize that the IoT protocol stack represents a promising communication solution for WSN ap-plications in smart grids. For instance, it promises high interoperability with IP-based smart grid networks, as it is composed of a set of open standards. However, it presents some open issues to be resolved with respect to WSN-based smart grid applications. These issues mainly concerns the routingand the MAC layers of the stack, running the RPL (IPv6 Routing Protocol for Low Power and Lossy Networks) and the TSCH (Time Slotted Channel Hopping) protocols, respectively. The RPL protocol su ers from unreliability issues caused by the selection of routing paths involving unreliable links. To overcome this problem, routing paths have to be selected based on accurate link quality information. Thus,we propose an accurate link quality estimator that is able to capture thereal status of low power links in harsh smart grid environments. Then, we design a novel routing metric for RPL, called Opt-FLQERM, that allows delivering data over paths composed of high quality links. Simulation results demonstrate that Opt-FLQERM improves the RPL performance in terms of end-to-end reliability, compared to traditional routing metrics (including the RPL default metric). As for the TSCH MAC protocol, the TSCH speci cation does not de nea practical solution for the establishment of the schedule and does not sup-port the
differentiation of the traffic. Thus, we propose e-TSCH-Orch, an enhanced Orchestra-based TSCH protocol, that minimizes the end-to-endcommunication delay, through the consideration of traffic profiles in time slots assignment. It also accounts for packet criticality levels and supports traffic differentiation. A thorough performance analysis, based on both sim-ulation and real experiments, shows that e-TSCH-Orch improves the end-to-end communication delay and favors the delivery of high priority traffic over low priority traffic.