Nouha Baccour (external collaborator, ReDCAD Research Unit, ENIS, Tunisia)
Wireless Sensor Networks (WSNs) are triggering a new era in Information and Communication Technologies. These networks of tiny embedded computing systems are enabling a new set of large-scale monitoring and control applications such as for pervasive Internet, homeland security, critical physical infrastructures monitoring, precision agriculture, environmental monitoring or intelligent transportation systems.
CISTER has been assuming international leadership in the WSNs scientific area, namely on supporting Quality-of-Service (QoS), particularly focusing on timeliness and real-time, reliability and energy-efficiency aspects.
We are addressing the use of both standard and COTS technology and cutting-edge solutions designed from scratch. CISTER pursues excellence-level collaborative R&D sustained by analytical, simulation and experimental models. We have recently designed, implemented and deployed the largest WSN test-bed in Europe to date, with 300+ sensor nodes.
On Going Research
CISTER researchers are world leaders on IEEE 802.15.4 and ZigBee technologies (ART-WiSe). We have provided methodologies to analyze, dimension and engineer WSNs with improved QoS and the open-ZB toolset has been made publicly available (over 100000 visits and 6000 downloads - average 4-5 downloads per day). It includes: (i) the implementation of the IEEE 802.15.4 protocol in TinyOS, for the MICAz and TelosB motes; (ii) the implementation of the ZigBee Network Layer for supporting synchronized multiple cluster topologies (the Cluster-Tree topology) in TinyOS, for the TelosB motes; (iii) simulation models of the IEEE 802.15.4 and ZigBee protocols in OPNET; (iv) a MATLAB tool for timing analysis and network dimensioning, based on Network Calculus. This framework triggered the creation of the TinyOS 15.4 and ZigBee Working Groups, in which CISTER researchers have been actively involved.
In what respects WSN research within the CONET NoE, CISTER is leading the COTS4QoS and participating in the RMA research cluster. In COTS4QoS we are essentially interested on enabling/improving different QoS properties in WSNs using standard and COTS technologies as a baseline. RMA focuses on resource management and adaptation in WSNs and BSNs, addressing radio diversity, interference modelling and link quality estimation.
CISTER researchers have been doing cutting edge research on radio interference and link quality estimation, which is a basic building block for supporting higher level protocols and mechanims such as routing, mobility management, fault-tolerance, deployment and topology control. We have proposed an innovative link quality estimator (LQE) based on Fuzzy Logic (F-LQE) that shows significant benefits over existing ones and the RadiaLE benchmarking toolset for the performance evaluation of LQEs, available as an open-source. Within this framework, the EWSN/CONET MSc Thesis Award 2011 was co-supervised by a CISTER researcher.
CISTER researchers have also been fostering research work on Hexagonal WSNs, in which nodes are logically connected to six peer neighbor nodes. This network model enables simple and low-overhead protocols, which are very atractive from the point of view of resource constrained WSNs and bounded end-to-end communication delays (for fulfilling real-time requirements).
Another paradigmatic example on how CISTER aims at pushing the state-of-the-art in WSNs is on building a real-world deployment with 10000 nodes (one order of magnitude higher that the largest WSN deployed so far), within the context and timeframe (3 years) of the EMMON project, lead by Portuguese hi-tech company Critical Software. Within this project we have been designing a scalable and hierarchical WSN architecture coping with QoS properties such as timeliness and scalability. The EMMON consortium recently presented a live demonstration of an integrated system prototype at ISEP, a monitoring application encompassing all system components, ranging from hardware, communication architecture, middleware and command and control GUI. This was instantiated in a WSN deployment of over 300 sensor nodes - TOBK the largest WSN test-bed in Europe so far.
In what concerns application-driven R&D, we highlight the work on using WSNs for structural health monitoring (under a collaboration with ISISE), for energy-efficient data centres (under the SENODS project) and for energy-efficient buildings (under the EMMON and more recently under the ENCOURAGE projects).
Projects & Leadership
We are one of the leading partners in the EMMON project, within the Artemis programme. CISTER leads WP4 “Research on Protocols & Communication Systems” and several tasks related to the specification of the WSN architecture and the design of time and energy-efficient data aggregation and resource allocation mechanisms.
CISTER is a core partner in the European Network of Excellence on Cooperating Objects (CONET). Under CONET and more related to the WSN area, we are leading the COTS4QoS (QoS provision using COTS) and participating in the RMA (resource management and adaptation) research cluster.
More recently, we started researching on the use of WSNs for energy-efficient data centres and buildings, under the SENODS (PT-CMU) ENCOURAGE (ARTEMIS) projects, respectively.
We are leading FCT funded projects REWIN and MASQOTS. In REWIN where we aim at developing methods to offer real-time guarantees to individual real-time flows over multi-hop WSN of arbitrary node deployments and arbitrary traffic pattern.MASQOTS addresses the support of physical mobility in WSNs under reliability and timeliness constraints.
Guest editors of a Special Section on "From Embedded Systems to Cooperating Objects" of the IEEE Transactions on Industrial Informatics, under preparation.
Organization of the International Workshop on Real Time Networks (RTN'08) and the International Workshop on Cyber-Physical Systems Challenges and Applications (CPS-CA'09). Co-organization of the SensorNets'09 school.
Tutorial at the Intenational CONET Summer School, "Distributed Data Storage, Dissemination and Processing", Bertinoro, Italy, July 2009.
EWSN 2009 Award Best MSc Thesis: On the use of IEEE 802.15.4/ZigBee for Time-Sensitive Wireless Sensor Network Applications.
Tutorial at the 6th European Conference on Wireless Sensor Networks (EWSN'09), Cork, Ireland, February 2009 (slides available).
- The ECRTS'06 paper improves the bandwidth utilization of the contention-free period (CFP) in the IEEE 802.15.4 superframe, by proposing a methodology (i-GAME) for allowing several nodes to share a GTS (selected among 4 best papers for a journal publication);
- In the ECRTS'07 paper (Best Paper Award) we proposed a solution to efficiently schedule beacons/superframes in ZigBee cluster-tree networks (TDBS) in a way to avoid inter-cluster collisions;
- Our MASS'07 paper proposes the open-ZB open-source implementation of the IEEE 802.15.4/ZigBee protocol stack on TinyOS (selected as one of the 12 extended papers out of 265 submissions); we have recently presented the most recent official TinyOS implementation at the poster session of EWSN 2011.
- Ricardo Severino MSc Thesis ('EWSN/CONET’09 Best Master Thesis Award') proposes a very simple but extremely effective solution (H-NAME) for mitigating the hidden-node problem in WSNs, namely in IEEE 802.15.4/ZigBee-based WSNs; also published in the IEEE Transactions on Industrial Informatics;
- In ETFA '09, we propose and experimentally validate a distributed algorithm for logical Hexagonal WSN topology formation;
- The ACM TOSN 2010 paper is the corollary of our work on worst-case analysis and dimensioning of cluster-tree WSNs, building upon the RTSS'06 (static sink, located in the root) and RTCSA'08 (mobile sink, located in any router) papers;
- The EWSN'10 paper presents an innovative link quality estimator based on Fuzzy Logic (F-LQE), improving on existing ones, as earlier identified by simulation in the MASCOTS'09 paper. F-LQE This was extensively tested and validated through both simulation and experimentation, building upon RadiaLE - an open-source benchmarking testbed for the performance evaluation of LQEs. RadiaLE was recently published at the Elsevier Ad-Hoc Networks Journal (see here). A survey paper on LQE will be soon published in the ACM Transactions on Sensor Networks
- The EWSN'11 paper on "BANMAC: opportunistic packet scheduling in body area networks" proposes a scheme for body sensor nodes (placed in different body locations) to select transmission timings according to RSS fluctuations resulting from body movement.
The members of the CISTER WSN team have been publishing tens of highly cited papers in top-notch journals (e.g. ACM Transactions on Sensor Networks, Elsevier Ad-Hoc Networks Journal, Real‐Time Systems Journal, IEEE Transactions on Industrial Informatics) and conferences (e.g. EWSN, IEEE MASS, ACM/IEEE IPSN, IEEE RTSS, ECRTS, IEEE RTCSA). Some of our papers have over 10 citations per year.
A list of publication targets which we consider relevant within our research areas is available here.