Real-time Communication over Cluster-tree Wireless Sensor Networks
Ref: HURRAY-TR-101001 Publication Date: 5, Oct, 2010
Real-time Communication over Cluster-tree Wireless Sensor NetworksRef: HURRAY-TR-101001 Publication Date: 5, Oct, 2010
Modelling and simulation of the fundamental performance limits of Wireless Sensor Networks (WSNs) is of paramount importance to understand their behaviour under the worst-case conditions and to make the appropriate design choices. This is particular relevant for time-sensitive WSN applications, where the timing behaviour of the network protocols impacts on the correct operation of these applications. Furthermore, energy efficiency is a key requirement to be fulfilled in these applications since the wireless nodes are usually battery-powered. In that direction this thesis contributes with an accurate simulation model of the IEEE 802.15.4/ZigBee protocols and an analytical methodology for the worst-case analysis and dimensioning of a static or even dynamically changing cluster-tree WSN where the data sink can either be static or mobile. The thesis is focused on the study of WSNs with cluster-tree topology because it supports predictable and energy efficient behaviour, which is suited for time-sensitive applications using battery-powered nodes. On the other side, in contrast with the star and mesh topologies, the cluster-tree topology expresses several challenging and open research issues such as a precise cluster scheduling to avoid inter-cluster collisions (messages/beacons transmitted from nodes in different overlapping clusters). Hence, the next objective is to find the collision-free periodic schedule of clusters' active portions, called Time Division Cluster Schedule (TDCS), while minimizing the energy consumption of the nodes and meeting all data flows' parameters. The thesis also shows how to apply the proposed methodologies to the specific case of IEEE 802.15.4/ZigBee beacon enabled cluster-tree WSNs, as an illustrative example that confirms the applicability of general approach for specific protocols. Finally, the validity and accuracy of the simulation model and methodologies are demonstrated through the comprehensive experimental and simulation studies. Using the proposed analytical methodologies and simulation model, system designers are able to easily configure the IEEE 802.15.4/ZigBee cluster-tree WSN for a given application-specific Quality of Service (QoS) requirements prior to the network deployment.
PhD Thesis, Faculty of Electrical Engineering, Czech Technical University in Prague.