Joint position estimation, packet routing and sleep scheduling in wireless sensor networks

Abstract

Wireless Sensor Network (WSN) is an important research field in Computer Science with applications that span multiple domains. Due to the limitation of sensor nodes, network lifetime is a critical issue that needs to be addressed. Therefore, in this thesis I propose the Energy-aware Connected k-Neighbourhood (ECKN), a joint position estimation, packet routing, and sleep scheduling solution that combines some overlap- ping features. I propose a localization algorithm that performs trilateration using the position of a mobile sink and of neighbour nodes to estimate the position of a sensor node with no GPS module. I introduce a routing protocol based on the well-known Greedy Geographic Forwarding (GGF). Similarly to GGF, my protocol takes into consideration the position of neighbours to decide the best forwarding node, however it also considers the residual energy in order to guarantee that the forwarding node will deliver the packet. The concept of bridges is also introduced, in which the sink compares its current position with previous positions and calculates whether there is a shortest path in order to create a bridge that will reduce the number of hops a packet has to travel through. Lastly, a sleep scheduler is proposed in order to extend the network lifetime, it is based on the Connected k-Neighbourhood (CKN) algorithm, which aids in the decision of what nodes goes to sleep while maintaining the network connected. My sleep scheduler maintains the network denser in the area close to the sink, since this region receives packets from the whole network to forward to the sink. An extensive set of performance evaluation experiments is conducted and results show that ECKN can extend network lifetime, while sustaining acceptable packet delivery ratio and reducing network overhead.