On Combining Duty-cycling with Network Coding in Flood-based Sensor Networks

Network coding and duty-cycling are two popular techniques for saving energy in wireless sensor networks. To the best of our knowledge, the idea to combine these two techniques, for even more aggressive energy savings, has not been explored. One explanation is that these two techniques achieve energy efficiency through conflicting means, e.g., network coding saves energy by exploiting overhearing, whereas dutycycling saves energy by cutting idle listening and, thus, overhearing. In this thesis, we thoroughly evaluate the use of network coding in duty-cycled sensor networks. We propose a scheme called DutyCode, in which a MAC protocol implements packet streaming and allows the application to decide when a node can sleep. Additionally, a novel, efficient coding scheme decision algorithm, ECSDT, assists DutyCode to reduce further energy consumption by minimizing redundant packet transmissions, while an adaptive mode switching algorithm allows smooth and timely transition between DutyCode and the default MAC protocol, without any packet loss. We investigate our solution analytically, implement it on mote hardware, and evaluate it in a 42-node indoor testbed. Performance evaluation results show that our scheme saves 30-46% more energy than solutions that use network coding, without using duty-cycling

To overhear or not to overhear: a dilemma between network coding gain and energy consumption in multi-hop wireless networks

Any properly designed network coding technique can result in increased throughput and reliability of multi-hop wireless networks by taking advantage of the broadcast nature of wireless medium. In many inter-flow network coding schemes nodes are encouraged to overhear neighbour’s traffic in order to improve coding opportunities at the transmitter nodes. A study of these schemes reveal that some of the overheard packets are not useful for coding operation and thus this forced overhearing increases energy consumption dramatically. In this paper, we formulate network coding aware sleep/wakeup scheduling as a semi Markov decision process (SMDP) that leads to an optimal node operation. In the proposed solution for SMDP, the network nodes learn when to switch off their transceiver in order to conserve energy and when to stay awake to overhear some useful packets. One of the main challenges..

Opportunistische Weiterleitung von netzwerkcodierten Multicast-Übertragungen in drahtlosen Sensornetzen

In dieser Dissertation wird ein Kommunikationsschema für drahtlose Sensornetze entwickelt, welches die Multicast-Kommunikation unterschiedlicher Anwendungen mittels Netzwerkcodierung überlagert. Eine besondere Herausforderungen stellen hierbei die Eigenschaften drahtloser Sensornetze dar. Die eingeschränkte Netzwerkkapazität beschränkt zugleich das erreichbare Maximum der handhabbaren Datenmenge