Connected coverage with rapid forwarding in energy harvesting wireless sensor networks for critical rare events

To ensure event detection and subsequent rapid forwarding of notification messages, wireless sensor networks deployed to detect critically important rarely occurring events must maintain both sensing coverage and low latency network connectivity at all times. Maintaining coverage for extended periods is relatively straight forward as passive sensing components tend to consume little energy. Maintenance of network connectivity, however, requires sensing devices constantly supply power to their transceivers, significantly reducing the longevity of the sensor network. Energy harvesting can extend the operational life of sensing devices with always on transceivers, potentially to the point where they can operate year round. In addition, over populating the sensing area with more devices than are required to provide complete sensing cover introduces the possibility of self-organisation where sensing devices agree amongst themselves which will remain active and which will be allowed to sleep. Few algorithms have been proposed to address both coverage and forwarding; those that do are either unconcerned with rapid propagation or have not been optimised to handle the constant changes in topology observed in duty cycling networks. This thesis first analyses the energy consumption profiles of commercially available wireless sensing devices then presents mechanisms by which these devices can both maintain sensing coverage and rapidly forward event detection messages delayed only by the inherent latencies found in wireless multi-hop networks. These individual contributions form the basis of a combined algorithm for Coverage Preservation with Rapid Forwarding (CPRF). Through evaluations including live deployment, CPRF is shown to deliver perfect coverage maintenance and low latency message propagation whilst allowing stored-charge conservation via collaborative duty cycling in energy harvesting networks