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Event-to-Sink Reliable Transport in Wireless Sensor Networks

To accomplish this, a reliable transportmechanismis required in addition to robust modulation and media access, link error control and fault tolerant routing. The functionalities and design of a suitable transport solution for WSN are the main issues addressed in this paper. The need for a transport layer for data delivery in WSN was questioned in a recent work [12] under the premise that data flows from source to sink are generally loss tolerant. While the need for end-to-end reliability may not exist due to the sheer amount of correlated data flows, an event in the sensor field needs to be tracked with a certain accuracy at the sink. Hence, unlike traditional. | IEEE ACM TRANSACTIONS ON NETWORKING VOL. 13 NO. 5 OCTOBER 2005 1003 Event-to-Sink Reliable Transport in Wireless Sensor Networks Ozgur B. Akan Member IEEE and Ian F. Akyildiz Fellow IEEE Abstract Wireless sensor networks WSNs are event-based systems that rely on the collective effort of several microsensor nodes. Reliable event detection at the sink is based on collective information provided by source nodes and not on any individual report. However conventional end-to-end reliability definitions and solutions are inapplicable in the WSN regime and would only lead to a waste of scarce sensor resources. Hence the WSN paradigm necessitates a collective event-to-sink reliability notion rather than the traditional end-to-end notion. To the best of our knowledge reliable transport in WSN has not been studied from this perspective before. In order to address this need a new reliable transport scheme for WSN the event-to-sink reliable transport ESRT protocol is presented in this paper. ESRT is a novel transport solution developed to achieve reliable event detection in WSN with minimum energy expenditure. It includes a congestion control component that serves the dual purpose of achieving reliability and conserving energy. Importantly the algorithms of ESRT mainly run on the sink with minimal functionality required at resource constrained sensor nodes. ESRT protocol operation is determined by the current network state based on the reliability achieved and congestion condition in the network. This self-configuring nature of ESRT makes it robust to random dynamic topology in WSN. Furthermore ESRT can also accommodate multiple concurrent event occurrences in a wireless sensor field. Analytical performance evaluation and simulation results show that ESRT converges to the desired reliability with minimum energy expenditure starting from any initial network state. Index Terms Congestion control energy conservation event-to-sink reliability reliable transport protocols wireless .