The aim of a Wireless Sensor Network is to send queries to the sensor nodes in the area of interest and transmit collected data to the sink. The connectivity between the target sensor nodes and their sink should be preserved as much as possible. The most energy depletion operation, performed by battery-limited sensor nodes is the data transmission. In order to extend connectivity, this operation should be limited. In this paper we propose an optimal message aggregation model, that reduces the number of packets injected to the network. Also, a hop by hop error recovery mechanism is presented. The mechanism enables the immediate sender to change the packet's route dynamically when its parent on the path is down, in a tree type sensor network. A mathematical analysis of network lifetime as a measure of number of messages transmitted to sink is given. The analysis is extended to show the impact of in network buffering on the network lifetime which is defined as reliability. It has been shown that optimized buffering improves network lifetime by a factor of message count in a single network packet. Numerical results of the analysis have also been obtained for a simplified reliability and aggregation model.

Proceedings of Second International Workshop on Sensor and Actor Network Protocols and Applications (SANPA 2004), Boston, USA
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