DISAGREE: disagreement-based querying in wireless sensor networks

Traditional data acquisition methods for wireless sensor networks (WSNs) require all sensor nodes to transmit at least once to the sink node to obtain a full view of the network. In this paper we present Disagree, a different data acquisition method to retrieve data in WSNs that works in the opposite way as compared with traditional methods. In Disagree, only nodes that do not satisfy an assertion are required to transmit data back to the sink node in order to obtain a complete view of the network. We show that this behavior is the base of an energy-efficient way to gather all data. An important feature of Disagree is that it saves energy at the sensor level by exploiting data correlation. Rather than requesting explicit data readings from all sensor nodes, Disagree estimates the readings from sensor nodes that did not respond to the assertion. As a result of this policy, Disagree can obtain a view of the sensing field with different levels of resolution involving the transmission of only a subset of the sensor nodes by exploiting spatial data redundancy. We implemented Disagree in NS-2 network simulator and results indicate Disagree can significantly reduce the percentage of nodes replying to queries compared with flat and a cluster head based approaches.