Cross-layer data collection in wireless sensor networks

Energy efficiency is a fundamental requirement in many Wireless Sensor Network (WSN) applications due to the limited battery power of sensor nodes and the difficulty associated with replenishing such source. As a result, significant research efforts have been pursued over the last decade to realize energy efficient distributed data collection techniques aimed at prolonging network lifetime. Within data collection applications, there is a class of applications that do not reconstruct the entire sensing field but mainly focus on monitoring and event/anomaly detection scenarios. In such applications, only representative data values (or distinct within a given threshold) are desired from different geographical (spatial) regions. Utilizing existing data collection techniques in this type of applications yields communication-inefficient solutions, and therefore expensive in terms of energy cost. In this talk, we study cross-layer data collection/monitoring and highlight a cross-layer framework to reduce the number of communication operations in such applications. We propose the use of overhearing at the Medium Access Control (MAC) layer in modifying the behavior of the application layer in each node to realize efficient data collection. Data redundancy is reduced by dynamically distributing cluster head responsibilities over cluster members, thus balancing the load and prolonging the network lifetime. Despite the cost of overhearing, it can be overcome by the potential reduction of the number of communication operations by a factor of up to N-1 where N is the number of nodes in a neighborhood.