文摘
WSN is a dynamic network of randomly deployed tiny sensor nodes to monitor the physical ambient conditions, healthcare services, military surveillance, movements and tracking of vehicles or other targets etc. Sensing generates continuous streams of data which are distributed throughout the network. This distributed data is retrieved by various applications through numerous appropriate means. Query based retrieval method is the most popular general purpose method for data extraction. In response to queries injected into the network nodes communicate data among themselves or to the base-station. Communication traffic thus generated is highly energy consuming activity. It drains out limited energy available with a node thereby rendering it useless as replenishment of energy is not possible in most of the deployments therefore efficient use of energy is the main focus to prolong the life of a WSN. Reduction of communication traffic is the most effective mean to achieve energy efficiency. In this paper we have proposed an approach towards this end which employs optimization of multiple queries at the base station and data compression at individual nodes resulting in quantitative reduction in communication traffic. Quality of data is not compromised in the process. Keywords Wireless sensor network (WSN) Query optimization In-network optimization Base-station optimization Epoch