Reliable Data Aggregation for Real-Time Queries in Wireless Sensor Systems

Reliable Data Aggregation for Real-time Queries in Wireless Sensor Systems Kam-Yiu Lam, Henry C.W. Pang, Sang H. Son and BiYu Liang Email: [email protected], [email protected], [email protected], [email protected] Department of Computer Science City University of Hong Kong 83 Tat Chee Avenue, Kowloon HONG KONG Department of Computer Science University of Virginia Charlotte, Virginia USA Abstract In this paper, we study the reliability issue in aggregating data versions for execution of real-time queries in a wireless sensor network in which sensor nodes are distributed to monitor the events occurred in the environment. The execution of a real-time query needs to meet the deadline of the query as well as the result interval requirement to improve the reliability of the query results. In this paper, we extend the Parallel Data Shipping with Priority Transmission (PAST) scheme to be workload sensitive (the new algorithm is called PAST with Workload Sensitivity (PAST-WS)) in selecting the coordinator node and the paths for transmitting the data from the participating nodes to the coordinator node. PAST-WS considers the workload at each relay node to minimize the total cost and delay in data transmission. The simulation results show that PAST-WS not only reduces the data aggregation cost significantly, but also distributes the aggregation workload more evenly among the nodes in the system. Both properties are very important for extending the lifetime of sensor networks since the energy consumption rate of the nodes highly depends on the data transmission workloads.