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

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. 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. 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.