Complex events are very useful in
radio frequency identification
) applications. Even though many techniques have been proposed to detect RFID complex event instances online, they do not support online pattern aggregation operations. In this paper, we present an online pattern aggregation algorithm, named
divides a sliding window into several sub-windows and computes its aggregation value from those of its sub-windows. Based on the distribution characteristics of RFID data streams, we design different mapping functions to dispatch events to related sub-windows. Finally, our extensive experiments demonstrate that
is effective and efficient.