Aggregation of heavy-tailed on-off flows is multifractal

We show that the aggregation of heavy-tailed on-off flows can exhibit multifractality in nature in addition to the well-known long-range dependency. Justifications are provided through analyzing the power density spectrum of a single on-off flow, calculating the multifractal spectrum of aggregated flows, and measuring the distributions of the increment process. Effects of the on and the off period on the multifractal behavior are examined. With a new understanding of the on-off model taking into account the TCP window-based control mechanism, possible roles of the TCP window size and the RTT in producing multifractal traffic are suggested.