Characterization and Performance Evaluation for Proportional Delay Differentiated Services

In this paper, we consider a proportional delay model for Internet differentiated services. Under this model, an ISP can control the “spacing” of waiting times between different classes of traffic. Specifically, the ISP tries to ensure that the average waiting time of class traffic relative to that of class traffic is consistently a specifiable ratio. If the ratio is less than one, the ISP can legitimately charge users of class traffic a higher tariff rate (compared to the rate for class traffic), since class users consistently enjoy better performance than class users. We use time-dependent priority scheduling to realize the proportional delay model. We formally characterize the feasible regions in which given delay ratios can be achieved. Moreover, a set of scheduling parameters for obtaining the desired delay ratios can be determined by an efficient control algorithm. Experiments are carried out to illustrate the short-term, medium-term and long-term relative waiting time performances for different service classes.