Abstract
In this paper, we consider a proportional delay model far Internet differentiated services. Under this model, art 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 i traffic relative to that of class i - 1 traffic is consistently a specifiable ratio. If the ratio is less than one, the ISP can legitimately charge users of class i traffic a higher tariff rate (compared to the rate for class i - 1 traffic), since class i users consistently enjoy better performance than class i - 1 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 efficiency control algorithm. Experiments are carried out to illustrate the short-term, medium-term and long-term relative waiting time performances for different service classes.