A scheduling algorithm for relative delay differentiation

An important issue in the design of multi-service IP networks is to find appropriate mechanisms to provide different levels of quality of service (QoS) for different types of applications. In this paper, scheduling mechanisms for real-time traffic in a differentiated services IP network are studied. A new scheduling algorithm called weighted earliest due date (WEDD) is proposed that provides tunable delay differentiation for real-time applications like voice over IP. WEDD is an enhancement of the earliest due date (EDD) scheduler in the sense that not only different deadlines but also different deadline violation probabilities are provided. The ratios of the violation probabilities are directly defined by a set of parameters. Simulation studies are performed to show that the scheduler is able to maintain the specified ratios under various load conditions.