Comparison of Scheduling Policies for Delay-sensitive and Loss-sensitive Traffic

The queueing disciplines are reviewd in the context of two different characteristics of traffic sources: delay-sensitive (real-time) traffic and loss-sensitive traffic. Integration of traffic types is one of the important features in Broadband ISDN. Therefore the scheduling discipline used to multiplex that integrated traffic is also expected to be intelligent enough to handle them according to their different QOS (quality-of-service) requirements. For instance, while traffic such as voice and video requires to be trasmitted fast, i.e., small delays in transmission, traffic such as data requires semantic accuracy, i.e., low packet loss. Appropriate scheduling policies for this type of network discriminate the incoming packets based on the service class rather than the relative arrival times or the required service times. Weighted Round-Robin queueing, Fair queueing and packet-by-packet Generalized Processor Sharing queueing disciplines are discussed in relation to these ideas