Guaranteeing statistical QoS to regulated traffic: the single node case

Multimedia traffic can typically tolerate some loss but has rigid delay constraints. A natural QoS requirement for a multimedia connection is a prescribed bound on the the fraction of traffic that exceeds an end-to-end delay limit. We propose and analyze a traffic management scheme which guarantees QoS to multimedia traffic while simultaneously allowing for a large connection-carrying capacity. We study our traffic management scheme in the context of a single node. In order for the node to guarantee QoS, each connection´s traffic is regulated. In order to support many connections, the link statistically multiplexes the connections´ traffic. The scheme consists of (i) cascaded leaky-buckets for traffic regulation, (ii) smoothers at the ingresses, and (iii) bufferless statistical multiplexing within the node. For this scheme we show that loss probabilities are minimized with simple one-buffer smoothers which operate at specific minimum rates. We also show that the worst-case input traffic is extremal on-off traffic for all connections. These two results lead to a straightforward scheme for guaranteeing QoS to regulated traffic. Using MPEG video traces, we present numerical results which demonstrate the methodology. Finally, we compare the bufferless scheme with buffered statistical multiplexing