Performance of TCP-friendly streaming sessions in the presence of heavy-tailed elastic flows

Abstract

We consider a fixed number of streaming sessions which share a bottleneck link with a dynamic population of elastic flows. Motivated by extensive measurement studies, we assume that the sizes of the elastic flows exhibit heavy-tailed characteristics. The elastic flows are TCP-controlled, while the transmission rates of the streaming applications are governed by a so-called TCP-friendly rate control protocol. TCP-friendly rate control protocols provide a promising mechanism for avoiding severe fluctuations in the transmission rate, while ensuring fairness with competing TCP-controlled flows. Adopting the processor-sharing (PS) discipline to model the bandwidth sharing, we investigate the tail distribution of the deficit in service received by the streaming sessions compared to a nominal service target. The latter metric provides an indication for the quality experienced by the streaming applications. The results yield valuable qualitative insight into the occurrence of persistent quality disruption for the streaming users. We also examine the delay performance of the elastic flows by exploiting a useful relationship with a processor-sharing queue with permanent customers.