Optimal multicast smoothing of streaming video over the Internet

Subhabrata Sen, Don Towsley, Zhi Li Zhang, Jayanta K. Dey

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


A set of applications such as Internet video broadcasts, corporate telecasts, and distance learning require the simultaneous streaming of video to a large population of viewers across the Internet. The high bandwidth requirements and the multitimescale burstiness of compressed video make it a challenging problem to provision network resources for streaming multimedia. For such applications to become affordable and ubiquitous, it is necessary to develop scalable techniques to efficiently stream video to a large number of disparate clients across a heterogeneous internet. In this paper, we propose to multicast smoothed video over an application-level overlay network of proxies, and to differentially cache the video at the intermediate nodes (proxies) in the distribution tree, in order to reduce the network bandwidth requirements of video dissemination. We formulate the multicast smoothing problem as an optimization problem, and develop an algorithm for computing the set of transmission schedules for the tree that minimize the peak rate and rate variability, given buffer constraints at different nodes in the tree. We also develop an algorithm to compute the minimum buffer allocation in the entire tree, such that feasible transmission to all the clients is possible, when the tree has heterogeneous rate constraints. We show through trace-driven simulations that substantial benefits are possible from multicast smoothing and differential caching, and that these gains can be realized even with modest proxy caches.

Original languageEnglish (US)
Pages (from-to)1345-1359
Number of pages15
JournalIEEE Journal on Selected Areas in Communications
Issue number7
StatePublished - Sep 2002

Bibliographical note

Funding Information:
Manuscript received February 15, 2002. The work at the University of Massachusetts was supported in part by the National Science Foundation (NSF) under Grant NCR-9523807, Grant NCR-9508274, and Grant CDA-9502639. The work of Z.-L. Zhang was supported in part by the University of Minnesota Graduate School under a Grant-in-Aid Grant, and in part by the NSF under CAREER Award Grant NCR-9734428 and Grant NSF ANI 9903228. The work of S. Sen and J. K. Dey was performed when they were at the University of Massachusetts, Amherst, MA 01003 USA. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the funding agencies. This paper was presented in part at the IEEE Infocom Conference, New York, NY, March 1999.


  • Bandwidth smoothing
  • Differential caching
  • Multicast distribution tree
  • Multimedia communication
  • Multimedia proxy
  • Multimedia systems
  • Overlay networks
  • Variable-bit-rate video


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