Do twin clouds make smoothness for transoceanic video telephony?

Jian Li, Zhenhua Li, Yao Liu, Zhi Li Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Transoceanic video telephony (TVT) over the Internet is challenging due to 1) longer round-trip delay, 2) larger number of relay hops, and 3) higher packet loss rate. Real-world measurements of Skype, Face time, and QQ confirm that their TVT service quality is mostly unsatisfactory. Recently, when using We Chat to make transoceanic video calls, we are fortunate to find that it achieves stably smooth TVT. To explore how this is possible, we conduct in-depth measurements of We Chat data flow. In particular, we discover that the service provider of We Chat deploys a novel, specially designed 'twin clouds' based architecture to deliver transoceanic (UDP) packets. Thus, data delivery between two callers is no longer point-to-point (used by Skype, Face time, and QQ) over the best-effort Internet. Instead, transoceanic video packets are delivered through the privileged backbone formed by twin clouds, which greatly reduces the round-trip delay, number of relay hops, and packet loss rate. Besides, whenever a packet is found lost, multiple duplicate packets are instantly sent to aggressively make up for the loss. On the other hand, we notice two-fold shortcomings of twin clouds. First, due to the sophisticated resource provisioning inside the twin clouds, the video start up time is considerably extended. Second, due to the high cost of deploying twin clouds, the capacity of the privileged backbone is limited and sometimes in shortage, and thus We Chat has to deliver data via a detour path with degraded performance. Ultimately, we believe that the twin clouds based data delivery solution will arouse a new direction of Internet video telephony research while still deserves optimization efforts.

Original languageEnglish (US)
Title of host publicationProceedings - 2015 44th International Annual Conference on Parallel Processing, ICPP 2015
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages10
ISBN (Electronic)9781467375870
StatePublished - Dec 8 2015
Event44th International Conference on Parallel Processing, ICPP 2015 - Beijing, China
Duration: Sep 1 2015Sep 4 2015

Publication series

NameProceedings of the International Conference on Parallel Processing
ISSN (Print)0190-3918


Other44th International Conference on Parallel Processing, ICPP 2015

Bibliographical note

Funding Information:
This work is supported by the High-Tech Research and Development Program of China ("863 China Cloud" Major Program) under grant 2015AA01A201, China NSF under grant 61471217, and China Postdoctoral Science Fund under grant 2014M550735. Zhi-Li Zhang is supported in part by US NSF under grants CNS-1117536 and CNS-1411636, and US DoD ARO MURI Award W911NF-12-1-0385.

Publisher Copyright:
© 2015 IEEE.


  • Cloud computing
  • Transoceanic video telephony
  • Video Smoothness


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