Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Sprout is an end-to-end transport protocol for interactive applications that desire high throughput and low delay. Sprout works well over cellular wireless networks, where link speeds change dramatically with time, and current protocols build up multi-second queues in network gateways. Sprout does not use TCP-style reactive congestion control; instead the receiver observes the packet arrival times to infer the uncertain dynamics of the network path. This inference is used to forecast how many bytes may be sent by the sender, while bounding the risk that packets will be delayed inside the network for too long. In evaluations on traces from four commercial LTE and 3G networks, Sprout, compared with Skype, reduced self-inﬂicted end-to-end delay by a factor of 7.9 and achieved 2.2 the transmitted bit rate on average. Compared with Google’s Hangout, Sprout reduced delay by a factor of 7.2 while achieving 4.4 the bit rate, and compared with Apple’s Facetime, Sprout reduced delay by a factor of 8.7 with 1.9 the bit rate. Although it is end-to-end, Sprout matched or outperformed TCP Cubic running over the CoDel active queue management algorithm, which requires changes to cellular carrier equipment to deploy. We also tested Sprout as a tunnel to carry competing interactive and bulk trafﬁc (Skype and TCP Cubic), and found that Sprout was able to isolate client application ﬂows from one another.
DepartmentMassachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory; Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Proceedings of the 10th USENIX Symposium on Networked Systems Design and Implementation (NSDI ’13)
Winstein, Keith, Anirudh Sivaraman and Hari Balakrishnan. "Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks." 10th USENIX Symposium on Networked Systems Design and Implementation, NSDI '13, April 2-5, 2013, Lombard, IL. 2013.
Author's final manuscript