Improving the Performance of Reliable Transport Protocols in Mobile Computing Environments
We explore the performance of reliable data communication in mobile computing environments. Motion across wireless cell boundaries causes increased delays and packet losses while the network learns how to route data to a host’s new location. Reliable transport protocols like TCP interpret these delays and losses as signs of network congestion. They consequently throttle their transmissions, further degrading performance. We quantify this degradation through measurements of protocol behavior in a wireless networking test bed. We show how current TCP implementations introduce unacceptably long pauses in communication during cellular handoffs (800 milliseconds and longer), and propose an end-to-end fast retransmission scheme that can reduce these pauses to levels more suitable for human interaction (200 milliseconds). Our work makes clear the need for reliable transport protocols to differentiate between motion-related and congestion-related packet losses, and suggests how to adapt these protocols to perform better in mobile computing environments.
KeywordsPacket Loss Transmission Control Protocol Mobile Host Stationary Host Congestion Window
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- M. Accetta, R. Baron, W. Bolosky, D. Golub, R. Rashid, A. Tevanian, and M. Young. Mach: A new kernel foundation for UNIX development. Proc. of the USENIX 1986 Summer Conference, July 1986.Google Scholar
- B. R. Badrinath, A. Bakre, T. Imielinski, and R. Marantz. Handling mobile clients: A case for indirect interaction. Proc. of IEEE WWOS-IV, October 1993.Google Scholar
- S. Deering and M. Weiser. Private communication. Xerox PARC, October 1993.Google Scholar
- A. DeSimone, M. C. Chuah, and O. C. Yue. Throughput performance of transport-layer protocols over wireless LANs. In Proc. of Globecom’ 93, December 1993.Google Scholar
- D. Duchamp and N. F. Reynolds. Measured performance of a wireless LAN. In Proc. of the 17th IEEE Conf. on Local Computer Networks, September 1992.Google Scholar
- J. Ioannidis and G. Q. Maquire Jr. The design and implementation of a mobile internetworking architecture. Proc. of the USENIX 1993 Winter Conference, January 1993.Google Scholar
- V. Jacobson. Congestion avoidance and control. Proc. of ACM SIGCOMM’ 88, August 1988.Google Scholar
- A. Myles and D. Skellern. Comparison of mobile host protocols for IP. Journal of Internetworking Research and Experience, 4(4), December 1993.Google Scholar
- J. Postel. Transmission Control Protocol. Request for Comments 793, 1981.Google Scholar
- J. H. Saltzer, D. P. Reed, and D. D. Clark. End-to-end arguments in system design. Proc. of the 2nd International Conference on Distributed Computing Systems, April 1981.Google Scholar
- B. Shneiderman. Designing the User Interface. Addison-Wesley, 1987.Google Scholar