Muriel Médard, “Network coding - where to now?”, May 18th, 2006

Network coding has emerged as an effective way to improve the operation of networks by allowing algebraic mixing of data in the interior of networks. This technique allows for full use of available degrees of freedom and energy. Such mixing leads not only to gains in capacity with respect to traditional point-to-point routed networks, but also allows in multicast settings to have a distributed operation of the network.
These advantages of network coding render it particularly attractive for wireless settings, in which degrees of freedom are often automatically overheard by nodes which were not intended recipients.

We outline distributed operation and optimization of multicast networks in wireline and wireless settings with losses and mobility. We show that distributed optimization, akin to that found in point-to-point traditional routing, can be effectively decoupled from coding considerations and can yield significant improvements in terms of energy use in wireless networks. Moreover, even in settings where theoretical results are scant, network coding lends itself well to heuristics that can outperform traditional routing approaches. Using both theoretical results and detailed emulations of heuristic approaches, we present some examples of practical network coding for wireline multicast, wireless communications and file downloading.

We conclude with some questions about possible implications of the use of network coding for protocols, security and network design.


Muriel Médard is a Harold E. and Esther Edgerton Associate Professor in the Electrical Engineering and Computer Science at MIT and the Associate Director of the Laboratory for Information and Decision Systems. She was previously an Assistant Professor in the Electrical and Computer Engineering Department and a member of the Coordinated Science Laboratory at the University of Illinois Urbana-Champaign. From 1995 to 1998, she was a Staff Member at MIT Lincoln Laboratory in the Optical Communications and the Advanced Networking Groups. Professor Médard received B.S. degrees in EECS and in Mathematics in 1989, a B.S. degree in Humanities in 1990, a M.S. degree in EE 1991, and a Sc D. degree in EE in 1995, all from the Massachusetts Institute of Technology (MIT), Cambridge. She serves as an Associate Editor for the Optical Communications and Networking Series of the IEEE Journal on Selected Areas in Communications, as an Associate Editor in Communications for the IEEE Transactions on Information Theory and as a Guest Editor for the Joint special issue of the IEEE Transactions on Information Theory and the IEEE/ACM Transactions on Networking on Networking and Information Theory. She has served as a Guest Editor for the IEEE Journal of Lightwave Technology and as an Associate Editor for the OSA Journal of Optical Networking.

Médard's research interests are in the areas of network coding and reliable communications, particularly for optical and wireless networks. She was awarded the IEEE Leon K. Kirchmayer Prize Paper Award 2002 for her paper, The Effect Upon Channel Capacity in Wireless Communications of Perfect and Imperfect Knowledge of the Channel," IEEE Transactions on Information Theory, Volume 46 Issue 3, May 2000, Pages: 935-946. She was co- awarded the Best Paper Award for G. Weichenberg, V. Chan, M. Médard, "Reliable Architectures for Networks Under Stress", Fourth International Workshop on the Design of Reliable Communication Networks (DRCN 2003), October 2003, Banff, Alberta, Canada. She received a NSF Career Award in 2001 and was co-winner 2004 Harold E. Edgerton Faculty Achievement Award, established in 1982 to honor junior faculty members "for distinction in research, teaching and service to the MIT community."  Médard is also an Associate House Master Simmons Hall.