Breaking Network Logjams; June 2007; Scientific American Magazine; by Michelle Effros, Ralf Koetter and Muriel M¿dard; 8 Page(s)

The history of modern communications systems has been marked by flashes of startling insight. Claude E. Shannon, mathematician and engineer, launched one such revolution almost 60 years ago by laying the foundation of a new mathematical theory of communications--now known as information theory. Practical outgrowths of his work, which dealt with the compression and reliable transmission of data, can be seen today in the Internet, in landline and wireless telephone systems, and in storage devices, from hard drives to CDs, DVDs and flash memory sticks.

Shannon tackled communications over phone lines dedicated to individual calls. These days, information increasingly travels over shared networks (such as the Internet), in which multiple users simultaneously communicate through the same medium--be it a cable, an optical fiber or, in a wireless system, air. Shared networks can potentially improve the usefulness and efficiency of communications systems, but they also create competition for communal resources. Many people must vie for access to, say, a server offering downloadable songs or to a wireless hot spot.