Network Coding—The Magic of Mixing [Point of View]

The Internet delivers information by having routers store and forward packets, in a way similar to how the postal system delivers mail. Such a forwarding model has been deeply entrenched in our minds. There seemed hardly any doubt about it. Around the year 2000, a group of information theorists - Rudolph Ahlswede, Ning Cai, Shuo-Yen Robert Li, and Raymond W. Yeung - challenged this model. An intermediate node in a network receives some packets and sends out some packets. Fundamentally, the node can output any functions of the received packets, not necessarily copies of the received packets. Ahlswede et ah demonstrated that it is possible to do better than forwarding, by mixing information (e.g., outputting a packet that is the xor of two received packets). This is now called network coding. This groundbreaking work ignites an enormous amount of enthusiasm. It is time to revolutionize network communications!