University of Calgary
The butterfly network, the coat of arms of network coding, exemplifies a fascinating fact about networks: a single relayed bit may turn into multiple information bits at different destination. In other words, the same relayed message conveys different information in different side-information contexts. Yet, there are quite many restrictions to have such efficiency in digital network coding. First, the two-for-one gain in the butterfly network example holds in a "Multi-source multicast" scenario, i.e., all destinations decode the message of all sources. Then, there is no noise, and more importantly, there is no interaction between links, for example in the form of interference.