Communications of the ACM
The Elusive Capacity of Networks
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Credit: University of Houston
Researchers at the Massachusetts Institute of Technology (MIT), the California Institute of Technology, and the University of Technology in Munich have shown that in a wired network, network coding and error-correcting coding can be handled separately without causing a reduction in the network's capacity.
In a network coding system, a node scrambles together the packets it receives and sends the hybrid packets down multiple paths, where they are scrambled again at different nodes. However, each link between nodes could be noisy, so the information in the packets needs to be encoded to correct for errors.
"I could try to remove the noise, but by doing that, I'm in effect making a decision right now that maybe would have been better taken by someone downstream from me who might have had more observations of the same source," says MIT's Muriel Medard.
The researchers analyzed the scenario in which the noise in a given link is unrelated to the signals traveling over other links. They also analyzed the scenario in which the noise on a given link is related to the signals on other links and determined how to calculate the upper and lower bounds on the capacity of a given wireless network.
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