Researchers are creating mobile networks that can sustain communications even in the face of broken links and long delays.
The quest for such disruption-tolerant networks, or DTNs, is being driven by military, scientific and emergency-response wireless networks, which typically lack the connectivity, stability and predictability of conventional wired networks. Instead, researchers say, the hallmarks of a DTN are the very problems that quickly bring a conventional wireless network to its knees: frequent and unpredictable disconnects, changing nearby nodes and very long delays. The trade-off: it takes a lot longer to send and receive data over a DTN.
You can think of it as the “it’s better than nothing” approach to networking.
Breaking through breakdowns
Researchers at BBN Technologies, of Cambridge, Mass., have begun the second phase of a DTN project, funded by $8.7 million from the Department of Defense’s Defense Advanced Research Projects Agency (DARPA). Earlier this year, the researchers simulated a 20-node DTN. With each link available just 20% of the time, the network was able to deliver 100% of the packets transmitted.
“Using traditional [network] routing in the same scenario, and depending on the nature of the outages, there would be a very, very low percentage delivered, or none delivered,” says Stephen Polit, project manager for BBN’s DTN research, dubbed SPINDLE.
