Peer-to-peer, wireless network could help in disasters

LifeNet open-source software would link devices via Wi-Fi, professor says

In the wake of the recent earthquake and during Hurricane Irene, many cell phone users on the East Coast experienced clogged networks that made wireless calling difficult.

Wireless carriers urged users to rely on texting or email to communicate if voice calls didn't work. Home phones using wired networks were also affected by Irene, although many homeowners are removing their wired phones to save money. More than 25% of all homes in the U.S. no longer have a wired home phone, according to the FCC.

Some question whether relying on texts or email during a storm is enough, and they wonder whether new emerging technologies might help. Satellite phones are one option, but they are relatively expensive. Another option is the old-fashioned two-way radio that runs on amateur-radio and public-safety bands.

In the future, one Georgia Tech professor envisions greater reliance on device-to-device communications using typical consumer phones after a disaster. Computer science professor Santosh Vempala has developed LifeNet, which uses free open-source software to allow consumer devices such as laptops, Android phones and battery-powered routers to form ad hoc Wi-Fi, peer-to-peer networks without relying on cellular towers or base stations.

The software is available for download, but Vempala said in an interview that it's still a working prototype. It was demonstrated recently at the SigComm conference in Toronto. The demonstrations provoked interest among representatives of public safety groups that want to have more technologies to choose from when a disaster occurs, he said.

"Even though cell towers are wireless, most of the communications are through a single path, so one person connects through a particular cell tower," Vempala explained. "In a disaster, a lot of people are trying to reach a small number of cell towers and things get congested."

Carriers often use portable cell towers to add capacity during emergencies, but Vempala said "over the long term, a different approach would be better."

Instead of having a cell phone calling along one pathway to a cell tower, LifeNet coordinates multiple paths to other cell phone or laptop users on the same block or area using Wi-Fi. Part of what LifeNet provides is an algorithm to determine if a nearby device has the power and bandwidth to forward data packets to another device, which would then continue to forward the packets until the message reaches the intended recipient, Vempala said.

Since such an ad hoc network would not function on the traditional cellular network, carriers wouldn't be able to charge for the service -- and therefore wouldn't have an incentive to support it. But Vempala said the carriers could arrange to have a kind of "disaster mode" in cell phones that would stay on for a limited time or limited number of relays during an emergency.

While LifeNet is in its early stages, one veteran disaster responder for the American Red Cross said the concept sounds similar to other peer-to-peer technologies already deployed though not widely used.

Keith Robertory, manager of national disaster emergency communications for the American Red Cross in Washington, said he has used robust peer-to-peer wireless systems in recent years that will forward a message through other radios. One that operates on the amateur radio band has a time-out feature built in so that the message does not keep repeating itself indefinitely. The peer-to-peer concept is sound, he said, but hasn't been widely used.

Robertory said LifeNet's success will depend on whether disaster responders find it resilient and easy to use. Still, he said he tends to avoid using untested emerging technologies at the Red Cross in favor of more tried-and-true approaches.

Copyright © 2011 IDG Communications, Inc.

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