Open-source app lets responders mesh from smart phones, laptops

One of the many challenges facing first responders in the wake of natural disasters is that local or regional communications networks are either out of commission or overwhelmed. Researchers at the Georgia Institute of Technology’s College of Computing have developed a wireless system that allows emergency personnel to communicate in areas where the local infrastructure is inoperable.

LifeNet is a mobile ad hoc network (MANET) designed to link smart phones and other handheld devices in the field from a single device — a computer connected to the Internet or a satellite phone.

The free, open-source software, available for download here, allows several users in an area without satellite phones, but with smart phones or Wi-Fi-enabled laptops, to connect to the LifeNet network.

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The system is designed to overcome the challenges found in traditional radio networks, where the entire network can fail if several nodes are disabled or cannot link to each other. This is particularly a challenge for wireless networks in areas without infrastructure, because wireless links are very transient, said Santosh Vempala, a distinguished professor of computer science at Georgia Tech's College of Computing and LifeNet project lead.

Although MANET-based systems work very well in situations where there is little or no infrastructure, there is very little information available on managing and running large ad hoc networks, Vempala said. Ideally, in a multinode network, all of the devices would be able to listen to each other and allow messages to reach their destinations via multiple paths between connected devices, he said. But there was no available algorithm available to do this.

At the heart of LifeNet is an algorithm that instructs a handheld or wireless device when to retransmit a signal. The open-source software developed by Vempala and graduate student Hrushikesh Mehendale allows LifeNet to establish device-agnostic, multinode networks and to vary communications depending on available bandwidth.

As more nodes and bandwidth become available, the system can scale up the types of messages it can handle, from voice to data. However, a key element of the system is its ability to provide reliable, basic low-bandwidth communications.

“As long as there is some connectivity, you will be able to send text messages,” Vempala said.

LifeNet networks start up when the first node is in place. Each LifeNet-enabled computer is both a client and a router capable of moving data to and from other local wireless devices. The network also remains intact when the nodes are moved to different locations.

The software is now undergoing field tests with disaster management agencies in the United States and India. The next step for the effort will be to collect feedback and refine and develop a product for release sometime early next year, Vempala said.



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