Let’s say you are hiking the Adirondack Mountains in New York or the Rocky Mountains in Colorado. It is getting dark, you are miles from camp, and you sprain an ankle. You have no cell service. What do you do?

Or maybe you are dancing at a music festival with friends — say, Bonnaroo in Tennessee or Burning Man in Nevada. Among those hordes of people, it doesn’t take long to get separated from your group. But, because nearby cell towers are overwhelmed, there is no one you can call. What do you do?  

Or perhaps you are riding out a hurricane in a coastal city. Water is flooding through your house, a tree has fallen on your car and — you guessed it — cell towers are down. What do you do? 

Even in the United States, where connectivity is considered relatively decent, great swaths of the country still have spotty service  … or none at all. Off-the-grid communication — which does not require pre-existing infrastructure such as the internet, cellular towers, Wi-Fi hotspots, or even satellites — can be a crucial and even lifesaving commodity. But, despite a wide-range of potential applications, it has never been mainstream. 

Now, thanks partially to research involving scientists at the University of Delaware — an institution with a long history of innovative research on off-the-grid networks — that might be changing. 

One of these scientists is Ayush Dusia, who earned a doctorate in computer science in December of 2019. His dissertation focused on the Mobile Ad hoc Network, or MANET. In such a system, there are no cell towers or satellites or internet routers. Instead, handheld devices relay messages directly to one another. They do so in a “multi-hop” manner, meaning when two devices aren’t within range, others in between relay — or hop — a signal from one to another until the message reaches its final destination.

There are challenges.

“The mobile devices in the network may move around and change the wireless connectivity,” Dusia said. Signals sometimes get dropped. Additionally, if the network is low-bandwidth, meaning it can’t handle too much data at once — say, the kind of network that operates on the same radio frequencies as a walkie talkie — it can easily be overwhelmed if too many signals are sent at once. This results in lost or dropped messages that need to be retransmitted, causing quicker battery drain.