Ad-hoc messaging infrastructure for P2P communication in disaster management

Traditional means of communication rely on a centralized service provider, which may not be functional in the wake of a disaster. With a traditional cellular service provider, when somebody (Alice) wants to send a text message to someone else (Bob), the message is sent from Alice's phone to a cellular network and then finally to Bob. This process happens regardless if they are located on opposite sides of the world or are in the same room. In this paper, we present the design and implementation of a peer-to-peer (P2P) network which will route text messages along the shortest reliable path. By “shortest path” we mean that if Alice and Bob's phones are in wireless range of each other, the message passes only through their phones over the wireless link. If Alice and Bob are located further apart and their wireless radios are out of range, then a repeater node which can be reached by both Alice and Bob can be deployed and the message will pass through this node, again taking the shortest path. The network can be deployed with inexpensive off-the-shelf microcomputers, such as the Raspberry Pi, which can run off batteries in the event of a power outage. These nodes can be easily deployed and need not be trusted as the messages are encrypted and signed. During our tests, we were able to send text messages across a building over our mesh-network composed of five Raspberry Pi microcomputers running our software and using ad-hoc Wi-Fi for neighbour-to-neighbour links.