Perpetuu

Abstract

The aftermath of a natural disaster is characterized by lack of a reliable medium for dissemination of information to survivors. The state-of-the-art emergency response systems rely on satellite radio-enabled devices, but survivors, unlike first responders, do not have access to such devices. To mitigate this problem, we present perpetuu, a solar-powered portable GIS microserver. The microserver node can be deployed in a disaster scene and can serve maps to survivors viewable on browsers of off-the-shelf mobile systems. The perpetuu nodes can form a wireless mesh to cover a large geographic region. A key innovation in the design of the perpetuu node is a tiered software and hardware architecture—the system combines a low-power micro-controller with a high-power micro-processor to provide a large spectrum of power states. perpetuu stays in its lowest power state most of the time, and it can in-vitro detect survivors using Wi-Fi sensing, and consequently wake up the higher-power tier to disseminate high-resolution maps on standard web browsers that provide directions to safe locations. The tiered design leverages hardware-assisted energy measurements and a wakeup controller to balance energy harvested from solar panels with energy consumed by the system. We evaluate perpetuu using measurements from our prototype and trace-based simulations, and show that it can function near-perpetually while serving maps to a large number of survivors.