MobileActive.org recently had the opportunity to test an off-the-grid GSM base station. Kurtis Heimerl presented The Village Base Station (VBTS), (link is a PDF) a low-power means of providing mobile network service without grid power or network infrastructure.
Below, Heimerl demonstrates the basic workings of a GSM networks and OpenBTS, an open-source platform that allows one to set up a cellular network at a fraction of the cost of a GSM network. Heimerl shows how phones find their base towers and settle on a frequency, and how OpenBTS condenses that process into a lower-powered, cheaper network.
The Village Base Station is built around voice and low-bandwidth data transmissions. It is an economical solution for rural residents who are outside of typical network coverage or power access, or for people living in situations where network outages occur. In a white paper presenting the VBTS, Heimerl and co-author Eric Brewer describe the project as, "essentially an outdoor PC with a software-defined radio that implements a low-power low-capacity GSM base station. Long-distance WiFi provides 'backhaul' into the carrier." Below are images of elements of the Village Base Station and screenshots from our 'hackday' in a large American city when we demo'ed VBTS with Heimerl. (Warning: If you try this at home, be aware of your local regulator's potential licensing and other restrictions for setting up such network/connecting to it)
