You Can Create Your Own Cell Network with a Raspberry Pi and SDR

It’s probably safe to say that most people, in the United States at least, aren’t happy with their cell service. High prices, slow data connections, and spotty service are all to blame. There is, of course, a good reason for this: the United States is a massive country, full of wide open spaces. Once you get away from the coasts and major cities, the population density of cattle is usually higher than humans.

If you’re away from the safety of civilization, it might be nice to still maintain cell service. Matthew May and Brendan Harlow, students at Vermont’s Champlain College, were able to build their own cell network that works independently of a carrier. The gist of the setup is that a Raspberry Pi is connected to an SDR (software-defined radio) device, which creates a signal that a cell phone can connect to.

As you might expect, not just any SDR device will do the job here. It needs to be able to broadcast on the correct frequencies, and handle the proper communications protocols. For their build, Matthew and Brendan used a bladeRF x40; it’s pricey at $420, but got the job done. The project also required programmable SIM cards, which can be tricky to work with.

The question on most readers’ minds now will be “so, how does it connect to the rest of the world?” The answer is that it doesn’t—unless the Raspberry Pi itself has an internet connection. But, that’s doesn’t mean it’s not useful. While their prototype only has a range of 60–100 feet, that can be amplified. This might make it useful in remote locations, or in urban environments when traditional cell service has been lost (like during a natural disaster). Details are available on the project’s GitHub page.