The £25 Raspberry Pi becomes a GSM base station
Engineers from PA Consulting Group have managed to create a GSM base station based on the tiny Linux-powered computer Raspberry Pi and some open source software, running their own mobile phone network in a sealed room.
Operating a mobile network usually requires an expensive GSM base station and other infrastructure, but Cambridge-based PA conducted this experiment to highlight the hidden value of cheap, off-the-shelf solutions, keeping the system tucked indoors to avoid encroaching on licensed spectrum belonging to mobile operators.
The Raspberry Pi, created by the non-profit Raspberry Pi Foundation, is a basic computer that can be connected to a TV or monitor via HDMI. It can be used for many of the things that your desktop PC does, including office work, Internet browsing and high-definition video playback – all possible through a circuit board the size of a credit card, which costs around £25.
The device was designed primarily to get children interested in programming, and inspire a new generation of British innovators.
In almost a year since its release, Raspberry Pi has been used for a variety of exotic projects. We have seen supercomputers housed in racks made of Lego, microservers for accounting software, conversions of old hardware into laptops. The clever device was shown to be running not just specific Linux distributions, but HTML5-based Firefox OS and Google’s Android too.
Now, it turns out the tiny computer can also successfully route voice and SMS traffic through a GSM network. PA hooked up the Raspberry Pi to a radio interface and,
using two pieces of open source software (OpenBTS and FreeSWITCH), made it perform the same functions as a 30-foot cellphone tower.
The wireless experts had to tweak the software by hand, as well as code-optimise the signal processing. Once this was done, the new network was capable of connecting mobile phones at PA labs. The consultancy tested the device in a special facility, to ensure no laws on frequency spectrum were broken.
“This proves what can be achieved through low-cost off the shelf-systems. Just imagine the other possibilities that other such low cost technologies could inspire across other sectors and industries,” commented Frazer Bennett, a technology expert at PA.
You can see a short video explaining how the consultancy created its private network below: