An Open-Source, Solar-Powered, Portable Mobile Network

A team of technologists have developed a portable, low-cost cellular network alternative, perfect for providing coverage to poorer, rural, and hard-to-reach areas where few established network providers dare go.

The OpenBTS project (BTS = Base Transceiver Station, and brace yourselves for several more acronyms coming up) allows users to construct an open-source, software-based network that can be installed and operated at one-tenth the cost of current technologies. This means that companies operating a BTS network could potentially turn a profit charging users only $2/month.

The (rather intimidating) technical details behind the OpenBTS project are described at length on their blog, but thankfully this review by Engineering For Change helps simplify the process:

At its core is open-source software that creates an interface for cellphones to connect to the network. The software is installed on a computer with a Linux operating system. An open-source device, called a Universal Software Radio Peripheral (USRP), plugs into the computer. Together, they create a signal that looks just like any signal for GSM phones... To complete the trick, the software plus the USRP hardware links to an open-source PBX called Asterisk. The PBX, a private bank exchange, is a server that acts like a switchboard to place calls.

As well as providing an alternative to conventional cellular networks, the OpenBTS network is highly portable, making it easy to bring connectivity to the most remote locations. OpenBTS’ rapid deployment kit is a transportable version of the technology which essentially amounts to  a mobile network in a box. As the project’s website explains, “Each box is a self-contained BTS unit, runs on a 12-16 VCD supply, [and] has a service radius of about 10 miles in rural conditions... Robust, simple, inexpensive.”

Once the equipment is set up, the network will show up on the screen of any GSM mobile phone within range of the transceiver (GSM is the most widely adopted cellphone standard in the world). If the laptop is connected to the Internet, the network expands to the broader communications network through VoIP (Voice Over IP).

Because of its portability and GSM compatibility, the BTS network could revolutionize mobile phone usage in rural or distant areas deemed too inaccessible by conventional carriers. And it’s got a huge financial edge, as well. The entire network, including building an optional base antenna to widen the network (shown at left), costs roughly $20,000, compared to the $200,000 a conventional phone company would need to invest in an off-the-grid network. And since it’s powered by solar panels, OpenBTS saves thousands of dollars in transporting, operating, and guarding diesel, according to co-founder David Burgess.

Through years of development, the network has been field-tested a number of times. Burgess and his team tested OpenBTS in Nevada’s Black Rock Desert at Burning Man (an area with very little coverage), and also at the entirely un-networked Polynesian island of Niue. Most notably, the BTS system was picked up by Orange and Ericsson, who in 2009 announced plans to install 100 base stations in rural Africa.

Despite its successes in the field, OpenBTS faces a few very real obstacles -- fixing software bugs, meeting network regulations and standards, addressing security and encryption issues, and ensuring a reliable signal, to name a few (at Burning Man 2008, voice communications clogged the network and forced the team to transmit only SMS messages). Fortunately, the entire set-up runs on open-source software and hardware, meaning that entrepreneurs and technicians around the world can work together to build a stronger BTS network.

As astonishing numbers regarding global mobile subscriptions and handset sales continue to grow, it’s important to remember that the devices themselves are only as powerful as the network in which they operate. OpenBTS provides this gateway to connectivity in the rural areas which need it most -- hard-to-reach places where BTS-enabled mobile communication could improve health, education, finances, and citizenship.