Today I bring you a story that has it all: a solar-powered, low-cost, open source cellular network that's revolutionizing coverage in underprivileged and off-grid spots. It uses VoIP yet works with existing cell phones. It has pedigreed founders. Best of all, it is part of the sex, drugs and art collectively known as Burning Man. Where do you want me to begin?
"We make GSM look like a wireless access point. We make it that simple," describes one of the project's three founders, Glenn Edens.
The technology starts with the "they-said-it-couldn't-be-done" open source software, OpenBTS. OpenBTS is built on Linux and distributed via the AGPLv3 licence. When used with a software-defined radio such as the Universal Software Radio Peripheral (USRP), it presents a GSM air interface ("Um") to any standard GSM cell phone, with no modification whatsoever required of the phone. It uses open source Asterisk VoIP software as the PBX to connect calls, though it can be used with other soft switches, too. (More stats in a minute that I promise will blow away your inner network engineer.)
This is the third year its founders have decided to trial-by-fire the system by offering free cell phone service to the 50,000-ish attendees at Burning Man, which begins today in Black Rock City, Nevada. I've posted a few photos of the set-up here. But the project is still new and mostly unheard-of. The second-generation hardware is in beta and the project’s commercial start-up, Range Networks, won't emerge from stealth mode until September (at the DEMO conference).
Two of OpenBTS's three founders are a duo of wireless design gurus that make up Kestrel Signal Processing: David Burgess and Harvind Samra. The third is industry luminary Glenn Edens, the same Edens who founded Grid Systems, maker of the first laptop in the early ‘80s, who is also known as the former director of Sun Microsystem’s Laboratories (among his other credentials). He is Range Networks’ CEO.
Burning Man has become a brutal, but great test vehicle. "There are not too many places you can go where tens of thousands of people show up, all of them with cell phones, in a hostile physical environment – lots of heat and dust, with no power and no mobile service," Edens says.
GSM operates on licensed bandwidth, so for any US installation, the OpenBTS crew always obtains a FCC licence and works with the local carrier to coordinate frequency use. When attendees get into range and power up their phones, the system sends them a text that says “Reply to this message with your phone number and you can send and receive text messages and make voice calls.”
Edens notes: "You can also make phone calls to any number, but you can’t receive them, except from other people at Burning Man. We don’t have a roaming agreement in place with any carriers yet. So calls from people out of range from Burning Man will go to voicemail … but you can check your voicemail." (You can follow the progress of the system setup on Burgess's blog).
Edens jokes that Kestrel gets an equal number of compliments and complaints for making mobile phones accessible at the event. You win some and you lose some.
Certainly, the potential of OpenBTS is a winner. The system is only "as big as a shoebox," Edens says, and requires a mere 50 watts of power "instead of a couple of thousand" so it is easily supported by solar or wind power, or batteries. It performs as well as any other GSM base station which has a maximum range of 35 kilometers and a typical range of 20 kilometers, depending on geography, antennae height, etc.
It can use a wireless backhaul, too. "We’re working with UC Berkeley on a really interesting project on super long distance wireless backhaul. We can also use private microwave and all the usual backhaul technologies," Edens says. A full–power base station with software costs around $10,000. Compare that to the typical $50,000 - $100,000 investment for base station controllers, mobile switching centers and "a whole lot of plumbing" to bring in power, backhaul, etc., in a traditional cellular network.
Like other GSM cell networks, OpenBTS networks can connect to the public switched network and the Internet. Because it converts to VoIP, it "makes every cell phone look like a SIP end point … and every cell phone looks like an IP device. But we don’t touch anything in the phone … any GSM phone will work, from a $15 refurbished cell phone all the way up to iPhones and Androids." Low cost phones are particularly important for projects in impoverished areas, where people can benefit most from better communications services.
"The UN and ITU studies show that when you bring communications services to an area, healthcare goes up, economic well being goes up, education goes up," Edens says, noting that costs and power needs are low enough that even a small village can afford to do this. Users may need to pay $2 or $3 a month.
He brags that setup is downright trivial. "After the Haiti earthquake, we sent a system that was installed at the main hospital in Port Au Prince. They had it working an hour after unpacking it from the box. The hospital PBX was down. They used it as their phone system for about two weeks."
Kestral has sold about 150 units, hardware and software, since last January, with trial systems installed in India, Africa, the South Pacific and a number of other countries. The team has also done a few private installations like oil fields, farms, and ships at sea. They are also providing a system to the Australian Base in Antarctica. Plus OpenBTS has been downloaded about 4,000 times, mostly by researchers able to build their own base stations. It is also of interest for military communications, law enforcement and DARPA projects.
Because OpenBTS relies on licensed bandwidth, the team hasn't been targeting enterprises wanting private campus-wide cell phone networks, though that’s not out of the question. Still, Edens says there's plenty of work to be done for the 60% of the world’s landmass and the 40% of the world’s population that don’t have service, he says, quoting number from the ITU. Carriers such as Telefonica to T-Mobile have expressed interest.
Edens is clearly as proud of the OpenBTS project's technological achievements as he is of its potential role to save the planet. "A lot of people said it couldn’t be done. But software-defined radio technology has gotten so good. It's our second generation radios that we’re testing now and although the three of us have done 98% of the coding work, we've had great support from the open source community."
More power to you.
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