The logistics

The Desa network-in-a-box is a modified Range Networks base station configured to be as hands-off and low-impact as possible. It is a 2G GSM system with two operating channels (GSM absolute radio-frequency channel numbers, or ARFCNs) in the 900MHz range, putting out 10 watts of signal power from an omnidirectional antenna. That gives the system a range of about five kilometers under ideal conditions, but in reality it averages about a three kilometer range because of vegetation and terrain (1.86 miles to 3.10 miles). The whole system is installed in a weatherproof box up a tree and draws less than 80 watts of power. Desa is a four-hour drive from the nearest commercial cell phone coverage.

Getting the radio spectrum needed to run a GSM network in that environment was pretty straightforward—the team just took it. “We’re in the middle of nowhere,” said Heimerl. “Nobody’s going to come for us. Also, we’ve been in discussion with regulators, and they’ve basically said that if no one else is there, it’s OK. We haven’t had anything formal written for that—it’s a gray market. But we feel comfortable. We’re one of undoubtedly hundreds of projects in rural areas in the same position.”

The government’s flexibility on spectrum, however, doesn’t translate into broader cooperation—there was no help from Indonesia’s national telecom as far as integrating the village cell network into the national infrastructure. “Interconnecting in Indonesia is super difficult. It’s not an extraordinarily liberal economic environment for telco, and it’s hard to get people behind you when you're running a 150-person network.” That meant that the Desa network would need another way of reaching the outside world—a critical part of TIER’s mission with the project.

To get that outside connection, the team turned to one of Desa’s few existing pieces of infrastructure: a VSAT satellite dish operated by the school and shared with the rest of the community over Wi-Fi. The VSAT and the Wi-Fi networks—along with the school’s printer/copier and laptops—draw their power from a bank of batteries charged by a 5-kilowatt micro-hydroelectric dam. “We added two batteries and a bigger voltage charger, just for safety,” Heimerl said. The hydropower needs to be shut off every evening for the night to allow the dam’s reservoir to re-fill for the next day, so the batteries are the only persistent source of power. The cell network box draws power from the batteries as well, but only during the day—the network is shut down at night, except in case of emergency, to prevent drawing too much current off the batteries.

While the school used the VSAT connection for educational purposes, the satellite link was largely used by teachers to communicate with their families over Facebook. “Almost all the teachers are from outside the community,” said Heimerl. “They have to contact their parents, need to talk to their sisters, so the way they do that is Facebook. That was the primary use case for VSAT.” The VSAT isn’t enough of a “backhaul” to handle voice communications, and the Desa mobile network isn’t exactly designed for smartphone apps either. But it can handle SMS text messages to and from the outside world. “And that's one of the primary ways people are contacting people outside,” Heimerl said. Since the network’s launch, he said, about 70 percent of its SMS traffic has been to the outside world. That connectivity isn’t just a matter of convenience—it’s helping the village keep the talent it needs to survive. “There’s this doctor who works in Desa, this wonderful dude from Jakarta,” said Heimerl. “And his wife is in Jakarta. To keep a qualified medical guy in this community, you have to have the connectivity so he can keep in touch.”

That connectivity comes with a strange Internet twist. Without a tie to Indonesia’s telephone network, TIER turned to Nexmo, a cloud SMS provider based a few blocks from Range Networks in San Francisco. Each of the phones added to the Desa network has a valid phone number to communicate with the outside world. The TIER team coded an interface into Nexmo’s cloud API for their network-in-a-box that automatically provisions new numbers when new SIM cards for the network are purchased and brought online.

Cellular bitcoins and Chatroulette

In order for the network to be self-sustaining, it had to have a way for TIER’s partner—the school—to bring in money to pay for upkeep and the satellite usage. TIER and the school also wanted to integrate the network into the local economy and allow merchants to resell the service. “We were creating an ecosystem of telecom that supports 150 people in the middle of nowhere,” Heimerl said. That meant adding a billing system plus a way to allow local merchants to sell phones and credits to customers without much (if any) infrastructure and minimal training. All of the support required needed to be built directly into the network.

A teacher at the school supports the network by selling SIM cards to a group of local merchants—each of whom sells phones and has electricity to charge phones as well. These merchants resell the SIM cards and sell usage credits that they also buy wholesale from the school. “Once you have a SIM card, send an SMS to 101, and it will automatically give you a phone number on our network,” said Heimerl. “The system will buy the number from our provider, put it into our system, and send it to the user. Then they get a text message telling them what their phone number is.

TIER had to build the usage credit system for the network as well. Resellers buy usage credits from the school, and the credits can be added to accounts via an SMS message from the resellers. But the credit system isn’t limited to just buying and counting usage. Early on, the team made the decision to eventually allow customers to trade credits with each other—turning the prepaid credits into a sort of digital currency. “We built this little system where someone who has credit sends an SMS to a certain number with a code,” said Heimerl. “If there's a phone with that code, money gets transferred to that phone.”

Last June, the team turned the system on and sent out a broadcast text message announcing that the credit transfer service was available. Heimerl said there are still a number of questions about how far the digital currency part of the service will go. “We're not sure if this is going to be a good idea or not, but we're researchers, so we try things. There was a bug at one point where someone could transfer themselves money and they would get extra. It's stuff like that we worry about—this is real money and real people we’re dealing with. And they can’t lose $10—it's a big deal. There’s also the question of whether we let people cash out. So we need to be safe about it, and we're trying to see if there's a smarter way to do this.”

As a result of the prepaid credit system, the Desa cell network is doing better than just breaking even—it’s bringing in a profit. “The numbers are great,” Heimerl said. “Our revenue per user is about double that of the national carrier. There are local people making a lot of money as a result, and most of the money is staying in the local community, really benefitting a lot of people in foundational ways.”

The digital currency application isn’t the only thing on the TIER team’s research agenda. While the core mission is well under way, there are other experiments Heimerl wants to try. “The racial politics in Desa are complex,” he said. “There are really two communities—some speak the local language and some speak Indonesian—and we’re trying to find ways to bridge the communities.”

One approach that the team is considering deploying is a service called “Find a Friend.” It’s the mobile phone version of Chatroulette—phone users can dial in and register their number, and the system will connect them to someone they haven’t talked to before. “If you talk to someone for a particular amount of time, it gives you a credit,” Heimerl explained. For now, there are a few details of Find a Friend that need to be ironed out, such as dealing with calls between men and women that might violate local social norms.

Your own private Verizon

It doesn’t take much imagination to see how what TIER has done in Papua could easily be applied in rural areas around the world—including underserved areas in the US, where cellular coverage of any kind could be a boost to public safety as well as the economy. With the addition of white space mobile as an option, the door could be opened to a number of different applications: emergency response or private communications for mining operations and other industries that need mobile networks.

But most of the demand for the technology right now is in the developing world for a number of reasons. “Many African countries are leading in white space adoption,” Kozel said. “Also, in emerging regions, mobile is more of an overt political issue than it is here. We’re working with an operator in a Latin American country who has been told by the government to extend service to rural areas and is looking at doing it in a less expensive way.” Range Networks has not yet “even tried to talk to the incumbents” in the US about fitting into their rural coverage plans, Kozel said, because there’s a lot of work that remains to be done to make the product compatible with their systems. “We need to have a more mature product in some ways. We have to show that it can scale—currently, the system can handle 30 concurrent calls. And we need to do more work to fit into billing solutions.”

Instead, the company is focusing on the white space realm for its next big push, as well as tapping into emergency services and other applications that need just one or two base stations (like labs and universities). Range is also looking for ways to push OpenBTS into other mobile networking applications that have little to do with phone calls—applications where the system is used as the basis for mobile area networks that connect devices and applications.

“When you think of GSM, one of the key characteristics is communications,” Kozel said. “But it also authenticates itself. And the connection moves with you.” Using software-defined radios, those parts of GSM could be applied in ways “that won’t have anything to do with GSM networks as we know of them,” he said. “White space is a simple app, and a compelling one, but it’s just one—there’s search and rescue, triangulating on where a handset is without GPS, and there are other applications you can build on top of that sort of platform.”

Whether Range and other companies can succeed at creating a real open mobile market that handles the types of applications Kozel has in mind—such as machine-to-machine communications, autonomous systems, and long-range unlicensed spectrum networking applications of every other shape and size—remains a very big question mark. The capability is similar in many ways to what the military set out to do with the Joint Tactical Radio System over a decade ago. They spent billions trying to pull it off. But considering what a few programmers and engineers have been able to do with about $10,000 worth of Range’s gear in the Papuan jungle, maybe telcos—and the Department of Defense—should be paying attention.