September 27 brought a small but significant milestone for the rural network access needed to connect a significant proportion of the 2 billion people without affordable mobile coverage. The people of Santa Maria Yaviche made the first calls from their tiny, remote village deep in Mexico's northern Oaxaca mountains, a five-hour drive from Oaxaca City.
The milestone followed advances in open-source RF technologies and considerable work by the Rhizomatica project. For the past two years, Rhizomatica has been working with Mexican communities and the Mexican government to obtain concessions (ordinarily costing operators several hundred million dollars) so approximately 5,000 small, indigenous communities could build their own local mobile networks in the Oaxaca, Veracruz, Puebla, Guerrero, and Tlaxcala states of Mexico. The project cost just a few thousand dollars thanks to open-source technologies and low-cost construction materials.
Santa Maria Yaviche is a five-hour drive from the nearest city.
A base station with a built-in PBX ensures no external infrastructure is needed to connect calls. It lets villagers make free calls to one another even if the unstable satellite Internet connection goes down. The service lets villagers call one another after an accident. It also enables the village doctor to make phone calls, rather than walking the whole day to check in on patients.
The network in Yaviche runs with the UmDESK open-source base station, which is built on top of the open-source hardware platform UmTRX. It allows up to 14 concurrent voice connections. When this capacity is exhausted, the system switches settings to nearly double its capacity, making a tradeoff in voice quality.
The UmDESK open-source base station with two 2W boosters.
A flexible RF platform is essential for the service to run effectively and to negate interference from competing networks that may be built in the future. So the base station uses field-programmable RF transceivers, allowing the network to be calibrated across a wide range of frequencies from 0.3 GHz to 3.8 GHz.
The base station is positioned in a corner of the village with two patch antennas used to direct radio transmission to the village center. These are hooked to a six-meter bamboo pole placed on a two-story building, giving coverage across the entire village, even inside the thick-walled buildings found in the region.
Software reliability is also vital. For this, the system runs a variant of the Osmocom open-source software.
Six-meter bamboo masts cut costs by serving as poles.
Surprisingly, in a village of just 700 people with no mobile coverage, the network immediately detected more than 100 active phones. The phones were used as calculators, alarm clocks, game machines, and more. Two weeks after installation, the Yaviche mobile network had more than 400 phones registered. In a typical day, it connects 500-1,000 local calls and delivers 3,000-4,000 SMS messages.
"We finally have a low-cost, stable solution that meets the demands of rural deployments and is in line with local budgets," said Rhizomatica's head, Peter Bloom.
The next step for the village is to get a stable Internet connection to be able to link to surrounding villages. Among other uses, the village doctor wants to connect with the nearby community, Talea de Castro, to access its clinic and lab for quicker diagnoses.
The first calls are made.
The Rhizomatica project's work in Mexico is based on United Nations and International Labour Organization conventions. Thus it can be replicated elsewhere.
-- Alexander Chemeris, CEO, Fairwaves, and Ebrahim Bushehri, CEO, Lime Microsystems