A Tiny Cell-Phone Transmitter Takes Root in Rural Africa

Worldwide, at least a billion people don’t have access to cellular communications because they lack electricity to run traditional transmitters and receivers. A new low-power cellular base station being rolled out in Zambia could bring connectivity to some of those people.

Weighing just five kilograms and consuming just 50 watts, the gadget provides connectivity to 1,000 people and is “the lowest-power consumption outdoor base station in the world,” says Vanu Bose, CEO of Vanu, the Cambridge, Massachusetts-based company that built it.

One destination for the pint-size base station is Chaimiaka, a village 115 kilometers from the Zambian capital, Lusaka. The units require a second piece of equipment, known as the backhaul, to handle the connection to the main network. In Chaimiaka, this is done with a microwave transmitter that consumes 25 watts; it links village communications with a traditional base station 17 kilometers away.

In other settings, a satellite connection or fiber backhaul may be used. Powering the base stations and backhaul connections can be done with photovoltaics, batteries, generators, or whatever grid connection may be available.

Zambia’s existing network coverage illustrates the global problem. Of the central African nation’s 13 million residents, 8.5 million live in rural areas and have spotty or absent coverage, which is visible on this map. In the developing world, networks are typically built out in urban areas and along main highways, but that leaves a lot of people without access. 

To achieve the low-power consumption, the company’s main strategy was to use a single software-controlled processer to handle all processing and networking tasks. On typical base stations, these jobs are done by two or three processors. “At every step of the design, we ask ‘How can we do this differently to reduce power consumption?’ resulting in changes to many aspects of a traditional base station design, including antenna usage, filtering, and signal processing,” Bose said.

In the future, this and other base stations could be made even more efficient with coming advances in super-efficient amplifiers—the gadgets that change electrical signals into radio waves. These gadgets are, by far, the largest users of electricity in all base stations (see “Efficiency Breakthrough Promises Smartphones That Use Half the Power”).

The technology is being rolled out with a Zambian partner, Connect Africa. In a company blog describing a meeting with a traditional leader, Chief Shakumbila, the chief initially expressed some reservations about the influx of technology, but added: “We can use technology to preserve culture. We will coexist—there is no way we can stop it because we have to keep up with the world.”

Technology is indeed pressing ahead on the African continent, centered in major hubs, including Nairobi. Electricity supplies are a key limiting factor. “As Africans have more disposable income, and also are getting used to the influx of Internet and mobile connectivity, the need for power increases,” says  Erik Hersman, director of iHub, a Kenyan startup incubator (see “Kenya’s Startup Boom”). “The western understanding of energy infrastructure doesn’t fit the continent either; it needs a rethink. And that’s why I think some of the biggest gains will be made in the coming years across Africa—there’s just too much of a growing demand and too few solutions that fit.”

Among the other solutions emerging is a gadget called the BRCK, a device that can connect with any network in the world, provide eight hours of wireless connectivity battery life, and can be programmed for new applications, such as remote sensing (see “This Box Keeps Information Flowing During a Crisis”).