When MTN - the leading mobile operator in sub-Saharan Africa - arrived in 1998, however, the country had barely begun to reemerge from the horrors of civil war and the ensuing near-collapse of the communications infrastructure.

Per Eriksson, CEO at MTN RwandaCell, recalls: "There were only 20,000 fixed lines in a country of 8 million people. Today, we have more than 300,000 mobile customers and the market has grown by an annual 30-40 percent over the past three years. This year alone, we expect to grow by 100 percent."

Eriksson confirms that mobile communications have made a huge difference to the country. "Without telecommunications, there is little chance of attracting foreign investment and economic development is severely hampered."

Landlocked Rwanda is the most densely populated country in Africa, with few natural resources and almost no industrial base. Looking elsewhere for economic growth, Rwanda's government plans instead to turn the country into a knowledge-based economy and a regional IT and communications hub.

Known as the Land of a Thousand Hills, Rwanda offered MTN a tricky task in establishing a mobile network that today reaches 90 percent of the population and 80 percent of the surface area. As sole supplier, Ericsson has delivered a complete GSM system with base stations, switching equipment and charging solutions.

Thomas Sonesson, country manager at Ericsson Rwanda, says: "These markets require network solutions that minimize the operators' total cost of ownership, in order to allow them to profitably provide affordable services to new subscribers who may initially spend as little as USD 5 a month. This presents operators with the task of building networks that are both cost-effective and scalable, yet offer the quality required by tomorrow's demanding applications."

Many of the continent's new growth markets are found in areas where tomorrow's mobile users are scattered throughout vast areas, which renders cost-efficient network expansion particularly important in view of the initially low spending among these users. Sonesson explains that many of these markets have benefited from Ericsson's Coverage Expansion solution, a package of enhanced radio network components that provides extended coverage with a minimum of base stations.

"New growth markets pose new challenges in building cost-effective and scalable networks. The Ericsson Coverage Expansion solution has been developed to meet these needs through advanced functionality that minimizes the number of sites required."

A key element of this package is the double transceiver unit (dTRU), a self-contained unit consisting of two transceivers on one board. To improve the downlink, the output power of the two individual TRUs is combined with the help of a unique software solution called transmitter coherent combining (TCC). This lets an operator either reach twice as far as when using a single TRU or concentrate radio capacity to densely populated cell areas.

Just as important as the downlink - but often neglected - is the uplink performance of the radio network. The Coverage Expansion solution includes advanced radio-network functions such as four-way diversity, which help signals get picked up at greater distances from the base station.