Free-space network is biggest ever

17 Jun 2002

Roof-top lasers beam information across South Africa in the largest ever gigabit free-space optical network.

UK company Cablefree claims it has installed the largest ever gigabit free-space optical (FSO) communications network.

Built for a defense industry client in South Africa, the network is now fully operational and is used by around 2 500 users in 19 separate buildings.

The network uses FSO links to transmit full-duplex voice and data between buildings via low-cost semiconductor lasers on roof-tops. The lasers operate at 785 nm and 980 nm and, across uninterrupted free space, can transmit data between 200 m and 4 km at rates from 2 Mbit/s to 2700 Mbit/s. Unlike radio-based systems, FSO communications links require no licensing, planning permission or excavation work for operation and take less than three hours to install.

Marius Dippenaar, CEO of Cablefree South Aftrica said: "We have just deployed the largest ever gigabit laser network across a five square kilometre campus. There are no radio-frequency links across the site for security reasons, which is why our laser system has been selected for its inherently secure mode of data transmission."

Previously, the defense client relied on limited fibre infrastructure, and older copper cabling, but according to Dippenaar, these networking connectivity solutions did not provide the required performance or reliability. "We have now been able to integrate what was previously a series of separate local area networks into one campus-area laser network solution," he added.

The Cape Peninsula region, where the client is located, is prone to regular sea-mist but Cablefree claims that its system can cope with these weather conditions and has excellent atmospheric penetration