Continuing our series of articles about innovative technologies to access the last mile, I would like to introduce the Free Space Optics (FSO).
FSO is a line-of-sight technology that enables up to 10 Gbps of data, voice and video communications through the air, allowing optical connectivity without deploying fibre-optic cable or securing spectrum licences.
The light is focused by using either light emitting diodes (LEDs), or lasers (light amplification by stimulated emission of radiation). The use of lasers is a simple concept similar to optical transmissions using fibre optic cables; the only difference is the medium. Interestingly enough light travels faster through air than it does through glass, so it would be fair to classify FSO communications as optical communications at the speed of light.
This idea is not new; it has roots going back over 30 years to the era before fibre-optic cable became the preferred transport medium for high-speed communication. It was originally used by the military and space aviation pioneers for secure communications.
These free-space systems require less than a fifth the capital outlay of comparable ground-based fibre-optic technologies. Moreover, they can be installed in a matter of days. The result is that a service provider can be generating revenue while a fibre-based competitor is still seeking municipal approval to dig up a street to lay its cable.
In the United States, an estimated 95% of buildings are within 1.5 km of fibre-optic infrastructure, but at present, are unable to access it. Connecting them with fibre can cost $100,000-$200,000 km in metropolitan areas, with 85% of the total tied to trenching and installation. Furthermore, increasingly in some cities (i.e. Washington D.C.) trenching is limited due to the obvious effects on traffic, pollution and disruption for citizens.
Until recently, the technology was used primarily for enterprise connectivity. It shows up mainly in local-area networks spanning multiple buildings, where right-of-way was an obstacle to leasing copper lines or fibre-optic cabling. Over the past few years, FSO has started to move into more mainstream service.
This technology has been quickly dismissed in the past because of its unreliability under poor weather conditions. The telecommunications industry works on the basis of the “famous” 5 nines of reliability 99.999%. For example: fog, rain and the occasional bird have created serious problems for those based outside Southern California. Nevertheless, important steps have recently been made to obtain the required reliability. In particular LightPointe (one of the leaders in FSO) has developed a hybrid solution that combines FSO with a microwave radio back up. When the FSO stops working because of the heavy fog, the back up kicks in and restores the connections. This solution together with the use of active-alignment systems to limit the effects of urban building swaying and a better understanding of the dynamics of a network in different weather conditions (in non desert conditions the distance of the link should be limited to under 500 m) has contributed to the rapid acceptability of such systems.
For the point of view of safety some critics point out that having a laser beaming in a city could be damaging to the health and may possibly disturb people’s activities. The safety issues of lasers are being strongly addressed by the key players; most of the companies now meet the strict standards of the Food and Drug Administration (FDA) and the guidelines International Electrotechnical Commission (IEC).
It is quite obvious that the potential of this technology is enormous in countries like Latin America, India or China where the poor infrastructure demands an innovative approach to capital expenditure. Nevertheless, I believe that even in “old” economies, like Europe and the US, this technology will gain the necessary respect in combination with the more established ones. Telecom companies may finally effectively deliver broadband at a fraction of the cost and time.
Please find attached a recent article on the subject from the Red Herring. In next issue of the Ariadne Capital Journal we will present an interview with Christian Rook, Managing Director of LightPointe Europe GmbH.

http://www.redherring.com/insider/2002/0308/2033.html