SkyFiber revives optical wireless

Free space optics never amounted to much in the telecom industry, flashing briefly in the portfolio of Terabeam Wireless before falling to the wayside like so many other broadband wireless technologies in the last decade. But a company called SkyFiber is trying to revive the technology with the belief that demands for high-capacity mobile backhaul have created a prime opportunity for optical wireless links.

As the name implies, free space optics uses light to transmit data, much the same way as fiber optics systems but through the air, not over a fiber line. Founded in 1996, SkyFiber is hardly a new company, but for most of its existence it’s been flying under the radar, researching optical technologies and accruing patents. According to CEO David Achim, its success in patenting much of free space optics intellectual property is what forced Terabeam to ultimately get out of the business. Last year, SkyFiber decided that its technology and its market were ready for commercial deployments. It raised $32 million in venture funding and began trialing its equipment with local governments and wireless operators and is now set to start selling its SkyLink product commercially.

“Free space optics was an overhyped, overpromised and under-delivered technology that left a bad taste in people’s mouths’,” Achim said, explaining why the technology fell off the radar after Terabeam’s initial trials. But SkyFiber has managed to optimize the technology to overcome its original shortcomings, which were primarily related to range and weather conditions.

Rather than deploy the technology as a long-range solution, in which its light-based transmission was subject to degradation, SkyFiber keeps its links closer to about a mile, relying on mesh-based architectures to add range. Inclement weather can block optical transmissions, but SkyFiber has discovered specific frequencies and modulation techniques that allow its beams to punch through rain and fog. Additional forward error correction technologies add further fault tolerance, reinforcing the data transmission even in inhospitable conditions. “I only need 3% of that beam to go through to make a connection,” Achim said. “That gives me a lot of leeway.”

SkyFiber has even designed auto-tracking technology into its transmitters, allowing them to adjust for a building or structure’s sway, which could destroy a pinpoint optical signal.

SkyFiber is going to market not as an equipment vendor, but as a backhaul service provider using its own technology. Because it utilizes the visible light spectrum, it requires no licenses and can deploy all over the world and has no practical limit on capacity. Achim said that SkyLink will deliver up to 1.25 GB/s of capacity with four to five nines of reliability, and unlike microwave dishes, Skylink transmitters can be deployed side by side without interference issues. SkyFiber will offer links from 100 Mb/s to 1 Gb/s, though the same infrastructure will support the entire throughput range. Achim added that the technology also has a power advantage, using less than 35 watts of power, compared to the 100 watts of most microwave systems.

Though wireless operators looking for alternatives to fiber and radio backhaul will be SkyFiber’s prime target, it is also selling point-to-multipoint systems that can be used for fixed broadband access and mesh architectures that incorporate Wi-Fi for urban or campus metro wireless solutions. SkyFiber trialed the technology with a wireless operator in Mexico City, supplying up to 100 links to cell sites, and it has contracted with a Canadian mobile operator to build optical backhaul networks in six cities.