Free-space optical communication
“Free-space optical communication presents an opportunity for delivering high-speed internet access to the half of the world’s population that is currently without, provided that some of the implementation issues can be overcome.” Anne Margaret Crow, TMT analyst
What is free-space optical communication?
Free-space optical communication (FSOC) uses lasers to move data through the air and the vacuum between satellites without the need for cables. An adaptation of current-generation fibre optic broadband, the technology is in its infancy and is mostly used by governments for military and emergency purposes.
FSOC is attractive to governments as they do not need to apply for Federal Communication Commission (FCC) authorisation for FSOC’s difficult-to-intercept narrow transmission beam and high bandwidth networks. That said, as demand for internet bandwidth grows more companies are exploring how FSOC can be used commercially.
What is driving demand for free-space optical communication?
FSOC demand is driven by western consumers’ seemingly insatiable demand for data as existing networks in developed regions struggle to increase their capacity. In its 2017 white paper, Cisco forecasts that global IP traffic will reach 3.3 Zettabytes (Zb), a measure of data defined by one sextillion bytes, by 2021, up from 1.2Zb in 2016. This threefold increase over five years is equivalent to a compound annual growth rate (CAGR) of 24%.
However, half of the world’s population still has no access to the internet due to the monetary or logistical hurdles of current-generation internet infrastructure. It is this set of potential consumers that big tech companies like Google, Facebook and Amazon are keen to monetise.
Can non-FSOC technologies meet the growing demand for data?
One solution to the growing need for network capacity is simply installing more fibre optic cabling, but fibre optics are uneconomic in sparsely populated or inhospitable regions. The solution more apt to work in remote areas is increasing existing microwave satellite coverage.
In the short term this is the solution most operators will implement, but as demand for data grows, the poor transmission rates of microwaves, 1,000 times slower than laser communication, may push FSOC into a more prominent role.
What are the major advantages of free-space optical communication?
FSOCs are not only better than microwaves due to their high capacity/frequency and broader bandwidth, but they are well suited to airborne and satellite networks due to their modest power requirements. This is an important factor in all satellites, especially the increasingly popular smaller variants that range from low earth orbit microsats, like those serviced by AAC Microtech, to modular Cubesats.
In addition, the narrow nature of FSOC’s transmission beams means they are less likely to interfere with other laser links nearby, disposing of the need to obtain an operating licence from the International Telecommunication Union, a mandatory requirement of microwave communication that slows down network implementation.
Which companies are developing free-space optical technology?
As an innovative technology few companies are developing FSOCs, of which Tesat-Spacecom, Thales and Mynaric are the most advanced, with BridgeSat starting to catch up with competitors.
Tesat-Spacecom, a subsidiary of Airbus, provides the German Aerospace Center with laser links for governmental purposes. Tesat also provided the backbone of the newly operational European Data Relay System (EDRS), a relay network that the EU hopes will accelerate the European communication network by relaying data between satellites. Thales is involved to a lesser degree in the EDRS as it speeds up its move away from government-sponsored programmes to more commercial activity.
Myranic is also focused on the commercial market, working with Airborne Wireless Network (AWN) and other space-borne partners. And BridgeSat, fresh from series A funding in 2017, expects to have three ground stations fully operational by the end of 2018.
What are the plans for large-scale airborne networks in the near future?
Google plans to broaden its user base by providing internet access through Project Loon. The project involves the launch and maintenance of more than 100 high-altitude communications balloons to provide internet coverage to people in rural and remote areas.
Facebook’s Connectivity Lab hopes to construct the first fully functional commercial airborne network, using its Aquila high-altitude long endurance (HALE) aircraft and laser communications platform. When complete, the autonomous platform will circle a region 60 miles in diameter, staying airborne for up to three months at a time.
Finally, OneWeb, in its constellation of 7,500 Ka/Ku band satellites, plans to use optical links to connect satellites in orbit. However, delays have forced the company to shift the launch of its first 10 satellites to the end the year.
Download PDF