Previous blogs have focused on the why, who and how of the new constellations but one of the key questions surrounding all of these constellation developments is how do you inter-connect hundreds – then thousands – of satellites, drones, high-altitude platforms or aircraft so they deliver a fully world-wide canopy of coverage?
Once a number of satellites are launched and in low Earth orbit – and some of the numbers we are talking about are quite astonishing; Space X alone will eventually have over 11,000 satellites circling above us – there needs to be a critical link between those satellites or drones or aircraft. But what interconnecting technology will create this mesh network that will form these constellations?
There is really only one serious contender that can future-proof these constellations being launched into low Earth orbit: lasers. The innate benefits that laser communication wields over existing RF communication (radio technology) is increasingly meaning that telecommunication companies are increasingly opting for lasercom as the technology of choice for their new constellations.
Now, you are probably immediately thinking: But aren’t they scary things to wallop the wrong ‘uns in Star Wars with, or pocket-sized keychains with enough blinding power to dazzle pilots of jumbo jets coming in to land, or worrisome devices used to correct myopia?
In each of the three cases above, yes, but, in mitigation, it is more the human operating the laser than the laser itself that poses the danger – you want to see my six-year-old son go at it with his light sabre. Now that is scary…
Laser communication can provide high-speed backbone connectivity for high-altitude and spaceborne constellations
But laser communication is being considered as the future of backbone connectivity for these constellations for myriad reasons.
In spite of the frivolous examples above, lasers – as used in communication scenarios – are largely harmless to humans. The low laser power, at 1550 nm wavelength, means that it is regarded as “eye safe”, the beam narrowness also makes this form of communication so secure.
An RF beam – and these RF beams are how satellites currently communicate with ground stations – spreads out like a fan from its origin whereas lasers maintain their narrow shape over vast distances. And this makes them near-impossible to tap, jam or spoof – no eavesdropping.
Data transfer rates and lower cost-per-bit make laser communication the only choice for constellation builders
Another key benefit over RF is the increased bandwidth available. The current record data transfer achieved by millimeter wave technology, that is the current state of the art radio technology, is 40 Gbps. Compare that with the current record for laser communication – a mere 13,160 Gbps – and you start to understand that future-proofing the technological and financial viability of these constellations is really only achievable with lasers.
These developments also impinge on cost, which makes laser cost-per-bit appreciably cheaper than RF-provided cost-per-bit: another fundamental business consideration for those launching satellites to eventually sell the bandwidth of their networks to enterprises and consumers.
Lasercom means an end to regulation and red tape
And existing radio frequencies involve lots of red tape. Before you even start thinking about launching your satellite you need to apply for a license from every country you want to send an RF beam down to. You have to pay the costs associated with each licensing regime and then you have to wait. And wait. And then, in about a year, you might – just – be ready to launch your satellite and start your broadband service. However, laser communication is not regulated by the International Telecommunication Union and can be used without restrictions thanks to its inherent safety. Another major factor leading constellation-builders down the laser communication route.
As the internet matures so it demands numerous technological developments to keep pace with it and allow it to keep moving in the direction that it has been traveling in since its inception. Future-proofing systems that will cost billions to establish is essential: if it takes 5-6 years to put in place an LEO constellation, what use is it if it is unfit for purpose or technologically defunct once it is operational. It is incumbent on constellation-builders to ensure that a network’s backbone connectivity provides what is predicted to be an exponentially high, Malthusian proliferation of devices not just demanding data and high bandwidth data but also ubiquity of availability.
Whilst moves along the RF spectrum are seeing faster speeds come online all the time, the real interest of telecommunication companies lies in laser’s ability to satisfy global reach, upmost network capacity and unprecedented security.
It is, as some have described it, the optical-fiber for the skies.
It is, as we believe, the future of telecommunications.
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