What The New Li-Fi Standard Offers The Telecoms Ecosystem

July 19, 2023

Written by Alex Lawrence

In June the IEEE ratified the 802.11bb standard to relatively little acclaim. However, this standard opens up some pretty exciting possibilities.

Firstly, this standard is for Li-Fi operating in near-infrared, outlining the physical layer and system architecture. Li-Fi has been a work in progress on the fringes of telecoms for years, with successful applications in a number of settings. However, this is the first time that Li-Fi has had a global standard to build momentum – and an ecosystem – around.

Standard Bearers

Moreover, as the IEEE manages the Wi-Fi standards too, there is talk about the complementarity or interoperability of Li-Fi and Wi-Fi.

Direct interoperability seems like a stretch, given the very different frequencies at play, but antennae aside this might offer opportunities for Wi-Fi manufacturers to re-tool fairly straightforwardly to serve Li-Fi use cases.

Some commentators have questioned whether Li-Fi will take off, highlighting the lack of a strong ecosystem as matters currently stand. However, bringing Li-Fi within the 802.11 family has likely gone a good way towards enabling the growth of an ecosystem. 

Li-Fi has some unique capabilities which are not shared by Wi-Fi. One of the current uses for it relies on its inability to penetrate most objects, which means that data cannot be intercepted through walls. This both increases the security of the data being transmitted wirelessly and means that, within a building, the spectrum can be re-used from room to room with minimal, if any, interference.

With a projected growth in demand for high-capacity services, this would improve the performance of networks. Actually, building out a Li-Fi network is relatively straightforward, with smart bulbs backhauled either through powerline communications or ethernet depending on the property involved.  

As with the sub-THz bands being mooted for use in 6G communications, Li-Fi can also be used for sensing with a fine resolution (a few centimetres, the standard claims). Something like this could offer some novel use cases, such as being used in prisons to monitor whether or not prisoners are breathing – ensuring alerts in cases of suicide or medical emergencies. Coming some years before 6G standards, this offers a complement or alternative to use cases in the sub-THz band.

That near-infrared spectrum ranges from roughly 300 THz to 375 THz, which is orders of magnitude more than is available in most bands and is a globally unlicensed swath of spectrum.

The initial Li-Fi specification is intended to provide data rates of up to 9.6 GB/s, which is roughly equivalent to the best performances of Wi-Fi 6. The first generations of Wi-Fi, by contrast, were operating in the tens of KB/s.

While Li-Fi has undoubtedly benefitted from the lessons and advances in, for example, processor technology since then, it’s a striking indicator of the scope Li-Fi has to become more efficient for the spectrum available.

This is not the only use of the optical spectrum. In an interview with 6GWorld last year, PureLiFi CEO Alistair Banham pointed out that lessons from the fibre optic industry have given Li-Fi manufacturers valuable examples to improve their performance.

Meanwhile, Alphabet’s Project Taara has been developing communications in optical frequencies using lasers for point-to-point, high-capacity links. Originally conceived as part of Project Loon, Taara is being tested in a variety of African environments as an alternative to fibre installation, for example for several kilometres across the Congo River from Brazzaville to Kinshasa.

The same technology is being tested for communications between satellites, beyond the reach of atmospheric effects such as fog and rain which can impair transmission of optical signals at ground level.

Free Space Optical Networks, or FSONs, like Taara’s and others, are not included in the Li-Fi standard; nor, naturally, is the signalling within fibre networks. However, there is clearly scope for overlapping the different technologies depending on the use case. For example, high-capacity laser as a point-to-point solution may be useful in indoor industrial environments as an alternative to permanent fibre connections, enabling more flexible and dynamic manufacturing chains.

Drawbacks

Critics have pointed to the lack of Li-Fi receivers in mobile handsets as a point against widespread uptake of the system, and that is true. It would be difficult to benefit from Li-Fi while the phone is in a pocket, for example.

However, this is not the case with other device types, either current or emerging. XR glasses would be by their nature much more exposed, making Li-Fi a more viable means of communication with them.

Cars already have a wide range of sensors and bulbs built in, so high capacity V2X communications and sensing in the near-infrared would be an option – both to communicate from and to an individual vehicle, and to support a mesh network backhauling to specific roadside access points.

A lack of an established ecosystem is something we see in the higher frequencies being proposed by 3GPP as well. Where are the manufacturers pushing out 6G antennas, chipsets, and devices? Nowhere, as of yet, but this is not highlighted as a problem in and of itself; it’s just a symptom of the point in the lifecycle of the technology. The fact that there are manufacturers of Li-Fi solutions at all today puts it a step ahead.

None of this means that mass demand for Li-Fi will come to pass, of course. However, there was a similar reaction to Wi-Fi when it first emerged, followed by a good deal of worry from telecoms providers that it would take away “their” customers before the status quo finally settled.

Li-Fi will almost inevitably become another tool in the technologists’ utility-belt of connectivity methods. Even if it does end up only filling niche use cases, just having the standard offers advantages.

Making large additional swathes of unlicensed spectrum available for use may change some of the calculations around pricing licensed spectrum in the Sub-THz range, for example.

If joint sensing and communications can be performed through Li-Fi, why pay to do it in sub-THz? While sub-THz has better propagation than Li-Fi through some materials, it’s still pretty awful. There are use cases where one frequency range is better than the other, but will they be significant enough to justify the kinds of prices we saw in auctions for 5G? I’m not sure many operators could justify that, and having a license-free alternative is a good basis to negotiate prices down.

Overall, it’s going to be fascinating to see how the market for Li-Fi develops in the next couple of years and how this coincides or collides with the development of 6G standards in 3GPP.

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