Wait Until Day: At 1GB/min, Li-Fi 100x Faster Than Wi-Fi, But Limited

“I believe that the biggest threat to the future of mobile in America is the looming spectrum crisis,” said Julius Genachowsky, the chairman of the FCC, in 2009. The sentiment behind that statement arose from faulty researches conducted by the CTIA, and peddled by network corporations, which projected that an explosive growth in mobile data consumption would lead to a spectrum crunch. Basically, the spectrum of frequencies licenced to corporations would simply not fulfil “increasing demand” for data. Since spectrum is finite, the solution was to make more bands of frequency, which are regulated by governments, available, as opposed to efficiently using un/under-utilised spectrum, or, perhaps, building better technology and infrastructure.

Years later, the threat of an “inevitable” exaflood drowning out wireless capacity turned out to be trumpery. But what the politics around this hype did generate was an even more increased interest in safer, more secure and far more efficient means of data transmission.

That’s where scientist Harald Haas steps in, the current Chair of Mobile Communications at the University of Edinburgh and co-founder of PureLiFi Ltd. For 20 years, Haas has worked to study and experiment wireless communication. Then, in 2006, he published his first paper on the wireless communication through visible light communication or VLC (Afgani, Haas, Elgala, & Knipp, 2006). Later, Haas would christen this technology Li-Fi (light fidelity), and introduced it to the world at TED Global in 2011. A year later, he established PureLifi a year later.

Very simply put, Li-Fi uses visible light spectrum to transmit data instead of traditional radio frequencies your laptops, tablets and phones are built to detect. Light is already used to transmit data through gossamer silica fibres, but Li-Fi doesn’t require cables.

Even a superficial comprehension of Li-Fi makes its benefits obvious. It can be seamlessly integrated into infrastructure; it is reliant on LEDs, which are energy efficient; it is faster (PureLifi’s has demonstrated communications at 100 GBPS); the visible spectrum of light cannot be licenced, so it’s cheaper than Wi-Fi; though large-scale installation would be expensive, maintenance cost is greatly reduced.

Every LED light can be essentially converted into a data transmitter. The data itself is transmitted through rapid fluctuations in brightness invisible to the naked eye. Since your device itself cannot make sense of this data-loaded light, the encoded information is received via solar photo detectors. As light fluctuates so does energy harvested in the solar receptor. According to Haas’ September TED talk, a “standard, off-the-shelf solar cell” can transmit up to 50 MBPS.

Haas says,

‘What’s really important here is that a solar cell has become a receiver for high-speed wireless signals encoded in light, while it maintains its primary function as an energy-harvesting device. That’s why it is possible to use existing solar cells on the roof of a hut to act as a broadband receiver from a laser station on a close by hill, or indeed, lamp post.’

Currently, radio waves make our data sharing environment, but they have big problems: they’re expensive, they cost money to maintain and making them energy efficient is still work in progress. The nature of radio waves also make them susceptible to interception by unauthorised users. The last one would be especially important to home users concerned about the security of their wireless connections. Until a now, radio waves were our only option, because, “you don’t want to get close to gamma rays, it could be dangerous. X-rays, useful when you go to hospitals. Then there’s ultraviolet light. it’s good for a nice suntan, but otherwise dangerous for the human body. Infrared — due to eye safety regulations, can be only used with low power,” says Haas.

It’s ironic that it has taken the post-Industrial man more than a century to realise the source of life, an energy worshipped for thousands of years, could be the answer to all of life’s problem.

This isn’t to say Haas believes Wi-Fi should be completely phased out, but that our reliance on it, especially in closed spaces, would be supplemented by Li-Fi. And that’s a clever statement to make because of limitations inherent to VLC itself. Unlike radio frequencies, VLC isn’t hindered by interference, but without light, you won’t have a connection to begin with. Though communications can be maintained in dimmer lights, speed of transmission will gradually reduce. Reflected light will also reduce it. Li-Fi also has issues with coverage due to light’s inability to penetrate solid surfaces: this can be a coverage disadvantage or security advantage. Most importantly, and this might be what concerns Internet users most, unlike radio frequencies, there’s really no way right now for your device to communicate back with an LED transmitter.

Haas says, “If the light signal is blocked, or when you need to use your device to send information — you can seamlessly switch back over to radio waves.” He further adds, “We still need Wi-Fi, we still need radio frequency cellular systems. You can’t have a light bulb that provides data to a high-speed moving object or to provide data in a remote area where there are trees and walls and obstacles behind.”

Newspapers have been having fun declaring Li-Fi the best disruptive technology of the decade. There is a funny irony in that TED, which has hosted Haas twice, boldly claims – “Harald Haas: Forget Wi-Fi. Meet The New Li-Fi Internet”. Haas’ statements itself are opposed to what the viral headline declares. The people behind it see it as a technology complementary to Wi-Fi, especially for off-loading downlink traffic. If anything, VLC, in conjunction with RF, would help clean up the wireless communication network in terms of congestion and cost.

Research has been underway on Li-Fi for a while now by universities and startups, including the development of technicolour wireless signals. What remains to be seen is how fast and how soon Li-Fi will become a reality for corporate and home users, and to what extent, considering its eyebrow-raising drawbacks.

Some technological problems will likely be solved as Li-Fi is further developed to become commercially viable, but Wi-Fi, until something near-faultless is invented, is here to stay for a long time.

What we can certainly look forward to are siblings turning the lights off on each other during movie time.

Read more about Li-Fi here.

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