What is Li-Fi?

LI-FI. A New Era of Wireless Technology.

Will Li-Fi replace Wi-Fi?

 

Li-Fi , as coined by Prof. Harald Haas during his TED Global talk, is bidirectional, high-speed and fully networked wireless communications, like WiFi ,using visible light. Li-Fi is a subset of Visible Light Communications (VLC) and can be a complement to RF Communications.

Li-Fi is designed to use LED light bulbs similar to those currently in use in many energy-conscious homes and offices. However, LiFi bulbs are outfitted with a chip that modulates the light imperceptibly for optical data transmission. LiFi data is transmitted by the LED bulbs and received by photoreceptors.

Li-Fi’s early developmental models were capable of 150 megabits-per-second (Mbps). Some commercial kits enabling that speed have been released. In the lab, with stronger LEDs and different technology, researchers have enabled 10 gigabites-per-second (Gbps), which is faster than 802.11ad.

 

Benefits of Li-Fi
  • Higher speeds than WI-FI
  • 10000 times the frequency spectrum of radio.
  • More secure because data cannot be intercepted without a clear line of sight.
  • Prevents piggyback.
  • Eliminates neighboring network interference.
  • Unimpeded by radio interference.
  • Does not create interference in sensitive electronics, making it better for use in environments like hospitals and aircraft.

By using LiFi in all the lights in and around a building, the technology could enable greater area of coverage than a single WIFI  router. Drawbacks to the technology include the need for a clear line of sight, difficulties with mobility and the requirement that lights stay on for operation.

How Does Li-Fi work ???
How_VLC_works

When a constant current is applied to an LED light bulb a constant stream of photons are emitted from the bulb which is observed as visible light. If the current is varied slowly the output intensity of the light dims up and down. Because LED bulbs are semi-conductor devices, the current, and hence the optical output, can be modulated at extremely high speeds which can be detected by a photo-detector device and converted back to electrical current. The intensity modulation is imperceptible to the human eye, and thus communication is just as seamless ad RF. Using this technique, high-speed information can be transmitted from an LED light bulb.

 

Radio frequency communication requires radio circuits, antennas and complex receivers, whereas Li-Fi is much simpler and uses direct modulation methods similar to those used in low-cost infra-red communications devices such as remote control units. Infra-red communication is limited in power due to eye safety requirements, whereas LED light bulbs have high intensities and can achieve very large data rates.

 

Imagine ourselves walking into a complex where GPS signals are unavailable but the complex is equipped with ceiling bulbs that create their own ‘constellation’ of navigation beacons. As the camera of our cell phone automatically receives these signals, it switches our navigation software to use this information to guide us to the ATM machine we’re looking for. We conclude our ATM transaction and notice the Giga Spot sign for instant digital movie downloads. We pick out that new data using our phone’s payment facility and then download within a few seconds the high-definition movie into the Giga Link flash drive plugged into the USB port of our Smartphone. As we walk away, our phone notifies us that the leather jacket featured in the character of movie is on sale nearby. We walk over towards the show window and our image comes up on the screen, wearing that coveted jacket. You turn and pose while the image matches our orientation and body gestures for a ‘digital fitting.’ When we walk into the store, the clerk hands over the jacket in exactly the right size.

 

Access Internet Through Li-Fi

Li-Fi signals are confined to narrowly focused ‘beams’ that don’t travel through walls. Moreover, LED lights are natural beam-formers, which makes it easier to create separate uplink and downlink channels, which essentially means more secure internet browsing, given that both channels have to be ‘intercepted’ if someone did manage to coerce their way into the same room as you.

“This [Li-Fi] is a technology that can aid cybersecurity in a very new way,” says Haas.

The Li-1st allows you to network via a desktop photosensitive unit that works in tandem with an off-the-shelf, unmodified light fixture. The desktop unit has infrared LEDs to communicate in the uplink channel. We were given a demo by Haas in his light emporium at the University of Edinburgh, and the YouTube video we watched streamed flawlessly.

The Li-1st delivers a capacity of 5Mbps in the uplink and downlink channels, covering a range of “up to” three meters. And yes, you benefit from a nicely lit working space too. It’s worth noting here that it has been shown that Speeds up to 10 GBPS has been proven with Li-Fi too.

While Li-Fi could become a more common fixture in security-conscious locations in the future (e.g. banks or government buildings), there are innumerable potential use-cases.

Content can be tailored to specific locations through ‘fencing’, so that you know exactly what people and places are receiving what kind of data – even within a single room. Someone could even wander through various beams and receive information relevant to where they currently stand.

So this is a potential scenario: Lots of spotlights in a room, with people wandering along with their tablet, passing through various beams, and the connection remaining constant throughout. And it’s this exact thing that PureLiFi is working on next – the Li-Flame will create the equivalent of a wireless network by turning LED bulbs into wireless access points, effectively letting you move between light sources without losing your connection.

The Li-Flame will also feature a mobile unit that you can attach to your portable device, thus making it compatible with LED connectivity.

lifi_environment

Light for WiFi communication

 

  • Visible light communication(VLC) uses rapid pulses of light to transmit information wirelessly.
  • It may be ready to compete with conventional WiFi.
  • LED light is inherently safe to use and would be great if we can also use it for wireless communication.

 

lifi_vs_wifi_1128

Almost everyone uses Wi-Fi every day and Bluetooth every so often. But these wireless technologies have a fatal flaw: they use radio waves to communicate. The problem with radio waves is that, although they offer decent speeds, they transmit data slowly, and the signal is often blocked or affected by equipment as simple as the microwave in your kitchen. However, a team of scientists are hard at work developing a new, extremely fast method of wireless communication, and it doesn’t use radio waves; it uses light from LED bulbs.

Light-based wireless communication, coined by Harald Haas at a TED talk in 2011, is a method of internet connectivity that doesn’t use cables or radio waves, instead flickering the light from a special LED to transmit data just like your Wi-Fi adapter would.

Wi-Fi works by spewing out radio waves in all directions around your home or business from a wireless router. When your wireless device, such as a smartphone, detects the wireless radio waves, it connects to your wireless router, which then connects you to the Internet. The idea behind Li-Fi is almost identical, but instead of wireless radio waves being sent in all directions, it instead sends light shooting out to connect to your smartphone, laptop, or other devices. You wouldn’t even notice, but your LED lights would flicker at high-speed, sending data all around your house.

The difference between Li-Fi and Wi-Fi though is that Li-Fi is much more secure. Li-Fi can only work when your device can detect the light being emitted by the Li-Fi router, meaning it will only work if you’re in the same room or area the light is being emitted. This means people passing by cannot connect and piggyback off of your Internet connection. And did we mention that it is unaffected by RF-emitting equipment operating in the same room, such as a microwave or radio?

Li-Fi is also much faster; the latest Wi-Fi standard, 801.11ac, has a maximum speed of about 867 Megabits per second for a typical handheld. Li-Fi, meanwhile, can reach speeds up to 3.5Gbit/s per color – meaning a typical Red-Green-Blue (RGB) LED can emit speeds up to 10.5Gbit/s – more than 10 times faster than the latest Wi-Fi technology. These speeds offer a lot of potential for wireless connectivity.

What you also may not know is that light already is the most popular means to transmit data across long distances. Fiber optic cables send data as light through tiny strands of silicon. Fiber optics are the arteries of much of the modern internet, allowing fast transmissions of data around the world. Li-Fi uses light just as fiber optics do to transmit the information, but instead of maintaining it through the thin strand of fiber, it allows the light to spread out in all directions so devices all over the room can connect.

While it may be a few years before we see this technology in our homes, the potential is impressive. Even laboratory testing behind this new Li-Fi technology is showing great promise and speeds way beyond what Wi-Fi can handle in any real-world environment. If Li-Fi continues to perform well, the idea of having any wired internet at home may soon become a distant memory.

Of course, this also means that if you want to watch your iPad in bed, you may need to keep the light on.

Conclusion:

Li-Fi is an upcoming technology that may replace conventional Wi-Fi.  LED Light is an ultra low-cost source of energy, and the use of LiFi reduces radiation exposure associated with traditional WiFi signals. The possibilities are numerous and can be explored further. If this technology can be put into practical use, than hypothetically every bulb can be used for something like a Wi-Fi hotspot to transmit wireless data and we will proceed towards a cleaner, greener, safer and brighter future.

 

Senior Editor at Elite Computing Concepts
Hima, founder of Tech Wonder.in, is an MSCS student at Bankatlal Badruka College for Information Technology (BBCIT). He brings a wealth of knowledge on international technology innovation and joins us as Senior Editor of our Technology Blogs.
  • E techsite

    A good article about LI-FI 🙂 Great Info

    • ecclogic

      Thank you! Yes Hima wrote an excellent piece for us. Please feel free to check us out on Facebook, Twitter, and Google+, just click the buttons on the right! Thanks!!