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The Latest in Li-Fi

Newly developed technologies are allowing wireless networks to operate several hundred times faster than Wi-Fi—one of them is Li-Fi or Light Fidelity. Simply by switching on a light bulb, it is possible to encode data within the visible light spectrum rather than allow them to ride on radio waves as traditional wireless technologies such as Wi-Fi do.

So far, research labs had confined Li-Fi within their closed doors. Of late, however, several new products using the Li-Fi technology has started to appear on the market. While the majority of the wireless industry focused their attention on developing 5G or the fifth generation wireless technology, PureLiFi presents a new dongle for laptops and computers that uses the latest light fidelity technology. Another startup company, Oledcomm from France, offers their Internet lighting system for hospitals and offices.

Light bulbs use LEDs, which are semiconductor devices able to switch at very high speeds, unlike the incandescent or fluorescent bulbs, which are rather slow in turning on and off. Li-Fi technology interrupts the electric current through the LEDs at high speeds, making them flicker and at the same time, encoding the light they produce with parallel streams of data. The analogy here is the process is very much like producing the Morse code in a digital manner, the difference being the flickering is much faster than the human eye can follow.

Dongles, smartphones, and other devices with built-in photo detectors can receive this light encoded with data. This manner of communication is not new, as remote controls have been using this technology using infrared lights. The remote sends tiny data stream commands to toys and televisions, and they interpret the information, process it, and change their functioning accordingly. Li-Fi uses visible light spectrum, as it can reach intensities capable of transmitting much larger amounts of data than infrared light can. For instance, it is common to find Li-Fi networks operating at speeds around 200 gigabytes per second.

The only downside to Li-Fi is it works on line-of-sight. As light does not bend around corners, the transmitter and receiver must physically see each other to communicate effectively. According to Harald Haas, the professor of mobile communications who introduced the world to Li-Fi, this handicap is easy to overcome by fitting a small microchip in every potential illumination device. The microchip would serve to combine two basic functionalities in an LED light bulb—illumination and wireless data transmission—one need only place the microchip embedded LED light bulbs in sight of one another to act as repeaters in between the transmitter and the receiver.

Haas spun out PureLiFi, whose initial products had a throughput of 10 Mbits per second, making them comparable to Wi-Fi versions available at the time. Since then, PureLiFi has advanced the technology to produce LiFi-X, an access point connecting LED bulbs and dongles and providing 40 Mbits per second for both downloads and uploads speeds.

Another company from Estonia, Velmenni, has already demonstrated Li-Fi technology in their products that offer speeds around one Gbits per second. Oledcomm has developed kits for retrofitting Li-Fi into existing LED light bulbs, useful for communication within supermarkets and retail stores.

Connect with a New Type of Li-Fi

Many of us are stuck with slow Wi-Fi, and eagerly waiting for light-based communications to be commercialized, as Li-Fi promises to be more than 100 times faster than the Wi-Fi connections we use today.

As advertised so far, most Li-Fi systems depend on the LED bulb to transmit data using visible light. However, this implies limitations on the technology being applied to systems working outside the lab. Therefore, researchers are now using a different type of Li-Fi using infrared light instead. In early testing, this new technology has already crossed speeds of 40 gigabits per second.

According to the Li-Fi technology, a communication system first invented in 2011, data is transmitted via high-speed flickering of the LED light. The flickering is fast enough to be imperceptible to the human eye. Although lab-based speeds of Li-Fi have reached 224 gbps, real-world testing reached only 1 gbps. As this is still higher than the Wi-Fi speeds achievable today, people were excited about getting Li-Fi in their homes and offices—after all, you need only an LED bulb. However, there are certain limitations with this scheme.

LED based Li-Fi presumes the bulb is always turned on for the technology to work—it will not work in the dark. Therefore, you cannot browse while in bed in the dark. Moreover, as in regular Wi-Fi, there is only one LED bulb to distribute the signal to different devices, implying the system will slow down as more devices connect to the LED bulb.

Joanne Oh, a PhD student from the Eindhoven University of Technology in the Netherlands, wants to fix these issues with the Li-Fi concept. The researcher proposes to use infrared light instead of the visible light from an LED bulb.

Using infrared light for communication is not new, but has not been very popular or commercialized because of the need for energy-intensive movable mirrors required to beam the infrared light. On the other hand, Oh proposes a simple passive antenna that uses no moving parts to send and receive data.
Rob Lefebvre, from Engadget, explains the new concept as requiring very little power, since there are no moving parts. According to Rob, the new concept may not be only marginally speedier than the current Wi-Fi setups, while providing interference-free connections, as envisaged.

For instance, experiments using the system in the Eindhoven University have already reached download speeds of over 42 gbps over distances of 2.5 meters. Compare this with the average connection speed most people see from their Wi-Fi, approximately 17.5 mbps, and the maximum the best Wi-Fi systems can deliver, around 300 mbps. These figures are around 2000 times and 100 times slower respectively.

The new Li-Fi system feeds rays of infrared light through an optical fiber to several light antennae mounted on the ceiling, which beam the wireless data downwards through gratings. This radiates the light rays in different direction depending on their wavelengths and angles. Therefore, no power or maintenance is necessary.

As each device connecting to the system gets its own ray of light to transfer data at a slightly different wavelength, the connection does not slow down, no matter how many computers or smartphones are connected to it simultaneously.

Wi-Fi or Li-Fi, What Should You Choose?

Although difficult to believe, but Wi-Fi is running out of steam, or more technically speaking, running out of spectrum. With almost all devices connected with Wi-Fi, our consumption of ever-increasing amounts of information is actually pushing the capacity of Wi-Fi to handle data, to its limits.

Presently, we use radio waves for transmitting information using Wi-Fi, but this method has its limits and it can only transfer so much at a time.

According to the latest estimates, by 2019, we will be exchanging roughly 30-35 quintillion bytes of data each month. We are already consuming huge chunks of radio frequencies and these are heavily regulated. That means Wi-Fi will be starved of bandwidth as data transfer amounts shoot up.

However, work is already underway at providing better technology for increased data transfers. Light Fidelity or Li-FI is showing great promise using light waves to transmit information. Scientists at Tallinn, Estonia, have conducted field tests to achieve speeds of 1GB per second. Although that is only about 100 times faster than traditional Wi-Fi, scientists in their labs claim to have achieved speeds up to 224 GB per second.

Apart from limited capacity, Wi-Fi arrangements are notoriously inefficient. For example, the base station responsible for generating the radio waves works only at about 5 percent efficiency, with the major part wasted as heat. A second part of the problem involves security, as Wi-Fi can penetrate solid objects such as doors and walls, raising concerns for those transmitting sensitive data.

Although light waves are a part of the same electromagnetic spectrum to which radio waves also belong, the difference lies in their wavelengths. Light waves use wavelengths more than 10 thousand times smaller than the wavelengths of radio waves. That means light waves have the capacity to carry enormous amounts of information as compared to radio waves, a fact already established by improved data transmission rates using fiber-optical technology.

However, Li-Fi uses a slightly different method of transmitting data. It works by flashing an LED light on and off at incredibly high speeds when sending data to a receiver. This is essentially sending binary code, only at ultra-high speeds. You will not see any flashes because the LED switches so fast. The communication is primarily line-of-sight, as light from the LED will not penetrate walls and other solid structures. That makes the technology endearing to those looking for security. A person sitting on the other side of the wall cannot eavesdrop on communication using Li-Fi, as they can with the one using Wi-Fi technology.

We already use illumination devices in our homes, and this could double up as potential communication devices as well. What is necessary is to fit a small microchip to every light bulb to convert it into a wireless data communication hub, while also providing the necessary illumination. In other words, we already have the infrastructure in place. The LED bulbs in use in our homes and offices, with some tweaking, can work as incredibly high-speed high volume data transmission and receiving devices.

Why is Li-Fi better than Wi-Fi?

Imagine wandering through an art gallery with your PDA. As you reach an interesting canvas, your PDA starts downloading information about the painting. When you move to another, your PDA displays content relative to the current piece of art. This is called content fencing – tailoring information to specific locations so that users receive information relevant to their current location.

Content fencing is impossible to achieve with Wi-Fi – radio waves have a far greater spreading power. However, this is eminently possible if electromagnetic waves of very short wavelength – such as optical beams – are used. We already have the necessary technology with us and it only requires converting LED bulbs into wireless access points as an equivalent of a wireless network. This is LI-Fi, allowing you to move between light sources for effectively remaining connected. At present, Li-Fi is only a complementary technology compared to Wi-Fi, but its potential benefits over Wi-Fi are huge.

Visible light spectrum has a huge bandwidth compared to the RF spectrum – in excess of 10,000 times. Moreover, visible light spectrum is unlicensed and free to use. RF tends to spread out over a large area causing interference, whereas, visible light can illuminate a tight area and can be well contained. This allows Li-Fi to attain over a thousand times the data density than Wi-Fi can achieve.

Low interference means more data can be transferred. Therefore, Li-Fi achieves very high data rates and devices using Li-Fi can have high bandwidths along with high intensity optical output. With illumination infrastructure already available in most places, it is relatively easy to plan for introduction or expansion of Li-Fi capacity with good signal strength.

The presence of illumination infrastructure also means negligible additional power requirements for Li-Fi, more so because LED illumination is inherently efficient. In comparison, radio technology requires additional components and energy to implement. Li-Fi works very well in water, but it is extremely difficult to implement and operate Wi-Fi underwater.

Even today, there is a raging debate about whether RF transmission is safe for life on Earth. Visible light does not court such controversy regarding health and safety, as it is the Sun’s rays that sustain life on Earth. Moreover, in certain environments, radio frequencies are considered dangerous as they can interfere with electronic circuitry. That is why people are asked to switch off their phones in flight.

The closely defined illumination area makes Li-Fi very difficult to eavesdrop. Unlike Wi-Fi that spreads its signals all over, even passing through walls, Li-Fi signals are confined to a specifically defined area. This makes Li-Fi far more secure as compared to Wi-Fi. Moreover, data flow in Li-Fi technology can be visibly directed according to requirement. You only need to point one device towards another to make them communicate. That makes it unnecessary to add a layer of security such as pairing, as is required for a Bluetooth connection.

Considering that LEDs operate more than 50,000 hours, it is necessary for manufacturers to add new services to the light they sell. Li-Fi offers massive new opportunities and myriad of different applications for the future communications market.

Connecting to the web via LEDs: Li-Fi

Connecting to the Internet is best done through copper wire or high-speed wireless connections. Not many are aware of an additional method – using light beams. This is accomplished not by the usual optical fiber stuff, but by using LEDs. Communication with lights is nothing new – it has been done before. The Scottish scientist, Sir Alexander Graham Bell had invented an arsenal of instruments for communication and these included Photophones.

The first instruments to use light for communication were Photophones. Now, after about 110 years after the invention of photophones and their fading into history, Professor Harald Haas is conducting experiments in wireless communication using light-centric technology. At the University of Edinburgh in Scotland, Professor Haas is using the Alexander Graham Bell building for his experiments.

Professor Haas demonstrated his vision for the future of wireless communication way back in 2011. He was using something as simple as LED bulbs for his experiments. This is also the time when the term Li-Fi was coined. Li-Fi is now used to describe bidirectional networked wireless communication using visible light as a replacement for traditional radio frequencies.

With people implementing the Internet of Things in full swing, it will not be very long before there is a spectrum crunch for the radio frequencies. In this context, light modulation and enabling connectivity through simple LED bulbs will have huge ramifications. Li-Fi can allow you to connect to the Internet as soon as you are within the range of an LED beam. Even your car headlights can be used to transmit data.

Professor Haas is working towards PureLiFi, which can offset the global struggle for the vanishing wireless capacity. PureLiFi is striving to develop and drive technology suitable for secure, reliable and high-speed communication networks. This will help to integrate data and lighting utility infrastructure seamlessly while reducing energy consumptions significantly.

One of the most interesting features of Li-Fi is its security over the conventional networking methods. Although Li-Fi is not yet available on the Internet marketing websites, companies from the security-focused fraternity are highly interested parties. That is because prying eyes of third-parties find Li-Fi significantly harder to infiltrate compared to other current networking technologies.

Li-Fi signals travel over narrowly focused beams and they cannot penetrate walls. Additionally, with LED lights, you have natural light beams; therefore, the uplink and downlink channels can be separated leading to increased security. For example, if you are browsing using two-channel Li-Fi, both beams will have to be intercepted for someone to infiltrate into your computer, provided they first gain entry into the same room as you are in.

In practice, Li-Fi networks use a desktop photosensitive unit to communicate with an off-the-shelf unmodified light fixture using infrared LEDs for its uplink and downlink channels. Within a range of about three meters, you can have uplink and downlink channels delivering a typical capacity of 5Mbps. With Li-Fi, it is possible to achieve speeds as high as 10Gbps as well. As an additional benefit, your workspace remains well lit.

Li-Fi allows you to have your content tailored before delivery. Within a single room such as in an exhibition, you could wander through various beams to pick up information relevant to your current location.