Li-Fi technology (super-fast Internet on LEDs): overview, description, device and prospects

Li-Fi is a new data transmission technology that will radically change the business in the future, create opportunities that have matured for use today, and is preparing to become a multibillion-dollar industry by 2022. Currently, the development of 1Gbit / s speed is being developed, which will allow to exceed the indicators of ultra-fast broadband access.

Information light

The term Li-Fi was coined by Professor Harald Haas and refers to a method of broadcasting information using light that provides high-speed bi-directional mobile communication, similar to Wi-Fi. It can be used both for unloading existing networks operating at radio frequencies, and for increasing their throughput.

For ultrafast communication, the visible part of the electromagnetic spectrum is used. This distinguishes this technology from such an established form of wireless communication, like Wi-Fi, which involves traditional frequencies.

In Li-Fi, the data is transmitted by modulating the light intensity, taken by the photodetector, and the signal is converted into an electrical one. Modulation is done in such a way that the human eye does not perceive it.

The technology of high-speed optical communication Li-Fi belongs to the category of wireless communications, which, in addition to visible light, includes infrared and ultraviolet. Its uniqueness lies in the use of existing lighting networks.

Li Fi - ultra-fast internet on LEDs

When a direct current is applied to an LED lamp, it emits a stable flux of visible light photons. When the current is decreased or increased, the brightness of the glow also changes. Since LED bulbs are semiconductor devices, the current and therefore the optical output can be modulated at very high speed. It can be adopted by a photocell and converted back to an electric current. Modulation of brightness is imperceptible to the human eye and is just as convenient as radio. Using this technique, the LED lamp is capable of transmitting information at a high speed.

Radio frequency communication requires the presence of electrical circuits, antennas and complex receivers, while Li-Fi technology is much simpler. It uses direct modulation techniques similar to those used in inexpensive infrared communication devices - remote controls. The use of infrared communication is limited due to the requirements of sanitary safety standards of the eyes, while LED lamps have a high intensity of luminescence and demonstrate a significant speed of operation.

Light or radio?

Li-Fi can turn a lamp into a wireless access point, similar to a Wi-Fi router.

In the traditional connection, radio frequencies are used, but their number is very limited. Devices - computers, laptops, printers, smart TVs, smartphones and tablets - must compete for bandwidth. The emergence of an increasing number of things using Wi-Fi, such as refrigerators, clocks, cameras, cell phones, is the cause of delays and a reduction in the data transfer rate. Li-Fi technology uses frequencies of light waves, which are 10,000 times greater than radio frequencies.

Radio waves create electromagnetic interference that interferes with the operation of devices and equipment of aircraft, hospitals and potentially dangerous in such industries as nuclear power engineering, drilling of oil and gas wells. Li-Fi uses light that is intrinsically safe and does not create electromagnetic interference.

Radio waves pass through walls and ceilings. The light does not. This is the difference in the protection of data between Wi-Fi and Li-Fi. A hacker outside the building is able to connect to the radio network inside it. Data transmitted via Li-Fi is available only where the lamp is shining.

The standard Wi-Fi 802.11a / g provides a transmission speed of up to 54 Mbps, and this value can be increased to 1 Gbit / s. The University of Edinburgh has already reached 3 Gbit / s in monochrome. One full-color RGB-LED can transmit up to 9 Gb / s.

Internet from a light bulb Li-Fi

The development of this technology contributed to a sharp increase in the use of LEDs for lighting purposes.

Li-Fi is perfectly suited for downloading video and audio, live broadcasts, etc. These tasks impose high demands on the bandwidth of the input channels, but require a minimum outgoing power. Thus, most of the Internet traffic of existing radio-frequency channels is freed, expanding the possibilities of cellular communication and Wi-Fi.

Luminous Internet Li-Fi is used in a variety of areas:

• Release of radio frequencies: peak loads of cellular networks can be shifted to Li-Fi. This is especially effective on the input communication channels, where bottlenecks occur most often.
• Smart lighting: any private or public lighting, including street lights, can be used as Li-Fi access points, with the same communications infrastructure and sensors.
• Mobile connections: laptops, smartphones, tablets and other mobile devices can directly connect using Li-Fi. A short distance provides excellent and secure communication.
• Dangerous production: Li-Fi technology is a safe alternative to electromagnetic interference from radio frequency communications at facilities such as mines and petrochemical enterprises.
• Medicine and health care: light does not create electromagnetic interference and therefore does not interfere with medical equipment, and is also not affected by MRI scanners.
• Aviation: Li-Fi can be used to reduce weight, reduce the length of the wiring and increase the flexibility in seating equipment placement of the passenger compartment where the LED fixtures are already installed. The entertainment system on board is capable of being maintained and interacting with the mobile devices of passengers.
• Communication under water: due to strong signal absorption, the use of radio frequencies in water is not practical. Acoustic waves have very low throughput and disturb marine animals. Li-Fi technology provides a solution for short-range communication.
• Vehicles and transport: headlights, taillights, street lights, signs and traffic lights are already being produced, in which LED lamps are used. This makes it possible to communicate between cars and road infrastructure in safety and traffic management systems.
• High-precision, local information services, such as advertising and navigation, which allow you to receive information related to a specific place and time.
• Toys: LEDs are used in many toys, which can be used for inexpensive communication between interactive toys.

Prototype for developers

Li-1st allows customers to quickly develop and test Li-Fi applications. The device supports full duplex communication with a throughput of 11.5 Mbps at a distance of up to 3 m, while also providing sufficient lighting on the desktop. The working distance depends only on the strength of the light source. The device offers a simple safe wireless connection to the network, combined with LED-lamps.

Li-1st was created as a base for pilot projects of Li-Fi developers.

The first commercial product

Li-Flame was publicly demonstrated at the Mobile World Congress in Barcelona in March 2016. The device represents the next generation of the world's first high-speed wireless network based on visible light. The Li-Flame technology supports a significantly higher data density than the best Wi-Fi solutions, and its intrinsic security will eliminate unwanted external input. In addition, the combination of lighting with wireless communication significantly simplifies the infrastructure and reduces power consumption.

Li-Flame provides:

• Half-duplex communication 10 Mbit / s at a distance of up to 3 m with standard luminaires;
• Full mobility (portable desktop unit with autonomous power) with high data transfer rate due to tight installation of Li-Fi access points;
• Secure wireless communication within the premises, which eliminates the risk of signal leakage;
• Multi-user access points, providing greater bandwidth for each user;
• Secure wireless communication in environments where radio frequencies are undesirable or inaccessible;
• Flexibility in the design of communication networks;
• Expanding the range of wireless applications;
• Saving on lighting and telecommunications equipment due to the use of a single infrastructure.

Ceiling unit:

• Data and power are supplied via a standard Ethernet port.
• Easy installation.
• It is connected to the LED-light, forming attosots.
• Multiple access.
• Smooth transition between access points.

Tabletop part:

• Connect to the client device via the USB port.
• 10 Mbit / s infrared uplink to the ceiling.
• The swivel head of the transceiver can be adjusted by the user.
• Battery powered and portable.

The fastest, the smallest and the most protected

LiFi-X is the development of the Li-Flame system. It allows you to deploy a full-fledged network and, unlike existing products, supports multiple access, roaming, full mobility, and is also easy to use. From the previous version differs full duplex communication at a speed of 40 Mbit / s in both outgoing and incoming directions, and full mobility provided by portable USB-station.

Access Point LiFi-X:

• Power support via PoE or PLC.
• Easy installation.
• Connection to LED-lights for the formation of atto-cells.
• Multiple access.
• Smooth switching between access points.

Station LiFi-X:

• USB 2.0.

Literature

Books on Li-Fi technology, despite its novelty, are not uncommon, however, most of them are not translated into Russian. Here are just some of them:

• Arnon, Shlomi. Visible light communication. Cambridge, United Kingdom: Cambridge University Press, 2015. Print.
• Dimitrov, Svilen, and Harald Haas. Principles of LED light communications: towards networked Li-Fi. Cambridge: Cambridge University Press, 2015. Print.
• Ghassemlooy, Zabih, W Popoola, and S Rajbhandari. Optical wireless communications system and channel modulating with MATLAB. Boca Raton, FL: CRC Press, 2013. Print.

Books are available in the online store Amazon.