Li-Fi ( Light Fidelity ) is a bi - directional high-speed wireless communication technology. The term was coined by Harald Haas. [1] This type of data transmission uses visible light in open space without a waveguide, as a communication channel (unlike radio waves in Wi-Fi ). Thus, Li-Fi belongs to VLC technology.
Content
Technology Details
This technology uses light from light emitting diodes ( LEDs ) as a storage medium. [2] It is projected that the average annual growth rate of the Li-Fi market will be 82% between 2013 and 2018 and will be more than $ 6 billion per year by 2018. [3]
Visible light communications works by switching the voltage supply to the LEDs at a very high frequency, [4] invisible to the human eye. Light waves cannot penetrate walls, therefore the range of Li-Fi is small.
PureLiFi is an example of the first consumer-friendly Li-Fi system. She was introduced in 2014 at the Mobile World Congress in Barcelona. [five]
Bg-Fi is a Li-Fi system consisting of an application for a mobile device and a simple device, such as an IoT device, with a color sensor, a microcontroller and firmware . The light from the display of the mobile device is sent to a color sensor, which converts the light into digital information. Light emitting diodes allow synchronization with a mobile device. [6] [7]
History
Harald Haas, who teaches at the University of Edinburgh in the UK, claims to have invented Li-Fi. He is a pioneer in the use of the term Li-Fi and co-founder of pureLiFi. [eight]
On the other hand, a group of Chinese scientists [9] from Fudan University are regarded as inventors of technology.
Standards
Like Wi-Fi, Li-Fi uses protocols similar to IEEE 802.11 , but it uses electromagnetic waves of the visible light range (instead of radio waves similar to IEEE 802.3 , but without the use of optical fiber), which has a much wider bandwidth .
The IEEE 802.15.7 standard defines a physical layer (PHY) and a medium access control (MAC) layer.
The standard defines three physical (PHY) layers with different bandwidths:
- PHY I was created for external use and operates at speeds from 11.67 Kbps to 267.6 Kbps.
- PHY II allows you to achieve data transfer rates from 1.25 Mbit / s to 96 Mbit / s.
- PHY III is intended for multiple sources with a specific modulation method: Color Shift Keyring (CSK), which can be translated as “Wavelength Shift Manipulation”. PHY III can reach speeds from 12 Mbps to 96 Mbps. [ten]
Advantages and disadvantages [11]
Benefits:
- Simplicity and low cost of implementation;
- No license to use is required;
- Lack of radio frequency in technology;
- Visible light does not conflict with other electromagnetic frequencies, so Li-Fi technology can be used, for example: on board an airplane or in medical institutions.
Disadvantages:
- Mandatory line of sight between receiver and transmitter;
- With bright exposure, for example, sunlight, malfunctions and errors in operation are possible.
See also
- Bluetooth
- FSO (Free-space communication)
- IrDA
- Near Field Communication (NFC)
- Spatial light modulator
- Super wifi
Notes
- ↑ Harald Haas. Harald Haas: Wireless data from every light bulb unspecified . ted.com .
- ↑ Sherman, Joshua How LED Light Bulbs could replace Wi-Fi . Digital Trends (October 30, 2013). Date of treatment November 29, 2015.
- ↑ Global Visible Light Communication (VLC) / Li-Fi Technology Market worth $ 6,138.02 Million by 2018 . MarketsandMarkets (January 10, 2013). Date of treatment November 29, 2015.
- ↑ Coetzee, Jacques LiFi beats Wi-Fi with 1Gb wireless speeds over pulsing LEDs unspecified . Gearburn (January 13, 2013). Date of treatment November 29, 2015.
- ↑ pureLiFi to demonstrate first ever Li-Fi system at Mobile World Congress . Virtual-Strategy Magazine (February 19, 2014). Date of treatment November 29, 2015. Archived December 3, 2015.
- ↑ Giustiniano, Domenico; Tippenhauer, Nils Ole; Mangold, Stefan. Low-Complexity Visible Light Networking with LED-to-LED Communication : journal. - Zurich, Switzerland. Archived on June 20, 2015.
- ↑ Dietz, Paul; Yerazunis, William; Leigh, Darren. Very Low-Cost Sensing and Communication Using Bidirectional LEDs ( journal ) : journal. - 2003. - July.
- ↑ The Future's Bright - The Future's Li-Fi . The Caledonian Mercury (November 29, 2013). Date of treatment November 29, 2015. Archived November 4, 2015.
- ↑ China achieves wireless Internet access via lightbulbs | Zdnet
- ↑ An IEEE Standard for Visible Light Communications visiblelightcomm.com, dated April 2011.
- ↑ What is Li-Fi and can it replace Wi-Fi? (Russian) , KV.by (June 10, 2016). Archived January 13, 2018. Date of treatment January 13, 2018.