Wi-Fi

Wi-Fi (Wi-Fi is an abbreviation of the phrase Wireless Fidelity.) is a type of radio technologies that is commonly used for the wireless local area networking (WLAN) of devices which is based around the IEEE 802.11 family of standards. Wi‑Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that successfully complete interoperability certification testing. Wi-Fi uses multiple parts of the IEEE 802 protocol family and is designed to seamlessly interwork with its wired sister protocol Ethernet. Wi-Fi networks have no physical wired connection between sender and receiver by using radio frequency (RF) technology — a frequency within the electromagnetic spectrum associated with radio wave propagation. When an RF current is supplied to an antenna, an electromagnetic field is created that then is able to propagate through space.

History

In 1971, ALOHAnet connected the Great Hawaiian Islands with a UHF wireless packet network. ALOHAnet and the ALOHA protocol were early forerunners to Ethernet, and later the IEEE 802.11 protocols, respectively.

A 1985 ruling by the U.S. Federal Communications Commission released the ISM band for unlicensed use. These frequency bands are the same ones used by equipment such as microwave ovens and are subject to interference.

Advantages

• Convenient
  • Useful for smartphones, tablet devices and other portable devices to connect at any convenient location within premises.
• Simplicity
  • To connect a new device with a network, simply turn on the Wi-Fi and do the simple configuration settings.
• Mobility
  • Internet can be accessed from anywhere, ie. Bus, train, coffee-shop, super market, etc.
• Expandability
  • It is convenient to add more wireless devices with current hardware settings without any cost and time.
• Efficiency
  • WiFi enabled devices are used at offices for convenient to access their files at any location and it gives more productivity for the company.
• Cost Control
  • In WiFi network devices can be added without any cost unlike cables needs to be get man power to do the job.
• Standardization of Technology
  • Wi-Fi technology has standardized for all countries, it helps for the mobile devices to connect the WiFi regardless of the location

LiFi

Li-Fi (short for light fidelity) is wireless communication technology, which utilizes light to transmit data and position between devices. The term was first introduced by Harald Haas during a 2011 TEDGlobal talk show in Edinburgh. LiFi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission.  Li-Fi is a light communication system that is capable of transmitting data at high speeds over the visible light, ultraviolet, and infrared spectrums. In its present state, only LED lamps can be used for the transmission of visible light.

In terms of its end use, the technology is similar to Wi-Fi – the key technical difference being that Wi-Fi uses radio frequency. to transmit data. Using light to transmit data allows Li-Fi to offer several advantages, most notably a wider bandwidth.

Li-Fi is a derivative of optical wireless communications (OWC) technology, which uses light from light-emitting diodes (LEDs) as a medium to deliver networked, mobile, high-speed communication in a similar manner to Wi-Fi. The Li-Fi market was projected to have a compound annual growth rate of 82% from 2013 to 2018 and to be worth over $6 billion per year by 2018.  However, the market has not developed as such and Li-Fi remains with a niche market, mainly for technology evaluation.

Visible light communications (VLC) works by switching the current to the LEDs off and on at a very high speed.

Benefits of LiFi:

• 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 piggybacking.
• 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.

History

Professor Harald Haas coined the term “Li-Fi” at his 2011 TED Global Talk where he introduced the idea of “wireless data from every light”.He is a Chair Professor of Mobile Communications at the University of Edinburgh, and the co-founder of pureLiFi along with Dr Mostafa Afgani. Haas promoted this technology in his 2011 TED Global talk and helped start a company to market it. PureLiFi, formerly pureVLC, is an original equipment manufacturer (OEM) firm set up to commercialize Li-Fi products for integration with existing LED-lighting systems. Oledcomm, French company founded by Pr Suat Topsu from Paris-Saclay University.

The IEEE 802.15.7 standard defines the physical layer (PHY) and media access control (MAC) layer. The standard is able to deliver enough data rates to transmit audio, video and multimedia services. It takes into account optical transmission mobility, its compatibility with artificial lighting present in infrastructures, and the interference which may be generated by ambient lighting.

The standard defines three PHY layers with different rates:

• The PHY 1 was established for outdoor application and works from 11.67 kbit/s to 267.6 kbit/s.
• The PHY 2 layer permits reaching data rates from 1.25 Mbit/s to 96 Mbit/s.
• The PHY 3 is used for many emissions sources with a particular modulation method called color shift keying (CSK).

http://ciscorouterswitch.over-blog.com