Wi-Fi


Wi-Fi (pronounced /ˈwaɪfaɪ/) is a trademark of the Wi-Fi Alliance that may be used with certified products that belong to a class of wireless local area network (WLAN) devices based on the IEEE 802.11 standards. Because of the close relationship with its underlying standard, the term Wi-Fi is often used as a synonym for IEEE 802.11 technology.[1][2]

The Wi-Fi Alliance is a global, non-profit association of companies that promotes WLAN technology and certifies products if they conform to certain standards of interoperability. Not every IEEE 802.11-compliant device is submitted for certification to the Wi-Fi Alliance, sometimes because of costs associated with the certification process and the lack of the Wi-Fi logo does not imply a device is incompatible with Wi-Fi devices.

Today, an IEEE 802.11 device is installed in many personal computers, video game consoles, smartphones, printers, and other peripherals, and virtually all laptop or palm-sized computers.

Internet access

A roof mounted Wi-Fi antenna

A Wi – Fi enabled device such as a personal computer, video game console, mobile phone, MP3 player or personal digital assistant can connect to the Internet when within range of a wireless network connected to the Internet. The coverage of one or more interconnected access points — called a hotspot — can comprise an area as small as a few rooms or as large as many square miles covered by a group of access points with overlapping coverage. Wi-Fi technology has been used in wireless mesh networks, for example, in London.[3]

In addition to private use in homes and offices, Wi-Fi can provide public access at Wi-Fi hotspots provided either free of charge or to subscribers to various commercial services. Organizations and businesses such as airports, hotels and restaurants often provide free hotspots to attract or assist clients. Enthusiasts or authorities who wish to provide services or even to promote business in selected areas sometimes provide free Wi-Fi access. As of 2008[update] there are more than 300 metropolitan-wide Wi-Fi (Muni-Fi) projects in progress.[4] There were 879 Wi-Fi based Wireless Internet service providers in the Czech Republic as of May 2008.[5][6]

Routers which incorporate a digital subscriber line modem or a cable modem and a Wi-Fi access point, often set up in homes and other premises, provide Internet-access and internetworking to all devices connected (wirelessly or by cable) to them. One can also connect Wi-Fi devices in ad hoc mode for client-to-client connections without a router. Wi-Fi also enables places which would traditionally not have network to be connected, for example bathrooms, kitchens and garden sheds.

History

Wi-Fi uses both single-carrier direct-sequence spread spectrum radio technology (part of the larger family of spread spectrum systems) and multi-carrier orthogonal frequency-division multiplexing (OFDM) radio technology. The deregulation of certain radio-frequencies for unlicensed spread spectrum deployment enabled the development of Wi-Fi products, its onetime competitor HomeRF, Bluetooth, and many other products such as some types of cordless telephones.

Unlicensed spread spectrum was first made available in the US by the FCC in rules adopted on May 9, 1985[12] and these FCC regulations were later copied with some changes in many other countries enabling use of this technology in all major countries. The FCC action was proposed by Michael Marcus of the FCC staff in 1980 and the subsequent regulatory action took 5 more years. It was part of a broader proposal to allow civil use of spread spectrum technology and was opposed at the time by mainstream equipment manufacturers and many radio system operators.[13]
Half-size ISA 2.4 GHz WaveLAN card by AT&T

The precursor to Wi-Fi was invented in 1991 by NCR Corporation/AT&T (later Lucent Technologies & Agere Systems) in Nieuwegein, the Netherlands. It was initially intended for cashier systems; the first wireless products were brought on the market under the name WaveLAN with speeds of 1 Mbit/s to 2 Mbit/s. Vic Hayes, who held the chair of IEEE 802.11 for 10 years and has been named the “father of Wi-Fi,” was involved in designing standards such as IEEE 802.11b, and 802.11a.

Key portions of the IEEE 802.11 technology underlying Wi-Fi (in its a, g, and n varieties) were determined to be infringing on U.S. Patent 5,487,069, which was filed in 1993[14] by CSIRO, an Australian research body. The patent has been the subject of protracted and ongoing legal battles between CSIRO and major IT corporations. In 2009, the CSIRO settled with 14 companies, including Hewlett-Packard, Intel, Dell, Toshiba, ASUS, Microsoft and Nintendo, under confidential terms. The revenue arising from these settlements to October 2009 is approximately AU$200 million. [15][16][17][18][19][20]

Europe leads overall in uptake of wireless-phone technology but the US leads in Wi-Fi systems partly because they lead in laptop usage. As of July 2005, there were at least 68,643 Wi-Fi locations worldwide, a majority in the US, then the UK and Germany. The US and Western Europe make up about 80% of the worldwide Wi-Fi users. Plans are underway in areas of the US to provide public Wi-Fi coverage as a public free service. Even with these large numbers and more expansion, the extent of actual Wi-Fi usage is lower than expected. Jupiter Research found that only 15% of people have used Wi-Fi and only 6% in a public place.[21]

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