Wi-Fi

The Wi-Fi logo used by the Wi-Fi Alliance.

Wi-Fi (pron.: /ˈwf/, also spelled Wifi or WiFi) is a popular technology that allows an electronic device to exchange data wirelessly (using radio waves) over a computer network, including high-speed Internet connections. The Wi-Fi Alliance defines Wi-Fi as any “wireless local area network (WLAN) products that are based on the Institute of Electrical and Electronics Engineers‘ (IEEE) 802.11 standards”.[1] However, since most modern WLANs are based on these standards, the term “Wi-Fi” is used in general English as a synonym for “WLAN”.

A device that can use Wi-Fi (such as a personal computer, video-game console, hotspot) has a range of about 20 meters (65 feet) indoors and a greater range outdoors. Hotspot coverage can comprise an area as small as a single room with walls that block radio waves or as large as many square miles — this is achieved by using multiple overlapping access points.

“Wi-Fi” is a trademark of the Wi-Fi Alliance and the brand name for products using the interoperability certification testing successfully may use the “Wi-Fi CERTIFIED” designation and trademark.

Wi-Fi has had a checkered security history. Its earliest encryption system, Wired Equivalent Privacy (WEP), proved easy to break. Much higher quality protocols, WPA and WPA2, were added later. However, an optional feature added in 2007, called Wi-Fi Protected Setup (WPS), has a flaw that allows a remote attacker to recover the router’s WPA or WPA2 password in a few hours on most implementations.[2] Some manufacturers have recommended turning off the WPS feature. The Wi-Fi Alliance has since updated its test plan and certification program to ensure all newly certified devices resist brute-force AP PIN attacks.

Contents

[edit] History

802.11 technology has its origins in a 1985 ruling by the US Federal Communications Commission that released the ISM band for unlicensed use.[3] In 1991, NCR Corporation with AT&T Corporation invented the precursor to 802.11 intended for use in cashier systems. The first wireless products were under the name WaveLAN.

[5]

A large number of patents by many companies are used in 802.11 standard.[13]

In 1999, the Wi-Fi Alliance was formed as a trade association to hold the Wi-Fi trademark under which most products are sold.[14]

The key technologies behind Wi-Fi were developed by the radioastronomer John O’Sullivan as a by-product in a research project, “a failed experiment to detect exploding mini black holes the size of an atomic particle”.[15]

[edit] The name

The term Wi-Fi, first used commercially in August 1999,Hi-Fi (high fidelity), and also created the Wi-Fi logo.

The Wi-Fi Alliance initially used an [21] There was no official statement related to the dropping of the term.

The yin-yang Wi-Fi logo indicates the certification of a product for interoperability.[20]

Non-Wi-Fi technologies intended for fixed points such as 4G.

[edit] Wi-Fi certification

The IEEE does not test equipment for compliance with their standards. The wide area network (WAN) connections. Manufacturers with membership in the Wi-Fi Alliance, whose products pass the certification process, gain the right to mark those products with the Wi-Fi logo.

Specifically, the certification process requires conformance to the IEEE 802.11 radio standards, the WPA and WPA2 security standards, and the EAP authentication standard. Certification may optionally include tests of IEEE 802.11 draft standards, interaction with cellular-phone technology in converged devices, and features relating to security set-up, multimedia, and power-saving.[24]

Not every Wi-Fi device is submitted for certification. The lack of Wi-Fi certification does not necessarily imply that a device is incompatible with other Wi-Fi devices. If it is compliant or partly compatible, the Wi-Fi Alliance may not object to its description as a Wi-Fi device[Federal Communications Commission (FCC) to describe proposed networking in the UHF TV band in the US, may or may not be sanctioned.

[edit] Uses

A sticker indicating to the public that a location is within range of a Wi-Fi network. A dot with curved lines radiating from it is a common symbol for Wi-Fi, representing a point transmitting a signal.[25]

To connect to a Wi-Fi LAN, a computer has to be equipped with a Ethernet frames“. Each station is constantly tuned in on the radio frequency communication channel to pick up available transmissions.

[edit] Internet access

A Wi-Fi-enabled device can connect to the Internet when within range of a wireless mesh networks in London, UK.

Wi-Fi provides service in private homes, high street chains and independent businesses, as well as in public spaces at Wi-Fi hotspots set up either free-of-charge or commercially. Organizations and businesses, such as airports, hotels, and restaurants, often provide free-use hotspots to attract customers. Enthusiasts or authorities who wish to provide services or even to promote business in selected areas sometimes provide free Wi-Fi access.

internetworking to all devices connected to them, wirelessly or via cable.

Similarly, there are battery-powered routers that include a cellular mobile Internet radiomodem and Wi-Fi access point. When subscribed to a cellular phone carrier, they allow nearby Wi-FI stations to access the Internet over 2G, 3G, or 4G networks. Many smartphones have a built-in capability of this sort, including those based on Android, Bada, iOS (iPhone), and Symbian, though carriers often disable the feature, or charge a separate fee to enable it, especially for customers with unlimited data plans.[26] “Internet pucks” provide standalone facilities of this type as well, without use of a smartphone; examples include the MiFi– and WiBro-branded devices. Some laptops that have a cellular modem card can also act as mobile Internet Wi-Fi access points.

Wi-Fi also connects places that normally don’t have network access, such as kitchens and garden sheds.

[edit] City-wide Wi-Fi

An outdoor Wi-Fi access point

In the early 2000s, many cities around the world announced plans to construct city-wide Wi-Fi networks. There are many successful examples; in 2004, Mysore became India’s first Wi-fi-enabled city and second in the world after Jerusalem. A company called WiFiyNet has set up hotspots in Mysore, covering the complete city and a few nearby villages.[27]

In 2005, [29]

In May 2010, [32] already have extensive outdoor Wi-Fi coverage.

Officials in South Korea’s capital are moving to provide free Internet access at more than 10,000 locations around the city, including outdoor public spaces, major streets and densely populated residential areas. Seoul will grant leases to KT, LG Telecom and SK Telecom. The companies will invest $44 million in the project, which will be completed in 2015.[33]

[edit] Campus-wide Wi-Fi

Many traditional college campuses in the United States provide at least partial wireless Wi-Fi Internet coverage. eduroam international authentication infrastructure.

In 2000, Drexel University in Philadelphia became the United States’s first major university to offer completely wireless Internet access across its entire campus.[37]

The Philippines to implement a campus-wide Wi-Fi coverage for its students, faculty, and staff. St Xavier’s College in Calcutta, India has recently implemented Wi-Fi coverage at its campus.

[edit] Direct computer-to-computer communications

Wi-Fi also allows communications directly from one computer to another without an access point intermediary. This is called ad hoc Wi-Fi transmission. This wireless ad hoc network mode has proven popular with multiplayer handheld game consoles, such as the Nintendo DS, PlayStation Portable, digital cameras, and other consumer electronics devices. Some devices can also share their Internet connection using ad-hoc, becoming hotspots or “virtual routers”.[38]

Similarly, the Wi-Fi Alliance promotes a specification called [40]

[edit] Advantages and limitations

A keychain-size Wi-Fi detector

[edit] Advantages

Wi-Fi allows cheaper deployment of local area networks (LANs). Also spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.

Manufacturers are building wireless network adapters into most laptops. The price of citation needed]

Different competitive brands of access points and client network-interfaces can inter-operate at a basic level of service. Products designated as “Wi-Fi Certified” by the Wi-Fi Alliance are mobile phones, any standard Wi-Fi device will work anywhere in the world.

WMM) make Wi-Fi more suitable for latency-sensitive applications (such as voice and video). Power saving mechanisms (WMM Power Save) extend battery life.

[edit] Limitations

Spectrum assignments and operational limitations are not consistent worldwide: most of Europe allows for an additional two channels beyond those permitted in the US for the 2.4 GHz band (1–13 vs. 1–11), while Japan has one more on top of that (1–14). As of 2007, Europe is essentially homogeneous in this respect.

A Wi-Fi signal occupies five channels in the 2.4 GHz band. Any two channels numbers that differ by five or more, such as 2 and 7, do not overlap. The oft-repeated adage that channels 1, 6, and 11 are the only non-overlapping channels is, therefore, not accurate. Channels 1, 6, and 11 are the only group of three non-overlapping channels in the U.S. In Europe and Japan using Channels 1, 5, 9, and 13 for 802.11g and n is recommended.[citation needed]

dBm (100 mW).

The current ‘fastest’ norm, 802.11n, uses double the radio spectrum/bandwidth (40 MHz) compared to 802.11a or 802.11g (20 MHz). This means there can be only one 802.11n network on the 2.4 GHz band at a given location, without interference to/from other WLAN traffic. 802.11n can also be set to use 20 MHz bandwidth only to prevent interference in dense community.

[edit] Range

Wi-Fi networks have limited range. A typical wireless access point using FCC Part 15 in the US.

Due to reach requirements for wireless LAN applications, Wi-Fi has fairly high power consumption compared to some other standards. Technologies such as Bluetooth (designed to support wireless PAN applications) provide a much shorter propagation range of <10m[42] and so in general have a lower power consumption. Other low-power technologies such as ZigBee have fairly long range, but much lower data rate. The high power consumption of Wi-Fi makes battery life in mobile devices a concern.

Researchers have developed a number of “no new wires” technologies to provide alternatives to Wi-Fi for applications in which Wi-Fi’s indoor range is not adequate and where installing new wires (such as IPTV distribution) where indoor range is more important than mobility.

Due to the complex nature of radio propagation at typical Wi-Fi frequencies, particularly the effects of signal reflection off trees and buildings, algorithms can only approximately predict Wi-Fi signal strength for any given area in relation to a transmitter.[43] This effect does not apply equally to long-range Wi-Fi, since longer links typically operate from towers that transmit above the surrounding foliage.

The practical range of Wi-Fi essentially confines mobile use to such applications as inventory-taking machines in warehouses or in retail spaces, barcode-reading devices at check-out stands, or receiving/shipping stations. Mobile use of Wi-Fi over wider ranges is limited, for instance, to uses such as in an automobile moving from one hotspot to another. Other wireless technologies are more suitable for communicating with moving vehicles.

[edit] Data security risks

The most common wireless encryption-standard, Wired Equivalent Privacy (WEP), has been shown to be easily breakable even when correctly configured. Wi-Fi Protected Access (WPA and WPA2) encryption, which became available in devices in 2003, aimed to solve this problem. Wi-Fi access points typically default to an encryption-free (open) mode. Novice users benefit from a zero-configuration device that works out-of-the-box, but this default does not enable any wireless security, providing open wireless access to a LAN. To turn security on requires the user to configure the device, usually via a software graphical user interface (GUI). On unencrypted Wi-Fi networks connecting devices can monitor and record data (including personal information). Such networks can only be secured by using other means of protection, such as a VPN or secure Hypertext Transfer Protocol (HTTPS) over Transport Layer Security.

[edit] Interference

Wi-Fi connections can be disrupted or the internet speed lowered by having other devices in the same area. Many 2.4 GHz 802.11b and 802.11g access-points default to the same channel on initial startup, contributing to congestion on certain channels. Wi-Fi pollution, or an excessive number of access points in the area, especially on the neighboring channel, can prevent access and interfere with other devices’ use of other access points, caused by overlapping channels in the 802.11g/b spectrum, as well as with decreased signal-to-noise ratio (SNR) between access points. This can become a problem in high-density areas, such as large apartment complexes or office buildings with many Wi-Fi access points.

Additionally, other devices use the 2.4 GHz band: microwave ovens, ISM band devices, security cameras, ZigBee devices, Bluetooth devices, video senders, cordless phones, baby monitors, and (in some countries) Amateur radio all of which can cause significant additional interference. It is also an issue when municipalities[44] or other large entities (such as universities) seek to provide large area coverage.

[edit] Hardware

[edit] Standard devices

OSBRiDGE 3GN – UMTS/GSM Gateway in one device

An Bluetooth on a Sony Vaio E series laptop

USB wireless adapter

A data between connected wireless devices in addition to a (usually) single connected wired device, most often an ethernet hub or switch, allowing wireless devices to communicate with other wired devices.

Wireless adapters allow devices to connect to a wireless network. These adapters connect to devices using various external or internal interconnects such as PCI, miniPCI, USB, ExpressCard, Cardbus and PC Card. As of 2010, most newer laptop computers come equipped with built in internal adapters.

Wireless routers integrate a Wireless Access Point, ethernet switch, and internal router firmware application that provides IP routing, NAT, and DNS forwarding through an integrated WAN-interface. A wireless router allows wired and wireless ethernet LAN devices to connect to a (usually) single WAN device such as a cable modem or a DSL modem. A wireless router allows all three devices, mainly the access point and router, to be configured through one central utility. This utility is usually an integrated web server that is accessible to wired and wireless LAN clients and often optionally to WAN clients. This utility may also be an application that is run on a desktop computer, as is the case with as Apple’s AirPort, which is managed with the AirPort Utility on Mac OS X and Microsoft Windows.[45]

Wireless network bridges connect a wired network to a wireless network. A bridge differs from an access point: an access point connects wireless devices to a wired network at the data-link layer. Two wireless bridges may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes.

Wireless range-extenders or wireless repeaters can extend the range of an existing wireless network. Strategically placed range-extenders can elongate a signal area or allow for the signal area to reach around barriers such as those pertaining in L-shaped corridors. Wireless devices connected through repeaters will suffer from an increased latency for each hop, as well as from a reduction in the maximum data throughput that is available. In addition, the effect of additional users using a network employing wireless range-extenders is to consume the available bandwidth faster than would be the case where but a single user migrates around a network employing extenders. For this reason, wireless range-extenders work best in networks supporting very low traffic throughput requirements, such as for cases where but a single user with a Wi-Fi equipped tablet migrates around the combined extended and non-extended portions of the total connected network. Additionally, a wireless device connected to any of the repeaters in the chain will have a data throughput that is also limited by the “weakest link” existing in the chain between where the connection originates and where the connection ends. Networks employing wireless extenders are also more prone to degradation from interference from neighboring access points that border portions of the extended network and that happen to occupy the same channel as the extended network.

The security standard, Wi-Fi Protected Setup, allows embedded devices with limited graphical user interface to connect to the Internet with ease. Wi-Fi Protected Setup has 2 configurations: The Push Button configuration and the PIN configuration. These embedded devices are also called The Internet of Things and are low-power, battery-operated embedded systems. A number of Wi-Fi manufacturers design chips and modules for embedded Wi-Fi, such as GainSpan.[46]

[edit] Distance records

Distance records (using non-standard devices) include 382 km (237 mi) in June 2007, held by Ermanno Pietrosemoli and EsLaRed of Venezuela, transferring about 3 MB of data between the mountain-tops of [49]

[edit] Embedded systems

Embedded serial-to-Wi-Fi module

Increasingly in the last few years (particularly as of 2007), embedded Wi-Fi modules have become available that incorporate a real-time operating system and provide a simple means of wirelessly enabling any device which has and communicates via a serial port.[51]

These Wi-Fi modules are designed by OEMs so that implementers need only minimal Wi-Fi knowledge to provide Wi-Fi connectivity for their products.

[edit] Multiple access points

Increasing the number of Wi-Fi access points provides network redundancy, support for fast mesh topologies.

[edit] Network security

The main issue with wireless network security is its simplified access to the network compared to traditional wired networks such as ethernet, with wired networking one must either gain access to a building (physically connecting into the internal network) or break through an external firewall. To enable Wi-Fi, one merely needs to be within the wireless range of the Wi-Fi network. Most business networks protect sensitive data and systems by attempting to disallow external access. Enabling wireless connectivity reduces security if the network uses inadequate or no encryption.[52]

An attacker who has gained access to a Wi-Fi network router can initiate a DNS spoofing attack against any other user of the network by forging a response before the queried DNS server has a chance to reply.[53]

[edit] Securing methods

A common measure to deter unauthorized users involves hiding the access point’s name by disabling the SSID broadcast. While effective against the casual user, it is ineffective as a security method because the SSID is broadcast in the clear in response to a client SSID query. Another method is to only allow computers with known MAC addresses to join the network,[54] but determined eavesdroppers may be able join the network by spoofing an authorized address.

Wired Equivalent Privacy (WEP) encryption was designed to protect against casual snooping but it is no longer considered secure. Tools such as AirSnort or Aircrack-ng can quickly recover WEP encryption keys.[55] Because of WEP’s weakness the Wi-Fi Alliance approved Wi-Fi Protected Access (WPA) which uses TKIP. WPA was specifically designed to work with older equipment usually through a firmware upgrade. Though more secure than WEP, WPA has known vulnerabilities.

The more secure WPA2 using Advanced Encryption Standard was introduced in 2004 and is supported by most new Wi-Fi devices. WPA2 is fully compatible with WPA.[56]

A flaw in a feature added to Wi-Fi in 2007, called Wi-Fi Protected Setup, allows WPA and WPA2 security to be bypassed and effectively broken in many situations. The only remedy as of late 2011 is to turn off Wi-Fi Protected Setup,[57] which is not always possible.

[edit] Piggybacking

Piggybacking refers to access to a wireless Internet connection by bringing one’s own computer within the range of another’s wireless connection, and using that service without the subscriber’s explicit permission or knowledge.

During the early popular adoption of 802.11, providing open access points for anyone within range to use was encouraged[by whom?] to cultivate wireless community networks,[58] particularly since people on average use only a fraction of their downstream bandwidth at any given time.

Recreational logging and mapping of other people’s access points has become known as wardriving. Indeed, many access points are intentionally installed without security turned on so that they can be used as a free service. Providing access to one’s Internet connection in this fashion may breach the Terms of Service or contract with the ISP. These activities do not result in sanctions in most jurisdictions; however, legislation and case law differ considerably across the world. A proposal to leave graffiti describing available services was called warchalking.[59] A Florida court case determined that owner laziness was not to be a valid excuse.[citation needed]

Piggybacking often occurs unintentionally, since most access points are configured without encryption by default[HTTP.

[edit] Safety

The [61]

A small percentage of Wi-Fi users have reported adverse health issues after repeat exposure and use of Wi-Fi,[63]

One study claims, in preliminary results, that “laptops (Wi-Fi mode) on the lap near the testicles may result in decreased male fertility”.[65]

[edit] See also

[edit] Notes

[edit] References

  1. ^ What is Wi-Fi? – A Word Definition From the Webopedia Computer Dictionary
  2. ^ http://sviehb.files.wordpress.com/2011/12/viehboeck_wps.pdf
  3. ^ “Wi-Fi (wireless networking technology)”. Encyclopædia Britannica. http://www.britannica.com/EBchecked/topic/1473553/Wi-Fi. Retrieved 2010-02-03.
  4. ^ Ben Charny (December 6, 2002). “CNET Vision series”. CNET. http://news.cnet.com/1200-1070-975460.html. Retrieved 2011-10-14.
  5. ^ Olga Kharif (April 1, 2003). “Paving the Airwaves for Wi-Fi”. Bloomberg Businessweek. http://www.businessweek.com/stories/2003-03-31/paving-the-airwaves-for-wi-fi. Retrieved 2011-10-14.
  6. ^ IEEE-SA – IEEE 802.11 and Amendments Patent Letters of Assurance
  7. ^ Sygall, David (December 7, 2009). “How Australia’s top scientist earned millions from Wi-Fi”. The Sydney Morning Herald. http://www.smh.com.au/technology/sci-tech/how-australias-top-scientist-earned-millions-from-wifi-20091207-kep4.html.
  8. ^ http://www.theage.com.au/technology/enterprise/csiro-to-reap-lazy-billion-from-worlds-biggest-tech-companies-20100601-wsu2.html. Retrieved 8 June 2010.
  9. ^ World changing Aussie inventions – Australian Geographic
  10. ^ How the Aussie government “invented WiFi” and sued its way to $430 million | Ars Technica
  11. ^ “Australia’s Biggest Patent Troll Goes After AT&T, Verizon and T-Mobile”. CBS News. http://www.cbsnews.com/8301-505124_162-43340647/australias-biggest-patent-troll-goes-after-at038t-verizon-and-t-mobile/.
  12. ^ Australian scientists cash in on Wi-Fi invention: SMH 1 April 2012
  13. ^ CSIRO wins legal battle over Wi-Fi patent: ABC 1 April 2012
  14. ^ “Wi-Fi Alliance: Organization”. Official industry association web site. http://www.wi-fi.org/organization.php. Retrieved August 23, 2011.
  15. ^ Phil Mercer (August 11,2012). “Wi-fi, dual-flush loos and eight more Australian inventions”. http://www.bbc.co.uk/news/magazine-20071644.
  16. ^ US Patent and Trademark Office.[verification needed]
  17. ^ http://boingboing.net/2005/11/08/wifi-isnt-short-for.html. Retrieved 2012-12-21.
  18. ^ “Wireless Fidelity’ Debunked”. Wi-Fi Planet. 2007-04-27. http://www.wi-fiplanet.com/columns/article.php/3674591. Retrieved 2007-08-31.
  19. ^ “What is the True Meaning of Wi-Fi?”. Teleclick. http://www.teleclick.ca/2005/12/what-is-the-true-meaning-of-wi-fi/. Retrieved 2007-08-31.
  20. ^ http://www.wi-fi.org/files/wp_4_Securing%20Wireless%20Networks_2-6-03.pdf. Retrieved 2009-11-30.
  21. ^ “WPA Deployment Guidelines for Public Access Wi-Fi Networks”. Wi-Fi Alliance. 2004-10-28. http://www.wi-fi.org/files/wp_6_WPA%20Deployment%20for%20Public%20Access_10-28-04.pdf. Retrieved 2009-11-30.
  22. ^ The Wi-Fi Alliance also developed technology that expanded the applicability of Wi-Fi, including a simple set up protocol (Wi-Fi Protected Set Up) and a peer to peer connectivity technology (Wi-Fi Peer to Peer) “Wi-Fi Alliance: Organization”. www.wi-fi.org. http://www.wi-fi.org/organization.php. Retrieved 2009-10-22.
  23. ^ “Wi-Fi Alliance: White Papers”. www.wi-fi.org. http://www.wi-fi.org/wp/wifi-alliance-certification/. Retrieved 2009-10-22.
  24. ^ “Wi-Fi Alliance: Programs”. www.wi-fi.org. http://www.wi-fi.org/certification_programs.php. Retrieved 2009-10-22.
  25. http://books.google.com/books?id=6tLAyQLSzG0C. Retrieved 11 November 2012.
  26. ^ “Mifi vs Joikuspot”. mificlub.com. Archived from the original on May 15, 2011. http://web.archive.org/web/20110515192059/http://www.mificlub.com/2010/07/mifi-vs-joikuspot/.
  27. ^ The Telegraph – Say hello to India’s first wirefree city
  28. dead link]
  29. ^ Alexander, Steve; Brandt, Steve (December 5, 2010). “Minneapolis moves ahead with wireless”. The Star Tribune. http://www.startribune.com/business/111286134.html. Retrieved December 5, 2010.
  30. ^ “London-wide wi-fi by 2012 pledge”. BBC News. 2010-05-19. http://news.bbc.co.uk/2/hi/uk_news/england/london/8692103.stm. Retrieved 2010-05-19.
  31. ^ “City of London Fires Up Europe’s Most Advanced Wi-Fi Network”. www.govtech.com. http://www.govtech.com/dc/118717. Retrieved 2007-05-14.
  32. ^ “London gets a mile of free Wi-Fi”. .zdnet.co.uk. http://www.zdnet.co.uk/news/networking/2005/04/18/london-gets-a-mile-of-free-wi-fi-39195421/. Retrieved 200-04-18.
  33. ^ “Seoul Moves to Provide Free City-Wide WiFi Service”. VOANEWS.COM. http://blogs.voanews.com/breaking-news/2011/06/15/seoul-moves-to-provide-free-city-wide-wifi-service/. Retrieved 1 April 2012.
  34. ^ Deb Smit (October 5, 2011). “How Wi-Fi got its start on the campus of CMU, a true story”. Pop City Media. http://popcitymedia.com/innovationnews/wifi100511.aspx. Retrieved October 6, 2011.
  35. ^ “Wireless Andrew: Creating the World’s First Wireless Campus”. Carnegie Mellon University. 2007. http://www.cmu.edu/corporate/news/2007/features/wireless_andrew.shtml. Retrieved October 6, 2011.
  36. http://books.google.com/books?id=-OMoL5Irm08C&pg=PA121. Retrieved October 6, 2011.
  37. ^ “Drexel University’s Wireless Networks”. Drexel.edu. http://www.drexel.edu/irt/networks/wireless/. Retrieved 2011-10-14.
  38. ^ “Wireless Home Networking with Virtual WiFi Hotspot”. Techsansar.com. 2011-01-24. http://techsansar.com/internetworking/wireless-home-networking-virtual-wifi-hotspot-2946/. Retrieved 2011-10-14.
  39. ^ “Wi-Fi Direct allows device-to-device links”. http://www.networkworld.com/news/2009/101409-wi-fi-direct.html?hpg1=bn.
  40. ^ “Wi-Fi gets personal: Groundbreaking Wi-Fi Direct launches today”. WiFi Alliance. 2010-10-25. http://www.wi-fi.org/news_articles.php?f=media_news&news_id=1011. Retrieved 2011-01-15.
  41. ^ “802.11n Delivers Better Range”. Wi-Fi Planet. 2007-05-31. http://www.wi-fiplanet.com/tutorials/article.php/3680781.
  42. ^ IEEE Standard 802.15.4 section 1.2 (scope)
  43. ^ “WiFi Mapping Software: Footprint”. Alyrica Networks, Inc.. http://www.alyrica.net/node/20. Retrieved 2008-04-27.
  44. ^ Wilson, Tracy V.. “How Municipal WiFi Works”. computer.howstuffworks.com. http://computer.howstuffworks.com/municipal-wifi.htm. Retrieved 2008-03-12.
  45. ^ “Apple.com Airport Utility Product Page”. Apple, Inc.. http://www.apple.com/airportextreme/features/utility.html. Retrieved 2011-06-14.
  46. ^ GainSpan specifically designs for Wi-Fi technology between Wi-Fi devices. Extremely useful. “GainSpan low-power, embedded Wi-Fi”. www.gainspan.com. http://www.gainspan.com/technology/technology_overview.php. Retrieved 2010.
  47. ^ “Ermanno Pietrosemoli has set a new record for the longest communication Wi-Fi link”. http://interred.wordpress.com/2007/06/18/ermanno-pietrosemoli-has-set-a-new-record-for-the-longest-communication-wi-fi-link/. Retrieved 2008-03-10.
  48. ^ “Wireless technology is irreplaceable for providing access in remote and scarcely populated regions”. http://www.apc.org/en/news/strategic/world/wireless-technology-irreplaceable-providing-access. Retrieved 2008-03-10.
  49. ^ “Long Distance WiFi Trial” (PDF). http://www.eslared.org.ve/articulos/Long%20Distance%20WiFi%20Trial.pdf. Retrieved 2008-03-10.
  50. ^ “Quatech Rolls Out Airborne Embedded 802.11 Radio for M2M Market”. http://edageek.com/2008/04/18/embedded-wifi-radio/. Retrieved 2008-04-29.
  51. dead link]
  52. ^ “802.11 X Wireless Network in a Business Environment — Pros and Cons.”. NetworkBits.net. http://networkbits.net/wireless-printing/80211-g-pros-cons-of-a-wireless-network-in-a-business-environment/. Retrieved 2008-04-08.
  53. ^ Bernstein, Daniel J. (2002). “DNS forgery”. http://cr.yp.to/djbdns/forgery.html. Retrieved 2010-03-24. “An attacker with access to your network can easily forge responses to your computer’s DNS requests.”
  54. http://www.cs.wright.edu/~pmateti/InternetSecurity/Lectures/WirelessHacks/Mateti-WirelessHacks.htm#_Toc77524658. Retrieved 2010-02-28.
  55. ^ “Wireless Vulnerabilities & Exploits”. wirelessve.org. http://www.wirelessve.org/entries/show/WVE-2005-0020. Retrieved 2008-04-15.
  56. ^ “WPA2 Security Now Mandatory for Wi-Fi CERTIFIED Products” “WPA2 Security Now Mandatory for Wi-Fi CERTIFIED Products”. Wi-Fi Alliance. http://www.wi-fi.org/pressroom_overview.php?newsid=16.
  57. ^ http://www.kb.cert.org/vuls/id/723755 US CERT Vulnerability Note VU#723755
  58. ^ “NoCat’s goal is to bring you Infinite Bandwidth Everywhere for Free”. Nocat.net. http://nocat.net/. Retrieved 2011-10-14.
  59. ^ “Let’s Warchalk” (PDF). Matt Jones. http://www.blackbeltjones.com/warchalking/warchalking0_9.pdf. Retrieved 2008-10-09.
  60. ^ “Q&A: Wi-fi health concerns”. BBC News. 2007-05-21. http://news.bbc.co.uk/2/hi/technology/6677051.stm. Retrieved 2011-10-14.
  61. ^ “Electromagnetic Hypersensitivity (EMS)”, 2011
  62. ^ “Official website”. Globalnews.ca. http://www.globalnews.ca/programs/16×9/video.html?releasePID=ZDqUIbEn5ki6ptoRe__s2Oz5ODXbDiZ6. Retrieved 2011-10-14.
  63. ^ “”Electromagnetic Hypersensitivity: A Systematic Review of Provocation Studies “, 2005”. Psychosomaticmedicine.org. 2005-03-01. http://www.psychosomaticmedicine.org/content/67/2/224.abstract. Retrieved 2011-10-14.
  64. ^ Avendaño, C.; Mata, A.; Villanueva, A.M. Juarez; Martínez, V.S.; Sarmiento, C.A. Sanchez. “Laptop expositions affect motility and induce DNA fragmentation in human spermatozoa in vitro by a non-thermal effect: a preliminary report”. Fertility and Sterility 94 (4): S73. doi:10.1016/j.fertnstert.2010.07.284.
  65. 21714138.

[edit] Further reading

[edit] External links



Source: Wikipedia

Leave a Reply