Encyclopedia of Computer Science and Technology

wireless computing 513the encyclopedia. One tool, WikiScanner, searches for andcompiles information (such as affiliations) about wiki contributors,allowing readers to better judge their competenceand motivations. Wikipedia’s parent Wikimedia Foundationis also introducing a system by which previouslyunknown contributors will undergo a sort of probationaryperiod while their material is scrutinized. (Eventually theywould become “trusted” and their material would appearinstantly, as it does now for most articles.)Wikis have, like blogs, become a pervasive form ofonline communication and information sharing, and havegained considerable attention as an application for the“new” Web (see user-created content, Web 2.0 andbeyond, and social networking). Wikis are currentlybeing used to create rapidly expanding knowledge bases(such as for technical support), to share emerging scholarship,and to promulgate documentation within an organization.Hosting services (called “wiki farms”) such as Wikiaoffer communities wiki software and Web space, sometimesfree of charge. Wiki principles are also finding their wayinto software such as personal information managers (seecontent management).Further ReadingComparison of Wiki Software. Available online. URL: http://en.wikipedia.org/wiki/Comparison_of_wiki_software.Accessed May 11, 2007.Ebersbach, Anja, Markus Glaser, and Richard Heigl. Wiki: WebCollaboration. New York: Springer, 2005.Giles, Jim. “Wikipedia 2.0: Now with Added Trust.” NewScientist.com News Service. Available online. URL: http://technology.newscientist.com/channel/tech/mg19526226.200-wikipedia-20%20-now-with -added-trust.html. Accessed December 4,2007.Klobas, Jane. Wikis: Tools for Information Work and Collaboration.Oxford: Chandos Publishing, 2006.Lee, Ellen. “As Wikipedia Moves to S.F., Founder DiscussesPlanned Changes.” San Francisco Chronicle, November 30,2007. Available online. URL: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/11/30/BUOMTKNJA.DTL. AccessedDecember 3, 2007.Leuf, Bo, and Ward Cunningham. The Wiki Way: Quick Collaborationon the Web. Reading, Mass.: Addison-Wesley, 2001.MediaWiki. Available online. URL: http://www.mediawiki.org.Accessed December 4, 2007.Wikipedia. Available online. URL: http://www.wikipedia.org.Accessed December 4, 2007.Woods, Dan. Wikis for Dummies. Hoboken, N.J.: Wiley, 2007.wireless computingUsing suitable radio frequencies to carry data among computerson a local network has several advantages. The troubleand expense of running cables (such as for Ethernet) inolder buildings and homes can be avoided. With a wirelessLAN (WLAN) a user could work with a laptop on the deckor patio while still having access to a high-speed Internetconnection.Typically, a wireless LAN uses a frequency band witheach unit on a slightly different frequency, thus allowingall units to communicate without interference. (Althoughradio frequency is now most popular, wireless LANs canalso use microwave links, which are sometimes used as analternative to Ethernet cable in large facilities.)Usually there is a network access point, a PC that containsa transceiver and serves as the network hub (it mayalso serve as a bridge between the wireless network and awired LAN). The hub computer can also be connected toa high-speed Internet service via DSL or cable. It has anantenna allowing it to communicate with wireless PCs upto several hundred feet away, depending on building configuration.Each computer on the wireless network has an adapterwith a transceiver so it can communicate with the accesspoint. The adapter can be built-in (as is the case with somehandheld computers), or mounted on a PC card (for laptops)or an ISA card (for desktop PCs) or connected to aUSB port.Simple home wireless LANs can be set up as a “peer network”where any two units can communicate directly witheach other without going through an access point or hub.Applications needing Internet access (such as e-mail andWeb browsers) can connect to the PC that has the Internetcable or DSL connection.A wireless LAN can make it easier for workers who haveto move around within the building to do their jobs. Examplesmight include physicians or nurses entering patientdata in a hospital or store workers checking shelf inventory.ProtocolsSeveral protocols or standards have been developed forwireless LANs. The most common today is IEEE 802.11b,also called WiFi with speeds up to 11 mbps (megabitsper second) transmitting on 2.4 GHz (gigahertz) band.Although that would seem to be fast enough for mostapplications, a new alternative, 802.11n, can offer speedsup to 54 mbps. Because it uses the unlicensed 5 GHzfrequency range it is not susceptible to interference fromother devices.The question of security for 802.11 wireless networkshas been somewhat controversial. Obviously, wirelessdata can be intercepted in the same way that cell phone orother radio transmissions can. The networks come with asecurity feature, WEP or the newer WPA, but many usersneglect to enable it, and it is vulnerable to certain types ofattack. Users can obtain greater security by reducing emissionsoutside the building, changing default passwordsand device IDs, and disabling DHCP to make it harderfor snoopers to obtain a valid IP address for the network.Users can also add another layer of encryption and possiblyisolate the wireless network from the wired networkby using a more secure Virtual Private Network (VPN).Many of these measures do involve a tradeoff between thecost of software and administration on the one hand andgreater security on the other. However, the growing popularityof wireless access should spur the development ofimproved built-in security.Another wireless protocol called Bluetooth has beenembedded in a variety of handheld computers, appliances,and other devices. It provides a wireless connection atspeeds up to 1 MB/second (see Bluetooth).