Wireless Local Area Networks: History and Types of WLAN

Topics: Wireless LAN, Wi-Fi, IEEE 802.11 Pages: 6 (1974 words) Published: August 8, 2010
Wireless Local Area Networks (WLANs)
A wireless LAN (or WLAN, for wireless local area network, sometimes referred to as LAWN, for local area wireless network) is one in which a mobile user can connect to a local area network (LAN) through a wireless (radio) connection. The IEEE 802.11 group of standards specify the technologies for wireless LANs. 802.11 standards use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing and include an encryption method, the Wired Equivalent Privacy algorithm.

Wireless Local Area Networks (WLANs) have moved quickly to the mainstream and are now found in many educational institutions, homes, businesses and public areas. Organizations and consumers have been keen to take advantage of the flexibility adding wireless networks can offer. A recent report from In-Stat predicts that the wireless market will grow from 140 million wireless chipsets a year in 2005 to 430 million in 20091. The emergence of new security standards has also increased confidence in WLANs. Users are becoming more familiar with the technology and are increasingly expecting wireless access to be available. There is a wide range of products and standards involved in WLAN technology and more continue to emerge. This paper will focus on wireless LANs and the issues surrounding their implementation.

In 1970, Norman Abramson, a professor at the University of Hawaii, developed the world’s first computer communication network, ALOHA net, using low-cost ham- like radios. With a bidirectional star topology, the system connected seven computers deployed over four islands to communicate with the central computer on the Oahu Island without using phone lines. "In 1979, F.R. Gfeller and U. Bapst published a paper in the IEEE Proceedings reporting an experimental wireless local area network using diffused infrared communications. Shortly thereafter, in 1980, P. Ferrert reported on an experimental application of a single code spread spectrum radio for wireless terminal communications in the IEEE National Telecommunications Conference. In 1984, a comparison between infrared and CDMA spread spectrum communications for wireless office information networks was published by Kaveh Pahlavan in IEEE Computer Networking Symposium which appeared later in the IEEE Communication Society Magazine. In May 1985, the efforts of Marcus led the FCC to announce experimental ISM bands for commercial application of spread spectrum technology. Later on, M. Kavehrad reported on an experimental wireless PBX system using code division multiple access. These efforts prompted significant industrial activities in the development of a new generation of wireless local area networks and it updated several old discussions in the portable and mobile radio industry. The first generation of wireless data modems was developed in the early 1980s by amateur radio operators, who commonly referred to this as packet radio. They added a voice band data communication modem, with data rates below 9600-bit/s, to an existing short distance radio system, typically in the two meter amateur band. The second generation of wireless modems was developed immediately after the FCC announcement in the experimental bands for non- military use of the spread spectrum technology. These modems provided data rates on the order of hundreds of KB/s. The third generation of wireless modem then aimed at compatibility with the existing LANs with data rates on the order of MB/s. Several companies developed the third generation products with data rates above 1 MB/s and a couple of products had already been announced by the time of the first IEEE Workshop on Wireless LANs. 54 MB/s WLAN PCI Card (802.11g).

"The first of the IEEE Workshops on Wireless LAN was held in 1991. At that time early wireless LAN products had just appeared in the market and the IEEE 802.11 committee had just started its activities to...
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