Wireless+LANs

 ** In 1970 University of Hawaii, under the leadership of Norman Abramson, developed the world's first computer communications network using low-cost ham-like radios, named ALOHnet. The bi-directional star topology of the system included seven computers deployed over four islands to communicate with the central computer on the Oahu Island without using phone lines. Originally WLAN hardware was so expensive that it was only used as an alternative to cabled LAN in places where cabling was difficult or impossible. Early development included industry-specific solutions and proprietary protocols, but at the end of the 1990s these were replaced by standards, primarily the various versions of IEEE 802.11 (Wi-Fi) [6].
 * Wireless Local Area Networks (WLANs)
 * History: **

A Wireless Local Area Networks (WLANs) is one in which a mobile user can connect to a local area network (LAN) through a wireless radio connection. In is simply a network linking two or more computers without wires cables. There are IEEE 802.11 standards that specify the technologies for wireless LANs, there are four types of WLAN standards IEEE 802.11- “a”, “b”, “g” and the newest “n”[1]. 
 * WLANs Standards: **

 •  802.11a  o  Data transfer rates up to 54Mbps o  Support more simultaneous connections o  Better at maintaining connections  •  802.11b  o <span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;"> Data transfer speeds up to 11Mbps o <span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;"> Uses hardware that tends to be less expensive o <span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;"> More susceptible to interference o B etter than 802.11a

<span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%; mso-fareast-font-family: Arial;"> • <span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;"> 802.11g o <span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;"> Faster than 802.11b o <span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;"> Data transfer rates up to 54Mbps <span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%; mso-fareast-font-family: 'Courier New';"> o <span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;"> It works in the 2.4 GHz band <span style="color: black; font-family: 'Times New Roman','serif';">

<span style="color: black; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;">

The way WLANs works is that "the network operates by linking the computers to the wiring in the office using radio frequency energy, just as the `cordless' portable telephone in your home sends voice information to the telephone wiring in your home. Like the telephone system, it is a hybrid system using both wired and wireless communication. The antenna is small just a few inches, barely noticeable outside of the computer, and the power used is very low, comparable to your cordless telephone." [1]
 * How WLANs Work:**

<span style="font-family: 'Arial','sans-serif'; font-size: 12pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">• <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Mobility able to move around without the need of wires. <span style="font-family: 'Arial','sans-serif'; font-size: 12pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">• <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Can be expanded and connect several buildings. <span style="font-family: 'Arial','sans-serif'; font-size: 12pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">• <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Easy access to the Internet in public places (conference rooms, hotels, hospitals etc.) <span style="font-family: 'Arial','sans-serif'; font-size: 12pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">• <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Easier to add or move workstations. <span style="font-family: 'Arial','sans-serif'; font-size: 12pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">• <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Easier to provide connection in areas where it is difficult to lay cable. <span style="font-family: 'Arial','sans-serif'; font-size: 12pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">• <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Eliminate the need to pull cable through walls and ceilings. <span style="font-family: 'Arial','sans-serif'; font-size: 12pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">• <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Can access networks from anywhere within range of an access point. <span style="font-family: 'Arial','sans-serif'; font-size: 12pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">• <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Portable or semi-permanent buildings can be connected using a WLAN. <span style="font-family: 'Arial','sans-serif'; font-size: 12pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">• <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Avoid the need to drill holes in walls. [7]
 * <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Advantages **

<span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">Example of Different Types of WLANs





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 * References: **