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A wireless local area network (WLAN) linkstwo or more devices using some wirelessdistribution method (typically spread-spectrum or OFDM radio), and usuallyproviding a connection through an accesspoint to the wider internet.This gives users the mobility to move aroundwithin a local coverage area and still beconnected to the network.Most modern WLANs are based on IEEE802.11 standards, marketed under the Wi-Fibrand name.
Norman Abramson, a professor at the University ofHawaii, developed the world’s first wireless computercommunication network.In 1979, F.R. Gfeller and U. Bapst published a paper in theIEEE Proceedings reporting an experimental wireless localarea network using diffused infrared communications.The first generation of wireless data modems wasdeveloped in the early 1980s by amateur radiooperators, who commonly referred to this as packetradio.The first of the IEEE Workshops on Wireless LAN was heldin 1991. At that time early wireless LAN products had justappeared in the market and the IEEE 802.11 committeehad just started its activities to develop a standard forwireless LANs.
1.STATIONS2.BASIC SERVICE SET3.EXTENDED SERVICE SET4.DISTRIBUTION SYSTEM
All components that can connect into a wireless medium in a network are referred to as stations. All stations are equipped with wireless network interface controllers .The basic service set (BSS) is a set of all stations that cancommunicate with each other. Every BSS has anidentification (ID) called the BSSID, which is the MACaddress of the access point servicing the BSS.
An extended service set (ESS) is a set of connected BSSs. Accesspoints in an ESS are connected by a distribution system. Each ESShas an ID called the SSID which is a 32-byte (maximum) characterstring.A distribution system (DS) connects access points in an extendedservice set. The concept of a DS can be used to increase networkcoverage through roaming between cells.DS can be wired or wireless. Current wireless distribution systemsare mostly based on WDS or MESH protocols, though other systemsare in use.
An ad-hoc network is a network where stationscommunicate only peer to peer (P2P). There is nobase and no one gives permission to talk. This isaccomplished using the Independent Basic ServiceSet (IBSS).A peer-to-peer (P2P) network allows wireless devicesto directly communicate with each other. Wirelessdevices within range of each other can discover andcommunicate directly without involving centralaccess points. This method is typically used by twocomputers so that they can connect to each other toform a network.
A bridge can be used toconnect networks, typicallyof different types. Awireless Ethernet bridgeallows the connection ofdevices on a wired Ethernetnetwork to a wirelessnetwork. The bridge acts asthe connection point to theWireless LAN.
802.11 RELEASE FREQUENCY BANDWIDTH DATA RATEPROTOCOL DATE (GHZ) (MHZ) (Mbits/s)- JUN 1997 2.4 20 1,2a SEP 1999 3.7 20 6-54b SEP 1999 2.4 20 5-11g JUN 2003 2.4 20 6-54n OCT 2009 5 20 7-74ac NOV 2011 5 160 6.93 (Gbits/s)
• Time and labor costs associated with both wiring and installation of APs and associated networking infrastructure.• Higher performance, reliability, scalability and flexibility.• Seamless mobility between indoor and outdoor networks.• Highly helpful in the places where wires could not be set up for network.