Wireless Local Area Network (WLAN)

A wireless local area network (WLAN)
A wireless local area network (WLAN) uses radio frequency (RF) technology to transmit and receive data over the air.The Institute of Electrical and Electronics Engineers (IEEE) have established the IEEE 802.11 standard, which is the predominant standard for wireless LANs.Any LAN application, network operating system, or protocol including TCP/IP, will run on 802.11-compliant WLANs as they would over Ethernet

802.11 Standards
The WLAN standards began with the 802.11 standard, developed in 1997 by the IEEE. This base standard allowed data transmission of up to 2 Mbps. Over time, this standard has been enhanced. These extensions are recognized by the addition of a letter to the original 802.11 standard, such as 802.11b.

802.11 b
The 802.11b specification was ratified by the IEEE in July 1999
Radio frequencies in the 2.4 to 2.497 GHz bandwidth of the radio spectrum.
The modulation method selected for 802.11b is known as complementary direct sequence spread spectrum (DSSS) using complementary code keying (CCK) making data speeds as high as 11 Mbps

802.11 a
802.11a operates at radio frequencies between 5.15 and 5.875 GHz.
A modulation scheme known as orthogonal frequency division multiplexing (OFDM) makes data speeds as high as 54 Mbps possible.

802.11 g
802.11g operates at radio frequencies in the 2.4 GHz to 2.497 GHz range (similar to 802.11b), it utilizes the same Orthogonal Frequency Division Multiplexing (OFDM ) modulation allowing for throughput up to 54 Mbps.

Network Requirements
The ease of setting up a WLAN is contributing to its rapid adoption. Reference the following checklist when implementing a new WLAN or expanding an existing WLAN.

Hardware—WLAN consist of two main building blocks including an access point that connects to the network and a wireless adapter installed in the computing device.
Access point—An access point is a small box, usually with one or two antennas. This radio-based, receiver/transmitter is connected to the wired LAN (or broadband connection) using Ethernet cables.
Antennas and bridges—Antennas enhance the radio frequency coverage extending the range of an 802.11 WLAN. Bridges provide point-to-point wireless connection between two LANs, like different floors.
Wireless adapter—A wireless adapter functions like a network interface card (NIC) in that it allows the client computing device access to the network by means of the wireless access point

Security:-
Basic Industry Standard Security: Built into the 802.11b specification, WLAN may be protected by:
Service set identifier (SSID)—A common key that identifies the WLAN. Clients must be configured with the correct SSID to access their WLAN. The key should be shared only with those having legitimate need to access the network so broadcast of SSIDs should be disabled. Also the SSID should be changed periodically.
Media access control (MAC)—Filtering addresses restricts WLAN access to computers that are on a list you create for each access point on your WLAN. This should be enabled.
Wired equivalent privacy (WEP)—Encryption scheme that protects WLAN data streams between clients and APs as specified by the 802.11 standard. This should be turned on.