Wireless LAN

Technology

The wireless term includes both the cellular phone networks (GSM) and the local networks (WLAN).

WLAN IEEE 802.11 is a standard that allows the interconnection of systems by means of radio-frequency (RF). The main standards in the family of 802.11 are 802.11b e 802.11g operating in the 2,4 GHz frequency, with nominal speed of 11 and 54 Mbps.
The real speed is function of the power of the wireless signal and the number of users contemporary associated to the same access point.

The coverage area of WLAN ranges from a few metres to a few kilometres, function of the obstacles, the angle of transmission, the weather conditions and so on. It is thus possible to link rooms inside a building or buildings across a street (wireless local loop).

Wireless network elements

The elements comprising a wireless network are mainly:

• Access point (AP)
  The access points are the equipments that interconnect the wired networks with wireless networks. .
• Wireless Terminal (WT)
  The Wireless Terminals are the equipments that use the wireless network, associating to AP, by means of PCI, PCMCIA or USB RF card. .
• Authentication system
  The authentication system includes a Radius server which talks with access points and allows or denies the access of wireless terminals.

Application scenario

The services offered on Wireless LAN are the same of wired networks. The over the air transmission has some clear advantages, as the mobility of clients, the avoiding of wires, and so on. .

Some of possible uses of Wireless LAN are: