What is a WLAN?

A WLAN, or wireless local area network, is a computer network - or part thereof - that incorporates wireless devices. A conventional LAN (local area network) - as used in a home or small office network - incorporates two or more PCs connected to an Ethernet hub using network cables. This conventional LAN setup can be extended to include wireless devices using an access point. Although wireless networks can be completely independent of conventional networks, a WLAN usually forms part of an existing wired network.

What is an access point?

An access point is required to connect PCs with wireless cards to an existing LAN. An access point is like a transceiver (transmitter-receiver) that translates between wireless network traffic and wired network traffic, acting as a gateway between the two.

An access point resides on a LAN the same way a PC does -- via a network cable. It is assigned its own IP address, and can be connected to by other PCs on the LAN. While the IP address can be set manually, it is common to have one assigned automatically by a DHCP server. This task is usually performed by a router where ADSL Internet connection sharing is in place, or a domain server in more conventional IT networks.

As well as being located on the LAN, an access point is also the centre of a wireless network. Wireless devices in the vicinity can connect to the access point via radio waves and these transmissions are converted by the access point into IP traffic on the network.

Some access points are also capable of communicating with other access points using a protocol called Ethernet over AP. These can be used to extend the range of a WLAN. In recent years it is more common to find access points that have integrated routers and, sometimes, broadband modems. An access point with a built-in router can be used as the central hub of a LAN with WLAN capabilities. The router component allows the device to connect to remote networks such as the Internet for maximum connectivity.

What is the range of wireless?

Although wireless transmission ranges vary greatly and lowering the bandwidth will increase the coverage area, a standard 802.11b or 802.11g device will typically have a range of about 30m indoors and up to 120m line-of-sight outdoors. Devices using the higher frequency 802.11a protocol will have a range of about 12m indoors and 30m line-of-sight outdoors.

The main reason for the variance between indoors and line-of-sight coverage is that walls and other objects do impede the wireless signal. Because wireless transmissions are actually low frequency radio waves, they will pass through walls and other solid matter relatively easily. Bear in mind, though, that as the distance increases, the throughput decreases. This is because lower signal strength will result in dropped packets and result in a general decrease in network efficiency.