How WLAN Works - WLAN Tutorial
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Find out here how WLAN works! The best WLAN tutorial and WLAN description.
Terminology and acronyms on this page is explained more in
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Five basic processes will explain you How WLAN works:
1) Scanning - process of finding the network. To use any kind of network, you need to find it first. With wired networks, you have to find a cable or jack on the wall. In wireless world you need to identify an appropriate network. Stations use scanning to find existing networks in the area. After scanning, a station can choose to join one of the BSSs.
In scanning procedure there are seven parameters. Most wireless card drivers use default settings for these parameters. You could change only few of them. I will give you a short description of these parameters, so you could know what they mean.
a) Type of BSS. There are two BSS Types: Ad Hoc and Infrastructure Networks.
b) BSSID - can be an Individual or Broadcast. Access Point chooses which BSSID it will transmit. If AP uses Individual BSSID, then it is “invisible”. Broadcasted BSSID can see all stations in range.
c) SSID (network name) – string by which clients can associate to a specific network.
d) Scan Type is active or passive. Active and passive scanning uses different frames. With active type you can save your battery.
e) Channel List - Scan can use Probe request or listen on a specific channel.
f) Probe Delay - delay in microseconds, before active scanning begins.
g) Minimum and Maximum Channel Time - Minimum and Maximum time before station scans particular channel.
2) Joining - process doesn't guarantee you network access. After joining you need to authenticate and associate, and then you are on the network.
There are two ways how station can join to particular BSS (read Access Point):
- Station can choose BSS manually.
- Automatically - based on power level and signal strength, the station will decide to which access point will join. Parameters on station and Access Point need to match.
3) Authentication is the most discussed issue in wireless networks. In wired networks, physical access to network is the biggest security issue. In wireless world you cannot restrict physical access to network, so you have to use Authentication. It is not mandatory, but my biggest recommendation is to use it.
4) Association is the process, after authentication, that makes you real access to the network. It is similar to plugging into a wired network. 802.11 forbid associating with more than one access point.
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5)The Reassociaton procedure is used when a station moves in network with many access points. Station monitors the signal quality of associated access point and other access points in the same ESS. When station detects that other access point is a better choice, it initiates Reassociaton Procedure.
I hope that you have the now clearer picture of how WLAN works.