IEEE 802.11 is the name for a series of protocols for wireless networking. Often. these are referred to as Wireless LAN, WLAN, or Wi-Fi. Such a protocol allows computers that are equipped with special cards to talk with each other, without a cable.
Different standards have different bandwidths[change | edit source]
The first of these standards was made in 1997. It is called IEEE 802.11. It allows communication with 1-2 MBit per second. Today it is outdated, and hardly used any more.
Newer standards have a bandwidth of 54 MBit/s. About 40-50% of this is usable in real-life situations. As of 2007, the standards most widely used are IEEE 802.11g, and IEEE 802.11b. They are compatible with each other.
Currently,standards exist and are labelled IEEE 802.11,802.11a to IEEE 802.11g; h,i,j,n,p and s, are also there, or are planned.
Frequency bands in use[change | edit source]
Data communication is either done in the 2.4 GHz band or in the 5 GHz band. The 2.4 GHz band is a general use band. Microwave ovens and Bluetooth are examples of other things that emit radio waves in this band. IThe 2.4 GHz band has the problem that there are only only very few channels that can be used at the same time, without the signalsinterfering. There are three usable channels there. This means there is a maximum of three networks in the same place. The 5 GHz band can solve some of these problems, but it introduces others. That way, there are 19 usable channels. Overall the band is less used. However there are more regulations. Most devices need to be able to do Dynamic Frequency Selection. Some channels require that those participating can do Transmitter Power Control. Transmitter Power Control is a mechanism to adapt the strength of the signal to what is actually needed. This also helps reduce the amount of interference between different networks.