|
20/100
|
|
|
802.11a
|
|
|
5 GHz
|
|
|
23 Mbps
|
|
|
54 Mbps
|
|
|
35/120
|
|
|
802.11b
|
|
|
4.3 Mbps
|
|
|
11 Mbps
|
|
|
38/140
|
|
|
802.11g
|
|
|
19 Mbps
|
|
|
802.11n
|
|
|
2.4/5 GHz
|
|
|
74 Mbps
|
|
|
150 Mbps
|
|
|
70/250
|
|
|
When developing its family of standards, the `IEEE 802.11 working group <http://www.ieee802.org/11/>`_ took a similar approach as the `IEEE 802.3 working group <http://www.ieee802.org/3/>`_ that developed various types of physical layers for Ethernet networks. 802.11 networks use the CSMA/CA Medium Access Control technique described earlier and they all assume the same architecture and use the same frame format.
|
|
|
The architecture of WiFi networks is slightly different from the Local Area Networks that we have discussed until now. There are, in practice, two main types of WiFi networks : `independent` or `adhoc` networks and `infrastructure` networks [#fBSS]_. An `independent` or `adhoc` network is composed of a set of devices that communicate with each other. These devices play the same role and the `adhoc` network is usually not connected to the global Internet. `Adhoc` networks are used when for example a few laptops need to exchange information or to connect a computer with a WiFi printer.
|
|
|
An 802.11 independent or adhoc network
|
|
