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WLAN architecture

Wireless networks according to IEEE 802.11 are divided into radio cells. A radio cell consists of at least one transmitter/receiver pair and is defined as the space in which all transmitters and receivers use the same frequency and/or the same code. Depending on the extent of the individual radio cells, a distinction is made between picocells, microcells and macrocells.

Such a wireless functional area is called Basic Service Area (BSA), the functionality is called Basic Service Set (BSS). If several simple BSSs are combined to form a functional unit, this is referred to as the Extended Service Set (ESS).

The central component of a WLAN is the access point (AP). It performs central network functions such as filtering or roaming, is directly connected to the wired networks and maintains radio links to other network nodes and to the wireless terminals. It determines the radio range, the radio cell. To extend an access point range, there is the wireless repeater, which is directly connected to the access point and transmits on the same channel as the access point.

Wireless access point for 802.11, Photo: Cisco

Wireless access point for 802.11, Photo: Cisco

The wireless bridge is used for the topological expansion of a WLAN. It can be used to wirelessly connect wired LAN segments to the access point. This allows a large number of users to work simultaneously via the wireless connection.

Areas by Wireless LANs

Areas by Wireless LANs

A similar function is performed by the station adapter, to which up to four personal computers (PCs) can be connected via a normal Ethernet interface. The station adapter is equipped with small omnidirectional antennas and uses them to establish the connection to the access point.

The end devices of a WLAN are equipped with WLAN PC cards or WLAN sticks, i.e. wireless network cards or wireless network interface controllers (WNIC). These perform the functions of transmitting/receiving, modulating/demodulating and encoding/decoding.

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Englisch: WLAN architecture
Updated at: 05.01.2012
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