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IEEE 802.11s

The IEEE 802.11s working group is concerned with the meshing of radio systems. Since radio systems such as WiMax, WLAN or Ultra Wideband( UWB) have high data rates, but can only transmit them over limited distances, the focus is on area-wide HS radio systems. With these concepts, the base stations have to be connected to each other, which was previously done by wire, i.e., via data cables.

To reduce this effort, IEEE 802.11s specifies a mesh network( WMN) in which mesh access points( MAP) are wirelessly interconnected to form a wireless distribution system( WDS). The individual devices of a mesh network, the Mesh Stations (Mesh STA), form the mesh connections among themselves, over which a path is established using a routing protocol. In addition to the mesh point( MP), 802.11s also defines a lightweight mesh point( LW-MP), which has no forwarding function.

Configuration of a mesh network for WLANs according to 802.11s

Configuration of a mesh network for WLANs according to 802.11s

The 802.11s concept essentially consists of dynamic path selection, changes in channel access and the security concept.

The path selection for WLAN meshes is based on the link layer, which makes layer 3 protocols, such as the IP protocol, transparent. Since there are no dedicated connections between two end devices in wireless networks, multicast is implemented by filtering broadcast packets in the receiver. Endless forwarding of data packets is prevented by means of corresponding data fields. The optimal mesh station connections are found using the HWMP protocol (Hybrid Wireless Mesh Protocol).

Mesh Access Point, Photo: Frontier PC

Mesh Access Point, Photo: Frontier PC

Since channel access using Enhanced Distributed Channel Access( EDCA) has certain performance limitations in mesh networks, various alternative methods such as the Common Channel Framework( CCF) or Mesh Deterministic Access( MDA) are being discussed as part of the standardization process.

Informations:
Englisch: IEEE 802.11s
Updated at: 27.05.2014
#Words: 289
Links: IEEE 802, working group (WG), ultra wideband (802.15, ZigBee) (UWB), data, area
Translations: DE
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