Psion Teklogix 9160 G2 Uživatelský manuál stáhnout pdf (Strana 397)

Appendix D: Glossary

802.11e

Psion Teklogix 9160 G2 Wireless Gateway User Manual D-47

tables, acceptable channels, and power levels for each country are provided. Enabling

support for IEEE 802.11d on the access point causes the AP to broadcast which country it is

operating in as a part of its beacons. Client stations then use this information. This is

particularly important for AP operation in the 5GHz IEEE 802.11a bands because use of

these frequencies varies a great deal from one country to another.

802.11e

IEEE 802.11e is a developing IEEE standard for MAC enhancements to support QoS. It

provides a mechanism to prioritize traffic within 802.11. It defines allowed changes in the

Arbitration Interframe Space, a minimum and maximum Contention Window size, and the

maximum length (in kµsec) of a burst of data.

IEEE 802.11e is still a draft IEEE standard (most recent version is D5.0, July 2003). A

currently available subset of 802.11e is the Wireless Multimedia Enhancements (WMM)

standard.

802.11f

IEEE 802.11f (IEEE Std. 802.11f-2003) is a standard that defines the inter access point protocol

(IAPP) for access points (wireless hubs) in an extended service set (ESS). The standard

defines how access points communicate the associations and reassociations of their mobile

stations.

802.11g

IEEE 802.11g (IEEE Std. 802.11g-2003) is a higher speed extension (up to 54 Mbps) to the

802.11b PHY, while operating in the 2.4 GHz band. It uses orthogonal frequency division

multiplexing (OFDM). It supports data rates ranging from 1 to 54 Mbps.

802.11h

IEEE 802.11h is a standard used is to resolve the issue of interference which was prevalent in

802.11a. The two schemes used to minimize interference in 802.11h are Transmit Power

Control (TPC) and Dynamic Frequency Selection (DFS). DFS detects other APs on the same

frequency and redirects these to another channel. TCP reduces the network frequency output

power of the AP, thus reducing the chance of any interference. This is a required standard in

Europe, Japan, and the U.S.

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