TKN EDCA Model for ns-2 Sven Wiethoelter, Marc Emmelmann ...

TU Berlin
Chapter 7
Summary
This work describes the final 802.11e amendment with the focus on EDCA. The finally standardized
EDCA backoff was adopted to the older TKN EDCF model, whereby the modified
backoff algorithm has been described in detail. The TKN EDCA model as well as its predecessor
are publicly available together with improvements for ns-2’s legacy WLAN model
at [1].
The verification of the TKN EDCA model has been done—similar to the previous model
version [19]—by comparing its results with previous work [13]. Additionally, the verification
section shows the influence of the modified EDCA backoff algorithm compared to the older
DCF-compliant backoff.
Not only the standardized MAC scheme but also other aspects like conditions of the
wireless channel and the rate adaptation scheme highly influence QoS of delay-sensitive applications.
Therefore, this work finally combines the TKN EDCA model with an underlying
small-scale fading model and the rate adaptation scheme AARF. Results of this application
example show the overhead of VoIP transmissions in an 802.11g/EDCA multi-rate environment
in the presence of small-scale fading and rate adaptation.
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TKN-06-003 Page 18