In this work, we proposes an adaptive service differentiation scheme called AEDCF (Adaptive EDCF) for QoS enhancement in 802.11 wireless ad-hoc networks. In our scheme, relative priorities are provisionedby adjusting the size of the Contention Window of each traffic class taking into account both applications requirements and network conditions. We evaluate the performance of AEDCF and compare it with the EDCF scheme proposed in the upcoming standard of 802.11e.  Results show that AEDCF outperforms the basic EDCF, especially at high traffic load conditions. Indeed, our scheme increases the medium utilization ratio and reduces for more than 50% the collision rate. While achieving delay differentiation, the overall goodput obtained is up to 25% higher than EDCF. Moreover, the complexity of AEDCF remains similar to the EDCF scheme,
enabling the design of cheap implementations.

Copyright: You can download our ns codes freely for academic use,  but please cite our contribution when you use it: 

          ns-802.11.AEDCF source codes
 

          Qiang Ni, Oct .30, 2002