Optimization of IEEE 802.11e Access Class Parameters with Cross-layer Approach

The aim of this paper is to analyze the performance of diverse applications in a wireless scenario based on the IEEE 802.11e standard. In particular, TCP-based traffic (several TCP versions was be used, such as: TCP NewReno, SACK, and Westwood+) and UDP-based traffic was considered referring to FTP download and VoIP applications, respectively. Tests carried out in the ns-2 environment have permitted to evaluate quality of service issues and the cross-layer impact on the transport layer due to EDCA parameters. The interest is here on the selection of the contention window sizes for different IEEE 802.11e access classes in order to guarantee a good performance for both TCP-based and UDP-based traffic flows.