Power Evaluation and Performance Enhancement of CSMA/CA based WLANs

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) based Wireless Local Area Networks (WLANs) are becoming pervasive. As the most commonly employed standard in WLANs, IEEE 802.11 not only gives rise to health and safety concern from the general public, but also has the potential for enhanced performance. Our contributions in this thesis are twofold: (1) We extend a recently introduced model of transmitted power in WLANs to cover unsaturated conditions when stations do not always have packets to send. we implement an experimental verification of the original analytic model and the extended one. We confirm the estimated maximum power is substantially lower than the International Commission on Non-Ionizing Radiation Protection (ICNIRP) limit; (2) We propose two decentralized Multiple Access Control (MAC) schemes that converge to collision-free schedules almost surely and therefore improve throughput performance. In adopting decentralized learning techniques, the convergence times of both schemes are brief. Decentralized schedule length adaption is introduced to provide long-run fair access to the medium and scalability of the MAC schemes to networks of any size.