PhD, September 2006
Monday 25 September 2006
This thesis has a threefold contribution. The first part provides a statistical approach at analysing CSMA/CA type channel access algorithms with the focus on the IEEE 802.11 WLAN standard and delivers novel insights into the structure of the IEEE CSMA/CA access algorithm. The source of the short-term fairness in CSMA/CA type protocols is identified and the classical Jain’s fairness index widely used to quantify short-time fairness is complemented by channel autocorrelation function.
The second part of this work investigates a WLAN/LAN integration scenario in the context of the end-to-end performance of todays Internet protocols with focus on the classical Transmission Control Protocol (TCP). Performance issues of standard TCP in WLAN/LAN integration scenario are identified and an active wireless queue management solution for TCP based on generalised fair cost scheduling call VFQ is presented.
In the third and last part finally, the behaviour of the TCP protocol in simple wireless integration scenarios is analysed and a number of undesirable properties recognised and used to design an improvement of the classical TCP congestion control with focus on the short-time fairness.