MODELING AND EMPIRICAL ANALYSIS OF IEEE 802.11b DISTRIBUTED COORDINATION FUNCTION (DCF) IN A  MULTI-RATE WIRELESS LAN

MODELING AND EMPIRICAL ANALYSIS OF IEEE 802.11b DISTRIBUTED COORDINATION FUNCTION (DCF) IN A  MULTI-RATE WIRELESS LAN

ABSTRACT

Distributed coordination Function is the most crucial component of IEEE 802.11 standard. It is a media access control (MAC) scheme used by the IEEE 802.11. Because the channels used by wireless devices is a time-varying broadcast medium, these devices need to have multi-rate and rate adaptive capability to adapt to the changing channel so that better performance can be achieved. In this work, an analytical model is presented to study the throughput and delay variation of IEEE 802-11b with number of mobiles in a multi-rate WLAN using the DCF protocol to contend for data transmissions in a slowly-varying channel. Auto Rate Fall back (ARF) protocol was used to adapt rates for different channel qualities and the best configurations and parameter values for the ARF in correspondence to network load and topology to get best performance was discussed.