Performance evaluation of a distributed collision resolution protocol for 802.11 wireless LANs

In Wireless Local Area Networks (WLAN), the medium access control (MAC) protocol provides a contention-based distributed channel access mechanism for the stations to share the wireless medium. The MAC protocol is the primary constituent that contributes towards determining the efficiency of sharing the limited communication bandwidth of the wireless channel. The main limitation of the IEEE 802.11 MAC algorithm comes from packet collisions and wasted idle slots due to back-offs during each contention period.; To date, various MAC protocols have been proposed to improve the efficiency of the existing IEEE 802.11 protocol. This thesis involves the study of various elements of the MAC protocol that affect performance efficiency of WLANs. In this thesis different aspects of the Fast Collision Resolution algorithm (FCR) have been evaluated. The FCR redistributes the back-off timers of the stations to avoid possible future collisions, thereby performing a fast collision resolution as the name suggests. It further decreases channel inefficiency by exponentially decreasing the idle time. Further analysis has been performed in terms of collision spaces to understand the impact of various dividing factors on the algorithm. The analyses are corroborated by results obtained through simulations performed using the OPNET network simulator.; The analysis shows that for 20 stations the normalized throughput for FCR with dividing factors 2, 4, and 8 is 19%--21% better when compared to IEEE 802.11.