Understanding link-layer behavior in highly congested IEEE 802.11b wireless networks

The growing deployment and concomitant rise in wireless network usage necessitates the comprehensive understanding of its behavior. More importantly, as networks grow in size and number of users, congestion in the wireless portion of the network is likely to increase. We believe there is a strong need to understand the intricacies of the wireless portion of a congested network by interpreting information collected from the network. Congestion in a wireless network can be best analyzed by studying the transmission of frames at the link layer. To this end, we use vicinity sniffing techniques to analyze the link layer in an operational IEEE 802.11b wireless network. In this paper, we discuss how congestion in a network can be estimated using point-to-point link reliability. We then show how link reliability is correlated with the behavior of link-layer properties such as frame retransmissions, frame sizes, and data rates. Based on the results from these correlations, our hypothesis is that the performance of the link layer in congested networks can be improved by (1) sending smaller frames, and/or (2) using higher data rates with a fewer number of frames sent.