International Journal of Computer Theory and Engineering

Abstract

The awareness of channel conditions is critical to routing and MAC protocols. But, it is challenging to assess channel conditions due to the highly dynamic nature of wireless links. As a succession to a study of IEEE 802.11 links in an indoor environment, this paper presents observations and analysis of extensive measurements on IEEE 802.11 channels in an outdoor environment. The experiments are designed to investigate the channel dynamics through metrics such as successful frame delivery rate, loss rate, and Signal-to-Noise Ratio on IEEE 802.11 networks. The objective of this work is to reveal the interaction between these metrics and their variations in time and space. The following observations were obtained. The frame delivery rate for fixed stations fluctuates over time in most scenarios. Statistics over large time intervals get bursty and do not provide valuable information about channel conditions. Generally, Signal-to-Noise Ratio (SNR) varies widely over time even for fixed stations. However, the SNR remains stable for micro time scales. As a consequence, the frame delivery does not strongly correlate with SNR. If sent at a favorable time, a set of frames is likely to be delivered successfully continuously.