Link assessment in an indoor 802.11 network

This paper presents the empirical results and analysis of a link variability study for an indoor, stationary 802.11 network subject to external interference. The objective is to characterize the relationships between the packet loss rate on a link and the transmitter-receiver distance, the SNR as reported by the 802.11 card, and time. Experimental results confirm that distance is not predictive of link reliability. Furthermore, attempting to estimate the packet loss rate by counting missing packets can lead to large estimation errors and latency for estimation parameters of practical interest. We find, however, that the SNR measurements reported by today's 802.11 cards can, under certain circumstances, be reliably predictive of the packet loss rate. These results suggest that SNR-based link assessment can provide for more rapid and accurate measurement of link reliability, but they point to the need for improved SNR measurements and models to adequately predict link quality in environments with significant external interference