  Common WLAN pathologies include low signal-to-noise ratio, congestion, hidden
terminals or interference from non-802.11 devices and phenomena. Prior work has
focused on the detection and diagnosis of such problems using layer-2
information from 802.11 devices and special-purpose access points and monitors,
which may not be generally available. Here, we investigate a userlevel
approach: is it possible to detect and diagnose 802.11 pathologies with
strictly user-level active probing, without any cooperation from, and without
any visibility in, layer-2 devices? In this paper, we present preliminary but
promising results indicating that such diagnostics are feasible.
