We present Wit, a non-intrusive tool that builds on passive monitoring to analyze the detailed MAC-level behavior of operational

wireless networks. Wit uses three processing steps to construct an

enhanced trace of system activity. First, a robust merging procedure combines the necessarily incomplete views from multiple, independent monitors into a single, more complete trace of wireless

activity. Next, a novel inference engine based on formal language

methods reconstructs packets that were not captured by any monitor and determines whether each packet was received by its destination. Finally, Wit derives network performance measures from this

enhanced trace; we show how to estimate the number of stations

competing for the medium. We assess Wit with a mix of real traces

and simulation tests. We find that merging and inference both significantly enhance the originally captured trace. We apply Wit to

multi-monitor traces from a live network to show how it facilitates

802.11 MAC analyses that would otherwise be difficult or rely on

less accurate heuristics.

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In  SIGCOMM

Publisher  Association for Computing Machinery, Inc.
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