MAC Layer Assisted Localization in Wireless Environments with Multiple Sensors and Emitters

Localization is especially challenging in extreme RF emitter density (EED) environments (e.g. football stadiums), in part due to ambiguity in associating localization measurements to the correct emitter. One approach is to use other physical layer features for data association, but such techniques may not scale well for many emitters. This paper proposes exploiting the structure provided by the MAC layer for data association. The idea is explored in the context of IEEE 802.11g by using knowledge of the packet exchange sequence (PES), virtual carrier sense, and CSMA/CA to lower the probability of association error (PE) compared to a signal-to-noise ratio (SNR)-based OSI layer 1 strategy. Analytical expressions are derived for the PE on both a per packet detection and per packet exchange sequence basis. The proposed strategy lowers PE over an entire RTS/CTS sequence and scales well asymptotically in the number of emitters. The results are specific to WLANs, but the idea and approach are broadly applicable to any communications protocol with a MAC layer.