Vasan, ArunchandarShankar, A. UdayaWe present an empirical, i.e, measurement-based, characterization of the instantaneous throughput of a station in an 802.11b WLAN as a function of the number of competing stations sharing the access point. Our methodology is applicable to practically any wireless MAC protocol. Our findings show that as the number of stations increases, the overall throughput decreases and its variance increases. Furthermore, the per-station performance depends significantly on the wireless card implementation and does not depend as much on the station's processing capacity. UMIACS-TR-2002-69en-USTechnical Report