In typical installation of an 802.11 based wireless local area network (WLAN), mobile hosts would access the network through access points. Since the communication link between two mobile stations in the same WLAN effectively becomes a two-hop path, even if they can hear each other, the throughput degrades significantly. In fact, when the number of the active mobile stations n increases, the throughput that every mobile station can achieve will decrease in inverse proportion to n/sup 2/. In this paper, we propose the ExDCF protocol as an extension to standard DCF protocol in WLAN, which can improve the throughput between two mobile stations more than twice. Simulation results show that our ExDCF works better in WLAN than the standard DCF while remaining compatible to the standard DCF.