Multiple-input multiple-output (MIMO) technology has been used in wireless local area network (WLAN) systems to enhance system throughput. Many medium access control (MAC) protocols have been proposed for uplink. However, most of them do not consider the operations in physical layer and are difficult to implement in real-world. In this paper, we propose a simple uplink scheme to solve the problem. The main idea is to conduct beamforming in access point such that it can receive signals from multiple users, simultaneously and asynchronously. The distinct advantage of our scheme is that its MAC protocol is compliant to the standard distributed coordination function (DCF) of IEEE 802.11. Simulations show that the proposed scheme significantly outperforms the existing WLAN system.