IEEE 802.11 distributed coordination function (DCF) is a distributed medium access scheme based on carrier sense multiple access with collision avoidance (CSMA/CA) protocol. Many literatures have analyzed the performance of IEEE 802.11 DCF. However, such literatures either used simulation methods or built the analytical models under the assumption that the saturation condition was satisfied. To overcome such a problem, in this paper, a bi-dimensional Markovian model has been introduced to depict the DCF mechanism. The proposed model introduced an idle stage and a discrete time M/G/1 queue to deduce the channel throughput under finite load traffic. Simulation results proved the accuracy of the proposed model.