Calculating the Frame Collision Probability under IEEE 802.11b DCF

The frame collision probability is an important parameter of the performance modeling. This probability has long been assumed as a value that is determined by the channel characteristics and is independent to the medium access control. The validity of this assumption has not been scrutinized. In this paper, we modeled the CSMA/CA mechanism by a closed-loop model through which the analytical expressions of important probability metrics are derived. These probability metrics include the frame collision probability, the probability of the channel being idle, and the probability that a successful transmission of DATA frame is made. The validity of our modeling is demonstrated by comparing the analytical results with the measurement results obtained from simulations. The analytical results closely approximate the measurement results.