This paper proposes a novel backoff' algorithm to enhance the Distributed Coordination Function (DCF) function in IEEE 802.11 based wireless networks. The proposed algorithm, known as Pause Count Backoff (PCB) algorithm, observes the number of backoff counter pauses during the channel access contention and sets the appropriate contention window, based on the estimated results. We evaluate the performance of the proposed PCB algorithm using simulation tests and we compare its performance with other proposed IEEE 802.11 backoff algorithms (Exponential Increase Exponential Decrease (EIED), and Adaptive Enhanced Distributed Coordination Function (AEDCF)). Our results demonstrate that PCB outperforms other backoff algorithms in various network conditions. Moreover, the fairness index and end-to-end delay of PCB are also much better than those obtained with other channel access algorithms.