A New Collision Resolution Mechanism for IEEE 802.11 WLAN

Backoff algorithms in traditional distributed contention-based MAC protocols concentrate on adjusting contention window size to resolve collision. However, collision may still occur as long as these windows intersect with each other. In order to solve this problem, we put forward a collision classification model to classify collisions into cross collision and intra collision and suggest to solve them with different manners. Based on this model, we propose collision classification resolution (CCR) algorithm to dynamically allocate discrete distribution windows for collided nodes to avoid cross collision, and the intra collision is resolved with an appropriate distribution window size to achieve a tradeoff between delay and collision probability. The extensive simulations performed demonstrate that compared to IEEE 802.11 DCF, CCR algorithm consistently excels, in terms of collision times, throughput, delay and fairness.