Collision-sequential resolution algorithm in IEEE 802.11 wireless networks

Collision classification is crucial for collision resolution in distributed contention-based MAC protocols. Based on backoff stages the collided nodes stay, this paper classifies collisions into two categories: cross collision and intra collision, and then proves by analysis that cross collision is pervasive in networks, which is verified later by simulation results. Traditional backoff algorithms did not discriminate between these two collisions and treated them alike, which damages the system performance. However, the two collisions should be dealt with different policies and thus propose a novel backoff algorithm featuring Collision-Sequential Resolution (CSR) to address the problem. CSR redistributes the collided nodes in a series of consecutive separated elementary windows according to their occurrence sequence to eliminate cross collision completely. The intra collision is resolved with an appropriate elementary window size to achieve a tradeoff between delay and intra collision probability. Extensive simulations for collision times, throughput, delay and fairness demonstrate that the CSR provides comprehensive improvement compared with traditional backoff algorithms.