Two-Phase Collision Avoidance to Improve Scalability in Wireless LANs

IEEE 802.11 DCF exhibits poor scalability due to the large contention overhead. Therefore, the more the number of stations, the less the aggregate throughput. The authors propose a two-phase collision avoidance scheme to reduce the collision probability and to enhance the throughput performance. In their proposed scheme, contention among stations is resolved in two phases: SuperSlots and SubSlots. Also, their truncated backoff mechanism increases the throughput by reducing the idle time slots. The authors analyze the performance of the authors proposed scheme based on the previous analysis of 802.11 DCF.