WLC29-4: 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. We propose a two-phase collision avoidance scheme to reduce the collision probability and to enhance the throughput performance. In our proposed scheme, contention among stations is resolved in two phases: SuperSlots and SubSlots. Also, our truncated backoff mechanism increases the throughput by reducing the idle time slots. We analyze the performance of our proposed scheme based on the previous analysis of 802.11 DCF. Both the analysis and simulation results exhibit that our proposed scheme achieves higher throughput than the current IEEE 802.11 backoff mechanism, and this differential increases with the number of stations in the network.