A Novel beacon-based collision-free channel access mechanism over IEEE 802.11 WLANs

Development of a Medium Access Control (MAC) protocol that supports high throughput performance and quality of service (QoS) for real-time applications has become a major focus in WLAN research. IEEE 802.11 distributed coordination functions, (DCF/EDCA), provide contention-based distributed channel access for stations to share the wireless medium. However, performance of these mechanisms drops dramatically due to high collision probability and frame errors. In this paper, we propose an adaptive beacon-based collision-free MAC adaptation. The proposed scheme allows station to enter the collision-free state and reduces the number of idle slots regardless of the number of stations and their traffic types (saturated or unsaturated) on the medium. Simulation results indicate that proposed scheme dramatically enhances the overall throughput and supports QoS by reducing delay, jitter and dropping probability of frames.