Comparative Analysis of PCF, DCF and EDCF over IEEE 802.11 WLANs

with the enhancement of wireless network, QoS has become major researcher area. IEEE802.11 standard has two sub layers MAC protocols like as Distribution Coordination Function (DCF), Point Coordination Function (PCF). Medium access coordination function basically implements the Distribution Coordination Function (DCF) and Point Coordination Function (PCF) which support just to best effort service but have limited to QoS services. A new standard, Enhanced Distribution Coordination Function (EDCF) is reported .The IEEE 802.11e (EDCF) which defines the MAC procedures to support QoS requirements and that specifies distribution based access scheme to access the shared wireless media. In this paper, Protocols are tested under realistic conditions to perform evaluation of the coordination functions. Various parameters such as load, network load, media access delay, data dropped are tested in wireless network. Furthermore, the simulative observation is reported at data rate of 66Mbps using a physical layer protocols such as IEEE 802.11n to stumble the best one to implement with EDCF to achieved improved QoS.