An optimized DCF schema with Downlink and Uplink bandwidth control in 802.11 WLAN

In 802.11 infrastructure BSS, the channel throughput will decrease when increasing the number of competing STAs. Also severe asymmetry exists between downlink and uplink data because AP accesses the share channel without any priority. Both problems are solved by a new MAC schema which adjusts the initial contention window of AP and STA to optimized values. A new estimation method for STA number is also proposed via dynamic MAC addresses statistic at AP side. Afterwards, optimized initial contention window values are derived from a mathematical model under downlink and uplink bandwidth control. Simulation indicates that the schema proposed can estimate the channel situation exactly and improve channel throughput with downlink/uplink bandwidth control obviously.