How the interference between flows influents the fairness of IEEE 802.11 DCF

IEEE 802.11 DCF protocol exhibit severe fairness problem in many scenarios.In this paper , the reasons why fairness problem appears is given and proved by simulation. The study reveals that the interference among contending MAC flows is different when fairness problem happens. This paper consider that different interference between MAC flows cause the DCF unfair. A parameter named FI (Fairness Indicator) is defined to indicate the interference level of a flow. When the contending flows´ FI values are not same , their capabilities of obtaining channel are different. The flow with smaller FI will get more chance to access channel. Our analysis proved that in order to conquer the fairness problem ,FI must be changed by someway.