Modeling and Analyzing for an Improved PCF ...

The RR (Round Robin) scheme adopted in PCF (Point Coordination Function) of WLAN seems difficult to guarantee QoS and satisfy the low delay of the sensitive traffic, yet it can hardly differentiate from priority service for the specific polling station. Thus we develop an improved polling model with priority service, multi-level-polling mechanism and mixed service discipline to enhance the RR scheme. With the help of Embedded Markov Chain and Probability Generating Function Method, we set up the mathematical model for the proposed polling system, and make preparations for the closed form expressions of the system parameters.