Performance Analysis of IEEE 802 . 11 DCF : Throughput , Delay , and Fairness

Throughput, delay, and fairness are three most important performance metrics in IEEE 802.11-based wireless networks. In this paper, we provide a simple but precise analytical model to evaluate the above three metrics. Different from the pr evious models that have focused either on throughput or on delay, our model is unique as we obtain throughput, delay, and fairness all together. Moreover, by considering the fact that a packet may be dropped after a finite number of retrials, we distinguish five cases of packet delay, and derive the relationship among them. Using the proposed model, we carry out an extensive and insightful performance evaluation of IEEE 802.11 under different system parameters. Our results show that the throughput, dela y, and fairness are quite sensitive to the system parameters being chosen, demonstrating the importance of performing dynamic tuning of the system parameters in IEEE 802.11. Moreover, the optimal values of the parameters are inconsistent with each other for different performance metrics, implying that some tradeoff among the metrics must be made in the dynamic tuning. Finally, our results also show that the previous models have overestimated the throughput as well as the packet delay.