Analyzing the effect of client queue size on VoIP and TCP traffic over an IEEE 802.11e WLAN

In this paper we introduce a mathematical model to analyze the performance of Wi-Fi networks carrying voice calls and TCP controlled file downloads. We derive the voice call capacity, the TCP throughput, and the bandwidth utilization using the proposed five-dimensional Markov model. We show that there exists a correlation among the queue size of client nodes and the capacity and throughput of the network. We also demonstrate how bandwidth utilization is affected by variable packet arrival rates. The analytical results match well with the simulation results generated by Qualnet simulator. Moreover, we conduct an experimental study of the Enhanced Distributed Channel Access (EDCA) mechanism of the IEEE 802.11e standard with a real-environment testbed consisting of 1 access point and 11 laptops to further validate the analytical and simulation results.