Markov Chain Model for EDCA Protocol under Saturation and Non-Saturation Conditions

摘要

IEEE802.11 standards are the most popular techniques used in wireless network. Distributed Coordination Function (DCF) protocol and Enhanced Distributed Channel Access (EDCA) protocol are used in these standards. EDCA protocol is issued to get over the defect in DCF protocol as it does not support Quality of Service (QoS). The mechanism of EDCA protocol is based on dividing the data into four queues: video, voice, best-effort, and background. The priorities are distributed between queues by setting their parameters. In this paper, the Markov chain model is designed to evaluate the throughput of default EDCA protocol in saturation and non-saturation conditions. Our model is designed based on the difference between stations and Access Point (AP) to calculate the uplink and downlink throughput. In addition, the limitation of supporting voice users in EDCA protocol is presented. Moreover, the wireless networks are designed by using the Optimum Network performance (OPNET) simulation to verify the results that have been get from mathematical model. The analysis is also used to explain how the AP is considered as a bottleneck of the network and how it prevents the increase in the number of voice users.