A Dynamic Mechanism for Tunning MAC Parameters to Improve Video Transmission in Wireless LANs

With the increasing growth of multimedia communications on the Internet, on the one hand, and with the expansion of deployment of wireless networks on the other hand, the quality of video transmission on these networks has become a major challenge. The 802.11e standard proposes a framework to provide the Quality of Service (QoS) in accordance with the type of traffic and which is used by next variants of the standard, namely, 802.11n and 802.11ac. One of the channel access mechanisms in this standard is EDCA, which has predicted four separate queues for different types of traffic. This mechanism defines distinct channel access parameters in each queue. In this paper, a dynamic method is provided for tunning the access parameters in each queue, such as the size of the Contention Window (CW), and Arbitration Inter-Frame Space (AIFS), which calculates their decrease or increase based on the varying network conditions. However, the average collision rate is used to determine the network load conditions. This criterion is calculated with a weighted average of each queue at each station and updated every time the packet is sent. The simulation results in NS2 indicate that the proposed method improves the quality of video transmission from the point of view of multiple criteria, including PSNR, throughput, packet loss rate and the end-to-end delay