Performance enhancement of the EDCA protocol for the channel access in next generation IEEE 802.11 AX WLAN

Abstract

For supporting Quality of Service (QoS) functionality and differentiated access to the wireless local area network (WLAN) Enhanced Distributed Channel Access (EDCA) protocol was developed in IEEE 802.11e amendment which is the enhancement to the traditional Medium Access Control (MAC) protocol. This protocol sets priority of Audio and Video (AV) traffic over other traffic in the network. Later, a new amendment called IEEE 802.11aa has been introduced which modifies the EDCA protocol using alternate queues for making AV transmission more efficient. Now a days, online streaming of Ultra High Definition (UHD) videos are getting much popular to the users for enhanced user experience. Also, day by day several types of video standards (i.e. 3K, 4K, 8K etc.) are introduced, which have higher resolutions and differential frame rates. But the conventional protocol treats all the video traffic in the same manner which may lead to the unexpected performance degradation of the real time UHD videos. Viewers of online AV streams may experience huge lag in the real time. The amendment of IEEE 802.11aa which was proposed in 2012 also become obsolete and cannot effectively handle QoS support for time critical video traffic. It creates a demand for new way to treat the video traffic in the wireless medium. Hence, we propose the protocol Additional Video Access Queue Based EDCA (AVAQ-EDCA) to address the said issues. Recently, we have got much attention that a new amendment called IEEE 802.11ax is expecting to be announced on 2020 by making big change in Physical and MAC layer features (e.g. introducing OFDM, Spatial Reuse etc.) which will make faster data transmission in the network than ever. Moreover, in such huge contending situation there must need a suitable MAC protocol which can give priority access to UHD video traffic by which we can overcome the unexpected delay of the time critical traffic. In this thesis, by introducing additional queue we restructured the queueing framework of the IEEE 802.11 aa in order to provide a biased priority access of channel for UHD video traffic. Finally, a simulation model based on NS3 network simulator to compare the performance of our proposed AVAQ-EDCA technique with the conventional EDCA mechanism. We also compare our protocol with Robust Wireless Credit Based Shaper Algorithm (RWCBSA) which is a newly developed MAC algorithm based on IEEE 802.11aa alternate queues formula to transmit frames. Simulation results show that our protocol outperforms both conventional EDCA and RWCBSA.