Performance evaluation of OFDMA in IEEE 802.11ax

Abstract

High speed WiFi has become a necessity now-a-days. The latest standard of WiFi, IEEE 802.11ax, makes use of OFDMA, MU-MIMO, frame aggregation from different access categories, edca protocol, special Trigger frames that start parallel CTS/RTS handshakes, block acknowledgements, preamble, collection of Buffer Status Reports and other features to improve communication quality, to achieve higher throughput, and to reduce latency. These features are employed with the main goal of improving performance of WiFi in dense scenarios like stadiums, halls, colleges, offices, homes, etc. In my work, I compared OFDMA transmissions with OFDM transmissions in 40MHz channel bandwidth on NS3 version 3.34. The simulations are done for a mixed application settings where several stations run different applications and so the flow features to them are different. All simulations were done using WiFi Module provided by NS3. Applications that I covered are Live-Video Streaming, Video-On Demand, Video Conferencing, Web Based Motion Control and HTTP Web Browsing. I have excluded MU-MIMO out of my analysis by keeping only 1 spatial stream. There were 40 stations in environment each running different but 1 application. My main focus was to find out general metrics like aggregate throughput and application-specific metrics like consistency in bitrate of on-demand and live video streaming, consistency in latency for video-conferencing applications, average latency in case of web-based and motion control applications, and finally time to first byte and Page Load Time for stations running Web browsing. Wherever possible and relevant, extensive comparison of the current results has been done with my previous results where I ran all these applications in standalone.