This paper assesses application-level QoS and user-level QoS (i.e., perceptual QoS) in the case where audio and video streams are transferred with the EDCA (Enhanced Distributed Channel Access) of the IEEE 802.11e MAC. In the EDCA, a station can transmit multiple MAC frames during a TXOP (Transmission Opportunity); this is referred to as TXOP-bursting or CFB (Contention Free Bursting). By simulation, we first examine the effect of the TXOP-bursting on application-level QoS in the presence of transmission errors and associated retransmission of MAC frames. Simulation results show that the TXOP-bursting can improve average video MU (Media Unit) delay, MU loss ratio, and media synchronization quality, particularly when the AP (Access Point) sends audio and video streams to stations in the downlink direction. Furthermore, we assess user-level QoS by the method of successive categories, which is a psychometric method. Numerical results show that the TXOP-bursting can also improve the user-level QoS.
['Takahiro Suzuki', 'Atsunori Noguchi', 'Shuji Tasaka']
Effect of TXOP-Bursting and Transmission Error on Application-Level and User-Level QoS in Audio-Video Transmission with IEEE 802.11e EDCA