Application-Level QoS and QoE Assessment of Audio-Video Transmission with TXOP-Bursting by IEEE 802.11e EDCA

摘要

This paper assesses application-level QoS and Quality of Experience (QoE) in the case where audio and video streams are transferred with the enhanced distributed channel access (EDCA) of the IEEE 802.11 e MAC. In EDCA, a station can transmit multiple MAC frames during a transmission opportunity (TXOP); this is referred to as TXOP-bursting. By simulation, we first compare application-level QoS with the TXOP-bursting scheme and that vithout the scheme for various distances between access point (AP) and sta ions. In this paper, we suppose that the bit error rate (BER) becomes lager as the distance increases. Numerical results show that TXOP-bursting can improve many metrics of video quality such as average media unit (MU) delay, MU loss ratio, and media synchronization quality, particularly when the AP sends audio and video streams to stations in the downlink direction. We then examine the effect of TXOP_(Limit) on the video quality. Simulation results show that the video quality can be degraded if the value of TXOP_(Limit) is too small. Furthermore, we assess QoE by the method of successive categories, which is a psychometric method. Numerical results show that TXOP-bursting can also improve the QoE. We also perform QoS mapping between application-level and user-level with principal component analysis and multiple regression analysis.