QoS/QoE support for H.264/AVC video stream in IEEE 802.11ac WLANs

The H.264 video compression technique enjoys the merit of good video quality with high compression rate; therefore, it has been widely applied in delivering video content. In IEEE 802.11ac wireless local area networks, enhanced distributed channel access (EDCA) is the primarily adopted access control mechanism for multimedia traffic transmission. However, the performance is degraded due to the unpredictable delay caused by its inefficient backoff procedure. To achieve high quality of service/experience, this paper proposes a multipolling controlled access (MPCA) scheme to guarantee the latency in delivering important video frames while reducing transmission overhead.We also propose a cross-layer designed quality adjustment strategy to maximize the visual experience. Furthermore, the downlinkmultiuser multiple-input-multiple-output feature in IEEE 802.11ac is exploited to enhance the reliability of MPCA. Theoretical analysis is provided to show high efficiency of MPCA. Simulation results indicate that MPCA has higher throughput, lower packet delay, lower packet loss, and higher peak signal-to-noise ratio than the EDCA.