A Multimedia Priority Dynamic Scheduling Scheme for Audio-Video Transmission with User-Level QoS Guarantee by IEEE 802.11e HCCA

This paper studies packet scheduling schemes for audio-video transmission in a wireless LAN with HCF controlled channel access (HCCA) of the IEEE 802.11e MAC protocol. We first propose two kinds of scheduling schemes which are referred to as the static scheduling (SS) and multimedia priority dynamic scheduling (MPDS). In the SS scheme, the hybrid coordinator (HC) allocates the duration of transmission opportunity (TXOP) for each station statically. The TXOP duration in the SS scheme can be shorter or longer than that in the reference scheduler of the IEEE 802.11e standard. On the other hand, in the MPDS scheme, the HC first allocates the duration of TXOP to each station according to the SS scheme; it then gives additional TXOP duration to stations which had audio or video packets in their source buffers at the end of the previous TXOP. We then compare the SS scheme, the MPDS scheme, and the reference scheduler in terms of application-level QoS and user- level QoS (perceptual QoS). Numerical results show that the SS and MPDS schemes can accommodate a larger number of multimedia stations in a cell than that of the reference scheduler under the condition that user-level QoS is kept high.