A Pragmatic VBR Stream Scheduling Policy for IEEE 802.11e HCCA Access Method

Nowadays, transferring a variable bit rate (VBR) video streaming on mobile devices is getting popular and necessary. Such traffic streams usually have stringent transferring requirements and in many cases they should be indeed delivered as they were generated. Hence, the IEEE 802.11e hybrid coordination function-controlled channel access (HCCA) access method was proposed to provide better quality-of-service (QoS) requirements for a real-time traffic in the wireless network. However, the reference scheduler of HCCA offered in the standard of the IEEE 802.11e is insufficient for the VBR video stream since it only considers a few characteristics. Hence, choosing the right parameters to meet the QoS requirements of the VBR stream remains an unsolved and opened issue. In this paper, we propose a pragmatic packet scheduling policy for the VBR stream and try to enhance the transmission efficiency for the IEEE 802.11e HCCA access method. The proposed scheduler considers not only traffic characteristics, but also the queue state and the real-time information of the packet. An efficiency analysis is provided to evaluate the transmission efficiency of the proposed scheduler. The result shows that our method can reach higher transmission efficiency than the reference scheduler. Simulations on the transmission of the VBR video stream are also performed to evaluate the performance of the proposed scheme. As it turns out, our design indeed provides a better performance than the reference and other well-known schedulers.