Adaptive Cross-Layer Fragmentation for QoS-based Wireless IPTV Services

International audienceThanks to its cost-effectiveness and wide deployment, the 802.11 WLAN is considered today as the de-facto wireless access network for the last mile connection. In this regards, QoS provisioning in 802.11 WLAN for multimedia services is becoming a main objective that should be enforced to enable reliable commercial offers. To reach this goal, the different mechanisms proposed by 802.11 standards, including fragmentation, physical rate variation, retransmission, and transmission power adjustment, should be exploited intelligently by the application using a cross-layer interaction. This would allow service scalability by improving resources availability and enhancing QoS provisioning. In this paper, we propose an adaptive cross layer fragmentation technique aiming to provide a reliable and QoSbased IPTV service delivery over 802.11 WLAN. In our architecture, the link layer fragmentation is controlled automatically by the application layer in a cross-layer interaction to find a trade-off between the video quality degradation and the overhead ratio introduced by the MAC fragmentation. Performance evaluation conducted using an experimental testbed shows the ability of our cross-layer mechanism to reduce packets video losses and to enhance the overall video objective quality given by the PSNR and the SSIM metrics