A Cross-Layered Network-Adaptive Video Streaming over WLAN: Channel Monitoring and Video Rate Adaptation

To realize the real-time network-adaptive video streaming service over bandwidth-scarce and fluctuating WLAN, an effective channel monitoring scheme is required. In this paper, we propose a cross-layered network-adaptive streaming system where an intelligent intermediate sender with an embedded wireless access point estimates the time-varying channel condition (namely, Sender-side Cross-Layered Monitoring: CLMS). For a given monitoring interval, the CLMS estimates the available time resource for actual data transmission (i.e., channel time) by using observed MAC (medium access control) and PHY (physical) statistics. A streaming sender, which has an interface with the CLMS, then dynamically adjusts the scalability of video (e.g., temporal scalability) according to the estimated channel condition. Evaluation results over the IEEE 802.11a WLAN testbed is provided to verify the intended QoS (quality of service) adaptation capability. The experimental results show that the proposed system with the CLMS can effectively mitigate the quality degradation of video streaming caused by the fluctuations of time-varying wireless channel condition.