An Application-Driven MAC-layer Buffer Management with Active Dropping for Real-time Video Streaming in 802.16 Networks

In this paper, we propose an application-driven MAC-layer buffer management framework based on a novel active dropping (AD) mechanism for real-time video streaming in IEEE 802.16 Point-to-Multi-Point (PMP) networks. The basic idea of the proposed approach is that the MAC-layer protocol data units (MPDUs) of a video stream could be actively dropped at the Base Station (BS) if the corresponding frame is not with a sufficient confidence to be successfully delivered to the recipient within its application-layer delay bound. In contrast to the conventional cross-layer techniques that manipulate transmission and/or retransmission priorities for sending MPDUs of a single stream, the proposed AD mechanism can be more effectively bound the delay of each video frame and release precious transmission resources for the subsequent frames or the frames of the other competing streams. This is considered as an intelligent approach for minimizing delay propagation due to bad channels or any other possible reason. A comprehensive analytical model is formulated on deriving how confident a frame can be effectively delivered within its application-layer delay bound by jointly considering the effect of playback buffering. Extensive simulation is performed to demonstrate the effectiveness of the proposed scheme. We expect that the proposed application-driven MAC-layer buffer management can incorporate with the emerging cross-layer design paradigm for real-time video streaming in TDMA-based wireless broadband access networks such as IEEE 802.16.