The Cross-Layer Design for Improving the QoS of Multimedia Streaming Services in Heterogeneous Network Environments

To improve the QoS of multimedia video streaming, in this project we propose a novel cross-layer design for the heterogeneous network environment which consists of wired and wireless networks. Due to higher bit error rate in wireless networks, the effective bandwidth of the wireless network is very unstable. Hence, the wireless network segment often becomes the network bottleneck when the video is streamed from a video server to the wireless clients. That is, under such a heterogeneous network environment the frame error or loss is usually incurred in the wireless network segment. Therefore, the conventional end-to-end (from video servers to mobile clients) error control, flow control and congestion control would be inefficient. To resolve this dilemma, in our proposal a Streaming Agent is attached to the wireless Base Station (BS) or Access Point (AP) to implement effective error control, flow control and congestion control for video streaming. Since the Streaming Agent is an intermediate node between the wired and wireless networks, it can estimate the available bandwidth conditions of both wired and wireless networks using bandwidth estimation schemes. Undoubtedly, it can be the best candidate to control the number of subscribed layers of an SVC (Scalable Video Coding) stream. In addition, another key function of the Streaming Agent is responsible for exchanging related cross-layer information. For example, the presentation time of each video frame residing in the RTP packet header can be passed to the wireless MAC layer for deciding whether to retransmit an error frame or not. Besides, in this proposal the bit error rate of the radio channel in physical layer can also be used to determine the optimal fragmentation size of a MAC frame. Thus, we believe that the throughput of the wireless network can be effectively increased by employing the presented cross-layer design.

Project ID:PB9907-12650
External Project ID:NSC99-2221-E182-011