TCP-friendly layered video transmission for the Internet multicast application is investigated in this research. To adapt the available bandwidth in a TCP-friendly manner, a receiver-driven rate adaptation approach based on layered video is used. The receiver adjusts its number of subscription layer based upon the TCP-throughput estimation obtained from our previous work known as smooth and fast rate adaption mechansim(SFRAM). Since SFRAM mitigates unnecessary rate fluctuation and responds only to distinct network variations, a receiver can add or drop a certain number of video layers in a very stable manner. Furthermore, we apply the priority dropping mechanism (PDM) to protect the video layer selectively. To achieve fairness among different flows with PDM, we propose a new packet classification scheme (PCS) to assign the priority to each layer based upon the target rate. Since proposed PCS can also distinguish the priority for packets even within the same layer, it is suitable for Internet video multicast. With PCS, we implement PDM on the random early dropping (RED) queue to drop packets of the lowest priority layer so that end users may avoid instant error propagation. We conduct NS simulations to examine the proposed layer adaptation behavior and the effect of PDM. Our results show that SFRAM is effective enough to direct the right number of subscription layer stably while it behaves in a TCP-friendly manner. Furthermore, PDM on RED can protect layered video of the highest priority effectively with proposed PCS.
A feedback-based Internet video transmission scheme based on the ITU-T H.263+ is presented. The proposed system is capable of continually adjusting the stream size to avoid the congestion in response to network condition changes. It consists of several major components such as TCP-friendly end- to-end congestion control with available bandwidth estimation, encoding frame rate control and transmission buffer smoothing at the server. These components are designed to meet the low computational complexity requirement so that the whole system can operate in real time. Among these, video-aware congestion control, which is called the receiver-based congestion control mechanism (RCCM), and the variable frame rate H.263+ encoding are the two key features. Through a seamless integration of these feature components, it is demonstrated that network adaptivity is enhanced to mitigate the packet loss and the bandwidth fluctuation, resulting in a smoother video experience at the receiver.