The Two-Way Available Bandwidth Estimation Mechanism for Multimedia Streaming Networks

The project proposes a two-way available bandwidth estimation mechanism which is crucial for network flow control, congestion control, and bandwidth management, especially valuable for IPTV systems that adopt Scalable Video Coding (SVC) technique. SVC is employed for transcoding digital contents such that various users with different bandwidth and heterogeneous access network environments (e.g., ADSL, WLAN, WiMAX and 3G) can view the pre-encoded contents by streaming. In addition, SVC can easily support the clients with time-varying bandwidth. Undoubtedly, SVC will eventually become the key technology of IPTV systems. Since SVC encodes each video into multiple layered streams for different quality requirements, all clients need estimate the available bandwidth first in order to decide how many layered streams they can subscribe. If the available bandwidth is not estimated accurately, the viewing quality would be not as expected and even more the network bandwidth utilization can be degraded. On the other hand, the video server may be overloaded if the bandwidth estimations for all clients are conducted at the video server. Thus, it goes without saying that bandwidth estimation conducted by the clients would be more proper than by the video servers. However, almost available bandwidth estimation schemes up to the present are only for one-way. It means that what the client estimated is the uplink bandwidth from the client to the video server rather than the downlink bandwidth used for video streaming. And it is well known that the uplink and downlink are usually not symmetrical in modern networks (e.g., ADSL). It reveals that conventional available bandwidth estimation schemes are not suitable for multimedia networks adopting SVC. Accordingly, the proposal aims to design a two-way available bandwidth estimation mechanism. Our approach uses the concepts of ICMP Timestamp and Traceroute that enable the measurement of packet dispersions in all links of uplink and downlink paths. Additionally, both the fluid cross traffic and packetized cross traffic/bursty cross traffic models are considered so that the two-way available bandwidth estimation can be realized.

Project ID:PB9709-1911
External Project ID:NSC97-2221-E182-039