Quick end-to-end available bandwidth estimation for QoS of real-time multimedia communication

We propose PathQuick, a quick end-to-end available bandwidth estimation method. When PathQuick is used in real-time multimedia communication, such as real-time photo sharing and video conferencing, just before the transmission of media data such as photo and video, it can quickly complete the estimation of the latest available bandwidth. Consequently, the bandwidth consumption of media data can be controlled to within the available bandwidth estimated at the beginning of media data transmission, and this will prevent delay and packet loss. Thus, QoS at the beginning of real-time photo sharing and video conferencing can be ensured. Conventional methods have a critical restriction that they require a long estimation time; e.g., several seconds or several ten seconds. Using these methods just before the media data transmission causes an unacceptably long waiting time until media data transmission begins, thus degrading real-time responsiveness. PathQuick achieves quick estimation by using a probing packet train (i.e., a set of multiple probing packets) with distinctive features: each packet within the packet train is placed at an equal time interval, and each packet size linearly increases as the packet sequence proceeds. Our evaluation of PathQuick has shown that its estimation duration is several hundred milliseconds, which is more than four times as fast as a conventional method. We also found that its probable range is more than a hundred times as wide as that of the conventional method when a limited waiting time is set to avoid degrading real-time responsiveness.