CSI - An Adaptive Data Pulling Framework for Supporting Time-Critical Streaming Media Applications

数据流的及时交付对于依赖动态数据流的时间关键型应用程序非常重要。数据流发送速率的急剧降低通常会对此类应用的操作产生负面影响。有效的速率自适应是通过缓慢地改变数据流的发送速率来使其适应网络拥塞的需要。本研究项目的动机是需要流动态雷达数据在所需的速率从雷达到控制中心的监视应用中使用gangedground-based雷达。在本研究项目中，我们研究了一种自适应数据拉取框架，以支持稳定的数据流。该框架由传输层拥塞控制机制和应用层数据拉取控制机制组成。应用层的数据拉取控制机制允许应用程序主动地从数据源获取数据。传输层拥塞控制方案采用了一种新的速率控制方法，对数据流提供加权公平性。数据流之间的加权公平性是控制分层编码流的发送速率所期望的特征。加权公平是指当网络拥塞时，流的吞吐量与其优先级成反比地降低，它为数据流的速率控制带来了新的视角。稳定性和对拥塞指示的响应性是新的速率控制方案的两个关键研究问题。

Timely delivery of data streams is important to time-criticalapplications relying on streams of dynamic data. Drastic reductionon the sending rates of data streams typically has negative impact onthe operations of such applications. Effective rate adaptation isneeded to make data streams adapt to network congestion through slowlyvarying their sending rate. This research project is motivated bythe need of streaming dynamic radar data at the required rates fromradars to a control center in the surveillance application using gangedground-based radars. This application is crucial to the operationof the unmanned aerial vehicles.In this research project, an adaptive data pulling framework isstudied to support stable data streaming. This framework consistsof a transport-layer congestion control scheme and anapplication-layer data pulling control mechanism. Theapplication-layer data pulling control mechanism allows theapplication actively fetch data from sources. The transport-layercongestion control scheme adopts a new rate control method whichprovides weighted fairness to data streams. Weighted fairnessamong data streams is the desired feature for controlling the sendingrates of streams carrying layered encodings. Weighted fairnessmeans that the throughput of a stream is degraded reverselyproportional to its priority when the network becomes congested.Weighted fairness brings new vision on rate control for datastreaming. Stability and responsiveness to congestion indicationsare the two key research questions of the new rate control scheme.