Kendra: adaptive Internet system

This paper describes an audio delivery system model called Kendra. We focus on Kendra's adaptive delivery processes and the experimentation carried ou t to analyse it. The system trades off quality of sound against periods of silence; therefore, adaptation changes the format of the audio data to save bandwidth when bandwidth becomes more scarce. Typically adaptive systems a re composed of a monitoring component and a switching component. The Kendra monitoring component has predictive capabilities, which advise the switchi ng component to adapt either to a better quality or to a more bandwidth fri endly format when it detects lower bandwidth. The prediction element can va ry the amount of data it uses in its prediction, trading-off accuracy with the system's impedance on the performance. Such systems exhibit many other tradeoffs that determine how sensitive and/or optimistic the system is to i ts environment, and this is explored in our experimentation. We conclude ou r work by discussing these network conditions and tradeoffs and how they af fect the performance of the system. (C) 2000 Elsevier Science Inc. All righ ts reserved.