Autori
Luca De Cicco, Saverio Mascolo and Silviu-Iulian Niculescu
Abstract
Congestion control is a key component of the Internet ensuring network stability since when it was introduced in the Transmission Control Protocol. It has been shown that the plant dynamics can be modelled by means of an integrator, modelling a bottleneck queue, a time delay, modelling the propagation of the information from a source to a destination along with queueing, and a load disturbance, which models the time-varying available bandwidth. A Smith predictor plus a proportional gain is an effective controller, even though, load disturbances cannot be rejected. To overcome this issue, which is particularly relevant in the case of multimedia delay-sensitive traffic, this paper considers the modified Smith predictor proposed by Matausek and Micic as a candidate for the design of a congestion control algorithm. By taking a geometric approach, the trade-off between disturbance rejection property of the modified Smith predictor and the achievable stability robustness with respect to delay uncertainty is quantitatively evaluated. Finally, some guidelines to tune the additional parameter introduced by the modified Smith predictor are proposed.
