Robust stability analysis of Smith predictor-based congestion control algorithms for computer networks

• Published in: Automatica (Oxford) Vol. 47; no. 8; pp. 1685 - 1692
• Main Authors: De Cicco, Luca, Mascolo, Saverio, Niculescu, Silviu-Iulian
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.08.2011; Elsevier
• Subjects: Applied sciences; Automatic Control Engineering; Computer Science; Computer science; control theory; systems; Computer systems and distributed systems. User interface; Congestion; Congestion control; Control systems; Delay; Dynamical Systems; Exact sciences and technology; Internet; Mathematics; Networks; Robust stability; Smith predictor; Software; Switching theory; TCP (protocol); Time delay systems; Uncertainty; Robust stability; Smith predictor; Congestion control; Time delay systems; Closed loop; Packet switching; Transmission protocol; Transmission control protocol; Resource sharing; Delay system; Computer control; Distributed system; Geometrical model; Bounded delay; Traffic management; Distributed control; Integrator; Delay time; Data field; Internet; Queue; Traffic congestion; Switching networks
• ISSN: 0005-1098; 1873-2836
• DOI: 10.1016/j.automatica.2011.02.036

Congestion control is a fundamental building block in packet switching networks such as the Internet due to the fact that communication resources are shared. It has been shown that the plant dynamics is essentially made up of an integrator plus time delay and that a proportional controller plus a Smith predictor defines a simple and effective controller. It has also been shown that the TCP congestion control can be modelled using a Smith predictor plus a proportional controller. Due to the importance of this control structure in the field of data network congestion control, we analyse the robust stability of the closed-loop system in the face of delay uncertainties that are present in data networks due to queuing. In particular, by applying a geometric approach, we derive a bound on the proportional controller gain which is necessary and sufficient to guarantee the closed-loop stability for a given bound on the delay uncertainty.