Stability And Hopf Branch of A FAST TCP/RED Network Congestion Model with Feedback Control

When a source end adopted FAST TCP to actively control the sending window, and the link end adopted active queue management algorithm, if the network parameters were improperly set, the system can be unstable. The relationship between the stability and network parameters was quantitatively analyzed. Aiming at the defect of network instability caused by radical window halving strategy, a new method based on stability analysis was proposed to make full use of the historical change information obtained by the source-end and to improve the window adjusting strategy of FAST TCP protocol according to the congestion status. Thus, the parameters of the active queue controller was modified indirectly to improve the stability of the system. Ns-2 simulation result verified the accuracy of the stability theory analysis and the effectiveness of the improvement strategy.

Download Full-text

Hopf Bifurcation Control in a FAST TCP and RED Model via Multiple Control Schemes

Journal of Control Science and Engineering ◽

10.1155/2016/8342652 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Dawei Ding ◽

Chun Wang ◽

Lianghui Ding ◽

Nian Wang ◽

Dong Liang

Keyword(s):

Hopf Bifurcation ◽

Time Delay ◽

Feedback Control ◽

Congestion Control ◽

State Feedback ◽

Feedback Controller ◽

Bifurcation Control ◽

Fast Tcp ◽

Hybrid Controller ◽

Control Schemes

We focus on the Hopf bifurcation control problem of a FAST TCP model with RED gateway. The system gain parameter is chosen as the bifurcation parameter, and the stable region and stability condition of the congestion control model are given by use of the linear stability analysis. When the system gain passes through a critical value, the system loses the stability and Hopf bifurcation occurs. Considering the negative influence caused by Hopf bifurcation, we apply state feedback controller, hybrid controller, and time-delay feedback controller to postpone the onset of undesirable Hopf bifurcation. Numerical simulations show that the hybrid controller is the most sensitive method to delay the Hopf bifurcation with identical parameter conditions. However, nonlinear state feedback control and time-delay feedback control schemes have larger control parameter range in the Internet congestion control system with FAST TCP and RED gateway. Therefore, we can choose proper control method based on practical situation including unknown conditions or parameter requirements. This paper plays an important role in setting guiding system parameters for controlling the FAST TCP and RED model.

Download Full-text

THE OPTIMAL FEEDBACK CONTROL OF LINEAR SYSTEMS WITH NON-CHEAP CONTROL

Acta Mathematica Scientia ◽

10.1016/s0252-9602(18)30600-3 ◽

1983 ◽

Vol 3 (2) ◽

pp. 171-182

Author(s):

Qingkai Ye

Keyword(s):

Feedback Control ◽

Linear Systems ◽

Optimal Feedback Control ◽

Optimal Feedback ◽

Cheap Control ◽

Control Of Linear Systems

Download Full-text

IEE South Midland Electronics & Control section: Chairman's address. Feedback control systems

IEE Proceedings D Control Theory and Applications ◽

10.1049/ip-d.1982.0019 ◽

1982 ◽

Vol 129 (3) ◽

pp. 100

Author(s):

R.C. Johnson

Keyword(s):

Feedback Control ◽

Control Systems ◽

Feedback Control Systems ◽

Control Section

Download Full-text

Use of vent stack temperature as a feedforward variable for dissolver total titratable alkali (TTA) control

TAPPI Journal ◽

10.32964/tj17.05.261 ◽

2018 ◽

Vol 17 (05) ◽

pp. 261-269

Author(s):

Wei Ren ◽

Brennan Dubord ◽

Jason Johnson ◽

Bruce Allison

Keyword(s):

Feedback Control ◽

Current Practice ◽

Feedforward Control ◽

Control Variable ◽

Indirect Measurement ◽

Tight Control ◽

Transfer Lines ◽

Green Liquor ◽

Process Dynamics ◽

Downstream Processes

Tight control of raw green liquor total titratable alkali (TTA) may be considered an important first step towards improving the overall economic performance of the causticizing process. Dissolving tank control is made difficult by the fact that the unknown smelt flow is highly variable and subject to runoff. High TTA variability negatively impacts operational costs through increased scaling in the dissolver and transfer lines, increased deadload in the liquor cycle, under- and over-liming, increased energy consumption, and increased maintenance. Current practice is to use feedback control to regulate the TTA to a target value through manipulation of weak wash flow while simultaneously keeping dissolver density within acceptable limits. Unfortunately, the amount of variability reduction that can be achieved by feedback control alone is fundamentally limited by the process dynamics. One way to improve upon the situation would be to measure the smelt flow and use it as a feedforward control variable. Direct measurement of smelt flow is not yet possible. The use of an indirect measurement, the dissolver vent stack temperature, is investigated in this paper as a surrogate feedforward variable for dissolving tank TTA control. Mill trials indicate that significant variability reduction in the raw green liquor TTA is possible and that the control improvements carry through to the downstream processes.

Download Full-text