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    A compensated PID active queue management controller using an improved queue dynamic model

    , Article International Journal of Communication Systems ; Vol. 27, issue. 12 , 2014 , pp. 4543-4563 Kahe, G ; Jahangir, A. H ; Ebrahimi, B ; Sharif University of Technology
    Abstract
    Beside the major objective of providing congestion control, achieving predictable queuing delay, maximizing link utilization, and robustness are the main objectives of an active queue management (AQM) controller. This paper proposes an improved queue dynamic model while incorporating the packet drop probability as well. By applying the improved model, a new compensated PID AQM controller is developed for Transmission Control Protocol/Internet Protocol (TCP/IP) networks. The non-minimum phase characteristic caused by Padé approximation of the network delay restricts the direct application of control methods because of the unstable internal dynamics. In this paper, a parameter-varying dynamic... 

    AQM controller design for TCP networks based on a new control strategy

    , Article Telecommunication Systems ; Volume 57, Issue 4 , December , 2013 , Pages 295-311 ; 10184864 (ISSN) Kahe, G ; Jahangir, A. H ; Ebrahimi, B ; Sharif University of Technology
    Kluwer Academic Publishers  2013
    Abstract
    When the network suffers from congestion, the core or edge routers signal the incidence of congestion through the active queue management (AQM) to the sources. The time-varying nature of the network dynamics and the complex process of retuning the current AQM algorithms for different operating points necessitate the development of a new AQM algorithm. Since the non-minimum phase characteristics of the network dynamics restrict direct application of the proportional-integral-derivative (PID) controller, we propose a compensated PID controller based on a new control strategy addressing the phase-lag and restrictions caused by the delay. Based on the unstable internal dynamics caused by the... 

    A self-tuning controller for queuing delay regulation in TCP/AQM networks

    , Article Telecommunication Systems ; 2018 ; 10184864 (ISSN) Kahe, G ; Jahangir, A. H ; Sharif University of Technology
    Springer New York LLC  2018
    Abstract
    AQM router aims primarily to control the network congestion through marking/dropping packets which are used as congestion feedback in traffic sources to balance their flow rate. However, stabilizing queuing delay and maximizing link utilization have been considered as the main control objectives, especially in media dominated networks. Usually, most of the AQM algorithms are designed for a nominal operating point. However, time-varying nature of network parameters frequently violates their robustness bounds. In this paper, a self-tuning compensated PID controller is proposed to address the time-varying nature of network conditions caused by parameter variations and unresponsive connections.... 

    A self-tuning controller for queuing delay regulation in TCP/AQM networks

    , Article Telecommunication Systems ; Volume 71, Issue 2 , 2019 , Pages 215-229 ; 10184864 (ISSN) Kahe, G ; Jahangir, A. H ; Sharif University of Technology
    Springer New York LLC  2019
    Abstract
    AQM router aims primarily to control the network congestion through marking/dropping packets which are used as congestion feedback in traffic sources to balance their flow rate. However, stabilizing queuing delay and maximizing link utilization have been considered as the main control objectives, especially in media dominated networks. Usually, most of the AQM algorithms are designed for a nominal operating point. However, time-varying nature of network parameters frequently violates their robustness bounds. In this paper, a self-tuning compensated PID controller is proposed to address the time-varying nature of network conditions caused by parameter variations and unresponsive connections.... 

    Direct-DMC for AQM computational complexity reduction in TCP/IP networks

    , Article International Conference on Control, Automation and Systems, ICCAS 2007, Seoul, 17 October 2007 through 20 October 2007 ; December , 2007 , Pages 1270-1273 ; 8995003871 (ISBN); 9788995003879 (ISBN) Ostadabbas, S ; Haeri, M ; Sharif University of Technology
    2007
    Abstract
    Active queue management (AQM) mechanisms are designed to provide better support for end-to-end congestion control mechanisms of transmission control protocol (TCP) in TCP/IP networks. This paper introduces Direct Dynamic Matrix Control (D-DMC) as a new AQM method in dynamic TCP networks. Ability of the controller in handling system delay along with its simplicity and low computational loads makes D-DMC a privileged AQM method in high speed networks. The controller is designed based on a small signal linearized fluid-flow model of TCP/AQM networks. The computational complexity analysis as well as the MATLAB simulation results shows the out-performance of the developed controller for both... 

    Predictive functional control for active queue management in congested TCP/IP networks

    , Article ISA Transactions ; Volume 48, Issue 1 , 2009 , Pages 107-121 ; 00190578 (ISSN) Bigdeli, N ; Haeri, M ; Sharif University of Technology
    2009
    Abstract
    Predictive functional control (PFC) as a new active queue management (AQM) method in dynamic TCP networks supporting explicit congestion notification (ECN) is proposed. The ability of the controller in handling system delay along with its simplicity and low computational load makes PFC a privileged AQM method in the high speed networks. Besides, considering the disturbance term (which represents model/process mismatches, external disturbances, and existing noise) in the control formulation adds some level of robustness into the PFC-AQM controller. This is an important and desired property in the control of dynamically-varying computer networks. In this paper, the controller is designed based...