An Active Queue Management (AQM) robust control strategy for Traffic Control Protocol (TCP) data transfer is proposed. To this purpose, the TCP behaviour is first approximated by a second-order model with delayed input obtained from the linearization of an efficient and commonly used nonlinear fluid-based model. The adopted feedback control structure uses a fractional-order PI controller. To ensure the desired robustness, the parameter regions where such a controller guarantees a given modulus margin (inverse of the H∞ norm of the sensitivity function) are derived. An example commonly used in the literature is worked out to show that the suggested graphically-based design technique is simple to apply while it limits the effects of disturbances and of the unmodelled dynamics.
Fractional order PI controllers for TCP packet flow ensuring given modulus margins
Viaro U.
2014-01-01
Abstract
An Active Queue Management (AQM) robust control strategy for Traffic Control Protocol (TCP) data transfer is proposed. To this purpose, the TCP behaviour is first approximated by a second-order model with delayed input obtained from the linearization of an efficient and commonly used nonlinear fluid-based model. The adopted feedback control structure uses a fractional-order PI controller. To ensure the desired robustness, the parameter regions where such a controller guarantees a given modulus margin (inverse of the H∞ norm of the sensitivity function) are derived. An example commonly used in the literature is worked out to show that the suggested graphically-based design technique is simple to apply while it limits the effects of disturbances and of the unmodelled dynamics.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
