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This paper addresses the design of anti-windup gains for obtaining stability for linear systems with discrete time varying delay and saturating inputs delay. Considering that a dynamic output feedback has been designed to stabilize the AQM system (without saturation), a method is proposed for designing an anti-windup gain which relates the saturation of the queue when congestion, which is inevitable...
The purpose of this paper is to design a congestion controller for Networks TCP/IP Routers, while the available link bandwidth is modeled as a time-variant disturbance. Considering the new uncertain TCP flow model, a memoryless H∞ robust controller is designed to guarantee the stability and performance under time-varying network conditions. The controller parameters are obtained through standard linear...
This paper shows how control techniques, such as PID or generalized predictive control, can improve the performance of TCP/IP networks when dealing with congestion. Drop tail, or more sophisticated AQM techniques such as RED, perform worse than process control techniques. A comparison between the different methods in different working scenarios is analyzed. Two different GPC controllers are evaluated...
Congestion is a problem in real networks. Users do not want to lose information and data should be delivered as fast and reliably as possible. This is really difficult to achieve. Moreover, networks work in changing environments: number of users, type of traffic, delays in transmission, etc. So this paper presents how to design PID controllers that take network changes into account. Non-linear simulations...
The problem of robust H∞ filtering for uncertain two-dimensional (2-D) continuous systems described by the Roesser state-space model is investigated when the parameter uncertainties are polytopic. A sufficient linear matrix inequality (LMI) condition for the existence of a 2-D continuous filter such that, for all admissible uncertainties, the error system is asymptotically stable, and the H∞ norm...
Searching for examples to encourage and motivate students in a subject is not a trivial task. Future Computer Science and Telecommunications Engineers tend to look at Automatic Control reluctantly. They do not relate their working life to it. But, if we blend examples from two areas: telecommunications and control, maybe we can change their minds. These engineers work with web servers: systems that...
This paper presents the design and simulation of a launch vehicle and its guidance, navigation and control subsystems. This process requires the development of a mathematic model, an attitude control system and trajectory optimization. The Ariane 5 ECA is proposed here as the launch vehicle, where the target is a geostationary transfer orbit. This procedure is, however, valid for any other launch...
Internet users rely on the good capabilities of TCP/IP networks for dealing with congestion. The network delay and the number of users change constantly, which might lead to transmission problems. Usually, they are handled following algorithms such as drop tail or random early detection (RED). In recent years, feedback control techniques are providing practical solutions for this problem. In this...
This paper investigates power control algorithms for wireless networks. In particular, it is shown how the most frequently used algorithm for distributed on-line power control (the Foschini-Miljanic algorithm) can be studied using tools from Positive Systems theory. Thus, the stability of the algorithm in the presence of the inherent time-varying delays is proved, and the derivation of bounds on the...
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