The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper examines the accuracy of the zero-order hold (ZOH) model of the digital pulsewidth modulator (DPWM). The influence of the computational delay on the precision of this equivalent DPWM model is discussed in detail. A compensation method is proposed to compensate the deviation of this DPWM model for accurately calculating the stability region with different computational delay and duty-cycle...
In this paper, a sliding mode learning controller is developed for connection-oriented communication networks. Firstly, a networking system is modelled as discrete-time nth-order dynamic system subject to time-varying delay, the congestion control problem in communication networks is then addressed by adopting a novel sliding mode learning controller. The proposed learning controller not only suppresses...
This paper concerns with the typical problem of disturbance rejection in process control in the presence of time-delays and, possibly, the integrating or unstable dynamics. It is shown how unknown disturbance can be rejected actively in the absence of detailed mathematical model of the process. Disturbance rejection ability and stability are analyzed using the language of frequency response engineers...
Rate control is a big challenge for real-time video streaming on the internet with the needs of low latency, bandwidth-consuming and stable video rate. However, most of the existing Internet congestion control protocols ignore these needs, and some of them use the packet loss event as congestion signal which is deviation especially over error-prone wireless networks. In this paper, we propose a delay-constrained...
Duplex filters in modern base stations are designed as cavity filters, which are expensive and have big dimensions. Thanks to the emerging digital technology and fast digital converters, it is possible to transfer the efforts of designing analog duplex filters into digital numeric algorithms applied to feedback structures, operating on power amplifiers in transmitters. The design of a digital baseband...
Under the constraints of limited bandwidth and exponentially rising user demand, there is a dire need to maximize throughput. Maintaining Quality of Service (QoS) in a communication network demands congestion control with high accuracy. This paper focuses on this challenging task that incorporates design of effective congestion controller to reduce packet loss in cognitive radio networks. Limited...
In this paper, control strategies of a 22 MW / 27 MVA machine test bench using pumpback topology are introduced. The current loop design at extremely low pulse ratios (e.g. 600 Hz carrier frequency / 80 Hz load frequency) is developed. The system stability and dynamic response are analyzed. The challenges for high-power machine control with a sine filter and a transformer connected between the voltage-source-inverter...
This paper presents a hop-by-hop congestion control for highspeed networks. The control policy relies on the data exchange between adjacent nodes of the network (nearest-neighbour interaction). The novelty of this paper consists in the extensive use of Internal Model Control (IMC) to set the rates of the traffic flows. As a result, the proposed congestion control provides upper-bounds of the queue...
We consider the design of transport protocols for background transfers with the aim of reducing the download delays of interactive (non-background) flows which share the same links. We demonstrate that Lower than Best Effort (LBE) protocols suffer from bandwidth starvation, a fact which not only creates adoption disincentives but can have a harmful effect on the interactive flows as well. Instead...
In this paper, four current control strategies for voltage source PWM inverters with LCL-filter at extreme low pulse ratios (e.g. 80 Hz load frequency/600 Hz carrier frequency) are investigated. The system is a medium-voltage variable frequency drive (VFD) application with the power rating over 20 MW. The benefits and drawbacks of each scheme are summarized to provide a guideline for the current control...
In this paper, we propose a cognitive protocol that involves cooperation between the primary and secondary users. In addition to its own queue, the secondary user (SU) has a queue to store, and then relay, the undelivered primary packets. When the primary queue is nonempty, the SU remains idle and attempts to decode the primary packet. When the primary queue is empty, the SU splits the total channel...
Many cyber-physical systems comprise several control applications implemented on a shared platform, for which stability is a fundamental requirement. This is as opposed to the classical hard real-time systems where often the criterion is meeting the deadline. However, the stability of control applications depends on not only the delay experienced, but also the jitter. Therefore, the notion of deadline...
XCP is one of the most commonly used protocols in modern congestion control implementations. XCP can provide the available transmission rate to applications. It is well known fact that one of the issues of XCP is that the time-delay of its traditional implementation (TR-XCP) is twice the time-delay of its flow model. This leads to unstable behaviors when controlling the congestion in networks with...
We have designed and investigated a new congestion control scheme, called the OFEX (Optimal and Fully EXplicit) controller. Different from the existing relatively explicit controllers, this new scheme is able to provide not only optimal bandwidth allocation but also fully explicit congestion signal to sources. It overcomes the drawback of the relatively explicit controllers that “bias” the multi-bottlenecked...
EMKC is an explicit congestion control algorithm which is designed for high bandwidth delay product (BDP) networks. Although delay-independence is an appealing characteristic, the EMKC system developed in exhibits undesirable equilibrium properties and slow fairness convergence behavior. To overcome these drawbacks, we propose a new method called AEMKC (Advanced Exponential Max-Min Kelly Control)...
In the distant-downstream control of irrigation channels, the interactions between pools and the internal time-delay for water to travel from upstream to downstream, impose limitations on global performance, i.e. there exist propagation of water level errors and amplification of flows over gates in the upstream direction. This paper analyses these coupling properties for a string of identical pools,...
EMKC is an explicit congestion control algorithm which is designed for high bandwidth delay product (BDP) networks. Although delay-independence is an appealing characteristic, the EMKC system developed in exhibits undesirable equilibrium properties and slow fairness convergence behavior. To overcome these drawbacks, we propose a new method called MEMKC (Modified Exponential Max-Min Kelly Control)...
This paper addresses a practical networked based control application. A Profibus DP is considered in order to coordinate a triangular maglev platform. The control of this magnetic levitation process is a complicated system from an control engineering point of view due to its unstable, non-minimum phase and non-linear nature; the difficulty is growing up because the bandwidth limitation and some other...
In contrast to the existing approaches, the design is based on a discrete-time model with loop delay. In addition to the closed-loop stability, this method deals with the practical considerations: ripple swing, reference spur, and stability margin. One advantage of the proposed method is that it allows one to specify the Alter poles in advance. The loop Alter design problem is formulated as an H-infinity...
Traditional congestion control algorithms exhibit low convergence speed to equilibrium in high BDP (Bandwidth Delay Product) networks. The Fast Max-Min Kelly Control (FMKC) is a new and promising protocol that performs well especially in fairness convergence speed. FMKC utilizes packet loss to switch temporarily into a fairing mode and thereby improve the fairness convergence speed. In this paper,...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.