S. Van den Berghe

Efficient mode-matching analysis of discontinuities in finite planar substrates using perfectly matched layers

A new method to determine the reflection of substrate modes in finite substrate planar circuits is proposed. The perfectly matched layer (PML) concept is used to transform the open problem into a closed one. The discrete set of substrate, evanescent, and Berenger modes of the resulting anisotropic waveguides are then used in a mode-matching scheme to deduce the scattering coefficients of the substrate modes for oblique incidence on the edge of the substrate. We show results for single- and double-layered substrates and compare with finite-difference time-domain (FDTD) results. The combined perfectly matched layer (PML) mode-matching technique turns out to be very efficient.

Accurate modeling of thin conducting layers in FDTD

In recent papers the surface impedance condition is proposed to incorporate the effect of high conductivity of a material. This condition only takes the reflection at materials into account; the transmission through very thin layers is not considered. In this work, we introduce a similar approach to model both reflection and transmission when confronted with a thin layer of good, but not perfectly, conducting material.

Design for a Generic Knowledge Base for Autonomic QoE Optimization in Multimedia Access Networks

The management of access networks to guarantee the Quality of Experience for multiplay services, is complicated by the heterogeneity in service specifics and home network configurations. The appropriate action to restore the QoE is highly dependent on the type of service, the affected user, etc. This requires an almost per-user and per-service management. Through autonomous reasoning, the required QoE restorative actions for underperforming services can be determined in a scalable way. This reasoning process needs a solid knowledge base, containing information about the network, the services and the QoE restorative actions that can be undertaken. This article gives an overview of these requirements and presents an OWL/SWRL based knowledge base that can be used in an autonomous QoE management architecture for the access network. Besides storing all information, the proposed knowledge base will autonomously deduce new information. This new information can be used to raise alarms to higher layers in the architecture or to autonomously propose QoE restorative actions for underperforming services.

Design of an Autonomic QoE Reasoner for Improving Access Network Performance

The access network has become an infrastructure for delivery of multimedia services, such as broadcast TV, voice over IP or video conferencing, to residential users . Compared to more traditional IP services such as e-mail, users demand a higher quality of experience (QoE) for these new services. To guarantee the quality of service (QoS), access network providers have deployed several service enablers, such as video on demand proxies. These techniques are only focused on the part between the service edge router and the access node, while the access network provider has only a limited view and impact on the home network environment. The QoE management in the home network is even more complicated by the wide range of user devices and the various home network configurations, containing wireless interfaces and home multimedia servers. This paper explores the architectural design of an autonomic intelligence component on the access node that determines required QoE enhancing actions, such as adjusting the video bit rate, by taking into account the specifics of the home network and the requested services. The viability of an analytical, fuzzy logic and neural network approach to implement an intelligent, autonomic reasoner is discussed, and experimental results are presented.

Power plane resonances as a source of delta-I noise and the influence of decoupling capacitors

This contribution presents a study of the influence of power planes resonances on the delta-I noise. Noise generated at one point in a system can be transported to a distant point. This phenomenon is studied using the FDTD-technique and a transfer impedance is introduced to quantify the results. To shield sensitive ICs, capacitive decoupling can be used. The influence of such capacitive shielding is discussed. Analytical approximations are given together with more details on the influence of the different parameters.

Efficient FDTD S-parameter calculation of microwave structures with TEM ports

We have presented an accurate and efficient method for S-parameter calculation. The method uses a variation on the total field-scattered field formalism, the modes are injected and extracted at the interface between the total field and the error field regions. As such the propagated energy never actually reaches the boundary conditions, so these conditions can be less stringent, and should require less resources. Furthermore, the mode distributions are used to excite the structure and to calculate the amplitude of the propagating mode. This allows us to place both the excitation mechanism and the port regions very close to the simulated structure, again saving resources, as well as preserving the accuracy of the method. However, due to the dispersion of non-TEM modes, this method can only be used if the mode of interest is TEM. Our method has been compared with the method of moments approach and the results are almost identical.

SONAR: a platform for flexible DiffServ/MPLS traffic engineering

A major opportunity for IP network operators to increase the revenue stream generated by their network is a closer and faster integration of services into the IP broadband network. However, with this integration come responsibilities concerning the quality, availability and continuity of these services, which are much harder to fulfil than the requirements for the current IP data traffic. SONAR (service-oriented networking using adaptive resource control) is a network management and operations platform designed to drive a DiffServ/MPLS network so that these responsibilities can be met. In this paper we discuss and evaluate the architecture and algorithms that are the basis for this platform. The architecture decomposes the network management problem in two components: a centralised path computation and a distributed tunnel management. Finally this hybrid on line/off line adaptive traffic engineering approach is evaluated in an modified NS-2 simulator environment.

Integrating policy-based access management and adaptive traffic engineering for QoS deployment

In this paper, we describe our experiences of designing a platform that integrates distributed policy-based access control and trust management technologies with a developed QoS-aware network management platform. The main goal of this study is to demonstrate how the application of policy-based decision processes can help to deploy the platform in a scalable way offering adaptive services with enriching features such as flexible rule-based service definitions and roaming.

Distributed policy-based management of measurement-based traffic engineering: design and implementation

This article discusses an architecture using monitoring feedback as an assisting factor for delivering QoS on packet-based networks. The handling of this feedback is done in an automated way, through the use of a policy-based management architecture. For this, a formal model for describing data plane and measurement objects was translated into an XML-based configuration language. On top of this, a proof-of-concept management architecture was developed and evaluated, using both a modified network simulator and enhanced Linux prototype routers.

ESD Entrypoints: Coaxial Cables Vs. Shielding Apertures

We study the effect of electrostatic discharge (ESD) on coaxial cable connections between different systems. These cables may be a very efficient entrypoint for unwanted ESD signals. The effect of an electrostatic discharge on the cable shielding is compared to the effect of indirect and direct ESD on the system shielding itself. To study the effect of the various pathways of ESD we use an FDTD algorithm. The disturbance induced in the inside of the cable is evaluated by using the transfer impedance of the cable shield.We study the effect of electrostatic discharge (ESD) on coaxial cable connections between different systems. These cables may be a very efficient entrypoint for unwanted ESD signals. The effect of an electrostatic discharge on the cable shielding is compared to the effect of indirect and direct ESD on the system shielding itself. To study the effect of the various pathways of ESD we use an FDTD algorithm. The disturbance induced in the inside of the cable is evaluated by using the transfer impedance of the cable shield.