Giada Giorgi

Performance analysis of Kalman filter-based clock synchronization in IEEE 1588 networks

This paper analyzes the effects on synchronization performances of the accuracy of skew and offset estimates, the short and long-term stability of the unregulated clock, the rate at which timing information is exchanged within the network. The work makes use of a simulated clock based on the state-variable model, for which realistic parameters are obtained from experimental measurements of Allan variance plots for different kinds of clocks.

Investigating WirelessHART coexistence issues through a specifically designed simulator

In this paper, the WirelessHART communication scheme is investigated. The protocol is at first described, in order to underline the key aspects of its design; then, a simulation tool is presented: it enables analysis that accounts for both protocol and physical layers issues. In particular, interference effects on protocol choices can be easily analyzed. The experimental results, obtained from simulations, highlight improvements of WirelessHART with respect to IEEE 802.15.4 standard, concerning the Packet Error Ratio (PER) degradation of interfering networks.

Detection of Anomalous Behaviors in Networks from Traffic Measurements

Analysis and monitoring of traffic measurements can provide a useful tool for diagnostics, troubleshooting, and performance analysis in networks. This paper presents a method for traffic analysis based on the theory of extreme values. Numerical time series obtained from traffic measurements are processed to compute statistical indicators and analyze them to detect significant local features, which may point to some critical network behavior.

Modeling and Simulation Analysis of PTP Clock Servo

In the paper we present a behavioral simulation of PTP synchronization, based on the OMNeT++ simulator. Node, link and traffic source behavior are represented by statistical source and flow models. This approach, which differs from most approaches to PTP analysis, allows to focus on fundamental aspects of analysis and can be useful to assess the suitability of PTP synchronization in relation to network architecture and operating conditions, as well as for the optimization of clock servo design.

On the Analysis of Communication and Computer Networks by Traffic Flow Measurements

This paper investigates the potential contributions of traffic flow measurements in monitoring and network diagnostics. The basic idea is that information of diagnostic relevance may be obtained from the detection of local anomalies in a traffic trace. For this purpose, the paper introduces a novel approach in the analysis of aggregate traffic, which appears to be effective in evidencing potential flow anomalies. Key word ? Network measurement, packet networks, flow rate, anomaly detection.

A case for IEEE Std. 1451 in smart microgrid environments

Smart microgrids exploit information and communication technologies to efficiently manage local renewable energy sources and energy storage devices, collectively known as distributed energy resources (DERs). This requires the inclusion of rather sophisticated sensing and/or actuating units within the DER interfaces.

A measurement approach based on micro-doppler maps for human motion analysis and detection

Human motion analysis is a task of increasing importance in several modern application fields, such as in medicine, avionics, security, and disaster recovery. It requires the application of sophisticated measurement techniques based on micro-Doppler effect, human walking modeling, cinematic simulation, image processing and measurements. In this paper, a novel and comprehensive measurement approach is proposed for the detection and analysis of human motion. The approach combines theoretical concepts and tools of micro-Doppler theory, image processing, and human modeling, in a original way. The attention is primarily focused on some measurement issues and implications that, if taken into account, can give an important enhancement to micro-Doppler-based future applications. Some simulation results concerning one specific issue of the measurement approach are finally provided and discussed.

Innovation-based timestamp validation for reliable sensor network synchronization

Sensor networks need a common timescale to be shared among their constituent elements. Accuracy and reliability are key issues in time dissemination, the latter aspect being specifically addressed in several synchronization schemes. In the paper, we present an approach to reliability assessment based on monitoring the innovation of the Kalman filter employed as the local clock servo in a sensor node. The assumed clock model is described by two state variables and its equations are general enough for most typical devices and operating conditions. Results provided demonstrate the capability to detect unreliable time information, thus improving synchronization performances.

A Study of Measurement-Based Traffic Models for Network Diagnostics

In this paper, the measurement and analysis of network flows are taken into account as a methodology for characterization and diagnosis of network behavior. The accuracy of flow models will be discussed, reviewing the basic underlying assumptions. A modeling approach based on multidomain analysis will be proposed, where flow measurements can be complemented by a limited amount of protocol data gathered from packet headers. By the analysis of experimental data, we argue that, in several situations, traffic may be more appropriately modeled by the superposition of multiple flows with different characteristics, which results in better measurements and improved diagnostic possibilities.

Rate-interval curves - A tool for the analysis and monitoring of network traffic

In this paper we propose a method, related to the theory of Network Calculus, for the analysis of aggregate network traffic by means of empirical rate-interval curves obtained from experimental data. The algorithm on which it is based differs from the commonly employed wavelet-based approach, although it retains some of its multiresolution features. We briefly introduce the theoretical aspects, analyze measurement accuracy and present results, obtained both by simulation and by the analysis of real traffic traces, which provide an assessment of the strengths and weaknesses of the proposed method. Rate-interval curve analysis provides very robust and acceptably accurate estimates of the Hurst parameter value and, even in the presence of flow irregularities, results can be proved to be correct as far as scaling properties are concerned. Further analyzes concerning peaks, bursts and similar localized phenomena that may have a significant impact on the performances of a network are allowed by considering maximal rate envelopes, showing the potential of this approach for monitoring applications.