L. De Vito

One-Way Delay Measurement: State of the Art

Accurate OWD (one-way delay) measurement has a relevant role in network performance estimation and consequently in application design. In order to estimate OWD accurately it is essential to consider some parameters which influence the measure, such as operating system (OS) loaded on the PC, the treads, and the PC synchronization in the network. Due to the large research interest towards synchronization aspects, the authors have chosen to consider this parameter first. For this reason, three synchronization methods based on NTP (network time protocol), on GPS (global positioning system), and on IEEE 1588 standard are described and compared showing the advantages and disadvantages of the analyzed methods

A Histogram-Based Segmentation Method for Wideband Spectrum Sensing in Cognitive Radios

This paper presents a new method for automatic radio spectrum segmentation. Spectrum segmentation serves as a first step to identify the subbands that are in use at a certain time, when a wide portion of the spectrum is observed. The proposed method, based on the evaluation of the histogram of the power spectral density of the received signal, is designed for obtaining a low processing complexity and to be implemented in a measurement instrument or a cognitive radio receiver. The proposed method is validated on emulated signals, and the results show good accuracy of the subband boundary estimation and a processing complexity much lower than the other segmentation methods.

Prototype of an Automatic Digital Modulation Classifier Embedded in a Real-Time Spectrum Analyzer

This paper presents a prototype of an automatic digital modulation classifier based on a real-time spectrum analyzer (RTSA) architecture. The modulation classifier is suitable for efficient spectrum monitoring to identify the signals present in a certain frequency band, without the need of knowing any parameter about them. The realized prototype is able to recognize classical single-carrier modulations such as M-ary phase-shift keying (PSK), M-ary frequency-shift keying (FSK), M-ary amplitude-shift keying (ASK), and M-ary quadrature amplitude modulation (QAM), as well as orthogonal frequency-division multiplexing (OFDM) modulations such as the discrete multitone (DMT). To evaluate the performance of the prototype, several experiments with actual signals have been carried out in different operating conditions by varying the values of both the main modulation parameters and the signal-to-noise ratio.

An Improved Method for the Automatic Digital Modulation Classification

In this paper, a new method for the automatic modulation classification of an unknown signal, working without any knowledge about the modulation parameters, is proposed. The method has been developed in two different versions, such that it can be implemented on both waveform digitizers and vector signal analyzers. The developed method is able to recognize classical single carrier modulations such as M-ary phase-shift keying (PSK), M-ary frequency shift keying (FSK), M-ary amplitude shift keying (ASK), and M-ary quadrature amplitude modulation (QAM), as well as orthogonal drequency division multiplexing modulations (OFDM) such as the discrete multitone (DMT). Both the versions of the new developed method are able to work with limited-bandwidth signals, too. After the identification of the modulation type, the method automatically estimates some parameters characterizing the modulation. In order to evaluate the method performance, several experimental tests, with simulated and actual signals, have been carried out in different operating conditions by varying the Signal to Noise Ratio and other parameters characterizing the modulation, such as the carrier frequency and the symbol rate.

A wireless-based home rehabilitation system for monitoring 3D movements

This paper deals with a home rehabilitation system, based on wireless motion sensors, for assisting therapists in assessing recovery of patients with motor dysfunctions. Measurements in home rehabilitation may complement the subjective perception of therapist with objective observations that lead to quantitative evaluation. The goal of this work is to discuss design and implementation of a complete system capable of bringing a real-time 3D reconstruction of human posture to therapists desk, starting from exercises performed at patients house. Attention has been paid to reducing costs and clutter of home-side equipments as much as possible.

Validation of a home rehabilitation system for range of motion measurements of limb functions

Home rehabilitation systems have already made their way into widely accepted medical practices, and their further diffusion will help limit healthcare-related costs and improve treatment conditions. For a therapy to successfully rely on a rehabilitation system, this should provide support that can be proven to meet treatment-specific purposes. This work deals with the validation of a home rehabilitation system designed to assist therapists in limb motor dysfunction treatment by providing joint angle measurements. The system under test has been compared with two commercial systems, commonly used in rehabilitation laboratories.

An Improved ADC Error Correction Scheme Based on a Bayesian Approach

The paper presents an improved method for the ADC nonlinearity correction based on a Bayesian filtering approach. In particular, the dependence of the previous method version on the statistic characterization of the input signal has been removed. The proposed improvement has been validated in simulation using behavioural models provided by an ADC producer and on actual ADCs

Real Time Spectrum Analyzer Including an Automatic Digital Modulation Classifier

In this paper, a new instrument for analyzing and characterizing an unknown signal without any a priori parameter knowledge is proposed. This new instrument joins the characteristics of a real time spectrum analyzer (RTSA) with those of an automatic modulation classifier. The modulation classifier is able to recognize classical single carrier modulations such as M-ary phase-shift keying (PSK), M-ary frequency shift keying (FSK), M-ary amplitude shift keying (ASK), and M-ary quadrature amplitude modulation (QAM), as well as orthogonal frequency division multiplexing modulations (OFDM) such as the discrete MultiTone (DMT). After the identification of the modulation type, the classifier automatically estimates some parameters characterizing the modulation. In order to evaluate the performance of the new instrument, several experimental tests, with actual signals, have been carried out in different operating conditions that are particularly critical by varying both the values of the signal to noise ratio and the main parameters of each identifiable modulation.

Session Initiation Protocol Automatic Debugger

This paper aims to propose a session initiation protocol (SIP) automatic debugger tool. It is a software instrument that will be used to verify the compliance of voice over Internet protocol (VoIP) devices, such as soft phones and VoIP gateways to the SIP specifications, and to test the interoperability of VoIP equipment produced by different manufacturers. Different tools are available on the market to conduct a compliance and interoperability validation phase. However, they often have features limited to packet capturing and decoding, or they are simulation tools that often require a complex developing phase to define the behavior of each test. The proposed tool, instead, can be inserted into an SIP network and is capable of observing and analyzing, in an automatic way, the communication steps. It operates by executing three subsequent phases. In the first phase, the SIP messages flowing in the network are captured. Then, a second phase is in charge of grouping SIP messages into transactions and dialog. Finally, a third phase operates by comparing the message flow with a set of predefined rules. Rules have been classified in two groups. Rules belonging to the first group, called static rules, have been obtained by the direct analysis of SIP specifications. Rules belonging to the second group, called dynamic rules, have been obtained by experience with SIP compliance and interoperability testing (with the support of SIP testing experts). When verification of some rules fails, an output is reported by indicating the rule that failed and a list of possible fault causes. The tool has been validated in a laboratory network in different scenarios. Some sample test cases, which have been extracted by these scenarios and show the capability of the SIP automatic debugger tool in finding compliance and interoperability faults, are also presented in this paper.

Estimating the Uncertainty in the Frequency Domain Characterization of Digitizing Waveform Recorders

New propagation formulas for the uncertainty evaluation for the characterization of digitizing waveform recorders are proposed in this paper. The frequency domain figures of merit, as defined in IEEE Std. 1057, have been considered to present useful addenda to the standard. The proposed formulas have been validated on simulated and actual signals.