Nuova ricerca

Fabrizio PANCALDI

Ricercatore Universitario
Dipartimento di Scienze e Metodi dell'Ingegneria

Home | Curriculum(pdf) | Didattica |


Pubblicazioni

- SYSTEM FOR DETECTING THE POSITION OF AIRCRAFTS AND/OR MOTOR VEHICLES ON AIRPORT RUNWAYS AND TRAFFIC WAYS [Brevetto]
G., Cannistra'; Pancaldi, Fabrizio
abstract

System for detecting the position of aircrafts and/or motor vehicles in the airport runways and traffic ways, along which there are installed lighting signallers (2), comprising: radar devices (4) installed in at least a portion of said lighting signallers (2). Each radar device (4) is intended to localize the position of an aircraft (3) and/or motor vehicle situated in a section of runway (1) or traffic way, which is near the corresponding lighting signaller (2), where the radar device (4) itself is installed; and means for transmitting the data processed by each radar device (4) to a remote unit, in order to detect the position of the aircrafts (3) and/or motor vehicles. According to a variant of the invention, in place of the radar devices (4), other position detecting devices are employed, each comprising an accelerometer (41) or a thermal sensor.

- poligono di tiro [Brevetto]
Pancaldi, Fabrizio; Rovati, Luigi
abstract

L’invenzione descrive un poligono di tiro comprendenteuno schermo (5), su cui vengono proiettate immagini dibersagli (9) e su cui tiratori sparano con armi diqualsiasi natura, mezzi emettitori (17) di fasci diradiazioni diretti verso lo schermo (5).Un’unità di controllo (30) si occupa di rilevare un tiroe di calcolare se è stato realizzato un centro. [FIG. 1]

2024 - Pre-processing techniques to enhance the classification of lung sounds based on deep learning [Articolo su rivista]
Fava, Alessandra; Dianat, Behnood; Bertacchini, Alessandro; Manfredi, Andreina; Sebastiani, Marco; Modena, Marco; Pancaldi, Fabrizio
abstract

2023 - Classification of pulmonary sounds through deep learning for the diagnosis of interstitial lung diseases secondary to connective tissue diseases [Articolo su rivista]
Dianat, Behnood; La Torraca, Paolo; Manfredi, Andreina; Cassone, Giulia; Vacchi, Caterina; Sebastiani, Marco; Pancaldi, Fabrizio
abstract

2023 - Impact of noise model on the performance of algorithms for fault diagnosis in rolling bearings [Articolo su rivista]
Pancaldi, F; Dibiase, L; Cocconcelli, M
abstract

Condition monitoring of rolling bearings is attracting much interest since most of the production slowdowns depends on the damaging of these components. Several algorithms for fault detection have appeared in the technical literature in the last decade. In most cases, performance is assessed over both synthetic and experimental data. Unfortunately, the computer simulations adopt signal models that are trivial and are not able to predict the actual performance on the field. In this work we propose a framework suitable to fairly, quantitatively and objectively compare different algorithms for fault detection in rolling bearings. The vibration signal is obtained through computer simulations. The signal entailed by the damage is generated through the model at "impact-delay-line" already available in the technical literature. The machine noise is generated as a wideband component with the possible superposition of narrowband components. The wideband component has been modeled as additive white Gaussian noise, additive white noise drawn from an alpha-stable distribution and additive noise stemming from an autoregressive process. Narrowband components are modeled through trains of Gaussian pulses. The performance of three well known algorithms for fault detection are compared in terms of capability in identifying the theoretical cyclic frequencies related to a damage. In these scenarios the behavior of fault detectors are definitely far from that predicted by classical wideband noise models like, for instance, additive white Gaussian noise.

2023 - On the performance comparison of diagnostic techniques in machine monitoring [Articolo su rivista]
Pancaldi, F.; Rubini, R.; Cocconcelli, M.
abstract

Predictive maintenance can save a lot of efforts in modern industry and condition monitoring is attracting a lot of attention accordingly. New algorithms for fault detection appear frequently in the technical literature, however an objective, quantitative and widely accepted approach to performance comparison is still lacking. In this paper, we propose a new method leading to a fair and reproducible performance assessment. The proposed solution is based on vibrational analysis and consists of searching and detecting the theoretical cyclic frequencies that appear as a specific "signature" of a fault. Each algorithm for condition monitoring relies on a metric, then the main idea is to quantitatively characterize the peaks of the metric emerging from the machine noise. We think that the wide adoption of the proposed approach could significantly foster the research in the fields of condition monitoring and predictive maintenance.

2022 - Identification of Soft Tissue-Mimicking Materials and Application in the Characterization of Sensors for Lung Sounds [Articolo su rivista]
Torraca, P. L.; Ausiello, L.; Zucchi, G.; Farina, A.; Pancaldi, F.
abstract

Early diagnosis of pulmonary implications is fundamental for the treatment of several diseases, such as idiopathic pulmonary fibrosis, rheumatoid arthritis, connective tissue diseases and interstitial pneumonia secondary to COVID-19 among the many. Recent studies prove that a wide class of pulmonary diseases can be early detected by auscultation and suitably developed algorithms for the analysis of lung sounds. Indeed, the technical characteristics of sensors have an impact on the quality of the acquired lung sounds. The availability of a fair and quantitative approach to sensors' comparison is a prerequisite for the development of new diagnostic tools. In this work the problem of a fair comparison between sensors for lung sounds is decoupled into two steps. The first part of this study is devoted to the identification of a synthetic material capable of mimicking the acoustic behavior of human soft tissues; this material is then adopted as a reference. In the second part, the standard skin is exploited to quantitatively compare several types of sensors in terms of noise floor and sensitivity. The proposed methodology leads to reproducible results and allows to consider sensors of different nature, e.g. laryngophone, electret microphone, digital MEMS microphone, mechanical phonendoscope and electronic phonendoscope. Finally, the experimental results are interpreted under the new perspective of equivalent sensitivity and some important guidelines for the design of new sensors are provided. These guidelines could represent the starting point for improving the devices for acquisition of lung sounds.

2022 - VECTOR: An algorithm for the detection of COVID-19 pneumonia from velcro-like lung sounds [Articolo su rivista]
Pancaldi, F.; Pezzuto, G. S.; Cassone, G.; Morelli, M.; Manfredi, A.; D'Arienzo, M.; Vacchi, C.; Savorani, F.; Vinci, G.; Barsotti, F.; Mascia, M. T.; Salvarani, C.; Sebastiani, M.
abstract

The coronavirus disease 2019 (COVID-19) has severely stressed the sanitary systems of all countries in the world. One of the main issues that physicians are called to tackle is represented by the monitoring of pauci-symptomatic COVID-19 patients at home and, generally speaking, everyone the access to the hospital might or should be severely reduced. Indeed, the early detection of interstitial pneumonia is particularly relevant for the survival of these patients. Recent studies on rheumatoid arthritis and interstitial lung diseases have shown that pathological pulmonary sounds can be automatically detected by suitably developed algorithms. The scope of this preliminary work consists of proving that the pathological lung sounds evidenced in patients affected by COVID-19 pneumonia can be automatically detected as well by the same class of algorithms. In particular the software VECTOR, suitably devised for interstitial lung diseases, has been employed to process the lung sounds of 28 patient recorded in the emergency room at the university hospital of Modena (Italy) during December 2020. The performance of VECTOR has been compared with diagnostic techniques based on imaging, namely lung ultrasound, chest X-ray and high resolution computed tomography, which have been assumed as ground truth. The results have evidenced a surprising overall diagnostic accuracy of 75% even if the staff of the emergency room has not been suitably trained for lung auscultation and the parameters of the software have not been optimized to detect interstitial pneumonia. These results pave the way to a new approach for monitoring the pulmonary implication in pauci-symptomatic COVID-19 patients.

2021 - A simple multiparametric analysis to guide, compare and optimize the design of 'lensless' LED illuminators [Relazione in Atti di Convegno]
Cattini, S.; Pancaldi, F.; Bertacchini, A.; Parmeggiani, A.
abstract

LED lighting is becoming increasingly pervasive in many areas ranging from ambient lighting, up to applications such as microscope illumination, UV-LED curing and, UV disinfection for air, surfaces, and water. Irradiance uniformity is often a fundamental parameter for guiding the design, comparison, and optimization of the illuminator. To this end, many methods and procedures have been proposed to guide the arrangement of the LED sources, as well as to guide the design of ad-hoc lenses. Nevertheless, there are many applications in which it is important to be able to consider other aspects as well as the uniformity of the irradiance. For this purpose, we propose both a method that allows calculating the irradiance generated by the used LED sources and, performance indicators for guiding the design and comparing different optical layouts.

2021 - A statistical approach for modeling individual vertical walking forces [Articolo su rivista]
Pancaldi, F.; Bassoli, E.; Milani, M.; Vincenzi, L.
abstract

This paper proposes a statistical approach for modeling vertical walking forces induced by single pedestrians. To account for the random nature of human walking, the individual vertical walking force is modeled as a series of steps and the gait parameters are assumed to vary at each step. Walking parameters are statistically calibrated with respect to the results of experimental tests performed with a force plate system. Results showed that the walking parameters change during walking and are correlated with each other. The force model proposed in this paper is a step-by-step model based on the description of the multivariate distribution of the walking features through a Gaussian Mixture model. The performance of the proposed model is compared to that of a simplified load model and of two force models proposed in the literature in a numerical case study. Results demonstrate the importance of an accurate modeling of both the single step force and the variability of the individual walking force.

2021 - Usefulness of digital velcro crackles detection in identification of interstitial lung disease in patients with connective tissue diseases [Articolo su rivista]
Manfredi, A.; Cassone, G.; Vacchi, C.; Pancaldi, F.; Casa, G. D.; Cerri, S.; De Pasquale, L.; Luppi, F.; Salvarani, C.; Sebastiani, M.
abstract

Objectives: This study aims to evaluate the diagnostic accuracy of the VECTOR software in patients with connective tissue diseases (CTDs), compared with the reference standard of high-resolution computed tomography (HRCT). Patients and methods: The study included 98 consecutive patients of CTD (24 males, 74 females; median age: 66 years; range, 24 to 85 years) with a recent HRCT. Patients were evaluated in a blindly manner by VECTOR and the results obtained by the algorithm were compared with the presence of interstitial lung disease (ILD) according to HRCT. Results: Interstitial lung disease was detected in 42.8% of subjects. VECTOR correctly classified 81/98 patients, with a diagnostic accuracy of 82.6%; sensitivity and specificity were 88.1% and 78.6%, respectively. Only 5/42 patients with ILD were not correctly classified by VECTOR, while false positive cases were 21.4%. No significant differences were observed according to the radiologic pattern of ILD. Conclusion: VECTOR showed high sensitivity, specificity and diagnostic accuracy, allowing selecting patients to be investigated with HRCT. The relatively high frequency rate of false positive results is acceptable if compared with the lack of effective screening methods for this complication of CTDs.

2020 - Erratum: Acute exacerbation of interstitial lung diseases secondary to systemic rheumatic diseases: A prospective study and review of the literature (Journal of Thoracic Disease (2019) 11 (1621-1628) DOI: 10.21037/jtd.2019.03.28) [Articolo su rivista]
Manfredi, A.; Sebastiani, M.; Cerri, S.; Vacchi, C.; Tonelli, R.; Della Casa, G.; Cassone, G.; Spinella, A.; Pancaldi, F.; Luppi, F.; Salvarani, C.
abstract

In the article that appeared on Page 1621-1628, Vol 11, No 4 (April 2019) Issue of the Journal of Thoracic Disease (1), the given and family names of author “Fabrizio Pancaldi” was incorrectly published in the original. The author's name should be corrected as Fabrizio Pancaldi, instead of Pancaldi Fabrizio. The authors regret the error.

2020 - INTERSTITIAL LUNG DISEASE RELATED TO RHEUMATOID ARTHRITIS. WHAT DO WE DON’T KNOW? THE LIRA STUDY (LUNG INVOLVEMENT IN RHEUMATOID ARTHRITIS) [Articolo su rivista]
Sebastiani, M.; Vacchi, C.; Cassone, G.; Salvarani, C.; Sandri, G.; Atzeni, F.; Biggioggero, M.; Carriero, A.; Erre, G. L.; Fedele, A. L.; Furini, F.; Tomietto, P.; Venerito, V.; Atienza-Mateo, B.; Della Casa, G.; Cerri, S.; Palermo, A.; Galli, E.; Pancaldi, F.; González-Gay, M. A.; Manfredi on behalf of LIRA Study Group, A.
abstract

Background: Interstitial lung disease (ILD) is one of the more frequent and potentially severe extra-articular manifestation of rheumatoid arthritis (RA). ILD significantly decreases the survival and quality of life of patients and influences the treatment approach to the patient. Despite its clinical relevance, the prevalence, incidence and survival of RA-ILD is unknown and supposed on the base of retrospective data or registry-based studies. Objectives: For the first time, the Lung Involvement in Rheumatoid Arthritis (LIRA) study aims to investigate epidemiology, features and prognosis of RA-ILD patients in a prospective international multicentre study. Methods: All RA patients referring to the involved centres will be evaluated every six months with a digital stethoscope and a software able to identify velcro crackles with a diagnostic accuracy of 83.9% (VECTOR). In fact, velcro crackles are virtually identified in all stages of fibrosing alveolitis like RA-ILD, and their search is as a simple and reliable method to screening patients to be undergone to high resolution computed tomography (HRCT). For each patient, clinical and serological data are recorded at baseline and every six months; when velcro crackles or other conditions suspicious for ILD, such as cough or dyspnoea, are detected, a HRCT is requested to confirm ILD. Patients with ILD periodically perform pulmonary function tests to monitor lung function evolution. Results: At now, 205 RA patients have been enrolled (female/male 161/44, mean age 64.8±12.9 years, mean disease duration 14.2±8.9 years), anti-citrullinated peptides antibodies (ACPA) and rheumatoid factor (RF) were positive in 77.1% and 78.1%, respectively. The prevalence of ILD was 21% (43 patients). In other 13 patients the HRCT is ongoing; therefore, we could suppose up to a prevalence of 27.3%. Patients with ILD were symptomatic in 53.5% of cases (23 patients), they are more frequently males and were older than patients without ILD (mean age 73.2±7.4 and 62.7±13.2; p<0.0001, female/male ratio 139/23 vs 22/21; p<0.0001) without significant differences regarding disease duration, positivity for ACPA or RF. Conclusion: The prevalence and the incidence of RA-ILD is still not well defined. Preliminary data of our study confirm a prevalence of ILD higher than 20%, patients are asymptomatic in almost the half of cases and more frequently males and elderly. Our study can help to define the clinical history of these patients, the possible association with clinical and serological features and the supposed role of some drugs.

2020 - Time-varying metrics of cyclostationarity for bearing diagnostic [Articolo su rivista]
Pancaldi, F.; Rubini, R.; Cocconcelli, M.
abstract

Ball bearings represent the most adopted solution to support rotating elements. Separated by the cage, the rolling elements are induced by the kinematics of the system to roll and accidentally slip on the rings. In working conditions the continuous contact of the elements leads to a wearing of the bearing surfaces. As a consequence, the early detection of faults represents an issue for modern diagnostic systems. The mathematical model of faulted rolling bearings has been extensively investigated in the last decades and it is widely accepted that a faulted bearing is subject to an unwanted slippery leading to a cyclostationary vibration signal. This paper presents a novel approach to the diagnosis of rolling bearings based on the statistical definition of cyclostationarity. In particular, various metrics have been devised to track the “cyclostationary signature” of the vibration signal and the performance of the proposed algorithms has been assessed through both experimental measurements and synthetic data. Numerical results have shown that the new approach to fault detection is comparable to conventional techniques based on spectral kurtosis, demodulation and spectral correlation, and it can outperform them in some cases; furthermore the simplicity of the proposed algorithms leads to an intrinsic robustness against the mechanical noise typical of practical scenarios.

2019 - AB1157 VALIDATION OF VECTOR (VELCRO CRACKLES DETECTOR) FOR THE DIAGNOSIS OF INTERSTITIAL LUNG DISEASE IN PATIENTS WITH CONNECTIVE TISSUE DISEASES [Abstract in Rivista]
Manfredi, Andreina; Cassone, Giulia; Pancaldi, Fabrizio; Vacchi, Caterina; Cerri, Stefania; Casa, Giovanni Della; Salvarani, Carlo; Sebastiani, Marco
abstract

2019 - Acute exacerbation of interstitial lung diseases secondary to systemic rheumatic diseases: A prospective study and review of the literature [Articolo su rivista]
Manfredi, A.; Sebastiani, M.; Cerri, S.; Vacchi, C.; Tonelli, R.; Casa, G. D.; Cassone, G.; Spinella, A.; Pancaldi, Fabrizio; Luppi, F.; Salvarani, C.
abstract

Acute exacerbation (AE) is a possible manifestation of interstitial lung diseases (ILD) associated to very high mortality. It’s defined as clinically significant respiratory deterioration with evidence of new widespread alveolar abnormalities on computed tomography scan. AE is better described in idiopathic pulmonary fibrosis (IPF) but also reported in ILD secondary to connective tissue diseases (CTD) and vasculitis. The main features and the real clinical impact of this severe complication in these patients are not well defined. Aim of our study was to prospectively investigate the incidence, clinical features and outcome of AE in a population of patients with ILD related to CTD and vasculitis. We consecutively enrolled all patients, with ILD secondary to rheumatic systemic diseases, referring to our multidisciplinary outpatient clinic for rare lung diseases. All patients were followed for at least 12 months (range, 12–36 months). At baseline, all patients underwent to a core set of laboratory investigations and periodically followed; data about demographic, disease onset, clinical, serological and therapeutic features were also recorded. AE occurred in 9/78 patients, with an incidence of 5.77/100 patients/year, and 5/9 patients died because of AE. The baseline value of DLCO was significantly associated to the risk of AE at Cox regression. In patients with ILD related to rheumatic systemic diseases AE can occur with an incidence similar to IPF. Rheumatologists should carefully consider this life-threatening complication as a possible natural course of all patients with ILD secondary to systemic rheumatic disease.

2019 - Comparison of metrics for peaks enhancement in variable speed conditions [Capitolo/Saggio]
Cocconcelli, Marco; Rubini, Riccardo; Pancaldi, Fabrizio; Capdessus, Cécile
abstract

The mathematical model of a faulted ball bearings has been extensively investigated in the last decades. So far, it is widely accepted that a faulted bearing is subject to an unwanted slip in working conditions and this leads to a cyclostationary vibration signal. In literature, various metrics have been devised to track the cyclic frequencies of the vibration signal, based on the statistical definition of cyclostationarity. In variable speed applications, the momentum of the mechanical system and dynamics loads play a fundamental role in the resulting amplitude of the vibration signal. A valuable metric for condition monitoring has to enhance the peaks of vibration signal related to a fault even if the dynamic load is not high. In this paper, five metrics are compared on a benchmark data from a variable speed application. The results indicate time-varying kurtosis (i.d. the moment of the fourth order of the data) as a possible winner.

2019 - Diagnostic accuracy of a velcro sound detector (VECTOR) for interstitial lung disease in rheumatoid arthritis patients: The InSPIRAtE validation study (INterStitial pneumonia in rheumatoid ArThritis with an electronic device) [Articolo su rivista]
Manfredi, A.; Cassone, G.; Cerri, S.; Venerito, V.; Fedele, A. L.; Trevisani, M.; Furini, F.; Addimanda, O.; Pancaldi, F.; Della Casa, G.; D'Amico, R.; Vicini, R.; Sandri, G.; Torricelli, P.; Celentano, I.; Bortoluzzi, A.; Malavolta, N.; Meliconi, R.; Iannone, F.; Gremese, E.; Luppi, F.; Salvarani, C.; Sebastiani, M.
abstract

Background: Interstitial lung disease (ILD) is a severe systemic manifestation of rheumatoid arthritis (RA). High-resolution computed tomography (HRCT) represents the gold standard for the diagnosis of ILD, but its routine use for screening programs is not advisable because of both high cost and X-ray exposure. Velcro crackles at lung auscultation occur very early in the course of interstitial pneumonia, and their detection is an indication for HRCT. Recently, we developed an algorithm (VECTOR) to detect the presence of Velcro crackles in pulmonary sounds and showed good results in a small sample of RA patients. The aim of the present investigation was to validate the diagnostic accuracy of VECTOR in a larger population of RA patients, compared with that of the reference standard of HRCT, from a multicentre study. Methods: To avoid X-ray exposure, we enrolled 137 consecutive RA patients who had recently undergone HRCT. Lung sounds of all patients were recorded in 4 pulmonary fields bilaterally with a commercial electronic stethoscope (ES); subsequently, all HRCT images were blindly evaluated by a radiologist, and audio data were analysed by means of VECTOR. Results: Fifty-nine of 137 patients showed ILD (43.1%). VECTOR correctly classified 115/137 patients, showing a diagnostic accuracy of 83.9% and a sensitivity and specificity of 93.2 and 76.9%, respectively. Conclusions: VECTOR may represent the first validated tool for the screening of RA patients who are suspected for ILD and who should be directed to HRCT for the diagnosis. Moreover, early identification of RA-ILD could contribute to the design of prospective studies aimed at elucidating unclear aspects of the disease.

2018 - "Velcro-type" crackles predict specific radiologic features of fibrotic interstitial lung disease [Articolo su rivista]
Sgalla, Giacomo; Walsh, Simon L. F.; Sverzellati, Nicola; Fletcher, Sophie; Cerri, Stefania; Dimitrov, Borislav; Nikolic, Dragana; Barney, Anna; Pancaldi, Fabrizio; Larcher, Luca; Luppi, Fabrizio; Jones, Mark G.; Davies, Donna; Richeldi, Luca
abstract

Background: "Velcro-type" crackles on chest auscultation are considered a typical acoustic finding of Fibrotic Interstitial Lung Disease (FILD), however whether they may have a role in the early detection of these disorders has been unknown. This study investigated how "Velcro-type" crackles correlate with the presence of distinct patterns of FILD and individual radiologic features of pulmonary fibrosis on High Resolution Computed Tomography (HRCT). Methods: Lung sounds were digitally recorded from subjects immediately prior to undergoing clinically indicated chest HRCT. Audio files were independently assessed by two chest physicians and both full volume and single HRCT sections corresponding to the recording sites were extracted. The relationships between audible "Velcro-type" crackles and radiologic HRCT patterns and individual features of pulmonary fibrosis were investigated using multivariate regression models. Results: 148 subjects were enrolled: bilateral "Velcro-type" crackles predicted the presence of FILD at HRCT (OR 13.46, 95% CI 5.85-30.96, p < 0.001) and most strongly the Usual Interstitial Pneumonia (UIP) pattern (OR 19.8, 95% CI 5.28-74.25, p < 0.001). Extent of isolated reticulation (OR 2.04, 95% CI 1.62-2.57, p < 0.001), honeycombing (OR 1.88, 95% CI 1.24-2.83, < 0.01), ground glass opacities (OR 1.74, 95% CI 1.29-2.32, p < 0.001) and traction bronchiectasis (OR 1.55, 95% CI 1.03-2.32, p < 0.05) were all independently associated with the presence of "Velcro-type" crackles. Conclusions: "Velcro-type" crackles predict the presence of FILD and directly correlate with the extent of distinct radiologic features of pulmonary fibrosis. Such evidence provides grounds for further investigation of lung sounds as an early identification tool in FILD.

2018 - Analysis of pulmonary sounds for the diagnosis of interstitial lung diseases secondary to rheumatoid arthritis [Articolo su rivista]
Pancaldi, Fabrizio; Sebastiani, Marco; Cassone, Giulia; Luppi, Fabrizio; Cerri, Stefania; Della Casa, Giovanni; Manfredi, Andreina
abstract

The diagnosis of interstitial lung diseases in patients affected by rheumatoid arthritis is fundamental to improving their survival rate. In particular, the average survival time of patients affected by rheumatoid arthritis with pulmonary implications is approximately 3 years. The gold standard for confirming the diagnosis of this disease is computer tomography. However, it is very difficult to raise diagnosis suspicion because the symptoms of the disease are extremely common in elderly people. The detection of the so-called velcro crackle in lung sounds can effectively raise the suspicion of an interstitial disease and speed up diagnosis. However, this task largely relies on the experience of physicians and has not yet been standardized in clinical practice. The diagnosis of interstitial lung diseases based on thorax auscultation still represents an underexplored field in the study of rheumatoid arthritis. In this study, we investigate the problem of the automatic detection of velcro crackle in lung sounds. In practice, the patient is auscultated using a digital stethoscope and the lung sounds are saved to a file. The acquired digital data are then analysed using a suitably developed algorithm. In particular, the proposed solution relies on the empirical observation that the audio bandwidth associated with velcro crackle is larger than that associated with healthy breath sounds. Experimental results from a database of 70 patients affected by rheumatoid arthritis demonstrate that the developed tool can outperform specialized physicians in terms of diagnosing pulmonary disorders. The overall accuracy of the proposed solution is 90:0%, with negative and positive predictive values of 95:0% and 83:3%; respectively, whereas the reliability of physician diagnosis is in the range of 60-70%. The devised algorithm represents an enabling technology for a novel approach to the diagnosis of interstitial lung diseases in patients affected by rheumatoid arthritis.

2018 - Efficacy and safety of extracranial vein angioplasty in multiple sclerosis: A randomized clinical trial [Articolo su rivista]
Zamboni, P.; Tesio, L.; Galimberti, S.; Massacesi, L.; Salvi, F.; D'Alessandro, R.; Cenni, P.; Galeotti, R.; Papini, D.; D'Amico, R.; Simi, S.; Valsecchi, M. G.; Filippini, G.; Ceruti, S.; Conforti, P.; Malagoni, A. M.; Menegatti, E.; Tessari, M.; Pancaldi, F.; Vanini, M. E.; Barbarossa, E.; Bartolomei, I.; Pellegrino, L.; Piscaglia, M. G.; Rasi, F.; Babini, M.; Drea, A.; Guerrini, E.; Lotti, E. M.; Morelli, A.; Peroni, M.; Zalambani, V.; Zecchini, S.; Patti, F.; Chisari, C.; Chiaramonte, I.; Cimino, V.; Giaquinta, A.; Di Pino, L.; Failla, G.; Veroux, P.; Cantello, R.; Leone, M.; Coppo, L.; Guzzardi, G.; Raymkulova, O.; Ruggerone, S.; Stecco, A.; Vecchio, D.; Confalonieri, P. A.; Campanella, A.; Caldiera, V.; Ciceri, E.; Erbetta, A.; Farago, G.; Parma, L.; Reggiori, B.; Clerici, V. T.; Danni, M.; Arborino, S.; De Berardinis, F.; Di Biagio, L.; Orni, C.; Renzi, R.; Rosettani, P.; Zagaglia, S.; Luccioni, G.; Oncini, L.; Quatrini, C.
abstract

Importance: Chronic cerebrospinal venous insufficiency (CCSVI) is characterized by restricted venous outflow from the brain and spinal cord. Whether this condition is associated with multiple sclerosis (MS) and whether venous percutaneous transluminal angioplasty (PTA) is beneficial in persons with MS and CCSVI is controversial. Objective: To determine the efficacy and safety of venous PTA in patients with MS and CCSVI. Design, Setting, and Participants: We analyzed 177 patients with relapsing-remitting MS; 62 were ineligible, including 47 (26.6%) who did not have CCSVI on color Doppler ultrasonography screening. A total of 115 patients were recruited in the study timeframe. All patients underwent a randomized, double-blind, sham-controlled, parallel-group trial in 6MS centers in Italy. The trial began in August 2012 and concluded in March 2016; data were analyzed from April 2016 to September 2016. The analysis was intention to treat. Interventions: Patients were randomly allocated (2:1) to either venous PTA or catheter venography without venous angioplasty (sham). Main Outcomes and Measures: Two primary end pointswere assessed at 12 months: (1) a composite functional measure (ie, walking control, balance, manual dexterity, postvoid residual urine volume, and visual acuity) and (2) a measure of new combined brain lesions on magnetic resonance imaging, including the proportion of lesion-free patients. Combined lesions included T1 gadolinium-enhancing lesions plus new or enlarged T2 lesions. Results: Of the included 115 patients with relapsing-remitting MS, 76 were allocated to the PTA group (45 female [59%]; mean [SD] age, 40.0 [10.3] years) and 39 to the sham group (29 female [74%]; mean [SD] age, 37.5 [10.6] years); 112 (97.4%) completed follow-up. No serious adverse events occurred. Flow restoration was achieved in 38 of 71 patients (54%) in the PTA group. The functional composite measure did not differ between the PTA and sham groups (41.7%vs 48.7%; odds ratio, 0.75; 95%CI, 0.34-1.68; P = .49). The mean (SD) number of combined lesions on magnetic resonance imaging at 6 to 12 months were 0.47 (1.19) in the PTA group vs 1.27 (2.65) in the sham group (mean ratio, 0.37; 95%CI, 0.15-0.91; P = .03: adjusted P = .09) and were 1.40 (4.21) in the PTA group vs 1.95 (3.73) in the sham group at 0 to 12 months (mean ratio, 0.72; 95%CI, 0.32-1.63; P = .45; adjusted P = .45). At follow-up after 6 to 12 months, 58 of 70 patients (83%) in the PTA group and 22 of 33 (67%) in the sham group were free of new lesions on magnetic resonance imaging (odds ratio, 2.64; 95%CI, 1.11-6.28; P = .03; adjusted P = .09). At 0 to 12 months, 46 of 73 patients (63.0%) in the PTA group and 18 of 37 (49%) in the sham group were free of new lesions on magnetic resonance imaging (odds ratio, 1.80; 95%CI, 0.81-4.01; P = .15; adjusted P = .30). Conclusion and Relevance: Venous PTA has proven to be a safe but largely ineffective technique; the treatment cannot be recommended in patients with MS.

2018 - Equalization of Narrowband Indoor Powerline Channels for High Data Rate OFDM Communications [Articolo su rivista]
Pancaldi, Fabrizio; Gianaroli, Fabio; Vitetta, Giorgio Matteo
abstract

In this paper the well known Zadeh’s series representation of a linear periodically time varying system is exploited to develop linear equalization techniques for narrowband powerline communications based on orthogonal frequency division multiplexing. Numerical and experimental results referring to the band 200-500 kHz evidence that a coherent receiver exploiting the proposed equalizers can significantly outperform both its counterpart based on conventional channel estimation/ equalization techniques and differential detection with a limited complexity. This leads to the conclusion that a coherent receiver incorporating the proposed equalization techniques represents a technically appealing solution for narrowband high data rate powerline communications in indoor scenarios.

2017 - NEW PERSPECTIVES IN DIAGNOSIS OF INTERSTITIAL LUNG DISEASE RELATED TO RHEUMATOID ARTHRITIS. VALIDATION STUDY OF AN ELECTRONIC STETHOSCOPE AND AD HOC SOFTWARE FOR DETECTION OF PULMONARY CRACKLES [Abstract in Rivista]
Manfredi, Andreina Teresa; Sebastiani, Marco; Cassone, Giulia; Fedele, A. L.; Venerito, V.; Trevisani, M.; Furini, F.; Addimanda, O.; Gremese, E.; Iannone, F.; DELLA CASA, Giovanni; Cerri, Stefania; Sandri, Gilda; Pancaldi, Fabrizio; Luppi, Fabrizio; Ferri, Clodoveo
abstract

Background: Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial joint swelling and tenderness, secondary to the immune-system dysfunction, often complicated by extra-articular manifestations. Among them, lung involvement is very frequent and interstitial lung disease (ILD) represents one of the deleterious complications of RA with impact on both therapeutic approach and overall prognosis. Nevertheless, diagnosis of ILD often remains missing or delayed. Objectives: To preliminarily evaluate the predictive value of pulmonary sound recorded by an electronic stethoscope (ES) and elaborated by an ad hoc software in identification of RA-ILD diagnosed by mean of high resolution computed tomography (HRCT) in a multicenter study. Methods: RA patients who underwent HRCT in the last 12 months were enrolled. They were all auscultated with the ES (Littmann 3200TM 3M, USA), bilaterally, at dorsal level, in at least 3 pulmonary fields (medium and basal). All tracks recorded were analyzed by a suitably developed software capable of recognizing pathological crackles in lung sounds. Results were compared with radiologic findings detected in a blind manner by an expert radiologist. Results: One hundred and six RA patients were enrolled (M/F: 1/2.5, mean age 68.7±10.3); among them 45 (42.5%) showed ILD at HRCT. Three patients were excluded because of a low quality of the sound recorded. The algorithm showed a sensitivity and specificity of 72.1% and 84.4%, respectively and a positive/negative predictive value of 69.1% and 86.3%, respectively. Conclusions: Despite preliminary, these data suggest an important role of ES in clinical practice for an early diagnosis of ILD in RA patients and a significant reduction of inappropriate prescription of HRCT. Since very different types of ILD can occur in course of RA, with different radiologic features and localization, proper development of the measurement setup (ES and ad hoc software for the detection of PC) could further increase its predictive value, in particular to avoid incorrect records and misdiagnosis. The routinely employment of ES and proper software, combined to clinical findings (cough, dyspnea) and respiratory lung function, could increase our ability to early identify ILD in RA patients.

2016 - Bit and Power Loading for Narrowband Indoor Powerline Communications [Articolo su rivista]
Pancaldi, Fabrizio; Gianaroli, Fabio; Vitetta, Giorgio Matteo
abstract

The problem of bit and power loading for bit rate maximization in orthogonal frequency division multiplexing data communications over indoor powerline channels is investigated, and a simple method for bit/power allocation in half a cycle of the mains is developed. The proposed solution is based on the so-called Zadeh's representation for modeling the linear periodically time-varying behavior of powerline channels. Numerical results show the superiority of the proposed method over other solutions available in the technical literature in a real-world scenario.

2015 - A novel bit and power loading algorithm for narrowband indoor powerline communications [Relazione in Atti di Convegno]
Gianaroli, Fabio; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

The problem of bit and power loading for bit rate maximization in OFDM data communications over indoor powerline channels is investigated and a simple method for bit/power allocation in a single cycle of the mains is developed. The proposed solution is based on the so called Zadeh's representation for modelling the linear periodically time-varying behavior of powerline channels. Numerical results show the superiority of the proposed method over other solutions available in the technical literature in a real world scenario.

2015 - Reduced-Complexity Algorithms for Indoor Map-Aware Localization Systems [Articolo su rivista]
Pancaldi, Fabrizio; Montorsi, Francesco; Vitetta, Giorgio Matteo
abstract

The knowledge of environmental maps (i.e., map-awareness) can appreciably improve the accuracy of optimal methods for position estimation in indoor scenarios. This improvement, however, is achieved at the price of a significant complexity increase with respect to the case of map-unawareness, specially for large maps. This is mainly due to the fact that optimal map-aware estimation algorithms require integrating highly nonlinear functions or solving nonlinear and nonconvex constrained optimization problems. In this paper, various techniques for reducing the complexity of such estimators are developed. In particular, two novel strategies for restricting the search domain of map-aware position estimators are developed and the exploitation of state-of-the-art numerical integration and optimization methods is investigated; this leads to the development of a new family of suboptimal map-aware localization algorithms. Our numerical and experimental results evidence that the accuracy of these algorithms is very close to that offered by their optimal counterparts, despite their significantly lower computational complexity.

2015 - Reduced-complexity techniques for indoor map-aware localization [Relazione in Atti di Convegno]
Montorsi, Francesco; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this manuscript new reduced complexity localization algorithms exploiting received signal strength measurements and based on the indoor map-aware statistical models illustrated in [1] are developed. Such algorithms exploit search domain reduction techniques and state of the art methods for numerical integration and optimization. Our numerical and experimental results evidence that theirs accuracy is very close to that offered by their optimal counterparts, in spite of their substantially lower computational complexity.

2014 - Design and Implementation of a Wideband Channel Sounder for Low-Voltage Powerlines [Articolo su rivista]
Gianaroli, Fabio; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

Estimating the input-output behavior of low voltage powerline channels for indoor high speed data communications requires the availability of proper wideband channel sounding tools. In fact, the properties of real world powerline channels are substantially different from those commonly exhibited by their wireless counterparts, so that standard methods for wireless channel sounding cannot be adapted to a powerline scenario. In this paper, after providing some general design guidelines for powerline channel sounding, a detailed description of a FPGA-based implementation of a wideband powerline channel sounder is provided. Such a tool is based on low cost hardware and is flexible, since it can be easily customized to user needs using a set of simple graphical user interfaces. Some of its specific applications, namely the estimation of the time-varying transfer function of an indoor powerline channel and the evaluation of the power spectral density of the noise affecting it, are illustrated to show the potentialities of the developed equipment.

2014 - Map-aware models for indoor wireless localization systems: an experimental study [Articolo su rivista]
Montorsi, Francesco; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

The accuracy of indoor wireless localization systems can be substantially enhanced by map-awareness, i.e., by the knowledge of the map of the environment in which localization signals are acquired. In fact, this knowledge can be exploited to cancel out, at least to some extent, the signal degradation due to propagation through physical obstructions, i.e., to the so called non-line-of-sight bias. This result can be achieved by developing novel localization techniques that rely on proper map-aware statistical modelling of the measurements they process. In this manuscript a unified statistical model for the measurements acquired in map-aware localization systems based on time-of-arrivaland received signal strength techniques is developed and its experimental validation is illustrated. Finally, the accuracy of the proposed map-aware model is assessed and compared with that offered by its map-unaware counterparts. Our numerical results show that, when the quality of acquired measurements is poor, map-aware modelling can enhance localization accuracy by up to 110% in certain scenarios.

2014 - On the Use of Zadeh's Series Expansion for Modeling and Estimation of Indoor Powerline Channels [Articolo su rivista]
Gianaroli, Fabio; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

Indoor powerline channels usually exhibit a cyclic input–output behavior due to the time-varying impedance of power loads. This makes typical time-invariant system models unsuitable to provide a faithful representation of such channels. In this paper, starting from the so-called Zadeh's series expansion, a discrete-time parametric representation of a linear periodically time-varying system is developed, and it is shown how a reduced-complexity version of it can be adopted to model indoor powerline channels. Then, various methods for estimating the parameters of the proposed representation are developed and compared in terms of performance and complexity. Numerical results evidence that our reduced complexity model is able to provide an accurate representation of indoor powerline channels and is of practical interest for both smart-grid applications and home area networks.

2014 - The Impact of Statistical Noise Modeling on the Error-Rate Performance of OFDM Power-Line Communications [Articolo su rivista]
Gianaroli, Fabio; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper, the impact of statistical noise modelling on the error performance achieved by orthogonal frequency-division multiplexing (OFDM) over indoor broadband power-line channels is investigated. Different classes of statistical models suitable to represent power-line noise are illustrated and their impact on the error performance of a specific OFDM system is assessed via computer simulations. Numerical results are compared with the error performance provided by the same system in the presence of measured power-line noise; this is evidence that a realistic indication of error performance can be achieved only if the power spectral density of the adopted noise model exhibits a good match with that of the measured noise. In practice, this result can be achieved by modeling the power-line noise as a moving average random process of proper order; however, a satisfying match can be achieved as well if other simple noise models available in the technical literature are adopted.

2013 - Broadband system models based on Zadeh's representation for indoor powerline channels: An experimental validation [Relazione in Atti di Convegno]
Gianaroli, Fabio; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

The discrete-time representation of a broadband powerline channel as a linear periodically time variant system poses serious problems in terms of computational complexity. In this paper we exploit the principles of the Zadeh's series expansion to devise a new discrete-time system model, characterized by a limited computational complexity and particularly suitable for an implementation on embedded programmable hardware. Then, we illustrate simple methods for estimating the parameters of the proposed model and apply them to the development of a broadband channel sounding tool for powerlines. Our experimental and numerical results show that the proposed model is able to provide a faithful representation of the periodically time varying behavior of indoor powerline channels.

2013 - Design and implementation of an inertial navigation system for pedestrians based on a low-cost MEMS IMU [Relazione in Atti di Convegno]
Montorsi, Francesco; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

Inertial navigation systems for pedestrians are infrastructure-less and can achieve sub-meter accuracy in the short/medium period. However, when low-cost inertial measurement units (IMU) are employed for their implementation, they suffer from a slowly growing drift between the true pedestrian position and the corresponding estimated position. In this paper we illustrate a novel solution to mitigate such a drift by: a) using only accelerometer and gyroscope measurements (no magnetometers required); b) including the sensor error model parameters in the state vector of an extended Kalman filter; c) adopting a novel soft heuristic for foot stance detection and for zero-velocity updates. Experimental results evidence that our inertial-only navigation system can achieve similar or better performance with respect to pedestrian dead-reckoning systems presented in related studies, although the adopted IMU is less accurate than more expensive counterparts.

2013 - Map-aware RSS localization models and algorithms based on experimental data [Relazione in Atti di Convegno]
Montorsi, F.; Pancaldi, F.; Vitetta, G. M.
abstract

The knowledge of the propagation environment can greatly improve the performance of indoor wireless localization systems, since it can be exploited to cancel out, at least to some extent, the effects of physical obstructions (e.g., walls) degrading the radio signals employed for localization. In indoor localization systems, the propagation environment can be described by maps (e.g., floor plans), which represent a valuable source of knowledge. In this paper a new map-aware statistical model for the measurements acquired in wireless localization systems based on received signal strength is proposed. Experimental results are processed to extract the parameters of the proposed model, which is then exploited to devise map-aware localization algorithms; these are capable of mitigating the non-line-of-sight bias introduced in the measurements by the obstructions modelled by the map. Our numerical results evidence that map-aware modelling can substantially improve localization accuracy in indoor scenarios with respect to map-unaware modelling. © 2013 IEEE.

2013 - The Impact of Load Characterization on the Average Properties of Statistical Models for Powerline Channels [Articolo su rivista]
Gianaroli, Fabio; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper the impact of load characterization on the statistical modeling of indoor powerline channels is investigated in the bandwidth 100 kHz–50 MHz. Our analysis refers to the mean properties of such channels (so that their time-varying features are ignored) and is based on: a) the use of the statistical channel simulator, which has beenvalidated through experimental measurements, described in [23]; b) the availability of a set of experimental results about the impedance of various appliances. Our numerical and experimental results evidence that, on the one hand,for frequencies beyond 20 MHz the influence of load characterization on the accuracy of statistical channel modelling is marginal; however, on the other hand, for frequencies in the order of 0–20 MHz the properties of the loads connected to a power network can appreciably affect the properties of the channel model.

2013 - Wireless Communications: Algorithmic Techniques [Monografia/Trattato scientifico]
Vitetta, Giorgio Matteo; D. P., Taylor; Colavolpe, Giulio; Pancaldi, Fabrizio; P. A., Martin
abstract

Digital radios have undergone an astonishing evolution in the last century. Born as a set of simple and power-hungry electrical and electromechanical devices for low data rate transmission of telegraph data in the Marconi age, they have transformed, thanks to substantial advances in electronic technology, into a set of small, reliable and sophisticated integrated devices supporting broadband multimedia communications. This, however, would not have been possible unless significant progress had been made in recent decades in the field of signal processing algorithms for baseband and passband signals. In fact, the core of any modern digital radio consists of a set of algorithms running over programmable electronic hardware. This book stems from the research and teaching activities of its co-authors in the field of algorithmic techniques for wireless communications. A huge body of technical literature has accumulated in the last four decades in this area, and an extensive coverage of all its important aspects in a single textbook is impossible. For this reason, we have selected a few important topics and, for ease of reading, organized them into two parts. Part I concerns digital modulation techniques, characterization and modeling of wireless channels, channel estimation, and channel equalization metrics and algorithms. Part II focuses on channel coding, coded modulation, and combined equalization and decoding. For each of these topics, we have tried to provide an advanced introduction, blending basic principles with advanced concepts and techniques which play an important role at the forefront of research in wireless communications. In addition, for each topic we have provided some historical notes, so that the reader can analyze it in the right perspective, understanding both its roots and its possible evolutionary paths. From the outset our main goal has been to produce a textbook for beginning graduate and senior students, who are expected to have some basic knowledge in the fields of Fourier transform techniques, probability theory, random processes, sampling theory, linear filtering, vector spaces, matrix algebra and linear transformations. Some information about more advanced concepts in these fields is provided in the appendices of the book, which, for this reason, we believe to be self-contained. This book can serve as a text in either one-semester or two-semester courses in digital communications and coding. A natural division is to cover Part I in the first semester and Part II in the second. An alternative one-semester course can cover a portion of the material of Part I (Chapters 1–4 and 6) and some basic material from Part II (Chapters 7–9). The writing of this book has required a substantial commitment. We owe much to all those people who volunteered to read parts of it, correct mistakes and provide suggestions for enriching its technical content and improving its clarity of presentation. In particular, we are grateful Francesco Montorsi, Fabio Gianaroli, Tommaso Foggi, Amina Piemontese, Nicolò Mazzali, Andrea Modenini and Alessandro Ugolini for their contributions. Our sincere thanks go also to the editorial staff of Wiley and, in particular, to Mark Hammond, Sarah Hinton, Jennifer Beal, and Susan Barclay, who have always supported us in the writing process. We do hope that the uncountable hours devoted to this book will bear fruit in stimulating interest in the study of modern techniques for wireless communications.

2012 - Statistical Modeling of Periodic Impulsive Noise in Indoor Power-Line Channels [Articolo su rivista]
Gianaroli, Fabio; Pancaldi, Fabrizio; E., Sironi; Vigilante, Marco; Vitetta, Giorgio Matteo; Barbieri, Alessandro
abstract

In this paper, novel statistical models for the representation of the periodic impulsive noise generated by power loads connected to power grids in indoor scenarios are developed. Their derivation is based on a set of experimental results acquired in a measurement campaign and on deseasonalized autoregressive moving average modeling of cyclostationary random processes. Numerical results are evidence that the proposed models can provide an accurate stochastic representation of the periodic impulsive noise generated by specific appliances in the 1–30 MHz band, at the price of limited computational complexity.

2011 - A Novel Ultrawideband System for Multiuser Data Communications [Articolo su rivista]
Barbieri, A.; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper, a novel ultrawideband system for multiuser data communications is proposed. In this system multiple users are allowed to transmit on-off keying modulated signals in the same time intervals and exploiting the same frequency subband. Time/frequency overlapped data frames sent by distinct users include low data rate training sequences characterized by different repetition periods. This transmission strategy, known as rate division multiple access in the technical literature, allows to ease two fundamental tasks at the receive side, namely joint channel estimation and timing synchronization. Channel estimates are exploited by a multiuser detector based on a zero forcing equalizer. Numerical results evidence that the proposed solution yields good error performance at the price of a limited complexity.

2011 - Compressed channel estimation and data detection algorithms for IR-UWB [Relazione in Atti di Convegno]
A., Barbieri; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper compressed sensing (CS) techniques are employed to develop reduced sampling rate strategies for channel estimation and data detection in impulse radio ultrawideband (IR-UWB) systems. In particular, first channel estimation algorithms based on Matching Pursuit (MP) and Basis Pursuit Denoising (BPDN) techniques are proposed. Then, it is shown how the channel estimates generated by these algorithms can be used in correlation-based CS detectors. Finally, the performance loss originating from CS is assessed analytically in a transmitted reference (TR) system.

2011 - Cross-Layer Design for Double-String Cooperative Communications in Wireless Ad-hoc Networks [Articolo su rivista]
Sergi, Simone; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

This paper proposes a novel architecture for cooperative communication in wireless ad-hoc networks capable of offering reliable and low-latency services efficiently. The proposed solution is characterised by the following relevant features: (i) a wireless connection between each couple of network nodes is established via multiple relays; (ii) each source-to-destination link is characterised by a double-string topology, allowing the use of specific transmit diversity techniques for reliable communications; and (iii) a novel utility-based routing metric providing a fair exploitation of the available energy/bandwidth resources is employed. Simulation results evidence that our solution offers substantial energy savings with respect to traditional ad-hoc architectures employing multihop routing and operating in the absence of cooperativestrategies.

2011 - Statistical characterization and mitigation of NLOS errors in UWB localization systems [Relazione in Atti di Convegno]
Montorsi, Francesco; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

Abstract-In this paper some new experimental results about the statistical characterization of the non-line-oJ-sight (NLOS) bias affecting time-oj-arrival (TOA) estimation in ultrawideband (UWB) wireless localization systems are illustrated. Then, these results are exploited to assess the performance of variousmaximum-likelihood (ML) based algorithms for joint TOA localization and NLOS bias mitigation. Our numerical results evidence that the accuracy of all the considered algorithms is appreciably influenced by the LOSINLOS conditions of the propagation environment.

2010 - A Game Theoretical Approach to the Management of Transmission Selection Scheme in Wireless Ad-Hoc Networks [Articolo su rivista]
Sergi, Simone; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper, game theory is exploited to derive a novel solution to manage virtual antenna array based transmissions in an ad hoc wireless network consisting of selfish nodes. In the proposed strategy each node decides, in an autonomous fashion, whether and when transmitting data packets over a shared wireless channel. The resulting transmission scheme results to be functionally equivalent to a distributed transmission selection scheme, managed, however, in a fully distributed fashion. This approach offers an higher throughput level and an higher efficiency than other communication protocols implementing selection diversity in distributed multi-antenna systems.

2010 - A Novel Approach to Power-Line Channel Modeling [Articolo su rivista]
F., Gianaroli; Barbieri, Alessandro; Pancaldi, Fabrizio; Mazzanti, Andrea; Vitetta, Giorgio Matteo
abstract

In this paper, a novel approach to statistical modelingof power-line channels is illustrated and its application tolow-voltage indoor power networks is analyzed in the bandwidth1–30 MHz. The proposed approach is based on the well-knownbifilar model and on a generalization of the so-called -branchnetwork topology. It is shown that our model can be exploitedto devise an efficient channel simulator predicting the meanimpedance matrix and transfer function between an arbitrarycouple of plugs in a class of indoor networks sharing multipleparameters (e.g., number of branches, minimum and maximumcable lengths, power-loading conditions). Finally, it is shown thatMonte Carlo results generated by our simulator are in good agreementwith a set of experimental data acquired in a measurementcampaign.

2010 - Channel estimation and data detection algorithms for UWB multiuser communications [Relazione in Atti di Convegno]
Barbieri, Alessandro; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper, a novel ultrawideband system for multiuser data communications is proposed. At the transmit side multiple users are allowed to send pulse position modulated signals in a synchronized fashion exploiting a given frequency subband in the same time intervals. Overlapped data frames sent by distinct users include low data rate training sequences with different repetition periods. This transmission strategy, known as rate division multiple access in the technical literature, allows to ease the first two fundamental tasks at the receive side, namely joint channel estimation and timing synchronization. Channel estimates are exploited by a multiuser detector based on the Viterbi algorithm and separating the contribution generated by the user of interest from those produced by all the other co-channel users. Numerical results evidence that the proposed solution can offer an efficient usage of the available spectrum at the price of a limited complexity.

2010 - Cluster-Based Ranging for Accurate Localization in Wireless Sensor Networks [Articolo su rivista]
Sergi, Simone; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

A novel ranging technique based on received signal strength (RSS) and suitable to indoor scenarios is illustrated. In the proposedtechnique, multiple power measurements, associated with the signals radiated by a cluster of nodes surrounding a given target,are jointly processed to improve the quality of RSS-based estimation of the distance between the target and an anchor. Specificalgorithms for the generation of a cluster and for the acquisition of power measurements are described. Simulation results showthat, when used in indoor positioning systems, the proposed ranging technique is substantiallymore accurate than noncooperativestrategies. In addition, it allows to concentrate significant processing tasks in a limited number of fixed anchors, so reducingmaintenance costs and making it possible to adopt cheap and simple portable wireless nodes.

2010 - Space-time block codes for noncoherent CPFSK [Articolo su rivista]
Pancaldi, Fabrizio; Barbieri, Alessandro; Vitetta, Giorgio Matteo
abstract

In this paper the problem of space-time block coding for multiple-input multiple-output communication systems employing continuous phase frequency shift keying and one-shot noncoherent detection is investigated. First, the detection problemis analysed in a maximum likelihood perspective; then, designcriteria for optimal space-time codes are proposed and someerror bounds are derived. Finally, some numerical results areillustrated for a couple of novel space-time block codes designedon the basis of the above mentioned criteria. Such results evidence that the use of the proposed schemes can entail a limited energy loss respect to other solutions available in the technical literature for coherent systems, with the relevant advantage, however, of a simple detection algorithm.

2009 - A Game Theory Approach to Selection Diversity in Wireless Ad-Hoc Networks [Relazione in Atti di Convegno]
Sergi, Simone; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper game theory is exploited to derive an optimal solution to the problem of cooperative data transmission based on distributed selection diversity in an ad hoc wireless network consisting of selfish nodes. First, a credit-based micro-economical model is proposed to manage node interaction; then, a transmission strategy maximizing node utility is derived. In the proposed strategy each node decides, in an autonomous fashion, whether and when transmitting data packets over a shared wireless channel. Numerical results evidence that this approach can ensure both fairness in the access to a shared medium and excellent network efficiency. In particular, it offers an higher throughput level than other communication protocols implementing selection diversity in distributed multi-antenna systems.

2009 - Cluster-Based Ranging for Accurate Localization in Wireless Sensor Neworks [Relazione in Atti di Convegno]
Sergi, Simone; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper a novel ranging technique based on received signal strength (RSS) and suitable to indoor scenarios is illustrated. The proposed technique improves the quality of RSS- based estimation of an anchor-target distance processing multiple power measurements associated with the signals radiated by a cluster of nodes surrounding the target. Specific algorithms for the generation of a cluster and for the acquisition of power measurements are described. Simulation results show that, when used in indoor positioning systems, the proposed ranging technique is substantially more accurate than non cooperative strategies. In addition it allows to concentrate significant processing tasks in a limited number of fixed anchors, so reducing maintenance costs and making possible to adopt cheap and simple portable wireless nodes.

2009 - Cooperative Communication Techniques for Wireless OFDMA-Based Ad-Hoc Networks [Relazione in Atti di Convegno]
Sergi, Simone; Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

This paper proposes a new architecture for cooperative communication in wireless ad-hoc networks particularly suitable to emergency and safety applications. The proposed solution is characterized by the following relevant features: (a) a wireless connection between each couple of network nodes is established via multiple relays; (b) each source-to-destination link is characterized by a double string topology allowing the use of specific transmit diversity techniques for reliable communications; (c) a novel utility-based and distributed routing algorithm providing a fair exploitation of the available resources is employed. Simulation results evidence that our solution offers substantial energy savings with respect to traditional ad-hoc architectures.

2009 - High Altitude Platforms for Telecommunications: Design Methodology [Relazione in Atti di Convegno]
Trancossi, Michele; Dumas, Antonio; Anzillotti, Stefano; Pancaldi, Fabrizio
abstract

High Altitude Platforms (HAPs) represents an appealing solution to deliver low cost broadband access to telecommunication (TLC) networks. However, this potential can be disclosed only if a proper technology is identified in the design of airships and aircrafts. This paper first presents the innovative services which can be provided by a fleet of HAPs in the field of information and communication technology (ICT), and then a novel approach to a modular the design of HAPs is presented. In particular, this study consists of a theoretical investigation and energetic design of an HAP derived from a new class of stratospheric airship for the production of energy at high quote. In practice the energy is harvested by photovoltaic panels and stored in hydrogen fuel cells. We denote this new technology with the acronym P.S.I.C.H.E. (Photovoltaic Space Island for Conversion of Hydrogen as Energy vector). In this paper authors consider the problems connected to the dimensional scalability of the system in order to verify the possibility of producing a reduced version of P.S.I.C.H.E. for telecommunication services only. This platform for telecommunication can operate over northern Italy (about 45mD latitude north) at altitudes between 15-16 Km. Operative altitude and volume of lifting gas can vary as a function of winds in any other location all over the world. By these considerations authors are going to propose a novel iterative design methodology to dimension an airship characterized by a shape with a vertical rotation axis.

2008 - Single-Carrier Frequency Domain Equalization [Articolo su rivista]
Pancaldi, Fabrizio; Vitetta, Giorgio Matteo; R., Kalbasi; N., Al Dhahir; M., Uysal; H., Mheidat
abstract

Orthogonal frequency division multiplexing (OFDM) has been recently adopted by major manufacturers and by standardization bodies for a wide range of wireless and wireline applications ranging from digital video/audio broadcasting to power-line communications. The major virtues of OFDM are 1) its resilience to multipath propagation providing a viable low-complexity and optimal (in the maximum likelihood sense) solution for intersymbol interference (ISI) mitigation, 2) the possibility of achieving channel capacity if the transmitted signal is adapted to the state of the communication channel (i.e., if energy and it-loading procedures are adopted), and 3) the availability of strategies for frequency diversity scheduling in multiuser communication systems. Although OFDM has become the physical layer of choice for broadband communications standards, it suffers from several drawbacks including a large peak-to-averagepower ratio (PAPR), intolerance to amplifier nonlinearities, and high sensitivity to carrier frequency offsets (CFOs) [6]. An alternative promising approach to ISI mitigation is the use ofsingle-carrier (SC) modulation combined with frequencydomainequalization (FDE). On the one hand, the complexityand performance of SC-FDE systems is comparable to that of OFDM while avoiding the above mentioned drawbacks associatedwith multicarrier (MC) implementation. On the other hand,FDE does not represent an optimal solution to signal detectionover ISI channels and SC systems cannot certainly offer thesame flexibility as OFDM in the management of bandwidth andenergy resources, both in single user and in multiuser communications.All these considerations have made the choicebetween SC-FDE and OFDM a strongly debated issue in academicand industrial circles. For this reason, we believe that SC-FDEtechniques deserve a deeper analysis in view of the significantattention given to MC techniques. The first MC scheme was proposed in 1966 [1], whereas the first approach to SC-FDE in digital communication systems dates back to 1973 [2]. Despite thesmall time separation between their introductions, many effortshave been devoted by the scientific community to the study ofMC solutions, but little attention has been paid to SC-FDE formany years. In the last decade, there has been a renewed interest in this area. The theoretical and practical gap between thetwo solutions is tightening, but the technical literature on MCcommunication is by far larger than that on SC-FDE. In thisarticle, we intend to provide an overview of the principles of SCFDE with a particular focus on wireless applications and to present an up-to-date review including the latest and most relevant research results in the SC-FDE area. Our article is tutorial in nature and, therefore, our emphasis is not on detailed mathematical derivations but rather on describing the salient features of SC-FDE techniques and comparing it to its MC counterpart.

2006 - Equalization algorithms in the frequency domain for continuous phase modulations [Articolo su rivista]
Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper, novel equalization algorithms for continuous phase modulations (CPMs) are illustrated. Both conventional (linear and decision-feedback) and turbo equalization techniques are derived using the Laurent decomposition of CPM signals. All of them operate in the frequency domain and process two samples of the received signal per channel symbol. Numerical results show that on one hand, conventional equalization strategies offer good performance for binary partial response signaling over severely frequency-selective wireless channels at a moderate complexity. On the other hand, there is evidence that turbo techniques provide a small energy saving at the price of a substantial computational burden.

2006 - GQR-based models for directional wireless channels [Articolo su rivista]
Pancaldi, Fabrizio; P., Greco; Vitetta, Giorgio Matteo
abstract

In this paper novel reduced complexity statistical models for the representation of directional wireless channels affected by Rayleigh fading are developed. Their derivation is based on the evaluation of Fourier integrals by means of Gaussian quadrature rules (GQRs). The proposed models represent a communication channel as a tapped-angle and -delay line with non uniform spacing between successive taps. The application of the GQR approach to three different scenarios is also illustrated. Numerical results evidence that these models can provide a simple and accurate stochastic representation of directional fading channels.

2006 - Space-time block coding for noncoherently detected CPFSK [Relazione in Atti di Convegno]
Pancaldi, F.; Vitetta, G. M.
abstract

In this paper the problem of unitary rate space-time block coding for multiple-input multiple-output communication systems employing continuous phase frequency shift keying is investigated. First, the problem of optimal codeword by codeword noncoherent detection is analysed; then, design criteria for optimal space-time block codes are proposed and some novel coding schemes are devised. Simulation results evidence that the proposed schemes can efficiently exploit spatial diversity and that their use can entail a limited energy loss with respect to other solutions available in the technical literature for coherent systems, with the substantial advantage, however, of a simple detection algorithm.

2005 - Block channel equalization in the frequency domain [Articolo su rivista]
Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper, channel equalization algorithms processing two samples of the received signal per channel symbol and operating in the frequency domain are described in a unifying framework. First, minimum mean-square error linear and decision-feedback equalizers are derived, and a synthesis technique based on the well-known Levinson-Durbin algorithm is proposed for the latter. Then, iterative linear and decision-feedback equalization algorithms for turbo processing are devised. Performance results for both uncoded and coded phase-shift keying transmissions show the efficacy of the proposed equalization techniques and their superiority over other existing frequency-domain equalization strategies.

2005 - Equalization Algorithms in the Frequency Domain for Continuous Phase Modulations [Relazione in Atti di Convegno]
Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper novel linear and decision feedback equalization algorithms for continuous phase modulations (CPMs) are illustrated. These algorithms operate in the frequency domain and process two samples of the received signal per channel symbol. Their derivation is based on the Laurent decomposition of CPM signals. Numerical results evidence that the proposed techniques enable the use of CPMs over severely frequency selective wireless channels.

2005 - Frequency-domain equalization for space-time block-coded systems [Articolo su rivista]
Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper, conventional and turbo-channel-equalization algorithms processing two samples of the received signal per channel symbol and operating in the frequency domain are proposed for space-time block-coded systems. In the class of conventional equalization techniques, minimum-mean-square-error (MAISE) linear and decision-feedback equalizers (DFE) are derived and a synthesis technique based on the well-known Levinson-Durbin algorithm is proposed for the latter. Similarly, iterative linear and decision-feedback-equalization algorithms for turbo receivers are devised. Performance results show the efficacy of the proposed equalization techniques and their superiority over other frequency-domain-equalization strategies.

2005 - Space-Time Block Codes for Noncoherent CPFSK [Relazione in Atti di Convegno]
Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this paper the problem of unitary rate space-time block coding for multiple-input multiple-output communication systems employing continuous phase frequency shift keying is investigated. First, one-shot noncoherent detection is analysed in a maximum likelihood perspective; then, design criteria for optimal space-time codes are proposed and some error bounds for the devised coding schemes are derived. Numerical results evidence that the use of the proposed coding schemes can entail a limited energy loss with respect to other solutions available in the technical literature for coherent systems, with the relevant advantage, however, of a simple detection algorithm

2004 - Block equalization techniques in the frequency domain [Relazione in Atti di Convegno]
Pancaldi, Fabrizio; Vitetta, Giorgio Matteo
abstract

In this work various channel equalization algorithms operating in the frequency domain are described in a unifying framework. First, minimum mean square error linear and decision-feedback equalizers are derived and a synthesis technique based on the well-known Levinson-Durbin algorithm is proposed for the latter. Then, iterative linear and decision feedback equalization algorithms for turbo processing are devised. Performance results for both uncoded and coded PSK transmissions show the efficacy of the proposed equalization techniques and their superiority over other existing frequency domain equalization strategies.

2004 - GQR models for directional wireless channels [Relazione in Atti di Convegno]
L., Fregni; F., Muratori; P., Greco; Vitetta, Giorgio Matteo; Pancaldi, Fabrizio
abstract

In this paper novel reduced complexity statisticalmodels for the representation of wide sense stationary–uncorrelated scattering directional wireless channels affected byRayleigh fading are developed. Their derivation is based on theso-called Gaussian quadrature rule approach illustrated in [1] fornon directional channels. Numerical results evidence that theproposed models can provide a simple and accurate stochasticrepresentation of directional fading channels.

2003 - GQR models for directional wireless channels [Relazione in Atti di Convegno]
Fregni, Lodovico; Muratori, Fabrizio; Greco, Paola; Vitetta, Giorgio Matteo; Pancaldi, Fabrizio
abstract

In this paper, a novel reduced complexity statistical models for the representation of wide sense stationary-uncorrelated scattering directional wireless channels affected by Rayleigh fading are developed. Their derivation is based on the so-called Gaussian quadrature rule approach illustrated by E. Chiavaccini and G. M. Vitetta (June 2001) for non directional channels. Numerical results evidence, that the proposed models provide a simple and accurate stochastic representation of directional fading channels.