Rivelazione di Segnali a Fase Continua per Comunicazioni via Satellite

Si propone qui uno studio sulle Modulazioni a Fase Continua (CPM). Dopo una prima parte rivolta all'analisi di un metodo numerico per il calcolo della densità spettrale, ci concentreremo sulle prestazioni dei segnali CPM valutandone efficienza energetica ed efficienza spettrale al variare di alcuni parametri (indice di modulazione, ordine della costellazione, forma degli impulsi). I risultati ottenuti saranno poi visualizzati sul piano di Shannon per poter avere un confronto con le attuali tecniche di modulazione digitale normalmente in uso. Infine focalizzeremo l'attenzione sull'analisi della probabilità di errore in presenza di offset di fase

Mental fatigue impairs physical activity, technical and decision-making performance during small-sided games

The aim of this study was to investigate the effects of mental fatigue on physical activity, technical and decision-making performance during small-sided games. Nine sub-elite soccer players were enrolled in the study. The players performed two small-sided games on two occasions within a crossover experimental design. Before each game, they underwent a mental fatiguing task (Stroop task) and a control task (documentary watching) in a randomized, counterbalanced order. Players' physical activity, technical, and decision-making performance were obtained during small-sided games by GPS and video scouting. Results showed that distance in acceleration covered per min, negative passes, passing accuracy, and shot accuracy were likely impaired than control task after a mental fatiguing protocol. Decision-making performance of negative passes, passes accuracy, and dribbling accuracy resulted also likely decreased compared with control task. These findings demonstrated that mental fatigue impacted on technical, GPS-derived, and soccer-specific decision-making performance during SSG. In conclusion, avoiding cognitively demanding tasks before playing soccer-specific activities may be advisable to preserve players' physical activity, technical, and decision-making skills

Spectrally Efficient Waveforms for the Return Link in Satellite Communication Systems

In this paper, we study the applicability of terrestrial mobile waveforms in the return link of a high throughput satellite (HTS) communication system. These include orthogonal frequency division multiple access (OFDMA), single-carrier frequency division multiple access (SC-FDMA) and filter bank multi-carrier (FBMC). Key solutions to the challenges in a geostationary orbit (GEO) satellite channel, such as synchronization and non-linear distortion, are presented. A global-positioning-system-(GPS)-based approach for synchronization acquisition is proposed, while suitable algorithms are studied for timing/frequency offset estimation and synchronization tracking. The spectral and power efficiencies of the schemes are optimized by means of an intermodulation interference (IMI) cancelling receiver, and these are compared to state-of-the-art time division multiple access (TDMA). Finally, end-to-end simulations validate the system performance

West Nile virus transmission. results from the integrated surveillance system in Italy, 2008 to 2015

IIn Italy a national Plan for the surveillance of imported and autochthonous human vector-borne diseases (chikungunya, dengue, Zika virus disease and West Nile virus (WNV) disease) that integrates human and veterinary (animals and vectors) surveillance, is issued and revised annually according with the observed epidemiological changes. Here we describe results of the WNV integrated veterinary and human surveillance systems in Italy from 2008 to 2015. A real time data exchange protocol is in place between the surveillance systems to rapidly identify occurrence of human and animal cases and to define and update the map of affected areas i.e. provinces during the vector activity period from June to October. WNV continues to cause severe illnesses in Italy during every transmission season, albeit cases are sporadic and the epidemiology varies by virus lineage and geographic area. The integration of surveillance activities and a multidisciplinary approach made it possible and have been fundamental in supporting implementation of and/or strengthening preventive measures aimed at reducing the risk of transmission of WNV trough blood, tissues and organ donation and to implementing further measures for vector control

Topics in signal design and detection for broadband satellite communications

This thesis deals with different aspects of modern satellite communications. Satellite-based telecom systems provide the best and quickest solution to reducing the digital divide in less-favored areas owing to their wide geographical coverage and the speed and ease of deployment of terminal equipment. However, satellite system must be efficient and cost effective, and capable of full inter-working with state-of-the-art terrestrial broadband networks. The first part of this thesis presents a novel two-way broadband satellite architecture. The system provides TV-Centric triple play services to actual end-users in the home employing DVB-S2 and DVB-RCS technologies in the forward and the return link, respectively, together with a newly dynamic resource allocation technique based on the adoption of the Adaptive Coding & Modulation (ACM) functionality together with a QoS policy. The second part analyses alternative satellite transmission schemes reporting benefits and proposing solution to tackle critical issues for two attractive solutions: OFDM and CPM. OFDM technologies are largely used in terrestrial networks but they are not very popular in satellite systems due to the large peak-to-average power ratio. The multicarrier nonlinear channel capacity is derived together with a predistortion algorithm, based on the fixed point iteration (FPI), to mitigate the nonlinear distortions. The performance of a turbo-coded FPI-predistorted OFDM system in the nonlinear channel is also presented. Continuous-phase modulations (CPMs) have the attractive properties of constant envelope and bandwidth efficiency, that make this family the most suitable modulation in the satellite field. In spite of these favourable features the CPMs have found no application until now, except for very simple schemes as MSK, because of the implementation complexity of the detector, and of synchronization problems. Two synchronization algorithms, a cyclostationary-based timing estimator and a soft-based phase recovery method for CPMs, are derived and the Root-Mean Square Estimation Error is shown to assess the performance. A spectral analysis identifying a subclass of CPM signals that are suited for future global navigation satellite systems in the C-band region is also presented