1,721,000 research outputs found
Guest Editorial Introduction to the Special section on AI-powered internet of everything (IoE) services in next-generation wireless networks
No full textToward Energy-Efficient Distributed Federated Learning for 6G Networks
Full text linkThe provision of communication services via portable and mobile devices, such as aerial base stations, is a crucial concept to be realized in 5G/6G
networks. Conventionally, IoT/edge devices need to transmit data directly to the base station for training the model using machine learning techniques.
The data transmission introduces privacy issues that might lead to security concerns and monetary losses. Recently, federated learning was proposed to
partially solve privacy issues via model sharing with the base station. However, the centralized nature of federated learning only allows the devices within the vicinity of base stations to share trained models. Furthermore, the long-range communication compels the devices to increase transmission power, which raises energy efficiency concerns. In this work, we propose the distributed federated learning (DBFL) framework that overcomes the connectivity and energy efficiency issues for distant devices. The DBFL framework is compatible with mobile edge computing architecture that connects the devices in a distributed manner using clustering protocols. Experimental results show that the framework increases the classification performance by 7.4 percent in comparison to conventional federated learning while reducing the energy consumption
Impact of Propagation Impairments on Outdoor and Indoor Optical Wireless Communications
No full textIn this contribution, we discuss the impact of propagation impairments in indoor and outdoor optical wireless communication. In outdoor terrestrial systems, fog attenuation is the major effect which limit the link length whereas in indoor systems, multipath bounds the available bandwidth and both above parameters quantified through measurements and simulations
Joint Optimization of Semi-Passive IRS Phase Shifts and NOMA Power Coefficients for Cooperative CRNs
Full text linkWe investigate the incorporation of an intelligent reflecting surface (IRS) into cooperative spectrum-sharing cognitive radio networks (CRNs). The CRN consists of a primary user (PU) and multiple secondary users (SUs). There are two transmission phases. In the first phase, the primary transmitter is assisted by an IRS to serve the primary user (PU). This arrangement allows the primary network to allocate a part of its spectrum to the users within the secondary network. In the subsequent phase, the secondary transmitter (ST) employs a non-orthogonal multiple access (NOMA) transmission technique to simultaneously serve the PU and secondary users (SUs). By utilizing a semi-passive IRS, both data transmission to the PU and channel estimation of SUs are performed simultaneously during the first transmission phase. The main objective is to improve the weighted sum-rate of the CRN through a joint optimization of the NOMA power coefficients and IRS phase adjustments during the second transmission phase. We propose an effective algorithm that breaks down the primary sum-rate maximization problem into two sub-problems where IRS phase shifts are computed once at the beginning of the algorithm. Through simulations, we demonstrate that the proposed algorithm yields substantial gains in the sum-rate performance compared to existing methods
Towards defining industry 5.0 vision with intelligent and softwarized wireless network architectures and services:A survey
No full textIndustry 5.0 vision, a step toward the next industrial revolution and enhancement to Industry 4.0, conceives the new goals of resilient, sustainable, and human-centric approaches in diverse emerging applications such as factories-of-the-future and digital society. The vision seeks to leverage human intelligence and creativity in nexus with intelligent, efficient, and reliable cognitive collaborating robots (cobots) to achieve zero waste, zero-defect, and mass customization-based manufacturing solutions. However, it requires merging distinctive cyber–physical worlds through intelligent orchestration of various technological enablers, e.g., cognitive cobots, human-centric artificial intelligence (AI), cyber–physical systems, digital twins, hyperconverged data storage and computing, communication infrastructure, and others. In this regard, the convergence of the emerging computational intelligence (CI) paradigm and softwarized next-generation wireless networks (NGWNs) can fulfill the stringent communication and computation requirements of the technological enablers of the Industry 5.0, which is the aim of this survey. In this article, we address this issue by reviewing and analyzing current emerging concepts and technologies, e.g., CI tools and frameworks, network-in-box architecture, open radio access networks, softwarized service architectures, potential enabling services, and others, elemental and holistic for designing the objectives of CI-NGWNs to fulfill the Industry 5.0 vision requirements. Furthermore, we outline and discuss ongoing initiatives, demos, and frameworks linked to Industry 5.0. Finally, we provide a list of lessons learned from our detailed review, research challenges, and open issues that should be addressed in CI-NGWNs to realize Industry 5.0.</p
Dielectric Parameter Estimation at Ka-Band using Bayesian Inversion Method
No full textThis paper presents the estimation of dielectric material properties such as relative permittivity and thickness, using the well-known Bayesian inversion method. The free space measurements are conducted to obtain the S-parameters of the materials under test and passed forward to the time domain Bayesian inversion process to estimate the material properties and show the confidence on the accuracy of the results. The measurements were carried out at Ka (26-40GHz) band using commercial Vector Network Analyzer and MATLAB was used for post-processing of results. This method can provide better accuracy and improvement in Nondestructive Testing (NDT) and various quality control systems
Synthesis of attenuation time series across FSO link for the design of a backhauling solution for 5G beyond networks
Full text linkLa comunicazione FREE Space Optical (FSO) è una delle tecnologie più studiate per le sue caratteristiche molto interessanti come alta velocità di trasmissione dati, licenza libera, assenza di interferenze elettromagnetiche, peso leggero, volume ridotto, sicurezza dovuta a fascio laser stretto, portabilità e basso consumo energetico. Tuttavia, si verificano alcune limitazioni dovute alla dipendenza dalle condizioni meteorologiche che comprendono la dispersione e l'assorbimento, causati da gas e vari idrometri, essendo la nebbia il problema più difficile che ha un impatto maggiore sulle prestazioni del collegamento FSO.
Dal punto di vista applicativo, sappiamo che per fornire agli utenti 5G opportunità di tecnologia per utilizzare una larghezza di banda estremamente elevata è necessario l'uso di una rete densa con mini stazioni base a breve raggio (alcuni 100 metri) che possono essere collegate in due modi, ad esempio cablate o wireless. La risoluzione della connettività di backhaul è fondamentale prima che eventuali implementazioni di piccole celle 5G possano scalare. Non c'è modo di considerare anche l'aggiunta di drop backhaul cablati a migliaia di siti in un ambiente urbano che sarà costoso e richiederà più tempo e sforzi fisici. A tale riguardo, i collegamenti FSO possono gestire la scala, sono facili da implementare, hanno una capacità molto elevata e rappresentano una soluzione economica su una distanza di 100 metri. È essenziale che gli operatori che pianificano la distribuzione di piccole celle ad alta densità considerino seriamente l'FSO come un'opzione prima che inizino le implementazioni 5G. Al fine di utilizzare l'FSO per il backhauling, il nostro lavoro proposto è molto utile nel fornire la metodologia per generare valori di attenuazione sintetici dello sbiadimento del segnale e le sue caratteristiche in diverse condizioni di bassa visibilità ancor prima della distribuzione.
Questo lavoro di ricerca è diretto a proporre una procedura per un sintetizzatore di serie temporali di attenuazione sintetica per eventi a bassa visibilità lungo i collegamenti ottici terrestri a spazio libero utili per la progettazione di reti di backhauling 5G. A tale scopo, è stata effettuata la pre-elaborazione per il corretto utilizzo dei dati, che include l'identificazione degli eventi a bassa visibilità con approccio ottimale, la rimozione di bias in media e la base di eventi e l'identificazione del miglior valore di integrazione temporale per tutti e tre i database. Successivamente, è dimostrato che la visibilità è adatta per derivare serie temporali di attenuazione su un campionamento a tempo lento, ma per campionamento temporale veloce, viene proposta una tecnica statistica generale. Dopo aver fatto una vasta letteratura, abbiamo selezionato una procedura per lo sviluppo di un sintetizzatore di serie storiche tra quelle proposte per l'onda millimetrica e modificato la procedura con l'introduzione di serie temporali di visibilità all'ingresso invece di utilizzare serie di serie temporali di attenuazione di grandi dimensioni. Inoltre, le variazioni veloci ottenute attraverso la tecnica statistica saranno sovrapposte a una dissolvenza lenta che ha reso più accurate le serie temporali di attenuazione sintetica previste. Infine, dopo l'esecuzione dettagliata della procedura passo passo, le serie temporali di attenuazione sintetica sono costituite da una componente sintetica (Fast Fading) ciascuna sovrapposta a un componente ottenuto manipolando i dati misurati (Slow Fading).
Ampio database di dati misurati raccolti presso il Politecnico di Milano e in altri due siti sperimentali dell'Europa sono considerati validi per validare il lavoro proposto. Abbiamo testato la nostra procedura su tutti gli eventi dei diversi siti e confrontato l'attenuazione delle serie temporali sintetiche con quella misurata su base statistica. Questo test si basa sul numero di indicatori: valore medio, deviazione standard e RMSE. Nel complesso, abbiamo riscontrato un risultato eccellente in quanto l'88,88% degli eventi ha 1 dB / km e 0,5 dB / km in termini di differenza di media e deviazione standard rispettivamente e la differenza RMSE è compresa tra 1,5 se si considera che rappresenta il confronto delle misurazioni effettive sull'evento base con un modello statistico basato sui dati di due siti. Le prestazioni del lavoro proposto sono eccellenti nel riprodurre condizioni di visibilità moderate in presenza di nebbia (con un'accuratezza dell'88,88%), è stata rilevata pioggia (precisione del 100%). Nel caso di Milano e Praga, il modello completo di generazione della serie di attenuazione sintetica è applicabile e fornisce ottimi risultati. Sfortunatamente, considerando Milesovka, funziona solo sulla generazione delle serie temporali di attenuazione a dissolvimento lento poiché le misurazioni erano di bassa frequenza di campionamento che non ci consente di identificare variazioni veloci. La procedura proposta può essere applicata in linea di massima a qualsiasi posizione, purché siano disponibili serie temporali di visibilità (molto semplici e poco costose da raccogliere) in cui è necessario il collegamento ottico per l'installazione.FREE Space Optical (FSO) communication is one of the most widely researched technology due to its very interesting characteristics such as high data rate, free license, no electromagnetic interference, light weight, small volume, secure due to narrow laser beam, portability, and low power consumption. However, some limitations due to weather dependency occur which include scattering and absorption, caused by gases and various hydrometers, fog being the most challenging issue which majorly impact on the performance of the FSO link.
From the application perspective, we know that in order to provide 5G technology opportunity to users to utilize extremely large bandwidth need the use of a dense network with mini base stations at short range (few 100 meters) which could be connected in two ways i.e. wired or wireless. Solving backhaul connectivity is critical before any 5G small cell deployments can scale up. There is no way to even consider adding wired backhaul drops to thousands of sites in an urban environment which will be expensive require more time and physical efforts. In this respect, FSO links can handle the scale, they are easy to deploy, very large capacity and represent an economic solution over a distance of 100 meters. It is essential that operators planning for high density small cell deployment seriously consider FSO as an option before 5G rollouts begin. In order to use FSO for backhauling, our proposed work is very useful in providing the methodology to generate synthetic attenuation values of signal fading and its characteristics over different low visibility conditions even before the deployment.
This research work is directed to propose a procedure for a synthetic attenuation time series synthesizer for low visibility events along terrestrial free space optical links useful for 5G backhauling networks design. To this aim, preprocessing for correct use of data had been done which includes identifying the low visibility events with optimal approach, bias removal on average and event basis, and identifying the best time integration value for all three databases. Later, it is demonstrated that visibility is suitable to derive attenuation time series on a slow time sampling but for fast time sampling, a general statistical technique is proposed. After doing an extensive literature, we selected a procedure for the development of a time series synthesizer among the ones proposed for mm wave and modified the procedure with the introduction of visibility time series at the input instead of using large set of attenuation time series. Also, fast variations obtained through the statistical technique will be superposed to slow fading which made the predicted synthetic attenuation time series more accurate. Finally, after executing detailed step by step procedure, synthetic attenuation time series is constituted by a synthetic component (Fast Fading) each superposed to a component obtained by manipulating measured data (Slow Fading).
Large database of measured data collected at Politecnico di Milano and in other two experimental sites of the Europe are considered to validate the proposed work. We tested our procedure on all the events from the different sites and compared synthetic time series attenuation with the measured one on a statistical basis. This testing is based on number of indicators: mean value, standard deviation and RMSE. Overall, we found an excellent result as 88.88% events have 1 dB/km and 0.5 dB/km in terms of difference in mean and standard deviation respectively and RMSE difference is within the 1.5 when considering that it represents the comparison of actual measurements on event basis with a statistical model based on the data from two sites. The performance of the proposed work is excellent in reproducing moderate visibility conditions in the presence of fog (with 88.88% accuracy), rain (100% accuracy) is found. In the case of Milan and Prague, the full model of generating the synthetic attenuation series is applicable and it gives very good results. Unfortunately, considering Milesovka, it works only on generating the slow fading attenuation time series because the measurements were of low sampling rate which doesn’t allow us to identify fast variations. The proposed procedure can be in principle applied to any location provided visibility time series (very simple and inexpensive to collect) are available where the optical link is required to set up.DIPARTIMENTO DI ELETTRONICA, INFORMAZIONE E BIOINGEGNERIATelecommunications30GENTILI, GIAN GUIDOPERNICI, BARBAR
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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