DCO-OFDM Signals With Derated Power for Visible Light Communications Using an Optimized Adaptive Network-Based Fuzzy Inference System

Direct current-biased optical orthogonal frequency division multiplexing (DCO-OFDM) signals used in visible light communications suffer from high peak-to-average-power ratio (PAPR) or cubic metric (CM). It strongly degrades the performance due to the great back-off necessary to avoid the clipping effect in the light-emitting diode. Thus, PAPR and CM reduction techniques become crucial to improve the system performance. In this paper, an adaptive network-based fuzzy inference system (ANFIS) is used to obtain efficient DCO-OFDM signals with a low power envelope profile. First, signals specially designed for DCO-OFDMwith very low CM, as the ones obtained from the raw cubic metric (RCM)-active constellation extension method, are used to train the fuzzy systems in time and frequency domains. Second, after the off-line training, the ANFIS can generate a real-valued signal in a one-shot way with 8.9 dB of RCM reduction from the original real-valued signal, which involves a gain in the input power back off larger than 2.8 dB, an illumination-to-communication conversion efficiency gain of more than 35% and considerable improvements in bit error rate

Effect of graphene on the fracture behaviour of 3D printed PLA SENB specimens

ABSTRACT: This paper analyses the effect of graphene addition on the fracture behaviour of 3D printed PLA SENB specimens containing crack-like defects. The addition of graphene is assumed to improve the tensile behaviour of 3D printed PLA material, but the integrity of structural components strongly depends on the material fracture resistance. Tensile and fracture SENB specimens have been tested with different raster orientations (0/90, 30/-60 and 45/-45), showing that the effect of graphene addition (1 wt. %) is very sensitive to the raster orientation: this effect is significant for raster orientation 45/-45 and very limited for 0/90 (with 30/-60 providing intermediate results).The authors of this work would like to express their gratitude to the Spanish Ministry of Science and Innovation for the financial support of the project PGC2018-095400-B-I00 “Comportamiento en fractura de materiales compuestos nano-reforzados con defectos tipo entalla”

Elaboración de un manual de procedimientos para la certificación de redes pasivas de fibra óptica

En el presente trabajo de investigación, se analizan primeramente todos los aspectos teóricos involucrados en red óptica pasiva, tales como topologías, tipos de fibras, elementos de una red óptica pasiva, tipos de pérdidas y eventos presentes en las mismas, lo cual constituye la base para la elaboración del manual en sí. A continuación, se describen los tipos de pruebas que se realizan para certificar las redes ópticas pasivas así como los equipos necesarios. Descrita la teoría base, los tipos de pruebas y los equipos, se procede con el desarrollo detallado de los procedimientos para la certificación, así como de las guías para detección y solución de daños, correlacionando dichos procedimientos y guías con normas internacionales afines a nuestro trabajo y con la recomendación de los fabricantes de equipos de certificación. Finalmente, se expone un caso práctico de aplicación en el cual se aplican muchos de los criterios, procedimientos y guías descritos

Diseño de un laboratorio virtual de telefonía IP utilizando Elastix.

En la última década la telefonía IP ha alcanzado un gran desarrollo a nivel mundial debido a las ventajas económicas que esta trae consigo, ventajas estas que ha llevado a muchos a cuestionarse por el futuro de la telefonía tradicional. La idea fundamental de este trabajo de investigación es implementar una central telefónica IP bajo la distribución de software libre Elastix. Esta central telefónica y el analizador de protocolo Wireshark y softphones se utilizarán en el laboratorio de telecomunicaciones de la Facultad de Educación Técnica para el Desarrollo y permitirá a los estudiantes de la carrera poner en práctica los conocimientos adquiridos en las clases teóricas

Lights and Shadows: A Comprehensive Survey on Cooperative and Precoding Schemes to Overcome LOS Blockage and Interference in Indoor VLC

Visible light communications (VLC) have received significant attention as a way of moving part of the saturated indoor wireless traffic to the wide and unregulated visible optical spectrum. Nowadays, VLC are considered as a suitable technology, for several applications such as high-rate data transmission, supporting internet of things communications or positioning. The signal processing originally derived from radio-frequency (RF) systems such as cooperative or precoding schemes can be applied to VLC. However, its implementation is not straightforward. Furthermore, unlike RF transmission, VLC present a predominant line-of-sight link, although a weak non-LoS component may appear due to the reflection of the light on walls, floor, ceiling and nearby objects. Blocking effects may compromise the performance of the aforementioned transmission schemes. There exist several surveys in the literature focused on VLC and its applications, but the management of the shadowing and interference in VLC requires a comprehensive study. To fill this gap, this work introduces the implementation of cooperative and precoding schemes to VLC, while remarking their benefits and drawbacks for overcoming the shadowing effects. After that, the combination of both cooperative and precoding schemes is analyzed as a way of providing resilient VLC networks. Finally, we propose several open issues that the cooperative and precoding schemes must face in order to provide satisfactory VLC performance in indoor scenarios.This work has been supported partially by Spanish National Project TERESA-ADA(TEC2017-90093-C3-2-R) (MINECO/AEI/FEDER, UE), the research project GEOVEOLUZ-CM-UC3Mfunded by the call “Programa de apoyo a la realización de proyectos interdisciplinares de I+D parajóvenes investigadores de la Universidad Carlos III de Madrid 2019-2020” under the frame ofthe Convenio Plurianual Comunidad de Madrid-Universidad Carlos III de Madrid and projectMadrid Flight on Chip (Innovation Cooperative Projects Comunidad of Madrid - HUBS 2018/MadridFlightOnChip). Additionally, it has been supported partially by the Juan de la CiervaIncorporación grant IJC2019-040317-I and Juan de la Cierva Formación grant (FJC2019-039541-I/AEI/10.13039/501100011033)

Investigating the deployability of VoIP services over wireless interconnected micro aerial vehicles

Emerging technological devices, such as Unmanned Aircraft Vehicles (UAV) and Single Board Computers (SBC), are being increasingly employed in recent years, thanks to the advances in electronics and the wide variety of sensors that are endowed. This paper aims at analyzing the viability of deploying multimedia services, focusing on the voice scenario, over wireless interconnected Micro Air Vehicles (MAV), also known as drones. Toward this end, we assessed the performance both of the embedded wireless cards of current drones and also SBCs, which may be carried as payload in existing UAV solutions. Driven by the results obtained in these experiments, we then deployed an operational VoIP service over a network of commercial MAVs, to perform an experimental analysis on the resource capabilities of these devices and demonstrate that this type of service can certainly be used.This article has been partially supported by the European H2020 5GinFIRE project (grant agreement 732497) and the 5G‐City project (TEC2016‐76795‐C6‐3‐R) funded by the Spanish Ministry of Economy and Competitiveness

Flexible services deployment using Small Unmanned Aerial Vehicles for emergency situations

Proceeding of: XXXIII Simposium Nacional de la Unión Científica Internacional de Radio (URSI 2018), 5-7 de septiembre de 2018, Granada, España.The notorious advances in the Unmanned Aerial Vehicles (UAV) research area is allowing small UAVs (SUAV) to have an increasing presence in different civil applications. In the context of the 5GCity Spanish coordinated project, this paper considers the use of SUAV networks to support emergency services in critical and disaster situations. To solve the set of challenges presented in UAV networks, we present a general use case with the deployment of an NFV and SDN based solution and the different key enabling technologies. The whole deployment will be split into three stages during the project lifetime, with an initial integration using the 5TONIC European Open Research 5G laboratory and then with the different 5GCity project partners.This article has been partially supported by the 5G-City project (TEC2016-76795-C6-3-R) funded by the Spanish Ministry of Economy and Competitiveness.No publicad

Adaptable and automated small UAV deployments via virtualization

In this paper, we present a practical solution to support the adaptable and automated deployment of applications of Small Unmanned Aerial Vehicles (SUAVs). Our solution is based on virtualization technologies, and considers SUAVs as programmable network platforms capable of executing virtual functions and services, which may be dynamically selected according to the requirements specified by the operator of the aerial vehicles. This way, SUAVs can be flexibly and rapidly adapted to different missions with heterogeneous objectives. The design of our solution is based on Network Function Virtualization (NFV) technologies, developed under the umbrella of the fifth generation of mobile networks (5G), as well as on existing Internet protocol standards, including flying ad hoc network routing protocols. We implemented a functional prototype of our solution using well-known open source technologies, and we demonstrated its practical feasibility with the execution of an IP telephony service. This service was implemented as a set of virtualized network functions, which were automatically deployed and interconnected over an infrastructure of SUAVs, being the telephony service tested with real voice-over-IP terminals.This article was partially supported by the European H2020 5GinFIRE project (grant agreement 732497), and by the 5GCity project (TEC2016-76795-C6-3-R) funded by the Spanish Ministry of Economy and Competitiveness

The Pygmalion Effect in Teaching Practice

El efecto Pigmalión se refiere a que la expectativa que tiene una persona sobre otra puede llegar a influir en el rendimiento de dicho sujeto. Este efecto tiene influencia sobre la autoestima, el rendimiento, las actitudes, la motivación y los comportamientos del alumnado. Tiene una doble dirección y nos obliga a ser conscientes de la importancia de mostrarle a un alumno confianza y expectativas de éxito en sus tareas para que trate de hacer realidad las esperanzas que se han depositado en él. Nuestra labor es vital para lograr alumnos con autoconcepto positivo que puedan enfrentarse a los retos educativos.The Pygmalion effect refers to the belief or expectation that one person has over another can influence the performance of that subject. This effect has an influence on students' self-esteem, performance, attitudes, motivation and behaviors. It also has a double direction and forces us to be aware of the importance of showing a student confidence and expectations of success in their tasks so that he tries to realize the hopes that have been placed in him. Our work is vital to achieve students with positive self-concept who can cope with the various educational challenges

Learning Mobile Communications Standards through Flexible Software Defined Radio Base Stations

Mobile communications are today widespread and contribute to the development of our society. Every day new devices include some means of wireless transmission, which is becoming ubiquitous with the Internet of Things. These systems are standardized by international organizations such as the IEEE, 3GPP, and ETSI, among others. Even though knowledge of wireless standards is key to the understanding of these systems, wireless communications are quite often taught in engineering degrees in a traditional way, without much emphasis on the standardization. Moreover, strong focus is often placed on the theoretical performance analysis rather than on practical implementation aspects. In contrast, most of the current applications make extensive use of mobile data, and the global users' satisfaction is highly correlated with the mobile data throughput. Thus, modern wireless engineers need to have deep insight on the standards that define the mobile transmission systems, and this knowledge is not acquired following the traditional theoretical teaching schemes. In this article, a new learning approach is described. This novel paradigm is based on a new flexible hardware/software platform (FRAMED-SOFT), which is also detailed. Although the article is focused on two wireless standards, GSM and UMTS, the work discussed in this article can easily be extended to other standards of interest, such as LTE and beyond, WiFi, and WiMAX