Evaluating the Use of QoS for Video Delivery in Vehicular Networks

In a near future, video transmission capabilities in intelligent vehicular networks will be essential for deploying high-demanded multimedia services for drivers and passengers. Applications and services like video on demand, iTV, context-aware video commercials, touristic information, driving assis-tance, multimedia e-call, etc., will be part of the common multimedia service-set of future transportation systems. However, wireless vehicular networks introduce several constraints that may seriously impact on the final quality of the video content delivery process. Factors like the shared-medium communication model, the limited bandwidth, the unconstrained delays, the signal propagation issues, and the node mobility, will be the ones that will degrade video delivery performance, so it will be a hard task to guarantee the minimum quality of service required by video applications. In this work, we will study how these factors impact on the received video quality by using a detailed simulation model of a urban vehicular network scenario. We will apply different techniques to reduce the video quality degradation produced by the transmission impairments like (a) Intra-refresh video coding modes, (b) frame partitioning (tiles/slices), and (c) quality of service at the Medium Access Control (MAC) level. So, we will learn how these techniques are able to fight against the network impairments produced by the hostile environment typically found in vehicular network scenarios. The experiments were carried out with a simulation environment based on the OMNeT++, Veins and SUMO simulators. Results show that the combination of the proposed techniques significantly improves the robustness of video transmission in vehicular networks, paving the way, with a wise collaboration with other techniques, to achieve a robust video delivery system that supports multimedia applications in future intelligent transportation systems

A Simulation Tool for Evaluating Video Streaming Architectures in Vehicular Network Scenarios

An integrated simulation tool called Video Delivery Simulation Framework over Vehicular Networks (VDSF-VN) is presented. This framework is intended to allow users to conduct experiments related to video transmission in vehicular networks by means of simulation. Research on this topic requires the use of many independent tools, such as traffic and network simulators, intermediate frameworks, video encoders and decoders, converters, platform-dependent scripting languages, data visualisation packages and spreadsheets, and some other tasks are performed manually. The lack of tools necessary to carry out all these tasks in an integrated and efficient way formed the motivation for the development of the VDSF-VN framework. It is managed via two user-friendly applications, GatcomSUMO and GatcomVideo, which allow all the necessary tasks to be accomplished. The first is primarily used to build the network scenario and set up the traffic flows, whereas the second involves the delivery process of the whole video, encoding/decoding video, running simulations, and processing all the experimental results to automatically provide the requested figures, tables and reports. This multiplatform framework is intended to fill the existing gap in this field, and has been successfully used in several experimental tests of vehicular network

Simulation Framework for Evaluating Video Delivery Services over Vehicular Networks

Vehicular Ad-hoc Networks contribute to the Intelligent Transportation Systems by providing a set of services related to traffic, mobility, safe driving, and infotainment applications. One of the most challenging applications is video delivery, since it has to deal with several hurdles typically found in wireless communications, like high node mobility, bandwidth limitations and high loss rates. In this work, we propose an integrated simulation framework that will provide a multilayer view of a particular video delivery session with a bunch of simulation results at physical (i.e., collisions), MAC (i.e., packet delay), application (i.e.,%of lost frames), and user levels (i.e., perceptual video quality). With this tool, we can analyze the performance of video streaming over vehicular networks with a high level of detail, giving us the keys to better understand and, as a consequence, improve video delivery services

Biomass and primary production of a 8-11 m depth meadow versus <3 m depth meadows of the seagrass Cymodocea nodosa (Ucria) Ascherson

Current knowledge about the abundance, growth, and primary production of the seagrass Cymodocea nodosa (Ucria) Ascherson is biased towards shallow (depth <3 m) meadows although this species also forms extensive meadows at larger depths along the coastlines. The biomass and primary production of a C. nodosa meadow located at a depth of 8-11 m was estimated at the time of maximum annual vegetative development (summer) using reconstruction techniques, and compared with those available from shallow meadows of this species. A depth-referenced data base of values at the time of maximum annual development was compiled to that end. The vegetative development of C. nodosa at 8-11 m depth was not different from that achieved by shallow (depth <3 m) meadows of this species. Only shoot density, which decreased from 1637 to 605 shoots m-2, and the annual rate of elongation of the horizontal rhizome, which increased from 23 to 71 cm apex-1 year-1, were different as depth increased from <3 to 8-11 m. Depth was a poor predictor of the vegetative development and primary production of C. nodosa. The biomass of rhizomes and roots decreased with depth (g DW m-2 = 480 (±53, S.E.) - 32 (±15, S.E.) depth (in m); R2 = 0.12, F = 4.65, d.f. = 35, P = 0.0381) which made total biomass of the meadow to show a trend of decrease with depth but the variance of biomass data explained by depth was low. The annual rate of elongation of the horizontal rhizome showed a significant positive relationship with depth (cm apex-1 year-1 = 18 (±5.1, S.E.) + 5.0 (±1.33, S.E.) depth (in m); R2 = 0.50, F = 14.07, d.f. = 14, P = 0.0021). As shoot size and growth did not change significantly with depth, the reduction of shoot density should drive any changes of biomass and productivity of C. nodosa as depth increases. The processes by which this reduction of C. nodosa abundance with depth occur remain to be elucidated. © 2006 Elsevier B.V. All rights reserved.This study was funded by the Specific Programme “Energy, Environment and Sustainable Development” of the Fifth Framework Programme of the European Union (contract number EVK3-CT-2000-00044, Monitoring and Managing of European Seagrass Beds)Peer Reviewe

Seguimiento del paciente convaleciente de Covid-19 con oxigenoterapia domiciliaria provisional a partir de un caso clínico

Introducción: la covid-19 es una enfermedad que está generando gran impacto a nivel psicosocial y una vez superada la fase aguda de la enfermedad pueden permanecer ciertos síntomas como insuficiencia respiratoria, astenia, dolor de pecho, entre otros, por lo que un pequeño porcentaje de pacientes requieren de oxigenoterapia domiciliaria de forma provisional a bajo flujo según la gravedad del cuadro.Objetivo: Minimizar el impacto originado por la COVID-19 y su tratamiento con el fin de facilitar la adherencia terapéutica al mismo.Metodología: Se utilizaron diversas bases de datos científicas y páginas web oficiales para realizar una revisión bibliográfica del tema. Además, se consultó la página web “NNNConsult” para el desarrollo del Proceso de Atención Enfermera.Conclusión: Tras superar la fase aguda de la COVID-19, es importante realizar un seguimiento ambulatorio de los pacientes ya que se trata de un grupo muy vulnerable. El porcentaje de pacientes que vuelven al domicilio con oxigenoterapia provisional es muy reducido y el impacto emocional que sufren es mayor a lo habitual. Por ello, reforzando los conocimientos transmitidos al alta y realizando un seguimiento a nivel psicosocial se puede lograr un mejor afrontamiento de la enfermedad, una mejor adherencia al tratamiento así como una recuperación precoz. Palabras clave: oxigenoterapia domiciliaria, impacto emocional, convalecencia covid-19, atención primaria, síntomas post-covid-19.<br /

Optimizing the Transmission of Multimedia Content over Vehicular Networks

The multi channel operation mechanism of the IEEE 1609.4 protocol, used in vehicular networks, may impact network performance if applications do not care about its details. Packets delivered from the application layer to the MAC layer during a Control Channel time slot have to wait to be transmitted until the following Service Channel time slot arrives. The accumulation of packets at the beginning of this time slot may introduce additional delays and higher collision rates when packets are transmitted. In this work we propose a method, which we call SkipCCH, that deals with this issue in order to make a better use of the wireless channel and, as a consequence, increase the overall network performance. With our proposal, streaming video in vehicular networks will provide better reconstructed quality at the receiver side under the same network conditions. Furthermore, this method has particularly proven its benefits when working with QoS techniques, not only by increasing the received video quality, but also because it avoids starvation of the lower priority traffic

Evaluating H.265 real-time video flooding quality in highway V2V environments

© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works[EN] Video transmission over VANETs is an extremely difficult task not only due to the high bandwidth requirements, but also due to typical VANET characteristics such as signal attenuation, packet losses, high relative speeds and fast topology changes. In future scenarios, vehicles will provide other vehicles with information about accidents or congestion on the road, and in these cases offering visual information can be a really valuable resource for both drivers and traffic authorities. Hence, achieving an efficient transmission is critical to maximize the user-perceived quality. In this paper we evaluate solutions that combine different flooding techniques, and different video codecs to assess the effectiveness of long-distance real-time video streaming. In particular, we will compare the most effective video coding standard available (H.264) with the upcoming H.265 codec in terms of both frame loss and PSNR.This work was partially supported by the Ministerio de Economía y Competitividad, Spain, under Grant TIN2011- 27543-C03-01, and by the Ministerio de Educación, Spain, under the FPU program, AP2009-2415.Torres Cortés, Á.; Piñol, P.; Tavares De Araujo Cesariny Calafate, CM.; Cano Escribá, JC.; Manzoni, P. (2014). Evaluating H.265 real-time video flooding quality in highway V2V environments. En 2014 IEEE Wireless Communications and Networking Conference (WCNC). IEEE. 2758-2763. https://doi.org/10.1109/WCNC.2014.6952858S2758276

Findings of intraformational striated pavements in the late carboniferous glacial deposits of the Andean Precordillera, Argentina

One of the most important glacial events in the history of the Earth took place during the Late Paleozoic when large areas of the Gondwana Supercontinent were covered by ice-masses (Crowell, 1978; Hambrey and Harland, 1981; Isbell et al., 2003a,b; Rocha Campos et al., 2008; Fielding et al., 2008; López Gamundí, 2010). Though this glacial event was initially considered a large and unique episode spanning a great part of the Carboniferous and Permian in Gondwana, new geological evidence suggests that the glacial period was not continuous, but rather punctuated by several interglacial events. In this way, López Gamundí (1997) and later Isbell et al. (2003b) divided the Late Paleozoic Ice Age (LPIA) into four major glacial intervals corresponding to the Early Carboniferous (LPIA 1), Late Carboniferous- Early Permian (LPIA 2), Early Permian (LPIA 3) and Late Permian (LPIA 4). This division adequately describes the record of the glacial deposits in Gondwana and allows for the proposal of a general stratigraphy for the glacial deposits demonstrating the existence of low-frequency climatic changes. In this paper we describe two subglacial basal contact surfaces found in the lower part of the Guandacol Formation (Frenguelli, 1944; Cuerda, 1965) in the Central Precordillera (northwestern Argentina). The Guandacol Formation is well known for containing glacial deposits, including diamictites and resedimented diamictites at the lower third of the unit (Limarino et al., 2006; Marenssi et al., 2002; Marenssi et al., 2005). According to paleontological (palynological) information, and some radiometric dating, the age of the glacial deposits is Late Visean- Early Bashkirian and therefore fits into the LPIA 2 interval of Isbell et al. (2003b)

Docencia de Semáforos y Monitores con BACI: un ejemplo de aprendizaje guiado

En este artículo se pretende recoger la experiencia realizada en la asignatura 'Sistemas Operativos' de segundo curso de Ingeniería Técnica en Informática de Gestión, impartida en la Escuela Politécnica Superior de Orihuela de la Universidad Miguel Hernández. En concreto la experiencia se ha realizado sobre la parte del temario de la asignatura que cubre los conceptos de concurrencia, exclusión mutua y sincronización de procesos. La utilización de las nuevas tecnologías no garantiza unos mejores resultados en el aprendizaje de los alumnos. Lo que sí desempeña un papel crucial en la obtención de buenos resultados es, especialmente, la forma en la que la tecnología es puesta en práctica y utilizada. Con este ejemplo proponemos una metodología para la inclusión de las nuevas tecnologías en el aula cuyos objetivos principales son intentar garantizar un buen rendimiento en las prácticas de la asignatura así como obtener una mayor motivación del alumnado, una mejor comprensión de los conceptos teóricos y un uso planificado y guiado en el proceso de enseñanza-aprendizaje. Para conseguir dichos objetivos se ha puesto en marcha, siguiendo la planificación de dicha metodología, el uso en el aula de una herramienta que simula el efecto de los semáforos, los monitores y la sincronización de procesos llamada BACI (Ben-Ari Concurrent Interpreter)

Diseñando servicios móviles en el laboratorio de redes

Se exponen las experiencias y resultados obtenidos en el desarrollo de las prácticas de asignaturas relativas a tecnologías de la información. Debido a la evolución tecnológica en los terminales y servicios de la telefonía móvil, se ha pretendido innovar en las prácticas de las asignaturas de las titulaciones de Ingeniero Técnico en Informática de Gestión (ITIG), Ingeniero Técnico de Telecomunicaciones (ITT) e Ingeniero de Telecomunicaciones (IT) de la Universidad Miguel Hernández. El principal objetivo para estas prácticas se centra en conseguir la motivación máxima por parte del alumnado y la concepción de las prácticas de una asignatura como un marco de enlace a su futuro laboral. En el presente documento se expone la globalidad del proyecto que los estudiantes han de realizar en prácticas, los requerimientos técnicos, ventajas e inconvenientes y las conclusiones a las que hemos llegado después de una breve encuesta contrastada con los resultados obtenidos en las sesiones de prácticas