Search results for "Networks"
showing 10 items of 3260 documents
Indoor localization using time difference of arrival with UWB signals and unsynchronized devices
2020
Abstract Indoor location using radio frequency (RF) signals has been traditionally focused mainly on RSSI and fingerprint techniques, because methods based on time of arrival (ToA) or time difference of arrival (TDoA) were not suitable for measuring short distances. However, the release of the IEEE 802.15.4a standard, the emergence of commercial ultra wide band (UWB) transceivers that are compliant to this norm and the integration of high frequency oscillators have permitted the design of more accurate indoor localization systems using the RF signal transmission time. In this paper, we propose an indoor localization system based on TDoA for UWB. The method implements an only one way transmi…
A study of LoRaWAN protocol performance for IoT applications in smart agriculture
2020
Abstract The use of Internet of Things (IoT) is becoming increasingly common in agribusiness to increase food production capacity for the expanding global population. Recently, low-power wide-area networks (LPWANs) have been used in the development of IoT applications that require low power consumption and low data transmission rates. LoRaWAN is considered the most suitable communication network for LPWANs for IoT applications in smart agriculture. In this paper, we present an in-depth study of the performance of the LoRaWAN communication network in the context of an IoT application for a pilot farm. We consider several scenarios and analyze simulation results by using Network Simulator 3. …
Design and performance evaluation of an hybrid reservation-polling MAC protocol for power-line communications
2003
This paper presents an hybrid reservation-polling MAC protocol able to effectively deal with the channel disturbances typical of Power-line communication systems. Channel access is controlled by a scheduler running on a centralized station. Fast retransmission of corrupted packets is employed to achieve high performance on Power-line channels characterized by frequent error bursts due to impulsive noise. The performance of our proposed mechanism are evaluated by means of simulation, for the more challenging case of time-sensitive traffic sources (voice calls). Results show that the system efficiency is virtually not affected by lightly to moderately disturbed PLC channel. Moreover, by sligh…
Resource allocation for clustered network MIMO OFDMA systems
2012
In this article, we address the resource allocation problem for the downlink of a large network multiple input multiple output orthogonal frequency division multiplexing system with 3-sector base stations. The system is statically divided into a number of disjoint clusters of sectors. A two-step resource allocation scheme is proposed involving the inter-cluster and the intra-cluster levels. As a first step or inter-cluster level, two cooperative frequency reuse approaches are designed to mitigate the inter-cluster interference. A user partition method is proposed to divide the users of each cluster into cluster-edge and cluster-center users. To balance the cell-edge and the cell-average per…
Energy-Efficient and Secure Resource Allocation for Multiple-Antenna NOMA with Wireless Power Transfer
2018
Non-orthogonal multiple access (NOMA) is considered as one of the promising techniques for providing high data rates in the fifth generation mobile communication. By applying successive interference cancellation schemes and superposition coding at the NOMA receiver, multiple users can be multiplexed on the same subchannel. In this paper, we investigate resource allocation algorithm design for an OFDM-based NOMA system empowered by wireless power transfer. In the considered system, users who need to transmit data can only be powered by the wireless power transfer. With the consideration of an existing eavesdropper, the objective is to obtain secure and energy efficient transmission among mul…
Visiones sobre la gamificación como estrategia metodológica inclusiva en educación primaria
2022
La aparición en las últimas décadas de metodologías más activas y cooperativas parece estar dando respuesta a algunas de las necesidades del alumnado actual, mucho más diverso y digitalizado. Entre las estrategias metodológicas, este trabajo se ha centrado en la gamificación, en analizar la percepción que tiene el alumnado, el profesorado y las familias sobre cómo esta práctica puede favorecer la creación de entornos educativos más inclusivos y colaborativos. Se presenta un estudio etnográfico llevado a cabo en un centro educativo de la Comunitat Valenciana, seleccionado intencionadamente por sus especiales características instrumentales. Las técnicas de recogida de información comprenden: …
Efectos del uso de dispositivos de realidad virtual sobre el control postural y el cybersickness en jóvenes universitarios
2021
espanolEl objetivo principal de este estudio fue analizar los efectos de jugar con sistemas de realidad virtual sobre el control postural y el cybersickness. La muestra del estudio estaba compuesta por 21 sujetos de 18 a 30 anos de edad. Todos los sujetos jugaron con un dispositivo de realidad virtual durante 30 minutos. Ademas, todos los sujetos realizaron dos pretest (30 minutos e inmediatamente antes de la prueba) y dos postest (inmediatamente y 30 minutos despues de la prueba). El control postural estatico con ojos abiertos y cerrados y el cybersickness fueron evaluados en todas las pruebas. Los resultados mostraron diferencias significativas entre el pretest 2 y el postest 1 en tres de…
Introducción del sistema PECS para la superación de las limitaciones comunicativas en un caso de síndrome de West
2016
En este estudio de caso se aborda la intervención realizada en una alumna de cuatro años, escolarizada en un aula específica de un centro ordinario, y a la que recientemente han diagnosticado síndrome de West. Aplicando, a lo largo de un trimestre en un aula de Audición y Lenguaje, el sistema de comunicación por intercambio de imágenes (PECS) se pretende superar las graves limitaciones comunicativas de la alumna. El procedimiento metodológico utilizado es mixto y las técnicas de investigación empleadas son la aplicación de test estandarizados, la entrevista, los cuestionarios, los registros de observaciones y el análisis documental. A partir del test que establece la evaluación inicial del …
Seeking Information on Social Commerce: An Examination of the Impact of User- and Marketer-generated Content Through an Eye-tracking Study
2021
Following the growing popularity of social commerce sites, there is an increased interest in understanding how consumers decide what products to purchase based on the available information. Consumers nowadays are confronted with the task of assessing marketer-generated (MGC) as well as user-generated information (UGC) in a range of different forms to make informed purchase-related decisions. This study examines the information types and forms that influence consumers in their decision-making process on social commerce. Building on uses and gratifications and dual-process theories, we distinguish between marketer and user generated content, and differentiate formats into informational and no…
Acoustic spectral hole-burning in a two-level system ensemble
2020
AbstractMicroscopic two-level system (TLS) defects at dielectric surfaces and interfaces are among the dominant sources of loss in superconducting quantum circuits, and their properties have been extensively probed using superconducting resonators and qubits. We report on spectroscopy of TLSs coupling to the strain field in a surface acoustic wave (SAW) resonator. The narrow free spectral range of the resonator allows for two-tone spectroscopy where a strong pump is applied at one resonance, while a weak signal is used to probe a different mode. We map the spectral hole burnt by the pump tone as a function of frequency and extract parameters of the TLS ensemble. Our results suggest that det…