651 research outputs found
Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges
With the rapid development of marine activities, there has been an increasing
number of maritime mobile terminals, as well as a growing demand for high-speed
and ultra-reliable maritime communications to keep them connected.
Traditionally, the maritime Internet of Things (IoT) is enabled by maritime
satellites. However, satellites are seriously restricted by their high latency
and relatively low data rate. As an alternative, shore & island-based base
stations (BSs) can be built to extend the coverage of terrestrial networks
using fourth-generation (4G), fifth-generation (5G), and beyond 5G services.
Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs.
Despite of all these approaches, there are still open issues for an efficient
maritime communication network (MCN). For example, due to the complicated
electromagnetic propagation environment, the limited geometrically available BS
sites, and rigorous service demands from mission-critical applications,
conventional communication and networking theories and methods should be
tailored for maritime scenarios. Towards this end, we provide a survey on the
demand for maritime communications, the state-of-the-art MCNs, and key
technologies for enhancing transmission efficiency, extending network coverage,
and provisioning maritime-specific services. Future challenges in developing an
environment-aware, service-driven, and integrated satellite-air-ground MCN to
be smart enough to utilize external auxiliary information, e.g., sea state and
atmosphere conditions, are also discussed
Upgrading the Power Grid Functionalities with Broadband Power Line Communications: Basis, Applications, Current Trends and Challenges
This article reviews the basis and the main aspects of the recent evolution of Broadband Power Line Communications (BB-PLC or, more commonly, BPL) technologies. The article starts describing the organizations and alliances involved in the development and evolution of BPL systems, as well as the standardization institutions working on PLC technologies. Then, a short description of the technical foundation of the recent proposed technologies and a comparison of the main specifications are presented; the regulatory activities related to the limits of emissions and immunity are also addressed. Finally, some representative applications of BPL and some selected use cases enabled by these technologies are summarized, together with the main challenges to be faced.This work was financially supported in part by the Basque Government under the grants IT1426-22, PRE_2021_1_0006, and PRE_2021_1_0051, and by the Spanish Government under the grants PID2021-124706OB-I00 and RTI2018-099162-B-I00 (MCIU/AEI/FEDER, UE, funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”)
Exploring Carrier Sense Multiple Access with Collision Avoidance Techniques for Resource Sharing in Broadband Power Line Communications
A resource sharing in power line communications (PLC) for the home network is restricted by the channel assignment techniques which decide who has the right to gain access to send data. The channel assignment techniques include contention-free and contention-based. The former requires high synchronization due to the deterministic round-trip time. Besides, contention-based utilizes CSMA/CA techniques that allow stations in a network to compete for channel access and are suitable for decentralized network topology. However, a trade-off exists between the number of stations required to gain access versus system efficiency. Whilst some research has been carried out on CSMA/CA resource sharing techniques that allow only one user to transmit, there is very little work done on multiuser access to optimize system efficiency and reduce collisions in a network. The purpose of the current study was to review the CSMA/CA techniques for resource sharing to improve system efficiency in power line communications. In carrying out this study, a systematic literature review methodology to evaluate different related works and determine the most suitable approach to allow multiuser channel access was used. The study further demonstrated the impact multichannel access has on system efficiency. In addition, the study provides recommendations for future research.
Keywords: CSMA/CA; Medium access control; OFDMA; power line; resource sharing
Characterizing the Energy Trade-Offs of End-to-End Vehicular Communications using an Hyperfractal Urban Modelling
We characterize trade-offs between the end-to-end communication delay and the
energy in urban vehicular communications with infrastructure assistance. Our
study exploits the self-similarity of the location of communication entities in
cities by modeling them with an innovative model called "hyperfractal". We show
that the hyperfractal model can be extended to incorporate road-side
infrastructure and provide stochastic geometry tools to allow a rigorous
analysis. We compute theoretical bounds for the end-to-end communication hop
count considering two different energy-minimizing goals: either total
accumulated energy or maximum energy per node. We prove that the hop count for
an end-to-end transmission is bounded by where
is the fractal dimension of the mobile nodes process.
This proves that for both constraints the energy decreases as we allow choosing
routing paths of higher length. The asymptotic limit of the energy becomes
significantly small when the number of nodes becomes asymptotically large. A
lower bound on the network throughput capacity with constraints on path energy
is also given. We show that our model fits real deployments where open data
sets are available. The results are confirmed through simulations using
different fractal dimensions in a Matlab simulator
Reliable indoor power line communication systems: via application of advanced relaying processing
In this thesis, we focus on improving the performance of indoor power line communication (PLC) systems using relaying schemes. A method of modelling relay-involved PLC channels has been proposed. We study the optimal joint transceiver and relay power allocation problem for relay-assisted multicarrier indoor PLC systems. We transform the nonconvex problem into a group of sub-problems which can be efficiently solved using standard convex optimization techniques. The proposed schemes outperform conventional direct PLC systems
Industry 4.0: Industrial IoT Enhancement and WSN Performance Analysis
L'abstract è presente nell'allegato / the abstract is in the attachmen
Analysis, evaluation and improvement of RT-WMP for real-time and QoS wireless communication: Applications in confined environments
En los ultimos años, la innovación tecnológica, la característica de flexibilidad y el rápido despligue de las redes inalámbricas, han favorecido la difusión de la redes móviles ad-hoc (MANETs), capaces de ofrecer servicios para tareas específicas entre nodos móviles. Los aspectos relacionados al dinamismo de la topología móvil y el acceso a un medio compartido por naturaleza hacen que sea preciso enfrentarse a clases de problemas distintos de los relacionados con la redes cableadas, atrayendo de este modo el interés de la comunidad científica. Las redes ad-hoc suelen soportar tráfico con garantía de servicio mínimo y la mayor parte de las propuestas presentes en literatura tratan de dar garantías de ancho de banda o minimizar el retardo de los mensajes. Sin embargo hay situaciones en las que estas garantías no son suficientes. Este es el caso de los sistemas que requieren garantías mas fuertes en la entrega de los mensajes, como es el caso de los sistemas de tiempo real donde la pérdida o el retraso de un sólo mensaje puede provocar problemas graves. Otras aplicaciones como la videoconferencia, cada vez más extendidas, implican un tráfico de datos con requisitos diferentes, como la calidad de servicio (QoS). Los requisitos de tiempo real y de QoS añaden nuevos retos al ya exigente servicio de comunicación inalámbrica entre estaciones móviles de una MANET. Además, hay aplicaciones en las que hay que tener en cuenta algo más que el simple encaminamiento de los mensajes. Este es el caso de aplicaciones en entornos subterráneos, donde el conocimiento de la evolución de propagación de la señal entre los diferentes nodos puede ser útil para mejorar la calidad de servicio y mantener la conectividad en cada momento. A pesar de ésto, dentro del amplio abanicos de propuestas presente en la literatura, existen un conjunto de limitaciones que van de el mero uso de protocolos simulados a propuestas que no tienen en cuenta entornos no convencionales o que resultan aisladas desde el punto de vista de la integración en sistemas complejos. En esta tesis doctoral, se propone un estudio completo sobre un plataforma inalámbrica de tiempo real, utilizando el protocolo RT-WMP capaz de gestionar trafíco multimedia al mismo tiempo y adaptado al entorno de trabajo. Se propone una extensión para el soporte a los datos con calidad de servicio sin limitar las caractaristícas temporales del protocolo básico. Y con el fin de tener en cuenta el efecto de la propagación de la señal, se caracteriza el entorno por medio de un conjunto de restricciones de conectividad. La solución ha sido desarrollada y su validez ha sido demostrada extensamente en aplicaciones reales en entornos subterráneos, en redes malladas y aplicaciones robóticas
Cooperative Relaying In Power Line Environment: A Survey and Tutorial
Exchange of information is essential in any society and the demand for faster, cheaper, and secure
communications is increasing every day. With other hi-tech initiatives like IPv6 and Internet-of-Things (IOT) already
in the horizon, demand for broadband is set to escalate beyond its current level. Inherently laden in the challenges
posed by this technology are fresh opportunities in terms of penetration of data services into rural communities and
development of innovative strategies for more efficient use of the grid. Though still in its developmental phase/stage,
Power Line Communication (PLC) has grown beyond theoretical fantasy to become a reality. The proofs are the
readily available PLC systems that can be purchased off the shelfto achieve in-house networking and the much talked
about, smart metering technology; generally regarded as the “new bride” in utilities industry. One of the biggest gains
of PLC is its use of existing electrical cables, thereby eliminating cost of installation and maintenance of data cables.
However, given that the power infrastructure was traditionally built to deliver electricity, data signals do suffer various
forms of distortions and impairments as they transit it. This paper presents a tutorial on the deployed wireless system
technique which is to be adapted to PLC scenario for the purpose of managing the available source energy for
achieving reliable communication system. One of these techniques is the cooperative diversity. Its application and
deployment in power line environment is explored. The improvement achieved through cooperative diversity in some
PLC systems were presented along with the associated limitations. Finally, future areas of research which will further
improve the reliability of PLC systems and reduce its power consumption during transmission is shown
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