1,139 research outputs found
Mobility management in 5G for high-speed trains
High-speed trains (HST) are nowadays more present in our lives currently, some of them can reach speeds up to 500 km/h and futuristic concepts such as hyperloop tunnels could make trains travel at speeds up to 1000 km/h. Dealing with such high speeds arises many communication problems, for example, in mobility management, with many handovers or high Doppler frequency shifts. You might be thinking how it is possible to provide a good QoS to the users inside the train, when traveling at such elevated velocities. In the thesis, we rely on the development of 5G New Radio and the benefits associated, such as a new handover protocol introduced by 3GPP called conditional handover (CHO). By simulating with Simu5G a HST scenario we have proved that CHO can provide a better service to the users by improving the SINR levels and being more efficient than common handover.Los trenes de alta velocidad están cada vez más presentes en nuestro dĂa a dĂa, algunos ya alcanzan velocidades de 500 km/h, mientras que otros conceptos futuristas como los tĂşneles hyperloop podrĂan hacer que alcanzaran velocidades de hasta 1000 km/h. En el ámbito de las telecomunicaciones, trabajar a tan altas velocidades conlleva algunos problemas, como por ejemplo un elevado nĂşmero de handovers. Seguramente, os estĂ©is preguntando cĂłmo es posible establecer un servicio que cumpla unos mĂnimos de calidad para el usuario, cuando este viaja a tan altas velocidades. Para ello, nos hemos apoyado en la tecnologĂa 5G i un nuevo concepto de handover llamado conditional handover (CHO), introducido por el 3GPP. A travĂ©s del simulador Simu5G, hemos conseguido demostrar que el CHO no solo es un protocolo más eficiente, sino que además conlleva una mejora en los niveles de SINR, en condiciones parecidas a las de un tren de alta velocidad.Els trens d'alta velocitat estan cada vegada mĂ©s presents en el nostre dia a dia, alguns ja son capaços d'arribar a velocitats pròximes als 500 km/h, mentre que altres conceptes futuristes com els tĂşnels hyperloop podrien fer que els trens arribessin a velocitats de 1000 km/h. En l'Ă mbit de les comunicacions, treballar amb velocitats tan elevades comporta alguns problemes, com per exemple un ampli nĂşmero de handovers. Segurament, estareu pensant com es possible establir un servei que compleixi uns mĂnims de qualitat de cara a l'usuari, al estar treballant amb velocitats tant elevades. Per fer-ho ens hem recolzat en la tecnologia 5G i un nou concepte de handover presentat pel 3GPP, el conditional handover (CHO). Simulant a travĂ©s de Simu5G un escenari similar al d'un tren d'alta velocitat, hem pogut demostrar que el CHO no es nomĂ©s un protocol mĂ©s eficient que el handover normal, sinĂł que a mĂ©s a mĂ©s millora els nivells de SINR
6G Enabled Advanced Transportation Systems
The 6th generation (6G) wireless communication network is envisaged to be
able to change our lives drastically, including transportation. In this paper,
two ways of interactions between 6G communication networks and transportation
are introduced. With the new usage scenarios and capabilities 6G is going to
support, passengers on all sorts of transportation systems will be able to get
data more easily, even in the most remote areas on the planet. The quality of
communication will also be improved significantly, thanks to the advanced
capabilities of 6G. On top of providing seamless and ubiquitous connectivity to
all forms of transportation, 6G will also transform the transportation systems
to make them more intelligent, more efficient, and safer. Based on the latest
research and standardization progresses, technical analysis on how 6G can
empower advanced transportation systems are provided, as well as challenges and
insights for a possible road ahead.Comment: Submitted to an open access journa
Integration of Data Driven Technologies in Smart Grids for Resilient and Sustainable Smart Cities: A Comprehensive Review
A modern-day society demands resilient, reliable, and smart urban
infrastructure for effective and in telligent operations and deployment.
However, unexpected, high-impact, and low-probability events such as
earthquakes, tsunamis, tornadoes, and hurricanes make the design of such robust
infrastructure more complex. As a result of such events, a power system
infrastructure can be severely affected, leading to unprecedented events, such
as blackouts. Nevertheless, the integration of smart grids into the existing
framework of smart cities adds to their resilience. Therefore, designing a
resilient and reliable power system network is an inevitable requirement of
modern smart city infras tructure. With the deployment of the Internet of
Things (IoT), smart cities infrastructures have taken a transformational turn
towards introducing technologies that do not only provide ease and comfort to
the citizens but are also feasible in terms of sustainability and
dependability. This paper presents a holistic view of a resilient and
sustainable smart city architecture that utilizes IoT, big data analytics,
unmanned aerial vehicles, and smart grids through intelligent integration of
renew able energy resources. In addition, the impact of disasters on the power
system infrastructure is investigated and different types of optimization
techniques that can be used to sustain the power flow in the network during
disturbances are compared and analyzed. Furthermore, a comparative review
analysis of different data-driven machine learning techniques for sustainable
smart cities is performed along with the discussion on open research issues and
challenges
Photochemistry in Terrestrial Exoplanet Atmospheres III: Photochemistry and Thermochemistry in Thick Atmospheres on Super Earths and Mini Neptunes
Some super Earths and mini Neptunes will likely have thick atmospheres that
are not H2-dominated. We have developed a photochemistry-thermochemistry
kinetic-transport model for exploring the compositions of thick atmospheres on
super Earths and mini Neptunes, applicable for both H2-dominated atmospheres
and non-H2-dominated atmospheres. Using this model to study thick atmospheres
for wide ranges of temperatures and elemental abundances, we classify them into
hydrogen-rich atmospheres, water-rich atmospheres, oxygen-rich atmospheres, and
hydrocarbon-rich atmospheres. We find that carbon has to be in the form of CO2
rather than CH4 or CO in a H2-depleted water-dominated thick atmosphere, and
that the preferred loss of light elements from an oxygen-poor carbon-rich
atmosphere leads to formation of unsaturated hydrocarbons (C2H2 and C2H4). We
apply our self-consistent atmosphere models to compute spectra and diagnostic
features for known transiting low-mass exoplanets GJ 1214 b, HD 97658 b, and 55
Cnc e. For GJ 1214 b like planets we find that (1) C2H2 features at 1.0 and 1.5
micron in transmission and C2H2 and C2H4 features at 9-14 micron in thermal
emission are diagnostic for hydrocarbon-rich atmospheres; (2) a detection of
water-vapor features and a confirmation of nonexistence of methane features
would provide sufficient evidence for a water-dominated atmosphere. In general,
our simulations show that chemical stability has to be taken into account when
interpreting the spectrum of a super Earth/mini Neptune. Water-dominated
atmospheres only exist for carbon to oxygen ratios much lower than the solar
ratio, suggesting that this kind of atmospheres could be rare.Comment: Accepted for publication on Ap
Circuit-Variant Moving Target Defense for Side-Channel Attacks on Reconfigurable Hardware
With the emergence of side-channel analysis (SCA) attacks, bits of a secret key may be derived by correlating key values with physical properties of cryptographic process execution. Power and Electromagnetic (EM) analysis attacks are based on the principle that current flow within a cryptographic device is key-dependent and therefore, the resulting power consumption and EM emanations during encryption and/or decryption can be correlated to secret key values. These side-channel attacks require several measurements of the target process in order to amplify the signal of interest, filter out noise, and derive the secret key through statistical analysis methods. Differential power and EM analysis attacks rely on correlating actual side-channel measurements to hypothetical models. This research proposes increasing resistance to differential power and EM analysis attacks through structural and spatial randomization of an implementation. By introducing randomly located circuit variants of encryption components, the proposed moving target defense aims to disrupt side-channel collection and correlation needed to successfully implement an attac
A Survey on Applications of Cache-Aided NOMA
Contrary to orthogonal multiple-access (OMA), non-orthogonal multiple-access (NOMA) schemes can serve a pool of users without exploiting the scarce frequency or time domain resources. This is useful in meeting the future network requirements (5G and beyond systems), such as, low latency, massive connectivity, users' fairness, and high spectral efficiency. On the other hand, content caching restricts duplicate data transmission by storing popular contents in advance at the network edge which reduces data traffic. In this survey, we focus on cache-aided NOMA-based wireless networks which can reap the benefits of both cache and NOMA; switching to NOMA from OMA enables cache-aided networks to push additional files to content servers in parallel and improve the cache hit probability. Beginning with fundamentals of the cache-aided NOMA technology, we summarize the performance goals of cache-aided NOMA systems, present the associated design challenges, and categorize the recent related literature based on their application verticals. Concomitant standardization activities and open research challenges are highlighted as well
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