21,048 research outputs found
6G Radio Testbeds: Requirements, Trends, and Approaches
The proof of the pudding is in the eating - that is why 6G testbeds are
essential in the progress towards the next generation of wireless networks.
Theoretical research towards 6G wireless networks is proposing advanced
technologies to serve new applications and drastically improve the energy
performance of the network. Testbeds are indispensable to validate these new
technologies under more realistic conditions. This paper clarifies the
requirements for 6G radio testbeds, reveals trends, and introduces approaches
towards their development
Why are glass-forming liquids non-Arrhenius?
A major mystery of glass-forming liquids is the non-Arrhenius
temperature-dependence of the average relaxation time. This paper briefly
reviews the classical phenomenological models for this phenomenon - the
free-volume model and the entropy model - and critiques against these models.
We then discuss a recent model [Dyre, Olsen, and Christensen, Phys. Rev. B 53,
2171 (1996)] according to which the activation energy for the average
relaxation time is determined by the work done in shoving aside the surrounding
liquid to create space needed for a flow event. In this model the non-Arrhenius
temperature-dependence is a consequence of the fact that the instantaneous
(infinite-frequency) shear modulus increases upon cooling.Comment: 18 pages, plain RevTex file, no figure
6G Enabled Smart Infrastructure for Sustainable Society: Opportunities, Challenges, and Research Roadmap
The 5G wireless communication network is currently faced with the challenge of limited data speed exacerbated by the proliferation of billions of data-intensive applications. To address this problem, researchers are developing cutting-edge technologies for the envisioned 6G wireless communication standards to satisfy the escalating wireless services demands. Though some of the candidate technologies in the 5G standards will apply to 6G wireless networks, key disruptive technologies that will guarantee the desired quality of physical experience to achieve ubiquitous wireless connectivity are expected in 6G. This article first provides a foundational background on the evolution of different wireless communication standards to have a proper insight into the vision and requirements of 6G. Second, we provide a panoramic view of the enabling technologies proposed to facilitate 6G and introduce emerging 6G applications such as multi-sensory–extended reality, digital replica, and more. Next, the technology-driven challenges, social, psychological, health and commercialization issues posed to actualizing 6G, and the probable solutions to tackle these challenges are discussed extensively. Additionally, we present new use cases of the 6G technology in agriculture, education, media and entertainment, logistics and transportation, and tourism. Furthermore, we discuss the multi-faceted communication capabilities of 6G that will contribute significantly to global sustainability and how 6G will bring about a dramatic change in the business arena. Finally, we highlight the research trends, open research issues, and key take-away lessons for future research exploration in 6G wireless communicatio
Z' mass limits and the naturalness of supersymmetry
The discovery of a 125 GeV Higgs boson and rising lower bounds on the masses
of superpartners have lead to concerns that supersymmetric models are now fine
tuned. Large stop masses, required for a 125 GeV Higgs, feed into the
electroweak symmetry breaking conditions through renormalisation group
equations forcing one to fine tune these parameters to obtain the correct
electroweak vacuum expectation value. Nonetheless this fine tuning depends
crucially on our assumptions about the supersymmetry breaking scale. At the
same time extensions provide the most compelling solution to the
-problem, which is also a naturalness issue, and allow the tree level
Higgs mass to be raised substantially above . These very well motivated
supersymmetric models predict a new boson which could be discovered at the
LHC and the naturalness of the model requires that the boson mass should
not be too far above the TeV scale. Moreover this fine tuning appears at the
tree level, making it less dependent on assumptions about the supersymmetry
breaking mechanism. Here we study this fine tuning for several
supersymmetric extensions of the Standard Model and compare it to the situation
in the MSSM where the most direct tree level fine tuning can be probed through
chargino mass limits. We show that future LHC searches are extremely
important for challenging the most natural scenarios in these models.Comment: 58 pages, 5 figures; typos corrected, references added; matches
version to be published in Phys. Rev.
Split Federated Learning for 6G Enabled-Networks: Requirements, Challenges and Future Directions
Sixth-generation (6G) networks anticipate intelligently supporting a wide
range of smart services and innovative applications. Such a context urges a
heavy usage of Machine Learning (ML) techniques, particularly Deep Learning
(DL), to foster innovation and ease the deployment of intelligent network
functions/operations, which are able to fulfill the various requirements of the
envisioned 6G services. Specifically, collaborative ML/DL consists of deploying
a set of distributed agents that collaboratively train learning models without
sharing their data, thus improving data privacy and reducing the
time/communication overhead. This work provides a comprehensive study on how
collaborative learning can be effectively deployed over 6G wireless networks.
In particular, our study focuses on Split Federated Learning (SFL), a technique
recently emerged promising better performance compared with existing
collaborative learning approaches. We first provide an overview of three
emerging collaborative learning paradigms, including federated learning, split
learning, and split federated learning, as well as of 6G networks along with
their main vision and timeline of key developments. We then highlight the need
for split federated learning towards the upcoming 6G networks in every aspect,
including 6G technologies (e.g., intelligent physical layer, intelligent edge
computing, zero-touch network management, intelligent resource management) and
6G use cases (e.g., smart grid 2.0, Industry 5.0, connected and autonomous
systems). Furthermore, we review existing datasets along with frameworks that
can help in implementing SFL for 6G networks. We finally identify key technical
challenges, open issues, and future research directions related to SFL-enabled
6G networks
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