822 research outputs found
Resource Allocation for Device-to-Device Communications Underlaying Heterogeneous Cellular Networks Using Coalitional Games
Heterogeneous cellular networks (HCNs) with millimeter wave (mmWave)
communications included are emerging as a promising candidate for the fifth
generation mobile network. With highly directional antenna arrays, mmWave links
are able to provide several-Gbps transmission rate. However, mmWave links are
easily blocked without line of sight. On the other hand, D2D communications
have been proposed to support many content based applications, and need to
share resources with users in HCNs to improve spectral reuse and enhance system
capacity. Consequently, an efficient resource allocation scheme for D2D pairs
among both mmWave and the cellular carrier band is needed. In this paper, we
first formulate the problem of the resource allocation among mmWave and the
cellular band for multiple D2D pairs from the view point of game theory. Then,
with the characteristics of cellular and mmWave communications considered, we
propose a coalition formation game to maximize the system sum rate in
statistical average sense. We also theoretically prove that our proposed game
converges to a Nash-stable equilibrium and further reaches the near-optimal
solution with fast convergence rate. Through extensive simulations under
various system parameters, we demonstrate the superior performance of our
scheme in terms of the system sum rate compared with several other practical
schemes.Comment: 13 pages, 12 figure
Time reversal Aharonov-Casher effect in mesoscopic rings with Rashba spin-orbital interaction
The time reversal Aharonov-Casher (AC) interference effect in the mesoscopic
ring structures, based on the experiment in Phys. Rev. Lett. \textbf{97},
196803 (2006), is studied theoretically. The transmission curves are calculated
from the scattering matrix formalism, and the time reversal AC interference
frequency is singled out from the Fourier spectra in numerical simulations.
This frequency is in good agreement with analytical result. It is also shown
that in the absent of magnetic field, the Altshuler-Aronov-Spivak type (time
reversal) AC interference retains under the influence of strong disorder, while
the Aharonov-Bohm type AC interference is suppressed.Comment: 5 pages, 4 figures, accepted by Phys. Rev.
Geography and similarity of regional cuisines in China
Food occupies a central position in every culture and it is therefore of
great interest to understand the evolution of food culture. The advent of the
World Wide Web and online recipe repositories has begun to provide
unprecedented opportunities for data-driven, quantitative study of food
culture. Here we harness an online database documenting recipes from various
Chinese regional cuisines and investigate the similarity of regional cuisines
in terms of geography and climate. We found that the geographical proximity,
rather than climate proximity is a crucial factor that determines the
similarity of regional cuisines. We develop a model of regional cuisine
evolution that provides helpful clues to understand the evolution of cuisines
and cultures.Comment: 13 pages, 11 figures and 2 table
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