7,152 research outputs found
Energy-Delay Tradeoffs of Virtual Base Stations With a Computational-Resource-Aware Energy Consumption Model
The next generation (5G) cellular network faces the challenges of efficiency,
flexibility, and sustainability to support data traffic in the mobile Internet
era. To tackle these challenges, cloud-based cellular architectures have been
proposed where virtual base stations (VBSs) play a key role. VBSs bring further
energy savings but also demands a new energy consumption model as well as the
optimization of computational resources. This paper studies the energy-delay
tradeoffs of VBSs with delay tolerant traffic. We propose a
computational-resource-aware energy consumption model to capture the total
energy consumption of a VBS and reflect the dynamic allocation of computational
resources including the number of CPU cores and the CPU speed. Based on the
model, we analyze the energy-delay tradeoffs of a VBS considering BS sleeping
and state switching cost to minimize the weighted sum of power consumption and
average delay. We derive the explicit form of the optimal data transmission
rate and find the condition under which the energy optimal rate exists and is
unique. Opportunities to reduce the average delay and achieve energy savings
simultaneously are observed. We further propose an efficient algorithm to
jointly optimize the data rate and the number of CPU cores. Numerical results
validate our theoretical analyses and under a typical simulation setting we
find more than 60% energy savings can be achieved by VBSs compared with
conventional base stations under the EARTH model, which demonstrates the great
potential of VBSs in 5G cellular systems.Comment: 5 pages, 3 figures, accepted by ICCS'1
Time-dependent generator coordinate method study of mass-asymmetric fission of actinides
Low-energy positive and negative parity collective states in the equilibrium
minimum, and the dynamics of induced fission of actinide nuclei are
investigated in a unified theoretical framework based on the generator
coordinate method (GCM) with the Gaussian overlap approximation (GOA). The
collective potential and inertia tensor, both at zero and finite temperature,
are computed using the self-consistent multidimensionally constrained
relativistic mean field (MDC-RMF) model, based on the energy density functional
DD-PC1. Pairing correlations are treated in the BCS approximation with a
separable pairing force of finite range. A collective quadrupole-octupole
Hamiltonian characterized by zero-temperature axially-symmetric deformation
energy surface and perturbative cranking inertia tensor, is used to model the
low-lying excitation spectrum. The fission fragment charge distributions are
obtained by propagating the initial collective states in time with the
time-dependent GCM+GOA that uses the same quadrupole-octupole Hamiltonian, but
with the collective potential and inertia tensor computed at finite
temperature. The illustrative charge yields of Th, U,
Pu, Cm, and Cf are in very good agreement with
experiment, and the predicted mass asymmetry is consistent with the result of a
recent microscopic study that has attributed the distribution (peak) of the
heavier-fragment nuclei to shell-stabilized octupole deformations.Comment: 10 pages, 8 figures. arXiv admin note: text overlap with
arXiv:1809.0614
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