2,742 research outputs found
Electromagnetic Lens-focusing Antenna Enabled Massive MIMO: Performance Improvement and Cost Reduction
Massive multiple-input multiple-output (MIMO) techniques have been recently
advanced to tremendously improve the performance of wireless communication
networks. However, the use of very large antenna arrays at the base stations
(BSs) brings new issues, such as the significantly increased hardware and
signal processing costs. In order to reap the enormous gain of massive MIMO and
yet reduce its cost to an affordable level, this paper proposes a novel system
design by integrating an electromagnetic (EM) lens with the large antenna
array, termed the EM-lens enabled MIMO. The EM lens has the capability of
focusing the power of an incident wave to a small area of the antenna array,
while the location of the focal area varies with the angle of arrival (AoA) of
the wave. Therefore, in practical scenarios where the arriving signals from
geographically separated users have different AoAs, the EM-lens enabled system
provides two new benefits, namely energy focusing and spatial interference
rejection. By taking into account the effects of imperfect channel estimation
via pilot-assisted training, in this paper we analytically show that the
average received signal-to-noise ratio (SNR) in both the single-user and
multiuser uplink transmissions can be strictly improved by the EM-lens enabled
system. Furthermore, we demonstrate that the proposed design makes it possible
to considerably reduce the hardware and signal processing costs with only
slight degradations in performance. To this end, two complexity/cost reduction
schemes are proposed, which are small-MIMO processing with parallel receiver
filtering applied over subgroups of antennas to reduce the computational
complexity, and channel covariance based antenna selection to reduce the
required number of radio frequency (RF) chains. Numerical results are provided
to corroborate our analysis.Comment: 30 pages, 9 figure
On the Relation of Exercising of Patent Rights and Antimonopoly Law
Antimonopoly law provides exemption for the legitimate exercising of patent rights, casts regulation and control over the patent abuse. This article expounds the exemption subject, exemption condition, exemption occasion as well as exemption category, elucidates the relation of abuse behavior and antimonopoly law, puts forward concrete regulating approach on the patent abuse by antimonopoly law. Key words: legitimate exercising of patent rights, patent abuse, antimonopoly law Résumé: le juste exercice du droit de propriété industrielle est immunisé selon la loi antitrust, j’expose dans cette thèse l’objet, la condition, l’occasion et la catégorie de son immunité. Pourtant, l’abus du droit de propriété industrielle est restreint aussi selon la loi antitrust, j’explique la relation entre l’abus du droit de propriété industrielle et la loi antitrust, puis propose mon projet afin de restreindre l’abus du droit de propriété industrielle par la loi antitrust. Mots-Clés: le juste exercice du droit de propriété industrielle, l’abus du droit de propriété industrielle, la loi antitrus
N′-Diphenylmethylene-2-hydroxybenzohydrazide
The title compound, C20H16N2O2, was synthesized by the reaction of 2-hydroxybenzohydrazide with diphenylmethanone. The dihedral angle between the phenyl rings is 76.28 (11)°. The amino H atom is involved in an intramolecular N—H⋯O hydrogen bond. In the crystal structure, the hydroxy groups and carbonyl O atoms form intermolecular O—H⋯O hydrogen bonds, which link the molecules into chains running along the b axis
Revisit assignments of the new excited states with QCD sum rules
In this article, we distinguish the contributions of the positive parity and
negative parity states, study the masses and pole residues of the
1S, 1P, 2S and 2P states with the spin and
using the QCD sum rules in a consistent way, and revisit the
assignments of the new narrow excited states. The predictions
support assigning the to be the 1P state with
, assigning the to be the 1P
state with or the 2S state with
, and assigning to be the 2S
state with .Comment: 19 pages, 22 figures. arXiv admin note: text overlap with
arXiv:1705.0774
Coupled-channel analysis of the possible , and molecular states
We perform a coupled-channel study of the possible deuteron-like molecules
with two heavy flavor quarks, including the systems of with
double charm, with double bottom and
with both charm and bottom, within the
one-boson-exchange model. In our study, we take into account the S-D mixing
which plays an important role in the formation of the loosely bound deuteron,
and particularly, the coupled-channel effect in the flavor space. According to
our calculation, the states and
with double charm, the states
,
and
with double bottom, and
the states and
with both charm and bottom are good
molecule candidates. However, the existence of the states
with double charm and
with both charm and bottom is ruled out.Comment: 1 figure added, published in Physical Review
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