3,725 research outputs found
A Data-Aided Channel Estimation Scheme for Decoupled Systems in Heterogeneous Networks
Uplink/downlink (UL/DL) decoupling promises more flexible cell association
and higher throughput in heterogeneous networks (HetNets), however, it hampers
the acquisition of DL channel state information (CSI) in time-division-duplex
(TDD) systems due to different base stations (BSs) connected in UL/DL. In this
paper, we propose a novel data-aided (DA) channel estimation scheme to address
this problem by utilizing decoded UL data to exploit CSI from received UL data
signal in decoupled HetNets where a massive multiple-input multiple-output BS
and dense small cell BSs are deployed. We analytically estimate BER performance
of UL decoded data, which are used to derive an approximated normalized mean
square error (NMSE) expression of the DA minimum mean square error (MMSE)
estimator. Compared with the conventional least square (LS) and MMSE, it is
shown that NMSE performances of all estimators are determined by their
signal-to-noise ratio (SNR)-like terms and there is an increment consisting of
UL data power, UL data length and BER values in the SNR-like term of DA method,
which suggests DA method outperforms the conventional ones in any scenarios.
Higher UL data power, longer UL data length and better BER performance lead to
more accurate estimated channels with DA method. Numerical results verify that
the analytical BER and NMSE results are close to the simulated ones and a
remarkable gain in both NMSE and DL rate can be achieved by DA method in
multiple scenarios with different modulations
Single-pixel imaging with origami pattern construction
Single-pixel compressive imaging can recover images from a small amount of
measurements, offering many benefits especially for the scenes where the array
detection is unavailable. However, the widely used random patterns fail to
explore internal relations between the patterns and the image reconstruction.
Here we propose a single-pixel imaging method based on origami pattern
construction with a better imaging quality, but with less uncertainty of the
pattern sequence. It can decrease the sampling ratio even to 0.5\%, really
realizing super sub-Nyquist sampling. The experimental realization of this
approach is a big step forward toward the real-time compressive video
applications.Comment: 12 pages, 6 figure
Research on the Permeability and Earthquake Damage of an Earth Dam Foundation
The experiences on geological investigation, permeability test, prediction of seepage failure patterns and the earthquake damage of an earth dam foundation are presented in this paper. Basing on the monitoring data and seismic records observed from the seismic station on the dam, the prediction of reservoir induced earthquake and possibility of liquefaction are analysed
System Design of Internet-of-Things for Residential Smart Grid
Internet-of-Things (IoTs) envisions to integrate, coordinate, communicate,
and collaborate real-world objects in order to perform daily tasks in a more
intelligent and efficient manner. To comprehend this vision, this paper studies
the design of a large scale IoT system for smart grid application, which
constitutes a large number of home users and has the requirement of fast
response time. In particular, we focus on the messaging protocol of a universal
IoT home gateway, where our cloud enabled system consists of a backend server,
unified home gateway (UHG) at the end users, and user interface for mobile
devices. We discuss the features of such IoT system to support a large scale
deployment with a UHG and real-time residential smart grid applications. Based
on the requirements, we design an IoT system using the XMPP protocol, and
implemented in a testbed for energy management applications. To show the
effectiveness of the designed testbed, we present some results using the
proposed IoT architecture.Comment: 10 pages, 6 figures, journal pape
Gutzwiller Projected wavefunctions in the fermonic theory of S=1 spin chains
We study in this paper a series of Gutzwiller Projected wavefunctions for S=1
spin chains obtained from a fermionic mean-field theory for general S>1/2 spin
systems [Phys. Rev. B 81, 224417] applied to the bilinear-biquadratic (J-K)
model. The free-fermion mean field states before the projection are 1D paring
states. By comparing the energies and correlation functions of the projected
pairing states with those obtained from known results, we show that the
optimized Gutzwiller projected wavefunctions are very good trial ground state
wavefunctions for the antiferromagnetic bilinear-biquadratic model in the
regime K0). We find that different topological phases of the
free-fermion paring states correspond to different spin phases: the weak
pairing (topologically non-trivial) state gives rise to the Haldane phase,
whereas the strong pairing (topologically trivial) state gives rise to the
dimer phase. In particular the mapping between the Haldane phase and Gutwziller
wavefunction is exact at the AKLT point K=1/3. The transition point between the
two phases determined by the optimized Gutzwiller Projected wavefunction is in
good agreement with the known result. The effect of Z2 gauge fluctuations above
the mean field theory is analyzed.Comment: 10 pages,7 figure
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