82 research outputs found
Enhancing AmBC Systems with Deep Learning for Joint Channel Estimation and Signal Detection
The era of ubiquitous, affordable wireless connectivity has opened doors to
countless practical applications. In this context, ambient backscatter
communication (AmBC) stands out, utilizing passive tags to establish
connections with readers by harnessing reflected ambient radio frequency (RF)
signals. However, conventional data detectors face limitations due to their
inadequate knowledge of channel and RF-source parameters. To address this
challenge, we propose an innovative approach using a deep neural network (DNN)
for channel state estimation (CSI) and signal detection within AmBC systems.
Unlike traditional methods that separate CSI estimation and data detection, our
approach leverages a DNN to implicitly estimate CSI and simultaneously detect
data. The DNN model, trained offline using simulated data derived from channel
statistics, excels in online data recovery, ensuring robust performance in
practical scenarios. Comprehensive evaluations validate the superiority of our
proposed DNN method over traditional detectors, particularly in terms of bit
error rate (BER). In high signal-to-noise ratio (SNR) conditions, our method
exhibits an impressive approximately 20% improvement in BER performance
compared to the maximum likelihood (ML) approach. These results underscore the
effectiveness of our developed approach for AmBC channel estimation and signal
detection. In summary, our method outperforms traditional detectors, bolstering
the reliability and efficiency of AmBC systems, even in challenging channel
conditions.Comment: Accepted for publication in the IEEE Transactions on Communication
Kinetics of exciton photoluminescence in type-II semiconductor superlattices
The exciton decay rate at a rough interface in type-II semiconductor
superlattices is investigated. It is shown that the possibility of
recombination of indirect excitons at a plane interface essentially affects
kinetics of the exciton photoluminescence at a rough interface. This happens
because of strong correlation between the exciton recombination at the plane
interface and at the roughness. Expressions that relate the parameters of the
luminescence kinetics with statistical characteristics of the rough interface
are obtained. The mean height and length of roughnesses in GaAs/AlAs
superlattices are estimated from the experimental data.Comment: 3 PostScript figure
Influence of high-index GaAs substrates on the 2D electron density of
In this paper, we report the theoretical predictions of a high-index GaAs
substrate ((111)A and (311)A) on the subband structure and thereafter on the
2D electron density of Si δ-doped
Al0.33Ga0.67As/In0.15Ga0.85As/GaAs pseudomorphic high
electron mobility transistor (pHEMT) with an additional
InxGa1-xAs
(x > 0.15) thin layer embedded in the channel. We have seen that the
electronic structures and the electron density are quite sensitive to the
additional InxGa1-xAs
(x > 0.15) layer thickness, indium
composition and to their position in the channel. An optimal position of the
additional InxGa1-xAs
layer was found to be corresponding to the
maximum of the first eigen envelope function for the different growth
directions. We report that the optimised electron density is obtained in the
structure grown on (111)A GaAs substrate. In this case the electron transfer
is significantly higher than those grown on (311)A and (001) GaAs substrates
respectively
Non-covalent biofunctionalization of single-walled carbon nanotubes via biotin attachment by π-stacking interactions and pyrrole polymerization
International audienc
Electrochemical Characterization of Biotin Functionalized and Regular Single-Walled Carbon Nanotube Coatings. Application to Amperometric Glucose Biosensors
International audienc
Amperometric Biosensors Based on Biotinylated Single-Walled Carbon Nanotubes
International audienc
Correlation between hysteresis phenomena and hole-like trap in capacitance-voltage characteristics of AlGaN/GaN of Schottky barrier diode
In this work we report on the characteristics of (Ni/Au)/AlGaN/GaN/SiC Schottky barrier diode (SBD). A variety of electrical techniques such as capacitance-voltage (C-V) and deep-level transient spectroscopy (DLTS) measurements were used to characterize the diodes. We observed an hysteresis phenomenon on the C-V characteristics in the Schottky diode. The parasitic effect can be attributed to the presence of traps in the heterostructure. Deep defects analysis was performed by deep-level transient spectroscopy (DLTS). One hole trap have been detected with an activation energy and a capture cross-section of 0.75 eV and 1.093 × 10−11 cm2. The localization and the identification of this trap have occurred and a correlation between the defect and the hysteresis phenomenon has been discussed. At high temperatures, the DLTS signal sometimes becomes negative, likely due to an artificial surface-state effect
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