45,085 research outputs found
Network Coding Tree Algorithm for Multiple Access System
Network coding is famous for significantly improving the throughput of
networks. The successful decoding of the network coded data relies on some side
information of the original data. In that framework, independent data flows are
usually first decoded and then network coded by relay nodes. If appropriate
signal design is adopted, physical layer network coding is a natural way in
wireless networks. In this work, a network coding tree algorithm which enhances
the efficiency of the multiple access system (MAS) is presented. For MAS,
existing works tried to avoid the collisions while collisions happen frequently
under heavy load. By introducing network coding to MAS, our proposed algorithm
achieves a better performance of throughput and delay. When multiple users
transmit signal in a time slot, the mexed signals are saved and used to jointly
decode the collided frames after some component frames of the network coded
frame are received. Splitting tree structure is extended to the new algorithm
for collision solving. The throughput of the system and average delay of frames
are presented in a recursive way. Besides, extensive simulations show that
network coding tree algorithm enhances the system throughput and decreases the
average frame delay compared with other algorithms. Hence, it improves the
system performance
Difference of Oxide Hetero-Structure Junctions with Semiconductor Electronic Devices
Charge carrier injection performed in Pr0.7Ca0.3MnO3 (PCMO) hetero-structure
junctions exhibits stable without electric fields and dramatic changes in both
resistances and interface barriers, which are entirely different from behaviors
of semiconductor devices. Disappearance and reversion of interface barriers
suggest that the adjustable resistance switching of such hetero-structure oxide
devices should associate with motion of charge carriers across interfaces. The
results suggested that injected carriers should be still staying in devices and
resulted in changes in properties, which guided to a carrier self-trapping and
releasing picture in strongly correlated electronic framework. Observations in
PCMO and oxygen deficient CeO2 devices show that oxides as functional materials
could be used in microelectronics with some novel properties, in which
interface is very important.Comment: 8 pages, 4 figure
Critical correlations in an ultracold Bose gas revealed by means of a temporal Talbot-Lau interferometer
We study experimentally the critical correlation in an ultra-cold Bose gas
with a temporal Talbot-Lau (TL) interferometer. Near the critical temperature,
we observe a bi-modal density distribution in an ultra-cold Bose gas after the
application of the TL interferometer. The measured fraction of the narrower
peak in the density distribution displays a clear peak within the critical
regime. The peak position agrees with the critical temperature calculated with
the finite-size and interaction corrections. The critical exponents are
extracted from the peak and they agree with the critical exponents for the
correlation length.Comment: 5 pages, 3 figures and supplemental materia
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