8,460 research outputs found
A Novel Transmission Scheme for the -user Broadcast Channel with Delayed CSIT
The state-dependent -user memoryless Broadcast Channel~(BC) with state
feedback is investigated. We propose a novel transmission scheme and derive its
corresponding achievable rate region, which, compared to some general schemes
that deal with feedback, has the advantage of being relatively simple and thus
is easy to evaluate. In particular, it is shown that the capacity region of the
symmetric erasure BC with an arbitrary input alphabet size is achievable with
the proposed scheme. For the fading Gaussian BC, we derive a symmetric
achievable rate as a function of the signal-to-noise ratio~(SNR) and a small
set of parameters. Besides achieving the optimal degrees of freedom at high
SNR, the proposed scheme is shown, through numerical results, to outperform
existing schemes from the literature in the finite SNR regime.Comment: 30 pages, 3 figures, submitted to IEEE Transactions on Wireless
Communications (revised version
Preamble design using embedded signalling for OFDM broadcast systems based on reduced-complexity distance detection
The second generation digital terrestrial television broadcasting standard (DVB-T2) adopts the so-called P1 symbol as the preamble for initial synchronization. The P1 symbol also carries a number of basic transmission parameters, including the fast Fourier transform size and the single-input/single-output as well as multiple-input/single-output mode, in order to appropriately configure the receiver for carrying out the subsequent processing. In this contribution, an improved preamble design is proposed, where a pair of training sequences is inserted in the frequency domain and their distance is used for transmission parameter signalling. At the receiver, only a low-complexity correlator is required for the detection of the signalling. Both the coarse carrier frequency offset and the signalling can be simultaneously estimated by detecting the above-mentioned correlation. Compared to the standardised P1 symbol, the proposed preamble design significantly reduces the complexity of the receiver while retaining high robustness in frequency-selective fading channels. Furthermore, we demonstrate that the proposed preamble design achieves a better signalling performance than the standardised P1 symbol, despite reducing the numbers of multiplications and additions by about 40% and 20%, respectively
Observer-based fault-tolerant control for a class of networked control systems with transfer delays
Abstract not availableZehui Mao, Bin Jiang, Peng Sh
Quantum logical gates with four-level SQUIDs coupled to a superconducting resonator
We propose a way for realizing a two-qubit controlled phase gate with
superconducting quantum interference devices (SQUIDs) coupled to a
superconducting resonator. In this proposal, the two lowest levels of each
SQUID serve as the logical states and two intermediate levels of each SQUID are
used for the gate realization. We show that neither adjustment of SQUID level
spacings during the gate operation nor uniformity in SQUID parameters is
required by this proposal. In addition, this proposal does not require the
adiabatic passage or a second-order detuning and thus the gate is much faster.Comment: 6 pages, 3 figure
Analysis and Design of Intelligent Logistics System Based on Internet of Things
Based on Internet of things, .NET software development technology and GIS technology, this paper analyzes and designs a system of intelligent distribution information with software engineering life cycle theory as the guide to solve the problem of high complexity and low efficiency of manual operation in logistics and distribution, improve the level of intelligent operation and then improve the operating efficiency. It analyzes the business requirements of the system, then designs its physical architecture, software architecture and system structure, and constructs the terminal node distribution dynamic model of transmission route, realizing the main function modules of the system and verifying the correctness and effectiveness of the system results through systematic and comprehensive tests.
DOI: 10.17762/ijritcc2321-8169.15065
Quantum interface between frequency-uncorrelated down-converted entanglement and atomic-ensemble quantum memory
Photonic entanglement source and quantum memory are two basic building blocks
of linear-optical quantum computation and long-distance quantum communication.
In the past decades, intensive researches have been carried out, and remarkable
progress, particularly based on the spontaneous parametric down-converted
(SPDC) entanglement source and atomic ensembles, has been achieved. Currently,
an important task towards scalable quantum information processing (QIP) is to
efficiently write and read entanglement generated from a SPDC source into and
out of an atomic quantum memory. Here we report the first experimental
realization of a quantum interface by building a 5 MHz frequency-uncorrelated
SPDC source and reversibly mapping the generated entangled photons into and out
of a remote optically thick cold atomic memory using electromagnetically
induced transparency. The frequency correlation between the entangled photons
is almost fully eliminated with a suitable pump pulse. The storage of a
triggered single photon with arbitrary polarization is shown to reach an
average fidelity of 92% for 200 ns storage time. Moreover,
polarization-entangled photon pairs are prepared, and one of photons is stored
in the atomic memory while the other keeps flying. The CHSH Bell's inequality
is measured and violation is clearly observed for storage time up to 1
microsecond. This demonstrates the entanglement is stored and survives during
the storage. Our work establishes a crucial element to implement scalable
all-optical QIP, and thus presents a substantial progress in quantum
information science.Comment: 28 pages, 4 figures, 1 tabl
Magnetar Flare-Driven Bumpy Declining Light Curves in Hydrogen-poor Superluminous Supernovae
Recent observations indicate that hydrogen-poor superluminous supernovae
often display bumpy declining light curves. However, the cause of these
undulations remains unclear. In this paper, we have improved the magnetar
model, which includes flare activities. We present a systematic analysis of a
well-observed SLSNe-I sample with bumpy light curves in the late-phase. These
SLSNe-I were identified from multiple transient surveys, such as the
Pan-STARRS1 Medium Deep Survey (PS1 MDS) and the Zwicky Transient Facility
(ZTF). Our study provides a set of magnetar-powered model light curve fits for
five SLSNe-I, which accurately reproduce observed light curves using reasonable
physical parameters. By extracting essential characteristics of both explosions
and central engines, these fits provide valuable insights into investigating
their potential association with gamma ray burst engines. We found that the
SLSN flares tend to be the dim and long extension of the GRB flares in the peak
luminosity versus peak time plane. Conducting large-scale, high cadence surveys
in the near future could enhance our comprehension of both SLSN undulation
properties and their potential relationship with GRBs by modeling their light
curve characteristics.Comment: 10 pages, 5 figures. Accepted for publication in the Astrophysical
Journa
- …