9,225 research outputs found
Energy-efficiency improvements for optical access
This article discusses novel approaches to improve energy efficiency of different optical access technologies, including time division multiplexing passive optical network (TDM-PON), time and wavelength division multiplexing PON (TWDM-PON), point-to-point (PTP) access network, wavelength division multiplexing PON (WDM-PON), and orthogonal frequency division multiple access PON (OFDMA-PON). These approaches include cyclic sleep mode, energy-efficient bit interleaving protocol, power reduction at component level, or frequency band selection. Depending on the target optical access technology, one or a combination of different approaches can be applied
MAC-Oriented Programmable Terahertz PHY via Graphene-based Yagi-Uda Antennas
Graphene is enabling a plethora of applications in a wide range of fields due
to its unique electrical, mechanical, and optical properties. In the realm of
wireless communications, graphene shows great promise for the implementation of
miniaturized and tunable antennas in the terahertz band. These unique
advantages open the door to new reconfigurable antenna structures which, in
turn, enable novel communication protocols at different levels of the stack.
This paper explores both aspects by, first, presenting a terahertz
Yagi-Uda-like antenna concept that achieves reconfiguration both in frequency
and beam direction simultaneously. Then, a programmable antenna controller
design is proposed to expose the reconfigurability to the PHY and MAC layers,
and several examples of its applicability are given. The performance and cost
of the proposed scheme is evaluated through full-wave simulations and
comparative analysis, demonstrating reconfigurability at nanosecond granularity
with overheads below 0.02 mm and 0.2 mW.Comment: Accepted for presentation in IEEE WCNC '1
The Expanded Very Large Array
In almost 30 years of operation, the Very Large Array (VLA) has proved to be
a remarkably flexible and productive radio telescope. However, the basic
capabilities of the VLA have changed little since it was designed. A major
expansion utilizing modern technology is currently underway to improve the
capabilities of the VLA by at least an order of magnitude in both sensitivity
and in frequency coverage. The primary elements of the Expanded Very Large
Array (EVLA) project include new or upgraded receivers for continuous frequency
coverage from 1 to 50 GHz, new local oscillator, intermediate frequency, and
wide bandwidth data transmission systems to carry signals with 16 GHz total
bandwidth from each antenna, and a new digital correlator with the capability
to process this bandwidth with an unprecedented number of frequency channels
for an imaging array. Also included are a new monitor and control system and
new software that will provide telescope ease of use. Scheduled for completion
in 2012, the EVLA will provide the world research community with a flexible,
powerful, general-purpose telescope to address current and future astronomical
issues.Comment: Added journal reference: published in Proceedings of the IEEE,
Special Issue on Advances in Radio Astronomy, August 2009, vol. 97, No. 8,
1448-1462 Six figures, one tabl
Manipulating Transverse Modes of Photons for Quantum Cryptography
Several schemes have been proposed to extend Quantum Key Distribution
protocols aiming at improving their security or at providing new physical
substrates for qubit implementation. We present a toolbox to jointly create,
manipulate and measure qubits stored in polarization and transverse-modes
degrees of freedom of single photons. The toolbox includes local operations on
single qubits, controlled operations between the two qubits and projective
measurements over a wide variety of non-local bases in the four dimensional
space of states. We describe how to implement the toolbox to perform an
extended version of the BB84 protocol for this Hilbert space (ideally
transmitting two key bits per photon). We present the experimental
implementation of the measurement scheme both in the regimes of intense light
beams and with single photons. Thus, we show the feasibility of implementing
the protocol providing an interesting example of a new method for quantum
information processing using the polarization and transverse modes of light as
qubits.Comment: 9 pages, 7 figures, 5 table
BDAQ53, a versatile pixel detector readout and test system for the ATLAS and CMS HL-LHC upgrades
BDAQ53 is a readout system and verification framework for hybrid pixel
detector readout chips of the RD53 family. These chips are designed for the
upgrade of the inner tracking detectors of the ATLAS and CMS experiments.
BDAQ53 is used in applications where versatility and rapid customization are
required, such as in laboratory testing environments, test beam campaigns, and
permanent setups for quality control measurements. It consists of custom and
commercial hardware, a Python-based software framework, and FPGA firmware.
BDAQ53 is developed as open source software with both software and firmware
being hosted in a public repository.Comment: 6 pages, 6 figure
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