106 research outputs found
Spectral Efficiency of MIMO Millimeter-Wave Links with Single-Carrier Modulation for 5G Networks
Future wireless networks will extensively rely upon bandwidths centered on
carrier frequencies larger than 10GHz. Indeed, recent research has shown that,
despite the large path-loss, millimeter wave (mmWave) frequencies can be
successfully exploited to transmit very large data-rates over short distances
to slowly moving users. Due to hardware complexity and cost constraints,
single-carrier modulation schemes, as opposed to the popular multi-carrier
schemes, are being considered for use at mmWave frequencies. This paper
presents preliminary studies on the achievable spectral efficiency on a
wireless MIMO link operating at mmWave in a typical 5G scenario. Two different
single-carrier modem schemes are considered, i.e. a traditional modulation
scheme with linear equalization at the receiver, and a single-carrier
modulation with cyclic prefix, frequency-domain equalization and FFT-based
processing at the receiver. Our results show that the former achieves a larger
spectral efficiency than the latter. Results also confirm that the spectral
efficiency increases with the dimension of the antenna array, as well as that
performance gets severely degraded when the link length exceeds 100 meters and
the transmit power falls below 0dBW. Nonetheless, mmWave appear to be very
suited for providing very large data-rates over short distances.Comment: 8 pages, 8 figures, to appear in Proc. 20th International ITG
Workshop on Smart Antennas (WSA2016
Single-Carrier Modulation versus OFDM for Millimeter-Wave Wireless MIMO
This paper presents results on the achievable spectral efficiency and on the
energy efficiency for a wireless multiple-input-multiple-output (MIMO) link
operating at millimeter wave frequencies (mmWave) in a typical 5G scenario. Two
different single-carrier modem schemes are considered, i.e., a traditional
modulation scheme with linear equalization at the receiver, and a
single-carrier modulation with cyclic prefix, frequency-domain equalization and
FFT-based processing at the receiver; these two schemes are compared with a
conventional MIMO-OFDM transceiver structure. Our analysis jointly takes into
account the peculiar characteristics of MIMO channels at mmWave frequencies,
the use of hybrid (analog-digital) pre-coding and post-coding beamformers, the
finite cardinality of the modulation structure, and the non-linear behavior of
the transmitter power amplifiers. Our results show that the best performance is
achieved by single-carrier modulation with time-domain equalization, which
exhibits the smallest loss due to the non-linear distortion, and whose
performance can be further improved by using advanced equalization schemes.
Results also confirm that performance gets severely degraded when the link
length exceeds 90-100 meters and the transmit power falls below 0 dBW.Comment: accepted for publication on IEEE Transactions on Communication
Indici macrofitici per la valutazione della qualit? ecologica dei laghi: MacroIMMI e MTIspecies
No abstract availableIndici per la valutazione della qualit? ecologica dei laghi. Indici macrofitici per la valutazione della qualit? ecologica dei laghi: MacroIMMI e MTIspecie
Abel Prieto - Il primo della prima corriera: Traduzione di Francesca Buzzi e Alessandro Gorla in collaborazione con Irina Bajini
La notizia dell’imminente arrivo dei Rolling Stones all’Avana sconvolge la quotidianità degli avventori dello scombinato “Bar del Pueblo”. Un amore appassionato si intreccia con le vicende e i ricordi di gioventù di Mimí la Tragica, in una Cuba contemporanea caratterizzata dall’insorgere di nuove attività commerciali private.
Abel Prieto Jiménez (Pinar del Río 1950) è uno scrittore e politico cubano. Ministro della Cultura dal 1997 al 2013, attualmente dirige la Oficina del Programa Martiano ed è presidente della Sociedad Cultural “José Martí”. In Italia ha pubblicato diversi testi narrativi, tra i quali Il volo del gatto (Tropea editore, 2001)
A Nanocryotron Ripple Counter Integrated with a Superconducting Nanowire Single-Photon Detector for Megapixel Arrays
Decreasing the number of cables that bring heat into the cryocooler is a
critical issue for all cryoelectronic devices. Especially, arrays of
superconducting nanowire single-photon detectors (SNSPDs) could require more
than readout lines. Performing signal processing operations at low
temperatures could be a solution. Nanocryotrons, superconducting nanowire
three-terminal devices, are good candidates for integrating sensing and
electronics on the same technological platform as SNSPDs in photon-counting
applications. In this work, we demonstrated that it is possible to read out,
process, encode, and store the output of SNSPDs using exclusively
superconducting nanowires. In particular, we present the design and development
of a nanocryotron ripple counter that detects input voltage spikes and converts
the number of pulses to an -digit value. The counting base can be tuned from
2 to higher values, enabling higher maximum counts without enlarging the
circuit. As a proof-of-principle, we first experimentally demonstrated the
building block of the counter, an integer- frequency divider with
ranging from 2 to 5. Then, we demonstrated photon-counting operations at
405\,nm and 1550\,nm by coupling an SNSPD with a 2-digit nanocryotron counter
partially integrated on-chip. The 2-digit counter operated in either base 2 or
base 3 with a bit error rate lower than and a maximum count
rate of s. We simulated circuit architectures for
integrated readout of the counter state, and we evaluated the capabilities of
reading out an SNSPD megapixel array that would collect up to counts
per second. The results of this work, combined with our recent publications on
a nanocryotron shift register and logic gates, pave the way for the development
of nanocryotron processors, from which multiple superconducting platforms may
benefit
A Superconducting Nanowire Binary Shift Register
We present a design for a superconducting nanowire binary shift register,
which stores digital states in the form of circulating supercurrents in
high-kinetic-inductance loops. Adjacent superconducting loops are connected
with nanocryotrons, three terminal electrothermal switches, and fed with an
alternating two-phase clock to synchronously transfer the digital state between
the loops. A two-loop serial-input shift register was fabricated with thin-film
NbN and achieved a bit error rate less than , operating at a maximum
clock frequency of and in an out-of-plane magnetic field up
to . A shift register based on this technology offers an
integrated solution for low-power readout of superconducting nanowire single
photon detector arrays, and is capable of interfacing directly with
room-temperature electronics and operating unshielded in high magnetic field
environments.Comment: The following article has been published in Applied Physics Letters
issue 122. 10 pages, 3 figure
A Nanocryotron Memory and Logic Family
The development of superconducting electronics based on nanocryotrons has
been limited so far to few-device circuits, in part due to the lack of standard
and robust logic cells. Here, we introduce and experimentally demonstrate
designs for a set of nanocryotron-based building blocks that can be configured
and combined to implement memory and logic functions. The devices were
fabricated by patterning a single superconducting layer of niobium nitride and
measured in liquid helium on a wide range of operating points. The tests show
bit error rates with above margins up to MHz and the
possibility of operating under the effect of a perpendicular mT magnetic
field, with margins at MHz. Additionally, we designed and
measured an equivalent delay flip-flop made of two memory cells to show the
possibility of combining multiple building blocks to make larger circuits.
These blocks may constitute a solid foundation for the development of
nanocryotron logic circuits and finite-state machines with potential
applications in the integrated processing and control of superconducting
nanowire single-photon detectors.Comment: Submitted for publication in the Applied Physics Letters special
issue "Advances in Superconducting Logic", 8 pages, 5 figure
Improved fed-batch processes with Wickerhamomyces anomalus WC 1501 for the production of D-arabitol from pure glycerol
D-Arabitol, a five-carbon sugar alcohol, represents a main target of microbial biorefineries aiming to valorize cheap substrates. The yeast Wickerhamomyces anomalus WC 1501 is known to produce arabitol in a glycerol-based nitrogen-limited medium and preliminary fed-batch processes with this yeast were reported to yield 18.0 g/L arabitol
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