185 research outputs found
Test su fascio di prototipi del rivelatore a pixel per l'esperimento ATLAS
Silicon pixel detectors, developed to meet LHC requirements, were tested within the ATLAS collaboration in the H8 beam at CERN. Different sensor designs were studied using various versions of front end electronics developed during the R&D process. In this thesis a detailed experimental study of the overall performance of both irradiated and unirradiated detectors is presented, with special enphasis on efficiency, charge collection and spatial resolution. For the first time their dependence on timewalk is carefully investigated. Possible solutions to avoid spatial resolution deterioration due to timewalk are presented and discussed
On the Transport Capability of LAN Cables in All-Analog MIMO-RoC Fronthaul
Centralized Radio Access Network (C-RAN) architecture is the only viable
solution to handle the complex interference scenario generated by massive
antennas and small cells deployment as required by next generation (5G) mobile
networks. In conventional C-RAN, the fronthaul links used to exchange the
signal between Base Band Units (BBUs) and Remote Antenna Units (RAUs) are based
on digital baseband (BB) signals over optical fibers due to the huge bandwidth
required. In this paper we evaluate the transport capability of copper-based
all-analog fronthaul architecture called Radio over Copper (RoC) that leverages
on the pre-existing LAN cables that are already deployed in buildings and
enterprises. In particular, the main contribution of the paper is to evaluate
the number of independent BB signals for multiple antennas system that can be
transported over multi-pair Cat-5/6/7 cables under a predefined fronthauling
transparency condition in terms of maximum BB signal degradation. The MIMO-RoC
proves to be a complementary solution to optical fiber for the last 200m toward
the RAUs, mostly to reuse the existing LAN cables and to power-supply the RAUs
over the same cable
Analog MIMO Radio-over-Copper: Prototype and Preliminary Experimental Results
Analog Multiple-Input Multiple-Output Radio-over-Copper (A-MIMO-RoC) is an
effective all-analog FrontHaul (FH) architecture that exploits any pre-existing
Local Area Network (LAN) cabling infrastructure of buildings to distribute
Radio-Frequency (RF) signals indoors. A-MIMO-RoC, by leveraging a fully analog
implementation, completely avoids any dedicated digital interface by using a
transparent end-to-end system, with consequent latency, bandwidth and cost
benefits. Usually, LAN cables are exploited mainly in the low-frequency
spectrum portion, mostly due to the moderate cable attenuation and crosstalk
among twisted-pairs. Unlike current systems based on LAN cables, the key
feature of the proposed platform is to exploit more efficiently the huge
bandwidth capability offered by LAN cables, that contain 4 twisted-pairs
reaching up to 500 MHz bandwidth/pair when the length is below 100 m. Several
works proposed numerical simulations that assert the feasibility of employing
LAN cables for indoor FH applications up to several hundreds of MHz, but an
A-MIMO-RoC experimental evaluation is still missing. Here, we present some
preliminary results obtained with an A-MIMO-RoC prototype made by low-cost
all-analog/all-passive devices along the signal path. This setup demonstrates
experimentally the feasibility of the proposed analog relaying of MIMO RF
signals over LAN cables up to 400 MHz, thus enabling an efficient exploitation
of the LAN cables transport capabilities for 5G indoor applications.Comment: Part of this work has been accepted as a conference publication to
ISWCS 201
Ordered Tomlinson-Harashima Precoding in G.fast Downstream
G.fast is an upcoming next generation DSL standard envisioned to use
bandwidth up to 212 MHz. Far-end crosstalk (FEXT) at these frequencies greatly
overcomes direct links. Its cancellation based on non-linear
Tomlinson-Harashima Precoding (THP) proved to show significant advantage over
standard linear precoding. This paper proposes a novel THP structure in which
ordering of successive interference pre-cancellation can be optimized for
downstream with non-cooperating receivers. The optimized scheme is compared to
existing THP structure denoted as equal-rate THP which is widely adopted in
wireless downlink. Structure and performance of both methods differ
significantly favoring the proposed scheme. The ordering that maximizes the
minimum rate (max-min fairness) for each tone of the discrete multi-tone
modulation is the familiar V-BLAST ordering. However, V-BLAST does not lead to
the global maximum when applied independently on each tone. The proposed novel
Dynamic Ordering (DO) strategy takes into account asymmetric channel statistics
to yield the highest minimum aggregated rate.Comment: 7 pages, 11 figures, Accepted at the 2015 IEEE Globecom 2015,
Selected Areas in Communications: Access Networks and Systems, 6-10 December,
201
Ordered Tomlinson-Harashima Precoding in G.fast Downstream
G.fast is an upcoming next generation DSL standard envisioned to use
bandwidth up to 212 MHz. Far-end crosstalk (FEXT) at these frequencies greatly
overcomes direct links. Its cancellation based on non-linear
Tomlinson-Harashima Precoding (THP) proved to show significant advantage over
standard linear precoding. This paper proposes a novel THP structure in which
ordering of successive interference pre-cancellation can be optimized for
downstream with non-cooperating receivers. The optimized scheme is compared to
existing THP structure denoted as equal-rate THP which is widely adopted in
wireless downlink. Structure and performance of both methods differ
significantly favoring the proposed scheme. The ordering that maximizes the
minimum rate (max-min fairness) for each tone of the discrete multi-tone
modulation is the familiar V-BLAST ordering. However, V-BLAST does not lead to
the global maximum when applied independently on each tone. The proposed novel
Dynamic Ordering (DO) strategy takes into account asymmetric channel statistics
to yield the highest minimum aggregated rate
RF-Assisted Free-Space Optics for 5G Vehicle-to-Vehicle Communications
Vehicle-to-Vehicle (V2V) communications are being proposed, tested and
deployed to improve road safety and traffic efficiency. However, the automotive
industry poses strict requirements for safety-critical applications, that call
for reliable, low latency and high data rate communications. In this context,
it is widely agreed that both Radio-Frequency (RF) technologies at mmWaves and
Free-Space Optics (FSO) represent promising solutions, although their
performances are severely degraded by transmitter-receiver misalignment due to
the challenging high-mobility conditions. By combining RF and FSO technologies,
this paper proposes a FSO-based V2V communication system where the pointing
coordinates of laser sources are based on vehicle's information exchanged over
a reliable low-rate RF link. Numerical simulations demonstrate that such
compensation mechanism is mandatory to counteract the unavoidable misalignments
induced by vehicle dynamics, and thus to enable FSO technology for V2V
communications even in high mobility scenarios.Comment: Accepted in IEEE ICC 201
Benign Autoencoders
The success of modern machine learning algorithms depends crucially on
efficient data representation and compression through dimensionality reduction.
This practice seemingly contradicts the conventional intuition suggesting that
data processing always leads to information loss. We prove that this intuition
is wrong. For any non-convex problem, there exists an optimal, benign
auto-encoder (BAE) extracting a lower-dimensional data representation that is
strictly beneficial: Compressing model inputs improves model performance. We
prove that BAE projects data onto a manifold whose dimension is the
compressibility dimension of the learning model. We develop and implement an
efficient algorithm for computing BAE and show that BAE improves model
performance in every dataset we consider. Furthermore, by compressing
"malignant" data dimensions, BAE makes learning more stable and robust.Comment: This paper replaces and subsumes arXiv:2110.0888
Radio-over-modes for C-RAN architecture with smart optical resources assignment
In this paper we consider a centralized radio access network (C-RAN) architecture with a fully analog fronthaul link between remote radio heads (RRHs) and baseband units (BBUs) based on the radio over fiber (RoF) paradigm. Mode division multiplexing (MDM) and frequency division multiplexing (FDM) are employed to provide an additional multiplexing signal dimension to meet the huge bandwidth requirements of next generation (5G) wireless mobile systems. The main contribution of the paper is to prove that a smart resource assignment between the radio antennas and the mode/frequency dimensions allows the communication over the RRH-BBU link at rates that are comparable to those achieved by an ideal fronthauling where BBU and RRH are assumed to be co-located, even without any complex and costly optical equalization technique. Validation is on the radio-link capabilities employing multiple antennas to meet the demand for massive MIMO technology
Proyecto de planta modular para distribución de gas GLP para pequeños barrios
Este proyecto tiene por objetivo la determinación de la inversión necesaria para la realización de una Planta Modular para distribución de gas licuado de petróleo (GLP) o alguno de sus derivados.\nEl objetivo es poder brindar servicio de gas natural de red a un pequeño asentamiento urbano al cual no llegue el servicio habitual de gas de red.\nQueda excluido de la evaluación económica, el desarrollo de la red domiciliaria, la cual quedará a cargo dentro del plan de viviendas asociadas
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