72 research outputs found
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
enhancing indoor coverage by multi pairs copper cables the analog mimo radio over copper architecture
Nowadays, the majority of indoor coverage issues arise from networks that are mainly designed for outdoor scenarios. Outdoor networks, somewhat uncontrollably, may penetrate indoors with the consequence of coverage holes and outage issues, hence reducing network performances. Moreover, the ever-growing number of devices expected for 5G worsens this situation, calling for novel bandwidth-efficient, low-latency and cost-effective solutions for indoor wireless coverage. This is the focus of this article, which summarizes the content of my Ph.D. thesis by presenting an analog Centralized Radio Access Network (C-RAN) architecture augmented by copper-cable, possibly pre-existing, to provide dense coverage inside buildings. This fronthaul architecture, referred to as Analog MIMO Radio-over-Copper (AMIMO-RoC), is an extreme RAN functional-split-option: the all-analog Remote Radio Units take the form of tiny, simple and cheap in-home devices, and Base Band Unit includes also signals' digitization. The A-MIMO-RoC architecture is introduced in this article starting from demonstrating its theoretical feasibility. Then, the origin and evolution of A-MIMO-RoC are described step-by-step by briefly going through previous works based on numerical analysis and simulations results. Finally, the overall discussion is complemented by results obtained with a prototype platform, which experimentally prove the capability of A-MIMO-RoC to extend indoor coverage over the last 100–200 m. Prototype results thus confirm that the proposed A-MIMO-RoC architecture is a valid solution towards the design of dedicated 5G indoor wireless systems for the billions of buildings which nowadays still suffer from severe indoor coverage issues
Atomic Norm decomposition for sparse model reconstruction applied to positioning and wireless communications
This thesis explores the recovery of sparse signals, arising in the wireless communication and radar system fields, via atomic norm decomposition. Particularly, we
focus on compressed sensing gridless methodologies, which avoid the always existing
error due to the discretization of a continuous space in on-grid methods. We define
the sparse signal by means of a linear combination of so called atoms defined in a
continuous parametrical atom set with infinite cardinality. Those atoms are fully
characterized by a multi-dimensional parameter containing very relevant information
about the application scenario itself. Also, the number of composite atoms is
much lower than the dimension of the problem, which yields sparsity. We address
a gridless optimization solution enforcing sparsity via atomic norm minimization to
extract the parameters that characterize the atom from an observed measurement
of the model, which enables model recovery. We also study a machine learning approach to estimate the number of composite atoms that construct the model, given
that in certain scenarios this number is unknown.
The applications studied in the thesis lay on the field of wireless communications,
particularly on MIMO mmWave channels, which due to their natural properties can
be modeled as sparse. We apply the proposed methods to positioning in automotive
pulse radar working in the mmWave range, where we extract relevant information
such as angle of arrival (AoA), distance and velocity from the received echoes of
objects or targets. Next we study the design of a hybrid precoder for mmWave
channels which allows the reduction of hardware cost in the system by minimizing
as much as possible the number of required RF chains. Last, we explore full channel
estimation by finding the angular parameters that model the channel. For all
the applications we provide a numerical analysis where we compare our proposed
method with state-of-the-art techniques, showing that our proposal outperforms the
alternative methods.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Juan José Murillo Fuentes.- Secretario: Pablo MartÃnez Olmos.- Vocal: David Luengo GarcÃ
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