274 research outputs found
A Tutorial on Beam Management for 3GPP NR at mmWave Frequencies
The millimeter wave (mmWave) frequencies offer the availability of huge
bandwidths to provide unprecedented data rates to next-generation cellular
mobile terminals. However, mmWave links are highly susceptible to rapid channel
variations and suffer from severe free-space pathloss and atmospheric
absorption. To address these challenges, the base stations and the mobile
terminals will use highly directional antennas to achieve sufficient link
budget in wide area networks. The consequence is the need for precise alignment
of the transmitter and the receiver beams, an operation which may increase the
latency of establishing a link, and has important implications for control
layer procedures, such as initial access, handover and beam tracking. This
tutorial provides an overview of recently proposed measurement techniques for
beam and mobility management in mmWave cellular networks, and gives insights
into the design of accurate, reactive and robust control schemes suitable for a
3GPP NR cellular network. We will illustrate that the best strategy depends on
the specific environment in which the nodes are deployed, and give guidelines
to inform the optimal choice as a function of the system parameters.Comment: 22 pages, 19 figures, 10 tables, published in IEEE Communications
Surveys and Tutorials. Please cite it as M. Giordani, M. Polese, A. Roy, D.
Castor and M. Zorzi, "A Tutorial on Beam Management for 3GPP NR at mmWave
Frequencies," in IEEE Communications Surveys & Tutorials, vol. 21, no. 1, pp.
173-196, First quarter 201
Toward End-to-End, Full-Stack 6G Terahertz Networks
Recent evolutions in semiconductors have brought the terahertz band in the
spotlight as an enabler for terabit-per-second communications in 6G networks.
Most of the research so far, however, has focused on understanding the physics
of terahertz devices, circuitry and propagation, and on studying physical layer
solutions. However, integrating this technology in complex mobile networks
requires a proper design of the full communication stack, to address link- and
system-level challenges related to network setup, management, coordination,
energy efficiency, and end-to-end connectivity. This paper provides an overview
of the issues that need to be overcome to introduce the terahertz spectrum in
mobile networks, from a MAC, network and transport layer perspective, with
considerations on the performance of end-to-end data flows on terahertz
connections.Comment: Published on IEEE Communications Magazine, THz Communications: A
Catalyst for the Wireless Future, 7 pages, 6 figure
End-to-End Simulation of 5G mmWave Networks
Due to its potential for multi-gigabit and low latency wireless links,
millimeter wave (mmWave) technology is expected to play a central role in 5th
generation cellular systems. While there has been considerable progress in
understanding the mmWave physical layer, innovations will be required at all
layers of the protocol stack, in both the access and the core network.
Discrete-event network simulation is essential for end-to-end, cross-layer
research and development. This paper provides a tutorial on a recently
developed full-stack mmWave module integrated into the widely used open-source
ns--3 simulator. The module includes a number of detailed statistical channel
models as well as the ability to incorporate real measurements or ray-tracing
data. The Physical (PHY) and Medium Access Control (MAC) layers are modular and
highly customizable, making it easy to integrate algorithms or compare
Orthogonal Frequency Division Multiplexing (OFDM) numerologies, for example.
The module is interfaced with the core network of the ns--3 Long Term Evolution
(LTE) module for full-stack simulations of end-to-end connectivity, and
advanced architectural features, such as dual-connectivity, are also available.
To facilitate the understanding of the module, and verify its correct
functioning, we provide several examples that show the performance of the
custom mmWave stack as well as custom congestion control algorithms designed
specifically for efficient utilization of the mmWave channel.Comment: 25 pages, 16 figures, submitted to IEEE Communications Surveys and
Tutorials (revised Jan. 2018
ns-3 Implementation of the 3GPP MIMO Channel Model for Frequency Spectrum above 6 GHz
Communications at mmWave frequencies will be a key enabler of the next
generation of cellular networks, due to the multi-Gbps rate that can be
achieved. However, there are still several problems that must be solved before
this technology can be widely adopted, primarily associated with the interplay
between the variability of mmWave links and the complexity of mobile networks.
An end-to-end network simulator represents a great tool to assess the
performance of any proposed solution to meet the stringent 5G requirements.
Given the criticality of channel propagation characteristics at higher
frequencies, we present our implementation of the 3GPP channel model for the
6-100 GHz band for the ns-3 end-to-end 5G mmWave module, and detail its
associated MIMO beamforming architecture
Standalone and Non-Standalone Beam Management for 3GPP NR at mmWaves
The next generation of cellular networks will exploit mmWave frequencies to
dramatically increase the network capacity. The communication at such high
frequencies, however, requires directionality to compensate the increase in
propagation loss. Users and base stations need to align their beams during both
initial access and data transmissions, to ensure the maximum gain is reached.
The accuracy of the beam selection, and the delay in updating the beam pair or
performing initial access, impact the end-to-end performance and the quality of
service. In this paper we will present the beam management procedures that 3GPP
has included in the NR specifications, focusing on the different operations
that can be performed in Standalone (SA) and in Non-Standalone (NSA)
deployments. We will also provide a performance comparison among different
schemes, along with design insights on the most important parameters related to
beam management frameworks.Comment: 7 pages, 5 figures, 1 table. Please cite it as M. Giordani, M.
Polese, A. Roy, D. Castor and M. Zorzi, "Standalone and Non-Standalone Beam
Management for 3GPP NR at mmWaves," in IEEE Communications Magazine, vol. 57,
no. 4, pp. 123-129, April 201
Initial Access Frameworks for 3GPP NR at mmWave Frequencies
The use of millimeter wave (mmWave) frequencies for communication will be one
of the innovations of the next generation of cellular mobile networks (5G). It
will provide unprecedented data rates, but is highly susceptible to rapid
channel variations and suffers from severe isotropic pathloss. Highly
directional antennas at the transmitter and the receiver will be used to
compensate for these shortcomings and achieve sufficient link budget in wide
area networks. However, directionality demands precise alignment of the
transmitter and the receiver beams, an operation which has important
implications for control plane procedures, such as initial access, and may
increase the delay of the data transmission. This paper provides a comparison
of measurement frameworks for initial access in mmWave cellular networks in
terms of detection accuracy, reactiveness and overhead, using parameters
recently standardized by the 3GPP and a channel model based on real-world
measurements. We show that the best strategy depends on the specific
environment in which the nodes are deployed, and provide guidelines to
characterize the optimal choice as a function of the system parameters.Comment: 8 pages, 7 figures, 3 tables, accepted to the IEEE 17th Annual
Mediterranean Ad Hoc Networking Workshop (Med-Hoc-Net). arXiv admin note:
substantial text overlap with arXiv:1804.0190
Fastening the Initial Access in 5G NR Sidelink for 6G V2X Networks
The ever-increasing demand for intelligent, automated, and connected mobility
solutions pushes for the development of an innovative sixth Generation (6G) of
cellular networks. A radical transformation on the physical layer of vehicular
communications is planned, with a paradigm shift towards beam-based millimeter
Waves or sub-Terahertz communications, which require precise beam pointing for
guaranteeing the communication link, especially in high mobility. A key design
aspect is a fast and proactive Initial Access (IA) algorithm to select the
optimal beam to be used. In this work, we investigate alternative IA techniques
to fasten the current fifth-generation (5G) standard, targeting an efficient 6G
design. First, we discuss cooperative position-based schemes that rely on the
position information. Then, motivated by the intuition of a non-uniform
distribution of the communication directions due to road topology constraints,
we design two Probabilistic Codebook (PCB) techniques of prioritized beams. In
the first one, the PCBs are built leveraging past collected traffic
information, while in the second one, we use the Hough Transform over the
digital map to extract dominant road directions. We also show that the
information coming from the angular probability distribution allows designing
non-uniform codebook quantization, reducing the degradation of the performances
compared to uniform one. Numerical simulation on realistic scenarios shows that
PCBs-based beam selection outperforms the 5G standard in terms of the number of
IA trials, with a performance comparable to position-based methods, without
requiring the signaling of sensitive information
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