585 research outputs found
60 GHz MAC Standardization: Progress and Way Forward
Communication at mmWave frequencies has been the focus in the recent years.
In this paper, we discuss standardization efforts in 60 GHz short range
communication and the progress therein. We compare the available standards in
terms of network architecture, medium access control mechanisms, physical layer
techniques and several other features. Comparative analysis indicates that IEEE
802.11ad is likely to lead the short-range indoor communication at 60 GHz. We
bring to the fore resolved and unresolved issues pertaining to robust WLAN
connectivity at 60 GHz. Further, we discuss the role of mmWave bands in 5G
communication scenarios and highlight the further efforts required in terms of
research and standardization
Direct communication radio Iinterface for new radio multicasting and cooperative positioning
Cotutela: Universidad de defensa UNIVERSITA’ MEDITERRANEA DI REGGIO CALABRIARecently, the popularity of Millimeter Wave (mmWave) wireless networks has increased due to their capability to cope with the escalation of mobile data demands caused by the unprecedented proliferation of smart devices in the fifth-generation (5G). Extremely high frequency or mmWave band is a fundamental pillar in the provision of the expected gigabit data rates. Hence, according to both academic and industrial communities, mmWave technology, e.g., 5G New Radio (NR) and WiGig (60 GHz), is considered as one of the main components of 5G and beyond networks. Particularly, the 3rd Generation Partnership Project (3GPP) provides for the use of licensed mmWave sub-bands for the 5G mmWave cellular networks, whereas IEEE actively explores the unlicensed band at 60 GHz for the next-generation wireless local area networks. In this regard, mmWave has been envisaged as a new technology
layout for real-time heavy-traffic and wearable applications.
This very work is devoted to solving the problem of mmWave band communication system while enhancing its advantages through utilizing the direct communication radio interface for NR multicasting, cooperative positioning, and mission-critical applications. The main contributions presented in this work include: (i) a set of mathematical frameworks and simulation tools to characterize multicast traffic delivery in mmWave directional systems; (ii) sidelink
relaying concept exploitation to deal with the channel condition deterioration of dynamic multicast systems and to ensure mission-critical and ultra-reliable low-latency communications; (iii) cooperative positioning techniques analysis for enhancing cellular positioning accuracy for 5G+ emerging applications that require not only improved communication characteristics but also precise localization.
Our study indicates the need for additional mechanisms/research that can be utilized: (i) to further improve multicasting performance in 5G/6G systems; (ii) to investigate sideline aspects, including, but not limited to, standardization perspective and the next relay selection strategies; and (iii) to design cooperative positioning systems based on Device-to-Device (D2D) technology
A Survey of Beam Management for mmWave and THz Communications Towards 6G
Communication in millimeter wave (mmWave) and even terahertz (THz) frequency
bands is ushering in a new era of wireless communications. Beam management,
namely initial access and beam tracking, has been recognized as an essential
technique to ensure robust mmWave/THz communications, especially for mobile
scenarios. However, narrow beams at higher carrier frequency lead to huge beam
measurement overhead, which has a negative impact on beam acquisition and
tracking. In addition, the beam management process is further complicated by
the fluctuation of mmWave/THz channels, the random movement patterns of users,
and the dynamic changes in the environment. For mmWave and THz communications
toward 6G, we have witnessed a substantial increase in research and industrial
attention on artificial intelligence (AI), reconfigurable intelligent surface
(RIS), and integrated sensing and communications (ISAC). The introduction of
these enabling technologies presents both open opportunities and unique
challenges for beam management. In this paper, we present a comprehensive
survey on mmWave and THz beam management. Further, we give some insights on
technical challenges and future research directions in this promising area.Comment: accepted by IEEE Communications Surveys & Tutorial
Massive MIMO is a Reality -- What is Next? Five Promising Research Directions for Antenna Arrays
Massive MIMO (multiple-input multiple-output) is no longer a "wild" or
"promising" concept for future cellular networks - in 2018 it became a reality.
Base stations (BSs) with 64 fully digital transceiver chains were commercially
deployed in several countries, the key ingredients of Massive MIMO have made it
into the 5G standard, the signal processing methods required to achieve
unprecedented spectral efficiency have been developed, and the limitation due
to pilot contamination has been resolved. Even the development of fully digital
Massive MIMO arrays for mmWave frequencies - once viewed prohibitively
complicated and costly - is well underway. In a few years, Massive MIMO with
fully digital transceivers will be a mainstream feature at both sub-6 GHz and
mmWave frequencies. In this paper, we explain how the first chapter of the
Massive MIMO research saga has come to an end, while the story has just begun.
The coming wide-scale deployment of BSs with massive antenna arrays opens the
door to a brand new world where spatial processing capabilities are
omnipresent. In addition to mobile broadband services, the antennas can be used
for other communication applications, such as low-power machine-type or
ultra-reliable communications, as well as non-communication applications such
as radar, sensing and positioning. We outline five new Massive MIMO related
research directions: Extremely large aperture arrays, Holographic Massive MIMO,
Six-dimensional positioning, Large-scale MIMO radar, and Intelligent Massive
MIMO.Comment: 20 pages, 9 figures, submitted to Digital Signal Processin
A Holistic Investigation on Terahertz Propagation and Channel Modeling Toward Vertical Heterogeneous Networks
User-centric and low latency communications can be enabled not only by small
cells but also through ubiquitous connectivity. Recently, the vertical
heterogeneous network (V-HetNet) architecture is proposed to backhaul/fronthaul
a large number of small cells. Like an orchestra, the V-HetNet is a polyphony
of different communication ensembles, including geostationary orbit (GEO), and
low-earth orbit (LEO) satellites (e.g., CubeSats), and networked flying
platforms (NFPs) along with terrestrial communication links. In this study, we
propose the Terahertz (THz) communications to enable the elements of V-HetNets
to function in harmony. As THz links offer a large bandwidth, leading to
ultra-high data rates, it is suitable for backhauling and fronthauling small
cells. Furthermore, THz communications can support numerous applications from
inter-satellite links to in-vivo nanonetworks. However, to savor this harmony,
we need accurate channel models. In this paper, the insights obtained through
our measurement campaigns are highlighted, to reveal the true potential of THz
communications in V-HetNets.Comment: It has been accepted for the publication in IEEE Communications
Magazin
Statistical Approaches for Initial Access in mmWave 5G Systems
mmWave communication systems overcome high attenuation by using multiple
antennas at both the transmitter and the receiver to perform beamforming. Upon
entrance of a user equipment (UE) into a cell a scanning procedure must be
performed by the base station in order to find the UE, in what is known as
initial access (IA) procedure. In this paper we start from the observation that
UEs are more likely to enter from some directions than from others, as they
typically move along streets, while other movements are impossible due to the
presence of obstacles. Moreover, users are entering with a given time
statistics, for example described by inter-arrival times. In this context we
propose scanning strategies for IA that take into account the entrance
statistics. In particular, we propose two approaches: a memory-less random
illumination (MLRI) algorithm and a statistic and memory-based illumination
(SMBI) algorithm. The MLRI algorithm scans a random sector in each slot, based
on the statistics of sector entrance, without memory. The SMBI algorithm
instead scans sectors in a deterministic sequence selected according to the
statistics of sector entrance and time of entrance, and taking into account the
fact that the user has not yet been discovered (thus including memory). We
assess the performance of the proposed methods in terms of average discovery
time
Position Locationing for Millimeter Wave Systems
The vast amount of spectrum available for millimeter wave (mmWave) wireless
communication systems will support accurate real-time positioning concurrent
with communication signaling. This paper demonstrates that accurate estimates
of the position of an unknown node can be determined using estimates of time of
arrival (ToA), angle of arrival (AoA), as well as data fusion or machine
learning. Real-world data at 28 GHz and 73 GHz is used to show that AoA-based
localization techniques will need to be augmented with other positioning
techniques. The fusion of AoA-based positioning with received power
measurements for RXs in an office which has dimensions of 35 m by 65.5 m is
shown to provide location accuracies ranging from 16 cm to 3.25 m, indicating
promise for accurate positioning capabilities in future networks. Received
signal strength intensity (RSSI) based positioning techniques that exploit the
ordering of the received power can be used to determine rough estimates of user
position. Prediction of received signal characteristics is done using 2-D ray
tracing.Comment: GLOBECOM 2018 - 2018 IEEE Global Communications Conference, 6 page
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