881 research outputs found
An Overview of Signal Processing Techniques for Millimeter Wave MIMO Systems
Communication at millimeter wave (mmWave) frequencies is defining a new era
of wireless communication. The mmWave band offers higher bandwidth
communication channels versus those presently used in commercial wireless
systems. The applications of mmWave are immense: wireless local and personal
area networks in the unlicensed band, 5G cellular systems, not to mention
vehicular area networks, ad hoc networks, and wearables. Signal processing is
critical for enabling the next generation of mmWave communication. Due to the
use of large antenna arrays at the transmitter and receiver, combined with
radio frequency and mixed signal power constraints, new multiple-input
multiple-output (MIMO) communication signal processing techniques are needed.
Because of the wide bandwidths, low complexity transceiver algorithms become
important. There are opportunities to exploit techniques like compressed
sensing for channel estimation and beamforming. This article provides an
overview of signal processing challenges in mmWave wireless systems, with an
emphasis on those faced by using MIMO communication at higher carrier
frequencies.Comment: Submitted to IEEE Journal of Selected Topics in Signal Processin
Wireless Terahertz System Architectures for Networks Beyond 5G
The present white paper focuses on the system requirements of TERRANOVA.
Initially details the key use cases for the TERRANOVA technology and presents
the description of the network architecture. In more detail, the use cases are
classified into two categories, namely backhaul & fronthaul and access and
small cell backhaul. The first category refers to fibre extender,
point-to-point and redundancy applications, whereas the latter is designed to
support backup connection for small and medium-sized enterprises (SMEs),
internet of things (IoT) dense environments, data centres, indoor wireless
access, ad hoc networks, and last mile access. Then, it provides the networks
architecture for the TERRANOVA system as well as the network elements that need
to be deployed. The use cases are matched to specific technical scenarios,
namely outdoor fixed point-to-point (P2P), outdoor/indoor individual
point-to-multipoint (P2MP), and outdoor/indoor "quasi"-omnidirection, and the
key performance requirements of each scenario are identified. Likewise, we
present the breakthrough novel technology concepts, including the joint design
of baseband signal processing for the complete optical and wireless link, the
development of broadband and spectrally efficient RF-frontends for frequencies
>275 GHz, as well as channel modelling, waveforms, antenna array and
multiple-access schemes design, which we are going to use in order to satisfy
the presented requirements. Next, an overview of the required new
functionalities in both physical (PHY) layer and medium access control (MAC)
layers in the TERRANOVA system architecture will be given. Finally, the
individual enablers of the TERRANOVA system are combined to develop particular
candidate architectures for each of the three technical scenarios.Comment: 73 pages, 31 figures, 7 tables. arXiv admin note: text overlap with
arXiv:1503.00697 by other author
Millimeter Wave Cellular Wireless Networks: Potentials and Challenges
Millimeter wave (mmW) frequencies between 30 and 300 GHz are a new frontier
for cellular communication that offers the promise of orders of magnitude
greater bandwidths combined with further gains via beamforming and spatial
multiplexing from multi-element antenna arrays. This paper surveys measurements
and capacity studies to assess this technology with a focus on small cell
deployments in urban environments. The conclusions are extremely encouraging;
measurements in New York City at 28 and 73 GHz demonstrate that, even in an
urban canyon environment, significant non-line-of-sight (NLOS) outdoor,
street-level coverage is possible up to approximately 200 m from a potential
low power micro- or picocell base station. In addition, based on statistical
channel models from these measurements, it is shown that mmW systems can offer
more than an order of magnitude increase in capacity over current
state-of-the-art 4G cellular networks at current cell densities. Cellular
systems, however, will need to be significantly redesigned to fully achieve
these gains. Specifically, the requirement of highly directional and adaptive
transmissions, directional isolation between links and significant
possibilities of outage have strong implications on multiple access, channel
structure, synchronization and receiver design. To address these challenges,
the paper discusses how various technologies including adaptive beamforming,
multihop relaying, heterogeneous network architectures and carrier aggregation
can be leveraged in the mmW context.Comment: 17 pages, 15 figures. arXiv admin note: text overlap with
arXiv:1312.492
Millimeter Wave Beamforming for Wireless Backhaul and Access in Small Cell Networks
Recently, there has been considerable interest in new tiered network cellular
architectures, which would likely use many more cell sites than found today.
Two major challenges will be i) providing backhaul to all of these cells and
ii) finding efficient techniques to leverage higher frequency bands for mobile
access and backhaul. This paper proposes the use of outdoor millimeter wave
communications for backhaul networking between cells and mobile access within a
cell. To overcome the outdoor impairments found in millimeter wave propagation,
this paper studies beamforming using large arrays. However, such systems will
require narrow beams, increasing sensitivity to movement caused by pole sway
and other environmental concerns. To overcome this, we propose an efficient
beam alignment technique using adaptive subspace sampling and hierarchical beam
codebooks. A wind sway analysis is presented to establish a notion of beam
coherence time. This highlights a previously unexplored tradeoff between array
size and wind-induced movement. Generally, it is not possible to use larger
arrays without risking a corresponding performance loss from wind-induced beam
misalignment. The performance of the proposed alignment technique is analyzed
and compared with other search and alignment methods. The results show
significant performance improvement with reduced search time.Comment: 34 pages, 15 figures, Submitted to IEEE Transactions on
Communications for possible publicatio
Low-Latency Heterogeneous Networks with Millimeter-Wave Communications
Heterogeneous network (HetNet) is a key enabler to largely boost network
coverage and capacity in the forthcoming fifth-generation (5G) and beyond. To
support the explosively growing mobile data volumes, wireless communications
with millimeter-wave (mm-wave) radios have attracted massive attention, which
is widely considered as a promising candidate in 5G HetNets. In this article,
we give an overview on the end-to-end latency of HetNets with mm-wave
communications. In general, it is rather challenging for formulating and
optimizing the delay problem with buffers in mm-wave communications, since
conventional graph-based network optimization techniques are not applicable
when queues are considered. Toward this end, we develop an adaptive low-latency
strategy, which uses cooperative networking to reduce the end-to-end latency.
Then, we evaluate the performance of the introduced strategy. Results reveal
the importance of proper cooperative networking in reducing the end-to-end
latency. In addition, we have identified several challenges in future research
for low-latency mm-wave HetNets.Comment: to appear in IEEE Communications Magazin
A Survey of Millimeter Wave (mmWave) Communications for 5G: Opportunities and Challenges
With the explosive growth of mobile data demand, the fifth generation (5G)
mobile network would exploit the enormous amount of spectrum in the millimeter
wave (mmWave) bands to greatly increase communication capacity. There are
fundamental differences between mmWave communications and existing other
communication systems, in terms of high propagation loss, directivity, and
sensitivity to blockage. These characteristics of mmWave communications pose
several challenges to fully exploit the potential of mmWave communications,
including integrated circuits and system design, interference management,
spatial reuse, anti-blockage, and dynamics control. To address these
challenges, we carry out a survey of existing solutions and standards, and
propose design guidelines in architectures and protocols for mmWave
communications. We also discuss the potential applications of mmWave
communications in the 5G network, including the small cell access, the cellular
access, and the wireless backhaul. Finally, we discuss relevant open research
issues including the new physical layer technology, software-defined network
architecture, measurements of network state information, efficient control
mechanisms, and heterogeneous networking, which should be further investigated
to facilitate the deployment of mmWave communication systems in the future 5G
networks.Comment: 17 pages, 8 figures, 7 tables, Journal pape
Millimeter-wave Gbps Broadband Evolution towards 5G: Fixed Access and Backhaul
As wireless communication evolves towards 5G, both fixed broadband and mobile
broadband will play a crucial part in providing the Gbps infrastructure for a
connected society. This paper proposes a Millimeter-wave Gbps Broadband (MGB)
system as the solution to two critical problems in this evolution: last-mile
access for fixed broadband and small cell backhaul for mobile broadband. The
key idea is to use spectrum that is already available in the millimeter wave
bands for fixed wireless access with optimized dynamic beamforming and massive
MIMO infrastructure to achieve high capacity with wide area coverage. This
paper explains the MGB concept and describes potential array architectures for
realizing the system. Simulations demonstrate that with 500 MHz of bandwidth
(at 39 GHz band) and 28 dBm transmission power (55 dBm EIRP), it is possible to
provide more than 11 Gbps backhaul capacity for 96 small cells within 1-km
radius.Comment: 6 pages, 4 figures, 2 tables, submitted to IEEE Communications
Magazin
Modeling and Analyzing Millimeter Wave Cellular Systems
We provide a comprehensive overview of mathematical models and analytical
techniques for millimeter wave (mmWave) cellular systems. The two fundamental
physical differences from conventional Sub-6GHz cellular systems are (i)
vulnerability to blocking, and (ii) the need for significant directionality at
the transmitter and/or receiver, which is achieved through the use of large
antenna arrays of small individual elements. We overview and compare models for
both of these factors, and present a baseline analytical approach based on
stochastic geometry that allows the computation of the statistical
distributions of the downlink signal-to-interference-plus-noise ratio (SINR)
and also the per link data rate, which depends on the SINR as well as the
average load. There are many implications of the models and analysis: (a)
mmWave systems are significantly more noise-limited than at Sub-6GHz for most
parameter configurations; (b) initial access is much more difficult in mmWave;
(c) self-backhauling is more viable than in Sub-6GHz systems which makes
ultra-dense deployments more viable, but this leads to increasingly
interference-limited behavior; and (d) in sharp contrast to Sub-6GHz systems
cellular operators can mutually benefit by sharing their spectrum licenses
despite the uncontrolled interference that results from doing so. We conclude
by outlining several important extensions of the baseline model, many of which
are promising avenues for future research.Comment: 50 pages, 10 figures, submitted to IEEE Trans. Communications,
invited pape
Cellular Network Architectures for the Society in Motion
Due to rising mobility worldwide, a growing number of people utilizes
cellular network services while on the move. Persistent urbanization trends
raise the number of daily commuters, leading to a situation where
telecommunication requirements are mainly dictated by two categories of users:
1) Static users inside buildings, demanding instantaneous and virtually
bandwidth unlimited access to the Internet and Cloud services; 2) moving users
outside, expecting ubiquitous and seamless mobility even at high velocity.
While most work on future mobile communications is motivated by the first
category of users, we outline in this article a layered cellular network
architecture that has the potential to efficiently support both user groups
simultaneously. We deduce novel transceiver architectures and derive research
questions that need to be tackled to effectively maintain wireless connectivity
for the envisioned Society in Motion
A Survey on Low Latency Towards 5G: RAN, Core Network and Caching Solutions
The fifth generation (5G) wireless network technology is to be standardized
by 2020, where main goals are to improve capacity, reliability, and energy
efficiency, while reducing latency and massively increasing connection density.
An integral part of 5G is the capability to transmit touch perception type
real-time communication empowered by applicable robotics and haptics equipment
at the network edge. In this regard, we need drastic changes in network
architecture including core and radio access network (RAN) for achieving
end-to-end latency on the order of 1 ms. In this paper, we present a detailed
survey on the emerging technologies to achieve low latency communications
considering three different solution domains: RAN, core network, and caching.
We also present a general overview of 5G cellular networks composed of software
defined network (SDN), network function virtualization (NFV), caching, and
mobile edge computing (MEC) capable of meeting latency and other 5G
requirements.Comment: Accepted in IEEE Communications Surveys and Tutorial
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