5,376 research outputs found
Full-Duplex Non-Orthogonal Multiple Access for Modern Wireless Networks
Non-orthogonal multiple access (NOMA) is an interesting concept to provide
higher capacity for future wireless communications. In this article, we
consider the feasibility and benefits of combining full-duplex operation with
NOMA for modern communication systems. Specifically, we provide a comprehensive
overview on application of full-duplex NOMA in cellular networks, cooperative
and cognitive radio networks, and characterize gains possible due to
full-duplex operation. Accordingly, we discuss challenges, particularly the
self-interference and inter-user interference and provide potential solutions
to interference mitigation and quality-of-service provision based on
beamforming, power control, and link scheduling. We further discuss future
research challenges and interesting directions to pursue to bring full-duplex
NOMA into maturity and use in practice.Comment: Revised, IEEE Wireless Communication Magazin
Effective Capacity in Wireless Networks: A Comprehensive Survey
Low latency applications, such as multimedia communications, autonomous
vehicles, and Tactile Internet are the emerging applications for
next-generation wireless networks, such as 5th generation (5G) mobile networks.
Existing physical-layer channel models, however, do not explicitly consider
quality-of-service (QoS) aware related parameters under specific delay
constraints. To investigate the performance of low-latency applications in
future networks, a new mathematical framework is needed. Effective capacity
(EC), which is a link-layer channel model with QoS-awareness, can be used to
investigate the performance of wireless networks under certain statistical
delay constraints. In this paper, we provide a comprehensive survey on existing
works, that use the EC model in various wireless networks. We summarize the
work related to EC for different networks such as cognitive radio networks
(CRNs), cellular networks, relay networks, adhoc networks, and mesh networks.
We explore five case studies encompassing EC operation with different design
and architectural requirements. We survey various delay-sensitive applications
such as voice and video with their EC analysis under certain delay constraints.
We finally present the future research directions with open issues covering EC
maximization
Resource Allocation in Full-Duplex Communications for Future Wireless Networks
The recent significant progress in realizing full-duplex~(FD) systems has
opened up a promising avenue for improving quality of service (QoS) and quality
of experience (QoE) in future wireless networks. There is an urgent need to
address the diverse set of challenges regarding different aspects of FD network
design, theory, and development. In addition to the self-interference
cancelation signal processing algorithms, network protocols such as resource
management are also essential in the practical design and implementation of FD
wireless networks. This article aims to present the latest development and
future directions of resource allocation in different full duplex systems by
exploring the network resources in different domains, including power, space,
frequency, and device dimensions. Four representative application scenarios are
considered: FD MIMO networks, FD cooperative networks, FD OFDMA cellular
networks, and FD heterogeneous networks. Resource management problems and novel
algorithms in these systems are presented, and key open research directions are
discussed.Comment: 20 pages, 7 figures, accepated in IEEE Wireless Communications, 201
Full-Duplex Relay Selection in Cognitive Underlay Networks
In this work, we analyze the performance of full-duplex relay selection
(FDRS) in spectrum-sharing networks. Contrary to half-duplex relaying,
full-duplex relaying (FDR) enables simultaneous listening/forwarding at the
secondary relay(s), thereby allowing for a higher spectral efficiency. However,
since the source and relay simultaneously transmit in FDR, their superimposed
signal at the primary receiver should now satisfy the existing interference
constraint, which can considerably limit the secondary network throughput. In
this regard, relay selection can offer an adequate solution to boost the
secondary throughput while satisfying the imposed interference limit. We first
analyze the performance of opportunistic FDRS with residual self-interference
(RSI) by deriving the exact cumulative distribution function of its end-to-end
signal-to-interference-plus-noise ratio under Nakagami-m fading. We also
evaluate the offered diversity gain of relay selection for different
full-duplex cooperation schemes in the presence/absence of a direct
source-destination link. When the adopted RSI link gain model is sublinear in
the relay power, which agrees with recent research findings, we show that
remarkable diversity gain can be recovered even in the presence of an
interfering direct link. Second, we evaluate the end-to-end performance of FDRS
with interference constraints due to the presence of a primary receiver.
Finally, the presented exact theoretical findings are verified by numerical
simulations
Harvest the potential of massive MIMO with multi-layer techniques
Massive MIMO is envisioned as a promising technology for 5G wireless networks
due to its high potential to improve both spectral and energy efficiency.
Although the massive MIMO system is based on innovations in the physical layer,
the upper layer techniques also play important roles in harvesting the
performance gains of massive MIMO. In this article, we begin with an analysis
of the benefits and challenges of massive MIMO systems. We then investigate the
multi-layer techniques for incorporating massive MIMO in several important
network deployment scenarios. We conclude this article with a discussion of
open and potential problems for future research.Comment: IEEE Networ
Cooperation in 5G HetNets: Advanced Spectrum Access and D2D Assisted Communications
The evolution of conventional wireless communication networks to the fifth
generation (5G) is driven by an explosive increase in the number of wireless
mobile devices and services, as well as their demand for all-time and
everywhere connectivity, high data rates, low latency, high energy-efficiency
and improved quality of service. To address these challenges, 5G relies on key
technologies, such as full duplex (FD), device-to-device (D2D) communications,
and network densification. In this article, a heterogeneous networking
architecture is envisioned, where cells of different sizes and radio access
technologies coexist. Specifically, collaboration for spectrum access is
explored for both FD- and cognitive-based approaches, and cooperation among
devices is discussed in the context of the state-of-the-art D2D assisted
communication paradigm. The presented cooperative framework is expected to
advance the understandings of the critical technical issues towards dynamic
spectrum management for 5G heterogeneous networks.Comment: to appear in IEEE Wireless Communication
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
Power Control and Relay Selection in Full-Duplex Cognitive Relay Networks: Coherent versus Non-coherent Scenarios
This paper investigates power control and relay selection in Full Duplex
Cognitive Relay Networks (FDCRNs), where the secondary-user (SU) relays can
simultaneously receive and forward the signal from the SU source. We study both
non-coherent and coherent scenarios. In the non-coherent case, the SU relay
forwards the signal from the SU source without regulating the phase, while in
the coherent scenario, the SU relay regulates the phase when forwarding the
signal to minimize the interference at the primary-user (PU) receiver. We
consider the problem of maximizing the transmission rate from the SU source to
the SU destination subject to the interference constraint at the PU receiver
and power constraints at both the SU source and SU relay. We develop
low-complexity and high-performance joint power control and relay selection
algorithms. The superior performance of the proposed algorithms are confirmed
using extensive numerical evaluation. In particular, we demonstrate the
significant gain of phase regulation at the SU relay (i.e., the gain of the
coherent mechanism over the noncoherent mechanism).Comment: The 51st Annual Conference on Information Systems and Sciences 2017
(IEEE CISS 2017
A Survey on 5G: The Next Generation of Mobile Communication
The rapidly increasing number of mobile devices, voluminous data, and higher
data rate are pushing to rethink the current generation of the cellular mobile
communication. The next or fifth generation (5G) cellular networks are expected
to meet high-end requirements. The 5G networks are broadly characterized by
three unique features: ubiquitous connectivity, extremely low latency, and very
high-speed data transfer. The 5G networks would provide novel architectures and
technologies beyond state-of-the-art architectures and technologies. In this
paper, our intent is to find an answer to the question: "what will be done by
5G and how?" We investigate and discuss serious limitations of the fourth
generation (4G) cellular networks and corresponding new features of 5G
networks. We identify challenges in 5G networks, new technologies for 5G
networks, and present a comparative study of the proposed architectures that
can be categorized on the basis of energy-efficiency, network hierarchy, and
network types. Interestingly, the implementation issues, e.g., interference,
QoS, handoff, security-privacy, channel access, and load balancing, hugely
effect the realization of 5G networks. Furthermore, our illustrations highlight
the feasibility of these models through an evaluation of existing
real-experiments and testbeds.Comment: Accepted in Elsevier Physical Communication, 24 pages, 5 figures, 2
table
Power Allocation for Full-Duplex Relay Selection in Underlay Cognitive Radio Networks: Coherent versus Non-Coherent Scenarios
This paper investigates power control and relay selection in Full Duplex
Cognitive Relay Networks (FDCRNs), where the secondary-user (SU) relays can
simultaneously receive data from the SU source and forward them to the SU
destination. We study both non-coherent and coherent scenarios. In the
non-coherent case, the SU relay forwards the signal from the SU source without
regulating the phase; while in the coherent scenario, the SU relay regulates
the phase when forwarding the signal to minimize the interference at the
primary-user (PU) receiver. We consider the problem of maximizing the
transmission rate from the SU source to the SU destination subject to the
interference constraint at the PU receiver and power constraints at both the SU
source and SU relay. We then develop a mathematical model to analyze the data
rate performance of the FDCRN considering the self-interference effects at the
FD relay. We develop low-complexity and high-performance joint power control
and relay selection algorithms. Extensive numerical results are presented to
illustrate the impacts of power level parameters and the self-interference
cancellation quality on the rate performance. Moreover, we demonstrate the
significant gain of phase regulation at the SU relay.Comment: Submitted to TS
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