3,727 research outputs found
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
A Survey on MIMO Transmission with Discrete Input Signals: Technical Challenges, Advances, and Future Trends
Multiple antennas have been exploited for spatial multiplexing and diversity
transmission in a wide range of communication applications. However, most of
the advances in the design of high speed wireless multiple-input multiple
output (MIMO) systems are based on information-theoretic principles that
demonstrate how to efficiently transmit signals conforming to Gaussian
distribution. Although the Gaussian signal is capacity-achieving, signals
conforming to discrete constellations are transmitted in practical
communication systems. As a result, this paper is motivated to provide a
comprehensive overview on MIMO transmission design with discrete input signals.
We first summarize the existing fundamental results for MIMO systems with
discrete input signals. Then, focusing on the basic point-to-point MIMO
systems, we examine transmission schemes based on three most important criteria
for communication systems: the mutual information driven designs, the mean
square error driven designs, and the diversity driven designs. Particularly, a
unified framework which designs low complexity transmission schemes applicable
to massive MIMO systems in upcoming 5G wireless networks is provided in the
first time. Moreover, adaptive transmission designs which switch among these
criteria based on the channel conditions to formulate the best transmission
strategy are discussed. Then, we provide a survey of the transmission designs
with discrete input signals for multiuser MIMO scenarios, including MIMO uplink
transmission, MIMO downlink transmission, MIMO interference channel, and MIMO
wiretap channel. Additionally, we discuss the transmission designs with
discrete input signals for other systems using MIMO technology. Finally,
technical challenges which remain unresolved at the time of writing are
summarized and the future trends of transmission designs with discrete input
signals are addressed.Comment: 110 pages, 512 references, submit to Proceedings of the IEE
Energy-Efficient Power Allocation for Secure Communications in Large-Scale MIMO Relaying Systems
In this paper, we address the problem of energy-efficient power allocation
for secure communications in an amplify-and-forward (AF) large-scale
multiple-input multiple-output (LS-MIMO) relaying system in presence of a
passive eavesdropper. The benefits of an AF LS-MIMO relay are exploited to
significantly improve the secrecy performance, especially the secrecy energy
efficiency (bit per Joule). We first analyze the impact of transmit power at
the relay on the secrecy outage capacity, and prove that the secrecy outage
capacity is a concave function of transmit power under very practical
assumptions, i.e. no eavesdropper channel state information (CSI) and imperfect
legitimate CSI. Then, we propose an energy-efficient power allocation scheme to
maximize the secrecy energy efficiency. Finally, simulation results validate
the advantage of the proposed energy-efficient scheme compared to the capacity
maximization scheme.Comment: 6 pages, 5 figure
A Survey on Non-Orthogonal Multiple Access for 5G Networks: Research Challenges and Future Trends
Non-orthogonal multiple access (NOMA) is an essential enabling technology for
the fifth generation (5G) wireless networks to meet the heterogeneous demands
on low latency, high reliability, massive connectivity, improved fairness, and
high throughput. The key idea behind NOMA is to serve multiple users in the
same resource block, such as a time slot, subcarrier, or spreading code. The
NOMA principle is a general framework, and several recently proposed 5G
multiple access schemes can be viewed as special cases. This survey provides an
overview of the latest NOMA research and innovations as well as their
applications. Thereby, the papers published in this special issue are put into
the content of the existing literature. Future research challenges regarding
NOMA in 5G and beyond are also discussed.Comment: to appear in IEEE JSAC, 201
Full-Duplex MIMO-OFDM Communication with Self-Energy Recycling
This paper focuses on energy recycling in full-duplex (FD) relaying
multiple-input-multiple-output orthogonal frequency division multiplexing
(OFDM) communication. The loop self-interference (SI) due to full-duplexing is
seen as an opportunity for the energy-constrained relay node to replenish its
energy requirement through wireless power transfer. In forwarding the source
information to the destination, the FD relay can simultaneously harvest energy
from the source wireless transmission and also through energy recycling from
its own transmission. The objective is to maximize the overall spectral
efficiency by designing the optimal power allocation over OFDM sub-carriers and
transmit antennas. Due to a large number of sub-carriers, this design problem
poses a large-scale nonconvex optimization problem involving a few thousand
variables of power allocation, which is very computationally challenging. A new
path-following algorithm is proposed, which converges to an optimal solution.
This algorithm is very efficient since it is based on \textit{closed-form}
calculations. Numerical results for a practical simulation setting show
promising results by achieving high spectral efficiency
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
Multi-Antenna Relay Aided Wireless Physical Layer Security
With growing popularity of mobile Internet, providing secure wireless
services has become a critical issue. Physical layer security (PHY-security)
has been recognized as an effective means to enhance wireless security by
exploiting wireless medium characteristics, e.g., fading, noise, and
interference. A particularly interesting PHY-security technology is cooperative
relay due to the fact that it helps to provide distributed diversity and
shorten access distance. This article offers a tutorial on various
multi-antenna relaying technologies to improve security at physical layer. The
state of the art research results on multi-antenna relay aided PHY-security as
well as some secrecy performance optimization schemes are presented. In
particular, we focus on large-scale MIMO (LS-MIMO) relaying technology, which
is effective to tackle various challenging issues for implementing wireless
PHY-security, such as short-distance interception without eavesdropper channel
state information (CSI) and with imperfect legitimate CSI. Moreover, the future
directions are identified for further enhancement of secrecy performance.Comment: 17 pages, 4 figures, IEEE Communications Magazine, 201
Optimal Transmission Using a Self-sustained Relay in a Full-Duplex MIMO System
This paper investigates wireless information and power transfer in a
full-duplex MIMO relay channel where the self-sustained relay harvests energy
from both source transmit signal and self-interference signal to decode and
forward source information to a destination. We present a novel technique to
jointly optimize power splitting at the relay and precoding design (power
allocation) for both the source and relay transmissions. We formulate a new
convex optimization problem, establish the dual problem via closed-form optimal
primal solutions, and design an efficient primal-dual algorithm to maximize the
achievable throughput. Numerical results demonstrate the benefits of using
multiple transmit and receive antennas in both information decoding and energy
harvesting. We also extend our analysis to the case when channel state
information is only available at receiving nodes and show how our algorithm can
optimize the power splitting at the relay for it to remain self-sustained.
Through analysis and simulation, we show how an optimal combination of
non-uniform power splitting, variable power allocation, and self-interference
power harvesting effectively exploits a full-duplex MIMO system to achieve
significant performance gains over existing uniform power splitting and
half-duplex transmission techniques
Relay Assisted Device-to-Device Communication: Approaches and Issues
Enabling technologies for 5G and future wireless communication have attracted
the interest of industry and research communities. One of such technologies is
Device-to-Device (D2D) communication which exploits user proximity to offer
spectral efficiency, energy efficiency and increased throughput. Data
offloading, public safety communication, context aware communication and
content sharing are some of the use cases for D2D communication. D2D
communication can be direct or through a relay depending on the nature of the
channel in between the D2D devices. Apart from the problem of interference, a
key challenge of relay aided D2D communication is appropriately assigning
relays to a D2D pair while maintaining the QoS requirement of the cellular
users. In this article, relay assisted D2D communication is reviewed and
research issues are highlighted. We also propose matching theory with
incomplete information for relay allocation considering uncertainties which the
mobility of the relay introduces to the set up
Energy Efficient Precoding Design for SWIPT in MIMO Two-Way Relay Networks
In this paper, we study the energy efficiency (EE) maximization problem in
multiple-input multiple-output (MIMO) two-way relay networks with simultaneous
wireless information and power transfer (SWIPT). The network consists of a
multiple-antenna amplify-and-forward relay node which provides bidirectional
communications between two multiple-antenna transceiver nodesComment: 16 pages, 6 figures, to appear in IEEE Transactions on Vehicular
Technolog
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