435 research outputs found
Regenerative and Adaptive schemes Based on Network Coding for Wireless Relay Network
Recent technological advances in wireless communications offer new
opportunities and challenges for relay network.To enhance system performance,
Demodulate-Network Coding (Dm-NC) scheme has been examined at relay node; it
works directly to De-map the received signals and after that forward the
mixture to the destination. Simulation analysis has been proven that the
performance of Dm-NC has superiority over analog-NC. In addition, the
Quantize-Decode-NC scheme (QDF-NC) has been introduced. The presented
simulation results clearly provide that the QDF-NC perform better than
analog-NC. The toggle between analogNC and QDF-NC is simulated in order to
investigate delay and power consumption reduction at relay node.Comment: 11 pages, 8 figures, International Journal of Computer Networks &
Communications (IJCNC), Vol.4, No.3, May 201
Symbol-level and Multicast Precoding for Multiuser Multiantenna Downlink: A Survey, Classification and Challenges
Precoding has been conventionally considered as an effective means of
mitigating the interference and efficiently exploiting the available in the
multiantenna downlink channel, where multiple users are simultaneously served
with independent information over the same channel resources. The early works
in this area were focused on transmitting an individual information stream to
each user by constructing weighted linear combinations of symbol blocks
(codewords). However, more recent works have moved beyond this traditional view
by: i) transmitting distinct data streams to groups of users and ii) applying
precoding on a symbol-per-symbol basis. In this context, the current survey
presents a unified view and classification of precoding techniques with respect
to two main axes: i) the switching rate of the precoding weights, leading to
the classes of block- and symbol-level precoding, ii) the number of users that
each stream is addressed to, hence unicast-/multicast-/broadcast- precoding.
Furthermore, the classified techniques are compared through representative
numerical results to demonstrate their relative performance and uncover
fundamental insights. Finally, a list of open theoretical problems and
practical challenges are presented to inspire further research in this area.Comment: Submitted to IEEE Communications Surveys & Tutorial
Relay selection for multiple access relay channel with decode-forward and analog network coding
This paper presents a relay selection for decode-and-forward based on network
coding (DF-NC) and analog-NC protocols in general scheme of cellular network
system. In the propose scheme the two source node simultaneously transmit their
own information to all the relays as well as the destination node, and then, a
single relay i.e. best with a minimum symbol error rate (SER) will be selected
to forward the new version of the received signal. Simulation results show
that, the DF-NC scheme with considerable performance has exactness over
analog-NC scheme. To improve the system performance, optimal power allocation
between the two sources and the best relay is determined based on the
asymptotic SER. By increasing the number of relays node, the optimum power
allocation achieve better performance than asymptotic SER.Comment: 11 pages, 5 figures; International Journal of Distributed and
Parallel Systems (IJDPS) Vol.3, No.2, March 201
Reliable Physical Layer Network Coding
When two or more users in a wireless network transmit simultaneously, their
electromagnetic signals are linearly superimposed on the channel. As a result,
a receiver that is interested in one of these signals sees the others as
unwanted interference. This property of the wireless medium is typically viewed
as a hindrance to reliable communication over a network. However, using a
recently developed coding strategy, interference can in fact be harnessed for
network coding. In a wired network, (linear) network coding refers to each
intermediate node taking its received packets, computing a linear combination
over a finite field, and forwarding the outcome towards the destinations. Then,
given an appropriate set of linear combinations, a destination can solve for
its desired packets. For certain topologies, this strategy can attain
significantly higher throughputs over routing-based strategies. Reliable
physical layer network coding takes this idea one step further: using
judiciously chosen linear error-correcting codes, intermediate nodes in a
wireless network can directly recover linear combinations of the packets from
the observed noisy superpositions of transmitted signals. Starting with some
simple examples, this survey explores the core ideas behind this new technique
and the possibilities it offers for communication over interference-limited
wireless networks.Comment: 19 pages, 14 figures, survey paper to appear in Proceedings of the
IEE
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
Optimisation of relay placement in wireless butterfly networks
As a typical model of multicast network, wireless butterfly networks (WBNs) have been studied for modelling the scenario when two source nodes wish to convey data to two destination nodes via an intermediary node namely relay node. In the context of wireless communications, when receiving two data packets from the two source nodes, the relay node can employ either physical-layer network coding or analogue network coding on the combined packet prior to forwarding to the two destination nodes. Evaluating the energy efficiency of these combination approaches, energy-delay trade-off (EDT) is worth to be investigated and the relay placement should be taken into account in the practical network design. This chapter will first investigate the EDT of network coding in the WBNs. Based on the derived EDT, algorithms that optimize the relay position will be developed to either minimize the transmission delay or minimize the energy consumption subject to constraints on power allocation and location of nodes. Furthermore, considering an extended model of the WBN, the relay placement will be studied for a general wireless multicast network with multiple source, relay and destination nodes
Analysis of Network Coding Schemes for Differential Chaos Shift Keying Communication System
In this paper we design network coding schemes for Differential Chaos Shift
Keying (DCSK) modulation. In this work, non-coherent chaos-based communication
system is used due to its simplicity and robustness to multipath propagation
effects, while dispensing with any channel state information knowledge at the
receiver. We propose a relay network using network coding and DCSK, where we
first present a Physical layer Network Coding (PNC) scheme with two users,
and , sharing the same spreading code and bandwidth,
while synchronously transmitting their signals to the relay node .
We show that the main drawback of this design in multipath channels is the high
level of interference in the resultant signal, which severely degrades the
system performance. Hence, in order to address this problem, we propose two
coding schemes, which separate the users' signals in the frequency or the time
domains. We show also in this paper that the performance of the Analog Network
Coding (ANC) with DCSK modulation suffers from the same interference problem as
the PNC scheme. We present the analytical bit error rate performance for
multipath Rayleigh fading channel for the different scenarios and we analyse
these schemes in terms of complexity, throughput and link spectral efficiency.Comment: Submitted for potential publication (journal paper
A Survey on Legacy and Emerging Technologies for Public Safety Communications
Effective emergency and natural disaster management depend on the efficient
mission-critical voice and data communication between first responders and
victims. Land Mobile Radio System (LMRS) is a legacy narrowband technology used
for critical voice communications with limited use for data applications.
Recently Long Term Evolution (LTE) emerged as a broadband communication
technology that has a potential to transform the capabilities of public safety
technologies by providing broadband, ubiquitous, and mission-critical voice and
data support. For example, in the United States, FirstNet is building a
nationwide coast-to-coast public safety network based of LTE broadband
technology. This paper presents a comparative survey of legacy and the
LTE-based public safety networks, and discusses the LMRS-LTE convergence as
well as mission-critical push-to-talk over LTE. A simulation study of LMRS and
LTE band class 14 technologies is provided using the NS-3 open source tool. An
experimental study of APCO-25 and LTE band class 14 is also conducted using
software-defined radio, to enhance the understanding of the public safety
systems. Finally, emerging technologies that may have strong potential for use
in public safety networks are reviewed.Comment: Accepted at IEEE Communications Surveys and Tutorial
Device-to-Device Communication in Cellular Networks: A Survey
A constant need to increase the network capacity for meeting the growing
demands of the subscribers has led to the evolution of cellular communication
networks from the first generation (1G) to the fifth generation (5G). There
will be billions of connected devices in the near future. Such a large number
of connections are expected to be heterogeneous in nature, demanding higher
data rates, lesser delays, enhanced system capacity and superior throughput.
The available spectrum resources are limited and need to be flexibly used by
the mobile network operators (MNOs) to cope with the rising demands. An
emerging facilitator of the upcoming high data rate demanding next generation
networks (NGNs) is device-to-device (D2D) communication. An extensive survey on
device-to-device (D2D) communication has been presented in this paper,
including the plus points it offers, the key open issues associated with it
like peer discovery, resource allocation etc, demanding special attention of
the research community, some of its integrant technologies like millimeter wave
D2D (mmWave), ultra dense networks (UDNs), cognitive D2D, handover procedure in
D2D and its numerous use cases. Architecture is suggested aiming to fulfill all
the subscriber demands in an optimal manner. The Appendix mentions some ongoing
standardization activities and research projects of D2D communication.Comment: Accepted In JNCA2016 Elsevie
A Tutorial on Interference Exploitation via Symbol-Level Precoding: Overview, State-of-the-Art and Future Directions
IEEE Interference is traditionally viewed as a performance limiting factor in wireless communication systems, which is to be minimized or mitigated. Nevertheless, a recent line of work has shown that by manipulating the interfering signals such that they add up constructively at the receiver side, known interference can be made beneficial and further improve the system performance in a variety of wireless scenarios, achieved by symbol-level precoding (SLP). This paper aims to provide a tutorial on interference exploitation techniques from the perspective of precoding design in a multi-antenna wireless communication system, by beginning with the classification of constructive interference (CI) and destructive interference (DI). The definition for CI is presented and the corresponding mathematical characterization is formulated for popular modulation types, based on which optimization-based precoding techniques are discussed. In addition, the extension of CI precoding to other application scenarios as well as for hardware efficiency is also described. Proof-of-concept testbeds are demonstrated for the potential practical implementation of CI precoding, and finally a list of open problems and practical challenges are presented to inspire and motivate further research directions in this area
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