456 research outputs found
An Overview of Physical Layer Security with Finite-Alphabet Signaling
Providing secure communications over the physical layer with the objective of
achieving perfect secrecy without requiring a secret key has been receiving
growing attention within the past decade. The vast majority of the existing
studies in the area of physical layer security focus exclusively on the
scenarios where the channel inputs are Gaussian distributed. However, in
practice, the signals employed for transmission are drawn from discrete signal
constellations such as phase shift keying and quadrature amplitude modulation.
Hence, understanding the impact of the finite-alphabet input constraints and
designing secure transmission schemes under this assumption is a mandatory step
towards a practical implementation of physical layer security. With this
motivation, this article reviews recent developments on physical layer security
with finite-alphabet inputs. We explore transmit signal design algorithms for
single-antenna as well as multi-antenna wiretap channels under different
assumptions on the channel state information at the transmitter. Moreover, we
present a review of the recent results on secure transmission with discrete
signaling for various scenarios including multi-carrier transmission systems,
broadcast channels with confidential messages, cognitive multiple access and
relay networks. Throughout the article, we stress the important behavioral
differences of discrete versus Gaussian inputs in the context of the physical
layer security. We also present an overview of practical code construction over
Gaussian and fading wiretap channels, and we discuss some open problems and
directions for future research.Comment: Submitted to IEEE Communications Surveys & Tutorials (1st Revision
Index Modulation-based Information Harvesting for Far-Field RF Power Transfer
While wireless information transmission (WIT) is evolving into its sixth
generation (6G), maintaining terminal operations that rely on limited battery
capacities has become one of the most paramount challenges for
Internet-of-Things (IoT) platforms. In this respect, there exists a growing
interest in energy harvesting technology from ambient resources, and wireless
power transfer (WPT) can be the key solution towards enabling battery-less
infrastructures referred to as zero-power communication technology. Indeed,
eclectic integration approaches between WPT and WIT mechanisms are becoming a
vital necessity to limit the need for replacing batteries. Beyond the
conventional separation between data and power components of the emitted
waveforms, as in simultaneous wireless information and power transfer (SWIPT)
mechanisms, a novel protocol referred to as information harvesting (IH) has
recently emerged. IH leverages existing WPT mechanisms for data communication
by incorporating index modulation (IM) techniques on top of the existing
far-field power transfer mechanism. In this paper, a unified framework for the
IM-based IH mechanisms has been presented where the feasibility of various IM
techniques are evaluated based on different performance metrics. The presented
results demonstrate the substantial potential to enable data communication
within existing far-field WPT systems, particularly in the context of
next-generation IoT wireless networks.Comment: 13 pages, 9 figure
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