141 research outputs found
SWIPT with practical modulation and RF energy harvesting sensitivity
In this paper, we investigate the performance of
simultaneous wireless information and power transfer (SWIPT)
in a point-to-point system, adopting practical M-ary modulation.
We take into account the fact that the receiver’s radio-frequency
(RF) energy harvesting circuit can only harvest energy when
the received signal power is greater than a certain sensitivity
level. For both power-splitting (PS) and time-switching (TS)
schemes, we derive the energy harvesting performance as well
as the information decoding performance for the Nakagamim
fading channel. We also analyze the performance tradeoff
between energy harvesting and information decoding by studying
an optimization problem, which maximizes the information
decoding performance and satisfies a constraint on the minimum
harvested energy. Our analysis shows that (i) for the PS scheme,
modulations with high peak-to-average power ratio achieve better
energy harvesting performance, (ii) for the TS scheme, it is
desirable to concentrate the power for wireless power transfer
in order to minimize the non-harvested energy caused by the
RF energy harvesting sensitivity level, and (iii) channel fading is
beneficial for energy harvesting in both PS and TS schemes.ARC Discovery Projects Grant DP14010113
Wireless Information and Power Transfer: Architecture Design and Rate-Energy Tradeoff
Simultaneous information and power transfer over the wireless channels
potentially offers great convenience to mobile users. Yet practical receiver
designs impose technical constraints on its hardware realization, as practical
circuits for harvesting energy from radio signals are not yet able to decode
the carried information directly. To make theoretical progress, we propose a
general receiver operation, namely, dynamic power splitting (DPS), which splits
the received signal with adjustable power ratio for energy harvesting and
information decoding, separately. Three special cases of DPS, namely, time
switching (TS), static power splitting (SPS) and on-off power splitting (OPS)
are investigated. The TS and SPS schemes can be treated as special cases of
OPS. Moreover, we propose two types of practical receiver architectures,
namely, separated versus integrated information and energy receivers. The
integrated receiver integrates the front-end components of the separated
receiver, thus achieving a smaller form factor. The rate-energy tradeoff for
the two architectures are characterized by a so-called rate-energy (R-E)
region. The optimal transmission strategy is derived to achieve different
rate-energy tradeoffs. With receiver circuit power consumption taken into
account, it is shown that the OPS scheme is optimal for both receivers. For the
ideal case when the receiver circuit does not consume power, the SPS scheme is
optimal for both receivers. In addition, we study the performance for the two
types of receivers under a realistic system setup that employs practical
modulation. Our results provide useful insights to the optimal practical
receiver design for simultaneous wireless information and power transfer
(SWIPT).Comment: to appear in IEEE Transactions on Communication
Fundamentals of Wireless Information and Power Transfer: From RF Energy Harvester Models to Signal and System Designs
Radio waves carry both energy and information simultaneously. Nevertheless,
Radio-Frequency (RF) transmission of these quantities have traditionally been
treated separately. Currently, we are experiencing a paradigm shift in wireless
network design, namely unifying wireless transmission of information and power
so as to make the best use of the RF spectrum and radiations as well as the
network infrastructure for the dual purpose of communicating and energizing. In
this paper, we review and discuss recent progress on laying the foundations of
the envisioned dual purpose networks by establishing a signal theory and design
for Wireless Information and Power Transmission (WIPT) and identifying the
fundamental tradeoff between conveying information and power wirelessly. We
start with an overview of WIPT challenges and technologies, namely Simultaneous
Wireless Information and Power Transfer (SWIPT),Wirelessly Powered
Communication Network (WPCN), and Wirelessly Powered Backscatter Communication
(WPBC). We then characterize energy harvesters and show how WIPT signal and
system designs crucially revolve around the underlying energy harvester model.
To that end, we highlight three different energy harvester models, namely one
linear model and two nonlinear models, and show how WIPT designs differ for
each of them in single-user and multi-user deployments. Topics discussed
include rate-energy region characterization, transmitter and receiver
architecture, waveform design, modulation, beamforming and input distribution
optimizations, resource allocation, and RF spectrum use. We discuss and check
the validity of the different energy harvester models and the resulting signal
theory and design based on circuit simulations, prototyping and
experimentation. We also point out numerous directions that are promising for
future research.Comment: guest editor-authored tutorial paper submitted to IEEE JSAC special
issue on wireless transmission of information and powe
Joint Interleaver and Modulation Design For Multi-User SWIPT-NOMA
Radio frequency (RF) signals can be relied upon for conventional wireless information transfer (WIT) and for challenging wireless power transfer (WPT), which triggers the significant research interest in the topic of simultaneous wireless information and power transfer (SWIPT). By further exploiting the advanced non-orthogonal-multiple-access (NOMA) technique, we are capable of improving the spectrum efficiency of the resource-limited SWIPT system. In our SWIPT system, a hybrid access point (H-AP) superimposes the modulated symbols destined to multiple WIT users by exploiting the power-domain NOMA, while WPT users are capable of harvesting the energy carried by the superposition symbols. In order to maximize the amount of energy transferred to the WPT users, we propose a joint design of the energy interleaver and the constellation rotation-based modulator in the symbol-block level by constructively superimposing the symbols destined to the WIT users in the power domain. Furthermore, a transmit power allocation scheme is proposed to guarantee the symbol-error-ratio (SER) of all the WIT users. By considering the sensitivity of practical energy harvesters, simulation results demonstrate that our scheme is capable of substantially increasing the WPT performance without any remarkable degradation of the WIT performance
Unary Coding Design for Simultaneous Wireless Information and Power Transfer with Practical M-QAM
Relying on the propagation of modulated radio-frequency (RF) signals, we can achieve simultaneous wireless information and power transfer (SWIPT) to support low-power communication devices. In this paper, we proposed a unary coding based SWIPT encoder by considering a practical M-QAM. Markov chains are exploited for characterising coherent binary information source and for modelling the generation process of modulated symbols. Therefore, both mutual information and the average energy harvesting performance at the SWIPT receiver are analysed in semi-closed-form. With the aid of the genetic algorithm, the sub-optimal codeword distribution of the coded information source is obtained by maximising the average energy harvesting performance, while satisfying the requirement of the mutual information. Simulation results demonstrate the advantage of the SWIPT encoder. Moreover, a higher-level unary code and a lower-order M-QAM results in higher WPT performance, when the maximum transmit power of the modulated symbol is fixed
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