2,152 research outputs found
Energy-Efficient Power Allocation in OFDM Systems with Wireless Information and Power Transfer
This paper considers an orthogonal frequency division multiplexing (OFDM)
downlink point-to-point system with simultaneous wireless information and power
transfer. It is assumed that the receiver is able to harvest energy from noise,
interference, and the desired signals.
We study the design of power allocation algorithms maximizing the energy
efficiency of data transmission (bit/Joule delivered to the receiver). In
particular, the algorithm design is formulated as a high-dimensional non-convex
optimization problem which takes into account the circuit power consumption,
the minimum required data rate, and a constraint on the minimum power delivered
to the receiver. Subsequently, by exploiting the properties of nonlinear
fractional programming, the considered non-convex optimization problem, whose
objective function is in fractional form, is transformed into an equivalent
optimization problem having an objective function in subtractive form, which
enables the derivation of an efficient iterative power allocation algorithm. In
each iteration, the optimal power allocation solution is derived based on dual
decomposition and a one-dimensional search. Simulation results illustrate that
the proposed iterative power allocation algorithm converges to the optimal
solution, and unveil the trade-off between energy efficiency, system capacity,
and wireless power transfer: (1) In the low transmit power regime, maximizing
the system capacity may maximize the energy efficiency. (2) Wireless power
transfer can enhance the energy efficiency, especially in the interference
limited regime.Comment: 6 pages, Accepted for presentation at the IEEE International
Conference on Communications (ICC) 201
Prototyping and Experimentation of a Closed-Loop Wireless Power Transmission with Channel Acquisition and Waveform Optimization
A systematic design of adaptive waveform for Wireless Power Transfer (WPT)
has recently been proposed and shown through simulations to lead to significant
performance benefits compared to traditional non-adaptive and heuristic
waveforms. In this study, we design the first prototype of a closed-loop
wireless power transfer system with adaptive waveform optimization based on
Channel State Information acquisition. The prototype consists of three
important blocks, namely the channel estimator, the waveform optimizer, and the
energy harvester. Software Defined Radio (SDR) prototyping tools are used to
implement a wireless power transmitter and a channel estimator, and a voltage
doubler rectenna is designed to work as an energy harvester. A channel adaptive
waveform with 8 sinewaves is shown through experiments to improve the average
harvested DC power at the rectenna output by 9.8% to 36.8% over a non-adaptive
design with the same number of sinewaves.Comment: accepted for publication in IEEE WPTC 201
MIMO-OFDM Based Energy Harvesting Cooperative Communications Using Coalitional Game Algorithm
This document is the Accepted Manuscript version. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper, we consider the problem of cooperative communication between relays and base station in an advanced MIMO-OFDM framework, under the assumption that the relays are supplied by electric power drawn from energy harvesting (EH) sources. In particular, we focus on the relay selection, with the goal to guarantee the required performance in terms of capacity. In order to maximize the data throughput under the EH constraint, we model the transmission scheme as a non-transferable coalition formation game, with characteristic function based on an approximated capacity expression. Then, we introduce a powerful mathematical tool inherent to coalitional game theory, namely: the Shapley value (Sv) to provide a reliable solution concept to the game. The selected relays will form a virtual dynamically-configuredMIMO network that is able to transmit data to destination using efficient space-time coding techniques. Numerical results, obtained by simulating the EH-powered cooperativeMIMO-OFDMtransmission with Algebraic Space-Time Coding (ASTC), prove that the proposed coalitional game-based relay selection allows to achieve performance very close to that obtained by the same system operated by guaranteed power supply. The proposed methodology is finally compared with some recent related state-of-the-art techniques showing clear advantages in terms of link performance and goodput.Peer reviewe
Energy-Efficient Resource Allocation in Multiuser OFDM Systems with Wireless Information and Power Transfer
In this paper, we study the resource allocation algorithm design for
multiuser orthogonal frequency division multiplexing (OFDM) downlink systems
with simultaneous wireless information and power transfer. The algorithm design
is formulated as a non-convex optimization problem for maximizing the energy
efficiency of data transmission (bit/Joule delivered to the users). In
particular, the problem formulation takes into account the minimum required
system data rate, heterogeneous minimum required power transfers to the users,
and the circuit power consumption. Subsequently, by exploiting the method of
time-sharing and the properties of nonlinear fractional programming, the
considered non-convex optimization problem is solved using an efficient
iterative resource allocation algorithm. For each iteration, the optimal power
allocation and user selection solution are derived based on Lagrange dual
decomposition. Simulation results illustrate that the proposed iterative
resource allocation algorithm achieves the maximum energy efficiency of the
system and reveal how energy efficiency, system capacity, and wireless power
transfer benefit from the presence of multiple users in the system.Comment: 6 pages. The paper has been accepted for publication at the IEEE
Wireless Communications and Networking Conference (WCNC) 2013, Shanghai,
China, Apr. 201
Wireless Information and Energy Transfer for Two-Hop Non-Regenerative MIMO-OFDM Relay Networks
This paper investigates the simultaneous wireless information and energy
transfer for the non-regenerative multipleinput multiple-output orthogonal
frequency-division multiplexing (MIMO-OFDM) relaying system. By considering two
practical receiver architectures, we present two protocols, time switchingbased
relaying (TSR) and power splitting-based relaying (PSR). To explore the system
performance limit, we formulate two optimization problems to maximize the
end-to-end achievable information rate with the full channel state information
(CSI) assumption. Since both problems are non-convex and have no known solution
method, we firstly derive some explicit results by theoretical analysis and
then design effective algorithms for them. Numerical results show that the
performances of both protocols are greatly affected by the relay position.
Specifically, PSR and TSR show very different behaviors to the variation of
relay position. The achievable information rate of PSR monotonically decreases
when the relay moves from the source towards the destination, but for TSR, the
performance is relatively worse when the relay is placed in the middle of the
source and the destination. This is the first time to observe such a
phenomenon. In addition, it is also shown that PSR always outperforms TSR in
such a MIMO-OFDM relaying system. Moreover, the effect of the number of
antennas and the number of subcarriers are also discussed.Comment: 16 pages, 12 figures, to appear in IEEE Selected Areas in
Communication
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