679 research outputs found
Secrecy Wireless Information and Power Transfer with MISO Beamforming
The dual use of radio signals for simultaneous wireless information and power
transfer (SWIPT) has recently drawn significant attention. To meet the
practical requirement that energy receivers (ERs) operate with significantly
higher received power as compared to information receivers (IRs), ERs need to
be deployed in more proximity to the transmitter than IRs. However, due to the
broadcast nature of wireless channels, one critical issue arises that the
messages sent to IRs can be eavesdropped by ERs, which possess better channels
from the transmitter. In this paper, we address this new secrecy communication
problem in a multiuser multiple-input single-output (MISO) SWIPT system where
one multi-antenna transmitter sends information and energy simultaneously to an
IR and multiple ERs, each with one single antenna. To optimally design transmit
beamforming vectors and their power allocation, two problems are investigated
with different aims: the first problem maximizes the secrecy rate for IR
subject to individual harvested energy constraints of ERs, while the second
problem maximizes the weighted sum-energy transferred to ERs subject to a
secrecy rate constraint for IR. We solve these two non-convex problems
optimally by reformulating each of them into a two-stage problem. First, by
fixing the signal-to-interference-plus-noise ratio (SINR) target for ERs (for
the first problem) or IR (for the second problem), we obtain the optimal
beamforming and power allocation solution by applying the technique of
semidefinite relaxation (SDR). Then, the original problems are solved by a
one-dimension search over the optimal SINR target for ERs or IR. Furthermore,
for each of the two studied problems, suboptimal solutions of lower complexity
are also proposed in which the information and energy beamforming vectors are
separately designed with their power allocation.Comment: accepted by IEEE Transactions on Signal Processing. Longer version of
arXiv:1306.096
Secure Beamforming For MIMO Broadcasting With Wireless Information And Power Transfer
This paper considers a basic MIMO information-energy (I-E) broadcast system,
where a multi-antenna transmitter transmits information and energy
simultaneously to a multi-antenna information receiver and a dual-functional
multi-antenna energy receiver which is also capable of decoding information.
Due to the open nature of wireless medium and the dual purpose of information
and energy transmission, secure information transmission while ensuring
efficient energy harvesting is a critical issue for such a broadcast system.
Assuming that physical layer security techniques are applied to the system to
ensure secure transmission from the transmitter to the information receiver, we
study beamforming design to maximize the achievable secrecy rate subject to a
total power constraint and an energy harvesting constraint. First, based on
semidefinite relaxation, we propose global optimal solutions to the secrecy
rate maximization (SRM) problem in the single-stream case and a specific
full-stream case where the difference of Gram matrices of the channel matrices
is positive semidefinite. Then, we propose a simple iterative algorithm named
inexact block coordinate descent (IBCD) algorithm to tackle the SRM problem of
general case with arbitrary number of streams. We proves that the IBCD
algorithm can monotonically converge to a Karush-Kuhn-Tucker (KKT) solution to
the SRM problem. Furthermore, we extend the IBCD algorithm to the joint
beamforming and artificial noise design problem. Finally, simulations are
performed to validate the performance of the proposed beamforming algorithms.Comment: Submitted to journal for possible publication. First submission to
arXiv Mar. 14 201
Beamforming and Power Splitting Designs for AN-aided Secure Multi-user MIMO SWIPT Systems
In this paper, an energy harvesting scheme for a multi-user
multiple-input-multiple-output (MIMO) secrecy channel with artificial noise
(AN) transmission is investigated. Joint optimization of the transmit
beamforming matrix, the AN covariance matrix, and the power splitting ratio is
conducted to minimize the transmit power under the target secrecy rate, the
total transmit power, and the harvested energy constraints. The original
problem is shown to be non-convex, which is tackled by a two-layer
decomposition approach. The inner layer problem is solved through semi-definite
relaxation, and the outer problem, on the other hand, is shown to be a single-
variable optimization that can be solved by one-dimensional (1- D) line search.
To reduce computational complexity, a sequential parametric convex
approximation (SPCA) method is proposed to find a near-optimal solution. The
work is then extended to the imperfect channel state information case with
norm-bounded channel errors. Furthermore, tightness of the relaxation for the
proposed schemes are validated by showing that the optimal solution of the
relaxed problem is rank-one. Simulation results demonstrate that the proposed
SPCA method achieves the same performance as the scheme based on 1-D but with
much lower complexity.Comment: 12 pages, 6 figures, submitted for possible publicatio
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