2,351 research outputs found
MIMO Broadcasting for Simultaneous Wireless Information and Power Transfer
Wireless power transfer (WPT) is a promising new solution to provide
convenient and perpetual energy supplies to wireless networks. In practice, WPT
is implementable by various technologies such as inductive coupling, magnetic
resonate coupling, and electromagnetic (EM) radiation, for
short-/mid-/long-range applications, respectively. In this paper, we consider
the EM or radio signal enabled WPT in particular. Since radio signals can carry
energy as well as information at the same time, a unified study on simultaneous
wireless information and power transfer (SWIPT) is pursued. Specifically, this
paper studies a multiple-input multiple-output (MIMO) wireless broadcast system
consisting of three nodes, where one receiver harvests energy and another
receiver decodes information separately from the signals sent by a common
transmitter, and all the transmitter and receivers may be equipped with
multiple antennas. Two scenarios are examined, in which the information
receiver and energy receiver are separated and see different MIMO channels from
the transmitter, or co-located and see the identical MIMO channel from the
transmitter. For the case of separated receivers, we derive the optimal
transmission strategy to achieve different tradeoffs for maximal information
rate versus energy transfer, which are characterized by the boundary of a
so-called rate-energy (R-E) region. For the case of co-located receivers, we
show an outer bound for the achievable R-E region due to the potential
limitation that practical energy harvesting receivers are not yet able to
decode information directly. Under this constraint, we investigate two
practical designs for the co-located receiver case, namely time switching and
power splitting, and characterize their achievable R-E regions in comparison to
the outer bound.Comment: The longer version of a paper to appear in IEEE Transactions on
Wireless Communication
Intelligent Reflecting Surface Aided MIMO Broadcasting for Simultaneous Wireless Information and Power Transfer
An intelligent reflecting surface (IRS) is invoked for enhancing the energy harvesting performance of a simultaneous wireless information and power transfer (SWIPT) aided system. Specifically, an IRS-assisted SWIPT system is considered, where a multi-antenna aided base station (BS) communicates with several multi-antenna assisted information receivers (IRs), while guaranteeing the energy harvesting requirement of the energy receivers (ERs). To maximize the weighted sum rate (WSR) of IRs, the transmit precoding (TPC) matrices of the BS and passive phase shift matrix of the IRS should be jointly optimized. To tackle this challenging optimization problem, we first adopt the classic block coordinate descent (BCD) algorithm for decoupling the original optimization problem into several subproblems and alternatively optimize the TPC matrices and the phase shift matrix. For each subproblem, we provide a low-complexity iterative algorithm, which is guaranteed to converge to the Karush-Kuhn-Tucker (KKT) point of each subproblem. The BCD algorithm is rigorously proved to converge to the KKT point of the original problem. We also conceive a feasibility checking method to study its feasibility. Our extensive simulation results confirm that employing IRSs in SWIPT beneficially enhances the system performance and the proposed BCD algorithm converges rapidly, which is appealing for practical applications
Recent Advances in Joint Wireless Energy and Information Transfer
In this paper, we provide an overview of the recent advances in
microwave-enabled wireless energy transfer (WET) technologies and their
applications in wireless communications. Specifically, we divide our
discussions into three parts. First, we introduce the state-of-the-art WET
technologies and the signal processing techniques to maximize the energy
transfer efficiency. Then, we discuss an interesting paradigm named
simultaneous wireless information and power transfer (SWIPT), where energy and
information are jointly transmitted using the same radio waveform. At last, we
review the recent progress in wireless powered communication networks (WPCN),
where wireless devices communicate using the power harvested by means of WET.
Extensions and future directions are also discussed in each of these areas.Comment: Conference submission accepted by ITW 201
Throughput Optimization for Massive MIMO Systems Powered by Wireless Energy Transfer
This paper studies a wireless-energy-transfer (WET) enabled massive
multiple-input-multiple-output (MIMO) system (MM) consisting of a hybrid
data-and-energy access point (H-AP) and multiple single-antenna users. In the
WET-MM system, the H-AP is equipped with a large number of antennas and
functions like a conventional AP in receiving data from users, but additionally
supplies wireless power to the users. We consider frame-based transmissions.
Each frame is divided into three phases: the uplink channel estimation (CE)
phase, the downlink WET phase, as well as the uplink wireless information
transmission (WIT) phase. Firstly, users use a fraction of the previously
harvested energy to send pilots, while the H-AP estimates the uplink channels
and obtains the downlink channels by exploiting channel reciprocity. Next, the
H-AP utilizes the channel estimates just obtained to transfer wireless energy
to all users in the downlink via energy beamforming. Finally, the users use a
portion of the harvested energy to send data to the H-AP simultaneously in the
uplink (reserving some harvested energy for sending pilots in the next frame).
To optimize the throughput and ensure rate fairness, we consider the problem of
maximizing the minimum rate among all users. In the large- regime, we obtain
the asymptotically optimal solutions and some interesting insights for the
optimal design of WET-MM system. We define a metric, namely, the massive MIMO
degree-of-rate-gain (MM-DoRG), as the asymptotic UL rate normalized by
. We show that the proposed WET-MM system is optimal in terms of
MM-DoRG, i.e., it achieves the same MM-DoRG as the case with ideal CE.Comment: 15 double-column pages, 6 figures, 1 table, to appear in IEEE JSAC in
February 2015, special issue on wireless communications powered by energy
harvesting and wireless energy transfe
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
Towards Optimal Energy Harvesting Receiver Design in MIMO Systems
In this paper, we investigate a multiple-input multiple-output (MIMO) system
with simultaneous information detection (ID) and energy harvesting (EH)
receiver. This point-to-point system operates in the vicinity of active
interfering nodes. The receiver performs power splitting where a portion of
received signal undergoes analog energy harvesting circuitry. Further, the
information content of the other portion is extracted after performing digital
beamforming. In this MIMO system, information carrier eigen-modes are not
necessarily the eigen-modes with the strongest energy level. Hence, it is
beneficial to perform independent beamforming at the receiver of MIMO-P2P
channel. Here, we utilize a hybrid analog/digital beamforming for the purpose
of simultaneous ID and EH in such scenarios. This design, provides extra design
degrees-of-freedom in eigen-mode selection for ID and EH purposes
independently. Worst-case performance of this receiver structure is discussed.
Finally, its benefits is compared to the classical receiver structure and the
gains are highlighted
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