6 research outputs found
Robust Transmissions in Wireless Powered Multi-Relay Networks with Chance Interference Constraints
In this paper, we consider a wireless powered multi-relay network in which a
multi-antenna hybrid access point underlaying a cellular system transmits
information to distant receivers. Multiple relays capable of energy harvesting
are deployed in the network to assist the information transmission. The hybrid
access point can wirelessly supply energy to the relays, achieving multi-user
gains from signal and energy cooperation. We propose a joint optimization for
signal beamforming of the hybrid access point as well as wireless energy
harvesting and collaborative beamforming strategies of the relays. The
objective is to maximize network throughput subject to probabilistic
interference constraints at the cellular user equipment. We formulate the
throughput maximization with both the time-switching and power-splitting
schemes, which impose very different couplings between the operating parameters
for wireless power and information transfer. Although the optimization problems
are inherently non-convex, they share similar structural properties that can be
leveraged for efficient algorithm design. In particular, by exploiting
monotonicity in the throughput, we maximize it iteratively via customized
polyblock approximation with reduced complexity. The numerical results show
that the proposed algorithms can achieve close to optimal performance in terms
of the energy efficiency and throughput.Comment: 14 pages, 8 figure
Simultaneous Wireless Information and Power Transfer for Decode-and-Forward Multi-Hop Relay Systems in Energy-Constrained IoT Networks
This paper studies a multi-hop decode-and-forward (DF) simultaneous wireless
information and power transfer (SWIPT) system where a source sends data to a
destination with the aid of multi-hop relays which do not depend on an external
energy source. To this end, we apply power splitting (PS) based SWIPT relaying
protocol so that the relays can harvest energy from the received signals from
the previous hop to reliably forward the information of the source to the
destination. We aim to solve two optimization problems relevant to our system
model. First, we minimize the transmit power at the source under the individual
quality-of-service (QoS) threshold constraints of the relays and the
destination nodes by optimizing PS ratios at the relays. The second is to
maximize the minimum system achievable rate by optimizing the PS ratio at each
relay. Based on convex optimization techniques, the globally optimal PS ratio
solution is obtained in closed-form for both problems. By setting the QoS
threshold constraint the same for each node for the source transmit power
problem, we discovered that either the minimum source transmit power or the
maximum system throughput can be found using the same approach. Numerical
results demonstrate the superiority of the proposed optimal SWIPT PS design
over conventional fixed PS ratio schemes.Comment: 14 pages, 14 figures, Accepted for Publication in IEEE Internet of
Things Journa
Robust Transceiver Design for SWIPT DF MIMO Relay Systems With Time-Switching Protocol
In this article, we investigate a dual-hop simultaneous wireless information and power transfer decode-and-forward multiple-input and multiple-output relay communication system, in which the relay node harvests energy based on the radio frequency (RF) signal transmitted from the source node through the time-switching (TS) protocol to decode and forward the re-encoded information to the destination node. With the consideration of the channel estimation error, the joint optimization of the TS factor and source and relay precoding matrices is proposed with robustness against the channel state information mismatch to maximize the mutual information (MI) between the source and destination nodes. We derive the optimal structure of the source and relay precoding matrices to simplify the transceiver optimization problem under fixed and flexible power constraints. Numerical examples demonstrate that the proposed algorithms with robustness provide better MI performance compared to the nonrobust algorithm