399 research outputs found
Heterogeneous Power-Splitting Based Two-Way DF Relaying with Non-Linear Energy Harvesting
Simultaneous wireless information and power transfer (SWIPT) has been
recognized as a promising approach to improving the performance of energy
constrained networks. In this paper, we investigate a SWIPT based three-step
two-way decode-and-forward (DF) relay network with a non-linear energy
harvester equipped at the relay. As most existing works require instantaneous
channel state information (CSI) while CSI is not fully utilized when designing
power splitting (PS) schemes, there exists an opportunity for enhancement by
exploiting CSI for PS design. To this end, we propose a novel heterogeneous PS
scheme, where the PS ratios are dynamically changed according to instantaneous
channel gains. In particular, we derive the closed-form expressions of the
optimal PS ratios to maximize the capacity of the investigated network and
analyze the outage probability with the optimal dynamic PS ratios based on the
non-linear energy harvesting (EH) model. The results provide valuable insights
into the effect of various system parameters, such as transmit power of the
source, source transmission rate, and source to relay distance on the
performance of the investigated network. The results show that our proposed PS
scheme outperforms the existing schemes.Comment: This article has been accepted by IEEE GLOBECOM201
Dynamic asymmetric power splitting scheme for SWIPT based two-way multiplicative AF relaying
Power splitting (PS) scheme design is one of the most
important challenges in simultaneous wireless information and
power transfer (SWIPT) based two-way multiplicative amplifyand-forward
(AF) relay networks. In this letter, we propose
a novel dynamic asymmetric PS (DAPS) scheme to minimize
the system outage probability by exploiting the asymmetric
instantaneous channel gains between the relay node and the
destination nodes. As the formulated optimization problem is
a non-convex problem and difficult to solve, we reformulate it as
a fractional programming problem and propose a Dinkelbachbased
iterative algorithm to obtain the optimal asymmetric PS
ratios. Both the analytical and simulation results demonstrate
that the proposed DAPS scheme with the same channel state
information overhead can significantly reduce the system outage
probability as compared with the existing static symmetric PS
scheme
On the outage performance of SWIPT based three-step two-way DF relay networks
In this paper, we study the outage performance of simultaneous wireless information and power transfer (SWIPT) based three-step two-way decode-and-forward (DF) relay networks, where both power-splitting (PS) and "harvest-thenforward" are employed. In particular, we derive the expressions of terminal-to-terminal (T2T) and system outage probabilities based on a Gaussian-Chebyshev quadrature approximation, and obtain the T2T and system outage capacities. The effects of various system parameters, e.g., the static power allocation ratio at the relay, symmetric PS, as well as asymmetric PS, on the outage performance of the investigated network are examined. It is shown that our derived expression for T2T outage capacity is more accurate than existing analytical results, and that the asymmetric PS achieves a higher system outage capacity than the symmetric one when the channels between the relay node and the terminal nodes have different statistic gains
Rate-Energy Balanced Precoding Design for SWIPT based Two-Way Relay Systems
Simultaneous wireless information and power transfer (SWIPT) technique is a
popular strategy to convey both information and RF energy for harvesting at
receivers. In this regard, we consider a two-way relay system with multiple
users and a multi-antenna relay employing SWIPT strategy, where splitting the
received signal leads to a rate-energy trade-off. In literature, the works on
transceiver design have been studied using computationally intensive and
suboptimal convex relaxation based schemes. In this paper, we study the
balanced precoder design using chordal distance (CD) decomposition, which
incurs much lower complexity, and is flexible to dynamic energy requirements.
It is analyzed that given a non-negative value of CD, the achieved harvested
energy for the proposed balanced precoder is higher than that for the perfect
interference alignment (IA) precoder. The corresponding loss in sum rates is
also analyzed via an upper bound. Simulation results add that the IA schemes
based on mean-squared error are better suited for the SWIPT maximization than
the subspace alignment-based methods.Comment: arXiv admin note: text overlap with arXiv:2101.1216
Optimal combining and performance analysis for two-way EH relay systems with TDBC protocol
In this paper, we investigate a simultaneous wireless information and power transfer (SWIPT) based two-way decode-and-forward (DF) relay network, where time switching (TS) is employed for SWIPT and time division broadcast (TDBC) is employed for two-way relaying. We focus on the design of a combining scheme that decides how the relay combines the signals received from two terminals through a power allocation ratio at the relay. We formulate an optimization problem to minimize the system outage probability and obtain the optimal power allocation ratio in closed form. For the proposed optimal combining scheme, we derive the expression for the system outage probability. Simulation results verify our derived expressions and show that the proposed scheme achieves a lower system outage probability than the existing schemes
Sum throughput maximization for heterogeneous multicell networks with RF-powered relays
This paper considers a heterogeneous multicell network
where the base station (BS) in each cell communicates with
its cell-edge user with the assistance of an amplify-and-forward
relay node. Equipped with a power splitter and a wireless energy
harvester, the relay scavenges RF energy from the received signals to
process and forward the information. In the face of strong intercell
interference and limited radio resources, we develop a resource
allocation scheme that jointly optimizes (i) BS transmit powers,
(ii) power splitting factors for energy harvesting and information
processing at the relays, and (iii) relay transmit powers. To solve the
highly non-convex problem formulation of sum-rate maximization,
we propose to apply the successive convex approximation (SCA)
approach and devise an iterative algorithm based on geometric
programming. The proposed algorithm transforms the nonconvex
problem into a sequence of convex problems, each of which is solved
very efficiently by the interior-point method. We prove that our
developed algorithm converges to an optimal solution that satisfies
the Karush-Kuhn-Tucker conditions of the original nonconvex
problem. Numerical results confirm that our joint optimization
solution substantially improves the network performance, compared
to the existing solution wherein only the received power splitting
factors at the relays are optimizedARC Discovery Projects Grant DP14010113
Towards a Realistic Assessment of Multiple Antenna HCNs: Residual Additive Transceiver Hardware Impairments and Channel Aging
Given the critical dependence of broadcast channels by the accuracy of
channel state information at the transmitter (CSIT), we develop a general
downlink model with zero-forcing (ZF) precoding, applied in realistic
heterogeneous cellular systems with multiple antenna base stations (BSs).
Specifically, we take into consideration imperfect CSIT due to pilot
contamination, channel aging due to users relative movement, and unavoidable
residual additive transceiver hardware impairments (RATHIs). Assuming that the
BSs are Poisson distributed, the main contributions focus on the derivations of
the upper bound of the coverage probability and the achievable user rate for
this general model. We show that both the coverage probability and the user
rate are dependent on the imperfect CSIT and RATHIs. More concretely, we
quantify the resultant performance loss of the network due to these effects. We
depict that the uplink RATHIs have equal impact, but the downlink transmit BS
distortion has a greater impact than the receive hardware impairment of the
user. Thus, the transmit BS hardware should be of better quality than user's
receive hardware. Furthermore, we characterise both the coverage probability
and user rate in terms of the time variation of the channel. It is shown that
both of them decrease with increasing user mobility, but after a specific value
of the normalised Doppler shift, they increase again. Actually, the time
variation, following the Jakes autocorrelation function, mirrors this effect on
coverage probability and user rate. Finally, we consider space division
multiple access (SDMA), single user beamforming (SU-BF), and baseline
single-input single-output (SISO) transmission. A comparison among these
schemes reveals that the coverage by means of SU-BF outperforms SDMA in terms
of coverage.Comment: accepted in IEEE TV
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