1,280 research outputs found
Joint Wireless Information and Energy Transfer in a K-User MIMO Interference Channel
Recently, joint wireless information and energy transfer (JWIET) methods have
been proposed to relieve the battery limitation of wireless devices. However,
the JWIET in a general K-user MIMO interference channel (IFC) has been
unexplored so far. In this paper, we investigate for the first time the JWIET
in K-user MIMO IFC, in which receivers either decode the incoming information
data (information decoding, ID) or harvest the RF energy (energy harvesting,
EH). In the K-user IFC, we consider three different scenarios according to the
receiver mode -- i) multiple EH receivers and a single ID receiver, ii)
multiple IDs and a single EH, and iii) multiple IDs and multiple EHs. For all
scenarios, we have found a common necessary condition of the optimal
transmission strategy and, accordingly, developed the transmission strategy
that satisfies the common necessary condition, in which all the transmitters
transferring energy exploit a rank-one energy beamforming. Furthermore, we have
also proposed an iterative algorithm to optimize the covariance matrices of the
transmitters that transfer information and the powers of the energy beamforming
transmitters simultaneously, and identified the corresponding achievable
rate-energy tradeoff region. Finally, we have shown that by selecting EH
receivers according to their signal-to-leakage-and-harvested energy-ratio
(SLER), we can improve the achievable rate-energy region further.Comment: arXiv admin note: text overlap with arXiv:1303.169
Energy-Efficient NOMA Enabled Heterogeneous Cloud Radio Access Networks
Heterogeneous cloud radio access networks (H-CRANs) are envisioned to be
promising in the fifth generation (5G) wireless networks. H-CRANs enable users
to enjoy diverse services with high energy efficiency, high spectral
efficiency, and low-cost operation, which are achieved by using cloud computing
and virtualization techniques. However, H-CRANs face many technical challenges
due to massive user connectivity, increasingly severe spectrum scarcity and
energy-constrained devices. These challenges may significantly decrease the
quality of service of users if not properly tackled. Non-orthogonal multiple
access (NOMA) schemes exploit non-orthogonal resources to provide services for
multiple users and are receiving increasing attention for their potential of
improving spectral and energy efficiency in 5G networks. In this article a
framework for energy-efficient NOMA H-CRANs is presented. The enabling
technologies for NOMA H-CRANs are surveyed. Challenges to implement these
technologies and open issues are discussed. This article also presents the
performance evaluation on energy efficiency of H-CRANs with NOMA.Comment: This work has been accepted by IEEE Network. Pages 18, Figure
Resource Allocation in Wireless Networks with RF Energy Harvesting and Transfer
Radio frequency (RF) energy harvesting and transfer techniques have recently
become alternative methods to power the next generation of wireless networks.
As this emerging technology enables proactive replenishment of wireless
devices, it is advantageous in supporting applications with quality-of-service
(QoS) requirement. This article focuses on the resource allocation issues in
wireless networks with RF energy harvesting capability, referred to as RF
energy harvesting networks (RF-EHNs). First, we present an overview of the
RF-EHNs, followed by a review of a variety of issues regarding resource
allocation. Then, we present a case study of designing in the receiver
operation policy, which is of paramount importance in the RF-EHNs. We focus on
QoS support and service differentiation, which have not been addressed by
previous literatures. Furthermore, we outline some open research directions.Comment: To appear in IEEE Networ
Improved Rate-Energy Trade-off For SWIPT Using Chordal Distance Decomposition In Interference Alignment Networks
This paper investigates the simultaneous wireless information and power
transfer (SWIPT) precoding scheme for K-user multiple-input-multiple-output
(MIMO) interference channels (IC), for which interference alignment (IA)
schemes provide optimal precoders to achieve full degrees-of-freedom (DoF)
gain. However, harvesting RF energy simultaneously reduces the achievable DoFs.
To study a trade-off between harvested energy and sum rate, the transceiver
design problem is suboptimally formulated in literature via convex relaxations,
which is still computationally intensive, especially for battery limited nodes
running on harvested energy. In this paper, we propose a systematic method
using chordal distance (CD) decomposition to obtain the balanced precoding,
which improves the trade-off. Analysis shows that given the nonnegative value
of CD, the achieved harvested energy for the proposed precoder is higher than
that for perfect IA precoder. Moreover, energy constraints can be achieved,
while maintaining a constant rate loss without losing DoFs via tuning the CD
value and splitting factor. Simulation results verify the analysis and add that
the IA schemes based on max-SINR or mean-squared error are better suited for
SWIPT maximization than subspace or leakage minimization methods
Wireless information and energy transfer in multi-cluster MIMO uplink networks through opportunistic interference alignment
In this paper, we consider a K-cluster (K >= 2) simultaneous wireless information and power transfer (SWIPT) network, where S nodes (S >= 2) are selected from N nodes within each cluster for the uplink information transmission (IT) and the remaining N - S idle nodes are dedicated to energy harvesting (EH). Based on the intra-cluster performance aware (ICPA) philosophy, a pair of opportunistic interference alignment (OIA) schemes, namely the coarse ICPA-OIA (C-ICPA-OIA) and the refined ICPA-OIA (R-ICPA-OIA), are proposed for balancing the sum rate performance achieved and the energy harvested. Specifically, the C-ICPA-OIA treats the overall signal strength within the reference signal subspace (RSS) as a coarse description of the node’s effective signal strength. By comparison, to take full advantage of zero-forcing (ZF) based reception, the R-ICPA-OIA considers the projected signal strength with respect to the orthonormal basis of RSS as a substantially refined description of the node’s effective signal strength. Furthermore, we analyzed the harvested power and the working time of the system. Extensive simulation results validate our theoretical analyses, demonstrating that our schemes outperform the existing OIA schemes
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