153 research outputs found
Wireless Powered Cooperative Relaying using NOMA with Imperfect CSI
The impact of imperfect channel state (CSI) information in an energy
harvesting (EH) cooperative non-orthogonal multiple access (NOMA) network,
consisting of a source, two users, and an EH relay is investigated in this
paper. The relay is not equipped with a fixed power source and acts as a
wireless powered node to help signal transmission to the users. Closed-form
expressions for the outage probability of both users are derived under
imperfect CSI for two different power allocation strategies namely fixed and
dynamic power allocation. Monte Carlo simulations are used to numerically
evaluate the effect of imperfect CSI. These results confirm the theoretical
outage analysis and show that NOMA can outperform orthogonal multiple access
even with imperfect CSI.Comment: 6 pages, 6 figures, accepted in IEEE GLOBECOM 2018 NOMA Worksho
Minimizing Outage Probability by Exploiting CSI in Wireless Powered Cooperative Networks
In this work, we address the relay selection problem for the wireless powered
communication networks, where the relays harvest energy from the source radio
frequency signals. A single source-destination pair is considered without a
direct link. The connecting relay nodes are equipped with storage batteries of
infinite size. We assume that the channel state information (CSI) on the
source-relay link is available at the relay nodes. Depending on the
availability of the CSI on the relay-destination link at the relay node, we
propose different relay selection schemes and evaluate the outage probability.
The availability of the CSI at the relay node on the relay-destination link
considerably improves the performance due to additional flexibility in the
relay selection mechanism. We numerically quantify the performance for the
proposed schemes and compare the outage probability for fixed and equal number
of wireless powered forwarding relays.Comment: accepted in IEEE Globecom 201
Trading Wireless Information and Power Transfer: Relay Selection to Minimize the Outage Probability
This paper studies the outage probability minimization problem for a multiple
relay network with energy harvesting constraints. The relays are hybrid nodes
used for simultaneous wireless information and power transfer from the source
radio frequency (RF) signals. There is a trade-off associated with the amount
of time a relay node is used for energy and information transfer. Large
intervals of information transfer implies little time for energy harvesting
from RF signals and thus, high probability of outage events. We propose relay
selection schemes for a cooperative system with a fixed number of RF powered
relays. We address both causal and non-causal channel state information cases
at the relay--destination link and evaluate the trade-off associated with
information/power transfer in the context of minimization of outage
probability.Comment: IEEE GlobalSiP, 201
Enabling non-linear energy harvesting in power domain based multiple access in relaying networks: Outage and ergodic capacity performance analysis
The Power Domain-based Multiple Access (PDMA) scheme is considered as one kind of Non-Orthogonal Multiple Access (NOMA) in green communications and can support energy-limited devices by employing wireless power transfer. Such a technique is known as a lifetime-expanding solution for operations in future access policy, especially in the deployment of power-constrained relays for a three-node dual-hop system. In particular, PDMA and energy harvesting are considered as two communication concepts, which are jointly investigated in this paper. However, the dual-hop relaying network system is a popular model assuming an ideal linear energy harvesting circuit, as in recent works, while the practical system situation motivates us to concentrate on another protocol, namely non-linear energy harvesting. As important results, a closed-form formula of outage probability and ergodic capacity is studied under a practical non-linear energy harvesting model. To explore the optimal system performance in terms of outage probability and ergodic capacity, several main parameters including the energy harvesting coefficients, position allocation of each node, power allocation factors, and transmit signal-to-noise ratio (SNR) are jointly considered. To provide insights into the performance, the approximate expressions for the ergodic capacity are given. By matching analytical and Monte Carlo simulations, the correctness of this framework can be examined. With the observation of the simulation results, the figures also show that the performance of energy harvesting-aware PDMA systems under the proposed model can satisfy the requirements in real PDMA applications.Web of Science87art. no. 81
Joint energy harvesting time allocation and beamforming in two-way relaying network
Abstract. A two-way relaying system with amplify-and-forward technique, where relay stations (RSs) acquire the energy from transmission signal and interferences, is considered. The RSs use the energy to amplify the signal received from the transmitter and forward it to the receiver. Particularly, energy harvesting (EH) and time switching (TS) are deployed. Based on the TS architecture, we divide transmission time into two time slots, which are EH phase and information transmission (IT) phase. In the EH phase, the RSs harvest the energy from the received radio frequency (RF) signal. In the IT phase, the RSs process and forward the transmission signal to the destination by energy harvesting during the EH phase. From such a transmission scheme, we investigate the optimal time ratio of the EH and IT phase as well as the beamforming at RSs in order to acquire the sum rate maximization. Since the sum-rate maximization problem is nonconvex, we develop an iterative algorithm based on the majorization-minimization (MM) technique to solve the problem. Furthermore, we deployed two schemes to overcome the self-interference to see the efficiency of each scheme related to sum-rate performance. The results show that power transmission and a number of relay station have a major impact on the sum rate performance of the two-way relay system
Outage performance analysis of cell-center/edge users under two policies of energy harvesting
In this paper, two energy harvesting policies deploying in cooperative non-orthogonal multiple access (NOMA) systems are considered. After period of wireless power transfer, the NOMA users including cell-edge and cell-center users simultaneously transmit the superposition coded symbols to the base station (BS). In the last time slot, the BS decodes to achieve its signal based on superposition coded symbol with corresponding power allocation factors. This paper provides exact expressions of outage probability in two schemes. Performance gap of two NOMA users can be raised by providing different power allocation factors. It is confirmed by numerical result. Distance and data rate are main factors affecting outage performance. Scheme I exhibit scenario where power beacon transmits energy signal to NOMA user while the BS feeds energy to NOMA user in Scheme II. It is shown that outage performance of Scheme I is better than that of Scheme II.Web of Science254807
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