Impact of fixed power allocation in wireless energy harvesting NOMA networks

Received: 29 May 2018 Revised: 23 April 2019 Accepted: 23 April 2019

DOI: 10.1002/dac.4016

RESEARCH ARTICLE

Impact of fixed power allocation in wireless energy

harvesting NOMA networks

Dinh-Thuan Do1 Chi-Bao Le2

1Wireless Communications Research

Group, Faculty of Electrical and

Electronics Engineering, Ton Duc Thang

University, Ho Chi Minh City, Vietnam

2Faculty of Electronics Technology,

Industrial University of Ho Chi Minh City

(IUH), Ho Chi Minh City, Vietnam

Correspondence

Dinh-Thuan Do, Wireless

Communications Research Group, Faculty

of Electrical and Electronics Engineering,

Ton Duc Thang University, Ho Chi Minh

City, Vietnam.

Email: [email protected]

Summary

The time switching-based relaying (TSR) scheme is considered in energy

harvesting protocol to implement with its advantage to nonorthogonal multiple

access (NOMA) system. In particular, decode-and-forward (DF) mode is pro￾posed to employ in relay to forward signal to serve two far NOMA users. There

are two main metrics including outage probability and ergodic rate, which are

derived in exact expressions with respect to varying performance under impacts

of energy harvesting fractions. To evaluate system performance, outage event

and related capacity are illustrated, and we tailor performance gap among two

NOMA users and such gap can be controlled by selecting of appropriate power

allocation factors assigned for each user to obtain optimal performance. By

examining node arrangement, target rates and varying transmit signal to noise

ratio (SNR), it can be further achieved performance in several situations of

such NOMA. As important result, the considered NOMA system outperforms

than the conventional multiple access scheme, and this expected result is con￾firmed in numerical result and theoretical results. We also explore impacts of

transmit power at source, noise power, the other key parameters of energy har￾vesting scheme to exhibit outage, and ergodic performance. Simulation results

are presented to corroborate the proposed methodology.

KEYWORDS

decode and forward, energy harvesting, non-orthogonal multiple access, outage probability

1 INTRODUCTION

Current trends need be addressed in development of wireless communication such as the rapid growth of services,

massive connections, the demand for increasing power consumption in operation of small devices in Internet of

Things (IoT) deployment. Such requirements in wireless terminals result in energy shortage and advantages of vari￾ous energy harvesting (EH) architectures introduced green communication solution. In particular, relaying network has

now been recommended to improve the overall system energy efficiency by exploiting information-transmission and

energy-transmission cooperation. In EH technique, solar and wind are considered as popular energy resources that are

intermittent under impacts the environmental alteration. More specifically, radio frequency (RF) signal is considered as a

new viable source, which can be applied in wireless power transfer (WPT).1 Nevertheless, regarding traditional relay nodes

using batteries to power and hence such mobile devices meet limited performance due to the short battery lifespan. In the

previous studies,2-6 the authors have put forward EH protocol in relaying networks. For instance, assuming a stationary

and ergodic process in terms of energy scavenged by the relay, by taking energy-constrained and energy-unconstrained

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https://doi.org/10.1002/dac.4016