Received: 1 July 2018 Revised: 23 September 2018 Accepted: 20 November 2018
Cooperative non-orthogonal multiple access with SWIPT
over Nakagami-mfading channels
Md. Fazlul Kader1Mohammed Belal Uddin2Anik Islam2Soo Young Shin2
1Department of Electrical and Electronic
Engineering, University of Chittagong,
2Department of IT Convergence
Engineering, Kumoh National Institute of
Technology, Gumi, South Korea
Md. Fazlul Kader, Department of
Electrical and Electronic Engineering,
University of Chittagong,
Chittagong 4331, Bangladesh.
University of Chittagong, Bangladesh;
MSIT (Ministry of Science, ICT), Korea,
To meet with both the energy and spectral efficiency, cooperative
non-orthogonal multiple access (NOMA) (termed as CNOMA) and simul-
taneous wireless information and power transfer (SWIPT) are integrated
in this paper. Two different protocols such as CNOMA-SWIPT-PS and
CNOMA-SWIPT-TS are proposed, by employing power-splitting (PS) and
time-switching (TS) energy harvesting (EH) techniques, respectively. In the pro-
posed protocols, a base station (BS) directly communicates with a NOMA near
user, whereas the communication with a NOMA far user is performed with the
assistance of an energy-constrained relay node. The relay node harvests energy
from the transmitted signal by the BS, employing PS or TS EH technique. We
investigate ergodic sum capacity and outage probability of the proposed pro-
tocols along with analytical derivations over Nakagami-mfading channels.
Finally, the effectiveness of the proposed schemes over existing strategy and
conventional multiple access is demonstrated through analysis and simulation.
To cope with the anticipated challenges of the future wireless networks, fifth-generation wireless systems, abbreviated
5G, are expected to be emerged by 2020.1,2Among the various challenging requirements of 5G, spectral efficiency and
energy efficiency are the two key requirements. To deal with both of these requirements, non-orthogonal multiple access
(NOMA) and simultaneous wireless information and power transfer (SWIPT) can be integrated, which is the main focus
of this paper.
NOMA is an exciting and emerging multiple access technique, which is viewed as one of the key players in 5G, because
of its manifold spectral gains.3-5In a NOMA-based system, multiple signals are superimposed in power domain at the
transmitter side, by the same code at the same frequency, which is unlike the conventional multiple access (orthogonal
multiple access [OMA]) schemes (eg, frequency/time/code division multiple access). At the receiver side, signal decoding
technique such as successive interference cancelation (SIC) can be carried out to decode each signal.6NOMA can be
applied in a wide range of application scenarios. Among them, cooperative NOMA is one of the most active areas of
research. Cooperative NOMA can be broadly categorized into two different types.7In the first type, NOMA-strong users
act as relays to the NOMA-weak users.8On the contrary, dedicated relays are used to assist the NOMA users,9-13 in the
second type. In general, users residing close to the base station (BS) are called strong or near users, whereas users residing
close to the cell edge are called weak or far users.
Because of the vast amount of coexisting wireless technologies, radio frequency (RF) signals are abundant in nature.
These RF signals can be exploited to harvest energy for powering up the energy-constrained nodes.14,15 To prolong the
Trans Emerging Tel Tech. 2019;30:e3571. wileyonlinelibrary.com/journal/ett © 2019 John Wiley & Sons, Ltd. 1of16