Preprint Article Version 1 This version is not peer-reviewed

# Multi-Points Cooperative Relay in NOMA System with N-1 DF Relaying Nodes in HD/FD mode for N User Equipments with Energy Harvesting

Version 1 : Received: 9 December 2018 / Approved: 10 December 2018 / Online: 10 December 2018 (15:18:44 CET)

A peer-reviewed article of this Preprint also exists.

Tran, T.-N.; Voznak, M. Multi-Points Cooperative Relay in NOMA System with N-1 DF Relaying Nodes in HD/FD Mode for N User Equipments with Energy Harvesting. Electronics 2019, 8, 167. Tran, T.-N.; Voznak, M. Multi-Points Cooperative Relay in NOMA System with N-1 DF Relaying Nodes in HD/FD Mode for N User Equipments with Energy Harvesting. Electronics 2019, 8, 167.

Journal reference: Electronics 2019, 8, 167
DOI: 10.3390/electronics8020167

## Abstract

Non-Orthogonal Multiple Access (NOMA) is the key technology promised to be applied in next-generation networks in the near future. In this study, we propose a multi-points cooperative relaying (MPCR) NOMA model instead of just using a relay as the previous studies. Based on the channel state information (CSI), the base station (BS) selects a closest user equipment (UE) and sends a superposed signal to this UE as a first relay node. We have assumed that there are N UEs in the network and Nth UE, which is farthest from BS, has the poorest quality signal transmitted from the BS compared other UEs. Nth UE received the forwarded signal from N-1 relaying nodes that are UEs with better signal quality. At the ith relaying node, it detect its own symbol by using successive interference cancellation (SIC) and will forward the composite signal to the next closest user, namely i+1th UE, and include an excess power which will use for energy harvesting (EH) intention at the next UE. By these, the farthest UE in network can be significantly improved. In addition, closed-form expressions of outage probability for users over both the Rayleigh and Nakagami-m fading channels are also presented. Analysis and simulation results performed by Matlab software which are presented accurately and clearly show that the effectiveness of our proposed model and this model consistents with the multi-access wireless network in future.

## Subject Areas

Cooperative NOMA; multi-points DF relaying nodes; half-duplex; full-duplex; Rayleigh fading channels; Nakagami-$m$ fading channels; energy harvesting

Comment 1
Received: 5 January 2019
Commenter: Mohamed Mounir (Click to see Publons profile: )
The commenter has declared there is no conflict of interests.
Comment: Authors have to explain how Allocation power coefficients in Table 1 and 2 are chosen.
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Response 1 to Comment 1
Received: 6 January 2019
Commenter: Nam Tran
The commenter has declared there is no conflict of interests.
Comment: Dear Dr. Mohamed Mounir,
About Allocation power coefficients in Table 1 and 2, they are allocated by (42) in this article. E.g., "There have some s
simulation parameters, e.g., the channel coefficients h0,1 = 1, h0,2 = 1/2, and h0,3 = 1/3 are in accordance with the earlier presented assumptions. Based on the transmission channel coefficients of the users, we can allocate power factors for users UE1, UE2, and UE3 with a1 = 0.1818, a2 = 0.2727, a3 = 0.5455, respectively, with ∑ai = 1 by applying (42), where i ={1,3}."
Because U1, U2, U3 channels have been reduced in list. E.g., a1 = (1/3)/(1+1/2+1/3)=0.1818.
I'm sorry if my English is not clear. Please continue to review this study and let me know any of your comments.
Thanks you and best regards,
Thanh-Nam Tran

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