by academic researchers and networking providers. The pioneering studies examined outage probability, system throughput, ergodic capacity, and secrecy performance. The achieved results proved that the NOMA technique showed a system performance which outperformed the orthogonal multiple access (OMA) technique. NOMA system served multiple IoT devices by a single radio frequency (RF) transmission block [1; 2; 3]. The NOMA-IoT network employed superposition coding technique at the transmitter to encode the superimposed signals of multiple IoT devices over the same RF transmission block by allocating power multiplexing [4]. The initial signals of different IoT devices over the same RF transmission block at the base station (BS) are separated by allocating different power levels. Allocated power levels are based on the channel state information (CSI) of IoT devices [5]. The BS transmits the superimposed signal to those IoT devices with better CSI at lower transmitting power level. On the contrary, BS allocated high power level to transmit IoT device's data with poorer CSI [6]. IoT devices employ successive interference cancellation (SIC) mechanism to decode their own message contained in the superimposed signal. The IoT device decodes the message with strongest power allocation (PA) factor by treating the other messages with lower PA factors and additive white Gaussian noise (AWGN) as interference. The IoT device then repeats SIC until detecting it own message successfully. In the study by [7], the author examined a dual-hop cooperative network with a multi-branch using all participate relay. Overall, relay selection (RS) strategies are in two categories, i.e., single RS and multi-RS as shown in [8; 9; 10; 11; 12; 13]. For clarity, the authors selected relay based on error rate and energy efficiency ratio [11] or signal to noise ratio (SNR) maximization [13]. The incremental relay led to the achievement of higher spectral efficiency; however, higher hardware cost and complexity [14]. Therefore, this study employed a coupled relay as in [15] which shared its benefits with the multi-relay scheme; however, there was a light incremental hardware cost. This study selects just one relay for forwarding signals, by adopting the decode-and-forward (DF) protocol. Although there have been significant improvements in the benefits of spectral sharing efficiency, the study of the energy efficiency of NOMA-IoT networks is still at the initial stage. Furthermore, simultaneous wireless information and power transfer (SWIPT) the utility of RF to transfer wireless information and energy to the receiver simultaneously has been shown in many studies. Integration of the SWIPT technique in the NOMA system has been studied from the perspective of outage probability (OP) and energy harvesting (EH) performance [15; 16; 17; 18]. Unfortunately, due to the utility functions of RF signal and broadcast superimposed signal of NOMA system, the wireless signal propagation from transmitter to receiver may be eavesdropped on by an illegitimate device. More specially, physical layer security (PLS) is another crucial challenge to protect legitimate devices from a potential eavesdropper in IoT wireless networks. In [3], the EH at receivers may intercept the threat to secure data propagated between legitimate IoT devices. To improve secrecy performance to the low-powered IoT devices, PLS was introduced as an alternative to the ultra-high complex cryptography algorithm [19]. PLS strategies may enhance the secrecy performance of IoT wireless networks by cooperative IoT relaying [18; 20], multi-antenna beamforming [14; 21; 22; 23; 24; 25], and jamming signal [26; 27; 28; 29; 30; 31; 32; 33]. There is a gap for cooperative wireless communication networks to achieve distributed spatial diversity, wider networking coverage, lower energy consumption, and reduced interference [14; 22]. Cooperative wireless communication networks were significantly improved by the benefit of RS protocol.