r side were less than the quantity of receiver antennas. The proposed linear beamforming tech- nique highlighted that the capacity gain performance is significantly improved when 5G Wireless Communication System in Healthcare Informatics compared with the MIMO-OMA counterpart. Finally, a comprehensive NOMA survey is offered in [16]. 5.4 THE SYSTEM MODEL AND RESULTS This part will be used to introduce the PD-NOMA, CD-NOMA, and the realistic transmission of a PD-NOMA, alongside with their corresponding results. 5.4.1 POWER-DOMAIN NOMA The schematic of the overall PD-NOMA scheme is shown in Figure 5.2. The two users' signals, namely near user and far user will first be superimposed before the transmission. Below, each of the Figure 5.2 blocks will be explained further. 5.4.1.1 Superposition Modulation (SPM) Superposition modulation (SPM) is a widely known technique for non-orthogonal schemes. The concept of superposition modulation was introduced first in [17], the SPM joins two messages and transmits them simultaneously by encoding them in one signal. A signaling scheme is characterized by a constellation and a mapping rule. These two concepts are used in SPM. The SPM constellation for joining two users in a single signal is shown in Figure 5.3. At the transmitter side, the transmitted signals for the two users are superimposed using superposition coding (SC) as shown in Figure 5.4. For example, the QPSK modulated signals S and S2 2 will be linearly combined to generate a 16-QAM X SPM using SPM as follows: (5.1) where r and r2 are scaling factors to protect the signals, where a signal with higher scaling factor will be more protected with the condition that 1. 5.4.1.2 Successive Interference Cancellation (SIC) A typical MIMO system can be described by: y=Hx+n (5.2) Transmission Decoding Near User Message Direct Decoding Far User Message FIGURE 5.2 Power-Domain NOMA schematic diagram. Non-Orthogonal Multiple Access Transmission FIGURE 5.3 Constellation diagram explaining superposition coding for NOMA system. Messege