(4.51) Otherwise, the outage probability will be always in the high SNR regime. 4.2.3.4 Diversity Analysis for UE 2 Based on the definition of diversity, we have (4.52) This means in the non-linear energy harvest model, no diversity will be achieved. The rea- son is that as the input power increases, the power harvested becomes saturated, which limits the further data rate growth, hence the outage probability performance. 4.2.4 Numerical Results In this section, numerical performance results are presented based on both simulations and analysis. The parameters for evaluation are chosen in the following. a0 = 4, which indicates the horn antenna gain is 6 dB. A1 = 0.4, 22 = 0.6. M = 4, which means the maximum charg- ing power for the relay is 4 Watts. For illustration purposes, the distance dBR, RR2, and d are small, which are set to 8, 2, and 10, respectively. Similar settings can also be found in [108]. Furthermore, the predefined thresholds for data rates are R1 = R3 = 0.5 bps/Hz and R2 = 0.3 bps/Hz. Figure 4.8 shows the outage probability of UE 1 and UE 2 with regards of the transmission SNR in dB. "ana" stands for analytical result while "sim" is the simulation one. The perfor- mance can be optimized by carefully choosing X1 and N2. The detailed study on how to select A1 and a values to achieve optimal performance is not the focus of this chapter and hence not extended. Further, since a and b can also impact the system performance, the outage probability of UE 2 is evaluated with different a, b values. By fixing B = 0.8, both the sim- ulation and analytical results are presented. As we can see from Figure 4.8, the analytical results match well with the simulation ones for UE 1. As expected, the outage probabil- ity decreases linearly in log scale with the increase of transmission SNR. For UE 2, when a = 2.5, b = 3, the outage probability of UE 2 is lower than the case with a = 6.5, b = 4, which indicates that energy harvest circuit will affect the system performance. Also, as the 4 NOMA in Relay and loT for 5G 