igure 4.7 Power-in-power-out response in the non-linear energy harvest model. is saturated. a together with b capture the joint effect of resistance, capacitance, and circuit sensitivity [19]. Boshkovska et al. [21] provides a more sophisticated model, which captures the zero-input-zero-out feature in wireless charging and can be modeled in the following. (4.36) where In the subsequent analysis, we use model (4.35) based on the following reasons. (i) Our model does not have zero-power input case; (ii) The general logistic function can reduce the complexity in outage analysis; (iii) (4.35) can provide sufficient precision. Figure 4.7 presents the power-in-power-out relation with 1000 independent events, based on which the parameters are estimated as follows, B = 0.6, o = 0.0995, M = 10, a 1, b = BPBRO2, and PBR=30 dB. 4.2.2.2 Phase 2 Transmission During the second phase, the relay sends X2 to UE 2 with the energy harvested in Phase 1. Meanwhile, the BS sends another signal X3 to UE 1. The received signal at UE 1 and UE 2 is expressed as (4.37) (4.38) respectively. 4.2 NOMA in a mmWave-Based loT Wireless System with SWIPT Since UE 1 already decodes X2 in Phase 1, by appropriately estimating the channel hR1, it can employ SIC to subtract X2 from its observation [96]. The remaining SINR becomes (4.39) For UE 2, since there is a severe blockage between BS and itself, it has a negligible interfer- ence from BS. The achievable SINR at UE 2 is (4.40) 4.2.3 Outage Analysis In this section, we will provide mathematical analysis on the outage probability of the pro- posed scheme. The outage probability is defined as the probability of events where certain measurements such as SINR or data rate cannot meet the pre-defined threshold. 4.2.3.1 UE 1 Outage Probability Define the minimum data rates for messages X1,X2, and X3 as R1, R2, and R3, respectively. Below the minimum data rate, a UE will have an outage. Since UE 1 involves in both phases, outage occurs when UE 1 fails to decode X2 and X1 in phase 1 or fails to decode X3 i