# Guaranteeing QoS for NOMA-Enabled URLLC Based on \(\kappa\)-\(\mu\) Shadowed Fading Model
## 4 Simulation Results and Analyses
The EE\({}_{\text{dB}}\) of the user under Nakagami-\(m\) fading (\(\kappa\to 0\), \(\mu=3\), \(m\rightarrow\infty\)) for controlling the transmit power to meet the UB-QDVP requirement (\(10^{-7}\)) is improved by 16.6% in EE\({}_{\text{dB}}\) over that of users under Rician shadowed fading (\(\kappa=4\), \(\mu=1,m=3\)) with the same UB-QDVP. Therefore, for delay-sensitive applications, performance analyses for indicators such as delay and reliability, power control and system design, the impacts of different small-scale fading characteristics on the performance of communication systems need to be considered. The accurate characterization of small-scale fading using the \(\kappa-\mu\) shadowed fading model may become a necessity for future wireless communication performance analysis and system design. Figure 6: Comparison of the UB-QDVPs in the CF mMIMO, PD-NOMA and OMA systems. (**a**) Comparison of different communication systems under One-sided Gaussian fading; (**b**) Comparison of different communication systems under Nakagami-\(m\) fading. Figure 7b-d compare the EE\({}_{\rm dB}\) and UB-QDVP values obtained under different distances from the user to the center of the coverage area (200 m or 1000 m) in three communications systems under Rician shadowed fading (\(\kappa=4,\mu=1,m=3\)), Rayleigh fading (\(\kappa\to 0,\mu=1,m\rightarrow\infty\)) and \(\kappa\)-\(\mu\) shadowed fading (\(\kappa=3,\mu=3,m=4\)) when the transmit power is 10 dBm, respectively. These three communication systems are the proposed CF mMIMO system, PD-NOMA and OMA systems equipped with 200 antennas in their base station. In Figure 7b, we can see that when the target delay is 0.1 ms and the distance to the center of the coverage area is 200 m, the user achieves \(\varepsilon_{k}^{v,{\rm UB}}\)=\(10^{-7}\) with EE\({}_{\rm dB}<40\) bit/J in the OMA system. Under the same conditions, the user in the PD-NOMA system can arrive at the same UB-QDVP with EE\({}_{\rm dB}>40\) bit/J, which is an EE\({}_{\rm dB}\) improvement of 5.1% over that of the OMA system. Furthermore, the user in the CF mMIMO system achieves a 2.4% increment in EE\({}_{\rm dB}\) compared with that of the PD-NOMA system. When EE\({}_{\rm dB}=27.65\) bit/J, the target delay is 0.1 ms and the distance to the center of the coverage area expands to 1000 m, the UB-QDVPs of the user in both PD-NOMA and OMA systems are greater than \(10^{-7}\). However, the UB-QDVP of the user in the CF mMIMO system is less than \(10^{-7}\) and is 97.5% lower than that of the PD-NOMA system. In Figure 7c, when the target delay is 0.1 ms and the distance to the center of the coverage area is 200 m, the user achieves \(\varepsilon_{k}^{v,{\rm UB}}\)=\(10^{-7}\) with EE\({}_{\rm dB}<40\) bit/J in the OMA system. Under the same conditions, the user  
Figure 7: The UB-QDVP vs. EE\({}_{\rm dB}\) under the \(\kappa\)–\(\mu\) shadowed fading model. (**a**) Comparison of different small-scale fading types; (**b**) Comparison of different communication systems under Rician shadowed fading; (**c**) Comparison of different communication systems under Rayleigh fading. (**d**) Comparison of different communication systems under \(\kappa\)–\(\mu\) shadowed fading. in the PD-NOMA system can arrive at the same UB-QDVP with \(\text{EE}_{\text{dB}}=40\) bit/J, which is an \(\text{EE}_{\text{dB}}\) improvement of 11.1% over that of the OMA system. Furthermore, the user in the CF mMIMO system achieves a 13.9% increment in \(\text{EE}_{\text{dB}}\) compared with that of the OMA system. When \(\text{EE}_{\text{dB}}=27.65\) bit/J, the target delay is 0.1 ms and the distance to the center of the coverage area expands to 1000 m, the UB-QDVPs of the user in both PD-NOMA and OMA systems are greater than \(10^{-7}\). However, the UB-QDVP of the user in the CF mMIMO system is less than \(10^{-7}\) and is 99.4% lower than that of the PD-NOMA system.