# Guaranteeing QoS for NOMA-Enabled URLLC Based on \(\kappa\)-\(\mu\) Shadowed Fading Model
## 4 Simulation Results and Analyses
Otherwise, the final result or conclusion obtained will differ greatly from reality, eventually leading to analysis results with less practical value and significance. Figure 6a compares the UB-QDVPs obtained under different distances from the user to the center of coverage area (200 m or 1000 m) in three communication systems under One-sided Gaussian fading (\(\kappa\to 0,\mu=0.5,m\rightarrow\infty\)) when the transmit power is 10 dBm. These three communication systems are the CF mMIMO system we proposed, PD-NOMA and OMA systems equipped with 200 antennas in their base station. We observe that the UB-QDVP of the PD-NOMA system is lower than that of the OMA system, and the UB-QDVP of the CF mMIMO system is lower than that of the PD-NOMA system under the same target delay when the distance from the user to the center of the coverage area is 200 m. In detail, when the target delay is 0.06 ms and the distance from the user to the center of the coverage area is 200 m, the UB-QDVPs of the PD-NOMA and OMA systems exceed \(10^{-7}\), and only the UB-QDVP of the CF mMIMO system is lower than \(10^{-7}\). Under a target delay of 0.07 ms, the UB-QDVPs of the CF mMIMO system and the PD-NOMA  
Figure 5: Performance comparison conducted for the CF mMIMO system under the \(\kappa\)-\(\mu\) shadowed fading model. (**a**) Comparison between Rician and Rayleigh fading channel; (**b**) Comparison between Rayleigh and One-sided fading channel; (**c**) Comparison between One-sided and Nakagami-\(m\) fading channel; (**d**) Comparison between Nakagami-\(m\) and Rician shadowed fading channel; (**e**) Comparison between Rician shadowed and the \(\kappa\)-\(\mu\) shadowed fading channel; (**f**) Comparison between the \(\kappa\)-\(\mu\) shadowed and Rician fading channel. system are below \(10^{-7}\). However, under the same parameter settings, the UB-QDVP of the OMA system is still higher than \(10^{-7}\). Specifically, we extended the distance from the user to the center of the coverage area to 1000 m and set the target delay to 0.08 ms. Only the CF mMIMO system can achieve a UB-QDVP lower than \(10^{-7}\), and both the PD-NOMA and the OMA systems cannot. Figure 6b plots the UB-QDVP for a user at 200 m or 1000 m from the center of the coverage area under Nakagami-\(m\) fading (\(\kappa\to 0\), \(\mu=3\), \(m\rightarrow\infty\)) for the CF mMIMO system, PD-NOMA system, and OMA system when the transmit power is 10 dBm. It is also clear from Figure 6b that when the user is 200 m from the center of the coverage area, the UB-QDVP of the CF mMIMO system is lower than that of the PD-NOMA system, which in turn is lower than that of the OMA system, for the same target delay. For example, when the target delay is 0.06 ms, the UB-QDVP is lower than \(10^{-7}\) for the CF mMIMO system and PD-NOMA system, and higher than \(10^{-7}\) for the OMA system when the user is 200 m away from the center of the coverage area. When the user is 1000 m away from the center of the coverage area and the target delay is 0.07 ms, only the UB-QDVP of the CF mMIMO system is lower than \(10^{-7}\), and the UB-QDVPs of the PD-NOMA system and OMA system are higher than \(10^{-7}\). Figure 6a,b confirm that the CF mMIMO system not only optimizes the reliability and delay performance, but also expands the coverage area for providing URLLC services in comparison with the PD-NOMA and OMA systems. Figure 7a shows the relationship between EE\({}_{\text{dB}}\) and the UB-QDVP under different fading environments in the proposed CF mMIMO communication system when the transmit power is 10 dBm, the target delay is 0.08 ms and the distance from the user to the center of the coverage area is 200 m. As seen from Figure 7a, as the UB-QDVP becomes tighter, EE\({}_{\text{dB}}\) decreases. Under different fading environments, the EE\({}_{\text{dB}}\) of the user for the same UB-QDVP is different, and a gap is observed.