# Evaluation of 5G Positioning Based on Uplink SRS and Downlink PRS Under LOS and NLOS Environments
## 3 Simulation Results
\begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Comb Size**} & \multicolumn{2}{c}{**UL-SRS**} & \multicolumn{2}{c}{**DL-PRS**} \\ \cline{2-5}  & **LOS [m]** & **NLOS [m]** & **LOS [m]** & **NLOS [m]** \\ \hline
2 & 2.44 & 9.62 & 2.25 & 11.64 \\ \hline
4 & 2.91 & 10.12 & 2.86 & 12.14 \\ \hline
6 & — & — & 3.49 & 13.20 \\ \hline
8 & 3.60 & 10.37 & — & — \\ \hline \end{tabular}
\end{table} 
Table 4: Positioning error at BS–BS distance of 150 m.  
Figure 12: Positioning accuracy of UL-SRS and DL-PRS. Figure 13a demonstrates the positioning performance of 5G in a LOS scenario. In this case, the observed positioning error is 2.06 m, indicating a high level of accuracy due to the direct propagation of the signal between the gNBs and the UE, with minimal interference. As the comb size increases from 2 to 8, the positioning error also rises from 2.06 to 3.41 m. This reflects the trade-off between comb size and time resolution, where larger comb sizes reduce time resolution and thus degrade accuracy. Conversely, Figure 13b depicts the same environment under an NLOS condition, where the lack of a direct signal path leads to an increased positioning error of 8.48 m. In this scenario, the signal encounters multiple reflections, causing distortion of its trajectory and an associated delay in its arrival at the receiver. Furthermore, with increasing comb size from 2 to 8, the NLOS positioning error increases from 8.48 to 9.20 m. The consistent performance of the SRS under challenging propagation conditions highlights its effectiveness for precise 5G positioning. Figure 14 illustrates the performance of DL-PRS-based positioning in both LOS and NLOS scenarios. The estimated and actual UE positions relative to gNBs are displayed, with the impact of comb size on localization accuracy. The positioning accuracy varies depending on the comb size, influencing the trade-off between spectral efficiency and time delay resolution. A lower comb size, particularly comb-2, provides high-accuracy positioning by providing better time delay resolution and improved TOA estimation. This approach enables precise localization, even in challenging environments. As illustrated in Figure 14a, PRS positioning in the LOS scenario demonstrated a high degree of precision, with a minimal deviation of 1.94 m between the actual and estimated UE positions. However, as the comb size increases from 2 to 6, the positioning error in LOS conditions also rises from 1.94 to 3.09 m. This accuracy is attributed to the direct propagation of PRS signals, ensuring reliable TOA measurements. The well-defined intersection point of TOA circles further reinforces the precision of PRS-based localization under LOS conditions. In contrast, Figure 14b presents the NLOS scenario, where PRS accuracy degrades significantly due to the presence of obstacles and obstructions. The positioning error increases to 10.47 m, primarily due to signal reflections and additional propagation delays. Similarly, the NLOS positioning error increases with larger comb sizes, rising from 10.47 m at comb-2 to 11.30 m at comb-6, highlighting the greater challenge of maintaining accuracy in obstructed environments. Figure 13: UE position through UL-SRS under: (**a**) LOS; (**b**) NLOS.