## 6 NR Tracking Performance Analysis for Different NR and Receiver Configuration
### Impact of Receiver Configuration on Tracking Accuracy  
DLL tracking accuracy is also determined by NR receiver configurations: (1) coherent integration time (\(T_{\text{coh}}\)), (2) DLL loop bandwidth (\(B_{L}\)), and (3) different local replica signals. \(T_{\text{coh}}\) determines the integration duration of the integrate-and-dump filter, while the loop bandwidth \(B_{L}\) governs both DLL tracking accuracy and dynamic response speed. Figure 11 and Table 2 demonstrate DLL tracking accuracy with different coherent integration time \(T_{\text{coh}}\) and DLL bandwidth \(B_{L}\), and the results reveal that (1) at 60 dBm transmitting power with fixed \(B_{L}=20\) Hz, decreasing \(T_{\text{coh}}\) to 5 ms (relative to the baseline \(T_{\text{coh}}=10\) ms, \(B_{L}=20\) Hz) reduces DLL tracking accuracy by 2.52%, while elevating \(T_{\text{coh}}\) to 15 ms enhances accuracy by 2.52%; and (2) at 60 dBm with fixed \(T_{\text{coh}}=10\) ms, reducing \(B_{L}\) from 20 Hz (baseline) to 5 Hz and 1 Hz yields DLL tracking accuracy improvements of 48.10% and 76.58% respectively, indicating the stronger influence of loop bandwidth on DLL tracking accuracy. Generally, extending \(T_{\text{coh}}\) or reducing \(B_{L}\) enhances DLL tracking accuracy.  
Figure 10: Relationship between portion of NR reference signal and tracking accuracy.  
Multiple reference signals, such as SSB, CSI-RS, and DMRS in PDCCH and PDSCH, can be used as local replica signals for an NR navigation receiver. The selection of local replica signals significantly influences DLL tracking accuracy. Previous experiments only utilize PDSCH DMRS as the local replica signal. This experiment systematically evaluates the impact of four NR replica signals: (1) SSB only; (2) PDSCH DMRS only; (3) combined PDSCH DMRS and SSB; and (4) combined PDSCH DMRS, SSB, and CSI-RS. The DLL tracking accuracy with different replica signals is plotted in Figure 12, and the proportion of the replica reference signal is listed in Table 3. The results show the following: First, exclusive use of PDSCH DMRS yields inferior tracking accuracy compared to other configurations; and second, composite replica signals demonstrate measurable improvements in tracking accuracy. At 60 dBm transmitting power, the combined PDSCH DMRS+SSB achieves a 3.48% accuracy enhancement over SSB only, while the full combination (PDSCH DMRS+SSB+CSI-RS) provides a 5.06% improvement. The proportion of CSI-RS and PDSCH DMRS is lower than 4%, so the improvement in tracking accuracy is not apparent. This enhancement in tracking accuracy is attributed to the increased correlator output power achieved through reference signal superposition. Hence, all predictable NR signals should be used as reference signals to improve navigation performance.  
In summary, this section analyzes the impact of NR signal and receiver configurations on DLL tracking accuracy, offering systematic insights for LEO OFDM navigation design. Based on the tracking results, the positioning performance is discussed in the following.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **PBCH** & **CSI** & **PDSCH DMRS** & **PDSCH Data** & **Sum** \\ \hline Resource Elements & 830 & 80 & 200 & 4600 & 5710 \\ Resource Proportion (Power Proportion) & 14.54\% & 1.40\% & 3.50\% & 80.56\% & 100.00\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: Resource elements distribution in an NR frame.  
Figure 11: DLL tracking accuracy with different coherent integration time \(T_{\text{coh}}\) and DLL loop bandwidth \(B_{L}\).