# Optimization of RIS-Assisted 6G NTN Architectures for High-Mobility UAV Communication Scenarios
## 4 Joint Optimization Framework for RIS Configuration and UAV Mobility
### Performance Evaluation and Trade-Off Analysis
#### 4.3.4 Latency
The following sections break down the trends observed for each metric. \begin{table}
\begin{tabular}{l l} \hline \hline
**Parameter** & **Value/Description** \\ \hline M\_values & Number of RIS elements (10 to 50) \\ \hline num\_trials & 1000 trials for statistical significance \\ \hline Carrier Frequency (\(f_{c}\)) & 2.4 GHz \\ \hline Speed of Light (\(c\)) & \(3\times 10^{8}\) m/s \\ \hline Transmit Power (\(P\)) & 1 W \\ \hline Noise Variance (\(\sigma^{2}\)) & \(1\times 10^{-3}\) W \\ \hline Bandwidth (\(B\)) & 10 MHz \\ \hline Power per RIS Element (\(P_{\text{RIS}}\)) & 0.1 W \\ \hline NTN Power (\(P_{\text{NTN}}\)) & 10 W \\ \hline Processing Time per Element (\(\tau_{\text{RIS}}\)) & 1 μs \\ \hline Transmission Delay (\(T_{\text{tx}}\)) & 1 ms \\ \hline Scenarios & Urban, rural, highway, indoor, emergency \\ \hline Scenario Variations & Different interference scales and shadowing standard deviations \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Scenario-specific parameters. Figure 3: Scenario-specific performance trade-offs in RIS-assisted NTNs: Signal-to-interference-plus-noise ratio (SINR), throughput, energy efficiency, outage probability, and latency as functions of RIS element count (M) in urban, rural, highway, indoor, and emergency high-mobility scenarios. #### 5.1.1 Signal-to-Interference-Plus-Noise Ratio (SINR) [dB]

**Trend:** The urban scenario starts with a relatively high SINR, which fluctuates slightly and then gradually declines as \(M\) increases. The highway scenario shows a steady improvement in SINR, indicating that more RIS elements benefit the signal quality in this environment. The rural scenario exhibits a consistent decline in SINR, which may be attributed to increased interference or unfavorable propagation conditions. The indoor scenario remains mostly stable with slight variations, showing little sensitivity to RIS element growth. The emergency scenario follows a decreasing trend, with its SINR starting relatively high but dropping over time, possibly due to interference effects in dynamic emergency conditions. **Interpretation:** Increasing the number of RIS elements \(M\) does not always lead to higher SINR in all environments. Although the highway scenario benefits from additional RIS elements due to relatively predictable signal propagation, other environments such as urban and rural environments experience limited improvements or declining SINR trends, likely due to interference and environmental obstacles. The emergency scenario, which starts with a high SINR, suggests an initial benefit from RIS deployment but suffers degradation at higher values of \(M\), potentially due to complex signal interactions in critical situations. The stability of the indoor scenario indicates that RIS elements have minimal impact in controlled environments where multipath effects dominate. This analysis highlights that the impact of the deployment of RIS is highly environment-dependent and simply increasing \(M\) may not always yield better signal quality. #### 5.1.2 Throughput [Mbps]

**Trend:** The urban scenario shows a steady but slow increase in throughput as \(M\) increases. The rural scenario initially remains stable but experiences a significant increase at higher \(M\), indicating that more RIS elements improve performance in this environment. The highway scenario starts with the highest throughput but slightly declines as \(M\) increases, suggesting that additional RIS elements may not be as beneficial due to possible interference or diminishing returns. The indoor scenario exhibits a gradual increase in throughput, while the emergency scenario declines slightly with more RIS elements, likely due to interference effects or environmental challenges. **Interpretation:** Increasing the number of RIS elements does not always lead to a uniform throughput improvement in all environments. While rural and indoor scenarios benefit from higher \(M\), highway and emergency conditions show signs of saturation or interference at higher RIS deployments.