# An Optimized Planning Tool for Microwave Terrestrial and Satellite Link Design
## 4 Use Case
### Terrestrial Project  
This subsection presents the design of a terrestrial RF communication project between a station located in Moscavide (Lisbon, Portugal) and a station located in Palmela (Setubal, Portugal), using the characteristics shown in Table 2. \begin{table}
\begin{tabular}{c c} \hline \hline Frequencies (GHz) & \(1,3,5,7,9\) \\ \hline Antennas radiation efficiency (\%) & 50 \\ \hline Transmission power (W) & 20 \\ \hline Transmission rate (Mbits/s) & 140 \\ \hline Bandwidth (MHz) & 34 \\ \hline Roll of factor & 0.142 \\ \hline Modulation & 64-QAM \\ \hline Polarization & Horizontal \\ \hline Residual BER (RBER) & \(1\times 10^{-12}\) \\ \hline Quality of service (QoS) & X = 0.08 \\ \hline Additional attenuations (dB) & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Simulated terrestrial link characteristics. Figure 11: Satellite project link budget step window. Based on the outputted results, the signal reflection was no longer a degrading element to the system. To establish a reliable communication system, the system should verify all defined margins, in addition to having a system critical margin above 3 dB [12]. For the simulated project, the verification of project clauses is presented in Table 5.  
Based on the clause analysis, the critical margins for these clauses were calculated, which are presented in Table 6.  
As presented in both Tables 5 and 6, all clauses were fulfilled only when a frequency of 5 GHz was used. Conversely, using this system frequency did not fulfill a project critical margin of 3 dB (having a 1.2 dB project critical margin), as previously mentioned. Subsequently, diversity and signal equalization was used. The introduction of diversity and equalization led to the requirement to obtain a 3 dB threshold for the project's critical margin. For this system, both methods of diversity were implemented, as well as signal equalization. These methods were implemented using the characteristics shown in Table 7.  
As a result of diversity and equalization implementations, the project's critical margins were recalculated, and the obtained values are presented in Table 8.  
Using this method, the project's critical margin with 5 GHz communication frequency was increased to 4.0 dB, thus creating a reliable communication system using the elements and characteristics described throughout the design of the project. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Frequency (GHz)** & **1** & **3** & **5** & **7** & **9** \\ \hline SESR critical margin (dB) & \(-11.96\) & \(1.7\) & \(5.6\) & \(0.7\) & \(-10.6\) \\ \hline BBER critical margin (dB) & \(-16.3\) & \(-2.6\) & \(1.2\) & \(-3.6\) & \(-14.9\) \\ \hline ESR critical margin (dB) & \(4.2\) & \(15.6\) & \(17.2\) & \(15.0\) & \(5.5\) \\ \hline Unavailability due to rain critical margin (dB) & \(1.3\) & \(19.5\) & \(23.7\) & \(13.6\) & \(-7.4\) \\ \hline Project critical margin (dB) & \(-16.3\) & \(-2.6\) & \(1.2\) & \(-3.6\) & \(-14.9\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The critical margins of project clauses for the simulated terrestrial project. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Frequency (GHz)** & **1** & **3** & **5** & **7** & **9** \\ \hline Free-space attenuation (dB) & 230.7 & 249.8 & 258.7 & 264.5 & 268.9 \\ \hline Obstacles attenuation (dB) & 0 & 0 & 0 & 0 & 0 \\ \hline Atmospheric attenuation (dB) & 0.1 & 0.3 & 0.5 & 0.8 & 1.2671 \\ \hline Rain attenuation (dB) & 0.03 & 0.4 & 2.7 & 11.4 & 25.3 \\ \hline Signal reflections (dB) & \(-\infty\) & \(-\infty\) & \(-\infty\) & \(-\infty\) & \(-\infty\) \\ \hline SNR in IPC (dB) & 26.8 & 45.3 & 51.3 & 47.98 & 37.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: System elements with passive repeater addition for the simulated terrestrial project.