# Optical Channel Selection Avoiding DIPP in DSB-RFoF Fronthaul Interface
## 3 Calculation Results
### Relative Delay and CP-OFDM Modulation  
The CP-OFDM modulation is applied to the 5G-NR downlink, which allows dynamic allocation of radio resources to different user equipment (UE) on the same frequency channel. The smallest unit consists of 12 OFDM subcarriers, and the frequency bandwidth of this resource is dependent on a numerological parameter that defines the frequency spacing between OFDM subcarriers [49; 50] (Table 8). As a result of combining all radio resource blocks, a frequency channel is created, which has a width of up to 400 MHz in 5G NR. Of course, the entire channel is not signal covered, as it requires frequency guard \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{_\(f_{RF}\) (GHz)_}} & \multicolumn{2}{c}{**Optical Subband (THz)**} \\ \cline{2-3} \cline{3-4}  & **3-dB** & **10-dB** \\ \hline
6 & 205.3380–184.4880 & 205.3380–184.4880 \\
12 & 205.3380–187.8630 & 205.3380–184.4880 \\
28 & 205.3380–200.5755; 189.2442–184.5630 & 205.3380–198.1880; 191.1068–184.4880 \({}^{1}\) \\  & 205.0192–203.3630; 200.3505–198.9067; & 205.3380–202.7880; 200.8880–198.3942; \\
60 & 196.2442–194.9630; 192.5630–191.3817; & 196.7255–194.5130 \({}^{1}\) ; 193.0067–190.9630; \\  & 189.1819–188.1130; 186.1130–185.1317 & 198.5981–187.7318; 186.4755–184.7880 \\  & 204.608–203.7630; 202.1693–201.3880; & 204.9130–203.4630; 202.4630–201.1068; \\  & 199.9005–199.1693; 197.7755–197.0880; & 200.1693–198.0967; 198.0255–196.8380; \\
84 & 195.7692–195.1192; 193.8817–193.2630; & 196.0130–194.8880; 194.1068–193.0380; \\  & 192.0567–191.4567; 190.3130–189.7505; & 192.2755–191.2442; 190.5255–189.5443; \\  & 188.6567–188.1192; 187.0817–186.5630; & 188.8568–187.9255; 187.2692–186.3817; \\  & 185.5692–185.0817 & 185.7505–184.9005 \\ \hline \hline \end{tabular} \({}^{1}\) selected optical subband for simulation.  
\end{table} 
Table 6: Calculated availability of optical subbands for two thresholds in a 20 km fronthaul path designed on the basis of G.655D non-zero dispersion shifted single-mode fiber. \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{_\(f_{RF}\) (GHz)_}} & \multicolumn{2}{c}{**Optical Subband (THz)**} \\ \cline{2-3} \cline{3-4}  & **3-dB** & **10-dB** \\ \hline
6 & 205.3380–184.4880 & 205.3380–184.4880 \\
12 & 205.3380–194.0192 & 205.3380–184.4880 \\
28 & 195.5130–190.1505 & 197.5317–188.3255 \\  & 203.2130–201.7692; 199.1130–197.8317; & 203.7505–201.2630; 199.5942–197.3755; \\
60 & 195.4505–194.2880; 191.9880–190.8255; & 195.8755–193.8817; 192.4193–190.4130; \\  & 188.6567–187.5942; 185.6130–184.6380 & 189.0443–187.2192; 185.9692–184.4880 \\  & 204.9317–204.1567; 202.6755–201.9505; & 205.2192–203.8755; 202.9442–201.6880; \\  & 200.5567–199.8755; 198.5630–197.9130; & 200.8130–199.6255; 198.8005–197.6817; \\
84 & 196.6693–196.0567; 194.8755–194.2943; & 196.8942–195.8380; 195.0942–194.0817; \\  & 193.1442–192.5317; 191.3505–190.7630; & 193.3755–192.3067; 191.5630–190.5505; \\  & 189.6380–189.0817; 188.0067–187.4755; & 189.8442–188.8817; 188.2005–187.2817; \\  & 186.4505–185.9442; 184.9567–184.4880 & 186.6380–185.7567; 185.1380–184.4880 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Calculated availability of optical subbands for two thresholds in a 20 km fronthaul path designed on the basis of G.655E non-zero dispersion shifted single-mode fiber. intervals [50], which limit the actual frequency bandwidth of the modulated OFDM signal. The maximum channel bandwidths, which are given in Table 8, are taken into account for the calculations. This ensures the consistency of the calculations and better visual analysis resulting from the numerology used in the 5G NR interface.