# Optical Channel Selection Avoiding DIPP in DSB-RFoF Fronthaul Interface
## 3 Calculation Results
### Optical Subband Selection for vRF Service
Tables 6 and 7 contain the results of searching for the available optical subbands also for two thresholds, but for optical paths built on the basis of optical fibers of the G.655 family. The optical fiber with a non-zero chromatic dispersion-shifted coefficient is characterized by a much lower dispersion coefficient, which makes the available areas of \begin{table}
\begin{tabular}{c c c c c c} \hline \(f_{RF}\) (GHz) & 6 & 12 & 28 & 60 & 84 \\ \(\Delta f_{0}\) (GHz) & 12.5 & 25 & 100 & 200 & 200 \\ \(\Delta\lambda_{0}\) (nm) & \(\sim\)0.1 & \(\sim\)0.2 & \(\sim\)0.8 & \(\sim\)1.6 & \(\sim\)1.6 \\ \hline \end{tabular}
\end{table} 
Table 4: Optical channel bandwidths for selected RF carriers in the vRF service (RFoF interface). \(\Delta\lambda_{0}\) is given for an optical carrier with a wavelength equal to 1550 nm. \begin{table}
\begin{tabular}{c c c} \hline \multicolumn{3}{c}{**Optical Subband (THz)**} \\ \cline{2-4} \multicolumn{1}{c}{} & \multicolumn{1}{c}{**3-dB**} \\ \hline
6 & 205.3380–184.4880 & 205.3380–184.4880 \\
12 & - & 205.3380–198.8568 \\
28 & 195.6068–191.4130 & 205.3380–203.4067; 197.2505–190.0130 1; \\  & 203.7692–202.5880; 200.3817–199.3067; & 204.2067–202.1693; 200.8718–198.9193; \\  & 197.2817–196.2880; 194.4130–193.4942; & 197.6442–195.9317; 194.9750–193.1630 1; \\  & 191.7505–190.8942; 189.2692–188.4692; & 192.0692–190.5880; 189.5630–188.1817; \\  & 186.9442–186.1942; 184.7630–184.4880 & 187.2255–185.9255; 185.0255–184.4880 \\  & 204.8630–204.2442; 203.0505–202.4567; & 205.0942–204.0192; 203.2630–202.2442; \\  & 201.3130–200.7505; 199.6567–199.1192; & 201.5255–200.5443; 199.8568–198.9255; \\  & 198.0755–197.5567; 196.5505–196.0567; & 198.2630–197.3692; 196.7318–195.8755; \\
84 & 195.0880–194.6130; 193.6817–193.2255; & 195.2630–194.4380; 193.8505–193.0567; \\  & 192.3255–191.8817; 191.0192–190.5942; & 192.4942–191.7255; 191.7755–190.4380; \\  & 189.7567–189.3442; 188.5380–188.18380; & 189.9130–189.1942; 188.6880–187.9942; \\  & 187.3568–186.9692; 186.2130–185.8380; & 187.5005–186.8317; 186.3505–185.7067; \\  & 185.1068–184.7442 & 185.2380–184.6130 \\ \hline \end{tabular} \({}^{1}\) selected optical subband for simulation.  
\end{table} 
Table 5: Calculated availability of optical subbands for two thresholds in a 20-km fronthaul path designed on the basis of G.652D or G.657A single-mode fiber. the optical subbands wider. It can be concluded that in the case of reduced dispersion or partially compensated, e.g., in a link belonging to the DWDM transit domain (for example Figure 4, link B), the number of useful optical channels is much greater. The calculation results presented in the tables and figures above relate to the transmission of unmodulated radio carrier in the links of the optical fiber network, but do not take into account the bandwidth of the radio frequency channel. The modulation of the radio carrier causes the appearance of frequency components that make up a broadband signal that must be within the range of a specific radio channel. The bandwidth of this channel depends on the modulation format, bit rate and the filtering criterion.