## 3 Heterogeneous MLR Network of the NG-PON Type
The receiving eye diagrams of the seven channels and their BER value that can be seen in the Figures 8a,b, 9a,b, 10a,b and 11a,b, in their region of the one mark (upper part of the diagrams), show little data dispersion as a consequence of the noise present in the signal, In the region of the opening of the eye (center of the diagrams), symmetry is shown in the time crosses, which indicates that in this case the chromatic dispersion is not a degrading factor of the system, indicating that the defined parameters in transmission (such as the power), and the medium, such as the compensation and the distance, are adequate so that the signals do not present degradation and are not considerably affected by the linear and non-linear effects of transmissions through optical fiber. In addition, the use of different modulation formats directly impacts noise tolerance while increasing the number of symbols per time unit, thus, Mach-Zehnder modulators are almost exclusively used in 40/100 Gbps transport systems, due to its good performance to control modulations and the possibility of independently modulating the intensity and phase of the optical field. Figure 8: Eye diagram, first channel 2.5 Gbps. (**a**) Transmission eye diagram; (**b**) Eye diagram at reception. Figure 7: Rectangular throughput optical spectrum. Figure 11: Eye diagrams. (**a**) Eye diagram, channel 3 (2.5 Gbps); (**b**) Eye diagram, channel 2 (10 Gbps). Figure 4:0 Eye diagrams, 40 Gbps channel. (**a**) Transmission eye diagram; (**b**) Eye diagram at reception. Figure 4:1 Eye diagrams, first channel 10 Gbps. (**a**) Transmission eye diagram; (**b**) Eye diagram at reception. The spectral efficiency of the 2.5 Gbps, 10 Gbps and 40 Gbps channels was calculated in Tables 3-5. Table 6 shows the spectral efficiency analysis of the hybrid system, corresponding to a throughput of 70 Gbps. Figure 4:2  
Figure 4:3  
Figure 4:4  
Figure 4:5  
The spectral efficiency for this heterogeneous network, where a throughput of 70 Gbps is transmitted, did not present the results that were expected in comparison with other heterogeneous networks previously studied where 2.5 Gbps and 10 Gbps channels were combined, reaching a throughput of 40 Gbps, since the spectrum used is increased in vain, because low-speed channels do not contribute significantly to throughput and spectrum is wasted in the required spacing between them. Table 7 summarizes the most important characteristics of the network model proposed in this article. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \(\mathbf{Av}\) & \(\mathbf{C_{N}}\) & \(\mathbf{C_{Total}}\) & \(\mathbf{C_{Pro}}\) & \(\mathbf{\eta_{ded}}\) & \(\mathbf{\eta_{dist}}\) \\ \hline \multirow{2}{*}{\(\Delta\)V1 25 GHz} & \multirow{2}{*}{2.5 Gbps} & 4 CH of 2.5 Gbps & & 5.18 GHz & \\ \cline{3-5}  & & 10 Gbps & 10 Gbps & 9.88\% & 321.59 GHz \\ \hline \multirow{2}{*}{\(\Delta\)V1 50 GHz} & \multirow{2}{*}{10 Gbps} & 2 CH of 10 Gbps & Distance: 80.5 km & 37.25 GHz & \\ \cline{3-5}  & & 20 Gbps & 5.64 Tbps/km & 26.85\% & \\ \hline \(\Delta\)V3 & \multirow{2}{*}{40 Gbps} & 1 CH of 40 Gbps & 138 GHz & 21.77\% \\ \cline{3-5}  & & 40 Gbps & 232.15\% & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Hybrid system measurement and control variables. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \(\mathbf{Av1}\) & \(\mathbf{C_{N}}\) & \(\mathbf{C_{Total}}\) & \(\mathbf{C_{Pro}}\) & \(\mathbf{\eta_{ded}}\) & \(\mathbf{\eta_{dist}}\) \\ \hline \multirow{2}{*}{25 GHz} & \multirow{2}{*}{2.5 Gbps} & 4 CH of 2.5 Gbps & Distance 80.5 km & 5.18 GHz & 80.18 GHz \\ \cline{3-5}  & & 10 Gbps & 0.81 Tbps/km & 9.88\% & 12.47\% \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Measurement and control variables of the four channels of 2.5 Gbps.