## 4 Simulation Results
For 32 number of channels, the symbol rate has to be dropped to 3.2 GSym/s to ensure that the BER performance is under the limit. Figure 7 discusses the power penalties due to nonlinearities at \(-3\), \(-2\), and \(-1\) ps\({}^{3}\)/km nonlinear dispersion. The system performance in terms of BER for various values of available OSNR is presented in Figure 8, in the presence of nonlinearities. The results show that lower values of BER can be achieved at low OSNR values using the proposed compensation technique. The performance behavior of the proposed set up is explored based on eye diagram analyzer and visual inspection of the RF analyzer. Figure 9a-c represent the eye diagram at the receiver end, when eight, 16, and 32 channels are used for the considered WDM system, respectively, where no compensation technique is applied to mitigate nonlinearities. Thus, the look of the eye diagrams are worse which defines that error ratio is high in the received signals as the number of channels are increased. While, Figure 9d-f eye diagrams denote the proposed model outcomes for 8, 16, and 32 channels respectively, which show the improvement in performance with the presented DSP technique. The quality factor (Q-factor) is measured from the eye diagrams to be five using the quantitative measurement methods provided in [31]. The Q-factor is estimated by taking the ratio between sum of eye opening (decision point to the edge) to the sum of RMS noise at the edge. The RF spectrum visualizer is used for calculating and displaying electrical signals in the RF frequency domain. It can display the signal intensity and power spectral density. Figure 10a-d depict the improvement with the involvement of DSP module for 16 and 32 number of channels. Figure 10a,b diagrams present the received spectrum after the long haul transmission of the considered high capacity optical network without the compensation of nonlinearities, while Figure 10c,d explain the system performance after the application of the proposed DSP technique to compensate nonlinearities. The blue trace represents the signal and grey trace shows the nonlinear noise. The reduction in nonlinearities can be clearly observed by comparing Figure 10a with Figure 10c that the amplitude of nonlinear noise is reduced by up to 15 dB. From the detailed discussion of the simulation results in this section, it is concluded that, the with the help of low cost and simple proposed model, the results show that high data rates beyond 100 Gbps can be easily transmitted up to 300 km range of length with low BER. Figure 3: Effect of nonlinearities for different sequence lengths versus input optical power against BER, using eight and 16 channels (exclusively) with 25 GHz channel spacing. Figure 2: Nonlinear effective area against bit error rate (BER) for different channels and symbol rates. Figure 4: BER performance comparison of with and without nonlinearities compensation at 2, 4, and 6 dBm launch power in terms of different transmitted fiber lengths. Figure 5: Power penalty due to nonlinearities at different channel spacings. Figure 8: BER performance for different values of available optical signal-to-noise ratio (OSNR). Figure 6: Reference wavelength against BER at different number of channels. Figure 7: Power penalty at various transmitted fiber lengths using \(-3\), \(-2\), and \(-1\) ps\({}^{3}\)/km nonlinear dispersion. additional hardware and it can easily be implemented in the real-time systems using DSP assisted receiver. The projections made by the presented simulation analysis to transport of 100 Gb/s data rate over 300 km of transmission distance can be really useful for design engineers to extend the current optical backhaul lengths and upgrade the data rate capacity.