## 4 Simulation Results and Discussion  
Figure 2 shows the eye diagrams of the worst channel launched with 5 dBm power into the dispersion-managed link configured by the three random cases and the conventional scheme. The conventional scheme of Figure 2a corresponds to the case where the RDPS of all fiber spans is uniformly distributed by 0 ps/nm. For comparison, the results of Figure 2b-d were obtained by making the RDPS arrangement order of each fiber span in the former half the same as the following: \(1100\), \(900\), \(-600\), \(800\), \(1200\), \(-1000\), \(-400\), \(300\), \(100\), \(-900\), \(0\), \(-100\), \(-500\), \(-1200\), \(-1300\), \(-1100\), \(-700\), \(400\), \(700\), \(1300\), \(-300\), \(600\), \(1000\), \(-200\), \(200\), \(500\), and \(-800\) ps/nm. By comparing Figure 2b-d, it can be seen that the reception quality is excellent in the dispersion-managed link with the random-inverse distribution shown in Figure 2b. The compensation result in this case is an improvement on the conventional scheme of Figure 2a. These results are considered to be related to the basic condition for compensation through the midway OPC. In other words, it can be expected that the compensation of distorted channels through MSSI increases as the dispersion distribution becomes more symmetric around the midway OPC, and random-inverse corresponds to the distribution close to the symmetry. Unlike Figure 2a,b, the received pulse sequence of Figure 2c,d shows very severe amplitude fluctuations and phase fluctuations (i.e., timing jitter). In a pseudolinear system where chromatic dispersion and SPM of the nonlinear Kerr effect exist, optical pulse distortion occurs through the interaction of the two phenomena. That is, when the amplitude (intensity) of the optical pulse is changed due to chromatic dispersion, the nonlinear phase  
Figure 2: The eye diagrams. (**a**) conventional scheme, (**b**) random-inverse distribution, (**c**) random-follow distribution, and (**d**) all-random distribution. shift is generated according to the changed intensity, resulting in distortion of the optical pulse. Applying this mechanism to the eye diagram analysis shown in Figure 2, the eye diagrams in Figure 2c,d show that the specific random-follow and all-random distributions do not sufficiently compensate for the amplitude and phase distortion caused by the interaction between the chromatic dispersion and SPM experienced by the optical pulse. On the other hand, when the random-inverse distribution is applied, it can be confirmed that the mitigation of the amplitude and phase fluctuations of the optical signal due to the interaction of chromatic dispersion and SPM is effective. Since the EOP in the optical domain is the result of measuring the comprehensive eye closure of the optical pulse due to the amplitude change from the various causes, it is possible to analyze the compensation of the signal distortion due to SPM and chromatic dispersion by using the EOP. Thus, the compensation performance was analyzed through the EOP and, if necessary, timing jitter was also used. In the conventional scheme, the maximum launch power values that produce a 1-dB EOP and 2.5 ps of timing jitter were 4.13 and \(-\)0.13 dBm, respectively. Figure 3a,b show the maximum launch power values corresponding to the 1-dB EOP and 2.5 ps timing jitter, respectively. In Figure 3a,b, \"descending order number\" means that the resulting maximum launch power is sorted from the largest value to the smallest value, in order to facilitate comparative analysis. First, it can be seen from the result of Figure 3a that the EOP characteristics of the random-inverse distribution are overall better than the conventional scheme except for three cases. In particular, in timing jitter analysis, it can be confirmed from Figure 3b that the compensation characteristics in all 50 random-inverse distributions are superior to those of the conventional scheme.