he system terminals and the need of maintaining a high line power to achieve the required high SN In the following section, we will select another option: we will accept a strong distortion of the 100 Gbit/s signal due to system filters that we will then try to recover through an ISI equalizer. This will allow us to maintain the number of levels lower thus simplifying the system terminals. 9.5.3.1 Draft Design and Power Budget Reducing the number of levels quite below 64 means to increase the bandwidth above the value for which the system has been designed thus causing pulse distortion due to narrow optical filtering. Thus pulse spreading due to tight optical filtering increases the ISI parameter and, with a suitable design of an equalizer, it could be at least partially corrected at the receiver. Telecommunication Networks TABLE 9.12 Transmitter and Receiver Data for 8-DPSK Designed to Use a 10 Gbit/s Line 100 Gbit/s 64-4QAM NRZ on a 10 Gbit/s Link System length 3000 km Channel speed 100 Gbit/s 64-DPSK-Coherent Detection, span length 70km, Super FEC with 11 dB gain Channel spacing 100 GHz Extended C band, 38 nm in the third window, that is 4560 GHz, 45 channels at 100 Gbit/s Ideal SN (dB) (B = 4.8R S Optical to electrical bandwidth ratio Ideal SNo (dB) Margin in dB Transmitter dynamic range DPSK transponder with phase TiNbLi modulator Linear crosstalk Gaussian selection filter (single stage AWG), B = 1.2RS Channel spacing If = 3RS (see Figure 5.2) Nonlinear crosstalk Use of SSMF to thwart FWM, post-compensation with DCF SPM and chromatic dispersion 10 Gbit/s optimized dispersion map (see Table 6.5) interplay Per channel optical and electronic dispersion compensation at the receiver. Used an MLSE equalizer (see Figure 9.49) MLSE equalizer at the receiver Aging System Margin Nonlinear depolarization Polarization unbalance Polarization depending losses, connectors misalignments, Total SN post code 29.65 dB Code gain (dB) Total SN pre-code 18.65 To verify the transmitted power for SPM assessment To confirm with simu