f our design procedure. Telecommunication Networks TABLE 6.5 Realistic Penalty Analysis for Long-Haul 40 Gbit/s Dense Wavelength Division Multiplexing System Long-Haul 40 Gbit/s DWDM System System length 2000 km Channel speed 40 Gbit/s Suitable EDFAs, span length 50km, RS(255,239) Channel spacing 200 GHz Extended C band, 38 nm in the third window, that is 4560 GHz, 22 channels @ 40 Gbit/s Ideal SN, (dB) (B =2R) Optical to electrical bandwidth ratio Ideal SNo (dB) Penalties in dB Transmitter dynamic range SFF MSA using tunable CW laser and TiNbLi modulator APD + shot noise Linear crosstalk Gaussian selection filter (single stage AWG), Bo=2R Channel spacing Af=5R (see Figure 6.16) Nonlinear crosstalk Use of SSMF to thwart FWM and XPM, post-compensation with DCF. NRZ modulation Under compensation of chromatic dispersion at Unchirped NRZ modulation Chromatic dispersion Residual dispersion 500 ps/nm. Per channel electronic dispersion compensation at the receiver per 500 ps/nm. Used an FFE nine taps + DFE four taps (see Figure 5.56) 4ps, NRZ modulation FFE-DFE at the receiver (see Figure 5.57) Aging System margin Polarization effects PDL, connectors misalignments, etc. TOTAL SN post code 28.4 dB Code gain (dB) Total SNo precode To confirm with simulation Having a maximum power per channel equal to 5 dBm means to fix the output saturated power of our amplifiers at 18.5 dBm instead of 20 dBm. In practice, such a regulation can be done via software on every amplifier; thus, we can imagine using the same amplifier of Table 6.2 with a different software configuration. We will need a high SN, since we want a total length of at least 2000 km; thus, we will chose a span length of 50km SO to reduce the ASE, as much as possible, within the con- straint of a cost within market targets. The transmitter and the receiver power budget equations are satisfied with a laser power of 13 dBm and a transmitter loss of 15 dBm, for the transmitter and a receiver loss of 10 dBm and an APD sensitivity at 40 Gbit/s of -20 dBm and an APD saturat