ision Feedback Equalizer 5.8.3.2 Maximum Likelihood Sequence Estimation Equalizers 5.8.4 Pre-Equalization and Pre-Distortion Equalizers 5.8.5 Forward Error Correction 5.8.5.1 FEC Definition and Functionalities 5.8.5.2 BCH and the Reed-Solomon Codes 5.8.5.3 Turbo Codes 5.8.5.4 ITU-T OTN Standard and Advanced FEC 5.8.5.5 FEC Performances 5.8.6 Content Addressable Memories Interface Modules and Transceivers 5.9.1 MSA Transmitting-Receiving Modules 5.9.2 Transceivers for Carrier-Class Transmission 5.9.2.1 SFP Transceivers for Telecommunications 5.9.2.2 XFP Transceivers for Telecommunications References Transmission Systems Architectures and Performances Introduction Intensity Modulation and Direct Detection Transmission 6.2.1 Fiber-Optic Transmission Systems 6.2.1.1 Wavelength Division Multiplexing 6.2.1.2 Transmission System Performance Indicators 6.2.2 Ideal IM-DD Transmission 6.2.3 Analysis of a Realistic Single-Channel IM-DD System Contents 6.2.3.1 Evaluation of the BER in the Presence of Channel Memory 6.2.3.2 NRZ Signal after Propagation 6.2.3.3 RZ Signal after Propagation 6.2.3.4 Realistic Receiver Noise Model 6.2.3.5 Performance Evaluation of an Unrepeated IM-DD System 6.2.4 Performance of Non-Regenerated NRZ Systems 6.2.4.1 Dispersion-Compensated NRZ IM-DD Systems 6.2.5 Performance of Non-Regenerated Return to Zero Systems 6.2.6 Unrepeated Wavelength Division Multiplexing Systems 6.2.6.1 Linear Interference in Wavelength Division Multiplexing Systems 6.2.6.2 Nonlinear Interference in Wavelength Division Multiplexing Systems 6.2.6.3 Jitter, Unperfected Modulation, Laser Linewidth, and Other Impairments Intensity Modulation and Direct Detection Systems Using Optical Amplifiers 6.3.1 Long-Haul and Ultra-Long-Haul Transmission: Performance Evaluation 6.3.2 Design of Long-Haul Transmission Systems 6.3.2.1 Erbium-Doped Optical Fiber Amplifier Amplified Systems Design 6.3.2.2 Long-Haul Transmission at 40 Gbit/s 6.3.2.3 Long-Haul Transmission: Realistic Systems Characteristics 6.3.3 Design of Ultra-Long-Haul Transmi