An Algorithm for AGC Optimization in MLSE Dispersion Compensation Optical Receivers

Communication systems are designed to provide reliable transmission of information and to cope with various channel imperfections. The amplitude of the received signal is attenuated depending on length and type of the transmission channel. Usually, automatic gain control is placed before the clock recovery in the receiver to combat signal power/swing variations. Optical channel impairments caused by chromatic dispersion, polarization mode dispersion, self-phase modulation, etc. can be efficiently compensated by the use of maximum-likelihood sequence estimation receivers. This paper describes an efficient AGC gain adjustment procedure using a gain control parameter that provides almost the optimum MLSE performance. A gradient algorithm is used to minimize the gain control parameter. Simulation results of 10.7 Gb/s intensity-modulated direct-detection nonreturn-to-zero optical channels disturbed by noise and chromatic dispersion show the advantage of the proposed algorithm.