Counteracting 16-QAM Optical Fiber Transmission Impairments With Iterative Turbo Equalization

A turbo equalization (TE) scheme based on convolutional code and normalized least mean square equalizer for coherent optical communication links is proposed and experimentally demonstrated. The proposed iterative TE technique is proved effective for counteracting polarization-division-multiplexing 16 quadrature amplitude modulation impairments in dispersion uncompensated coherent transmission links. Gains exceeding one order of magnitude in terms of bit error rate are obtained in experimental validation up to 497 km-standard single mode fiber link transmission.