In this paper, we report on the performance comparison of all-optical signal processing methodologies to compensate fiber transmission impairments, namely chromatic dispersion and nonlinear distortion caused by the Kerr effect, in a coherent 112 Gbit∕s dual-polarization 64 bit quadrature amplitude modulation system over 800 km standard single-mode fiber. We numerically compare optical backward propagation (OBP) with optical phase conjugation (OPC) techniques, namely. mid-link spectral inversion,