Results: The three WDM channels were demultiplexed using digital filters. Digital backward propagation was performed offline using the split-step Fourier method to solve the coupled NLSEs. Clock recovery, phase estimation and Q-value calculation were performed after compensation of fibre impairments using DBP. The fibre parameters were determined by optimising the performance in the training experiments. The dispersion parameter was found to be 3.9 ps/nm/km by performing dispersion compensation for 80 km transmission. The fibre loss and nonlinear parameter were found to be 0.2 dB/km and 1.4/W/km by optimising the nonlinearity compensation after 800 km transmission. In DBP, the step size should be much smaller than the dispersion length LD=(b2Dn2)− 1 and nonlinear length LNL= Lsp [gPT Lsp