In Space Division Multiplexing (SDM) system, in order to achieve mode demultiplexing, it is necessary to adopt Multiple Input Multiple Output (MIMO) equalization scheme at the receiving end. As the number of transmission modes or transmission capacity increases, the computational complexity of MIMO increases significantly, resulting in high power consumption. Therefore, it is necessary to reduce the computational complexity of MIMO equalization.

We propose a frequency-domain joint equalization technique based on Cyclic Prefix (CP) to reduce the complexity compared with a traditional frequency-domain independent equalization and a separate dispersion compensation module in few-mode fiber short-range transmission systems.

Based on the few-mode fiber model in VPI simulation platform, we build a 6×6 few-mode fiber transmission system to verify the advantage of computational complexity reduction of the proposed technology. The simulation results show that, the performance and computational complexity reduction of different CP ratios are also different. Under the same simulation conditions, when the proportion of CP is larger, the reduction of computational complexity is also larger, vice versa. With the same performance, the computational complexity of the frequency-domain equalization scheme with CP accounting for 11.11%is only 15.29%of that of the traditional frequency-domain equalization scheme based on block convolution.

Compared with the traditional frequency-domain equalization combined with a separate dispersion compensation module, the proposed frequency-domain equalization with CP has lower computational complexity.