Space-division multiplexing over few-mode fibers is a promising solution to increase the\ncapacity of the future generation of optical transmission systems. Mode-dependent loss (MDL) is\nknown to have a detrimental impact on the capacity of few-mode fiber systems. In the presence of\nMDL, spatial modes experience different attenuations which results in capacity reduction. In this\nwork, we propose a digital signal processing solution and an optical solution to mitigate the impact\nof MDL and improve the channel capacity. First, we show that statistical channel state information\ncan be used for a better power allocation for spatial modes instead of equal launch power to increase\nthe system capacity. Afterwards, we propose a deterministic mode scrambling strategy to efficiently\nreduces the impact of MDL and improves few-mode fiber systems capacity. This scrambling strategy\ncan be efficiently combined with the optimal power allocation to further enhance the capacity.\nThrough numerical simulations of the average and outage capacities, we show that the proposed\ntechniques bring significant capacity gains.
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