  By exploiting a causality property of the nonlinear Fourier transform, a
novel decision-feedback detection strategy for nonlinear frequency-division
multiplexing (NFDM) systems is introduced. The performance of the proposed
strategy is investigated both by simulations and by theoretical bounds and
approximations, showing that it achieves a considerable performance improvement
compared to previously adopted techniques in terms of Q-factor. The obtained
improvement demonstrates that, by tailoring the detection strategy to the
peculiar properties of the nonlinear Fourier transform, it is possible to boost
the performance of NFDM systems and overcome current limitations imposed by the
use of more conventional detection techniques suitable for the linear regime.
