A generalized Nonlinear Fourier Transform (GNFT), which includes eigenvalues
of higher multiplicity, is considered for information transmission over fiber
optic channels. Numerical algorithms are developed to compute the direct and
inverse GNFTs. For closely-spaced eigenvalues, examples suggest that the GNFT
is more robust than the NFT to the practical impairments of truncation,
discretization, attenuation and noise. Communication using a soliton with one
double eigenvalue is numerically demonstrated, and its information rates are
compared to solitons with one and two simple eigenvalues.Comment: This work has been accepted for publication in IEEE/OSA Journal of
Lightwave Technology, 2018. Digital Object Identifier:
10.1109/JLT.2018.2875557. Copyright 2018 IEEE. Personal use of this material
is permitted. Permission from IEEE must be obtained for all other uses, in
any current or future medi
