8 research outputs found
Successive Interference Cancellation for Bandlimited Channels with Direct Detection
Oversampling increases information rates for bandlimited channels with direct
detection, but joint detection and decoding (JDD) is often too complex to
implement. Two receiver structures are studied to reduce complexity: separate
detection and decoding (SDD) and successive interference cancellation (SIC)
with multi-level coding. For bipolar modulation, frequency-domain raised-cosine
pulse shaping, and fiber-optic channels with chromatic dispersion, SIC achieves
rates close to those of JDD, thereby attaining significant energy gains over
SDD and classic intensity modulation. Gibbs sampling further reduces the
detector complexity and achieves rates close to those of the forward-backward
algorithm at low to intermediate signal-to-noise ratio (SNR) but stalls at high
SNR. Simulations with polar codes and higher-order modulation confirm the
predicted rate and energy gains.Comment: Submitted to IEEE Journal of Lightwave Technology on December 15,
2022; Resubmitted to IEEE Transactions on Communications on September 9,
2023
Back-to-Back Performance of the Full Spectrum Nonlinear Fourier Transform and Its Inverse
In this paper, data-transmission using the nonlinear Fourier transform for jointly modulated discrete and continuous spectra is investigated. A recent method for purely discrete eigenvalue removal at the detector is extended to signals with additional continuous spectral support. At first, the eigenvalues are sequentially detected and removed from the jointly modulated received signal. After each successful removal, the time-support of the resulting signal for the next iteration can be narrowed, until all eigenvalues are removed. The resulting truncated signal, ideally containing only continuous spectral components, is then recovered by a standard NFT algorithm. Numerical simulations without a fiber channel show that, for jointly modulated discrete and continuous spectra, the mean-squared error between transmitted and received eigenvalues can be reduced using the eigenvalue removal approach, when compared to state-of-the-art detection methods. Additionally, the computational complexity for detection of both spectral components can be decreased when, by the choice of the modulated eigenvalues, the time-support after each removal step can be reduced. Numerical simulations are also carried out for transmission over a Raman-amplified, lossy SSMF channel. The mutual information is approximated and the eigenvalue removal method is shown to result in achievable rate improvements
Experiments on Bipolar Transmission with Direct Detection
Achievable information rates of bipolar 4- and 8-ary constellations are
experimentally compared to those of intensity modulation (IM) when using an
oversampled direct detection receiver. The bipolar constellations gain up to
1.8 dB over their IM counterparts.Comment: submitted to ECOC 202
Back-to-Back Performance of the Full Spectrum Nonlinear Fourier Transform and Its Inverse
Comparison of PAM-6 Modulations for Short-Reach Fiber-Optic Links with Intensity Modulation and Direct Detection
PAM-6 transmission is considered for short-reach fiber-optic links with
intensity modulation and direct detection. Experiments show that
probabilistically-shaped PAM-6 and a framed-cross QAM-32 constellation
outperform conventional cross QAM-32 under a peak power constraint.Comment: submitted to European Conference on Optical Communication (ECOC) 202