首页|Performance comparison of partial-response square shaped signal with direct detection
Performance comparison of partial-response square shaped signal with direct detection
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NSTL
Elsevier
In this work, we investigate improving spectral efficiency with direct detection based partial-response square shaping, which generalizes partial-response pulse shaping and reduces width of power spectrum of signal under both linear and non-linear model assumption. For linear model, quadrature point bias of Mach-Zender modulator is used. For non-linear model, null point bias of Mach-Zender is used, however, non-linear pre coding and equalization are required. By comparing results obtained with linear model and non-linear model, we identify the factors influencing performance of short reach transmission. Results of experiment over a 25 km dispersion uncompensated link show following: Under non-linear model, performance issue is revealed with non-linear optical channel. Under linear model, for PAM4 modified-duo-binary with bias signal and PAM4 duo-binary, 2 b/s/Hz is achievable with 7% overhead hard decision decoding. Also, PAM4 modified-duo-binary with bias signal has 1 order lower bit error rate than PAM4 duo-binary, while theoretical analysis confirms the finding for short reach transmission, that non-linear equalization can recover information from coherent item and can suppress interference caused by self-beat item.
Direct detectionPartial-response square shapingQuadrature point biasNull point biasModified-duo-binaryDuo-binaryNyquist PAM4TRANSMISSIONPAM-4FRONTHAULVOLTERRAPHASEOFDMDML
NSTL
Elsevier
