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Published on: March 20, 2017
Dispersion-enhanced phase noise effects on reduced-guard-interval CO-OFDM transmission
Qunbi Zhuge1, Chen Chen, David V Plant
1Department of Electrical and Computer Engineering, McGill University, Montreal, QC, Canada. qunbi.zhuge@mail.mcgill.ca
Abstract:
Unlike conventional CO-OFDM systems, we show in this paper that reduced-guard-interval (RGI) CO-OFDM systems experience subcarrier-dependent phase noise (PN) from the local oscillator laser. This phenomenon manifests in RGI-CO-COFM systems because the chromatic dispersion (CD) induced walk-off becomes comparable to the OFDM symbol length. We term this phenomenon the dispersion enhanced PN (DEPN). In this work an analytical study of the impact of DEPN on CO-OFDM transmission is conducted. We develop a system-level analytical model and calculate the variance of the dispersion-induced subcarrier-dependent phase rotation term (PRT) using two different distribution patterns of pilot subcarriers (PS). Moreover, we present a bit error rate (BER) estimator to quantify the system performance degradation due to PRT. Numerical simulations are then performed to verify the analytical model. Finally, we propose a grouped maximum-likelihood (GML) phase estimation approach to mitigate the DEPN impairment, and demonstrate a 0.7-1.7 dB SNR improvement at BER=10⁻³ for typical 100 Gb/s RGI CO-OFDM systems.
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