Fast channel estimation and equalization scheme for offset-QAM OFDM systems
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Published Version
Date
2019
Authors
Zhao, Jian
Townsend, Paul D.
Journal Title
Journal ISSN
Volume Title
Publisher
OSA - The Optical Society
Published Version
Abstract
We show that the orthogonality between signal and intrinsic imaginary interference (IMI) in offset quadrature amplitude modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) can still be maintained under a certain condition even when the timing slots of different subcarriers are misaligned. We show that the phase and velocity differences over subcarriers induced by fiber dispersion satisfy this condition. Based on this, we propose a fast channel estimation and equalization scheme without prior channel information including coarse dispersion. We investigate the proposed scheme in a 40-Gbit/s offset-16QAM OFDM experiment and 240-Gbit/s polarization-division-multiplexed offset-16QAM OFDM simulations, both over 1200-km single-mode fiber. It is shown that the proposed scheme gives better performance, reduced overhead for the training sequence, and/or lower complexity than other schemes. We also compare offset-QAM OFDM with the proposed scheme and conventional OFDM, and show that in addition to the elimination of cyclic prefix overhead, offset-QAM OFDM gives better performance and longer transmission reach for a moderate/small number of subcarriers.
Description
Keywords
Amplified spontaneous emission , Optical networks , Optical signals , Phase recovery , Polarization mode dispersion , Quadrature amplitude modulation
Citation
Zhao, J. and Townsend, P. (2019) 'Fast channel estimation and equalization scheme for offset-QAM OFDM systems', Optics Express, 27(2), 15 pp. DOI: 10.1364/OE.27.000714