Abstract
Optical orthogonal frequency-division multiplexing offset quadrature amplitude modulation (O-OFDM/OQAM) system relaxes the orthogonal condition of the sub-carriers from the complex domain to the real field. Inter-symbol-interference (ISI) and inter-carrier-interference (ICI) could be suppressed by using filter banks with promising time-frequency-localization (TFL) properties. Therefore, cyclic prefix (CP) inserted between consecutive OFDM blocks could be removed for O-OFDM/OQAM system to improve system spectral efficiency. When passing through fiber channel, O-OFDM/OQAM faces serious intrinsic imaginary interference (IMI) induced by chromatic dispersion (CD), and fiber nonlinear effect, which would deteriorate system performance evidently. Fiber nonlinear effect induced interference is a great impairment for long haul transmission O-OFDM/OQAM system, and can not be equalized directly by using nonlinear equalization method designed for traditional optical OFDM. There is still much room for improvement of nonlinear equalization method for O-OFDM/OQAM. In this paper, we systematically study Volterra expansion based nonlinear equalization method (VENE) for O-OFDM/OQAM. We theoretically deduce simplified Volterra series expansion nonlinear transmission matrix (SVEM) for O-OFDM/OQAM based on mathematic deduction. With SVEM, intra channel nonlinear effect induced distortions could be modeled and estimated. By using specially designed pilot blocks, we obtain approximate solution of SVEM and perform effective VENE with very limited complexities. As shown in multiple Montel Carlo simulation results, nonlinear robustness for O-OFDM/OQAM has been improved significantly thanks to VENE, with various transmission distances and system parameters.
Highlights
Orthogonal frequency-division multiplexing (OFDM) has been widely applied as a typical multi-carrier modulation (MCM) technology for modern communication technology [1,2,3,4,5,6]
Fiber nonlinear effect induced interference is a great impairment for long haul transmission O-OFDM/OQAM system, and can not be equalized directly by using nonlinear equalization method designed for traditional optical OFDM
We systematically study Volterra expansion based nonlinear equalization method (VENE) for O-OFDM/OQAM
Summary
Orthogonal frequency-division multiplexing (OFDM) has been widely applied as a typical multi-carrier modulation (MCM) technology for modern communication technology [1,2,3,4,5,6]. Owing to the relaxation of the orthogonal condition from the complex field to the real field, an intrinsic imaginary interference (IMI) exists for OOFDM/OQAM systems when faced with the influence induced by CD, and fiber nonlinear effect [26]. There is few existing systematically discussion about nonlinear compensation methods based on receiver signal processing, and further research is quite necessary for future optical OFDM/OQAM development. In [44, 45], Volterra series has been utilized to analyze nonlinear effect induced interference for O-OFDM/OQAM in the preliminary stage. A Volterra expansion based fiber nonlinear effect equalization (VENE) method for O-OFDM/OQAM is systematically discussed and proposed. Based on detailed mathematical derivation, an O-OFDM/OQAM channel transmission matrix considering interference induced by nonlinear effects is established. In (10), we define the pure imaginary item Agnon(q1,q2,q3,p1,p2,p3)= as the nonlinear interference weight (NIW) for O-
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
