title: Novel configuration of finite-impulse-response filters tolerant to carrier-phase fluctuations in digital coherent optical receivers for higher-order quadrature amplitude modulation signals.
abstract: We propose a novel configuration of the finite-impulse-response (FIR) filter adapted by the phase-dependent decision-directed least-mean-square (DD-LMS) algorithm in digital coherent optical receivers. Since fast carrier-phase fluctuations are removed from the error signal which updates tap coefficients of the FIR filter, we can achieve stable adaptation of filter-tap coefficients for higher-order quadrature-amplitude modulation (QAM) signals. Computer simulations show that our proposed scheme is much more tolerant to the phase noise and the frequency offset than the conventional DD-LMS scheme. Such theoretical predictions are also validated experimentally by using a 10-Gsymbol/s dual-polarization 16-QAM signal.
authors.affiliation: Department of Electrical Engineering and Information Systems, The University of Tokyo, Tokyo, Japan. mori@ginjo.t.u-tokyo.ac.jp
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Mori
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.forename: Kazuro
authors.initials: K
authors.lastname: Kikuchi
mesh_terms: D000465:Algorithms; D005336:Fiber Optic Technology / Q000295:instrumentation*; D005374:Filtration / Q000295:instrumentation*; D006801:Humans; D008962:Models, Theoretical; D055096:Optical Devices; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013685:Telecommunications / Q000295:instrumentation*