title: A complex-weighted, decision-aided, maximum-likelihood carrier phase and frequency-offset estimation algorithm for coherent optical detection.
abstract: We present a symbol-by-symbol coherent optical receiver, which employs a novel, complex-weighted, decision-aided, maximum-likelihood (CW-DA-ML) carrier phase and frequency offset estimator. The CW-DA-ML carrier estimator uses a CW transversal filter to generate a carrier reference phasor, and the filter weights are automatically adapted on-line by linear regression on the observed signals. A complete modulo-R reduced frequency offset estimation (FOE) range of ± R/2 is achieved, independent of modulation format, where R is the symbol rate. Carrier phase and frequency tracking is achieved rapidly. The acquisition speed of frequency offset in quaternary phase-shift keying (4-PSK) signals is more than 5 times faster than that of differential FOE. A constant penalty of approximately 1 dB at bit-error rate of 10(-4) is demonstrated for all frequency offsets in 4-PSK signals with laser-linewidth-symbol-duration product of 8 × 10(-5).
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore.
authors.forename: Adaickalavan
authors.initials: A
authors.lastname: Meiyappan
authors.forename: Pooi-Yuen
authors.initials: PY
authors.lastname: Kam
authors.forename: Hoon
authors.initials: H
authors.lastname: Kim
mesh_terms: D000465:Algorithms; D003627:Data Interpretation, Statistical; D016013:Likelihood Functions; D010783:Photometry / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D013685:Telecommunications