Modified Cramer-Rao Bound for Clock Recovery in the Presence of Self-Phase Modulation
Journal article, 2012
We investigate the effect of nonlinear self-phase modulation (SPM) on clock recovery in long-haul coherent optical communication systems with low to moderate baud rates. We consider dual-polarization, multilevel quadrature amplitude modulation, and evaluate conventional timing estimators as well as a modified Cramer-Rao bound. As the latter is hard to compute in the presence of nonlinear channel impairments, we derive an approximate closed-form expression. Contrary to linear channel impairments, the nonlinear impairments can degrade the performance for higher input powers. In addition, the bounds exhibit oscillatory behavior due to the oscillations in the signal spectrum in the presence of SPM.
coherent optical communication
compensation
Clock recovery
optical-fibers
probability
amplifiers
noise
modified Cramer-Rao bound
timing
systems
design
fiber optics
Author
Ahmet Serdar Tan
Chalmers, Signals and Systems, Communication, Antennas and Optical Networks
Henk Wymeersch
Chalmers, Signals and Systems, Communication, Antennas and Optical Networks
Pontus Johannisson
Chalmers, Microtechnology and Nanoscience (MC2), Photonics
Erik Agrell
Chalmers, Signals and Systems, Communication, Antennas and Optical Networks
Magnus Karlsson
Chalmers, Microtechnology and Nanoscience (MC2), Photonics
Peter Andrekson
Chalmers, Microtechnology and Nanoscience (MC2), Photonics
Journal of Lightwave Technology
0733-8724 (ISSN) 1558-2213 (eISSN)
Vol. 30 16 2556-2562 6189720Subject Categories
Telecommunications
DOI
10.1109/jlt.2012.2196407