title: On the optimum signal constellation design for high-speed optical transport networks.
abstract: In this paper, we first describe an optimum signal constellation design algorithm, which is optimum in MMSE-sense, called MMSE-OSCD, for channel capacity achieving source distribution. Secondly, we introduce a feedback channel capacity inspired optimum signal constellation design (FCC-OSCD) to further improve the performance of MMSE-OSCD, inspired by the fact that feedback channel capacity is higher than that of systems without feedback. The constellations obtained by FCC-OSCD are, however, OSNR dependent. The optimization is jointly performed together with regular quasi-cyclic low-density parity-check (LDPC) code design. Such obtained coded-modulation scheme, in combination with polarization-multiplexing, is suitable as both 400 Gb/s and multi-Tb/s optical transport enabling technology. Using large girth LDPC code, we demonstrate by Monte Carlo simulations that a 32-ary signal constellation, obtained by FCC-OSCD, outperforms previously proposed optimized 32-ary CIPQ signal constellation by 0.8 dB at BER of 10(-7). On the other hand, the LDPC-coded 16-ary FCC-OSCD outperforms 16-QAM by 1.15 dB at the same BER.
authors.affiliation: University of Arizona, Department of Electrical and Computer Engineering 1230 E. Speedway Blvd, Tucson, AZ 85721, USA. taoliu@email.arizona.edu
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Ivan B
authors.initials: IB
authors.lastname: Djordjevic
mesh_terms: D000465:Algorithms; D003195:Computer Communication Networks / Q000295:instrumentation*; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D055096:Optical Devices; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*