METHOD FOR MODELING THE TRANSMISSION OF M-QAM SIGNALS OVER A FIBER-OPTIC PATH USING THE OPTICAL OFDM TECHNOLOGY
V. A. Vardanyan
Siberian State University of Telecommunications and Information Science, Novosibirsk, Russia
Keywords: fiber optic transmission systems, M-QAM, CO-OFDM, nonlinear phase noise, amplified spontaneous emission (ASE) noise, Q-factor, FEC
Abstract
A method has been developed for modeling the transmission of channel signals of the M-QAM modulation format using the CO-OFDM (Coherent Orthogonal Frequency Division Multiplexing) technology over a fiber-optic path operating in a nonlinear regime. Using the normalized analytical expressions obtained, signal distortions on the receiving side are modeled for given parameters of the transmission system, and the signal quality factor (Q-factor) is calculated based on a statistical analysis of the signal and noise parameters. The model helps to clearly represent the signal distortion in the constellation of signal points in the IQ-diagram for given parameters of the transmission system. The paper presents a model of a transmission system for an OFDM signal with a total rate of 4 Tbit/s using a standard single-mode optical fiber over distances of 80, 160, and 240 km. To achieve the maximum signal quality factor at such transmission distances, optimal levels of optical signal power of +5.5, +4, and +2.5 dBm have been found.
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