Increasing the Spectral Efficiency of DDO-CE-OFDM Systems by Multi-Objective Optimization

• Published in: Journal of lightwave technology Vol. 37; no. 9; pp. 2155 - 2162
• Main Authors: de O. Rocha, Helder Roberto, Dias, Vinicius O. C., Da Veiga Pereira, Esequiel, Barbosa Nunes, Reginaldo, Segatto, Marcelo E. V., Silva, Jair A. L.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bandwidth; Computer simulation; Constant-envelope optical OFDM; Genetic algorithms; Indexes; Mapping; multi-objective optimization; Multiple objective analysis; NSGA II; Optical modulation; Optimization; Orthogonal Frequency Division Multiplexing; Peak to average power ratio; Phase modulation; Reduction; Spectra; spectral efficiency; Subcarriers
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2019.2898945

A multi-objective optimization was implemented to increase the spectral efficiency of direct-detection optical orthogonal frequency division multiplexing (OFDM) systems with constant-envelope (CE) signals. Based on a genetic algorithm, the optimization procedure evaluates the impact of fiber injection power in the reduction of the guard band between the optical carrier and the CE-OFDM signals, optimizing important parameters such as electrical phase modulation and optical modulation indices of the denominated DDO-CE-OFDM system. Simulation results show that a guard-band reduction around 40% was achieved in a 4 Gbps optimized DDO-CE-OFDM system with 16-QAM subcarrier mapping and -7 dBm fiber input power. Results obtained in an experimental proof-of-concept conducted to validate the optimization procedure show that this reduction can reach 66% according to a power penalty of ≈2 dB demanded by the inherent spectral broadening of CE-OFDM signals, after propagation over 40 km of standard single-mode fiber.