Design of low PAPR 2-Soliton NFDM transmit signals with optimal constellations for NFT-based high-speed optical communication

Abstract

Optical Fiber Communication is known for its extremely high data-carrying capacity among all the existing transmission technologies. However, its capacity to the fullest is restrained by the effects of nonlinearity, thereby urging nonlinear compensation. In this paper, we have attempted to enhance the performance of Nonlinear Frequency Division multiplexing (NFDM) based nonlinearity compensation, a recent attraction due to its high throughput nature. Here, we design optimal transmit signals, emphasizing lowering the Peak to Average Ratio (PAPR). With appropriate investigation, optimal eigenvalue and Quadrature Amplitude Modulation (QAM) constellations for encoding have been procured that aid in constructing low PAPR NFDM signals. To upgrade the optimal QAM design, two novel Spiral QAM models, Model I and Model II are proposed that diversify signal envelopes in addition to lowering the PAPR. This improves the overall fault tolerance of the NFDM system. For a 2-eigenvalue NFDM system, using the proposed constellations, the PAPR is reduced by 0.24 dB (Model I) and 1.42 dB (Model II), compared to the conventional scheme. Thus, we have designed optimum NFDM transmit pulses and subsequently accomplished a high performing 10 Gbps NFDM system using the proposed constellation models.