Software-Defined Fiber Optic Communications for Ultrahigh-Speed Optical Pulse Transmission Systems

We introduce the cognitive dynamic system (CDS) as the brain of software defined optical communications systems (SDOCS). The cyber processing layer of smart SDOCS based on CDS can be a good solution to control quality of transmission (QoT) by cognitive symbol decision-making and finding the best trade-off between transmission reach and capacity in nonlinear SDOCS. We modify the perceptor of CDS so that the posterior can be extracted directly without using the Bayesian equation to obtain a significant reduction of the CDS complexity. The low-complexity and simple algorithmic design of the proposed cognitive decision making (CDM) can make it suitable for SDOCS applications since CDS does not require the previous knowledge of the fiber optic transmission system parameters. Then, we experimentally demonstrate the performance enhancement of ultrahigh-speed optical pulse transmission system upgraded with the preceptor of CDS as the proof-of-concept of SDOCS. Experimental results show 1.3 dB enhancement in Q-factor for a 1.28 Tbaud (10 Gbaud 128 OTDM) fiber optic system with polarization-multiplexed 64 quadrature amplitude modulation (QAM) at 15 Tbits data rate over a 150 km long fiber link. The CDS provides good reliability over system disturbances such as clock recovery intolerance.