| Submarine optical cable is the infrastructure of transnational communication in the current communication field and the most common communication transmission medium.Submarine optical cable has the following advantages:high communication quality,high bandwidth,long transmission distance and so on.In recent ten years,millions of kilometers of submarine optical cables have been laid.Therefore,submarine optical cable communication system has an irreplaceable position in communication.Now,with the gradual development of submarine optical cable technology,the concept of open submarine optical cable has sprung up.Open submarine cable transmission system refers to the joint access of submarine link terminal equipment of different equipment manufacturers to submarine optical cable link,which greatly improves the flexibility and scalability of submarine cable system.Different from the traditional submarine optical cable system,the open submarine optical cable breaks the limitation that the construction of submarine optical cable can only rely on a single equipment manufacturer.It has good compatibility,strong scalability and cost advantages.However,in the same submarine optical cable connection system,the modulation format,coding protocol,baud rate,roll off factor and input optical power of signals sent and received by submarine link terminal equipment produced by different equipment manufacturers may be different.Therefore,it is particularly important to evaluate the performance of scenarios with different channel parameters.This paper introduces the structure,characteristics and principle of open submarine cable communication system.Based on the above characteristics of submarine open optical cable communication system,this paper establishes an equivalent simulation model to evaluate the performance of nonlinear noise,and studies and verifies its accuracy,complexity and sampling resolution.The main work of this paper includes:First,the equivalent simulation evaluation model of transmission performance in optical transmission of open submarine optical cable system is established.The nonlinear damage in the signal transmission process of the open submarine cable communication system is studied,and the nonlinear damage in the transmission process of the submarine optical cable system is analyzed in the scenario where each channel has different modulation formats and supports flexible grids.An equivalent simulation model is established to analyze the nonlinear noise of the submarine open optical cable communication system with different modulation numbers and flexible grids.The simulation results show that the evaluation accuracy of the nonlinear noise power of the equivalent simulation model is 2.24dB higher than that of the analytical model when the modulation formats of each channel are different.In terms of calculation time,when there are 5 channels,the calculation time of the equivalent simulation model is already 400 seconds shorter than that of the generalized Gaussian noise model,and with the gradual increase of the number of channels,the time gap gradually increases.Second,a covariance-adaptive evolution-based optical power optimization strategy at the transmitting end of the submarine open optical cable communication system is proposed,and the optical power distribution at the transmitting end with the maximum average generalized signal-to-noise ratio of the submarine open optical cable communication system is found.The simulation results show that the optimized system performance is improved by 0.8dB compared to the transmitter power flattening scheme.Then,a covariance adaptive evolution based optical power optimization strategy at the transmitter end based on hierarchical optimization is proposed,and it is verified in different scenarios of channel priorities.The simulation results show that the channel with higher priority before and after optimization is improved by 1.19dB.The average generalized signal-to-noise ratio of the system is improved by 0.7997dB. |
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