Research On Optimal Design Technology Of Space Division Multiplexing System Oriented To Energy Efficiency

In recent years,with the rapid development of emerging technologies,such as 5G mobile communications,big data,cloud computing,and high-definition mobile video,the demand for backbone network transmission capacity has increased sharply.Facing the upcoming "capacity crisis",it is urgently desired to develop new technology that can efficiently enhance the capacity of optical fiber communication systems.Nowadays the dimensions of time,wavelength,phase,and amplitude multiplexing technology of single-mode optical fiber communication system has gradually approached the capacity limit.Inspired by the parallel transmission of multiple input and multiple output,the few-mode fiber(FMF)based space division multiplexing system(SDM)is proposed,in which different modes in the FMF are multiplexed as independent channels to transmit signals in parallel so that the transmission capacity has been greatly increased,therefore attracting considerable attention.Energy efficiency(EE)and spectral efficiency(SE)are two important performance metrics in SDM system.In order to adapt to the development of green communications,the joint optimization of EE and SE is of great importance in FMF communication system.This paper focuses on the EE maximization and the EE-SE tradeoff of the few-mode fiber space division multiplexing communication system.The main contents are summarized as follows:Firstly,the problem of maximizing EE in a few-mode fiber space division multiplexing communication system is studied.According to the definition of energy efficiency,the amplifier spontaneous emission noise energy efficiency model and the spontaneous emission and nonlinear noise joint energy efficiency model are established,respectively.Through theoretical analysis of optimization problems,effects of the system transmission power and the number of spans on the transmission capacity and total power consumption is verified.Then,according to the fractional planning theory,the fractional form of energy efficiency is converted into a non-fractional form.The transmission power and the number of link spans are fixed respectively,which are optimized by Dinkelbach algorithm and Newton method,so as to obtain the optimal transmission power and the number of link spans corresponding to the maximum energy efficiency of the system.Simulation results verify the effectiveness of the proposed algorithm to maximize energy efficiency by optimizing the transmission power and the number of link spans.Secondly,the tradeoff optimization of the EE and SE of the few-mode fiber space division multiplexing communication system is studied.Taking into account that the energy efficiency and spectral efficiency of the SDM system do not always maintain the same trend,the system EE and SE models are established,and the expression of the relationship between the EE and the SE of the SDM system is derived,and then the Lambertian function is used to obtain the optimal spectral efficiency to maximizeof system energy efficiency.For the multi-objective optimization problem of maximizing EE and SE simutaneously,weighting factors are assigned to the system energy efficiency and spectral efficiency respectively,then the multi-objectives are transformed into single-objective optimization problem.Through theoretical derivation and analysis,the optimal transmission power,optimal number of spans and weighting factors for SDM system are obtained,respectively.Simulation results validate the theoretical analysis results.