| Recent years,China's science and technology have developed rapidly.Whether cloud computing,artificial intelligence,or big data,massive data transmission is required,and the demand for network bandwidth is increasing day by day.The Metro Area Network(MAN)is a key part of the provincial backbone network the users' access network.In order to solve the problem of increasing bandwidth requirements and impact problems of the metropolitan area network,it is not enough to just adopt the optical fiber to the home(FTTH)access network.To meet people's needs,we must broaden the entire information "highway" and accelerate the city's regional network.In 2015,the overall migration of transmission and switching technologies in China's telecom industry has been completed,which greatly increases the capacity and speed of data transmission over the network.However,these networks use the same network architecture that existed since the beginning of the packet network.As new demands grow and change,the existing network architecture cannot support these new requirements.In addition,the increase of the transmission rate inevitably imposes higher requirements on the processing speed of the encoding,the complexity of the hardware implementation,and the overall power consumption.For example,optical transmission at a rate greater than 10 gigabits per second is susceptible to fiber impairments such as dispersion,polarization-mode dispersion,and nonlinear effects.Therefore,while increasing the transmission rate,the negative effects of other factors need to be suppressed as much as possible.Fiber channel modeling and forward error correction coding and related technologies are studied.Most of the existing optical communication networks use fixed data rates,and their link budget analysis is aimed at the worst transmission conditions.This results in insufficient utilization of system resources.Therefore,it is necessary to conduct research on rate adaptive technology and make the transmitter adjust the data rate dynamically.Based on the research of high-speed metropolitan area optical network architecture,this dissertation focuses on the fiber channel modeling scheme,rate-adaptive forward error correction coding and modulation schemes in high-speed metropolitan area optical networks,and forward correction based on polar codes.To meet the high-speed,large-capacity transmission requirements of short-distance and medium-distance,to meet the requirements of reasonable modeling of optical fiber channels,and to meet the bit error rate requirements of low complexity,low cost,high coding gain forward error correction coding modulation,we've done the research work as follows:1.Research on high speed metropolitan area optical network based on optical transport network technologyBased on the study of high-speed metropolitan area optical network architecture and key technologies,an architecture scheme for high-speed metropolitan area optical networks was established.The scheme uses optical transport network technology and wavelength division multiplexing to describe the composition of high-speed metropolitan area optical networks.Simulation analysis of the eye diagram,the maximum Q factor value,the minimum bit error rate and other performance indicators are done.The research results show that the scheme can achieve a single wave of 10 Gigabits per second.When there are more than 10 wavelengths,a 100 Gigabit per second transmission target near zero-bit error rate can be achieved.2.Research on fiber channel modeling based on high speed metropolitan area networkBased on the study of the transmission characteristics of the optical fiber channel and the scalar nonlinear Schrodinger equation,an improved vector form of the optical pulse transmission equation is proposed.The numerical solution of the vector nonlinear Schrodinger equation is given.Based on those above,a wavelength division multiplexing based fiber channel model under high-speed metropolitan area network is established.Simulation of a 10-kilobit-per-second(OOK)signal-to-kilometer transmission optical fiber system with dispersion compensation,on-off keying non-return-to-zero code(OOK-NRZ)signal of 100 km metropolitan area ring fiber system and a 10 Gigabit differential quadrature phase shift keying(DQPSK)scheme without dispersion compensation are done.The results show that the schemes can well describe the high rate medium/short-distance fiber channel,and also accurately predict the bit error rate performance.3.Research on rate adaptive forward error coded modulation schemesBased on the research of rate adaptive coding,a rate-adaptive forward error correction coded modulation scheme based on variable decoding iterations number,a rate-adaptive forward error correction coded modulation scheme based on non-binary code,and a rate-adaptive forward error correction coded modulation scheme of layered coding are proposed.The error performances of the three schemes under different modulation formats and system parameter settings are simulated.Results show that the scheme based on layered coding performs outstandingly.At a rate of 1E-3,a coding gain of about 7.3 dB is achieved,which is 1-2 dB more than a single coding scheme.Compared with the conventional forward error correction scheme,it has a higher coding gain at a reasonable complexity.Also it has a variety of rate adaptation capabilities and high decoding accuracy.4.Research on forward error correction coded modulation scheme based on Polar CodeBased on the research on polar code,an improved polar-code-bit-interleaved-coded-modulation(Polar-BICM),an improved polar-code-multilevel-coded-modulation scheme(Polar-MLCM),polar-code-trellis-coded-modulation scheme(Polar-TCM)are proposed.Simulations on the bit error rate performance of three schemes under different optical signal to noise ratios are done.Results show that the Polar-TCM scheme combines the advantages of polar code and TCM with lower complexity and higher coding gain,and overcoming the shortcomings of high delay,high complexity,and error propagation of Polar-MLCM,and the capacity loss of Polar-BICM. |
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