Study On The Key Technologies Of Beyond100Gb/S Optical Fiber Transmission

With the development and popularizing of IOT, cloud computing, FTTH and3G mobile broadband service, the capacity of backbone transport network is rising rapidly. Backbone transport network is the keystone of network infrastructural facilities construction in our country, and its bandwidth demand is increasing gradually, so enlarging the capacity of backbone transport network is imperative. To the DWDM transmission system, one of the efficient methods for increasing the total capacity is increasing the capacity of single channel. Today, the deployment of100Gb/s commercial transmission system is in process, and the study of next generation high-speed transmission system is to start. Based on the past experience of increasing of information rate, the information rate of next generation transmission system will be4times or10times of today’s rate. Hence,400Gb/s and1Tb/s transmission system becomes the research focus. In this paper, the key technologies of beyond100Gb/s optical fiber transmission system are studied. The research contents are C band capacity of system, system plan of beyond100Gb/s transmission and DSP algorithms respectively, and a number of innovative research achievements are gain. The main work and innovative contributions are listed as follows.1、The choice of400Gb/s or1Tb/s in beyond100Gb/s transmission system is an important problem that we need to solve. A method for calculating C band capacity based on the highest level of modulation format calculated by optimal launch power is proposed when the influence of OSNR and fiber nonlinearity is considered. Employing the method, we have analyzed three typical systems in which the channel rates are112Gb/s,480Gb/s, and1.2Tb/s respectively. The result of the analysis is shown as follow. Considering6.25GHz guard interval between the adjacent channels,480Gb/s system can afford the biggest system capacity in C band when distance of transmission without electric regenerator is shorter than1000km. While the distance is longer than2200km, the1.2Tb/s system has the biggest capacity. If there is no guard interval between the adjacent channels, when the transmission distance is shorter than2300km, the112Gb/s system has the biggest C band capacity. When the distance is longer than2300km, the capacities of three systems are same.2、In this paper, focusing on the beyond100Gb/s transmission, in order to choose the system scheme reasonably, several mainstream system schemes are compared in detail from three aspects:system performance, system cost and the feasibility of technology. The result of contrast is shown as follow. To480Gb/s transmission system, when the transmission distance is longer than1000km, multi-band QPSK-E/O-OFDM system in which the subcarries are produced by transmitting end DSP is a better system scheme. When the transmission distance is shorter than1000km, single-band16QAM-E/O-OFDM system is better. To1.2Tb/s transmission system, Nyquist WDM system base on QPSK modulation format is better. A simulation of1.2Tb/s Nyquist WDM system is carried out, and the transmission distance is3200km. In addition, the effectiveness of DSP algorithms such as JSTRE proposed by our group is demonstrated employing the experiment of of1.2Tb/s Nyquist WDM system.3、To remove the signal injury caused by ICI which is induced by CD, we propose a low complexity differential pre-coding CD compensation scheme based on star16QAM modulation format. The scheme could remove the signal injury caused by ICI effectively. Comparing with channel estimation algorithm based on training sequence, the calculation complexity of scheme we proposed will reduce more than a half.4、In beyond100Gb/s O-OFDM transmission system, the higher PAPR of the signal not only can arouse fiber nonlinearity easily but also can destroy the performance of linear field modulation of MZM. An algorithm based on arcsin transformation is proposed, which can increase the output power of optical transmitter. In the simulation system, the output power of optical transmitter could rise about2dB using the algorithm. In single-band16QAM-E/O-OFDM system, we have optimized the number of additional phase of SLM algorithm and improved the method of transmission of additional phase information. Employing simulation, the effectiveness of improved algorithm is illuminated.