| With the rapid growth of information technology,a variety of new business come to emerge such as international conference,IPTV,cloud services,etc.Higher requirements are put forward in order to satisfy the transmission capacity.Based on a latest survey,there is an exponential growth for network transmission capacity.People were working hard to improve the system capacity.Communication transmission system is transferred from the electric transmission to the optical fiber transmission with better performance.In order to improve the capacity of the single mode fiber,various kinds of communication has been applied to the optical fiber link,such as high order modulation,DWDM and related optical communication,etc.These technologies can effectively enhance the capacity of the transmission distance and link of the system,but the nonlinear characteristics of single-mode fiber set a limit to its capacity,whose transmission capacity approaches to the Shannon limit.It's high time to adopt a new method to increase transmission capacity.Reuse technology based on the model of two polarization is a commonly used method,which is easily combined with other skills and can double the link transmission capacity.As with the model reuse technology based on multimode fiber,it can improve system capacity with different spatial patterns.Each pattern in this model reuse technology is orthogonal,so it can be used as an independent channel for signal transmission.Compared with the single mode fiber,multimode optical fiber can bear larger capacity signal transmission,with larger field area and higher nonlinear tolerance.It is of great value to research the multimode fiber polarization multiplexing mode multiplexing transmission system.However,model coupling happens due to the different manufactures,bending link and reversing connection.In addition,modal dispersion emerges due to the different transmission speed.Mode coupling and dispersion will both harm the signals.So the digital signal processing need to compensate the damage of the link.This thesis gives a research on the core skills of polarization multiplexing mode multiplexing transmission system based on multimode fiber.An detailed analysis on the multimode optical fiber transmission link is given with a back-end digital signal processing method.The novelty in this paper is as follows:Firstly,a transmission system design is given,which is based on multimode fiber polarization multiplexing mode multiplexing transmission system.A thorough study is made into the sender module and the receiver module,which includes the research on the key components such as polarization beam splitter,polarization beam splitter,converter,multiplexer and so on.In addition,a transmission link model is put forward.Some damage factors in the transmission link,such as mode coupling,dispersion mode interactions between the effects on the useful signal,is researched.And the simulation verification is also provided.Furthermore,this thesis puts forward an adaptive step RLSCMA algorithm,which has faster convergence speed compared with RLS or CMA algorithm.It is based on the commonly used adaptive LMS algorithm and RLS algorithm.At last,the receiver digital signal processing method is studied based on the analysis of transmission system link,which includes quasi static compensation of chromatic dispersion,as well as to the model,and the damage generated by cross between factor of MIMO equalization.To sum up,this thesis designs a more suitable for multimode fiber of MIMO equalizer,which is based on modulus between the damage factor between the core and damage effect and mechanism of different,and they are targeted for equilibrium.The MIMO is equalizer for mold core joint system with better balance effect. |
PDF Full Text Request