| Due to the exponential growth in demand for multimedia services and cloud computing,the upcoming rapid development of various broadband Internet communication services such as virtual reality(VR)and big data Internet of Things technology has been fully integrated into people’s daily lives.The public’s demand for data transmission rate is growing exponentially.However,in the existing high-speed optical communication system,the transmission power of the system is limited,and only a limited optical signal-to-noise ratio can be obtained,resulting in low spectrum utilization,low receiver sensitivity,and poor resistance to fiber nonlinear effects.In order to improve the spectrum utilization and receiving efficiency of high-speed optical communication systems,wavelength division multiplexing passive optical network(WDM-PON)is a promising solution for heterogeneous access networks in the future,which can adapt to exponential Business growth and huge capacity demand.In this paper,the existing high-speed optical communication system is improved,and the WDM-PON system based on Probabilistic Shaping Intensity Modulation Direct Detection(IM-DD)and its key technologies are studied.The purpose is to improve spectrum utilization,improve receiver sensitivity,increase optical power and signal non-linear tolerance.1.In this paper,the probability shaping is realized by using Maxwell Boltzmann distribution model,and the PS-44 qam scheme is proposed for the first time.This scheme can effectively reduce the mapping complexity and improve the sensitivity of the receiver.At the same time,the number of different codewords of PS-44 qam mapping symbols is optimized.The experimental results show that PS-44 qam technology can improve the received power sensitivity of WDM-PON optical network unit,and the system data throughput and spectral efficiency are significantly improved.2.At the receiving of the probabilistic shaping optical transmission system,each symbol of the traditional high-order signal only maps a set of bit sequences.For the soft decision of the many-to-one mapping probability shaping high-order signal,the Gallager "many-to-one" mapping probability shaping is established correlation mechanism with LDPC encoding.In-depth discussion of the matching relationship between probabilistic demapping and LDPC decoding,and build a model based on bitinterleaved coding modulation-joint iterative decoding algorithm.After system experiment verification,as the number of iterations continues to increase,the system can significantly improve receiver sensitivity.3.In view of the complexity and hardware implementation cost of traditional arithmetic coding probabilistic shaping algorithms,in the DMT-WDM-POM system,the probabilistic shaping PS-44 QAM technology is combined with the bit-interleaved coding iterative decoding(BICM-ID)technology for the first time in the DMT-WDMPOM system.It overcomes the problem of constellation ambiguity caused by the overlapping of multiple symbols of PS-44 QAM,which leads to a serious degradation of system receiver performance.The feasibility of this optimization scheme in the DMT-WDM-PON system was verified in the laboratory communication system for the first time.In the system,it can be seen intuitively that the PS-44 QAM scheme has effectively improved the spectrum efficiency of the system. |
