Analysis And Realization Of The Performance Of Polar Code Coding And Modulation In Near-Earth Weak Turbulent Channel Wireless Optical Communication

Ever since polar codes have been proved to have the ability to strictly reach the channel capacity,the research interest of domestic and foreign scholars on polar codes has been very high.With the International Mobile Telecommunications Organization 3GPP determining the polarization code as the standard for 5G control channels in 2016,the polarization code has been further applied.However,from the literature published at home and abroad,the research on polarization codes in the field of wireless optical communication,especially based on atmospheric turbulent channels,is not much,so the development of polarization code encoding in near-earth weak turbulent channels has been carried out.The analysis and experiment of modulation performance have certain research significance.Before proceeding with further research on polar codes,some basic knowledge of information theory including communication system models and common channels are briefly explained.Then,the generation principle of the polarization code is analyzed and researched.The three parts that form the polarized channel: channel synthesis,channel splitting,and final channel polarization are analyzed in detail.Later,the paper introduced the atmospheric turbulence effect that can cause large interference during the transmission of space optical communication,and also explained the near-ground weak turbulence effect and its channel based on the polarization code transmission channel studied in this paper.The gamma-gamma model of near-earth weak turbulent channels is completed.Subsequently,the paper introduces several methods of constructing polar codes: Papanicolas parameter estimation method,density evolution method,Monte Carlo construction method,and Gaussian approximation method.And the channel selection reliability is simulated and analyzed.In the decoding of polar codes,Belief Propagation decoding,Successive Cancellation decoding and its derivative decoding scheme Successive Cancellation List decoding are explained in detail,and the decoding delay and complexity of these three decoding schemes are matlab Simulation analysis and comparison.After analyzing the coding and modulation scheme of the polarization code and completing the modeling of the turbulent channel,the paper finally adopted the Monte Carlo construction method for information selection and then adopted the On-Off Keying modulation method,and then used the improved BP decoding algorithm in gammagamma.The communication link structure of the distributed turbulent channel model,and the design of the hardware is completed using verilog,which verifies the correctness and rationality of the research goal of the thesis.