Research On Wireless Optical Communication Channel Coding And Modulation

Free space optical communication (Free Space Optical,FSO) refers to the use of laser beams in the atmosphere as a carrier for voice, data, image information bidirectional transfer of a technology, it has good security, information capacity, high transfer rate, flexible networking and low cost advantages.Space optical communication has broad application prospects in defense, civil and other fields, and has become a high-capacity, secure, wireless communications research hotspot. Due to laser transmission will be affected by the atmospheric attenuation effect?atmospheric turbulence effect?the influence of background light and many other factors, leading to atmospheric channel fading and multipath interference phenomenon, these influences led that atmospheric wireless optical communication link exists different degree of decline in the quality.Therefore, researching and development with high anti-jamming performance, high-speed optical communication coding techniques become an important issue.This paper first reviews the spatial development of optical communication technology,introduces its advantages, analyzes and compares its key technologies. Second, the atmospheric random channel modeled for the subsequent chapters channel parameter set to provide a reference.Then,this paper introduces a method of irregular LDPC codes based on the theory of LDPC codes. Analysis and comparison the performance of OOK, PPM and DPIM, the result of simulation shows that PPM modulation is more suitable for application in wireless optical communications,so this article will choose the PPM modulation as modulation way of wireless optical communication system. Based on the MATLAB simulation software, error correction performance under different parameters for the simulation, providing appropriate parameters for below decoding algorithm. Article applied this kind of irregular LDPC codes to a PPM demodulation and joint iterative decoding algorithm of LDPC codes, simulation results through the performance of wireless optical communication system has improved significantly.Finally, In the Quartus ? simulation platform, article realized the irregular LDPC code encoder and decoder by choosing Altera Stratix series models for EP2S15F672I4 chip and using Verilog hardware programming language. And by the combination of the Quartus ? and MATLAB software simulation, the hardware simulation results were tested.