Research On The Transmission Performance Of LDPC And PPM In Wireless Laser Communication Systei

In recent years, with the maturity of the laser devices and the need forultra-broadband high-speed wireless communications technology, wireless lasercommunication (WLC) has become a hotspot technology and attracted much attention.WLC is seriously affected by the factors such as atmospheric attenuation, atmosphericturbulence, and background radiation and so on. In order to achieve reliable informationtransmission, modulation/demodulation and channel coding techniques have become thekey technology in the wireless laser communication system.Because PPM and LDPC code have a lot of advantages, in this paper, for studyingthe performance of the whole system, PPM combined with LDPC is studied in wirelesslaser communication system. Firstly, the simulation model of wireless lasercommunication system is established. On this basis, using OOK and PPM format, theBER with and without LDPC is analyzed and compared respectively. In order to studythe performance of LDPC in the PPM format WLC system, LDPC with different codelength, code rate and iteration number is simulated and analyzed respectively. Here, thecheck matrix of LDPC is constructed randomly, and the logarithmic domain BPdecoding algorithm is adopted. Simulation results show that WLC system using PPMand LDPC has better performance.