Study On The Technology Of Integrated Network Transmission Based On Laser

As an important supplement of terrestrial communication network,satellite communication plays an irreplaceable role in emergency communications and maritime communication. In recent years, with the rapid development of global Internet, satellite communication develops towards large capacity, high speed and broadband.. At the same time, it is urgent to develop the communication technology with more capacity, and how to increase the capacity of satellite communication is an urgent problem to be solved. However, the laser communication is seriously affected by atmospheric attenuation, atmospheric turbulence and background radiation. In order to transmit information reliably,modulation , demodulation and channel coding technology become the key technology in wireless laser communication. The key technology,LDPC coding technology has the advantage in this respect. At present,the satellite communication system based on laser is mainly Turbo code,binary LDPC code,while multi-band LDPC coding technology in satellite communications has not yet been widely used. The high-order LDPC codes have higher advantages in high-order modulation. Therefore, the high-order PPM modulation technique in laser communication can effectively improve the transmission efficiency, while the improved APPM modulation technology has more advantages. Therefore, LDPC coding technology and high-order XPPM modulation technology are the hotspots in the field of laser-based integrated network communication at home and abroad.Based on the study of the characteristics of atmospheric channel and modulation and coding technology in satellite-to-ground laser satellite communication, this paper focuses on the architecture of laser-based integrated network, the satellite-earth channel model and the modulation and coding scheme based on laser.The main innovation and research works are as follows:(1) Based on the analysis of satellite-atmosphere laser channel, the model of laser-based satellite-ground laser channel is established. The performances of laser-based satellite-ground laser channel model are simulated and analyzed. We also build the laser integration of the world network architecture, while build the corresponding simulation platform.(2) Based on the characteristics of laser-based satellite-ground laser channel, a modulation and coding scheme based on LDPC and NPPM is proposed and simulated. The results show that the algorithm Which has better performance under the satellite channel has better performance than Binary LDPC code combined with NPPM modulation and coding scheme.(3) Based on the study of APPM modulation technique, a modulation coding scheme based on improved APPM modulation technique combined with multi-band LDPC code is proposed. The performance of the scheme is simulated. The results show that compared with Binary LDPC code combined with NPPM modulation and coding scheme, in the same channel conditions, APPM modulation technology and multi-band LDPC code combined modulation and coding scheme transmission error smaller, you can get a smaller error rate.