| Atmosphere Laser Communication (ALC) refers to the technology of transmitting voice, data and graphics using laser beam. Because of its advantage of narrow transmit beam, small antenna size, broad information capability and high performance to price, it impressed many people in communication area. So it has good application foreground in dissolve of "The Last Kilometer Problem" and emergence communication. But in laser communication channel, because of being affected by many factors such as fog, rain, snow and atmosphere onflow, the signal's pulse is widen, the S/N falls and the error codes increases. So, it directly affects communication capability that we adopt the channel coding technology.We choose turbo code as channel code method according to the characteristic of channel of ALC. Turbo codes,for it's good performance in low S/N system ,is applied very usually in wireless and satellite communications. The experimentation shows that the use of turbo codes can lower the data-error-rate of atmospheric laser communication system.This paper introduces ALC system and it's development firstly, then, study several method of error control codes especially turbo code. Lastly, it discusses the implementation method of turbo codes.It adapted the algorithm of "pipelining" and in the design of decoding system which increases the decoding speed mostly. It choose the method of "Module design" that we can easily change some small aspects if we want to develop another turbo systems. |
