The Design And Implementation Of Ccsds Turbo Decoder

1948, Claude Shannon’s landmark paper "A mathematical theory of communication" start the field of channel coding. Decades after that, the channel coding field invented several coding scheme, but not until the90s of20th century, the invention of Turbo code and the rediscovery of LDPC code brought breakthrough to the field.After nearly30years development, Turbo code has been used in a wide range of applications, the commercial wireless communication network such as the33G standards:WCDMA, CDMA2000, TDSCDMA and its Long Term Evolution also use Turbo codes as its code scheme in physical layer; and in deep space communication, due to the extreme transmission condition, the communication environment is very complicated, it also use excellent Turbo codes.Turbo code uses maximum posterior probability algorithm, its performance is near Shannon limit, but because of the complexity, its delay is too high, to achieve the requirements of real-time communication, the industry has proposed parallel decoding algorithm, modified decoding algorithm and other methods.This dissertation use CCSDS standard Turbo code as research object, and its main work is as below:describe the background and development of Turbo code, analyze the basic principle of Turbo code, including the architecture of encoder and iterative decoder, deduce the decoding algorithm of Turbo code in detail, including Log-Map, Max-Log-Map, Scale-Max-Log-Map; analyze the key performance factors of Turbo code in different directions; based on Intel CPU’s SIMD instructions,it propose a state parallel computing method, and implement the algorithm with C program language using the parallel method, after the analysis of the results, we conclude that with the state parallel computing Log-Map algorithm, the throughput is improved3times without performance loss.