The Implementation Of Turbo Coding And Decoding System Based On DSP

Turbo code has been the focus of information and coding theory for its approach to Shannon limit since it was presented.It is also used as channel coding method in WCDMA,CDMA and TD-SCDMA 3G standard.At the same time the idea of iteration decoding is applied in the coding,modulating and signal detecting fields and so on.The Turbo coding and decoding system based on DSP is designed in the thesis including coding and decoding system based on DSP and serial port data transmitting and receiving system based on PC.Firstly the coding and decoding programs are burned into Flash ,then they would be loaded into DSP for operation through Bootloader after DSP is powered on,which means the DSP is made into a real Turbo coding and decoding system.A new Lookup-Log-MAP decoding algorithm is proposed on the basis of deeply studying the MAP,Log-MAP,Max-Log-MAP and Lookup-Log-MAP decoding algorithms. It is also applied in the Turbo coding and decoding system.The simulation results show that the decoding performance of the new algorithm is very close to the decoding performance of MAP. Meanwhile it reduces the decoding delay ,improves the decoding efficiency and is very easy to be realized on hardware platform.