Study And Realization Of Turbo Decoding In WCDMA Uplink Processing

Turbo coding and decoding scheme is one of the key technologies of the 3G systems. Turbo code is outstanding of its high error-correcting performance in high noise application environment. For high-rate packet switch service, WCDMA adopts Turbo coding scheme to improve the anti-noise capability of the signal.This paper begins with the principle of channel coding theory, Turbo coding and decoding, and presents in-depth analysis on the channel coding and multiplexing process of WCDMA on the base of 3GPP physical protocol. Then simulations on Turbo coding and decoding processes with different decoding algorithms, different frame length and iterations have been performed using MATLAB. The curves of Turbo decoding performance is plotted for comparison and analysis.Finally, We realize demultiplexing and decoding of WCDMA based on TI's high performance TMS320C6488 DSP. Firstly, we introduce the basic characters of TMS320C6488, how to optimize DSP code and how to use DSP/BIOS, especially about task scheduling. Then the main process flow and task scheduling design of WCDMA uplink demultiplexing and decoding are presented in detail. Configuration of TCP2 decoding parameters, the scaling algorithm upon TCP2 input data, configuration of EDMA3 transfer parameters and the optimized scheme of generating Turbo internal interleaver are also explained. In the end, Test of Turbo decoding performance of TCP2 is performed.