Research On High-speed Turbo Decoding Algorithms In LTE System

Turbo code has been widely used in wireless communication systems for its excellent performance in low to moderate Eb/No region. To meet the requirements of up to 100Mbps information throughputs and low delay, it is valuable to study how to implement the high-performance and high-speed Turbo decoder effectively.This paper briefly introduces the principle of Turbo codes. Some theoretical analysis and performance comparisons are made about the existing decoding algorithms such as MAP, Log-MAP, Max-Log-MAP and SOVA. In order to improve the decoding device speed, the improvements of algorithms and configurations are discussed while taken decoding performance, hardware complexity and resource consumption into account. In terms of algorithm improvements, the SF-ML-MAP algorithm is proposed in order to enhance the decoding performance of Radix-4 Max-Log-MAP algorithm; the effective criterion HDA for stopping the iteration process is also adopted. In terms of the configuration improvements, the parallel sub-block algorithm is also adopted in this paper. After the particularly comparisons of the four methods of sub-block overall, CT, single-sliding window and double-sliding window, the optimum sub-block method is proposed in this paper, short block using CT algorithms while the long block with the double-sliding window methods. Meanwhile, in order to adapt to the parallel decoding method, the parallel CT interleaver has been designed in this paper which can effectively reduce the decoding delay.Finally, a high-speed decoder configuration has been designed and its modules have also been optimized.