Research And Implementation Of High Throughout Turbo Decoder For LTE System

The Third Generation Partnership Project (3GPP) started a long-term evolution(LTE) project in response to the competition of the broadband wireless access market atthe end of2004. The project aimed to increase the spectrum efficiency, improve the datarate and decrease the transmission delay of the system. Because of its excellent BERperformance, Turbo codes were selected as the LTE channel coding scheme. Therefore,in order to meet the data transmission rate up to hundreds of megabytes of the LTEsystem, it has important and practical significance to research Turbo decoder with highperformance and high throughput.This paper analyzes the encoding and decoding principle of Turbo codes and givesthe LTE Turbo encoding scheme. Some theoretical analysis and performancecomparisons are made about the existing decoding algorithms such as MAP, Log-MAP,and Max-Log-MAP. Then the Max-Log-MAP algorithm with minimal complexity andsuboptimal performance is improved. In order to increase the system throughput, thearticle introduces the CRC-HDA stop iterative criterion that can effectively reduce theaverage number of decoding iterations and the Radix-8algorithm which can deal withthree bits per clock cycle by merging three consecutive times. In order to reduce thedecoding delay, the parallel decoding structure and sub block pipeline sliding windowalgorithm are adopted, and the parallel conflict free QPP interleaver is used. Thenthrougth the fixed-point simulation, the data width of the parameters is got for thehardware design.Finally, based on the above algorithms and structures, high throughput LTETurbo decoder is designed and optimized.