LDPC Decoder of High Speed Multi-Rate DVB-S2 Based on FPGA

高速码率兼容DVB-S2的LDPC译码器的FPGA实现

¹ School of Electronics and Information, Northwestern Polytechnical University, Xi’an 710072, China
² China Academy of Space Technology(Xi'an), Xi’an 710100, China

Received: 12 April 2018

Abstract

A multi-rate LDPC decoder architecture for DVB-S2 codes based on FPGA is proposed. Through elementary transformation on the parity check matrices of DVB-S2 LDPC codes, a new matrix whose left is a QC sub-matrix and right is Transformation of Staircase lower triangular (TST) sub-matrix is obtained. The QC and TST are designed separately, therefore the successful experience of the most popular Quasi-Cyclic (QC) LDPC decoder architecture can be drawn on. While for TST sub-matrix, the variable nodes updating only need to be considered and the check nodes updating is realized compatibility with QC sub-matrix. Based on the proposed architectures, a multi-rate LDPC decoder implemented on Xilinx XC7VX485T FPGA can achieve the maximum decoding throughput of 2.5 Gbit/s at the 20 iterations when the operating frequency is 250 MHz, which demonstrates the highest throughput compared with the state-of-the-art works.

摘要

提出了一种基于现场可编码门阵列（field programmable gate Array，FPGA）的高速码率兼容第二代数字电视广播（digital video broadcast：second generation，DVB-S2）标准的低密度奇偶校验码（low density parity check codes，LDPC）译码器架构，通过对DVB-S2的LDPC码校验矩阵进行初等变换得到新的矩阵，由准循环（quasi-cyclic，QC）子矩阵和行变换下三角双对角子矩阵（transformation of staircase lower triangular，TST）组成。提出的译码器架构QC部分利用现阶段研究最多的准循环QC-LDPC译码器技术，而对于TST部分，只需兼容QC矩阵部分，提出的架构可以按照QC的架构而动态地改变TST的并行路数，而且分开存储TST与QC的更新消息，保证了码率兼容。基于Xilinx XC7VX485T FPGA的验证结果表明，5种码率兼容的DVB-S2 LDPC译码器，可到达时钟频率250 MHz，最大迭代次数20次，对应的译码器最大吞吐量为2.5 Gbit/s。