High-throughput architecture and implementation of regular (2, dc) nonbinary LDPC decoders

Nonbinary LDPC codes have shown superior performance, but decoding nonbinary codes is complex, incurring a long latency and a much degraded throughput. We propose a low-latency variable processing node by a skimming algorithm, together with a low-latency extended min-sum check processing node by prefetching and relaxing redundancy control. The processing nodes are jointly designed for an optimal pipeline schedule. This low-latency, high-throughput architecture is applied to a class of high-performance (2, d_c)-regular nonbinary LDPC codes constructed based on their binary images. A conflict-free memory is proposed to resolve data hazards caused by the non-structured nature of these codes. A complete (2, 4)-regular, (960, 480) GF(64) nonbinary LDPC decoder is demonstrated on a Xilinx Virtex-5 FPGA. The decoder delivers an excellent error-correcting performance at a 9.76 Mb/s coded throughput, representing a significant improvement of state-of-the-art extended min-sum decoder implementations.