A Low Complexity-High Throughput QC-LDPC Encoder

Abstract

This paper introduces hardware architectures for encoding Quasi-Cyclic Low-Density Parity Check (QC-LDPC) codes. The proposed encoders are based on appropriate factorization and subsequent compression of involved matrices by means of a novel technique, which exploits features of recursively-constructed QC-LDPC codes. The particular approach derives to linear encoding time complexity and requires a constant number of clock cycles for the computation of parity bits for all the constructed codes of various lengths that stem from a common base matrix. The proposed architectures are flexible, as they are parameterized and can support multiple code rates and codes of different lengths simply by appropriate initialization of memories and determination of data bus widths. Implementation results show that the proposed encoding technique is more efficient for some LDPC codes than previously proposed solutions. Both serial and parallel architectures are proposed. Hardware instantiations of the proposed serial encoders demonstrate high throughput with low area complexity for code words of many thousand bits, achieving area reduction compared to prior art. Furthermore, parallelization is shown to efficiently support multi-Gbps solutions at the cost of moderate area increase. The proposed encoders are shown to outperform the current state-of-the-art in terms of throughput-area-ratio and area-time complexity by 10 to up to 80 times for codes of comparable error-correction strength.