Low-Complexity Memory Access Architectures for Quasi-Cyclic LDPC Decoders

Ming-Der SHIEH  Shih-Hao FANG  Shing-Chung TANG  Der-Wei YANG  

IEICE TRANSACTIONS on Information and Systems   Vol.E95-D   No.2   pp.549-557
Publication Date: 2012/02/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E95.D.549
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Computer System
error control coding,  low-density parity-check (LDPC) codes,  quasi-cyclic (QC) LDPC codes,  partially parallel architecture,  VLSI design,  

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Partially parallel decoding architectures are widely used in the design of low-density parity-check (LDPC) decoders, especially for quasi-cyclic (QC) LDPC codes. To comply with the code structure of parity-check matrices of QC-LDPC codes, many small memory blocks are conventionally employed in this architecture. The total memory area usually dominates the area requirement of LDPC decoders. This paper proposes a low-complexity memory access architecture that merges small memory blocks into memory groups to relax the effect of peripherals in small memory blocks. A simple but efficient algorithm is also presented to handle the additional delay elements introduced in the memory merging method. Experiment results on a rate-1/2 parity-check matrix defined in the IEEE 802.16e standard show that the LDPC decoder designed using the proposed memory access architecture has the lowest area complexity among related studies. Compared to a design with the same specifications, the decoder implemented using the proposed architecture requires 33% fewer gates and is more power-efficient. The proposed new memory access architecture is thus suitable for the design of low-complexity LDPC decoders.