Area-Efficient QC-LDPC Decoding Architecture With Thermometer Code-Based Sorting and Relative Quasi-Cyclic Shifting

Abstract

The 5G New-Radio (NR) communication standard requires high throughput and low latency, so low-density parity-check (LDPC) codes, which have higher inherent parallelism and lower decoding complexity than turbo codes, were adopted as the main coding method for data channels. In traditional LDPC min-sum decoders, the check node unit was realized using a sorting unit based on the min-tree structure. However, this structure resulted in high hardware complexity and long latency. To address this issue, we propose a new sorting method based on the thermometer code-based number system. Additionally, we introduce a new LDPC decoding architecture that reduces the number of QSN stages from two to one, significantly lowering the shifting logic complexity needed to support different lifting sizes. This is achieved by using relative shift amounts instead of absolute shift amounts specified in the parity check matrix. The proposed decoder implemented using a partially parallel structure in a 65nm CMOS technology satisfies the various operation modes and the throughput requirements of the 5G NR standard, and boasts a higher normalized throughput than state-of-the-art LDPC decoders.