A High-Throughput LDPC Decoder Architecture With Rate Compatibility

Abstract

This paper presents a high-throughput decoder architecture for rate-compatible (RC) low-density parity-check (LDPC) codes which supports arbitrary code rates between the rate of mother code and 1. Puncturing techniques are applied to produce different rates for quasi-cyclic (QC) LDPC codes with dual-diagonal parity structure. Simulation results show that our selected puncturing scheme only introduces the BER performance degradation of less than 0.2 dB, compared with the dedicated codes for different rates specified in the IEEE 802.16e (WiMax) standard. Subsequently, parallel layered decoding architecture (PLDA) is employed for high-throughput decoder design. While the original PLDA is lack of rate flexibility, the problem is solved gracefully by incorporating the puncturing scheme. As a case study, an RC-LDPC decoder based on the rate-1/2 WiMax LDPC code is implemented in the CMOS 65-nm process. The clock frequency is 1.1 GHz, and the synthesis core area is 1.96 mm <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{2}$</tex></formula> . The decoder can achieve an input throughput of 1.28 Gb/s at ten iterations and supports any rate between 1/2 and 1.