Energy-efficient gear-shift LDPC decoders

In this paper, we present LDPC decoder designs based on gear-shift algorithms, which can use multiple decoding algorithms or update rules over the course of decoding a single frame. By first attempting to decode using low-complexity algorithms, followed by high-complexity algorithms, we increase energy efficiency without sacrificing error correction performance. We present the GSP and IGSP algorithms, and ASIC designs of these algorithms for the 10 Gbps Ethernet (2048,1723) LDPC code. In 65nm CMOS, our pipelined GSP decoder achieves a core area of 5.29mm², throughput of 88.1 Gbps, and energy efficiency of 39.3 pJ/bit, while our IGSP decoder achieves a core area of 6.00mm², throughput of 100.3 Gbps, and energy efficiency of 14.6 pJ/bit. Both algorithms achieve error correction performance equivalent to the offset min-sum algorithm. The throughput per unit area and energy efficiency of these decoders improve upon state-of-the-art decoders with comparable error correction performance.