A Multi-Gbps Fully Pipelined Layered Decoder for IEEE 802.11n/ac/ax LDPC Codes

Abstract

This paper presents a fully pipelined layered decoder architecture for IEEE 802.11 n/ac/ax LDPC codes, free of idle cycles. Several decoder architectures for such codes have emerged in the literature featuring throughputs in the multi- Gbps range. The proposed architecture surpasses the highest reported throughput for IEEE 802.11 n/ac/ax LDPC codes. This is achieved 1) algorithmically, by implementing the layered LDPC decoding schedule, and 2) architecturally, by optimizing register-based memories for IEEE 802.11n/ac LDPC codes and implementing an idle-cycle-free pipelined single-codeword datapath decoder. Register-based memories provide full bandwidth access to read and write all messages of a layer in one clock cycle. Single-codeword processing in the datapath significantly reduces memory overhead compared to other architectures that process multiple codewords to boost throughput at the expense of a larger footprint. The proposed architecture is synthesized in 40 nm CMOS process for IEEE 802.11 n/ac, rate 1/2 LDPC codes. The decoder occupies an area of 0.38 mm2, runs at a frequency of 780 MHz, and achieves a throughput of 4.2 Gbps.