Terabits-per-Second Throughput for Polar Codes

Abstract

By using Majority Logic (MJL) aided Successive Cancellation (SC) decoding algorithm, an architecture and a specific implementation for high throughput polar coding are proposed. SC-MJL algorithm exploits the low complexity nature of SC decoding and the low latency property of MJL. In order to reduce the complexity of SC-MJL decoding, an adaptive quantization scheme is developed within 1–5 bits range of internal log-likelihood ratios (LLRs). The bit allocation is based on maximizing the mutual information between the input and output LLRs of the quantizer. This scheme causes a negligible $(0.1\ < \mathbf{dB})$ performance loss when the code block length is $N=\ 1024$ and the number of information bits is $K\ =\ 854$. The decoder is implemented on 45nm ASIC technology using deeply-pipelined, unrolled hardware architecture with register balancing. The pipeline depth is kept at 40 clock cycles in ASIC by merging consecutive decoding stages implemented as combinational logic. The ASIC synthesis results show that SC-MJL decoder has 427 Gb/s throughput at 45nm technology. When we scale the implementation results to 7nm technology node, the throughput reaches 1 Tb/s with under 10 mm2 chip area and 0.37 W power dissipation.