Step-GRAND: A Low Latency Universal Soft-Input Decoder

GRAND features both soft-input and hard-input variants that are well suited to efficient hardware implementations that can be characterized with achievable average and worst-case decoding latency. This paper introduces step-GRAND, a soft-input variant of GRAND that, in addition to achieving appealing average decoding latency, also reduces the worst-case decoding latency of the corresponding hardware implementation. The hardware implementation results demonstrate that the proposed step-GRAND can decode CA-polar code (128,105+11) with an average information throughput of 47.7 Gbps at the target FER of
$< 10^{-7}$
. Furthermore, the proposed step-GRAND hardware is 10 × more area efficient than the previous soft-input ORBGRAND hardware implementation, and its worst-case latency is
$\frac{1}{68} \times$
that of the previous ORBGRAND hardware.