  Modern applications are driving demand for ultra-reliable low-latency
communications, rekindling interest in the performance of short, high-rate
error correcting codes. To that end, here we introduce a soft-detection variant
of Guessing Random Additive Noise Decoding (GRAND) called Ordered Reliability
Bits GRAND that can decode any short, high-rate block-code. For a code of $n$
bits, it avails of no more than $\lceil\log_2(n)\rceil$ bits of
code-book-independent quantized soft detection information per received bit to
determine an accurate decoding while retaining the original algorithm's
suitability for a highly parallelized implementation in hardware. ORBGRAND is
shown to provide similar block error performance for codes of distinct classes
(BCH, CA-Polar and RLC) with low complexity, while providing better block error
rate performance than CA-SCL, a state of the art soft detection CA-Polar
decoder.
