Comments on “Bitwise Log-Likelihood Ratios for Quadrature Amplitude Modulations”

With reference to a recently published letter, the purpose of our contribution is two-fold. Firstly, to point out that, what is referred to as a new approximation function MinC (see Eqs. (5)-(8) of Park, 2015) has been previously published (see Eq. (12) of Papaharalabos et al., 2009). Secondly, we present additional related published works of ours, which have further investigated the subject of bitwise log-likelihood ratio (LLR) simplification in soft-output decoding, but have not been mentioned in Park, 2015.