Bit metric generation for Gray coded QAM signals

Distribution of L-values in gray-mapped M2-QAM: closed-form approximations and applications

“…Since a p,t and c p,t are constant within Z p,t , L k (r) is a piecewise linear form of r, a property which has also been observed in [11], [17]. To illustrate this, in Fig.…”

“…. , m − 1 [11]. Then, the real part of the transmission outcome is given by r = x I + η, where η ∈ R is a zero-mean, real, white Gaussian noise with variance N 0 /2 so the average signal-to-noise ratio (SNR) per QAM symbol is given by γ = 1 N0 .…”

Low Complexity Soft Decision Technique for Gray Mapping Modulation

“…For example, exact methods for 16-QAM and 64-QAM are proposed in [3] and [7] (the only difference between [3] and [7] is the constellation mapping style). Furthermore, a general exact method is proposed in [8], which can be applied to any order QAM modulation. The second is the simplified method, which reduces the complexity at the cost of additional performance degradation, such as those proposed in [3,4] (the only difference between [3] and [4] is the constellation mapping style).…”

“…However, since s + i and s − i are obtained via an exhaustive search over the whole constellation, the computational complexity involved in (3) is still much higher than that of hard decision. To avoid the exhaustive search of s + i and s − i , some modified techniques for QAM modulation are proposed in [3,4,7,8], which can be divided into two classes. The first is the exact method, which does not introduce additional distortion compared with (3).…”

Exploiting UEP in QAM-based BICM: interleaver and code design

“…The mapping considered here is based on the so-called binary reflected Gray code (BRGC) 2 [36], [37], so each symbol is a superposition of independently modulated real/imaginary parts [38]. Consequently, we focus on the equivalent M-PAM constellation (cf.…”