Fig. 1. Suboptimal input distribution for P ( X = 0) ≥ q = 0 . 3 . TABLE I P$_{X}$$_{2}$$_{|}$$_{X}$$_{1}$ AND P$_{X}$ FOR q = 0 . 5 , c = 1 . 0 , SNR = 8dB . X$_{2}$ 0.0000 3.9281 -3.9281 7.1398 -7.1398 0.0000 0.8342 0.0605 0.0605 0.0224 0.0224 3.9281 0.4923 0.1852 0.1852 0.0687 0.0687 X$_{1}$ -3.9281 0.4923 0.1852 0.1852 0.0687 0.0687 7.1398 0.4923 0.1852 0.1852 0.0687 0.0687 -7.1398 0.4923 0.1852 0.1852 0.0687 0.0687 P$_{X}$ 0.7481 0.0919 0.0919 0.0341 0.0341 −6 −4 −2 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 0.66 0.17 0.42 0.26 0.03 0.5 0.23 0.02 0.48 0.24 0.02 0.34 0.25 0.07 0.01 0.34 0.24 0.08 0.01 0.32 0.24 0.09 0.01 0.3 0.23 0.1 0.02 0.3 0.19 0.11 0.04 0.01 0.3 0.16 0.11 0.06 0.02 SNR (dB) Probability mass points In this paper µ ∗ = ( X , α, β, P$_{X}$ ) is used to approximate the optimum distribution µ$_{0}$ through the maximizing L ( · ) . It is obvious that the optimized µ ∗ is symmetric about 0. Table I is the transition 30