Log-Likelihood Ratio Calculation for Iterative Decoding on Rayleigh Fading Channels Using Padé Approximation
Figure 2
Comparison of true LLR and approximated LLRs (Taylor3, Taylor5, and Pade23) for the uncorrelated flat Rayleigh fading channel with unknown CSI and . From (a), Pade23 gives nearly the same values as the true function for various channel output , and Taylor5 shows inaccurate as becomes large. From (b), accuracy of Pade23 and Taylor5 is good especially for small . But accuracy of them is different for large ; that is, Pade23 shows the best accuracy in three methods, but Taylor5 shows the worst accuracy.
