Multiple symbols soft-decision metrics for coded frequency-shift keying signals
This paper derives a novel multiple symbols soft-decision metrics for frequency-shift keying signals which are affected by additive symmetric alpha-stable (S alpha S) noise and fading. The approximate metric, which is for the case where channel state information (phases, amplitudes, and noise dispersion parameter) is unknown is obtained based on a generalized-likelihood ratio (GLR) approach. The metric is obtained in closed form and proved to be effective. The performances of the multiple symbols soft-decision metrics are compared numerically for a turbo-coded system. The proposed multiple symbols metric provides substantial improvement over earlier single-symbol metrics.
symmetric alpha-stable (s alpha s) noise multiple symbols detection generalized likelihood ratio (glr) fading channel