Soft-Decision Metrics for Coded Orthogonal Signaling in Symmetric Alpha-Stable Noise

This paper derives new soft-decision metrics for coded orthogonal signaling in impulsive noise, more specifically symmetric-stable noise. For the case of a known channel amplitude and known noise dispersion, exact metrics are derived both for Cauchy and Gaussian noise. For the case that the channel amplitude or the dispersion is unknown, approximate metrics are obtained in closed-form based on a generalized-likelihood ratio approach. The performance of the new metrics is compared numerically for a turbo-coded system, and the sensitivity to side information of the optimum receiver for Cauchy noise is considered. The gain that can be achieved by using a properly chosen decoding metric is quantified, and it is shown that this gain is significant. The application of the results to frequency hopping ad hoc networks is also discussed.©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Michael R. Souryal, Erik G. Larsson, Bojan Peric and Branimir R. Vojcic, Soft-Decision Metrics for Coded Orthogonal Signaling in Symmetric Alpha-Stable Noise, 2008, IEEE Transactions on Signal Processing, (56), 1, 266-273.http://dx.doi.org/10.1109/TSP.2007.90677