DECODING METRICS FOR SLOW FREQUENCY-HOPPED DPSK SYSTEMS

Abstract

A variety of soft-decision decoding metrics for slow frequency-hopped, differential phase shift keyed spread-spectrum systems are studied. The computational cut-off rates in the presence of partial band noise jamming for these metrics are analysed. The usefulness of various degrees of side information, the effectiveness of limiting and quantisation when side information is not available, and the importance of a judicious choice of the quantisation step size are demonstrated. Monte-Carlo type simulations for the system encoded by Odenwalder's (7, 1/2) code are conducted, the resulting BERs reveal that close approximations can be attained by estimations calculated from a known closed-form formula.