An improved pragmatic approach to coded modulation design with multiple carrier frequencies

Abstract

An improved pragmatic approach to coded modulation design which provides higher coding gains especially for noisy channels is proposed in this paper. The basic pragmatic approach previously proposed by Viterbi et al. (1989) is adopted, but integrated with the multiple carrier frequency concept. An optimum rate 1/2 convolutional code is used to design a general coded modulation system which can be implemented easily. This new scheme is shown to perform much better than the original pragmatic approach at low to modest signal-to-noise ratio (SNR) conditions. It provides significant coding gains for practical channel conditions but at a price of slight loss in asymptotic coding gain (ACG). The system performance with respect to various design issues, factors and parameters including the signal constellations, mapping rules, ACG's and minimum Euclidean distances are analysed and illustrated in detail. Extensive simulation results also support the concept and demonstrate the validity of the analysis.