Generalized Concatenation of Encoded CPFSK Modulation

Abstract

Abstract. Using the principles of generalized concatenation we introduce a new design for coded M-ary CPFSK systems with modulation index h = l/M. This technique is based on a set partitioning method of inner CPFSK into nested subsystems with increasing free Euclidean distance which are combined with several outer convolutional codes having different error-correcting capabilities. In other words, we construct multilevel codes on the basis of inner modulation with memory, namely CPFSK. The new generalized concatenated constructions were simulated in an additive white Gaussian noise channel. The multistep decoding algoritm is described where for soft output decoding the well-known symbol-by-symbol maximum n posteriori probability (MAP) algorithm is applied to the inner CPFSK. A comparison of the generalized concatenated codes with the best known trellis-coded CPFSK schemes is also presented.