Serially Concatenated Continuous Phase Modulation with Extended BCH Codes

Abstract

In this paper, serially concatenated continuous phase modulation (CPM) is considered. A concatenated structure consisting of a short extended BCH code as outer code is proposed, targeting a wide choice of spectral efficiencies, ranging from 0.75 to 2.25 bit/s/Hz. A two-step design procedure combining EXIT charts analysis and union bound techniques is used to optimize the association of the outer code and the CPM. An exhaustive study of several quaternary and octal CPM schemes is performed. The proposed concatenated structure offers very low error floors (frame error rate below 10-6) and good performance in the waterfall region for all spectral efficiencies. A significant improvement with respect to previous concatenated CPM schemes is shown. The envisaged application of the proposed scheme is the return link of broadband satellite communications.