Demodulation and Decoding of Trellis Coded Continuous Phase Modulations in an Incoherent Mobile Radio Environment

Digital communication systems using Trellis Coded-Continuous Phase Modulations (TC-CPM) have been shown to be power efficient, both for coherent and incoherent detection. In this paper some techniques for the incoherent detection of TC-CPM signals in a radio-mobile environment are studied. Two different differential decoding algorithms for the detection of TC-CPM are presented. The first one is a Viterbi algorithm characterised by a reduced number of states when compared with the classical coherent Viterbi detector. The second one is a modified SAN(B) algorithm for the incoherent detection of convolutionally encoded CPM over a mobile radio environment. Comparisons with the coherent Viterbi decoder show that the proposed algorithms are quite attractive, especially in the case of frequency non-selective radiomobile channels.