Turbo coded continuous phase modulation

Continuous phase modulation (CPM) provides an attractive option for spectrally efficient communications systems. Turbo-coding combined with CPM has the potential to result in a spectrally efficient scheme that is also energy efficient in that it yields low error rates at low signal-to-noise ratios. In this paper we consider the concatenation of a turbo encoder and a CPM modulator which can be decoded and demodulated iteratively. For demodulation of the CPM signal we consider a design based on the Walsh signal space. Multiple iterations of the turbo decoder, feedback of a priori CPM symbol probabilities from the turbo-decoder to the CPM demodulator and multiple iterations of this turbo-decoder/CPM demodulator operation enhances the performance of the system.