Generalized CPM and DPM: digital angle modulation schemes with improved bandwidth efficiency

In digital angle modulation schemes the carrier is frequency modulated (continuous phase modulation) or phase modulated (digital phase modulation) by a waveform that is conventionally generated from the data sequence by a linear filtering operation. The concept is generalized by allowing a nonlinear dependence of the modulating signal on the data, making it possible to produce a signal with a narrower spectrum. The design procedure for the waveform is demonstrated for a signal with minimum out-of-band power. It is shown that the increase in bandwidth efficiency can be achieved without compromising the power efficiency of the signal