A Pragmatic Approach to Coded Continuous-Phase Modulation

In this paper, we show that a "pragmatic" approach to coded CPM schemes suffers from a significant capacity loss. This loss can be greatly reduced by choosing an appropriate mapping different from natural or Gray, adopted so far. We propose to add to the CPM modulator a linear feedback, optimized through capacity arguments, that permits to achieve performance within 1 dB from the CPM capacity.