Carrier Frequency Recovery with CPM Modulations

Continuous phase modulation (CPM) encompasses a class of signaling schemes that conserve and reduce signal energy and bandwidth at the same time. Furthermore, the signals in this class have a constant envelope and therefore are very attractive in radio channels employing low-cost non-linear power amplifiers. Notwithstanding these favorable features, current CPM applications are still limited to a few simple modulation schemes (basically, MSK and its generalizations) because of implementation complexity and synchronization problems [1]. Research efforts are under way and advances in these areas are expected in the near future.