A novel class of continuous-phase modulation (CPM) with separable phase property

Continuous phase modulation (CPM) is a power and bandwidth efficient modulation yet the receiver complexity is usually too high. Therefore, receiver complexity reduction techniques become very important. Among the complexity reduction techniques, the PAM decomposition approach for CPM signals have recently gained much attention, due to its effectiveness and excellent BER performance. The PAM decomposition approach decomposes CPM signals into a set of PAM waveforms and employs only significant part of the PAM waveforms to design receiver. More recently, a PAM waveforms reduction method for a special class of CPM signals, which have the so-called separable phase property, enables the CPM to be reformulated as an correlatively encoded equivalent CPM scheme, such that the equivalent CPM can be represented as less PAM waveforms than the original CPM. Nevertheless, most of the known CPM family does not satisfy the separable phase property. This paper proposes a new class of CPM with phase separable property. It is found that the new class of CPM can reduce the number of filters to 25 percent of the MLSD receiver required. Moreover, the bandwidth and power efficiency of this new set of CPM are very close to the conventional CPM and sometimes are even better.