The authors consider a satellite-based mobile communication scheme based on continuous-phase modulated (CPM) signals used in conjunction with trellis-coded modulation (TCM). This scheme provides a power saving due to the coding gain of TCM, and simultaneously a reduced bandwidth occupancy due to the particular structure of CPM signals. Moreover, CPM provides constant-envelope signals, which is a requirement for satellite transponders operating in a time-division multiple-access mode. To keep the complexity manageable, a detection scheme based on differential detection of CPM is used. They describe the system and its performance, and then they investigate how to estimate the frequency shift induced in the received signal by the Doppler effect.
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