Reduced phase-state detection based on virtual modulation indexes for Multi-h CPM

.Simplified detection with reduced phase-state based on virtual modulation indexes was designed for Multi-h CPM.Multiple sets of modulation indexes different from the transmitter were constructed in the receiver,and the per-survivor processing was used to solve the mismatch caused by the inconsistency of the modulation indexes between the receiver and the transmitter.When the denominator of virtual modulation index was much smaller than the original denominator of actual transmitted signal,the phase states of coherent sequence detection could be effectively simplified,thus the complexity of coherent detection for Multi-h CPM could be reduced.The trellis could be simplified further via combining with the frequency pulse truncation(FPT) used for simplifying correlation states.The simulation results show that for advanced range telemetry (ARTM) CPM signal,various simplified receiving schemes based on virtual modulation indexes can be designed.When the virtual modulation indexes are set to $\left[\frac{\text{3}}{\text{4}}\text{,}\frac{\text{2}}{\text{4}}\right]$,the number of trellis states can be reduced from 512 (in optimal detection) to 64,but the performance loss is less than 0.05 dB.Further combined with FPT algorithm,the number of trellis states can be reduced to 16,while the performance loss is only 0.75 dB.