Low-Complexity Detection of Binary CPM With Small Modulation Index

Binary continuous phase modulation (CPM) with modulation index h = 0.5 can be approximated by a linear modulation, which leads to a low-complexity serial receiver. By reconstructing CPM signals generated with a small modulation index into equivalent CPM signals with modulation index h = 0.5, a low-complexity detector (LCD) for binary CPM with small modulation index is proposed. The complexity of the resulting detector is significantly reduced with respect to that of optimal coherent receivers with negligible performance loss. In addition, the detector can generate appropriate metrics for the soft decision decoding, which is desirable in a coded CPM system.