Performance of GMSK and comparisons with the modulation methods of the 12PM3 class

This paper shows that GMSK (Gaussian-filtered Minimum Shift Keying) modulation can be included in the 12PM3 (12-state Phase Modulation with correlation over 3 consecutive bits of the input stream) class, and compares its performance with that of other narrowband digital continuous-phase modulations. Performance comparisons are presented with reference to both AWGN channels, cochannel and adjacent channel interferences and the typical propagation conditions envisaged for SCPC/FDMA digital land mobile radio systems in urban environment. Two different receivers, coherent and frequency discrimination detection, have been considered. The sensitivity to channel distortions due to multipath propagation has been assessed by computing signature curves.