On the elegibilty grounds of CP-QFSK for mobile radio systems

In this paper we review a class of the Continuous Phase modulation (CPM), namely, the Quaternary Frequency Shift Keying (CP-QFSK) signaling and investigate its suitability for the application in mobile radio systems. This type of modulation renders its self as a spectrally efficient scheme that is currently used in a wide variety of applications ranging from communications systems to sonar, geophysics, and biomedicine, etc. It is exhibited herein that this scheme outperforms its MSK and QPSK counterparts in terms of bandwidth occupancy due to its spectral containment. An extensive survey of research material is provided and some of the CP-QFSK system applications in various realms are highlighted. It is concluded that this signaling scheme due to its spectral efficiency is a viable and promising modulation scheme particularly in the multichannel systems of communications.