ON THE SPECTRAL EFFICIENCY OF CPM SYSTEMS OVER REAL CHANNEL IN THE PRESENCE OF ADJACENT CHANNEL AND COCHANNEL INTERFERENCE - A COMPARISON BETWEEN PARTIAL AND FULL RESPONSE SYSTEMS

In the context of research developed to define the design criteria of terrestrial or satellite digital mobile radio networks, special attention has been paid in recent years to partial-response continuous-phase modulation (CPM) systems. In this application and, more generally, in all the new radio systems to be designed—for example, local radio networks or portable communication systems—a crucial point is determination of the actual spectral efficiency obtainable. To this end, the fundamental role played by adjacent and cochannel interference must be considered. The computer program implemented allows general analysis of CPM systems with limiter-discriminator detection and symbol-by-symbol regeneration; to be precise, the combined effects of intersymbol interference, noise, and adjacent channels or cochannel interference have been tested to give the design criteria of the transmission system. To emphasize the role played by interference, an ideal multipath-free channel has been considered: so, with reference to a binary case, Gaussian minimum-shift keying (GMSK) systems have been investigated and compared with full-response CPM systems to obtain suitable tradeoff between spectral efficiency (connected to channel spacing at radiofrequency) and signal-to-noise ratio with fixed bit-error probability. The numerical results presented emphasize the performance obtainable with full-and partial-response techniques for varying system parameters such as phase deviation index, receiver filter bandwidth, and spectral efficiency. © 1990 IEEE