On Continuous Phase Modulation in Cellular Digital Mobile Radio Systems

This paper considers a class of constant-amplitude digital modulation schemes with smoothed partial-response, continuous-phase modulation. This gives a bandwidth-efficient digital modulation scheme. With the baseband quadrature combiner described below, these modulation schemes can also be used with time-division retransmission. The concept of time-division retransmission is briefly described below. This scheme makes it possible to use simple equipment at the mobile unit, and yet use several branches of space diversity, assuring a reasonable error rate on the fading channel. Most of the signal processing and all diversity combining is performed at the base stations. To obtain good spectral efficiency in digital mobile radio systems, * Bell Laboratories. Currently at the University of Lund, Sweden. °Copyright 1983, American Telephone & Telegraph Company. Photo reproduction for noncommercial use is permitted without payment of royalty provided that each reproduction is done without alteration and that the Journal reference and copyright notice are included on the first page. The title and abstract, but no other portions, of this paper may be copied or distributed royalty free by computer-based and other information-service systems without further permission. Permission to reproduce or republish any other portion of this paper must be obtained from the Editor. 2067