The Specification and Design of Bandlimited Digital Radio Systems

This paper presents an introductory discussion of the factors related to specification and design of bandlimited digital transmission systems. Two classes of band limited signaling pulses are considered: raised cosine and partial response. These signaling pulses are generated by using pulse shaping filters on the output of conventional QPSK, MSK, or QASK modulators. Realization of bandwidth efficient digital transmission systems is reduced to a problem of designing a special class of filters. Performance evaluation indicates information densities of up to 4.2 bits/s/ Hz can be achieved with theoretically no impairment in error performance as compared to the ideal nonbandlimited channel. Computer-aided design methods for realization of the necessary pulse shaping filters are described.