Development and application of M-ary Gaussian minimum phase shift keying modulation

GMSK's narrow spectrum and constant envelope account for its widespread acceptance in the cellular market. However, the current GMSK modulation exhibits two major flaws: (1) the ISI associated with GMSK's multiple-symbol pulse shape necessitates complex processing at the receiver; and, (2) the lack of a higher-order version of GMSK precludes incorporation of bandwidth-efficient coding to enhance link quality. This paper describes a technique used to improve BER performance of GMSK on fading and non-fading channels, and realize high-order GMSK. The availability of high-order GMSK enables the combination of constant-envelope modulation with trellis-coded modulation schemes specifically designed to operate on fading channels.