Partial response quadrature differential phase shift keying (PR-QDPSK): spectrally efficient linear modulation for personal communications
M.R. Heath, Luis B. Lopes · Electronics Letters · 1989
A novel linear modulation technique is proposed for land mobile radio and cordless telephony applications. Excellent spectral efficiency is achieved since the transmitted signal fits entirely within a channel spacing equal to the bit rate, while yielding good performance for both coherent and non-coherent detectors.