M-ary phase position shift keying with orthogonal signalling

An improved M-ary phase position shift keying (MPPSK) modulation, aiming to increase the spectral and energy efficiencies of existing MPPSK schemes while preserving their low demodulation complexity and error performance, is proposed in this study. Specifically, an improved MPPSK with orthogonal signals called OI-MPPSK is presented. For the proposed OI-MPPSK, the authors develop two demodulation schemes that employ a special impact filter (SIF): (i) the orthogonal SIF correlator (OSC) scheme, which consists of the orthogonal transmission, the SIF and a correlator; (ii) the orthogonal SIF position (OSP) scheme, which is the same as the OSC scheme except that the coherent demodulator is replaced by exploiting position-related information. As a result of exploiting the position-related information in the proposed OI-MPPSK scheme, the SER performance of the OSP-based demodulator is superior to that of the OSC-based demodulator.