XPSK - A new cross-correlated phase-shift keying modulation technique

A new modulation technique, cross-correlated phase-shift keying (XPSK), has been developed for the bandwidth and power efficient digital transmission. The modulation scheme proposed here, in which a controlled amount of cross correlation is introduced between the in-phase and quadrature channels, has improved the envelope fluctuation of the IJF-OQPSK (QORC) modulation scheme from 3 dB to approximately O dB. Therefore, in nonlinear channels, the power spectrum characteristics of XPSK are better than those of IJF-OQPSK. The Pe performance degradation of the XPSK scheme is within 1.15 dB of the theoretical linear channel performance of QPSK systems. The power spectra of XPSK signal can be controlled by adjusting the amplitude parameter according to the nonlinearity of a specific system to get minimum Pe degradation.