Fixed reference shift keying modulation for mobile radio transmission in a fading channel environment

A modulation/demodulation technique that provides a substantial performance improvement in phase and amplitude distorted channels typically encountered by moving vehicles receiving radio signals is presented. This technique, referred to as fixed reference shift keying, uses a pilot reference signal within the coherence bandwidth of the channel and instantaneous phase estimation techniques at the receiver. Signal estimation is performed using the difference in instantaneous phase estimates of the pilot and carrier received waveforms. This relative phase measurement ensures a degree of immunity to the phase distortion introduced by the channel, permitting a marked improvement in performance.<>