Equalization of π/4 offset DQPSK transmitted over flat fading channels

The authors propose an algorithm for an equalizer/demodulator to minimize the effects of the propagation channel on π/4 offset differential quadrature phase shift keying (DQPSK) modulated symbols transmitted over a flat fading channel. The proposed equalizer/demodulator takes as input the in-phase and quadrature samples of the received signal and outputs the corresponding decoded bits. The equalizer uses a Hilbert transform to estimate the absolute value of the phase differential of the carrier from the envelope of the carrier. This is demonstrated on a mobile radio channel