REDUCTION OF ERROR FLOOR OF DIFFERENTIAL PSK IN MOBILE RADIO CHANNELSBY ADAPTIVE SAMPLING

We investigate the error floor of both differential BPSK and different ial pi/4-QPSK with adaptive sampling in two-delay fading channels wher e the excess delay is smaller than a bit length. For ''basic'' DBPSK ( i.e., using rectangular pulseshape), the error floor can be eliminated completely, but has finite values for pulses with raised-cosine spect rum. For pi/4 DQPSK, the error door is reduced by only a factor on the order of two as compared to fixed sampling.