A simple coherent GMSK demodulator

We show that a symbol-by-symbol detector is the optimal MLSE demodulator for Gaussian minimum-shift keying (GMSK) (BT=0.3) on both AWGN and a class of weakly dispersive multipath fading channels. Furthermore, it is shown that, for the remaining weakly dispersive channels, a 2 state Viterbi equalizer is optimum. As an illustration of the importance of this result, a receiver is proposed which can reduce the power consumption of GSM handsets using conditional equalization, as more than 70% of the time the channel is considered to be weakly dispersive.