Gmsk Frequency Detection using Decision Feedback Equalisation

Frequency detection of GMSK signals using one-bit decision feedback equalisation (DFE) in conjunction with offset decision instant is presented. Experiments on a 16kbit/GMSK signal reception with a premodulation filter bandwidth-bit duration product (Bb T) of 0.25 (typical for mobile radio applications) show that, compared to MSK signal reception, a bit error rate (BER) of 10-2 is obtained with a loss of about 4dB in the signal energy per bit/noise power density ratio (Eb/N0) in the additive white Gaussian noise (AWGN) channels. In the cochannel interference limited channels, a BER of 10-2 is obtainable at a signal/interference power ratio (SIR) about 5.5 dB larger than in the case of MSK signal reception.