A FULLY DIGITAL FEEDFORWARD MSK DEMODULATOR WITH JOINT FREQUENCY OFFSET AND SYMBOL TIMING ESTIMATION FOR BURST MODE MOBILE RADIO

A strictly feedfonvard demodulator structure for minimum shift keying (MSK) modulation with joint nondata-aided symbol clock and frequency o ffset estimation is presented. Due to its feedforward operation, clock synchronization and frequency offset compensation are hang-up free, a nd the demodulator is well suited for a digital implementation. The sa mpled baseband signal is passed through a nonlinearity and smoothed by a digital filter. The magnitude of the filter output directly drives the clock recovery process. The phase of the smoothed signal is an est imate of the carrier frequency offset and is used for offset compensat ion. Following synchronization, the signal is demodulated differential ly coherent. The performance of the demodulator is assessed for the AW GN and the Rayleigh flat and frequency-selective fading channel by com puter simulations.