Doppler shift robust receiver for mobile satellite communications

We propose an open-loop receiver performing simultaneous carrier phase estimation and symbol detection in Gaussian channels affected by large Doppler frequency shifts. The structure comprises a bank of nonlinear filters (one per digital symbol) that estimate the random component of the carrier phase, coupled with a Kalman-Bucy filter that estimates the Doppler shift, and a maximum likelihood decision algorithm. The receiver's robustness allows to withstand large oscillator phase instabilities as well as significant carrier frequency offsets that characterize the communications with nonstationary satellites. Simulations performed with a binary digital phase modulation exhibit small frequency acquisition intervals which are essential in burst transmissions.