The use of Doppler tolerant reference signals in time synchronization applications

This paper describes a technique for achieving discrete time synchronization in systems which, in addition to additive Gaussian noise and phase offsets, regularly experience the effects of Doppler frequency shifts. The approach, based on a maximum likelihood (ML) timing estimator, utilizes certain properties of special reference waveforms to provide a simplified, but robust, estimator implementation for receivers using the reference to recover timing. The reference signal properties are characterized and subsequently used in an implementation of an ML timing estimator. Analysis and simulation results indicate that in the presence of additive noise, phase, and Doppler errors, using special (Doppler tolerant) waveforms in ML estimator structures can provide significant performance improvements avoiding the complexity of phase and frequency compensation mechanisms