Cooperative communications: Synchronization in fast flat-fading channels with various signal constellations

A non-data-aided near maximum likelihood (NDA-NML) symbol timing estimator is applied to cooperative communications in fast flat-fading conditions. The performance of a three-node detect-and-forward cooperative communication system is evaluated operating in fast Rayleigh fading channels using various signal constellations with and without synchronization. Timing errors have significant effect on performance. The lower complexity NDA-NML estimator performs well for larger signal constellations in fast fading, when compared to a data aided maximum likelihood (DA-ML) estimator.