Preamble-less nondecision-aided (NDA) feedforward synchronization techniques for 16-QAM TDMA demodulators

In this paper, the performance of fully digital synchronization techniques for time-division multiple-access (TDMA) differentially encoded 16-QAM signal transmission, over cellular mobile radio channels, is considered. The preamble-less feedforward nondecision-aided (FF-NDA) synchronization techniques used for symbol timing recovery, carrier phase recovery and amplitude gain control to overcome Rayleigh fading channel impairments, are described. Novel techniques for digital amplitude gain estimation are presented. The performance of the synchronization parameters´ estimators at the receiver is evaluated by computer simulation over additive white Gaussian noise (AWGN) and slow Rayleigh fading environment. Statistical properties of the algorithms developed are evaluated in terms of the bias and variance of the estimated errors and are compared to the Cramer-Rao lower bound