Methods of Time Offset Estimation and Performance Evaluation of Synchronization for 3GPP LTE Downlink

The long term evolution of evolved universal mobile telecommunications system terrestrial radio access, is based on OFDM techniques owing to its inherent flexibility and attractive implementation potential. This paper addresses the issue of time synchronization which is imposed severely challenges particularly in the downlink of LTE systems and the means of time offset estimation exploring different cell-specific reference signal sequences including of primary or secondary synchronization or the joint of the two different synchronization and alternatively, pilot sequence as well. Specifically, we present a comprehensive theoretical analysis of the principal of all the four methods for the realization of the estimation of the time offset. The performances of these techniques are also assessed and compared, via extensive simulations, in terms of Minimum Square Error (MSE) under various channel models. Computer simulation results are given to show that estimation of time offset using pilot signals outperforms the other three estimation methods in the whole SNR range. Moreover, there is no significant impact on primary and secondary signal regardless of channel models.