Timing Synchronization for Interleaved OFDMA Uplink System

This paper presents a symbol timing synchronization method for interleaved OFDMA uplink system in broadband multipath Rayleigh channel. The proposed timing synchronization method contains two steps: coarse and fine time synchronization. The coarse time synchronization is desired to locate the strongest path while the fine time synchronization is desired to locate the first path and both of the coarse and fine time synchronizations are performed in time domain. Two OFDM symbols are designed for timing synchronization, of which the first is for coarse time synchronization and the second is for fine time synchronization. The user specific pilot signals are constructed in the whole obtained system band in the coarse timing preamble while the user exclusive subcarrier set in the fine timing preamble. In fine time synchronization scheme, for the user specific pilot signals are constructed in different subchannels, they have special ideal autocorrelation and cross-correlation properties, which can well suppress the multi-user interferences. Simulations have been performed in MATRICE channel C, which demonstrate that the proposed timing synchronization method can work well in interleaved OFDMA uplink system. And the proposed timing estimator is also robust in frequency asynchronous environment