Symbol Timing Detection for OFDM Signals with Time Varying Gain

The packet based OFDM (Orthogonal Frequency Division Multiplexing) systems require the fast timing synchronization using a preamble located at the beginning of the received data frame. To detect the symbol timing of the received signal, periodicity of the preamble can be utilized. However, the time varying gain of preamble sample values can affect the performance of the synchronization in case the samples of the beginning part of the packet are involved. This is due to the AGC (Automatic Gain Control) operation at the receiver. Conventional symbol timing detectors use the very last part of the short preamble whose gain level is settled upon the completion of the AGC operation. In this paper the symbol timing detector is proposed using all parts of the short preamble to improve the detection performance keeping the independence of the AGC gain. Simulation results show that the proposed method shows compatible performance for various channel environments.