| Due to its high band-width efficiency, its robustness to multipath and pulse, its high transmission speed and its ability of flexible modulation on subcarriers in accordance with the channel conditions, Orthogonal Frequency Division Multiplexing (OFDM) has found its wide application in high speed data transmission wireless systems, such as digital video broadcast, digital television, wireless local area network and will pay a key role in the forth generation mobile communication systems. One of the main defects of OFDM system is sensitive to synchronization errors. Therefore, it must be good theoretical and practical value to research on synchronization algorithm.We systematically analyzed the affect of frame synchronization errors to the OFDM system and frame timing synchronization algorithm suitable for IEEE802.11a, and a modified method of frame timing estimation which is suit to IEEE802.11a is proposed. This paper aimed at the low precision of original frame timing synchronization in low Signal-to-Noise condition, and a modified method of frame timing estimation is proposed. This algorithm bases on the correlation technique with a threshold comparison mechanism and takes advantage of the cross-correlation of short preamble. Although the improved frame timing synchronization algorithm brings more calculation, it has characters of exact symbol timing, simple in structure. The algorithm enhances the performance, it is suit for application. |
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