Optimum frame and frequency synchronization for OFDM systems

In this paper, we propose an optimum frame and carrier frequency synchronization method for a burst type orthogonal frequency division multiplexing (OFDM) application such as a wireless local area network (WLAN). In the case of burst transmission, rapid frequency synchronization is essential in order to rapidly achieve orthogonality among subcarriers. By estimating the frequency offset and timing offset before and after the demodulation we can achieve acquisition within one OFDM symbol period. Due to the subcarrier ambiguity in the maximum likelihood estimation (MLS) frequency detector before demodulation, the maximum correctable frequency range is limited to /spl plusmn/1/2 of the subcarrier spacing. This problem can be solved by using a frequency acquisition method after FFT.