Abstract
In recent years, orthogonal frequency division multiplexing (OFDM) has been applied extensively to digital transmission, such as wireless local area networks and digital video/audio broadcasting systems. Moreover, it has been regarded as a promising transmission technique for fourth-generation wireless mobile communications. OFDM has high data rate transmission capability with high bandwidth efficiency due to its parallel orthogonal subcarriers. It is also robust against the multipath delay spread because of the cyclic extension in the time domain.In the thesis, we design a new pilot OFDM symbol suitable for use in both synchronization and channel estimation. Based on the new pilot OFDM symbol, we propose a new synchronization method that consists of a frequency offset estimation scheme and a fine frame synchronization scheme assisted by the estimated frequency responses on some subcarriers and a predefined synchronization pilot tone. Two complexity reduction methods are also introduced to show that the proposed scheme not only provides satisfactory performance under wireless environments but also has acceptable complexity for implementation. We further propose a discrete Fourier transform based channel estimator combined with an average in frequency (AIF) technique, where the samples used for AIF is adjusted by an estimated signal-to-noise-ratio to ensure the accuracy of channel estimation. Finally, a joint synchronization and channel estimation scheme along with some simulation results are given to demonstrate the usefulness and effectiveness of the proposed approaches.