| Summary: | 碩士 === 國立交通大學 === 電信工程系所 === 92 === Orthogonal frequency division multiplexing (OFDM) is a high spectral efficiency modulation technique that can successfully alleviate multipath fading effects. Digital video broadcasting (DVB) systems incorporating the OFDM technique, which can promise robustness against intersymbol interference (ISI) and efficiency in spectrum utilization, are attracting researchers and industry attention to its design and implementation. In this thesis, an OFDM-based DVB receiver with diversity reception and phase noise compensation schemes is proposed, which provides diversity gain and phase noise suppression simultaneously. Performance of a mobile communication system is typically significantly degraded due to time-varying fading channels. To mitigate this problem, diversity reception schemes at different stages of the receiver are designed to alleviate the fading effects. On the other hand, to alleviate the phase noise effect over space-time-frequency wireless channels, we propose a space-time-frequency decision feedback algorithm for phase noise compensation, in which the optimum data sample size is selected based on the high correlation between adjacent data tones. Batches of the data samples are then processed with the minimum mean square error (MMSE) criterion to obtain the optimum weights at the corresponding data tones. The batch processing can achieve a good balance between channel variation and phase noise compensation. Finally, we evaluate the performance of the proposed system and confirm that it works well in a typical urban environment.
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