| Summary: | 碩士 === 國立交通大學 === 電子工程系所 === 95 === Orthogonal Frequency Division Multiplexing (OFDM) is a popular technique in modern wireless communications. There are many systems adopting the OFDM technique, such as IEEE 802.11 a/g/n, IEEE 802.16, IEEE 802.20, and Digital Video Broadcasting, etc. On the other hand, mobility is an important issue that needs to be taken into account in the design of future wireless communication systems. For example, IEEE 802.16-2005 supports vehicle speed up to 120 km/hr, and IEEE 802.20 supports vehicle speed up to 250 km/hr, causing the channel seen by the receiver time-varying. Some channel estimators use a large number of pilot symbols to estimate the channel parameters, or use buffer to obtain desired channel parameters. In this thesis, we show two channel estimation approaches, namely the decision directed based and expectation maximization based approaches that can track the time-varying channel vectors with less insertion of pilot symbols. Finally, we evaluate the performance of the proposed systems under mobility using IEEE 802.16-2005 standard and confirm that it achieves good SER performance.
|
|---|
