本論文將針對IEEE 802.16－2004的下行系統中頻率同步（Frequency Synchronization）的問題加以探討，由於頻率偏移（Frequency Offset）會造成次載波（Sub－Carrier）之間的干擾，進而造成系統整體的效能嚴重衰減。為了降低這個效應，我們在此使用四種演算法來估測頻率偏移量，並且觀察這四種演算法分別在浮點數（Floating-Point）及定點數（Fixed-Point）下的效能，並且做比較。最後，使用疊代（Iterative）的方式改善其中一種演算法的效能。 The thesis takes a discussion on the issue of frequency synchronization of downlink system in IEEE 802.16-2004 standard. Frequency offset causes interference between sub-carriers such that the performance of the entire system attenuates greatly. In order to degrade the effect, here we estimate frequency offset by four different algorithms. For each algorithm, we observe the performance under floating point and fixed point cases respectively and make comparison between them. Finally, performance improvement applied by one of the four algorithms is achieved by iterative method.
