正交分頻多工(Orthogonal Frequency Division Multiplexing, OFDM) 技術，已經廣泛使用於現代的無線網路實體層中，在射頻電路的架構方面，直接轉換接收機(Direct-conversion) 也越來越受到廣泛的使用，因其具備低成本與小面積等優點。伴隨著此結構容易受到射頻元件與震盪電路的誤差帶來IQ 不平衡(IQ Imbalance)、直流偏移(DC Offset) 與載波頻率偏移(Carrier Frequency Offset) 等問題，降低接收機性能。因此在本篇論文，提出了使用訓練符元以最小平方(Least square) 做參數估計，達到在無線區域 網路系統中快速同步的目的，並且較現有演算法有更好的效能。最後，基於我們的演算法提出同步電路架構，並以VHDL 撰寫RTL 驗證我們的電路結構效能。 Orthogonal Frequency Division Multiplexing (OFDM) is a widely used technique in the physical layer of modern communication system. Unfortunately,OFDM system is sensitive to imperfect synchronization and non-ideal front-end effects such as IQ Imbalance, DC Offset and carrier frequency offset, leading to serve system performance degradation. In this thesis, we consider recovering the WLAN OFDM signals in the presence of these imperfect conditions, we propose least-square (LS) equalization for Joint IQ Imbalance and carrier frequency offset estimation. From computer simulation results, the proposed algorithm has better performance than existing algorithms. Finally, the VHDL Design is used to verity the feasibility in electric circuit structure.
