在本節模擬中，我們在時變MIMO-OFDM 系統中在通道長度為 20 傳輸訊 號，其長度大於規格中的保護區間。由模擬結果圖 4–8 得知，我們的演算法可 以成功地在時變MIMO-OFDM 系統中解決通道過長的問題，如同時變
SISO-OFDM 系統一般，step sizeµ 的適當選用是很重要的，依不同天線的天線，
選擇適當的µ ，會讓追蹤的效果更好。
圖 4–8時變MIMO-OFDM 系統，通道長度=20，消除干擾，環形重建，通道追蹤
第 5 章 結論
在本論文中，首先介紹了MIMO-OFDM 的技術與架構，並對無線區域網路 802.11a/g 及 802.11n 之規格進一步介紹。之後便針對我們研究的兩個主題：抑制 ISI 以及通道追踨加以探討。
在ISI 方面，我們深入了解符元間干擾的成因並進一步利用決策回授的觀念 來降低系統的運算複雜度，成功地抑制了在802.11n 規格標準中之 MIMO-OFDM 系統符元間干擾的問題，另一方面，隨著傳輸速率的需求不斷提昇，我們的演算 法能解決CP 縮短所面臨的符元間干擾的問題。
在通道追蹤方面，我們利用適應性訊號處理的方法與決策回授的觀念，提出 了一新的演算法，和傳統的方法相比，我們的演算法能有效率地估出時變的通道 響應而節省成本，而另一方面，我們可以藉所估出的脈衝響應，消除符元間的干 擾(ISI)，使得本演算法在 MIMO-OFDM 系統中能有效地解決多重路徑與通道追 蹤的問題。
以上所討論為針對接收端解調時有可能遭遇到的問題提出解決的方法，此外 在OFDM 系統中之自動增益控制、相位雜訊等，皆有可能會影響載波資料解調，
因此未來的目標將朝向更完善的實際系統考量，將所有接收端設計有可能遭遇到 的問題一起合併設計，提出更完整的解決方法，並盡量降低計算複雜度，以提供 真正系統建構所需之高效能演算法。
第 6 章 參考文獻
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