臺灣博碩士論文加值系統

由於訊號在傳送的過程中會受到通道的破壞，因此在接收端中通道估計(channel estimation)是無線傳輸中非常重要的一環。正交分頻多工系統(Orthogonal Frequency Division Multiplexing，OFDM)對於頻率偏差(frequency Offset)非常的敏感，雖然在做完頻率估計與矯正後剩餘的頻率偏差所引起的載波間的干擾(inter carrier interference)已經很小可以忽略，但剩餘的頻率偏差卻會造成整個符元相位的旋轉，會影響到最後檢測(deceision)的結果，因此本篇論文針對這兩個部分作詳細的說明，除了演算法的介紹與電腦模擬，亦包括了硬體電路的架構實現。

This thesis is devoted to the two important functions of an orthogonally frequency division multiple (OFDM) baseband receiver: the channel estimation and phase tracking. As transmitted signal is always severely corrupted by fading channels during wireless transmission, channel estimation is essential for a baseband receiver. Because of the nature of an OFDM system, the OFDM modulated signal is sensitive to frequency errors. When the voltage control oscillators at both the transmitter and receiver sides are not stable, the received baseband signal suffers from time-varying residual frequency errors. If the frequency error is not properly compensated, it accumulates to become phase errors to the received signal. Accordingly, the OFDM baseband receiver should estimate and compensate such residual frequency error symbol-by-symbol. In addition to theoretical study of algorithms of channel estimation and phase tracking, hardware implementation using FPGA of these two functions is reported in this thesis.

1. 序論
1.1 研究動機
1.2 內容大綱
2. IEEE 802.11a實體層規範
2.1 訊框格式與相關參數
2.2 PLCP Preamble
2.3 SIGNAL field
2.4 Data field
3. OFDM系統
3.1 OFDM系統簡介
3.2 數學模型
3.3 循環置首(Cyclic Prefix)
3.4 OFDM系統優缺點比較
4. IEEE 802.11a通道等化與相位追蹤演算法
4.1 通道估計(Channel Estimation)
4.1.1 通道模型(Channel Model)
4.1.2 通道估計演算法
4.1.3 通道電腦模擬
4.2 相位追蹤(Phase Tracking)
4.2.1 剩餘頻率的產生
4.2.2 相位估計與矯正
4.2.3 相位追蹤與系統效能電腦模擬
5. 硬體電路架構
5.1 緩衝區(Buffer)與移除保護頻帶(Remove GI)
5.2 重新排序(Reorder)
5.3 通道估計(Channel Estimation)與載波相位追蹤(Phase Tracking)
5.4 Demapping與Deinterleaver
6. 模擬與量測結果
6.1 量測流程與量測環境
6.2 模擬結果與測試結果
7. 結論與未來工作方向
Reference
中英文名詞對照表

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