在合作式正交分頻多工系統中，其中一個值得挑戰的議題為不同的傳送端會有各自的震盪器，導致接收端所收到的訊號會同時存在多個載波頻率偏移的問題。這個研究問題截至目前為止仍然無法徹底改善，即使是在不同的載波頻率偏移在接收端是已知的情況下。因此，本篇論文提出一個載波間干擾自我消除的改善方法來對抗多個載波頻率偏移所造成的影響。此種方法是將兩根天線間的傳送訊號同時擺放在互相對稱的載波上，在接收端將所接收到的訊號加以結合並進一步完成干擾自我消除。除此之外，為了提升接收訊號偶數載波跟奇數載波間的訊雜比，在接收訊號做傅利葉轉換之前，會事先將所接收到的訊號複製成兩份並補償頻率偏移校正。最後，將接收端收到的頻域訊號偶數載波跟奇數載波做最大比例結合(Maximum Ratio Combining, MRC)與解碼，並經由模擬結果將所提的改善方法與之前的定理做進一步的效能比較與分析。

One of the challenges of distributed cooperative orthogonal frequency division multiplexing systems is that the multiple carrier frequency offsets (CFOs) simultaneously present at the receiver. According to our knowledge up to now, even the CFOs are known at the receiver, the way to perfectly eliminate the effect of CFOs is still an open problem. This thesis proposes a scheme to mitigate the effect due to multiple CFOs by using the concept of intercarrier interference self-cancellation in transitional OFDM systems, a scheme where the data are simultaneously modulated on symmetric subcarriers between two transmit antennas. Before processing FFT, two values related to CFOs are used to adjust the time-domain signal resulting in better signal-to-interference ratio in even and odd subcarriers respectively. After that, the data are combined by applying maximum ratio combining and then decoded. Simulation results are given to demonstrate the effectiveness of the proposed scheme as compared to previous scheme.

論文審定書 i
誌謝 ii
中文摘要 iii
Abstract iv
Contents v
List of Figures vii
Chapter 1 Introduction 1
Chapter 2 System Model 4
2.1 OFDM System Model 4
2.2 The System Model of Distributed MISO-OFDM 8
2.3 The ICI Problem in Distributed MISO-OFDM Systems 10
Chapter 3 Literature Review 11
3.1 Correction of Carrier Frequency Offsets in Distributed MIMO Systems 11
3.2 STBC-based ICI-Self Cancellation Scheme in Distributed MISO Systems 15
Chapter 4 Proposed Coding Scheme 21
4.1 The Proposed Coding Scheme 21
4.2 The Correction of Multiple CFOs 23
Chapter 5 Simulation Results 33
Chapter 6 Conclusions 38
References 39
Abbreviations 44

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