近年來, 合作式通訊網路引起了不少的關注, 因為合作式通訊網路增加了通訊系統的可靠性, 並且達到比較好的錯誤率表現。本篇論文主要考慮一個存在竊聽者的合作式通訊系統, 融合中心基於從中繼節點傳送來的資訊, 處理後再做出全局決策 (global decision) , 以判斷從發射端傳送來的符號位元。然而, 竊聽者也能夠竊聽到由中繼點傳給融合中心的消息, 並量化原始觀測值來推斷其結果。
　　本篇論文採用一個存在竊聽者之合作式通訊系統, 使用編碼理論的分散式接收技術。更仔細來說, 我們使用 Exhaustive Search 的方法來搜尋最佳的碼簿, 符合以竊聽者與融合中心的錯誤率之比例當作準則來最小化。我們的模擬結果, 顯示了根據我們提出的準則所獲得之最佳碼簿, 確實達到更好的系統性能。此外, 可以從執行的模擬結果觀察出用於存在竊聽者系統下之最好的碼簿結構。

Cooperative communication networks have attracted extensive attention recently, because it increases the reliability of communication systems and archives a better error rate performance. This thesis mainly considers a cooperative communication system in the presence of eavesdroppers. Based on the local summary statistics transmitted by relay nodes, the fusion center makes a global decision in favor of one of symbols sent from the source. However, the eavesdropper can also eavesdrop the information which is sent from a node to the fusion center and quantizes those raw observations to infer the information.
This thesis adopts a distributed reception technique using coding theory for cooperative communication systems in the presence of eavesdroppers. Specifically, an “Exhaustive Search” method is utilized to search the best codebook in accordance with the criterion of the minimization of the error probability ratio of the fusion center and eavesdropper. The results obtained by our simulation show that the best codebook obtained according our proposed criterion does achieve a better system performance. In addition, the best structure of the codebook used for the system in the presence of eavesdroppers can be observed from the conducted simulation results.

目錄
論文審定書　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　i
誌謝 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　ii
摘要　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　iii
Abstract　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　iv

1 序論　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　1
　1.1 介紹．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．1
　1.2 分散式接收之使用編碼的技術．．．．．．．．．．．．．．．．．．．2
　1.3 存在竊聽者的通訊網路．．．．．．．．．．．．．．．．．．．．．．2
　1.4 研究方法．．．．．．．．．．．．．．．．．．．．．．．．．．．．3
　1.5 論文架構．．．．．．．．．．．．．．．．．．．．．．．．．．．．4

2 系統模型　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　5
　2.1 系統模型．．．．．．．．．．．．．．．．．．．．．．．．．．．．5
　2.2 中繼端量化訊號並傳送到融合中心解碼．．．．．．．．．．．．．．．8

3 碼字集矩陣的設計　　　　　　　　　　　 　　　　　　　　　　　　　 　10
　3.1 無竊聽者時的碼字編碼方法．．．．．．．．．．．．．．．．．．．．10
　3.2 存在竊聽者時的碼字編碼方法．．．．．．．．．．．．．．．．．．．13

4 模擬結果和分析　　　　　　　　　　　　　　　　　　　　　　　　　 　18
　4.1 碼字集矩陣錯誤率比較．．．．．．．．．．．．．．．．．．．．．．19
　4.2 系統出現竊聽者通道．．．．．．．．．．．．．．．．．．．．．．．21
　4.3 不同多個中繼點之碼字集矩陣．．．．．．．．．．．．．．．．．．．23
　4.4 最佳碼字集矩陣之分析．．．．．．．．．．．．．．．．．．．．．．26

5 結論　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　34

參考文獻　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　35


　　　　　　　　　　　　　　　　　圖目錄
2.1.1 QPSK 星座點 ．．．．．．．．．．．．．．．．．．．．．．．．．．．6
2.1.2 系統模型圖 ．．．．．．．．．．．．．．．．．．．．．．．．．．．．7
2.2.1 碼字集矩陣編碼 ．．．．．．．．．．．．．．．．．．．．．．．．．．8
3.1.1 N = 5 , = 6 (dB) , 無竊聽者時之碼字集矩陣的錯誤率．．．．．．．．．．11
3.1.2 N = 6 , = 6 (dB) , 無竊聽者時之碼字集矩陣的錯誤率．．．．．．．．．．12
3.2.1 N = 5 , = 0 (dB) , 存在竊聽者時之碼字集矩陣的錯誤率．．．．．．．．．13
3.2.2 N = 6 , = 0 (dB) , 存在竊聽者時之碼字集矩陣的錯誤率．．．．．．．．．14
3.2.3 N = 6 , = 6 (dB) , 融合中心與竊聽端的錯誤率之比例 Re ．．．．．．．15
3.2.4 N = 6 , = −10 (dB) , 融合中心與竊聽端的錯誤率之比例 Re ．．．．．．．16
3.2.5 N = 6 , = 20 (dB) , 融合中心與竊聽端的錯誤率之比例 Re ．．．．．．．17
4.1.1 不同中繼點數系統錯誤率的比較 ．．．．．．．．．．．．．．．．．．．19
4.1.2 文獻[8][9] 與搜索碼字集矩陣的錯誤率比較 ．．．．．．．．．．．．．．20
4.2.1 6-Node , = 0 (dB)． ．．．．．．．．．．．．．．．．．．．．．．．．21
4.2.2 6-Node , = 5 (dB) ．．．．．．．．．．．．．．．．．．．．．．．．．22
4.3.1 N=5 , = 0 (dB) 搜尋的碼字編碼比較 ．．．．．．．．．．．．．．．．．23
4.3.2 N=6 , = 0 (dB) 搜尋的碼字編碼比較 ．．．．．．．．．．．．．．．．．24
4.3.3 N=6 , = 0 (dB) 不同訊雜比環境之搜尋的最佳碼字編碼比較 ．．．．．．．25
4.4.1 QPSK 星座點與碼字解碼示意圖．．．．．．．．．．．．．．．．．．．28


　　　　　　　　　　　　　　　　　表目錄
4.4.1 Fusion Center: 前半段經傳送通道後判斷的機率 ．．．．．．．．．．．．29
4.4.2 Eavesdropper: 後半段經竊聽通道後判斷的機率 ．．．．．．．．．．．．29
4.4.3 N = 6 , 碼字集矩陣(A) 星座點錯誤率與漢明距離．．．．．．．．．．．．30
4.4.4 N = 6 , 碼字集矩陣(C) 星座點錯誤率與漢明距離．．．．．．．．．．．．30
4.4.5 N = 5 , 搜索的最佳碼字集矩陣(iii) 星座點錯誤率與漢明距離．．．．．．．31
4.4.6 N = 6 , 搜索的最佳碼字集矩陣(D) 星座點錯誤率與漢明距離．．．．．．．31
4.4.7 N = 6 , 只傳送Q1 , 原碼字集矩陣與相對兩列對調之矩陣 ．．．．．．．．32
4.4.8 N = 6 , 只傳送Q1 , 相鄰兩列對調之矩陣 ．．．．．．．．．．．．．．．32
4.4.9 N = 5 , 只傳送Q1 , 原碼字集矩陣與列對調後之矩陣 ．．．．．．．．．．33
4.4.10 N = 6 , 只傳送一種訊號之不同漢明距離分配表現．．．．．．．．．．．33

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