基於合作式通訊系統中移除轉傳端假設之研究

Studies on The Removal of Assumption in Relay for Cooperative Communications

丁怡秀(Yi-Hsiu Ting)

指導教授 ： 李彥文

國立暨南國際大學/科技學院/通訊工程研究所/碩士(2011年)

https://doi.org/10.6837/NCNU.2011.00304

摘要

在合作式通訊系統(Cooperative Communication System )中，若轉傳端(Relay)使用解調後轉傳協定(Decode-and-Forward Protocol)，即轉傳端接收到傳送端(Source)傳來的訊號且經過解調與循環冗於檢查碼(Cyclic Redundancy Check, CRC)處理後，再決定是否要轉傳至目的端(Destination)，可使系統獲得最佳的效能。但是CRC不能完全偵測每種錯誤模式，且系統不一定具備檢查碼。因此，本論文提出在不具有CRC之合作式通訊系統架構下於轉傳端設置門檻值(Threshold Value)用來判斷訊號的正確性，並在轉傳端運用黃金比例搜尋法(Golden Selection Search, GSS)找出每刻的最佳化門檻值，透過最佳化門檻值來最低化瞬時系統錯誤率。在本論文中我們亦討論於合作式通訊系統中應用不同的訊號調變技術，且轉傳端透過最佳化方法求出適當的門檻值以提升系統效能，將此方法能更貼近現實的情況。最後，在模擬結果中也將顯示此系統效能並與其他方法做比較。

關鍵字

合作式通訊 ； 解調後轉傳 ； 門檻值 ； 最大比例合成器 ； 黃金比例搜尋法

並列摘要

In cooperative communications, if the decode-and-forward protocol (DF) is used, the relay will employ the cyclic redundancy check (CRC) code to check the correctness of its decoded result and determine to forward or not. This can achieve the best cooperation performance. However, the CRC code cannot detect all erroneous patterns or may not always exist in the system. In this thesis, for the DF cooperation without the use of CRC, we utilize a threshold-based detection in the relay to determine the correctness of the decoded result. The Golden selection search (GSS) method is used to find the optimal threshold value for minimizing the end-to-end error-rate performance. In addition, we discuss this DF scenario with different modulation schemes, and the corresponding optimal threshold values are determined as well for better performance. Our approach can then be used in more practical circumstances. Finally, simulations are performed, and different methods are compared to show the effectiveness of the proposed method.

並列關鍵字

Cooperative Communication ； Decode-and-Forward ； Threshold Value ； Maximum Ratio Combining ； Golden Selection Search

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