合作式通訊技術為近年來無線通訊領域增強訊號之可靠度、達到系統空間多樣性的一項有效技術。在合作式通訊架構中，來源端之訊息可藉由中繼端轉傳至目的端，使目的端擁有來至不同傳輸路徑之訊息，以獲得空間多樣性來改善系統之效能。
本文提出了多傳送對合作式通訊系統及廣播型合作式通訊系統兩種架構，於中繼端加入篩選機制，未被篩除之訊息再進行解碼後傳送，中繼端將只傳送高可靠度的訊息，藉此避免錯誤蔓延的現象；目的端則使用線性加權結合，使目的端做出最正確的決策。在考慮所提出機制下我們推導了多傳收對合作式通訊系統及廣播型合作式通訊系統的瞬時位元錯誤率公式，在已知通道狀態資訊前提下，可計算出最佳的篩除門檻及合成權重參數，促使位元錯誤率更低。藉由多傳收對合作式通訊系統位元錯誤率公式，我們可透過計算的方式快速找到多傳收對合作式通訊系統中來源端群與中繼端群的最佳配對; 而在廣播式合作式通訊系統中，則利用廣播型合作式通訊系統位元錯誤率公式，快速計算得到位元錯誤率並以其為指標來排除較差的中繼端，選擇最佳的中繼端來幫忙廣播訊息，得到最佳的位元錯誤率。由模擬結果可知，本文所提機制於多傳收對合作式通訊系統及廣播型通訊系統等不同場景架構下，理論分析得到的錯誤率與模擬結果皆相當吻合，且有最佳的系統效能。

Cooperative communication is an effective technique recently proposed to enhance signal reliability and get spatial diversity in the field of wireless communications. In a cooperative wireless communication system, the source node broadcast data to the relay node and destination node. Then the relay forwards the received signal to the destination. This transmission technology can reduce the probability of missing data.
In the proposed schemes,first the relay checks the reliability of the received signal. Then it relays the data bit to the destination only if the reliability is high enough. Otherwise, the data bits is censored. We use the linear weight combining in the destination node to make decision for received signals. We assume that channel information is perfectly known. Then, we derive the closed-form BER(bit error rate) expression for cooperative networks with multiple source-destination pairs and cooperative multicast systems. Using the closed-form BER expression, the optimal censoring threshold, combining weight and relays assignment can be found. Simulation results match theoretical values closely. Our system has better BER performance than existing technologies found in the literature .

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