在任何無線通道傳輸中，接收端除了會接收到含有雜訊的訊息外，傳送的過程中還會遇到路徑喪失、重路徑干擾和衰減效應的影響，而衰減程度大小與所在的環境有關。為提升傳輸的速度，藉由架設中繼站來合作協助覆蓋範圍所有的使用者，使傳送品質變好，此方法統稱合作式通訊。中繼站的加入不僅有效增加空間多樣性，設立的成本也比較低。中繼站的協定主要有放大後傳輸以及解碼後傳輸。本論文將探討在不同的中繼協定中，不同協定的效能比較以及利用不同的多樣性結合方式(例如: Selection Combining , Maximum Combing , Equal Gain Combining)在目的端利用通道資訊進行多樣性的結合並解碼，也另外提出類似典型結合的演算法。
在傳統的合作式通訊系統下，每個端點只配有獨立的天線。為了更增加空間多樣性，在各個端點上再多增加一支天線，使端點間的通訊成為一個多輸入多輸出的系統。藉由 Zero-Forcing 與 Minimum Mean-Square Error 方式來在合作式通訊系統下增加空間多樣性。為了一步改善錯誤率，另外採用時空編碼技術，從模擬結果看來，採用後能夠明顯的改善錯誤率表現。

In the wireless communication transmission, the receiver not only receives the signal with noise, but also suffers from path loss, multipath interference, and fading effect during transmission. Different kinds of situation may cause distinct distortion of signals. To reduce the probability of decoding incorrectly in the receiver, we can let the relay station help all other users for the transmission and obtain better communication quality. This is well-known as the cooperative communication.
One advantage of setting the relay station is its low complexity and cost if the relay user is idle. Another benefit is that it increases the spatial diversity. In this thesis, we will study on the performance of decode and forward (DF) and amplify and forward (AF) relaying protocols. We use different combining techniques with channel state information at the destination receiver like Selection Combining (SC) and Maximum Ratio Combining (MRC) and Equal Gain Combining (EGC) and other combining methods.
The traditional cooperative communication is equipped single antenna on each node. In this thesis, we adopt two antennas on each node and propose multiple-input multiple-output (MIMO) methods like Zero-forcing (ZF) , Minimum Mean-Square Error (MMSE) and Maximum Likelihood (ML) algorithms and combine the signals from source and relay using the EGC. In order to improve the bit-error rate performance, Space-Time Block Coding (STBC) is an efficient method to ameliorate the bit-error rate performance greatly.

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