在當代的通訊系統中，訊號之間的傳遞都是透過無線通道傳輸，接收端除了會接收到傳輸而來的信號，還會受到雜訊的干擾，傳輸過程中也會受到路徑衰退、多重路徑干擾的影響，進而造成接收到的訊號品質不良，使錯誤率提升。為了提高接收端的信號品質，本論文採用了合作式通訊系統，該系統藉由建立多個中繼站來協助訊號做轉傳，而透過中繼站轉傳給接收端的多個信號，加以彌補端到端傳輸受到的通道衰退與雜訊干擾的影響。
中繼端的傳輸協定主要分為解碼後傳輸(Decode and Froward)與放大後傳輸(Amplify and Froward)，而在接收端採用的訊號合併技術則採用選擇合併(Selection Combing)和最大比率合併(Maximum Ratio Combing)，利用通道資訊來對接收到的多個訊號做不同的處理。
近年的無線通信發展中，多天線輸出輸入(MIMO)的系統已逐漸被普遍的電信業者所採用，因此逐漸成為不可或缺的關鍵技術。在合作式通訊系統中應用MIMO技術，能夠進一步提高無線通信系統的抗多路徑衰退和覆蓋範圍。本論文將會著重於在發射端使用傳送天線選擇(Transmit Antenna Selection)和最大比例傳送(Maximal Ratio Transmission)技術，傳統的解調方法是使用最小平方誤差(Minimum Mean Square Error)進行解調，在本文中將會探討新的解調方法，能有效降低解調時的複雜度。

In contemporary communication systems, signals are transmitted through wireless channels. In addition to receiving the transmitted signals, the receiver will also be disturbed by noise. During the transmission process, it will be affected by multi-path fading and interference, which will result in poor quality of the received signal and increase the error rate. In order to improve the quality of the received signal, a cooperative communication system is adopted in this paper.

In the development of wireless communication in recent years, the multi-antenna-input multi-antenna-output (MIMO) system has been gradually adopted, and thus has gradually become an indispensable key technology. The application of the MIMO technology in the cooperative communication system can further improve the performance. This thesis will focus on the use of transmit antenna selection (TAS) and beamforming techniques at the transmitter. The traditional demodulation method is to use minimum mean square error (MMSE) for demodulation. In this thesis, new demodulation methods will be discussed, It can effectively reduce the complexity of demodulation.

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