Studies on Cooperative Communications with Multiple Antennas

[[abstract]]在合作式通訊(Cooperaive Communication)中，若中繼端具有判斷解調正確與否的能力，解調後轉傳(Decode-and-Forward) 協定可以使傳輸系統擁有良好之錯誤率；反之，則可以使用放大後轉傳 (Amplify-and-Forward) 協定。在本篇論文第一部分中，我們考慮在一個在傳送端、中繼端及目的端具有1根天線的合作式通訊系統下，加入一種新型的混合型(Hybrid DF/AF)協定，並假設在中上衰退通道(Nakagami-m Fading channel)中傳送，且假設所有通道間皆不具有相關性，在M-PSK和M-QAM兩種調變下，推導出精確符元錯誤率(Exact Symbol Error Rate)，從分析結果可以看出混合型協定的效能增益。在第二部分中，我們考慮在一個多輸入多輸出的合作式通訊系統下，並假設在雷利衰減通道(Rayleigh Fading Channel)中，且建立在傳送端與中繼端可否去取得通道狀況資訊的前提，分別利用最大比例傳輸/合成(Maximum Ratio Transmission/Combining, MRT/MRC)與空時區塊編碼(Space-Time Block Code, STBC)技術作傳送。之後我們在兩種設定下，推導出精確符元錯誤率，且透過不同的通道增益觀察如何影響系統之效能，最後透過模擬的方法來驗證我們所推導出來的精確符元錯誤率正確無誤。[[abstract]]In cooperative communications, the decode-and-forward (DF) protocol can give promising error-rate performance provided that the relay node has the decoding capability. If not, the amplify-and-forward (AF) protocol can be used instead. In the first part of this thesis, we examine the cooperative communication system including a source node, a relay node, and a destination node, all equipped with a single antenna. A hybrid DF/AF protocol is considered. Under Nakagami-m fading channels, we derive the exact symbol error rate (SER) for both M-phase shift keying (M-PSK) and M-quadrature amplitude modulation (M-QAM). From the analytical result, we see that the hybrid scheme can further improve the error-rate performance for cooperation. In the second part, we focus on the cooperation scenario with multiple-input multiple-output (MIMO) settings. Under Rayleigh fading environments, based on whether the transmitting side has the required channel information, maximum ratio transmission/combining (MRT/MRC) and space-time block coding (STBC) techniques are pondered to be used. In these two circumstances, we derive the exact error rate as well. Besides, from the analytical result, we can have some insight into how the channel characteristics affect the error-rate performance. Finally, simulations show that the derived expressions are all correct.[[note]]碩