相差空間調變是一種一次只使用一根天線傳送訊號的多天線技術，藉由選擇傳送天線可以多傳額外的資料位元，並避免前導(pilot)訊號的浪費。傳統相差空間調變極其複雜，本論文的目標是降低相差空間調變的複雜度。在傳統相差空間調變中，非同調最大可能性檢測的複雜度和傳送天線的數量成指數關係，在本論文中，提出一種新的非同調最大可能性檢測，其複雜度大致是和傳送天線數量成正比。另一方面，由於現有的複數值天線索引矩陣會造成傳送訊號的星座圖有極其多個訊號點，我們也提出了一個系統化複數值天線索引矩陣的設計，使傳送訊號星座圖只有少數個訊號點。而我們所提出的這兩種技術在沒有犧牲錯誤效能的情況下都減少了複雜度。 在最近一篇論文中，提出一種使用在下行大規模傳送天線系統的相差空間調變，本論文也指出它在同一根天線所連續傳送的訊號相距時間可能會太遠，導致在連續改變的衰退通道有不理想的錯誤率，因此我們提出修正的做法，並改善錯誤蔓延的問題，電腦模擬結果也顯示出在連續改變的衰退通道下，我們提出的做法有更好的錯誤效能。 ;Differential spatial modulation (DSM) is a multi-antenna technique that uses only one antenna to transmit signals at a time and avoids pilot overhead. By selecting the transmitting antenna, additional data bits can be transmitted. The conventional DSM is extremely complex. We aim to reduce the complexity of DSM in this thesis. The complexity of noncoherent maximum-likelihood (ML) detector of conventional DSM increases exponentially with the number of transmitter antennas. In this thesis, we propose a new ML detector whose complexity is roughly in proportional to the number of transmitter antennas. On the other hand, since the complex-valued antenna-index matrices causes the constellation of the transmitted signal has unlimited points, we have also proposed a systematically designed complex-valued antenna index matrices so that the transmitted signal constellation has a few signals points only. Both the proposed techniques decrease the complexity without sacrificing error performance. In a recent paper, DSM used in downlink large-scale transmission antenna systems was proposed. This thesis also points out that it may be too far away from the signal continuously transmitted by the same antenna, resulting in bad error performance for time-varying fading channels. Therefore, we propose a method which has a better error performance in time-varying fading channels.
