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。
在本論文中，提出了三個相差空間調變的改良設計，一個是增加速率的相差空間調變，透過每兩個區塊間多傳一個資料位元的方式。另一個是增加多樣性的相差空間調變，在論文[4]中是使用重複符元的方式，在本篇論文我們提出了不同的方法來增加它的多樣性，通過適當的設計區塊碼和複數天線索引矩陣，可以實現我們所期望的傳送多樣性，和論文[4]的方法相比，我們的碼字有著更高傳輸速率。最後一種為將論文[32]籬柵編碼方法應用在傳送多樣性等於天線數量的相差空間調變，在傳送矩陣方面，分為一般的正交矩陣和超級正交矩陣，在傳輸速率相同的情況下，論文[32]的方法有著更好的錯誤效能。

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.
In this paper, we propose three improved designs of DSM. One is increased-rate DSM by transmitting one additional data bit per two blocks. Another is increased-diversity DSM. To increase diversity, DSM using repeated symbols was proposed in [4]. In this paper, we propose a different approach to increase diversity of DSM. By properly designing block coded modulation and complex antenna-index matrices, the desired diversity order can be achieved. Compared with the existing schemes with the same diversity, our codes achieve higher transmission rates. The other is to apply the trellis-coded method to the full-diversity DSM. In terms of the transmission matrix, it is divided into a general orthogonal matrix and a super-orthogonal matrix. The method of [32] has better error performance when the transmission rate is the same.

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