空間調變是一種多天線技術，一次只會使用一根天線傳送訊號，而傳送天線的索引可以用來攜帶額外的資料。因為它能讓下世代行動通訊在減少射頻電路和功率消耗方面有一些彈性和折衷，所以近年來有很多人研究。其中，使用相差編碼的空間調變可以避免傳送前導訊號所造成的頻寬浪費，引起了不少人的興趣，目前的研究還方興未艾。然而，相差空間調變被視為原本相差空時調變的特例，而在傳送端做矩陣乘法，在接收端測試每個可能的資料空時矩陣，所以當傳送天線數目多時，複雜度會太高到窒礙難行。另外，相差空間調變所使用的複數資料空時矩陣是隨機搜尋而得，做完相差編碼後的傳送訊號有近乎無窮多可能，導致複雜度增加。在本計畫，我們將設計低複雜度的相差空間調變。本計畫的原創性之一為非矩陣乘法之相差空間調變，它將天線順序和PSK訊號兩者的相差編碼分開處理，大幅降低了複雜度，卻仍等效於原本的相差空間調變。本計畫的另一個創新性為複數資料空時矩陣的設計，使其傳送訊號是MPSK訊號而還有最佳編碼增益。我們將對所提的作法，提供數式推導及證明。 ;Spatial modulation (SM) is a multi-antenna technique which uses single transmitter antenna each time. SM can transmit additional data bits by selecting indexes of antennas. Because SM offers flexibility in reducing RF circuits and power consumption for next-generation wireless communications, it attracts much attention in recent years. Differential SM (DSM) which avoids the rate loss due to pilot is still a hot topic now. However, DSM is considered as a special case of differential space-time modulation which performs matrix multiplication at the transmitter and tests possible data space-time matrix one by one at the receiver. Therefore, the complexity is too high to be realized in the cases of a lot of transmitter antennas. In addition, the complex data space-time matrix of DSM is obtained by random searches, and there are unlimited possibilities of transmitted signal after differential encoding. This phenomenon increases the complexity as well.In this project, we aim at designing low-complexity DSM. One novelty of this project is DSM without matrix multiplication, which differentially encodes the antennas order and PSK signals separately. It decreases the complexity significantly and is still equivalent to the original DSM. The other novelty of this project is the complex data space-time matrix design, for which the transmitted signal is MPSK signal and the coding gain is maximized. We will derive and prove the proposed DSM and matrix.
