空間調變(Spatial Modulation)是近年來逐步發展起來的一種多輸入多輸出(Multiple-Input Multiple-Output, MIMO)技術，使得天線索引成為一種額外攜帶的資料位元，以提高整體頻譜效率。空間調變不僅能夠簡化多天線結構，降低成本，還能滿足無線通訊系統多樣化的鏈路配置要求，充分利用通道資源，實現高速可靠的傳輸。
隨著時間的推移，為了更進一步的提高頻譜效率(Spectral Efficiency, SE)以及位元錯誤率(Bit Error Rate, BER)的表現，學者們陸續提出了比原本空間調變更優秀的技術，例如，正交空間調變、改進的正交調變、符號正交調變…等。且某些空間調變技術除了能提高頻譜效率外，還不需額外提高射頻鏈的成本。
然而早在20世紀90年代，Alamouti發表了一篇在通訊領域影響甚大的論文，文中提出了一種高效率且實用的空間分級技術，稱為空時區塊編碼(Space Time Block Code, STBC)，由於STBC具有簡單的結構和良好的分集增益，已廣泛運用於4G通訊系統，因此，還有學者將其與正交空間調變做結合，以此得到更好的表現，並稱之為空時正交空間調變(Space Time Quadrature Spatial Modulation)。
本論文基於以上背景，先是改良了原本的空時正交空間調變，並提出了空時改善正交空間調變(ST-IQSM)以及空時符號正交空間調變(ST-SQSM)。本論文會從頻譜效率和位元錯誤率兩個方面去分析，並考量傳送天線組數的設計對於性能的影響，並且綜合現已提出的調變方式做一系列的討論分析。

Spatial Modulation is a Multiple-Input Multiple-Output (MIMO) technology that has been gradually developed in recent years. It makes the antenna index an additional data bit to improve the overall spectrum efficiency. Spatial modulation can not only simplify the multi-antenna structure and reduce costs, but also meet the diversified link configuration requirements of wireless communication systems, make full use of channel resources, achieve high-speed and reliable transmission.
Over time, in order to further improve the performance of spectral efficiency (SE) and bit error rate (BER), scholars have successively proposed better technologies than the original spatial tone change. For example, Quadrature Spatial Modulation, Improved Quadrature Spatial Modulation, Signed Quadrature Spatial Modulation...etc. In addition, some spatial modulation techniques can improve spectral efficiency without increasing the cost of rf chain.
However, as early as the 1990s, Alamouti published a paper that had a great impact on the field of communications. The paper proposed a highly efficient and practical space classification technology called Space-Time Block Code (STBC). Because STBC has a simple structure and good diversity gain, it has been widely used in 4G communication systems. Therefore, some scholars combine it with orthogonal spatial modulation to obtain better performance and call it Space-Time Quadrature Spatial Modulation (ST-QSM).
Based on the above background, this paper first improved the original space-time Quadrature Spatial Modulation, and proposed Space-Time Improved Quadrature Spatial Modulation (ST-IQSM) and Space-Time Signed Quadrature Spatial Modulation (ST-SQSM). This paper will analyze the spectrum efficiency and bit error rate, and consider the effect of the number of antenna groups on the performance, and will do a series of discussions and analyses based on the proposed modulation methods.

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