由於無線通訊系統一直朝著高速傳輸與高可靠度這兩個方向發展，多輸入多輸出系統已經成為相當重要的技術之一。
多輸入多輸出系統中較常見的技術大致上有空間多工與傳輸分集兩種，分別提供了多工增益與分集增益。
現今對於無線通訊品質的要求也愈來愈高的環境，為能兼得多輸入多輸出系統之分集增益與高傳輸速率兩項優點，
因此結合空間-時間區塊碼與空間多工之多輸入多輸出的系統被提出來，其目的為能同時獲得高分集增益與高傳輸速率。
亦同時引起許多研究學者的興趣，針對此系統而設計的接收器也陸續被提出。此些接收器雖能提供不錯的效能，
但仍存在著多重存取干擾的情形。

基於軟式決策比硬式決策可更進一步提昇偵測效能，
於本論文中，我們在結合空間-時間區塊碼與空間多工之多輸入多輸出系統下利用高效能之軟性決策資訊協助的訊號偵測器解調，
提出了兩級式軟性決策廣義旁瓣消除器，其中第一級為廣義旁瓣消除器解出各傳送訊號之初始值，
於第二級中作干擾消除之動作且該接收器加入軟性決策因子，以加強訊號偵測之用。該接收器提供了優異的效能，
但其計算複雜度偏高，因此我們又提出了一個兩級式低複雜度軟性決策廣義旁瓣消除器，該方法亦是採用兩級式作法，
於第一級之廣義旁瓣消除器中加入軟性決策，而第二級採用軟性決策匹配濾波器，使其複雜度降低。最後，我們對發展之演算法，
進行電腦模擬與效能分析，而實驗結果也驗証了本文所提之偵測器，相較於之前的方法確實能得到更好的系統性能。

With the growing demand for high transmission data rates and communication link quality,
Multiple-input multiple output (MIMO) systems, which deploy multiple antennas at both transmitter and receiver,
have been regarded as a promise for next generation wireless communication standards.
Two most popular technologies employed by MIMO systems include spatial multiplexing (SM) and space-time block codes (STBC).
The multiple access interference, however, is one of the biggest impediments to the communication quality of MIMO systems.
To alleviate this setback, a flurry a research has been conducted to devise effective receivers.

This thesis presents a novel space-time receiver with the assistance of soft information for the Alamouti STBC and SM combined systems,
which possesses the advantages of both high diversity gain and high data rates.
To effectively combat the interference,
a two-stage soft generalized sidelobe canceller (GSC)-based detector which uses the soft information to enhance the interference cancellation capability.
The first stage of the receiver provides an initial estimate of the transmitted symbols,
whereas at the second stage the soft GSC-based detectors successively refine the estimates of interference group by group
with the assistance of the information in the symbol detection process. To alleviate the computational overhead,
we also address another receiver,
which uses the a set of soft GSC in the first stage so as to provide a more precise initial estimates of the transmitted symbols,
and then uses the matched filters (MF) to estimate the interference in the second stage to lower the computational load.
Conducted simulations show that both of the developed detectors can provide superior performance compared with pervious works.
The second receiver can greatly reduce the complexity with slight performance degradation.

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