未來的無線通訊系統必需要提供非常快速的傳輸速率以提供愈來愈多的語音及多媒體需求，直接序列分碼多工接取系統(Direct Sequence Code Division Multiple Access, DS-CDMA)目前已被採用為第三代行動通訊系統並且相較於其他傳統多工接取系統而言，直接序列分碼多工接取系統可提供更高的容量。在無線通訊中，使用多根傳送天線的空時編碼已被證明具有高效率之傳送分集技術。然而，在接收端對於這些技術之傳統的空時方塊解碼演算法(例如：最大比值合併(Maximum Ratio Combining, MRC)及最小均方誤差(Minimum Mean Square Error, MMSE)必須知道通道狀態資訊(可經由導引信號(pilot signals)估得)以執行空時解碼。近來，對於多載波－分碼多工接取(Multi-carrier Code Division Multiple Access, MC-CDMA)系統而言，基於盲蔽子空間(Subspace)之通道估測演算法(不需要事先傳送導引信號)也被提出，在接收端提供通道狀態資訊以執行空時解碼。本篇論文中，我們提出兩種在接收端不需要知道通道狀態資訊之盲蔽空時解碼(Blind Space-time Decoding, BSTD)演算法(演算法1及演算法2)，用於多根傳送天線及接收天線之同步空時編碼－多載波－分碼多工接取(Space-time Coded Multi-carrier Code Division Multiple Access, STC-MC-CDMA)系統。我們提出的演算法1(或演算法2)本身是疊代式演算法並具有與快速峰度最大化演算法(Fast Kurtosis Maximization Algorithm, FKMA)相同的超指數(super-exponential)收斂速率之優點。緊接著，我們藉由一些模擬結果來證實所提出的演算法之效能並於最後做一些結論。

Space-time coding schemes using multiple transmit antennas have proven efficient for transmit diversity in wireless communications. However, these schemes require channel state information (estimated through pilot signals) for the conventional space-time block decoding algorithms (such as maximum ratio combining (MRC) and minimum mean square error (MMSE)) at the receiver. Recently, blind subspace based channel estimation algorithms (without need of pilot signals) were also considered to provide the channel state information for space-time block decoding of a multicarrier CDMA (MC-CDMA) system at the receiver. In this thesis, two blind space-time de-coding (BSTD) algorithms (algorithm 1 and algorithm 2), which do not require
channel state information for space-time decoding at the receiver, are proposed for the synchronous MC-CDMA system with multiple transmit and receive antennas used. The proposed algorithm 1 (or algorithm 2) is an iterative algorithm using Chi and Chen computationally efficient fast kurtosis maximization algorithm with su-per-exponential convergence rate. Some simulation results are presented to support the efficacy of the proposed BSTD algorithms. Finally, some conclusions are drawn.

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