此篇論文主要是探討在有一個擁有頻道使用權利的多天線使用者 (primary user, PU) 的環境下，設計一個多重輸入/輸出 (multi-input, multi-output, MIMO) 的感知通訊 (cognitive radio, CR) 中的次要使用者 (secondary user, SU) 系統。設計這個系統兩個主要部份：1. 在機率條件下針對通道的不確定性上對主要使用者造成的干擾的分析 以及 2. 在次要使用者的接收端針對通道不確定性的設計。次要使用者在傳輸的時候必需針對主要使用者和次要使用者之間的通道不確定性來限制對於主要使用者機率上的干擾。為了設計一個在機率上干擾條件下僅在接收端有通道資訊(channel state information)的系統，次要使用者採用正交時空區塊碼 (orthogonal space time block code, OSTBC) 作為編碼。另一方面，在次要使用者的接收端也需要針對次要使用都的傳送端與接收端間的通道不確定性做設計。本篇論文在給定的機率干擾絛件下，將觀察時間最小化使得頻帶使用效率可以最大化。接著，我們分析對於感知使用者傳送端與接收端因為通道訊息估計所□生的通道不確定性並且分析其與接收端設計的關係。最後，我們會摸擬並且分析對於干擾主要使用者的機率以及次要使用者間的誤碼率 (bit error rate) 的結果。對於模擬的結果，我們可以得知此篇論文的架構是可行的。

This thesis consider a multi-input-multi-output (MIMO)
cognitive environment with a multi-antenna primary user (PU) who has the spectrum license and does not cooperate with the cognitive user (CU). This thesis addresses two problems: 1. the robust cognitive transmission subject to the probabilistic interference constraints to the PU, and 2. the robust cognitive receive beamforming subject to the channel uncertainties. The CU transmits the signal opportunistically with constrained interference to the PU on the influence caused by the channel estimation errors at the cognitive system. The probability of the interference from CU to
PU exceeding the tolerant threshold is constrained and trades off with spectrum utilization efficiency. With constrained interference to PU, the CU encodes signals on the orthogonal space time block code (OSTBC) s.t. the cognitive system is channel state information only at the receiver (CSIR). On the other hand, the robust receiver is directed against the channel uncertainties between transmitter and receiver caused by training estimation
error. In this thesis, we keep the interference from CU to PU under a probabilistic threshold and maximize the spectrum
efficiency by minimize the observation duration. Therefore, we analyze the channel uncertainties between CU's transmitter and receiver caused by training error and find the robustness corresponding to the estimation errors. Finally, we simulate the probability of the interference exceeding tolerant threshold at the PU and the BER performance of the CU. From the simulation results, we make sure that the analysis of cognitive scheme is workable.

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