在本論文中，我們主要是研究在空間分集和時間分集的合作式通訊系統中效能比較之議題。藉由分集的技術，我們可以用來對抗通道的衰減和雜訊干擾，增加我們通訊的品質，提升傳送成功的機率。一般通訊系統常使用空間分集的策略來提升傳輸效能，利用中繼節點幫助來源點做訊號轉傳的功能，而其效能會依據中繼節點的佈放而有所差異。空間分集的策略為在一段時間間隔下來源點做兩次訊號的傳送，利用這樣的時間分集來提高傳輸的品質，而我們試圖使用時間分集來跟空間分集做比較，希望在空間分集較差的情況下能使用時間分集來取代空間分集，進而提升傳輸效能。此外，為了比較空間分集和時間分集的效能，我們引入中斷機率來做為兩種分集比較的基準，並計算出兩者的分集級數，藉此比較哪一個分集能提供較好的傳輸品質。在我們的研究中，我們計算出兩種分集的轉換分界點，根據這個分界點，我們可以改變我們時間分集中時間間隔的多寡來決定我們要使用哪一種分集。而我們也發現假如中繼節點放在離來源點及目的節點很近的位置，空間分集總是能夠獲得比時間分集較高的效能。最後，我們的數據模擬結果顯示出我們研究的可行性，且根據中繼節點佈放位置的不同，時間分集確實有可能獲得比空間分集較佳的傳送效能，但當佈置在近距離的情況下，空間分集總能提供較好的傳送品質。

In this thesis, we study the cooperative communication with spatial diversity and time diversity. Diversity techniques are attractive as they can be combined with other forms of diversity to against the fading or some interference in the wireless channel. We want to compare the spatial diversity and time diversity strategies by using the outage probability. Then we consider the diversity order of these two diversity strategies, and supply a method to decide which diversity strategy is better than the other. The numerical result will show the outage probability and count the diversity order of spatial diversity and time diversity strategies. We find a threshold which is a change point between these two strategies, and determine an area which spatial diversity is always better than time diversity.

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