為了減少從網路下載檔案的等待時間，許許多多的檔案被置放於映射站台，讓使用者自由選擇站台來進行瀏覽、下載，不但節省下載時間，也分散伺服器的負載。不過，選擇傳輸速度最佳的站台並不是件簡單的事，若選擇錯誤，很可能得到的極低的傳輸效率。平行存取技術由此而生：同時與多個映射站台連線，分別從各站台下載檔案的不同部分，再組合為原來的檔案，不但可大幅加快下載速度，還可分散網路及伺服器的負載，以及避免困難的站台選擇工作。
平行存取技術的關鍵為，將檔案切分為許多區塊，分別從不同站台下載各個區塊的資料。不同的區塊尺寸可決定整體的下載效率，大致來說，區塊尺寸越大，下載效能越高。不過當區塊尺寸過大，由於各站台區塊傳輸結束時間的不一致，反而可能使下載時間增長。區塊尺寸過小或過大都可能降低效能，要如何選擇最佳的區塊尺寸是使平行存取技術達到高效能的重要研究。

在本篇論文中，我們研究檔案大小、區塊尺寸對於平行存取技術傳輸效能的影響，並建立區塊尺寸－下載時間模型，找出計算最佳的區塊尺寸的方法，並藉此發展出動態平行存取技術。

動態平行存取技術可動態地根據根據各站台的連線及下載情形以時間預估演算法來計算最佳的區塊尺寸，企圖在各種情況下皆能得到合理的下載效率。根據我們的評估，動態平行存取技術的表現雖然不若直接指定最佳區塊尺寸的平行存取技術，不過在各種情況下能夠獲得較穩定的表現。在我們的實驗中，動態平行存取技術通常能獲得理想下載速率 85% 以上的傳輸效能。

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