本論文裡，主要討論在一個無線網路的環境裡，利用快速下載的方法下載廣播資訊。而網路廣播站則是使用群播的方式播放MP3音樂到網路裡，而使用者可以在無線網路上收聽MP3音樂同時也可以把廣播音樂複製到檔案裡。 當移動者離開無線網路服務區時，因訊號強度不夠而無法正常地連接到網際網路。所以當使用者在跨越不同服務區時，會遺漏在換台(handoff)期間播出的MP3音樂訊息。所以在離開服務區前使用快速下載的方法，把尚未收聽的MP3音樂的部份，平行地快速複製到儲存區資源，讓使用者在換台時可以順暢地繼續收聽完整的MP3音樂。 本文除了提出快速下載的構想，亦討論不同快速下載的演算法。經過比較，選出一個較適合網路廣播站、實作較容易、也適用於即將離開服務區使用者的快速下載演算法，做為本系統實作時的依據。而快速下載的方法則是利用檔案切割的原理。把一首MP3音樂檔切割為N等份，同時把已經切割的檔案由不同的頻道同時播放出來。所以當使用者正要換台時，可以從不同的頻道上把廣播資訊快速地下載回來。當下載回來後，用檔案合併的方式合併成一首完整的MP3音樂。 In the thesis, We discuss the fast downloading of the multicast multimedia information on wireless environment. The multimedia information is playing the MP3 music on the network using method of multicasting. When users receive MP3 music on the network, they can copy multimedia information to the files at the same time. On wireless environment, when mobile users leave the service range of base station, they will not to be connecting to the Internet at some moment. The mobile users may receive only some middle part of full song music in connection time. It has problems when user are mobile to leave the current service range. We conquer this problems by using the method of the fast downloading, before we leave the service range. We discuss many different algorithms of fast downloading, and the method of regular broadcasting with fast downloading on leaving is suitable for multicasting multimedia information, easy to implementation . The principle of the fast downloading is dividing MP3 music stream into N parts and playing the divided MP3 music on the different channel. Before mobile users leaving the service range, they can concurrently download the multicasting multimedia information on the different channel. After fast downloading, using method of the file merging combines the received dump.mp3 files into pre-stored song of MP3 music completely.
