[[alternative]]A Dynamically Schedule Algorithm for Wireless Broadcast

[[abstract]] 在無線網路的拉式架構之下，客戶端向伺服器端請求播送資料，為了解決冷、熱門資料不同點播率及客戶端請求之後等待時間過久的問題，伺服器端同時考慮資料項的被點播率與客戶端請求資料的等待時間之後，再決定播送的資料項。在真實的環境之下，資料項的被點播率與客戶端請求的等待時間會隨著時間而不斷改變。若同時考慮上述兩個因素，伺服器端在每次廣播前必需重算全部資料項的權重值，再決定廣播的資料項，這是非常耗資源且低效率的方法。為了解決這樣的問題，我們提出動態排程演算法(DYSA)來解決上述的問題。DYSA使用資料項的權重值來維護最大堆積樹，以供快速廣播資料項。此外，我們利用索引的技巧來加速堆積樹裡資料項的存取。在最後的模擬實驗結果顯示，在動態環境的要求下，DYSA比一般演算法有更好的執行效能。[[abstract]] In the pull-based wireless network, clients request data items from a server. In order to solve cold and hot data, and reduce clients' waiting timer, server considers hit rate of data items and waiting time of requests for broadcasting. The hit rate of data items and the waiting time of requests always changed along with time elapsed. Therefore, server has to calculate overall weight value of data items and decides maximum weight value of data items before broadcasting. In order to increase performance of server, we propose a dynamically schedule algorithm (DYSA) for wireless broadcast. The DYSA uses weight value of data items and maintains them in a maximum heap tree for quickly broadcasting. Furthermore, we present a indexing for accessing a data item's information faster. The experiment results show that our method has more effectively than a common algorithm in the dynamic wireless environment