在無線廣播環境下，手攜式行動裝置可以在任意的地點向遠端的伺服器發出所需資料請求，但基於無線網路頻寬為有限且非對稱式情況下，下載頻道大於上傳頻道頻寬而言，遠端伺服器必須要有效率且週期性的廣播查詢請求至行動裝置客戶端的手上。 在無線環境中，伺服器接收到來自不同客戶端的資料請求，並根據查詢請求來決定資料的廣播頻率以降低客戶端查詢請求的平均等待時間。 在現實環境中，客戶端的查詢請求中常具有重複的資料項，伺服器若能考量不同查詢請求彼此的關聯性並應用於廣播排程中將可進一步降低客戶端查詢的平均等待時間。 本篇論文針對無線廣播環境下，不同客戶端的查詢請求彼此間關聯性提出一個及時的廣播排程修正方法，能夠根據不同客戶端的請求頻率決定資料的排程配置進而有效地降低整體客戶端的平均等待時間。最後由實驗結果可以證實本文提出的方法可以較有效率的降低客戶端的平均等待時間。 Under wireless broadcast environment, portable device can send query requests for data of need to the remote server from everywhere. Considering the limited bandwidth and asymmetry of data transmission rate from that downstream transmission capacity is far larger than upstream transmission capacity, the remote server have to broadcast requested queries to a large number of clients efficiently and periodically. The remote server constantly receives the data request from different clients. Among them hot data were broadcasted periodically in broadcast channel in order to reduce the reply rate in each individual channels. However, broadcast the different requested data with different broadcast rate can lower the average waiting time of clients’ request. Since some hot data items can be part of different requested data from different clients accessing the same wireless database. If the correlation between each query were used in wireless broadcast schedule, the average waiting time for clients’ queries can be further reduced. This thesis aims at the wireless broadcast environment; it provide an improved algorithm for real time data broadcast schedule to reduce the average data waiting time at client according to the different queries request rate. Via the result of simulation experiments, using the proposed algorithm of this thesis, the average waiting time for clients’ queries can be efficient reduced.
