個人通訊服務資料庫系統中即時排程策略之效益評估

Abstract

在個人通訊服務系統中，網路管理者必須追蹤手機的位置，使得任何呼叫 都可被傳送到目的手機上。目前，被廣泛使用來儲存手機位置的為一兩階 層式的資料庫系統。本論文之主旨即在研究如何讓此資料庫系統符合即時 的需求。在一些假設下，我們設計了此個人通訊服務資料庫系統的模擬環 境，並在這個模擬環境下，做了一系列的實驗去評估各種即時排程策略的 效能。經由實驗結果分析，我們提出了以下幾點建議給服務供應者，用以 發展高效能的通訊服務資料庫系統。第一點，即時排程策略對改進系統的 效能幫助很大；第二點，增加HLR的硬體資源可以明顯的增進效能；第三 點，讓遠端存取有較高的優先權，可避免瓶頸資料庫影響其它資料庫的效 能；第四點，主記憶體資料庫對增進系統的效能貢獻有限；第五點，手機 的移動速率會嚴重影響系統效能。因此在設計排程策略時應考慮這些因素 。 In Personal Communication Services (PCS), the network tracks the locations of the mobile stations so that incoming calls can be delivered to the target mobile stations. At present, a two-level mobility database system is extensively used to store location information of the mobile stations. In this paper, we aim to investigate how to meet real-time requirements for the mobility database system. Under some assumptions, a set of experiments have been conducted to evaluate the performance of various real- time scheduling policies. Based on the experimental results, the following suggestions are given for PCS provider to design a high-performance mobility database system. 1) The evaluated real-time scheduling policies have significant impact on improving the performance. 2) Increasing power of HLR can obviously improve the performance. 3) Giving remote accesses higher priority to enter the system can decrease the effect of overload spreading by the bottleneck site. 4) Memory resident databases make little contribution to improving the performance. 5.) Mobility rate of mobile stations seriously affects the performance.