非同步傳輸模式網路中以輸入訊務功率頻譜為基礎的允諾控制策略

Abstract

非同步傳輸模式 (ATM) ， 因為具有彈性並且可以很有效率地收容各種不 同型態的服務，已被視為是最適合於寬頻整合服務數位網路之傳輸模式 。 然而在非同步傳輸模式網路中為確保服務品質 (QOS) ，允諾控制是一 項重要的課題。在此篇論文中，我們提出一個以輸入訊務功率頻譜為基礎 的允諾控制策略。首先，我們探討輸入訊務功率頻譜對一個非同步傳輸模 式網路節點佇列行為的影響，討論不同輸入訊務功率頻譜對於系統效能的 關係。結果顯示功率頻譜中的直流成份、平均功率及半功率頻寬是影響系 統效能的重要因素。我們也提出了一個依據等效平均功率來估算服務品質 的方法。然後根據服務品質的要求，我們找出不同負載量所能容忍的最大 等效平均功率，建立一個允諾控制表。根據此表決定是否接受一個新的連 線要求。模擬結果顯示這是一個對非同步傳輸模式網路很有效率的允諾控 制策略。 Owing to the ability to flexibly accommodate verstile services, ATM (Anynchronous Transfer Mode) is considered to be the most suitable transfer mode for B-ISDN (Boardband Integrated Service Digital Network). However, in order to ensure the quality of service (QOS) for each service, connection admission control is an important issue for ATM networks. In this thesis, we propose a power-spectrum based connection admission control strategy for ATM networks. At first, we study the impact of input rate power pectrum on the queueing behavior of an ATM network and we discuss the relationship between the input rate power spectrum and the system performance. The results show that the DC component, the average power and the half-power bandwidth of the input power spectrum are important factors to the system performance. Also, we propose a method to approximate the QOS by the equivalent average power. Finally, we construct an admission control table which contains the maximum acceptable equivalent average power for different traffic load with respect to the required QOS. Whether a new call should be accepted or not is determined by table lookup. Simulation results show that this is an efficient connection admission control strategy for ATM networks.