軟體定義行動網路交遞延遲分析: 網路微積分方法之探討

Abstract

軟體定義網路(Software Defined Network, SDN)在次世代行動網路中扮演一個非常重要的角色，它擁有可擴展和客製化的特性，這是現今網路所缺乏的。隨著軟體定義網路和行動網路結合，控制器必須要處理因使用者不斷交遞而造成的繞送延遲問題。為了減少交遞延遲，數種預設路徑演算法分別在文獻中被提出，雖然這些方法能夠降低使用者交遞延遲，但演算法的效能分析模型仍然是一個開放性的議題。我們建立使用者交遞延遲分析模型，在未來的行動網路中，針對不同延遲需求的服務提供交遞延遲預測，並根據預測結果和使用者需求建立繞送路徑。在我們研究中，我們使用網路微積分來分析交遞延遲的上界值，為了計算從閘道器傳輸封包到基地台的串聯系統延遲，我們延伸了現有的多工只付一次演算法(Pay Mul-tiplexing Only Once,PMOO)，針對先進先出多優先序系統進行分析，為不同優先順序的使用者分別提供交遞延遲上限。最後則透過模擬來驗證我們提出的數學模型是可靠的，我們的研究顯示出網路微積分的延遲分析在次世代行動網路中將是非常具有影響力的。

With the great potential in flexible network provisioning, software-defined network (SDN) has been considered as one of the most promising network architectures in the next generation mobile networks. However, the rule management in SDN-enabled mobile networks becomes a challenging task due to rapid topology changes caused by user mobility. In order to reduce handoff delay, different prefetching approaches have been proposed. Even though these prefetching approaches are efficient, measuring handoff delay performance of these methods is an important open issue. Hence we aim to develop an analytical model to predict handoff delay and set up the routing path based on the predicted result and user requirement. For SDN-enabled mobile networks, we develop an analytical handoff delay performance model based on network calculus theory. In order to analyze the delay bound of the concatenation system from gateway to base stations, we adopt pay multiplexing only once method (PMOO) into first-in-first-out (FIFO) multi-priority system. Also, we derive the delay bound for each priority flow. The derived delay bounds in different network environments are validated by simulations. We show that the presented network-calculus-based delay analysis methodology can be effective in evaluating delay performance of communications systems.