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以令牌桶機制為基礎的IEEE 802.16允許控管以及上行封包排程江啟宏, Chiang,Chi-Hung Unknown Date (has links)
IEEE 802.16標準是針對無線城域網路(Wireless Metropolitan Area Network)而設計的,它支援服務品質(QoS),而且具有相當高的傳輸速率。每一種應用服務都有不同的型態,根據這些不同的型態,802.16 定義了四個不同的服務品質類別。然而,最關鍵的部份-封包排程卻沒有被定義在802.16標準裡面。在這篇論文中,我們提出了一套完整的允入控管(call admission control)和上行封包排程的架構。首先,我們先以令牌桶(token bucket)機制為基礎,設計了一套802.16專用的允入控管和上行封包排程的模組。接著我們介紹如何將令牌桶機制套用至一般的連線。我們找出了一個預測連線的延遲(delay)和漏失率(loss rate)的模型,接著可以利用這個模型,並透過簡單的搜尋演算法來找出適合的令牌速率和令牌桶的大小。模擬的結果表示,我們的允入控管和上行封包排程能夠確實對具有即時性質的連線的提供保證,且我們將令牌桶機制套用到一般連線的模組也能準確的運作。最後,我們也提出了一個簡單的整合實例並評估其效能。 / The IEEE 802.16 standard was designed for Wireless Metropolitan Area Network (WMAN). It supports QoS and has very high transmission rate. According to different application types, there are four QoS classes defined in the IEEE 802.16 standard. The key part of 802.16 for QoS– packet scheduling, was undefined. In this thesis, a complete call admission control (CAC) and uplink packet scheduling is presented. We first proposed a token-bucket based uplink packet scheduling combined with CAC. Then a model of characterizing traffic flows by token bucket parameters, namely token rate and bucket size, is presented. We proposed a queuing model to predict the delay and loss rate for a token bucket controlled traffic flow. In order to fulfill token bucket based CAC, we need to find appropriate token rate and bucket size for any flows. A simple search algorithm coupled with our queuing model can be used to achieve this. Multiplexing of two traffic flows is also introduced. The simulation results show that our CAC and uplink packet scheduling can promise the delay requirement of real-time flows and prevent each class from starvation. The precision of our token rate estimation model is also validated. Finally, a simple integration of our CAC, uplink scheduling, and multiplexing is evaluated.
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IEEE 802.16與802.11e整合環境的服務品質保證 / QoS Guarantee for IEEE 802.16 Integrating with 802.11e張志華, Chang, Chih-Hua Unknown Date (has links)
802.16與802.11e均有提供服務品質(QoS),但是其MAC並不相同,為了達到QoS的保證,我們使用馬可夫鍊(Markov Chain)模型分析在不同連線數量時802.11e EDCA的延遲時間(delay time)。然後,我們可以再利用允入控制(CAC)機制限制連線的數量以保證延遲時間的需求,並使用令牌桶(Token Bucket)機制,在滿足延遲及頻寬的需求下控制輸出流量,在我們的令牌桶機制中可以依照頻寬需求的變化自動調整令牌(Token)產生速率,最後使用封包丟棄機制提升吞吐量(throughput)。
在提出我們的方法後,我們使用Qualnet模擬器驗證延遲時間、封包丟棄率及吞吐量,結果表示我們所提出的方法在三方面都有明顯的改進。 / IEEE 802.16 and 802.11e both provide Quality of Service (QoS), but the MAC of betweens is different. Ensuring the QoS guarantee, we use a Markov Chain model to analyze the 802.11e EDCA delay time under variance number of connections. Therefore, we can employ a CAC mechanism constraining the number of connections to guarantee the delay requirement. Further, considering the delay requirement and the bandwidth, we use a Token Bucket mechanism to throttle the traffic output that ensures the delay and bandwidth to be satisfied. And our Token Bucket mechanism can tune the token rate automatically by bandwidth requirement. Finally, we use the Packet Drop mechanism to improve throughput.
After my methodology, we validate the delay, packet drop rate and throughput by simulator Qualnet. We have significant improvement in delay, drop rate, and throughput.
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