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標題: | 在802.11和802.16交互網路環境下保證服務品質的動態需求預測與資源保留機制 Demand Prediction and Resource Reservation for QoS Internetworking of 802.11 and 802.16 Networks |
作者: | Ya-Hua Lin 林雅華 |
指導教授: | 孫雅麗(Yea-Li Sun) |
關鍵字: | 802.16,資源管理,資源保留,週期,收入,成本,流量預測, 802.16,resource management,resource reservation,period,incom,cost,traffic prediction, |
出版年 : | 2007 |
學位: | 碩士 |
摘要: | 以802.16網路作為802.11網路後置網路(backhaul network)的交互網路裡,SS扮演著連接兩個異質網路的角色,為了減少SS和BS之間的訊息交換並有效地使用資源滿足802.11網路的傳輸需求,我們提出一套SS端的動態資源管理機制。利用Decision Period(DP)的概念令SS以多個frame為單位向BS提出頻寬需求,減少SS和BS之間的溝通頻率;並導入收入-成本模型,以收入和成本的觀念來牽制SS對資源的使用,一方面保留資源用以傳輸封包來獲取服務收入,一方面利用保留成本避免SS為增加收入而無限制地保留資源,利用延遲服務成本避免SS為減少保留成本而累積封包不傳輸的行為。由於SS是以DP為單位作決策,我們提出三種預測方法來預測未來一個DP每個frame之封包新進量,作為資源保留決策的參考。由於每次保留決策影響所及的範圍是一個DP,考慮到一個DP裡時間資源的不可儲存性和封包可無限往後累積的特性,我們的保留決策是基於三點來作考量-(1)減少服務被延遲的可能性;(2)增加已保留資源的使用率;(3)減少服務成本。
實驗結果顯示,無論來源端的類型為何,根據三種方法作預測所得的淨收入與已知實際封包新進量的最佳決策結果之淨收入都相去不遠,而且以DP為單位作決策的結果之平均淨收入幾乎總是比frame-by-frame作決策的結果還高。 In the internetworking of 802.16 and 802.11 networks, the 802.16 SS plays the role connecting these two heterogeneous networks. To reduce the amount of messages exchanged between SS and BS and effectively use the resource to satisfy the requirement of packet transmission in 802.11 networks, we propose a dynamic resource management mechanism on SS. To reduce the communication frequency and message amount between SS and BS, instead of requesting resource frame by frame, we introduce the concept of Decision Period (DP)which consists multiple frames (e.g., a DP contains m concecutive frames) and SS requests resource from BS every m frames. We introduce the Income-Cost Model which uses the idea of service fee and reservation/block-off cost to evaluate the performance. In this model, the SS uses the reserved resource to serve packets in order to take in income. It will be charged with the block-off cost for each packet it fails to serve. Because the SS can not know the future arrival traffic in advance, it may conservatively reserve more resources than backlogged requirement, to the extreme, it may reserve the maximal allowable resources at each DP. However, it can not arbitrarily reserve all the resources because they are per unit charged with the reservation cost. We have to predict the new-arrival traffic of multiple frames in next DP and make reservation decision based on these predictions. Because a single reservation decision applies to multiple frames (i.e., a DP), the difficulty of our problem is that: the reserved time resource is unstorable (it will be wasted if reserved and not used) but the unserved packets will be accumulated infinitely. We propose three approaches to predict the amount of new-arrival traffic of each frame in next DP. Our reservation decision is based on three objectives-(1)minimize request blocking probability;(2)maximize resource utilization;(3)minimize cost。 According to experimental results, for all kinds of source traffic considered, the net profit from reservation decision based on the prediction of three approaches all close to that from optimal reservation decision based actual arrival. Also, in most cases, our mechanisms achieve higher average net profit per frame with decision on the basis of DP than that with frame-by-frame decision. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/29082 |
全文授權: | 有償授權 |
顯示於系所單位: | 資訊管理學系 |
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