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    Title: 具服務品質機制IEEE 802.16 無線都會型網路頻寬允入控制之研究
    Other Titles: Admission control for quality of service in IEEE 802.16 wireless metropolitan area network
    Authors: 謝其均;Hsieh, Chi-chun
    Contributors: 淡江大學電機工程學系碩士班
    李維聰;Lee, Wei-tsong
    Keywords: 允入控制;服務品質;無線都會型網路;Admission Control;Quality of Service;IEEE 802.16
    Date: 2007
    Issue Date: 2010-01-11 07:06:58 (UTC+8)
    Abstract: IEEE 802.16是針對支援都會型無線網路以及微波頻帶提出的一種新的通訊標準,並且以無線的方式取代最後一哩的寬頻網路接取。因為使用了高效率的無線訊號傳輸,所以傳輸距離最遠到達48km,末端的頻寬有300Kbps~2Mbps,與傳統的有線網路做比較,其硬體鋪設較為快速,且不受地形的影響以及低成本的特性,其主要是應用在單點對多點間的無線寬頻傳輸,並設定在無障礙空間範疇內傳輸。
    由於802.16系統支援各種不同的傳輸服務,服務品質要求各不相同,為求系統資源的最有效利用提供最佳服務品質,因此針對IEEE802.16提出頻寬分配及資源管理(Quality of Service)是非常重要的研究方向,而在IEEE 802.16中依據服務特性的不同,提供了五種形式的傳輸品質,包含了非請求的頻寬分配服務(UGS)、延伸即時可變速率服務(ERT-VR)、即時可變速率服務(RT-VR)、非即時可變速率服務(NRT-VR)、盡力傳送服務(BE)。
    在常見的相關論文中針對IEEE 802.16的頻寬分配及資源管理提出相關的方法,在BS(Base Station)端必須針對SS端(Subscriber Station)所提出的不同服務需求,先執行允入控制的判斷,此步驟依照頻寬的分配,決定是否接受或拒絕SS端所提出的需求,之後再根據所提出服務需求的等級不同,來決定其優先權等級,最後在依據其優先權等級及所提出的頻寬需求分配其所需要的頻寬。其中大多是針對延遲及頻寬分配之問題做詳細的探討,但是並未針對訊務的傳輸時間作探討。
    因此本篇論文提出一個不同的允入控制法則來有效的進行頻寬需求的判斷,其方法是針對QoS中的非請求的頻寬分配服務部份提出改善,並將重新依據非請求的頻寬分配服務參數及傳輸間隔的大小來效率地分配頻寬。當發生衝突的情況時,將會依照非請求的頻寬分配服務的延遲時間參數來解決這個問題,有較大的可容許時間參數當發生碰撞時其頻寬就可以分配在較晚的時間,而較小的可容許時間參數就必須在較早的時間被分配。最後,我們的實驗將會使用IEEE 802.16的模組在NS2軟體平台上進行模擬,並定義相關的QoS參數,依照上述的方法其結果網路傳輸可以接受更多的服務需求,且對於網路的流量(throughput)有較好的改進。
    IEEE 802.16 is a new communication standard for supporting the Wireless Metropolitan Area Network and the microwave and the milliwave frequency band. IEEE 802.16 replaces the last one mile by the way of wireless connects and fetches. Because it used high-efficiency wireless signal transmitting and treatment technology, it is farthest to 48km to transmit the distance, wide 300Kbps- 2Mbps frequently of end. Compared with the tradition wired network, IEEE 802.16 possesses the characteristics of the fast laying of hardware, being free from the effect of topography, and low cost. The orientation of its application is mainly on wireless broadband transmissions of Point-to-Multipoint, and transmissions of Line Of Sight.
    In common relative papers, they proposed the related method to be aimed at bandwidth allocated in IEEE802.16 and Quality of service. In Base Station(BS) part, BS must perform the decision of admission control according to the different service requests from SS. This step is determining whether BS accepts or rejects the requests from SS. Then based on the different classes of asked service requests, BS determines the priority class. Finally, BS allots the bandwidth by the priority class of the requests.
    In this paper, we proposed a different admission control method for improving the UGS part of QoS. This method is improving the part of UGS in QoS and effectively allotting bandwidth according to the parameter of UGS and the size of transmission interval. When the situation of conflict is happened, we will solve the problem by the delay time parameter of UGS. Finally, we will simulate our experiment by using the IEEE 802.16 model on NS2 software platform, and will define related parameter. We can accept and tolerate the requests having longer delay time, and make admission control to accept more service requests.
    Appears in Collections:[電機工程學系暨研究所] 學位論文

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