無線網路頻道環境之自我時間控制封包排程機制; Channel Condition aware Self-Clocked Packet Scheduling for Wireless Networks

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/9366

Title:	無線網路頻道環境之自我時間控制封包排程機制;Channel Condition aware Self-Clocked Packet Scheduling for Wireless Networks
Authors:	盧翔煒;Hsiang-Wei Lu
Contributors:	資訊工程研究所
Keywords:	無線網路公平演算法;wireless scheduler;wireless fair queueing
Date:	2007-06-20
Issue Date:	2009-09-22 11:46:16 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	在無線網路下，移動式主機會因為所在的位置而遭受不同的頻道錯誤，而無法有效地傳送與接受封包，因此，對於有線網路上的封包公平佇列演算法並不能直接應用到無線網路。一般而言，在無線網路上，當移動式主機遭受頻道錯誤時，封包公平佇列演算法會保留資料流的虛擬時間。這能使得移動式主機在能傳送資料時，能擁有較高的優先權。同時，系統會開始對移動式主機補償他所失去的服務。這也許會使得長期處於無法傳送資料的移動式主機佔據整個共享頻道及影響其它移動式主機的資料傳送。在此，我們提出了頻道條件自我時間控制封包演算法。這演算法除了能克服上述問題同時能達成以下目標（１）在訊號無錯誤的系統中，提供延遲與吞吐量的保證（２）對於無訊號錯誤的移動式主機，提供瞬時的公平性（３）在可能發生頻道錯誤的系統下，保持傳輸公平性（４）對無頻道錯誤的移動式主機，提供延遲穩定的服務品質。我們的排程演算法是建立在SFQ資源調度演算法上，當移動式主機預測到下次傳送封包時會發生頻道錯誤而無法正常的接收資料，移動式主機的資料流會重設它的虛擬時間，以爭取下次傳送資料的機會。 Since mobile hosts suffer from bursty and location-dependent channel errors in wireless networks, Packet Fair Queueing algorithm in wireline networks cannot be applied directly to wireless network. Generally, fair scheduler in wireless network retains virtual time of flow when the flow encounters channel errors. This results that the flow has higher priority when it exits from errors. And the system can compensate the lost service for the flow. This causes that the lagging flows capture the share channel and effect queue delay of flows perceiving clean channel. In this paper, we present Channel-condition Self-Clocked Packet Scheduling. This algorithm can address the problem and achieve these goals (1) delay and throughput guarantees in error-free environment (2) short-term fairness among flows perceiving error-free (3) long-term fairness for error system (4) steady jitter for flows perceiving error-free. Our algorithm is based on Start-time Fair Queueing and the virtual time of flows is reset to contend for forwarding its packet at next time when errors happen for the flow.
Appears in Collections:	[Graduate Institute of Computer Science and Information Engineering] Electronic Thesis & Dissertation

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