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博碩士論文 etd-0707103-142707 詳細資訊
Title page for etd-0707103-142707
論文名稱
Title
在無線網路中以錯誤發生率為參考來動態調整加權公平排程法之研究
Error Rate Based – Dynamic Weighted Fair Queuing In Wireless Network
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
47
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2003-06-18
繳交日期
Date of Submission
2003-07-07
關鍵字
Keywords
佇列、公平性、排程、無線網路
Wireless Networks, Queuing, Scheduling, Fairness
統計
Statistics
本論文已被瀏覽 5659 次,被下載 1994
The thesis/dissertation has been browsed 5659 times, has been downloaded 1994 times.
中文摘要
在有線網路中,排程演算法已經有相當多的研究及方法,因此在有線的領域中,排程演算法的研究已經是相當的成熟,但對於無線網路來說,排程演算法的研究卻不如有線網路來的成熟。這是因為無線網路相對於有線網路有著以下的特性,使得有線網路的排程演算法無法直接應用到無線網路上,而必須重新研究一些改良的方法:
1.無線網路的頻寬較少
2.無線網路會有Location Dependent Errors
3.無線網路有較高的Bursty channel error rates
因此在研究無線網路的排程演算法時,公平性的問題、QOS、整體的Throughput是否提高及channel是否有效利用是評定此無線網路排程演算法是否適當的重點因素。

在這篇論文中,首先介紹有線排程演算法及其它無線排程演算法,分析這些演算法的優點及缺點後,我們提出一個以WFQ (Weighted Fair Queuing) 為參考基礎,根據每個channel所受到的error rates來動態調整其weights的排程演算法,在這個方法之下,BS (Base Station)會根據mobile hosts的weight及error rate相對於整體的比值來動態分配頻寬,在此原則之下,error rates較高的user不會因為佔用著太多頻寬而形成浪費,使得整體的throughput下降,而error rate較低的user也可以因為藉由動態調整weight來增加頻寬使用權,使得整體的throughput獲得改善。至於調整後的weight是否會造成user間的不公平,我們也會進一步的討論。
Abstract
In wired network, there are many researches about scheduling algorithm. As for wireless network, the scheduling algorithm is not maturer than wired network. And there are some following characteristics of wireless network that we can not make use of wired scheduling algorithm directly:(1)Less bandwidth in wireless network;(2)Location dependent errors;(3)Higher error rate and bursty error. So when we design the wireless scheduling algorithm, there are some important issues we should take into account:
(1)Fairness ;
(2)QOS ;
(3)Whether the overall throughput rises or not;
(4)Whether the bandwidth is best utilized or not

In this paper, we introduce the wired and wireless scheduling algorithm separately and discuss the advantage and disadvantage of these methods first. And we propose a scheduling algorithm which is based on WFQ [1] and dynamically adjusts weights according to the error rate of each flow. In this method, the base station will allocate the bandwidth by calculating the weight of mobile hosts and the proportion of error rates to the whole body. And during the process of adjusting, we will prevent the weight of a certain channel from increasing or decreasing excessively which might lead to unfair phenomenon. Under this adjustment, we will raise the whole throughput and maintain the fairness of all users.
目次 Table of Contents
中文摘要……………………………………………………………………………i
Abstract……………………………………………………………………………ii
Chapter 1 : Introduction ……………………………………………………1
Chapter 2 : Related Work ……………………………………………………4
2-1 Scheduling Methods In Wired Network……………………………4
2-1-1 Network Model……………………………………………………4
2-1-2 Wired Scheduling Algorithms…………………………………5
2-1-2A Round Robin Scheduler……………………………………5
2-1-2B WRR-Weighted Round Robin Scheduler……………………7
2-1-2C FFQ-Fluid Fair Queuing……………………………………8
2-1-2D WFQ-Weighted Fair Queuing………………………………9
2-1-2E WF2Q-Worst Case Fair Weighted Fair Queuing…………9
2-1-2F WFQ and WF2Q Example………………………………………10
2-2 Scheduling Methods In Wireless Work……………………………12
2-2-1 Network Model……………………………………………………12
2-2-2 Wireless Scheduling Algorithms………………………………13
2-2-2A CSDPS-Channel State Dependent Packet Scheduling..13
2-2-2B CSDPS+CBQ-CSDPS +Class Based Queuing…………………15
2-2-2C SBFA-Server Based Fair Approach………………………16
2-2-2D ICSDPS-Improved CSDPS……………………………………19
2-2-2E ELF-Effort Limited Fair Queuing………………………23



Chapter 3 : Proposed Method-Error Rate Based Dynamic WFQ…………26
3-1 Design Issue…………………………………………………………26
3-2 System Model…………………………………………………………27
3-3 Error Rate Based Dynamic WFQ……………………………………28
3-3-1 Introduction……………………………………………………28
3-3-2 Adjusting Algorithm……………………………………………30
3-3-3 Adjusting Formula………………………………………………32
3-3-4 Fairness…………………………………………………………35
Chapter 4 : Error Rate Based Dynamic WFQ Simulation…………………38
4-1 Simulation Environment………………………………………… 38
4-2 Simulation Models………………………………………………. 38
4-2-1 Different β with the same α………………………………………………………39
4-2-2α= 0.1 β= 0.5……………………………………………………41
4-2-3α= 0.5 β= 0.5……………………………………………………42
4-2-4α= 0.9 β= 0.5……………………………………………………43
4-3 Discussion and Analysis……………………………………………44
Chapter 5 : Conclusion and Future Work…………………………………45
Reference…………………………………………………………………………46
參考文獻 References
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