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題名 IEEE 802.16網狀網路環境中降低媒體存取延遲研究
Delay Reduction of Media Access for IEEE 802.16 Mesh Network
作者 林暐清
Lin, Wei Ching
貢獻者 張宏慶
Jang, Hung Chin
林暐清
Lin, Wei Ching
關鍵詞 網狀網路
降低延遲
媒體允入
WiMAX
mesh network
holdoff
delay reduction
media access
IEEE 802.16
日期 2007
上傳時間 8-Dec-2010 11:59:16 (UTC+8)
摘要 本研究在減低Wimax mesh mode環境中media access階段會造成的delay現象。我們發現當subscriber station (SS)訊務繁忙時，競爭transmission opportunity (TO)以及3-way handshake的過程容易失敗，造成傳輸效率降低，封包的delay也會增加。同時我們也發現封包的延遲還來自minislot的不良配置。因為原始的Wimax mesh mode對於minislot的配置會造成預約過晚的問題，當預約時間被延長，資料就必須無條件的增加等待時間，因此我們將針對這些問題進行改善，降低在訊務繁忙的狀況下，傳輸效率低落的問題。

我們使用兩種方式來改善上述的問題，其一是由Bayer [4]所提出的動態調整holdoff指數(dynamic holdoff exponent)的方式，藉由調整holdoff指數的大小來縮短holdoff時間，以縮短傳輸延遲；另外，我們也提出一個以節點的臨接區域為配置基準(Neighborhood-Based Minislot Allocation, NBMA) 的方法，透過與其相鄰的節點交換訊息，優化minislot的配置。我們用這兩種方式減少IEEE 802.16中媒體存取階段所造成的傳輸延遲。

實驗結果顯示，在網路負載較輕的情況下，NBMA可以有效的將delay降低為原來的七分之一，改善幅度將近85%，抖動率(jitter)的部分亦有20%的改善，並略為提高傳輸效能8%左右；而當網路負載較重時，delay的改善程度仍有40%左右，jitter部分改善了12%，傳輸效能亦有6%的改善。證明了我們的方法確實可行，並且在改善delay方面有顯著的效果。
IEEE 802.16 mesh network is a new environment of wireless network. It was designed as a self-organized, distributed scheduling, and multi-hop network. However, it is not robust enough to handle a heavy loading environment for lacking of QoS support. Our research is trying to reduce its media access delay, which comes from both TO (transmission opportunity) competition and improper minislot allocation. TO competition will extend the MSH-DSCH (mesh distributed scheduling) interval and slow down the exchanging speed of control message. Improper minislot allocation comes from the distributed scheduling of minislot. When a subscriber station (SS) allocates too much minislot for low-level traffic, it will defer the allocation of other neighbors’ high-level traffic.

We use Bayer’s [4] dynamic exponent to reduce holdoff time of SS, and speed up the exchange of control message. On the other hand, we design an “importance factor” (IM-factor) to score the importance of request. Through the exchange of IM-factor, SS and its neighbors will produce a threshold of IM-factor to filter the unimportant requests, and prevent minislot from being assigned too late.

In our experiments, the proposed methods can reduce 85% delay and 20% jitter, and increase bandwidth utility by 7%. It shows that our method in reducing transmission delay is pratical and effective.
參考文獻 [1] IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems, IEEE Std 802.16-2004. IEEE, 2004.
[2] M. Cao, W. Ma, Q. Zhang, and X. Wang, “Analysis of IEEE 802.16 Mesh Mode Scheduler Performance” IEEE Transaction on Wireless Communication, Vol. 6, NO. 4, April 2007.
[3] M. Cao, W. Ma, Q. Zhang, and X. Wang, “Modeling and Performance Analysis of the Distributed Scheduler in IEEE 802.16 Mesh Mode” Proc. ACM MobiHoc ’05, May 2005, pp.78-89.
[4] N. Bayer, B. Xu, V. Rakocevic, and J. Habermann, “Improving the Performance of the distributed Scheduler in IEEE 802.16 Mesh Networks”, Proceedings of Vehicular Technology Conference (IEEE VTC), Dublin, Ireland, April 2007.
[5] N. Bayer, B. Xu, V. Rakocevic, and J. Habermann, “Transmission Timing of Messages in IEEE 802.16 based Mesh Networks”, Proceedings of IEEE/VDE European Wireless, Athens, Greece, April, 2006.
[6] M.S. Kuran, B. Yilmaz, F. Alagoz, and T. Tugcu, “Quality of service in mesh mode IEEE 802.16 networks”, 14th International Conference on Software, Telecommunications and Computer Networks 2006, (SoftCOM `06), Split-Dubrovnik, Croatia, 2006, pp. 107-111.
[7] K. Wongthavarawat, and A. Ganz, “Packet Scheduling for QoS support in IEEE 802.16 broadband wireless access systems”, Int. J. Commun. Syst. Vol. 16, Issue 1, pp: 81--96, 2003.
[8] S.Y. Wang, C.L. Chou, C.H. Huang, C.C. Hwang, Z.M. Yang, C.C. Chiou, and C.C. Lin, "The Design and Implementation of the NCTUns 1.0 Network Simulator," Computer Networks, Vol. 42, Issue 2, June 2003, pp.175-197.
描述 碩士
國立政治大學
資訊科學學系
94753022
96
資料來源 http://thesis.lib.nccu.edu.tw/record/#G0094753022
資料類型 thesis
dc.contributor.advisor 張宏慶zh_TW
dc.contributor.advisor Jang, Hung Chinen_US
dc.contributor.author (Authors) 林暐清zh_TW
dc.contributor.author (Authors) Lin, Wei Chingen_US
dc.creator (作者) 林暐清zh_TW
dc.creator (作者) Lin, Wei Chingen_US
dc.date (日期) 2007en_US
dc.date.accessioned 8-Dec-2010 11:59:16 (UTC+8)-
dc.date.available 8-Dec-2010 11:59:16 (UTC+8)-
dc.date.issued (上傳時間) 8-Dec-2010 11:59:16 (UTC+8)-
dc.identifier (Other Identifiers) G0094753022en_US
dc.identifier.uri (URI) http://nccur.lib.nccu.edu.tw/handle/140.119/49465-
dc.description (描述) 碩士zh_TW
dc.description (描述) 國立政治大學zh_TW
dc.description (描述) 資訊科學學系zh_TW
dc.description (描述) 94753022zh_TW
dc.description (描述) 96zh_TW
dc.description.abstract (摘要) 本研究在減低Wimax mesh mode環境中media access階段會造成的delay現象。我們發現當subscriber station (SS)訊務繁忙時，競爭transmission opportunity (TO)以及3-way handshake的過程容易失敗，造成傳輸效率降低，封包的delay也會增加。同時我們也發現封包的延遲還來自minislot的不良配置。因為原始的Wimax mesh mode對於minislot的配置會造成預約過晚的問題，當預約時間被延長，資料就必須無條件的增加等待時間，因此我們將針對這些問題進行改善，降低在訊務繁忙的狀況下，傳輸效率低落的問題。

我們使用兩種方式來改善上述的問題，其一是由Bayer [4]所提出的動態調整holdoff指數(dynamic holdoff exponent)的方式，藉由調整holdoff指數的大小來縮短holdoff時間，以縮短傳輸延遲；另外，我們也提出一個以節點的臨接區域為配置基準(Neighborhood-Based Minislot Allocation, NBMA) 的方法，透過與其相鄰的節點交換訊息，優化minislot的配置。我們用這兩種方式減少IEEE 802.16中媒體存取階段所造成的傳輸延遲。

實驗結果顯示，在網路負載較輕的情況下，NBMA可以有效的將delay降低為原來的七分之一，改善幅度將近85%，抖動率(jitter)的部分亦有20%的改善，並略為提高傳輸效能8%左右；而當網路負載較重時，delay的改善程度仍有40%左右，jitter部分改善了12%，傳輸效能亦有6%的改善。證明了我們的方法確實可行，並且在改善delay方面有顯著的效果。		zh_TW
dc.description.abstract (摘要) IEEE 802.16 mesh network is a new environment of wireless network. It was designed as a self-organized, distributed scheduling, and multi-hop network. However, it is not robust enough to handle a heavy loading environment for lacking of QoS support. Our research is trying to reduce its media access delay, which comes from both TO (transmission opportunity) competition and improper minislot allocation. TO competition will extend the MSH-DSCH (mesh distributed scheduling) interval and slow down the exchanging speed of control message. Improper minislot allocation comes from the distributed scheduling of minislot. When a subscriber station (SS) allocates too much minislot for low-level traffic, it will defer the allocation of other neighbors’ high-level traffic.

We use Bayer’s [4] dynamic exponent to reduce holdoff time of SS, and speed up the exchange of control message. On the other hand, we design an “importance factor” (IM-factor) to score the importance of request. Through the exchange of IM-factor, SS and its neighbors will produce a threshold of IM-factor to filter the unimportant requests, and prevent minislot from being assigned too late.

In our experiments, the proposed methods can reduce 85% delay and 20% jitter, and increase bandwidth utility by 7%. It shows that our method in reducing transmission delay is pratical and effective.		en_US
dc.description.tableofcontents 第一章 緒論 8
1.1簡介 8
1.2研究動機與目的 10
1.3 IEEE 802.16的分散排程 11
1.3.1 Competition of Transmission Opportunity 12
1.3.2 Mesh mode signal 16
1.3.3 3-way handshake 18
第二章 相關研究 21
第三章 研究方法 25
3.1 問題描述 25
3.1.1 TO Interval 25
3.1.2 Minislot allocation 26
3.2 研究方法與原因 29
3.3 研究進行步驟 33
3.3.1 Delay-Sensitive Request and Virtual Node 34
3.3.2 Dynamic Holdoff Exponent 36
3.3.3 Request Scoring 39
3.3.4 Neighborhood distribution 49
第四章 模擬實驗 51
4.1 模擬環境 51
4.2 模擬實驗一 52
4.3 模擬實驗二 56
第五章 結論與未來研究 63
第六章 參考文獻 64		zh_TW
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dc.language.iso en_US-
dc.source.uri (資料來源) http://thesis.lib.nccu.edu.tw/record/#G0094753022en_US
dc.subject (關鍵詞) 網狀網路zh_TW
dc.subject (關鍵詞) 降低延遲zh_TW
dc.subject (關鍵詞) 媒體允入zh_TW
dc.subject (關鍵詞) WiMAXen_US
dc.subject (關鍵詞) mesh networken_US
dc.subject (關鍵詞) holdoffen_US
dc.subject (關鍵詞) delay reductionen_US
dc.subject (關鍵詞) media accessen_US
dc.subject (關鍵詞) IEEE 802.16en_US
dc.title (題名) IEEE 802.16網狀網路環境中降低媒體存取延遲研究zh_TW
dc.title (題名) Delay Reduction of Media Access for IEEE 802.16 Mesh Networken_US
dc.type (資料類型) thesisen
dc.relation.reference (參考文獻) [1] IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems, IEEE Std 802.16-2004. IEEE, 2004.zh_TW
dc.relation.reference (參考文獻) [2] M. Cao, W. Ma, Q. Zhang, and X. Wang, “Analysis of IEEE 802.16 Mesh Mode Scheduler Performance” IEEE Transaction on Wireless Communication, Vol. 6, NO. 4, April 2007.zh_TW
dc.relation.reference (參考文獻) [3] M. Cao, W. Ma, Q. Zhang, and X. Wang, “Modeling and Performance Analysis of the Distributed Scheduler in IEEE 802.16 Mesh Mode” Proc. ACM MobiHoc ’05, May 2005, pp.78-89.zh_TW
dc.relation.reference (參考文獻) [4] N. Bayer, B. Xu, V. Rakocevic, and J. Habermann, “Improving the Performance of the distributed Scheduler in IEEE 802.16 Mesh Networks”, Proceedings of Vehicular Technology Conference (IEEE VTC), Dublin, Ireland, April 2007.zh_TW
dc.relation.reference (參考文獻) [5] N. Bayer, B. Xu, V. Rakocevic, and J. Habermann, “Transmission Timing of Messages in IEEE 802.16 based Mesh Networks”, Proceedings of IEEE/VDE European Wireless, Athens, Greece, April, 2006.zh_TW
dc.relation.reference (參考文獻) [6] M.S. Kuran, B. Yilmaz, F. Alagoz, and T. Tugcu, “Quality of service in mesh mode IEEE 802.16 networks”, 14th International Conference on Software, Telecommunications and Computer Networks 2006, (SoftCOM `06), Split-Dubrovnik, Croatia, 2006, pp. 107-111.zh_TW
dc.relation.reference (參考文獻) [7] K. Wongthavarawat, and A. Ganz, “Packet Scheduling for QoS support in IEEE 802.16 broadband wireless access systems”, Int. J. Commun. Syst. Vol. 16, Issue 1, pp: 81--96, 2003.zh_TW
dc.relation.reference (參考文獻) [8] S.Y. Wang, C.L. Chou, C.H. Huang, C.C. Hwang, Z.M. Yang, C.C. Chiou, and C.C. Lin, "The Design and Implementation of the NCTUns 1.0 Network Simulator," Computer Networks, Vol. 42, Issue 2, June 2003, pp.175-197.zh_TW