臺灣博碩士論文加值系統

在本論文中，為了改善在IEEE 802.11網路中因換手(handoff)所產生的問題，例如：過長的換手延遲(handoff latency)與網路訊息的壅塞(message congestion)等等，都會影響整個網路的運作效率及安全性；所以我們提出了主從式合作機制(client-server cooperative mechanism)以達到改善的目的和解決相關的問題。

在主從式合作機制中，我們會先利用存在於網路端的行動中心(mobility center，簡稱MC)對網域內所有行動節點(mobile node，簡稱MN)過去經過的無線存取點(access point，簡稱AP)所獲得的相關資訊進行紀錄，使得未來MN可以針對能提供較高服務品質(quality of service，簡稱QoS)的AP來進行handoff；另一方面在用戶端的MN中也會將局部的資訊保存於快取暫存區(cache)中，加快往後執行handoff的速度以便改善換手延遲的情形。

In this paper, we propose a new mechanism to obviate handoff delay and message congestion for fast handoff process in 802.11 networks. Since the utilization of wireless local area networks (WLAN) and security may degrade due to those problems, we take advantage of client-server cooperative mechanism to improve related issues.

We use mobility center (MC), to record related information about access point (AP) which mobile node (MN) had handoff before. So, MN can quickly select AP which has better quality of service (QoS) to execute handoff in the future. Besides these, MN also keeps local information about AP in cache to speed up the coming handoff. In this way, the above-mentioned problem can be improved well.

論文摘要 ............................................... IV
Abstract .................................................. V
誌謝 ................................................... VI
目錄 .................................................. VII
圖目錄 .................................................. X
表目錄 ................................................ XII

第一章 導論 1
1.1 研究背景 ........................................ 1
1.2 研究動機與目的 .................................. 2
1.3 各章摘要 ........................................ 3
第二章 IEEE 802.11系統及相關換手程序 5
2.1 IEEE 802.11系統概述 .............................. 5
2.1.1 IEEE 802.11系統下的三項標準 ............... 5
2.1.2 IEEE 802.11系統下的媒介存取控制層 ......... 8
2.2 IEEE 802.11換手程序 ............................. 11
2.2.1 IEEE 802.11系統下的無線區域網路架構 ...... 11
2.2.2 IEEE 802.11系統下的管理訊框 .............. 13
2.2.3 IEEE 802.11系統下的換手流程 .............. 15
第三章 相關研究之探討 24
3.1 改善第二層換手延遲的方法 ....................... 24
3.1.1 實際量測後對於換手延遲的分析 ............ 24
3.1.2 選擇性掃描演算法 ........................ 30
3.2 第三層的行動管理策略 ........................... 34
3.2.1 巨觀移動下的管理方式 .................... 35
3.2.2 微觀移動下的管理方式 .................... 40
3.2.3 比較與分析 .............................. 47
第四章 主從式合作機制 50
4.1 相關系統架構及運作方式 ......................... 50
4.2 特性分析........................................ 59
第五章 模擬結果與效能分析 62
5.1 模擬環境介紹 ................................... 62
5.2 結果與分析 ..................................... 64
第六章 結論與未來展望 70

參考文獻 ............................................... 72
作者簡介 ............................................... 77

[1] IEEE, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” IEEE Standard 802.11, 1999.
[2] V. Nee, “New High-Rate Wireless LAN Standards,” IEEE Communications Magazine, vol. 37, pp. 82–88, Dec. 1999.
[3] D. Corner, J. Lin, and V. Russo, “An Architecture for a Campus-Scale Wireless Mobile Internet,” Tech. Rep. CSD-TR 95-058, Purdue University, Computer Science Department.
[4] A. Hills and D. Johnson, “A Wireless Data Network Infrastructure at Carnegie Mellon University,” IEEE Personal Communications, vol. 3, pp. 56–63, Feb. 1996.
[5] P. Bahl, A. Balachandran, and S. Venkatachary, “Secure Wireless Internet Access in Public Places,” in Proceedings of IEEE International Conference on Communications 2001, Jun 2001.
[6] S.Shin, A.Rawat, and H.Schelzrinne, “Reducing MAC Layer Handoff Latency in IEEE 802.11 Wireless LANs” Proceedings of ACM MobiWac 2004.
[7] IEEE, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, Reference number ISO/IEC 8802-11:1999(E), IEEE Std 802.11, 1999 edition, 1999.
[8] J. Yu, S. Choi and J. Lee, “Enhancement of VoIP over IEEE 802.11 WLAN via Dual Queue Strategy", International Conference on Communications, 2004.
[9] IEEE, Supplement to Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Higher-speed Physical Layer Extension in the 2.4 GHz Band, IEEE Std. 802.11b-1999, 1999.
[10] J. Geier. Understanding 802.11 frame types. Technical report, Jupitermedia Corporation, Aug 2002.
[11] A. Mishra, M. Shin, and W. Arbaugh, “An empirical analysis of the IEEE 802.11 MAC layer handoff process,” ACM Computer Communications Review, vol. 33, no. 2, Apr. 2003.
[12] M. Shin, A. Mishra, and W. Arbaugh, “Improving the latency of 802.11 hand-offs using neighbor graphs,” in Proceedings of the ACM MobiSys Conference, Boston, MA, Jun 2004.
[13] A. Mishra, M. Shin, and W. A. Arbaugh, “Pro-active Key Distribution using Neighbor Graphs,” IEEE Wireless Communications Magazine, Feb. 2004.
[14] IEEE Std 802.11f. IEEE Recommended Practice for Multi-Vendor Access Point Interoperability via an Inter-Access Point Protocol Across Distribution Systems Supporting IEEE 802.11 Operation. Technical report, IEEE, Jul. 2003.
[15] A. Mishra, M. Shin, and W. A. Arbaugh, “Context caching using neighbor graphs for fast handoffs in a wireless network,” In Proceedings of IEEE Conference on Computer Communications (INFOCOM), pages 351-361, Mar. 2004.
[16] I. F. Akyildiz, J. Xie, and S. Mohanty, “A survey of mobility management in next-generation all-IP-based wireless systems,” In Wireless Communications, IEEE (See also IEEE Personal Communications), pages 16–28, Aug. 2004.
[17] Perkins, C., “IP mobility support for IPv4”, RFC 3344 IETF, Aug 2002.
[18] Johnson, D., Perkins, C., Arkko, J., "Mobility Support in IPv6", RFC 3775 IETF, Jun 2004.
[19] C. E. Perkins and D. B. Johnson, “Route Optimization in Mobile IP,” Internet draft, Sep. 2001, work in progress.
[20] A. T. Campbell et al., “Comparison of IP Micromobility Protocols,” IEEE Wireless Commun., Feb. 2002, pp. 72–82.
[21] E. Gustafsson, A. Jonsson, and C. E. Perkins, “Mobile IPv4 Regional Registration,” Internet draft, Jun 2004, work in progress.
[22] Soliman, H., Castelluccia, C., El-Malki, K., Bellier, L., "Hierarchical MIPv6 mobility management", RFC 4140 IETF, Aug 2005.
[23] A. Misra et al., “IDMP-Based Fast Handoffs and Paging in IP-Based 4G Mobile Networks,” IEEE Commun. Mag., Mar. 2002, pp. 138–45.
[24] A. T. Campbell et al., “Design, Implementation, and Evaluation of Cellular IP,” IEEE Pers. Commun., Aug. 2000, pp. 42–49.
[25] R. Ramjee et al., “HAWAII: A Domain-Based Approach for Supporting Mobility in Wide-Area Wireless Networks,” IEEE/ACM Trans. Net., vol. 10, no. 3, Jun 2002, pp. 396–410.
[26] F. M. Chiussi, D. A. Khotimsky, and S. Krishnan, “Mobility Management in Third-Generation All-IP Networks,” IEEE Commun. Mag., Sep. 2002, pp. 124–35.
[27] 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.
[28] General characteristics of international telephone connections and international circuits. ITU-TG, 114, 1998.