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結論

在文檔中 中 華 大 學 (頁 111-114)

換手時造成的 IP 封包遺失與 TCP 傳送失序的問題,一直都是降低換手效能 的主要因素,而部份使用通道技術的換手機制,大都減少了 IP 封包遺失的問題,

但卻沒有考慮 TCP 傳送失序的問題。

在本篇論文中我們利用 Freeze-TCP 的技術來暫停換手時的 TCP 封包傳送,

無論使用 MIPv6、HMIPv6(Micro/Macro)、FMIPv6(Predictive/Reactive)或者 MMS 換手機制,都能減少換手時產生的 IP 封包遺失與 TCP 傳送失序的問題,避免兩 者的無效 TCP 封包傳送,節省無謂的頻寬浪費,並減少行動節點與網路裝置無 謂的負載,也更能提早回復正確的 TCP 傳送順序。

而 Freeze-TCP 的機制更完全不用更改 TCP 接收端,不用額外佈署網路裝 置,也不需要更改既有的換手機制,也沒有複雜的運作程序,只需在行動節點上 的 TCP 傳送端做些小更改,適時發送 TCP 標準中的零接收視窗大小廣播來凍結 (FreezeOn)對方的傳送,與換手快結束前適時的發送一個包含原來接收視窗大小 值的 TCP 告知(FreezeOff),即可回復原來的 TCP 傳送順序,而不用等到行動節 點完成換手後,等到收到對方第一個 TCP 封包才發現 TCP 失序。

結合 Freeze-TCP 的換手能以極低的成本換得更多益處,且與現有的換手機 制共同運作不互相干擾,相容於既有的行動網路架構下,能幫助行動節點更快、

更平順的完成換手程序。

近年來一種新的傳輸層通訊協定 DCCP[23]被提出,希望能在網路頻寬足夠 且穩定時,能夠追求可靠性的傳輸,而在網路頻寬較差的環境下,犧牲可靠性進 而追求即實性的傳輸,依網路的擁塞情況來決定傳送形式,本篇論文是以結合 Freeze-TCP 來增進 TCP 連線的傳送效益,未來我們可能研究如何在 DCCP 上,

實現結合如同 Freeze 的換手方式,使追求可靠性與即時性之間求得平衡的 DCCP,能在換手時維持更好的傳送效益。

參考文獻

[1]. IEEE Std. 802.11a, “Part 11: Wireless LAN Medium Access Control (MAC)

and Physical Layer (PHY) specifications: High-speed Physical Layer in the 5 GHZ Band,” IEEE Std. 802.1la-1999, 1999.

[2]. IEEE Std. 802.11b, “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. 802.1lb-1999, 1999.

[3]. IEEE Std. 802.11g, “Part 11: Wireless LAN Medium Access Control (MAC)

and Physical Layer (PHY) specifications: Amendment 4: Futher Higher Data Rate Extension in the 2.4 GHz Band,” IEEE Std. 802.1lb-1999, 1999.

[4]. IEEE 802.11n, Draft 7.0 “Wireless LAN Media Access Control (MAC) and

Physical Layer (PHY) Specifications: Enhancements for Higher Throughput,”

November. 2008.

[5]. WiMAX Forum, “Mobile WiMAX — Part I/II: A Technical Overview and

Performance Evaluation,” http://www.wimaxforum.org/, Feb. 2006.

[6]. 3G PP, “UTRA-UTRAN Long Term Evolution (LTE) and 3GPP System

Architecture Evolution (SAE),” http://www.3gpp.org/, Oct. 2006.

[7]. D. Johnson, C. Perkins, and J. Arkko, “Mobility Support in IPv6,” RFC 3775,

IETF, Jun. 2004.

[8]. H. Soliman, C. Castelluccia, K. ElMalki, and L. Bellier, “Hierarchical Mobile

IPv6 (HMIPv6) Mobility Management,” RFC 5380, IETF, Oct. 2008.

[9]. Wei Kuang Lai and Jung Chia Chiu, “Improving handoff performance in

wireless overlay networks by switching between two-layer IPv6 and one-layer

IPv6 addressing,” IEEE Journal on Selected Areas in Communications, Vol. 23

No. 11 Pages:2129 – 2137, Nov. 2005.

[10]. R. Koodli, “Mobile IPv6 Fast Handovers,” RFC 5268, IETF, Jun. 2008.

[11]. T. Goff, J. Moronski, D. S. Phatak, and V. Gupta, “Freeze-TCP: a true

end-to-end TCP enhancement mechanism for mobile environments,”

Proceedings of Nineteenth Annual Joint Conference of the IEEE Computer and Communications Societies(INFOCOM 2000), Vol. 3 Pages:1537 - 1545, Mar.

2000.

[12]. Huai-Jen Liu and Chih-Hao Wang, “Transparent IP Mobility Management,”

Proceedings of Future Generation Communication and Networking(FGCN 2007), Vol. 1 Pages:374 – 377, 6-8 Dec. 2007.

[13]. S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdhury, and B. Patil, “Proxy

Mobile IPv6,” RFC 5213, IETF, Aug. 2008.

[14]. J. Kempf, “Problem Statement for Network-Base Localized Mobility

Management(NETLMM),” RFC 4830, IETF, Apr. 2007.

[15]. Huu-Nghia Nguyen and Christian Bonnet, “Scalable Proxy Mobile IPv6 for

Heterogeneous Wireless Networks,” Proceedings of the International Conference on Mobile Technology, Applications, and Systems, Article No. 64,

Sep. 2008.

[16]. Jae-Woo Kwon, Hee-Dong Park, and You-Ze Cho, “An efficient TCP

mechanism for Mobile IP handoffs,” Proceedings of IEEE Region 10 International Conference on Electrical and Electronic Technology(TENCON 2001), Vol. 1 Pages:278 - 281, Aug. 2001.

[17]. Seung Beom Lee, Kyeong Hur, Jongsun Park, and Doo-Seop Eom, “A Packet

Forwarding Controller for Mobile IP-based Networks with Packet Buffering,”

IEEE Transactions on Consumer Electronics, Vol. 55 Pages:1344-1350, Aug.

2009.

[18]. Robert Hsieh, Zhe Guang Zhou, and Aruna Seneviratne, “S-MIP: A Seamless

在文檔中 中 華 大 學 (頁 111-114)

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