無線隨意網路中以資料鏈結層為基礎實現多重連線技術

近年來，垂直式交遞技術成為一項熱門的研究領域，已經有許多無接縫垂直式交遞方式被提出。但是令人遺憾，大多數提出的方法都是在解決網際網路中移動所產生的交遞問題，較少關於無線隨意網路中的垂直式交遞技術研究。在這篇論文中，我們提出一個利用資料鏈結層多重連線的方式來實現無線隨意網路當中的垂直式交遞。基本的概念是將每一個實體的網路介面視為一個虛擬的網路節點，並且藉由附有權值的連線來與它所屬的移動裝置相互溝通。封包需要傳送時，會先送交於使用者所定義連線權重值最低的虛擬節點。而最後，相對應於該虛擬節點的實體網路介面將會根據路由表的資訊，把封包傳送至真正下一個實體網路節點。實驗的結果驗證了我們的方法在各程情況下，不但可以實現低延遲及低封包漏失，更能維護原有的傳輸連線。然而，在垂直式交遞過程中，我們的方法遭遇了轉換時期所帶來的問題，產生的原因是由於少許封包殘留於交遞前所使用的網路介面當中。我們提出一個清除殘留封包的改良機制來解決這個問題。實驗的結果顯示，在單距網路中，我們的方法搭配清除殘留封包的改良機制，可以大量縮短轉換的時期。此外，實驗的結果也證明移動裝置藉由我們的方法協助，可以更有效率的利用多個網路介面的頻寬。

關鍵字

交遞；無線隨意網路；多重連線

並列摘要

Since vertical handoff technology is a popular research area, numerous seamless vertical handoff works have been proposed recently. Unfortunately, most of them focus on Internet Mobility, and are not concerned how to provide a seamless vertical handoff approach in Mobile Ad-hoc NETworks (MANETs). In this thesis, we propose A Link-layer Multi-homing Approach (ALMA) for the vertical handoff in MANETs. The main idea of ALMA is to use a virtual interface to represent the mobile device itself and let each physical network interface act as a virtual neighbor node. That is, there is a weighted link between the virtual interface and each physical interface. The mobile device will choose the lowest weighted link, i.e., the physical interface, to deliver a packet. The results show that the ALMA is able to provide a seamless and smooth handoff service in MANET, i.e., our approach can not only achieve low latency and few packet losses, but maintain TCP connections in all experiments. Moreover, during the period of vertical handoff, we note that ALMA suffers the transition period problem that arises from the residual packets in the transmission queue of the old network interface. Hence, we proposed the Erasing Residual Packets (ERP) enhancement for ALMA to solve such problem. Our results illustrate that ALMA with ERP enhancement can reduce the length of the transition period significantly. Furthermore, the ALMA can be easily applicable to support an efficient multi-homing solution under the heterogeneous network environment.

並列關鍵字

handoff ； handover ； MANET ； ad-hoc ； multi-homing

參考文獻

[1] F. Siddiqui and S. Zeadally, “SCTP Multihoming Support for Handoffs across Heterogeneous Networks,” CNSR 2006, May 2006.

[4] A. C. Snoeren, and H. Balakrishnan. “An End-to-End Approach to Host Mobility,” In Proc. of MobiCom 2000.

[5] Mark Stemm, and Randy H. Katz. “Vertical Handoffs in Wireless Overlay Networks,” ACM Mobile Networking (MONET), 1998.

[7] S. Deering, and R. Hinden, “Internet Protocol, Version 6 (IPv6) Specification,” RFC 2460, IETF, Dec. 1998.

[8] D. Maltz, and P. Bhagwat, “MSOCKS: An architecture for transport layer mobility,” In Proc. of IEEE Infocom, p.p. 1037-1045, March 1998.

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無線隨意網路中以資料鏈結層為基礎實現多重連線技術

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