SIP-BASED MOBILE VPN AND MOBILITY MANAGEMENT IN WiMAX NETWORKS

In this thesis, we focus on two critical issues in all-IP wireless networks: mobile virtual private networks and mobility management in WiMAX networks. We first study the IETF’s mobile virtual private network(MVPN) and propose an alternative SIP-based MVPN. Because the proposed architecture is based on SIP, the problems inherited from Mobile IP are not problems in our architecture. In addition, there is no need to tunnel a packet three times as that in IETF MVPN. In this thesis, we also propose analytical models to evaluate and compare the performance of the proposed SIP-based MVPN with the IETF MVPN. The results show that the proposed SIP-based MVPN can reduce packet delivery cost significantly. It is especially suitable for real-time applications. Mobility management is a critical issue for wireless networks, especially for highspeed data transmissions in next-generation wireless systems. WiMAX forum is developing and standardizing the WiMAX Forum Network Architecture, which is regarded as one of the next-generation wireless networks. In the architecture, WiMAX Forum has defined a twotiered mobility management to reduce handover delay and avoid service disruption. However, it leads to another problem: when to perform ASN GWrelocation? The standards only define the ASN GWrelocation procedures without specifying when the ASN GWrelocation should be performed. It is left for vendors and operators to develop their own proprietary solutions. In this thesis, we propose an algorithm which incorporates traditional admission control algorithms and Wiener Process to determine when to carry out ASN GW relocation. We further develop an analytical model to analyze the proposed algorithm. Simulations are also conducted to evaluate the performance of the proposed algorithm. The results show that the proposed algorithm can improve the performance significantly in terms of blocking probability, dropping probability, average serving rate, and average signaling overhead.

關鍵字

SIP協定；移動式虛擬私有網路；移動管理；全球互通微波存取網路；允入控制；統計與隨機程序；無線網路；效能分析

並列摘要

在本論文中，我們將探討全IP無線網路中的關鍵性議題：移動式虛擬私有網路與WiMAX網路之移動管理。首先，我們研究由IETF所提出的移動式虛擬私有網路(MVPN)，並且提出以SIP為基礎的MVPN (SIP-based MVPN)為替代方案。由於所提出的架構是以SIP為基礎，原本由Mobile IP所衍生的問題將不存在於本系統之中。另外，在IETF MVPN中，傳送封包需要經過三次Tunneling，本方法則不需要。在本論文中，我們也提出分析架構，並且檢視與比較SIP-based MVPN與IETF MVPN的網路效能。實驗結果顯示我們所提出的SIP-based MVPM可以顯著地降低封包傳遞成本。尤其是針對即時性的應用，本方法特別適合。在無線網路中，移動管理是另一個重要問題，尤其是針對下一代無線系統的高速資料傳輸。全球互通微波存取(WiMAX)討論會正在發展被視為下一代無線通訊網路，稱之為WiMAX Forum Network Architecture，並且制定相關標準。在此網路架構中，為了降低換手延遲和服務中斷，WiMAX討論會定義了兩階層的移動管理機制。然而，此移動機制卻產生另一個問題：何時啟動Access Service Network閘道器(ASN GW)的置換？標準文件只有定義ASN GW置換的程序但沒有說明何時啟動。此問題留待製造商或系統業者發展專屬的方法。在本論文中，我們提出演算法，透過整合傳統的允入控制和Wiener Process來決定何時啟動ASN GW置換程序。我們更進一步提出分析模型來分析所提出的方法，並且建構多種模擬來檢視演算法的效能。結果顯示所提出的方法明顯地改善了使用者被阻塞或中斷的機率、平均服務率及平均訊號成本負擔等效能指標。

並列關鍵字

SIP protocol ； mobile VPN ； mobility management ； WiMAX networks ； admission control ； statistics and stochastic process ； wireless networks ； performance analysis

參考文獻

[4] Y.-W. Liu, J.-C. Chen, and L.-W. Lin, “Dynamic external home agent assignment in mobile VPN,” in Proc. of IEEE Vehicular Technology Conference, (Los Angles, CA), pp. 3281–3285, Sept. 2004.

[5] J.-C. Chen, Y.-W. Liu, and L.-W. Lin, “Mobile virtual private networks with dynamic MIP home agent assignment,” Wireless Communications and Mobile Computing, Wiley, vol. 6, pp. 601–616, Aug. 2006.

[8] J.-C. Chen and T. Zhang, IP-Based Next-Generation Wireless Networks. Wiley, Jan. 2004. http://www.cs.nthu.edu.tw/˜jcchen/book.html.

[10] D. Sisalem, J. Kuthan, and S. Ehlert, “Denial of service attacks targeting a SIP VoIP infrastructure: attack scenarios and prevention mechanisms,” vol. 20, no. 5, pp. 26–31, 2006.

[11] S. Salsano, L. Veltri, and D. Papalilo, “SIP security issues: The SIP authentication procedure and its processing load,” vol. 16, pp. 38–44, Nov. 2002.

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SIP-BASED MOBILE VPN AND MOBILITY MANAGEMENT IN WiMAX NETWORKS

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