臺灣博碩士論文加值系統

近年來，各式的無線網路存取技術快速的發展。而在包含了數種存取技術(如：802.11, 802.16 和 3G/UMTS等) 的網路，我們稱為「異質無線網路」。在這樣的異質的無線網路環境中，「垂直漫遊」是一項可以讓使用者在使用不同存取技術的網路間移動的技術。雖然垂直漫遊可以讓使用者在異質網路中使用不同的存取技術來獲得網路服務，但是，過多垂直漫遊的切換會造成一些負面的影響，如：漫遊的時間延遲過長，連線可能被中斷，和較低的網路使用率。此外，在漫遊的過程中，網路頻寬的快速變化會造成TCP傳輸率不佳。因此在本篇論文中，我們提出了一個高效率的垂直漫遊方法，利用訊號強度的預測來降低不必要的垂直漫遊，以及一個跨協定的漫遊方法，透過跨協定的機制讓TCP可以適時的對漫遊來調整控制視窗，以提昇TCP在異質無線網路環境中的傳輸率。數據結果顯示我們提出的高效率的垂直漫遊方法在不降低網路使用率的情況下可以得到較低的漫遊次數以及良好的grade of service，另外透過跨協定漫遊方法可以使TCP Reno與TCP NewReno得到比TCP Reno與TCP NewReno更好的效能。

Recently, many wireless access techniques are developed rapidly. The wireless networks which consist of several kinds of wireless access techniques, such as 802.11, 802.16 and 3G/UMTS, etc., are formed heterogeneous wireless networks. In such heterogeneous wireless network, vertical roaming allows user moving between wireless networks which have different access techniques. However, too much unnecessary vertical roaming may result in some drawbacks, including long roaming delay, connection dropping and low utilization. Besides, the fast changes of bandwidth cause by vertical roaming will lead to the low performance of TCP. Therefore, in this paper we proposed an efficient vertical roaming approach that uses the RSS prediction to reduce the unnecessary vertical roaming, and a cross layer-based approach that uses cross layer mechanism to adjust the TCP when vertical roaming is performed to improve the performance of TCP in heterogeneous wireless networks. Numerical results show that the proposed efficient vertical roaming approach yields less number of roams and low grade of service while yielding competitive utilization. The proposed cross layer-based approach improves the performance of TCP Reno and TCP NewReno.

Chapter 1 Introduction 5
Chapter 2 Network model 12
Chapter 3 Efficient vertical roaming approach 15
3-1. The importance of hysteresis and RSS prediction 16
3-2. Polynomial Regression-Based RSS Prediction 20
3-3. Optimal Network Selection 27
Chapter 4 Cross layer-based predictive bandwidth for increase TCP good put 32
Chapter 5 Message flow and delay analysis 36
5-1. Message Flow in Vertical Roaming Approach 37
5-2. Delay Analysis of Message Flows in Vertical Roaming Approach 40
Chapter 6 Numerical results 45
Chapter 7 Conclusions and future works 56
References 57

[1]IEEE Std. 802.11.
[2]IEEE Std. 802.16.
[3]3GPP, http://www.3gpp.org .
[4]G. P. Pollini, “Trends in Handover Design,” IEEE Communications Magazine, Vol. 34, Issue 3, pp. 82–90, March 1996.
[5]Marcello Cinque, Domenico Cotroneo, and Stefano Russo, “Achieving all the time, everywhere access in next-generation mobile networks,” ACM SIGMOBILE Mobile Computing and Communications Review, Vol. 9, Issue 2, Apr. 2005.
[6]P. Marichamy, S. Chakrabarti, and S.L. Maskara, “Performance evaluation of roaming detection Schemes,” TENCON 2003, Vol. 2, pp. 643–646, Oct. 2003.
[7]Hongyan Bing, Chen He, and Lingge Jiang, “Performance analysis of vertical handover in a UMTS-WLAN integrated network,” Personal, Indoor and Mobile Radio Communications, Volume 1, pp. 187-191, Sep. 2003.
[8]Janise Mcnair and Fang Zhu, “Vertical Roamings in Fourth-Generation Multinetwork Environments,” IEEE Wireless Communications, Vol. 11, Issue 3, pp. 8–15, June 2004.
[9]Fang Zhu and J. McNair, “Optimizations for Vertical Roaming Decision Algorithms,” IEEE Wireless Communications and Networking Conference 2004, Vol. 2, pp. 867 – 872, March 2004.
[10]Qizn Zhang, Chuanxong Guo, Zihua Guo, and Wenwu Zhu, “Efficient Mobility Management for Vertical Roaming between WWAN and WLAN,” IEEE Communication Magazine 2003, Vol. 41, Issue 11, pp. 102–108, Nov. 2003.
[11]Chuanxong Guo, Zihua Guo, Qizn Zhang, and Wenwu Zhu, “A Seamless and Proactive End-to-End Mobility Solution for Roaming Across Heterogeneous Wireless Networks,” IEEE Journal on Selected Areas in Communications, Vol. 22, Issue 5, pp. 834–848, June 2004.
[12]Wen-Tsuen Chen, Ten-Yuan Shu, “Active Application Oriented Vertical Roaming in Next-Generation Wireless Networks,” IEEE Wireless Communications and Networking Conference, Vol. 3, pp. 1383–1388, March 2005.
[13]Ben-Jye Chang and Shu-Yu Lin, “Mobile IPv6-based Efficient Vertical Roaming Approach for Heterogeneous Wireless Networks,” Wireless Communications and Mobile Computing, Vol. 6, Issue 5, 2006.
[14]J. Postel., “Transmission Control Protocol,” IETF RFC 793, Sep. 1981.
[15]Rajeev Koodli, “Fast Handovers for Mobile IPv6,” IETF Internet-Draft, Oct. 2004.
[16]Ting-Cheng Chang, Kuu-Li Wen, and Mei-Li You, “The Study of Regression Based on Grey System Theory,” IEEE International Conference on Systems, Man, and Cybernetics, Vol. 5, pp. 4307–431, Oct. 1998.
[17]陳恆州、曾玲慈，「應用指數化灰生成於低階多項式預測系統之研究」，第三屆灰色系統理論與應用研討會論文集，1998，第479頁。
[18]Steven C. Chapra and Raymond P. Canale, “Numerical Methods for Engineers,” McGraw-Hill, 2002.
[19]R. Gawlick, A. Kamath, S. Plotkin, and K. Ramarkrishnan, “Routing and Admission Control in General Topology Networks,” Technical report STAN-CS-TR-95-1548, Stanford University, 1995.
[20]Borodin Allan and Ran El-Yaniv, “Online computation and competitive analysis,” Cambridge University Press, 1998.
[21]L. Zhang, M. Andrews, W. Aielo, S. Bhatt, and K. R. Krishnan, “A Performance Comparison of Competitive On-line Routing and State-Dependent Routing,” IEEE GLOBECOM’97, pp. 1813-1819, Nov. 1997.
[22]Q. Wang, M. A. Abu-Rgheff, and A. Akram, “Design and Evaluation of an Integrated Mobile IP and SIP Framework for Advanced Handoff Management,” IEEE ICC 2004, Vol. 7, pp. 3921-3925, June 2004.
[23]D. Johnson, C. Perkins, and J. Arkko, “Mobility Support in IPv6,” IETF RFC 3775, June 2004.
[24]N. Banerjee, Wei Wu, and S. K. Das, “Mobility Support in Wireless Internet,” IEEE Wireless Communications, Vol. 10, Issue 5, pp. 54–61, Oct. 2003.
[25]M. Allman, V. Paxson, and W. Stevens, “TCP Congestion Control,” IETF RFC 2581, April 1999.
[26]M. Ylianttila, “Vertical Handoff and Mobility – System Architecture and Transition Analysis,” Doctoral thesis, Department of Electrical and Information Engineering, University of Oulu, 2005
[27]Hyun-Ho Choi, Osok Song, and Dong-Ho Cho, ”A Seamless Handoff Scheme for UMTS-WLAN Interworking,” IEEE Global Telecommunications Conference 2004, Vol. 3, pp. 1559–1564, Nov. 2004.
[28]A. Majlesi and B. H. Khalaj, “An Adaptive Fuzzy Logic Based Roaming Algorithm For Interworking Between WLANs and Mobile Networks,” Personal, Indoor and Mobile Radio Communications, Vol. 5, pp. 2446–2451, Sep. 2002.
[29]S. Floyd and T. Henderson, “The NewReno Modification to TCP''s Fast Recovery Algorithm,” IETF RFC 2582, April 1999.
[30]S. Floyd, T. Henderson, and A. Gurtov, “The NewReno Modification to TCP''s Fast Recovery Algorithm,” IETF RFC 3782, April 2004.
[31]W. Stevens, “TCP Slow Start, Congestion Avoidance, Fast Retransmit, and Fast Recovery Algorithms,” IETF RFC 2001, Jan. 1997.
[32]Network Simulator (NS-2), http://www.isi.edu.nsnam/ns/