臺灣博碩士論文加值系統

未來4G網路的願景是整合現今已經發展的各式無線網路技術，諸如UMTS、WiFi、WiMAX等。因此，行動終端裝置為了要能存取不同的無線網路技術，勢必要裝備多種不同的網路裝置，因而衍生出一個議題，便是如何隨時選擇一個對使用者而言是最好的網路。
在本論文中，我們提出一個以MIH（Media Independent Handover）資訊服務做為協助，搭配使用者設定檔的機制來選擇網路。MIH是由IEEE所提出，為了促進在不同的802網路系統之間更容易地進行換手。使用者藉由設定檔可以設定所需求的網路環境，進而使網路選擇機制可以選到更適合的環境。除此之外，我們設計了MIH資訊服務，來提供行動終端裝置在適當的時候可以取得當前的網路環境資訊，例如網路傳輸延遲（end to end delay）與末端網路的訊框錯誤率（frame error rate）。本論文以規則過濾的方式（rule-based）來篩選出一個最好的網路。最後，我們根據所提出的機制，設計了個案學習（case study）來驗證本論文的可行性。模擬結果顯示，本論文提出的機制是可行的。

The vision of the fourth-generation network is to integrate different access technologies such as UMTS, WiFi, WiMAX, etc. In order to access different access technologies, it’s a trend that mobile nodes will be equipped with multiple interfaces. Thus, an important issue is how to choose an appropriate access network for the user all the time.
In this thesis, we proposed a user profile based network selection algorithm with the assistance of the MIH (Media Independent Handover) information service. The MIH is proposed by IEEE to facilitate handover between 802 networks whether or not they are of different media types, including both wired and wireless. In order to assist mobile nodes in selecting preferred networks, besides the definition of the user profiles, we also design an information service to support network selection for mobile nodes. A rule-based network selection algorithm is proposed to integrate the user profiles and information service. Finally, we used the WiFi VoIP as a case study by the proposed scheme. As the simulation result shows, our proposed scheme works well as expected.

Title Page I
Abstract (Chinese) II
Abstract (English) III
Acknowledgement (Chinese) IV
Index V
Figure Index VI
Table Index VIII
1. Introduction 1
1.1. Background 1
1.2. Motivation 1
1.3. Approach 2
1.4. Contribution 3
1.5. Thesis organization 3
2. Related Work 4
2.1. Network Selection 4
2.2. MIH 6
3. User Profile-Based Network Selection 8
3.1. Network Selection Procedure 8
3.2. MIH IS Architecture 9
3.3. User Profile 10
3.4. Network Selection Design 12
3.4.1. Information Server 12
3.4.2. Message Flows between MN and IS 13
3.4.3. Network Selection algorithm 14
4. Case Study: WiFi VoIP 17
4.1. WiFi VoIP User Profile 17
4.2. Simulation Environment 17
4.3. Simulation Design 20
4.4. Simulation Analysis 20
4.4.1. Simulation for the priority of QoS factor 20
4.4.2. VoIP simulation – scenario 1 22
4.4.3. VoIP simulation – scenario 2 24
4.4.4. VoIP simulation – scenario 3 28
5. Conclusion and Future Work 32
References 33

[1]E. Gustafsson and A. Jonsson, “Always Best Connected,” in Wireless Communications, vol. 10, issue 1, pp. 49-55, Feb. 2003
[2]S. Ohzahata, S. Kimura, and Y. Ebihara, “Adaptive handoff algorithm for efficient network resource utilization,” in 17th International Conference on Advanced Information Networking and Applications, pp. 743-748, 27-29 Mar. 2003.
[3]Y. Gwon, D. Funato, A. Takeshita, "Adaptive approach for locally optimized IP handoffs across heterogeneous wireless networks," 4th International Workshop on Mobile and Wireless Communications Network, 9-11 Sept. 2002, pp. 475-479.
[4]M. Ylianttila et al., "Optimization Scheme for Mobile Users Performing Vertical Handoffs between IEEE 802.11 and GPRS/EDGE networks," Proc. Globecom2001, pp. 25-29, Nov. 2001
[5]V. Gazis, N. Alonistioti, L. Merakos, “Toward a generic ‘always best connected’ capability in integrated WLAN/UMTS cellular mobile networks (And Beyond),” IEEE Wireless Communication, vol. 12, issue 3, pp. 20-29, Jun. 2005
[6]H.J. Wang, R.H. Katz and J. Giese, “Policy-enabled handoffs across heterogeneous wireless networks,” in Proc. WMCSA ''99 on Mobile Computing Systems and Applications, pp. 51-60, 25-26 Feb. 1999
[7]Fang Zhu and J. McNair, "Optimizations for vertical handoff decision algorithms," in Wireless Communications and Networking Conference, vol.2, pp. 867-872, 21-25 Mar. 2004
[8]Ajay Rajkumar, “Media Independent Handover Services,” IEEE draft, Jul. 2005
[9]J. McNair, Z. Fang, “Vertical handoffs in fourth-generation multinetwork environments,” IEEE Wireless Communication, vol. issue 3, pp. 8-15, Jun. 2004
[10]Cheng Wei Lee, Li Ming Chen, Meng Chang Chen, Yeali Sunny Sun, "A framework of handoffs in wireless overlay networks based on mobile IPv6," in IEEE Journal on Selected Areas in Communications, vol. 23, issue 11, pp. 2118-2128, Nov. 2005
[11]Ho Chan, Pingyi Fan, Zhigang Cao, "A utility-based network selection scheme for multiple services in heterogeneous networks," in International Conference on Wireless Networks, Communications and Mobile Computing, vol. 2, pp. 1175-1180, 13-16 Jun. 2005
[12]Ruay-Shiung Chang and Shing-Jiuan Leu, "Handoff ordering using signal strength for multimedia communications in wireless networks," in IEEE Transactions on Wireless Communications, vol. 3, issue 5, pp. 1526-1532, Sep. 2004
[13]R. Stewart et al., “Stream Control Transmission Protocol,” IETF RFC 2960, Oct. 2000.
[14]R. Stewart et al., “Stream Control Transmission Protocol (SCTP) Dynamic Address Reconfiguration,” in IETF Internet Draft, June 10, 2004, draft-ietf-tsvwg-addip-sctp-09.txt.
[15]L. Ma, F. Yu, V.C.M. Leung and T. Randhawa, “A new method to support UMTS/WLAN vertical handover using SCTP”, IEEE Wireless Communications, vol. 11, no. 4, pp. 44-51, Aug. 2004.
[16]NS2 (Network Simulator - version 2), http://www.isi.edu/nsnam/ns/
[17]Wen-Tsuen Chen, Yen-Yuan Shu, “Active application oriented vertical handoff in next-generation wireless networks,” in Wireless Communications and Networking Conference, vol. 3, pp. 1383-1388, 13-17 Mar. 2005
[18]An IEEE 802.11e EDCA and CFB Simulation Model for ns-2, http://www.tkn.tu-berlin.de/research/802.11e_ns2/