臺灣博碩士論文加值系統

異質無線網路環境是由不同特性的無線網路所構成，包括了涵蓋區域、行動能力以及頻寬等差異。現今許多研究依循網際網路層次觀點達成異質無線網路垂直換手服務。在可以預見的未來無線行動網際網路環境將會是一個多元且豐富的異質型態。傳統的位置管理系統主要是以區域的概念來呼叫終端使用者，倘若以此概念應用於階層式異質網路，將導致過多的信號與資源浪費。同質網路換手管理機制，一般是根據訊號強弱來判斷換手與否，於階層式異質網路環境中必須考量的換手觸發點將更多更複雜。
基於無縫式換手服務及位於無所不在的網路資源環境的需求下，我們提出了適於異質無線網路行動管理機制來克服不必要的呼叫信令與資源保留。本論文提出的適性準則分為兩個部份。第一個部份根據終端使用者位置更新來評估使用者的行動速度，此訊息將提供系統設計動態管理機制。第二個部份根據終端用戶的應用頻寬需求來動態擇選最適合的網路，這機制亦可以避免不必要的換手。
從實驗結果顯示，我們提出的機制相較於傳統方式，將可以有效降低近40%的呼叫信令，以及呼叫延遲性。另一方面將可以提供較佳的換手觸發條件以及換手時間點。從模擬結果中顯示，我們的機制可以有效解決異質網路中行動管理的問題。

A heterogeneous wireless network is made up by variety of property wireless networks, include wide and local area, high and low mobility, and different bandwidth support. More and more researches try to achieve seamless vertical handoff between WWAN and WLAN in accordance with all layers. It is anticipated that the future wireless mobile Internet will be a pluralistic wireless environment. Majority traditional location management schemes are based on paging mobile terminal within each domain area. These schemes generate unnecessary signaling overheads. In homogeneous wireless network, handoffs are always triggered at “handoff boundary” by detecting signaling strength. Whereas in the heterogeneous wireless network, the number of handoff triggers should be considered.
In this thesis, we proposed an adaptive mobility management scheme to decrease paging signaling and resource reservation. The adaptive principles are divided into two parts. First principle: the mobile terminal location update is based on the movement speed, and this information will pass to the system for dynamic management. The second principle: the required bandwidth of application is considered on selecting the most suitable wireless network dynamically. The application type consideration can also avoid handoff failures.
Through the experimental result, our proposed scheme is much more efficient than static scheme in most cases. In average cases, the signaling overheads are reduced up to 40%, and the paging delay are lower. Furthermore, the proposed scheme offers the better handoff trigger condition and timing to avoid handoff failures.

Chapter 1 Introduction 1
Chapter 2 Background and Related Work 5
2.1 WWAN/WLAN Interworking 5
2.2 Mobility Management 8
2.2.1 Location Management in Wireless Network 8
2.2.2 Handoff Management 14
2.3 Approach of UMTS 14
2.3.1 Packet Data Protocol Context 14
2.3.2 Packet Mobility Context States 16
Chapter 3 Speed Based Mobility Management 18
3.1 A Sample Scenario 18
3.2 Mobility Management 19
3.2.1 Users’ Movement Speed 20
3.2.2 Application Types 25
3.3 Communication Message Sequence 27
3.3.1 Interoperability between Location Management and Handoff Management 27
3.3.2 Paging Scheme Design 31
3.4 Performance Model 32
Chapter 4 Experiments 18
4.1 Experiment Set-up 36
4.1.1 Users’ Mobility Behavior 36
4.1.2 Experiment Environment 37
4.2 Experiment Parameters 39
4.3 Experiment Results 41
Chapter 5 Conclusion and Future Work 48

Reference 50

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