臺灣博碩士論文加值系統

隨著新一代無線網路-802.16 WiMAX的出現，越來越多的應用將在WiMAX上面實現。相較於WiFi，WiMAX具有更大的頻寬與傳輸距離，所以有許多廠商認為WiMAX將會取代3G系統成為新一代的手機協定。此外，WiMAX 可應用領域相當廣泛，包含私人企業、回程線路、寬頻無線網路服務、攜帶式寬頻無線。
本研究是為WiMAX型態的網路所量身訂作的群播技術。雖然群播的相關研究已經很多，不論是傳統實體網路或是無線網路都有相當多的路由方法提出。但是WiFi下的群播型態為存取點到使用者與WiMAX下的BS到SS到存取點，兩者所用方法不盡相同。事實上，到目前為止尚未有合適WiMAX三層架構的群播路由方式提出。這個情形導致在單一傳送的網路下，只要有兩個以上接收端要求同樣的資料流，就會造成發送端發送多份相同資料到接收端的狀況，造成網路資源的浪費。
舉例來說，當有多個使用者在進行多方會談的視訊會議，雖然是分開的使用者，但是卻接收到來自相同的聲音與視訊資料，在沒有使用群播的狀況下，將會重複多個資料的傳送。相反的，使用群播的方式，將會大大減低重複的資料重複傳輸率。
有鑑於此，本研究針對具有在全球互通的微波存取網路，設計出符合WiMAX之多層架構的群播方式。本研究的方法是在BS與SS上面設計一套能夠認得群播封包的機制，當BS與SS收到此種封包，BS就不會重複的發送資料到SS，而是發送一個包有參與這次群播的接收端的封包到SS。當SS接收到後，再將此資料分送到屬於此群組的接收端。
在WiMAX網路下建立出本研究的群播協定，能夠有效地將資料持續傳送到群播群組的接收端中。由實驗結果顯示，若與沒有實行群播協定之網路作比較時，本研究提出的WiMAX群播應用協定在接收端到達一定數量時，網路負載與平均延遲將會大大降低，網路佔用率得以下降，並提高網路頻寬，成功增加網路效能。

As a new wireless network-802.16 (WiMAX) appeared, more and more applications will be use on WiMAX network. Compare with WiFi, WiMAX equips bigger bandwidth and distance of transmission. There were many companies thought that WiMAX will replace 3G system to a new protocol of cellular phone. Besides, applications of WiMAX are very popular; including private business, service of broadband wireless, and mobile broadband.

This study proposed a multicast mechanism based on WiMAX attributes. Although there are a lot of researches proposed multicast protocol [1-3], in traditional or wireless network. But the way of multicast assess in WiFi are different from WiMAX’s BS to SS. There has no a fixed WiMAX multicast mechanism till today. This situation leads to bandwidth’s waste when two receivers request the same data from a single source. For example, when many users were join a video meeting. Even though there are separate users, but they are receiving the same video and audio data, without using multicast mechanism, the source will transmit many duplicated data to users. It would be reducing the network load when multicast scheme enable.

This study focuses on Worldwide Interoperability for Microwave Access, and designs a suitable mechanism for WiMAX multicast. The proposed mechanism is to design a scheme which BS and SS can recognize multicast packet. When BS and SS receive this kind of packet, BS will not send duplicated packet to SSs, and send a packet which contains who joins this multicast group to SS. When SS gets the multicast packet, it will automatically forward to the receiver which belongs to this multicast group.

The proposed WiMAX network multicast application mechanism can handle the data sending to the receivers successfully, and continually delivery the data to group members. The simulation results indicate that proposed multicast mechanism can reduce the network load and average delay time when the receivers become more and more. This mechanism reduces the link Utilization, increases network bandwidth, and increases the performance of network.

摘要 I
Abstract III
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Organization of This Thesis 4
Chapter 2 Background Knowledge and Related Work 5
2.1 802.16 (WiMAX) Network Architecture 5
2.2 Anycast, Unicast, Broadcast and Multicast 10
2.3 Multicast Application 11
2.4 Quality of Service Support in WiMAX Network 14
2.5 Reliable Multicast Classification 17
2.6 Multicast Scheme for Wireless Mobile Network 20
Chapter 3 Proposed WiMAX Multicast Mechanism 23
3.1 Core Base Tree Data Forwarding 23
3.2 Group Management 24
3.3 Error Recovery 25
3.4 Fast-Handoff Scheme 29
3.4.1 Hierarchical Structure 29
3.4.2 Handoff Approach 30
3.4.3 Mobile Client as Source 32
3.4.4 Mobile Host as Receiver 34
Chapter 4 Simulation Analysis and Discussion 37
4.1 Simulation Environment 37
4.2 Simulation Metrics 39
4.3 Network Load 40
4.4 Link Occupation 43
Chapter 5 Conclusion and Future Work 45
5.1 Conclusion 45
5.2 Future Work 45
References 47

References

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