廖婉君臺灣大學：電機工程學研究所吳岳庭Wu, Yueh-TingYueh-TingWu2007-11-262018-07-062007-11-262018-07-062006http://ntur.lib.ntu.edu.tw//handle/246246/53360在移動無線隨意網路中，移動性是一個重要的議題，由於網路中節點移動性的存在，路由協定的效能也會受到影響。隨著各種描述節點運動情況的模型被提出之後，對於移動性不論是數學分析或是實作方面都有許多更深入的研究。 在過去的文獻中我們知道在網路中節點間連線維持時間是衡量移動性一個重要的標準。我們從分析中發現，連線維持時間是由在連線維持過程中節點在另一節點傳輸範圍中移動的速度以及移動的距離所決定，這兩個數值又分別由兩節點速度的夾角以及形成連線時一個節點進入另一個節點傳輸範圍時的角度決定，以這兩個角度的機率分布為起點我們推導出連線維持時間的機率分布，並且在不同的現存移動模型中以模擬驗證我們的分析正確性，模擬結果顯示不論在點對點或是點對多點的情況下我們的分析都有很高的正確性。另外我們也提出了兩個連線維持時間機率分布可以實際應用的例子。Mobility is an important feature of mobile ad hoc networks (MANET). People are concerned about the impact of mobility on the performance of routing protocols in MANET. Therefore many mobility models are proposed for further analysis or simulations based research. In the previous literatures, we found that link duration is an important metric measuring the extent of mobility, where the link duration is referred to as the time interval in which two nodes stay within transmission range of each other. We find that link duration is determined by the relative speed and active distance between two nodes, which are in turn determined by the angles of the two nodes’ velocities and the incident angle of one node to the other node’s transmission range. We derive the probability distribution function of link duration for two nodes in multi-hop mobile networks and validate the analytical result via simulations. The analytical result is extended to model multipoint links which appear in existing group mobility models. The accuracy of our framework is validated by simulations based on existing mobility models, and the usability of our model is also demonstrated. The results show our model can well describe the link duration distribution for both types of links in multi-hop mobile networks, especially when the transmission range of each node is relatively smaller than the entire network coverage. At the end of this thesis, we also provided two possible applications based on our model.Table of Contents Chapter 1 Introduction__________________________________1 1.1 Related Work____________________________________2 1.2 Mobility Models_________________________________4 1.2.1 Random Walk Mobility Model______________________5 1.2.2 Random Waypoint Mobility Model__________________6 1.2.3 Freeway, Manhattan Mobility Model_______________7 1.2.4 Reference Point Group Mobility Model____________8 1.3 Motivation______________________________________9 1.4 Organization____________________________________10 Chapter 2 Analytical Model of Link Duration_____________11 2.1 Assumptions and Notations_______________________12 2.2 Link Duration between Two Nodes_________________14 2.3 The Probability Distribution of Link Duration for Point-To-Point Links without Pause__________17 2.4 Link Duration with Pause________________________24 2.5 Link Duration of Multi-Point Links______________26 Chapter 3 Performance Evaluation________________________29 3.1 Point-to-Point Links____________________________30 3.1.1 Nodes with Fixed Speed__________________________31 3.1.2 Nodes with Different Speeds_____________________33 3.2 Link Duration with Pause________________________35 3.3 Boundary Effect of Link Duration________________36 3.4 Multi-Point Links_______________________________38 Chapter 4 Applications__________________________________40 4.1 Relationship between Link Duration and Routing Overhead________________________________40 4.2 Help on Designing Routing Protocol______________43 Chapter 5 Conclusion and Future Work____________________46 Reference________________________________________________47 List of figures Figure 1-1. Example of node movement in random walk mobility model________________________________5 Figure 1-2. Example of node movement in random waypoint mobility model________________________________6 Figure 1-3. Maps of Freeway and Manhattan mobility model_________________________________________7 Figure 1-4. Example of node movement in Reference Point Group Mobility________________________________8 Figure 2-1. Relationship between two nodes_______________14 Figure 2-2. An illustration of calculating Pr{}__________17 Figure 2-3. Relationship between member node and leader node_________________________________________27 Figure 3-1. The distribution of T with fixed moving speed Vfix=10,r=150________________________________32 Figure 3-2. The active distance at different entering point________________________________________32 Figure 3-3. Figure 3-3. The pdf of T with uniformly distributed speeds___________________________33 Figure 3-4. The pdf of T with non-uniformly distributed speeds_______________________________________34 Figure 3-5. The distribution of T with pause time 50s r=150________________________________________35 Figure 3-6. The distribution of T with fixed moving speed Vfix=10,r=150________________________________36 Figure 3-7. The distribution of T with fixed moving speed Vfix=10,r=200________________________________37 Figure 3-8. The distribution of T with fixed moving speed Vfix=10,r=250________________________________37 Figure 3-9. The pdf of multi-point link duration_________38 Figure 4-1. Average link duration at different speed_____40 Figure 4-2. Overhead versus 1/link duration______________41 Figure 4-3. Mobility Detection Algorithm_________________43 Figure 4-4. The cdf of link duration_____________________44 List of tables Table 2-1. Notations used in analysis____________________13 Table 3-1. The parameters in simulation for point-to-point link with fixed speed_________________________32 Table 3-2. The parameters in simulation for point-to-point link with uniformly distributed speed_________33 Table 4-1. Simulation settings using AODV________________40586929 bytesapplication/pdfen-USwireless mobile ad hoc networklink duration移動無線隨意網路連線維持時間thesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/53360/1/ntu-95-R93921025-1.pdf