隨著無線通訊的進步，以往的軍事戰場上皆利用派駐軍隊來保護自己的疆土。如今，即可利用感測器的感測能力來進行入侵者偵測，減少防守時所需消耗的人力資源。本篇論文探討在無線感測網路中，如何使網路被認為是很重要的區域不成為受到Sensor Nodes感測能力最薄弱路徑的一部分，進而達到防禦的目的。本論文提出一個藉由Sensor Nodes的移動來改變網路上入侵者入侵的路徑，使之不入侵網路上的Vulnerable Area，因為Vulnerable Area視為一很重要的區域。為了避免消耗過多Sensor Nodes的電量，本篇論文所提出的演算法只需移動少數的Sensor Nodes，即可改變網路上受到Sensor Nodes感測能力最薄弱的路徑，並且解決了Sensor Nodes移動後仍再進入Vulnerable Area的問題，由於每個Sensor Nodes的剩餘電量不一，因此亦考慮了所移動的Sensor Nodes是否有足夠的電量進行移動，以完成改變入侵者入侵的路徑。實驗結果顯示出，本論文所提出的方法可以使Sensor Nodes以較少的移動消耗電量與移動的Sensor Nodes個數，使得網路中受到Sensor Nodes感測能力最薄弱的路徑不再經過Vulnerable Area，且達到節省電量的效果。

This thesis discusses on how to let the vulnerable area in the network will not be affected by the sensor node's sensing ability as the weakest path of the network in wireless sensor networks. This paper addresses by moving sensor nodes to change the vulnerable path in the network so that it does not cross the vulnerable area in the network, hence it achieves the purpose of defense. In order to avoid excessive consumption of electricity to the sensor nodes, the algorithms which this paper proposed only deals with moving a small number of paths to the sensor nodes, then by using the sensor node's sensing ability it then can detect the weakest path. The simulation results shows that the proposed VAPM algorithm can reduce the total energy consumption for changing the vulnerable path, and the energy consumption will not affected by network density and the radius of the vulnerable area.

目    錄
目    錄.................................................I
圖 目 錄...............................................III
第一章、緒論.............................................1
1.1 研究背景.............................................1
1.2 研究動機.............................................3
1.3 研究目的.............................................4
1.4 論文架構.............................................5
第二章、背景知識與相關研究...............................6
2.1 背景知識.............................................6
2.2 相關研究.............................................8
第三章、網路環境與問題敘述..............................12
3.1 網路環境............................................12
3.2 問題敘述............................................14
第四章、Vulnerable Area Protection Movement Protocol....16
4.1 Critical Vertexes Searching.........................17
4.2 Critical Vertexes Moving............................21
4.2.1 改變Weight數值....................................21
4.2.2 改變路徑斜率......................................26
4.2.3 路徑消除..........................................28
4.3 Critical Sets Selection	.............................29
4.4 Optimal Critical Set................................31
第五章、實驗............................................33
5.1 實驗環境及參數......................................33
5.2 比較方法............................................33
5.3 實驗結果............................................34
第六章、結論............................................37
參考文獻................................................38
附錄─英文論文..........................................41


圖 目 錄
圖一：場景圖.............................................4
圖二：Voronoi Diagram....................................7
圖三：給予Voronoi Diagram權重值..........................8
圖四：Maximal Breach Path[10][11]........................9
圖五：入侵者入侵路徑選擇................................13
圖六：Critical Vertexes Searching.......................19
圖七：改變Voronoi Edge的Weight數值(1)...................21
圖八：改變Voronoi Edge的Weight數值(2)...................22
圖九：同時改變兩相鄰Voronoi Edge的Weight數值............23
圖十：改變Voronoi Edge的Weight數值(需移動的方向和距離)..24
圖十一：改變Voronoi Edge斜率............................27
圖十二：改變Voronoi Edge c 斜率.........................27
圖十三：消除Voronoi Edge................................29
圖十四：改變入侵者入侵路徑..............................34
圖十五：網路點數與耗電量關係............................35
圖十六：Vulnerable Area大小與耗電量關係.................36

[1] Q. Zhao and M. Gurusamy, “Maximizing Network Lifetime for Connected Target Coverage in Wireless Sensor Networks,” in Proceedings of the IEEE International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob 2006), pp. 94-101, Jun. 2006.
[2] I. Cardei, M. T. Thai, Y. Li, and W. Wu, “Energy-Efficient Target Coverage in Wireless Sensor Networks,” in Proceedings of the IEEE INFOCOM, the 24th Annual Joint Conference of the IEEE Computer and Communication Society, vol. 3, pp. 1976-1984, Mar. 2005.
[3] S. Yang, F. Dai, M. Cardei, and J. Wu, “On Multiple Point Coverage in Wireless Sensor Networks,” in Proceedings of the International Conference on Mobile Ad-hoc and Sensor Systems (MASS 2005), pp. 757-764, Nov. 2005.
[4] S. Kumar, T. H. Lai, and A. Arora, “Barrier Coverage with Wireless Sensors,” in Proceedings of the 11th Annual International Conference on Mobile Computing and Networking (MobiCom 2005), pp. 284-298, Aug. 2005.
[5] Q. Cao, T. Abdelzaher, T. He, and J. Stankovic, “Towards Optimal Sleep Scheduling in Sensor Networks for Rare-Event Detection,” in Proceedings of the IEEE International Symposium on Information Processing in Sensor Networks (IPSN 2005), pp. 20-27, Apr. 2005.
[6] D. Tian and N. D. Georganas, “A Coverage-Preserving Node Scheduling Scheme for Large Wireless Sensor Networks,” in Proceedings of the ACM 1st International Workshop on Wireless Sensor Networks and Applications (WSNA 2002), pp. 32-41.
[7] J. Jiang, and W. Dou, “A Coverage-Preserving Node Scheduling Algorithm for Self-organized Wireless Sensor Networks,” in Proceedings of the Grid and Cooperative Computing Workshops (GCC 2004), pp. 587-596.
[8] C.-F. Huang and Y.-C. Tseng, “The Coverage Problem in a Wireless Sensor Networks,” in Proceedings of the International Conference on Wireless Sensor Networks and Applications (WSNA 2003), pp. 115-121.
[9] Y.-T. Hou, T.-C. Lee, C.-M. Chen, B.-C. Jeng, “Node Placement for Optimal Coverage in Sensor Networks,” in Proceedings of the IEEE International Conference on Sensor Networks, Ubiquitous, and Trustworthy Computing, vol.1, pp. 352-357, June 2006.
[10] S. Megerian, F. Koushanfar, M. Potkonjak, and M. B. Srivastava, “Worst and Best-case Coverage in Sensor Networks,” IEEE Transactions on Mobile Computing, vol. 4, no. 1, pp. 84-92, Jan. 2005.
[11] S. Megerian, F. Koushanfar, M. Potkonjak, and M. B. Srivastava, “Coverage Problems in Wireless Ad-hoc Sensor Networks,” in Proceedings of the IEEE INFOCOM, the 20th Annual Joint Conference of the IEEE Computer and Communication Society, vol. 3, 2005, pp. 1380-1387.
[12] X.-Y. Li, P.-J. Wan, and O. Frieder, “Coverage in wireless ad hoc sensor networks,” IEEE Transactions on Computers, vol.52, no.6, pp. 753-763, June 2003.
[13] R.-H. Gau, and Y.-Y. Peng, T. LaPorta, “A Dual Approach for The Worst-Case-Coverage Deployment Problem in Ad-Hoc Wireless Sensor Networks,” in Proceedings of the International Conference on Mobile Ad-hoc and Sensor Systems (MASS 2006), pp. 427-436 , Oct. 2006.
[14] S. Zhou, M.-Y. Wu and W. Shu, “Blocking Vulnerable Paths of Wireless Sensor Networks” in Proceedings of the IEEE Global Telecommunications Conference (GLOBECOM 2006), pp. 1-5, Nov. 2006.
[15] N. Ahmed, S. S. Kanhere, and S. Jha, “The Hole Problem in Wireless Sensor Networks : A Survey,” in Proceedings of the ACM SIGMOBILE Mobile Computing and Communications Review, vol 9, pp. 32-41, 2005.
[16] S. Megerian, F. Koushanfar, G. Qu, and M. Potkonjak, “Exposure in Wireless Ad-Hoc Sensor Networks,” in Proceedings of the 7th Annual International Conference on Mobile Computing and Networking (MobiCom 2001), pp. 139-150.
[17] G. Wang, G. Cao, and T. LaPorta, “A Bidding Protocol for Deploying Mobile Sensors,” in Proceedings of the IEEE International Conference on Network Protocols (ICNP 2003), pp. 315-324, Nov. 2003.
[18] G. Wang, G. Cao, and T. LaPorta, “Movement-Assisted Sensor Deployment,” in Proceedings of the IEEE INFOCOM, the 23th Annual Joint Conference of the IEEE Computer and Communication Society, vol. 4, pp. 2469-2479, Mar. 2004.
[19] G. Wang, G. Cao, and T. LaPorta, “Proxy-Based Sensor Deployment for Mobile Sensor Networks,” in Proceedings of the International Conference on Mobile Ad-hoc and Sensor Systems (MASS 2004), pp. 493-502 , Oct. 2004.
[20] K.-P. Shih, H.-C. Chen, J.-K. Tsai, and C.-C. Li, “PALMA Partition Avoidance Lazy Movement Protocol for Mobile Sensor Networks,” in Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC 2007), pp. 2484-2489 , Mar. 2007.