無線感測器網路經常被用來監控網路中的物體並且得知物體所在的位置。因為感測器有貯存的功能，所以一個無線感測器網路可以被當作為分散式系統的資料庫，讓感測器可以依據物體移動的行為不斷更新資料庫裡的資料以及提供使用者查詢網路中物體的位置資訊。之前相當多的研究人員已經研究出如何建造ㄧ個修剪訊息樹( Message Pruning Tree )，使得更新資料庫和查詢網路的物體的位置訊息有最小費用(最小費用修剪訊息樹的問題)。這個樹是以達到更新資料庫並且查詢物體位置的費用最小的目標下建造。在我們的論文裡，並不是建造一棵新修剪消息的樹，而是在一棵現有的樹上添加捷徑，並介紹一個新的資料聚集模型來降低整體費用的消耗。實驗模擬的結果顯示原本的樹加上我們提出來的方法會明顯的降低更新資料庫且查詢物體位置的費用。

Wireless sensor networks have often been used to monitor and report the locations of moving objects. Since sensors can also be used for storage, a wireless sensor network can be considered a distributed database, enabling us to update and query the location information of in-network moving objects. Many researchers have studied the problem of how to construct message-pruning trees that can update a database and query objects for the minimum cost (the Minimum Cost Message-Pruning Tree problem). The trees are constructed in such a way that the cost of updating the database and querying objects is kept as minimum as possible. In this thesis, instead of constructing a new message-pruning tree, we will add shortcuts to an existing tree, thus introducing a new data aggregation model. Simulation results show that the proposed method significantly reduces the cost of updating the database and querying objects.

[1] J. Aslam, Z. Butler, F. Constantin, V. Crespi, G. Cybenko, and D. Rus, “Tracking a moving object with a binary sensor network,” ACM SENSYS, pp. 150–161, 2003.
[2] F. Aurenhammer, “Voronoi diagrams – a survey of a fundamental geometric data structure,” ACM Computing Surveys, vol. 23, no. 3, pp. 345–405, 1991.
[3] K. Chakrabarty, S. S. Iyengar, H. Qi, and E. Cho, “Grid coverage for surveillance and target location in distributed sensor networks,” IEEE Transactions on Computers, vol. 51, no. 12, pp. 1448–1453, 2002.
[4] W. P. Chen, J. C. Hou, and L. Sha, “Dynamic clustering for acoustic target tracking in wireless sensor networks,” IEEE Transactions on Mobile Computing, vol. 3, no. 3, pp. 258–271, 2004.
[5] T. He, J. A. Stankovic, C. Lu, and T. F. Abdelzaher, “A spatiotemporal protocol for wireless sensor network,” IEEE Transactions on Parallel and Distributed Systems, vol. 16, no. 10, pp. 995–1006, 2005.
[6] B. Krishnamachari, D. Estrin, and S. Wicker, “Modelling data-centric routing in wireless sensor networks,” Technical Report CENG 02-14, 2002.
[7] S. Kumar, C. Alaettinoğlu, and D. Estrin, “Scalable object-tracking through unattended techniques (SCOUT),” IEEE ICNP, pp. 253–262, 2000.
[8] H. T. Kung and D. Vlah, “Efficient location tracking using sensor networks,” IEEE WCNC, pp. 1954–1961, 2003.
[9] C. Y. Lin, W. C. Peng, and Y. C. Tseng, “Efficient in-network moving object tracking in wireless sensor networks,” IEEE Transactions on Mobile Computing, vol. 5, no. 8, pp. 1044–1056, 2006.
[10] C. Y. Lin and Y. C. Tseng, “Structures for in-network moving object tracking in wireless sensor networks,” BROADNETS, pp. 718–727, 2004.
[11] K. Mechitov, S. Sundresh, Y. M. Kwon, and G. Agha, “Cooperative tracking with binary-detection sensor networks,” Technical Report UIUCDCS-R-2003-2379, 2003.
[12] T. Park and K. G. Shin, “Soft tamper-proofing via program integrity verification in wireless sensor networks,” IEEE Transactions on Mobile Computing, vol. 4, no. 3, pp. 297–309, 2005.
[13] H. Sabbineni and K. Chakrabarty, “Location-aided flooding: an energy-efficient data dissemination protocol for wireless sensor networks,” IEEE Transactions on Computers, vol. 54, no. 1, pp. 36–46, 2005.
[14] S. Slijepcevic and M. Potkonjak, “Power efficient organization of wireless sensor networks,” IEEE ICC, pp. 472–476, 2001.
[15] K. Sohrabi, J. Gao, V. Ailawadhi, and G. J. Pottie, “Protocols for self-organization of a wireless sensor network,” IEEE Personal Communications, vol. 7, no. 5, pp. 16–27, 2000.
[16] Y. Xu and W. C. Lee, “On localized prediction for power efficient object tracking in sensor networks,” ICDCSW, pp. 434–439, 2003.
[17] O. Younis and S. Fahmy, “HEED: a hybrid, energy-efficient, distributed clustering approach for ad hoc sensor networks,” IEEE Transactions on Mobile Computing, vol. 3, no. 4, pp. 366–379, 2004.
[18] W. Zhang and G. Cao, “DCTC: dynamic convoy tree-based collaboration for target tracking in sensor networks,” IEEE Transactions on Wireless Communications, vol. 3, no. 5, pp. 1689–1701, 2004.
[19] Y. Zou and K. Chakrabarty, “Sensor deployment and target localization in distributed sensor networks,” ACM Transactions on Embedded Computing Systems, vol. 3, no 1, pp. 61–91, 2004.