無線感測網路(Wireless Sensor Networks,WSNs) 是由多個視覺感測器及少數的無線資料收集器(Wireless Data Collector) 所組成。其主要功能是透過感測器收集所需資料，並將偵得結果以無線傳輸方式將資料回傳給無線資料收集器。
在過去的研究裡，已有許多研究使用視覺感測器建構防線(Barrier coverage)以獲得影像方面的資訊。而在影像資訊中，有考慮捕捉入侵物體寬度的研究，目前只有考量建構一條不論入侵者從什麼方向穿過防線，偵得入侵物體的最小寬度都必定高於門檻值的防線。但在這樣的研究裡，可能因為無法生成最小寬度高於門檻值的防線而直接宣告失敗。所以本論文希望在現有的防線上改善防線的最小寬度, 以最大化感測器偵得的物體寬度。我們提出一個區域式的改善方法，藉由每個視覺感測器自行改善與前後感測器的最小寬度來達到整條防線寬度提升的效果。
最後透過實驗模擬顯示，我們提出的演算法不會因為視覺感測器數量提升，而導致改善回合數增加，且不論防線初始的最小寬度為何，都能有效改善防線的最小寬度。
關鍵字: 無線感測網路，視覺感測器，防線，寬度。

Wireless sensor networks consists of multiple visual sensors and few wireless data collectors. The main function of wireless sensor networks is to return and collect information that sensors detect.
In order to consider information of image that sensors return, some studies has shown constructing barrier coverage by visual sensors to obtain information of image. However, they only consider constructing barrier by minimum sensors rather than the influence of width.Only a few study to consider width which needs to be higher than  width. In their studies, they may fail to construct barrier because it can’t generate barrier with at least  width. Therefore, in the algorithm, each sensor will improve its minimum width with previous and following sensors to increase the width of whole barrier line.
In summary, with the result of our simulation, the algorithm that we introduces will not decline by increasing sensor’s number. No matter what initial width is high or low, our algorithms improve the gap of barrier’s width in 0.6.

參考文獻
[1] C.-F. Cheng and K.-T. Tsai, “Distributed barrier coverage in wireless visual
sensor networks with -qom,” IEEE Sensors Journal, vol. 12, no. 6, pp. 1726–
1735, 2012.
[2] C.-F. Cheng and K.-T. Tsai, “Belt-barrier construction algorithm for WVSNs,”
in 2012 IEEE Wireless Communications and Networking Conference (WCNC),
pp. 3155–3160, IEEE, 2012.
[3] L. Guo, D. Kim, D. Li, W. Chen, and A. O. Tokuta, “Constructing beltbarrier
providing -quality of monitoring with minimum camera sensors,” in
2014 23rd International Conference on Computer Communication and Networks
(ICCCN), pp. 1–8, IEEE, 2014.
[4] D. Tao and T.-Y. Wu, “A survey on barrier coverage problem in directional
sensor networks,” IEEE Sensors Journal, vol. 15, no. 2, pp. 876–885, 2015.
[5] L. Zhang, J. Tang, and W. Zhang, “Strong barrier coverage with directional
sensors,” in Global Telecommunications Conference, 2009. GLOBECOM 2009.
IEEE, pp. 1–6, IEEE, 2009.
[6] J. Chen, B. Wang, W. Liu, L. T. Yang, and X. Deng, “Rotating directional sensors
to mend barrier gaps in a line-based deployed directional sensor network,”
IEEE Systems Journal, vol. 11, no. 2, pp. 1027–1038, 2014.
[7] Z. Wang, J. Liao, Q. Cao, H. Qi, and Z. Wang, “Barrier coverage in hybrid
directional sensor networks,” in 2013 IEEE 10th International Conference on
Mobile Ad-Hoc and Sensor Systems, pp. 222–230, IEEE, 2013.
[8] B. Xu, Y. Zhu, D. Li, D. Kim, and W. Wu, “Minimum (k, !)-angle barrier
coverage in wireless camera sensor networks,” International Journal of Sensor
Networks, vol. 19, no. 2, 2015.
[9] C.-Y. Chang, C.-Y. Hsiao, and C.-T. Chang, “The k-barrier coverage mechanism
in wireless visual sensor networks,” in 2012 IEEE Wireless Communications
and Networking Conference (WCNC), pp. 2318–2322, IEEE, 2012.
[10] Z. Wang, J. Liao, Q. Cao, H. Qi, and Z. Wang, “Achieving k-barrier coverage in
hybrid directional sensor networks,” IEEE Transactions on Mobile Computing,
vol. 13, no. 7, pp. 1443–1455, 2014.
[11] J. Du, K. Wang, H. Liu, and D. Guo, “Maximizing the Lifetime of-Discrete
Barrier Coverage Using Mobile Sensors,” IEEE Sensors Journal, vol. 13, no. 12,
pp. 4690–4701, 2013.
[12] S. F. A. Shah, S. Srirangarajan, and A. H. Tewfik, “Implementation of a directional
beacon-based position location algorithm in a signal processing framework,”
IEEE Transactions on Wireless Communications, vol. 9, no. 3, pp. 1044–
1053, 2010.
[13] K.-P. Shih, C.-M. Chou, I.-H. Liu, and C.-C. Li, “On barrier coverage in wireless
camera sensor networks,” in 24th IEEE International Conference on Advanced
Information Networking and Applications (AINA), pp. 873–879, IEEE, 2010.
[14] K.-F. Ssu, W.-T. Wang, F.-K. Wu, and T.-T. Wu, “K-barrier coverage with a
directional sensing model,” International Journal on Smart Sensing and Intelligent
Systems, vol. 2, no. 1, pp. 75–93, 2009.