在可充電無線感測網路(Wireless Rechargeable Sensor Networks)中，如何讓具有行動能力的感測器能夠在耗盡電量前回到充電站充電是一項非常重要的研究議題。在本研究中，我們提出一個透過連座式(Cascaded Movement)的移動方式來平衡可充電感測網路中行動感測器的電量消耗。在事件導向的無線感測網路中，場景中感測器的耗電量會因為事件發生的次數不同而有所不同。我們可以調度位於剩餘電量較低感測器周圍的感測器來進行協助，然後讓剩餘電量較低的感測器向充電站慢慢靠近，等到有閒暇的感測器能來替補位置時，就可以花費較少電量回到充電站為其充電。利用這種方法可以有效平衡網路的電量，讓電量較低的靠近充電站，電量充足的在離較遠的地區感測，這種方法可以有效延長整個網路的存活時間。我們經過模擬的實驗結果證明這兩種機制能有效的提升無線感測器網路的網路存活時間。

The energy replenishment problem is an important issue in wireless rechargeable sensor networks (WRSNs). In this study, we address the energy replenishment problem with mobile sensor in WRSNs. To achieve energy balancing between mobile sensors, we propose an energy balancing algorithm based on cascaded movement. The proposed energy balancing algorithm can find a better cascading schedule for the cascaded movement. To replace mobile sensors with a low remaining energy level, we propose a redundant mobile sensors dispatch algorithm. The proposed redundant mobile sensors dispatch algorithm will dispatch fully charged redundant mobile sensors to mobile sensors whose energy should be replenished as soon as possible. This ensures that mobile sensors most in need of a recharge can return to the charging station first.

目錄
圖目錄 IV
表目錄 V
第一章　簡介 1
第二章　問題定義以及環境假設 6
第三章　方法概述	9
3.1 冗餘移動感測器調度機制 9
3.2 能量平衡機制	10
第四章　實驗模擬	14
4.1 實驗一：感測器數量的變化對於網路存活時間的影響 15
4.2 實驗二：場景大小的變化對於網路存活時間的影響 16
4.3 實驗三：MS值的變化對於網路存活時間的影響 17
4.4 實驗四：tholdhigh值的變化對於網路存活時間的影響 18
第五章　結論 19
參考文獻	20
附錄-英文論文 22

圖目錄
圖 1. 連座式排程 4
圖 2. WRSN示意圖	6
圖 3. Cascaded movement成員的挑選範圍 12
圖 4. Cascading schedule範例 12
圖 5. 感測器數量對網路存活時間的影響 15
圖 6. 感測器數量對SD值的影響 15
圖 7. 場景大小對網路存活時間的影響	16
圖 8. 場景大小對SD值的影響 17
圖 9. 不同MS值對網路存活時間及SD值的影響 17
圖 10. tholdhigh對網路存活時間及SD值的影響 18


表目錄
表 1. 符號 8
表 2. 模擬參數 14

參考文獻
[1]	U. Baroudi, “Robot-assisted maintenance of wireless sensor networks using wireless energy transfer,” IEEE Sensors J., vol. 17, no. 14, pp. 4661-4671, 2017.
[2]	S. Bi, Y. Zeng, R. Zhang, “Wireless powered communication networks: an overview,” IEEE Wirel. Commun., vol. 23, no. 2, pp. 10-18, 2016.
[3]	Y. Feng, N. Liu, F. Wang, Q. Aian, X. Li, “Starvation avoidance mobile energy replenishment for wireless rechargeable sensor networks,” in Proc. IEEE ICC, 2016, pp. 1-6.
[4]	S. Guo, C. Wang, Y. Yang, “Mobile data gathering with wireless energy replenishment in rechargeable sensor networks,” in Proc. IEEE INFOCOM, 2013, pp. 1932-1940.
[5]	L. He, P. Cheng, Y. Gu, J. Pan, T. Zhu, C. Liu, “Mobile-to-mobile energy replenishment in mission-critical robotic sensor networks,” in Proc. IEEE INFOCOM, 2014, pp. 1195-1203.
[6]	L. He, L. Kong, Y. Gu, J. Pan, T. Zhu, “Evaluating the on-demand mobile charging in wireless sensor networks,” IEEE Trans. Mobile Comput., vol. 14, no. 9, pp. 1861-1875, 2015.
[7]	W.R. Heinzelman, A. Chandrakasan, H. Balakrishnan, “An application-specific protocol architecture for wireless microsensor networks,” IEEE Trans. Wireless Comm., vol. 1, no. 4, pp. 660-670, 2002.
[8]	H. Hu, S.V. Georgakopoulos, “Multiband and broadband wireless power transfer systems using the conformal strongly coupled magnetic resonance method,” IEEE Trans. Ind. Electron., vol. 64, no. 5, pp. 3595-3607, 2017.
[9]	K. Huang, C. Zhong, G. Zhu, “Some new research trends in wirelessly powered communications,” IEEE Wirel. Commun., vol. 23, no. 2, pp. 19-27, 2016.
[10]	S. Ishino, I. Takano, K. Yano, N. Shinohara, “Frequency-division techniques for microwave power transfer and wireless communication system with closed waveguide,” in Proc. IEEE WPTC, 2016, pp. 1-4.
[11]	G.M. Karageorgos, C. Manopoulos, A. Kiourti, A. Karagiannis, S. Tsangaris, K. Nikita, “An approach for self-powered cardiovascular monitoring based on electromagnetic induction,” IEEE Sensors J., DOI: 10.1109/JSEN.2017.2699123, 2017. 
[12]	Q. Liu, J. Wu, P. Xia, S. Zhao, W. Chen, Y. Yang, L. Hanzo, “Charging unplugged: will distributed laser charging for mobile wireless power transfer work?,” IEEE Veh. Technol. Mag., vol. 11, no. 4, pp. 36-45, 2016.
[13]	N.T. Nguyen, B.H. Liu, V.T. Pham, C.Y. Huang, “Network under limited mobile devices: a new technique for mobile charging scheduling with multiple sinks,” IEEE Syst. J., DOI: 10.1109/JSYST.2016.2628043, 2017.