無線感測網路(Wireless Sensor Network)的存活期取決於感測器的電池電量，由於感測器通常以隨機方式佈建於網路中，且其運作一段時間後剩餘電量可能不一致，若利用傳統的Voronoi Diagram來劃分每個感測器的感測區，則電量小的感測器會為了與鄰居平均分攤感測範圍而很快地耗損其所有的電量。本論文所考慮的感測器其感測範圍為可調式，電量之消耗與感測半徑成平方比例，在這樣的環境下，根據各個感測器的電量不同，發展一具有電量平衡的Weighted Voronoi Diagram，並據此劃分感測器應有的有效感測區域，使電量較大的感測器可以擁有較大的感測半徑，藉以達到電量平衡及全區覆蓋的目的。除了討論1-Coverage的技術外，本論文亦擬將可調感測範圍的技術延伸達到k-Coverage的覆蓋目標。模擬結果顯示，本演算法在1-Coverage之網路存活期的效能上，有明顯的改善，延伸在k-Coverage的技術也有極佳的效能。

Coverage is one of the most important issues in wireless sensor networks (WSNs). Given a randomly deployed WSN, how to achieve the both purposes of maintaining full coverage and maximizing network lifetime has been received much attention in recent years. This paper considers the area coverage problem for a WSN where each sensor has variable sensing radius. A Weighted Voronoi Diagram (WVD) is proposed as a tool for determining the sensing region of each sensor node according the remaining energy in a distributed manner. To maximize the network lifetime, techniques for balancing energy consumption of sensors are further proposed. Simulation results reveal that the proposed energy-balanced coverage mechanism outperforms the existing works in terms of network lifetime.

圖目錄	V
表目錄	VII
第一章、簡介	1
第二章、網路環境與問題描述	5
2.1 網路環境	5
2.2 問題描述	7
第三章、Adjustable Sensing Range (ASR) Mechanism	9
3.1 Phase I: WVD Construction Phase	9
3.2 Phase II: Overlapping Reduction Phase	18
3.3 Phase III: Improvement on Network Lifetime	24
第四章、k-Coverage 設計	30
4.1 消失法	30
第五章、模擬分析	34
第六章、結論	42
參考文獻	43
附錄-英文論文	46

圖目錄
圖(1). 剩餘電量之重心產生電量消耗不公平的情況發生。	3
圖(2). 具權重式的Voronoi Diagram來劃分各感測器應負責的感測區域。	11
圖(3). 特殊三角形區域SA區域形成。	12
圖(4). 藉由Division Point的存在解決T-Hole Problem。	13
圖(5). 各感測器在T-Hole中所負責的區域。	15
圖(6). 解決T-Area problem後，感測器會各自擁有自己的監控區域。	16
圖(7). WVD Construction Phase。	17
圖(8). sj的RCj被Fixed Sensor si所覆蓋後剩餘面積。	19
圖(9). 感測器sa和sb為Fixed Sensor。	20
圖(10). 感測器sa或sb其中一方縮減其感測範圍，會導致空洞問題產生。	22
圖(11). 由於有FS之存在，AS可進一步地縮減其感測半徑，以節省電量消耗。	23
圖(12). Overlapping Reduction Phase。	24
圖(13). 延長存活期最短之感測器的生命週期。	26
圖(14). 縮小感測半徑可以延長存活期，但會造成空洞產生。	27
圖(15). sh之幫助，可以輕易的治療空洞。	28
圖(16). Improvement on Network Lifetime Phase。	29
圖(17). 感測器sa與sb劃分感測器sd的監控區域。	31
圖(18). 感測器執行消失法後即可達到2-Coverage之目標。	32
圖(19). k-Coverage。	33
圖(20). 感測器之個數對網路存活期之影響。	35
圖(21). 感測器之個數對平均感測半徑之影響。	36
圖(22). 感測器之個數對重疊區域之影響。	37
圖(23). Sink位於網路場景角落。	37
圖(24). Sink位於網路場景中心。	38
圖(25). 各階段之重疊率比較圖。	39
圖(26). 各階段之網路存活期比較圖。	39
圖(27). 覆蓋率比較圖。	40

表目錄
表(1). 環境參數	34

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