無線感測器網路(Wireless Sensor Network, WSN)，廣泛的被應用在軍事、工業、水與空氣等資源的環境監控等等各個領域，但由於每個感測器的電力來源非常有限，故網路壽命向來是一項議題。針對此一議題，可移動式的中繼節點(Mobile Relay Nodes)與由其組成的結構被應用且廣泛的探討著。經由這些中繼節點提供的可移動性，讓節點能夠依照狀況移動到適當的位置，進而能延長無線感測器網路的壽命。基於這樣的技術，本篇論文提出了一個可調整的結構：LaCRE (Lifetime-aware Configuration with Residual Energy)，使得感測器網路的壽命能夠大幅的延長。 LaCRE與其他方法最大不同點在於，LaCRE以網路壽命作直接考量，而其他方法多以將資料傳輸之電量消耗最小化為目標。LaCRE設計一個以電量消耗與節點壽命為參數的方程式，計算出每個傳輸階段可移動節點的最適位置，讓整體感測器網路的壽命能夠再次的延長。在我們的模擬結果顯示，在相同拓撲的結構下，網路資料傳輸的電量消耗方面，LaCRE比起不可移動式節點感測器網路，約節省了10% 至15% 的電量；並且在我們主要考量的感測器網路壽命，LaCRE也較相同拓撲的不可移動式節點感測器網路提升了10% 至40%。

Lifetime is always a critical issue in sensor networks due to limited battery capacity, especially in data-intensive applications, such as military monitoring, environment or earth sensing, and audio/video surveillance. To address the issue, deployments of relay nodes and configuration of mobile relays are widely studied in the sensor networks. Because mobile relays provide an ability of movement, the lifetime of sensor networks can be adaptively extended according to the current state of sensor networks. Based on the benefit of using mobile relay, this paper proposes an adaptive relay configuration called LaCRE (Lifetime-aware Configuration with Residual Energy), which tries extremely to prolong the lifetime of sensor networks. The most different between LaCRE and other approaches is that LaCRE focuses on prolong the lifetime of sensor networks while other approaches try to minimize the power consumption of data transmissions. The LaCRE designs an equation that combines the lifetime-aware and the energy-aware parameters to calculate a new location for mobile relay movement. At the new location, the mobile relay can better prolongs the lifetime of the sensor networks. Our simulation results show that the LaCRE can reduce the power consumption of data transmissions in the sensor network by 5-8% compared to the relays without movements. Moreover, compared to other solutions, LaCRE increase the lifetime of the sensor networks up to 2 times.

摘要 1
Abstract 2
1 引言 5
1.1. 無線感測器網路 5
1.2. 文章架構 6
2 研究背景 7
2.1 相關研究 7
2.2 研究動機 9
2.3 耗能模型 9
2.4 範例探討 11
2.5 問題定義 12
3 感測器之壽命導向結構 13
3.1 基礎想法 13
3.2 兩階段的感測器壽命延長策略 14
4 感測器網路之壽命導向樹狀結構 17
4.1 網路壽命之權重定義 17
4.2 樹狀結構路由 18
5 感測器網路之最適結構 20
5.1 可移動式感測器的壽命議題 20
5.2 壽命最適化演算法 20
6 實驗設置與模擬結果 22
6.1 實驗一 22
6.2 實驗二 25
6.3 實驗三 27
7 結論 29
8 參考文獻 30

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