在無線感測器網路(Wireless Sensor Network)中，無線網路的壽命倚賴於感測器的電池電量，所以能量保存是一個很重要的課題。因此我們期望設計出一個適合於無線感測器網路環境，並且能有效節省耗電量的新協定。我們觀察到感測器通常是以不規則的方式放置，因此有可能會使拓撲出現一些間隔，若這些在間隔邊的點要傳送資料時均以較大的能量傳送，便會很快消耗掉能量。本篇論文提出一個嶄新的分散式省電協定，此方法可以降低總體的耗電量，並延長網路的存活時間。此協定是藉由兩種不同的廣播來達到以最適當的傳輸功率傳輸資料的目的，相近的感測器會以multi-hop的方式用最小的傳輸功率連通，而形成一群集，並由其中一個用較大的傳輸功率把資料送至其他群集，藉以達到省電的目的。本協定必考慮到若一直由同一感測器利用大功率傳輸會很快耗盡能量的情況，因此也提供了一個簡單的方法來選取後備點。模擬的結果指出這個協定可以有效的降低整體的耗電量，並延長網路的存活時間。 Power consumption is the main factor of the wireless communication. The lifetime of the wireless sensor network depends on the durability of battery resource of the sensor nodes. In our protocol we want to reduce the transmission power among the sensor nodes to save energy and maintain a connected network topology. In this thesis, we present a distributed algorithm to construct a tree topology of sensor nodes. The sensor nodes will use the suitable transmission power level to connect to the parent nodes. This algorithm works in a multihop wireless network without any knowledge of the local positions. It can adjust the transmission power and maintain a connected topology. We also provide a simple way to change the power level after the topology construction is finished. Our experimental results show that our protocol, even if being a distributed one, is the best of its kind to extend the lifetime of the sensor network and to conserve the energy of the nodes up to optimum level and better than the centralized algorithms.
