我們在無線感測網路中，提出一種新的具調適性的省電媒體存取控制協定，稱為EX-MAC。在現存的一些以省電為目的的媒體存取控制協定，如S-MAC，會讓感測節點周期性的進入睡眠模式以節省能源。然而在這些協定中，每個節點的工作周期(Duty cycle)在加入網路之前便決定了，在運作的時候也是維持固定不變。因此，當處於高流量的情況時，網路的效能會降低；在低流量時，不必要的能源消耗會加劇。在我們提出的EX-MAC協定中，每個感測節點會動態的調整自己的工作周期，使得節點的工作周期能符合網路的真實需求。EX-MAC調整工作周期的技術，是基於極值理論(Extreme value theory)來動態且準確的估計最適合的工作周期。因此，EX-MAC能夠適應網路流量、網路規模以及拓墣的變化。最後，我們的模擬結果顯示，相較於S-MAC，EX-MAC不僅消耗更少的能源，還具有更好的效能表現。

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