無線感測網路是近幾年備受矚目的研究領域，在國內外的研究中，已經有許
多相關的應用問世，這些應用大多需要長時間運作，但無線感測網路中每一個節點所搭載的電量都是有限的，當部分感測器的電量耗盡時，相關應用可能無法繼續維持，因此在無線感測網路環境下節省能源消耗是一個很重要的議題。在低工作週期的無線感測網路下可以有效解決耗能的問題。但是在這種網路環境下，匯點傳資料到每一個感測器的延遲會變得相當大，因為每一個感測器大部分時間都是休眠狀態只有少部分的時間為活動狀態。所以網路中找尋匯點擺放位置變得非常重要，到目前為止這是在低工作週期的無線感測網路中一個新的問題。在本篇文章中提出了一個基於將感測器分群方法找尋匯點在網路中之位置。提出的演算法分成三個步驟，1)建立群集2)建構群集中的表格3)找出匯點最佳位置。最後模擬結果顯示，本論文提出的方法和最佳解演算法找出來的位置之平均延遲時間非常接近，但此演算法運算時間比最佳解演算法還要快。

In the wireless sensor networks (WSNs), energy consumption is a critical issue. Long-term application becomes more di cult under the condition that each sensor is equipped with limited power supply unit. Low-duty cycle wireless sensor network can reduce the energy consumption and many relative researches have been made in recent years. In this environment, the latency of sending packets from sink to each node is much longer than traditional WSNs because of nodes stay asleep most of time and wake up to receive packets in routine. Therefore, it is signi cant to nd a suitable place to put sink, which is a critical issue in the low-duty cycle WSNs. In this work, the Centralized Cluster-based Location Finding (CCLF) algorithm is proposed to reduce the high latency in the low-duty cycle WSNs environment by nding an optimal position of sink. The proposed algorithm consisted mainly of three steps. First, cluster organization and establishment for the environment is performed. Next, optimal paths between gateway nodes and its members are constructed with the help of fast look-up table (FLU-Table) for each cluster in order to achieve minimum latency. Finally, the near-optimal location of sink in the cluster is identi ed and setup. The simulation results show the performance of proposed algorithm approaching the optimal solution. Moreover, the proposed algorithm requires less operations and complexity compared with optimal solution for searching the optimal sink place.

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