在無線感測網路的應用中，感測節點的定位是主要的關鍵基礎技術之一，例如在環境偵測、火災偵測、物件追蹤、戰場監控等許多應用均需要獲取位置資訊，否則所收集到的數據便沒有意義。雖然使用GPS (Global Positioning System)是一種很好的定位方法，但為所有節點安裝GPS接收器將造成感測節點額外的耗電，也會有較高的硬體成本[3,4]。有研究學者[6-8]提出利用裝備GPS的移動錨節點來幫助網路中的節點定位，移動錨節點行走於感測區域並週期性發送位置訊息，其作用等同於設置了大量的靜態參考點，大大降低定位系統的成本。
移動錨節點的路徑規劃可以是靜態或動態的[12,19,20]。靜態路徑是事先規劃好的路線，而動態路徑則是根據當時感測節點的實際分布情形來決定移動錨節點的移動路線。Li等人[17]提出了移動錨節點的動態路徑規劃方法(SPNP)，根據移動錨節點其通訊範圍內已知大概位置之感測節點的鄰居數目，決定下一個要移動的位置，其中感測節點的鄰居包含已定位的和未定位的，但實際上已定位的鄰居已經不需要錨節點協助定位。本文改進SPNP，先將錨節點通訊範圍劃分成六個區域，再分別計算六個區域之未定位節點數量，已定位感測節點均不納入計算。模擬結果顯示相較於SPNP，本文所提出的方法可以增加已定位節點的比率，改善定位效率。

In the application of wireless sensor networks (WSNs), localization/positioning of sensor nodes is one of the key technologies. We need to know the event location in many applications such as environmental observation, fire detection, object tracking, and military monitoring; otherwise it is useless even the event was detected. It is a good way to get the coordinate of sensor nodes by using GPS (Global Positioning System). However, equipping GPS for each sensor node will consume more energy and increase more costs[3,4]. Some researchers[6-8] present a solution to overcome this problem. They use mobile anchors that are equipped with GPS to help all the sensor nodes to locate. The mobile anchors move along the sensing area and broadcast the position information periodically. A mobile anchor can be treated as a replacement of plenty of static sensors that are equipped with GPS, greatly reducing the cost of sensor positioning.
The path planning of mobile anchors can be either static or dynamic[12,19,20]. A static path is decided before any localization action; however, a dynamic path is determined in real-time based on the real distribution of sensors nodes. Li et al. presented a dynamic path planning method of mobile anchor called SPNP[17]. The mobile anchor decides the next position according to the amount of neighbors of sensor nodes whose positions are known roughly in mobile anchor’s communication range. The neighbors of sensor nodes include localized and unknown. But actually, localized neighbors do not need the help of anchor to localize. In this paper, we improved SPNP by dividing anchor's communication range into six regions and calculate the amount of unknown sensors in each region. The localized sensors are not taken into account. Simulation results show that compared to SPNP, the mobile anchor can increase the percentage of localized sensors and localize them effectively.

論文審定書 i
誌謝 ii
摘要 iii
Abstract iv
目錄 v
圖次 viii
表次 x
字母縮寫對照表 xi
第一章 導論 1
1.1 簡介 1
1.2 研究動機 2
1.3 論文架構 4
第二章 相關研究 5
2.1 計算感測節點位置之基本方法 5
2.1.1 三邊測量法 5
2.1.2 三角測量法 6
2.1.3 極大似然估計法 7
2.2 Range-based定位方法 8
2.2.1 接收訊號角度定位法(AOA) 9
2.2.2 訊號傳播時間定位法(TOA) 10
2.2.3 訊號到達時間差定位法(TDOA) 11
2.2.4 接收訊號強度定位法(RSSI) 12
2.2.5 Range-based定位方法之比較 13
2.3 移動錨節點輔助定位 14
2.3.1 移動錨節點之靜態路徑規劃 15
2.3.2 移動錨節點之隨機移動路徑 17
第三章 系統架構與運作 24
3.1 網路的架構及條件假設 24
3.2 定位演算法 26
3.3 錨節點路徑規劃 27
3.3.1 未知節點之演算法 27
3.3.2 錨節點之演算法 27
第四章 模擬結果與討論 44
4.1 模擬環境假設 44
4.2 模擬環境參數設定 44
4.3 模擬數據分析與討論 45
4.3.1 已定位節點比率 46
4.3.2 錨節點通訊半徑對已定位節點比率的影響 47
4.3.3 感測節點密度對已定位節點比率的影響 48
4.3.4 模擬總結 49
第五章 結論 50
參考文獻 51

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