利用行動錨節點之同心信標重疊定位法於無線感測網路之定位研究

A Study of Using Mobile Anchor with Concentric Beacons Ring Overlapping Localization for Wireless Sensor Networks

沈子惟(Zih-Wei Shen)

指導教授 ： 李俊賢

國立臺北科技大學/電資學院/電機工程系研究所/碩士(2014年)

摘要

現今無線感測網路的應用中，感測節點的位置訊息在收集環境資訊時是一個不可或缺的關鍵。因此，為了有效估測出感測節點的位置，許多的定位方法開始陸續被提出。大部分的定位方法的定位精準度都取決於錨節點的數量，所以一旦在低密度錨節點的環境下，就會發生定位精準度下降或是無法定位的問題。於是有學者提出利用移動錨節點來輔助定位方法解決上述問題，但是此方法卻受到移動間距以及環境邊界的影響導致定位精準度下降。
因此，本論文以同心錨信標(concentric anchor beacons, CAB)定位為基礎，提出使用移動錨節點並結合網格掃描算法的同心圓重疊定位法。此方法不需要在環境中佈署大量的固定錨節點，僅需利用單一的移動錨節點在環境中廣播訊號。移動錨節點在移動過程中會連續廣播多個不同功率強度的訊號。盲節點會根據接收到的功率強度訊號來判斷自身所在的環形區域，接著透過多個環形區域的交集找到重疊區域。最後利用最小最大搜索演算法在重疊區域上計算出估測矩形，並在此估測矩形上使用網格掃描算法作位置估測。本文提出的方法，除了使用單一的移動錨節點外，並且利用同心錨信標定位結合網格掃描算法解決了定位誤差受到移動間距以及環境邊界影響時的問題。因此，能夠在低密度錨節點的環境下，成功同時改善定位精準度以及定位覆蓋率。

關鍵字

無線感測網路 ； 定位 ； 最小最大搜索演算法 ； 同心錨信標 ； 網格掃描算法

並列摘要

Nowadays in terms of application of wireless sensor network (WSN), sensor nodes location information is essential for collecting environmental information. Therefore, in order to estimate effectively the position of sensor nodes, many localization methods have been proposed. Localization accuracy of most of the localization method ones depends on the number of anchor nodes; thus if an environment is with low-density anchor node, the problem of decreased localization accuracy or failure of localization will occur. In this regard, some scholars propose to use mobile anchor node to improve localization methods in order to solve the problem. However, their methods are limited due to beacon distance and environmental boundary which leading to the decrease the localization accuracy.
To this end, based on the concentric anchor beacons (CAB) localization, this paper proposes the concentric beacons overlapping localization method which utilizes mobile anchor node and combining grid scan. This method need not deploy a large number of fixed anchor nodes in the environment; instead, it only uses a single mobile anchor node to broadcast signals in the environment. A mobile anchor node continuously broadcasts a number of signals at different transmission power levels of in the process of moving. Blind nodes confirm their annular region based on the received signals of transmission power levels, and afterwards, blind nodes find the overlapping region by way of a number of annular regions intersecting. Finally, Min-max method produces estimative rectangle on the overlapping region, and uses grid scan for position estimation on this estimative rectangle. Our method, which includes a single mobile anchor node and utilizes the concentric beacons localization combining grid scan to solve the problem of localization error caused by beacon distances and environmental boundary affect. To sum up, this study successfully improves the localization accuracy and localization coverage in the environment with low-density anchor node.

並列關鍵字

Wireless Sensor Network ； Localization ； Min-max method ； Concentric Anchor Beacons ； Grid Scan algorithm

參考文獻

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