無線感測網路(Wireless Sensor Networks，WSN)是由一群感測節點(sensor nodes)所組成的網路結構，感測節點將感測環境所得之資料藉由無線電波(Radio Frequency，RF)廣播到基地台(base station)。由於感測節點所感測的資料必須和位置結合，才有實用的價值，因此在無線感測網路裡估算位置變成一個重要的議題。理想上，讓每個感測節點都裝配全球衛星定位系統(Global Positioning System，GPS)便可以得到位置，然而此方法太花費成本，並與原本感測節點的低成本(low cost)目標不合。因此較合理的解決方法是讓少數感測節點擁有GPS，其餘的感測節點利用蒐集到的位置資訊，去估算出本身的位置。
本論文旨在提出跳躍數導向位置估算(Hop-Oriented Position Estimation，HOPE)演算法，四個裝配GPS的信標節點廣播跳躍數資訊，一般節點利用跳躍數資訊，搭配能在感測節點計算的簡易運算式，來獲得較準確的估算位置。

A wireless sensor network consists of a group of sensor nodes that broadcast the sensed data to the base station hop by hop via radio frequency. It is useful only if the sensed data are associated with the locations of the sensor nodes. Therefore, location estimation of sensor nodes becomes an important issue. Ideally, each sensor node can obtain its location by being equipped with a GPS device each. However, it costs too much, contradicting the object of low cost of sensor nodes. Hence, it is reasonable that few sensor nodes are equipped with a GPS device each and the others estimate their locations by collected information.
The purpose of this thesis is to propose a hop-oriented position estimation algorithm (HOPE). Four beacon nodes equipped with GPS broadcast the hop count information. Normal nodes employ the hop count information to estimate their position more closely with simple calculations.

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