時間同步在無限網路感測是一個很重要的議題，特別是在分散式測量系統。IEEE 1588標準協定是定義精確的時鐘同步協定使用在網路量測與控制。在這篇論文中，我們提出了一個Hierarchy Reference Broadcast Synchronization (HRBS)演算法，是應用在IEEE標準802.15.4上的無線感測網路。我們提出的架構結合了PTP協定和HRBS演算法，它的工作分成三個步驟：首先，網路伺服器透過GPS可以取得世界標準時間，並且使用PTP協定讓網路上其它的裝置的時間校正成和網路伺服器的時間相同。第二步驟，其中一個被PTP校正過的裝置和無線感測網路上的一個感測器相連接，並且將它的時間傳給這個感測器。我們使用HRBS將所有在無線感測網路上的感測器做時間同步，我們使用Linux主機和Chipcon CC2430 Demonstration Kits開發平台來做實驗，最後我們分析PTP和HRBS的準確率和效能評估。發展成一個基於PTP下的分散式無線感測網路測量系統。

Time synchronization is an important aspect in wireless sensor networks, especially in distributed measurement system. IEEE 1588 is a standard for precise clock synchronization for network measurement and control systems in LAN environment. In the thesis, we present a time synchronization mechanism, named Hierarchy Reference Broadcast Synchronization (HRBS), for wireless sensor networks based on IEEEE 802.15.4 standard. The proposed system architecture is a hybrid of PTP protocol and HRBS algorithm. It works in three steps. In the first step, the Internet server receives the UTC (universal time coordinated) time from GPS. PTP synchronization is used to translate its clock value to the server’s clock by other devices in LAN. The second step, one of the synchronized devices is connect to the sensor node in the wireless sensor network. The synchronized device sent its time stamp to this sensor node. We use HRBS protocol to synchronize all sensor nodes clock in the wireless sensor network. Our implement is using the Linux PCs and Chipcon CC2430 Demonstration Kits. In the finally, we evaluate the PTP and the HRBS time synchronization accuracy and performance. We develop into a wireless s ensor network base on the distributed measurement system under precise time protocol.

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