Design and implementation of time synchronization in Wireless Sensor Network

[[abstract]]在無線通訊領域中，時間同步是一項重要的應用，許多無線通訊協定的技術，都 以時間同步為前提來發展其它應用方式，然而時間同步還有許多問題，已經有許多學 者提出解決的方法。在無線感測網路中，因為有限的電量、運算資源限制以及環境因 素，影響時間同步的效能。如何在達到時間同步時有效的節省資源?不使用Zigbee協 定有兩個原因:資料由網路層(Network Layer)送到媒體存取層(MAC Layer)最後送到 RF，傳輸時間不容易控制；另外，CSMA/CA的存取方式會增加封包的碰撞率，進而使 得資源被浪費。所以我們將自行開發平台克服以上的問題，在送封包之前就先讀系統 時間，這樣可以有效的減少傳輸上的延遲。[[abstract]]In the wireless communications, time synchronization is an important application. Many applications of communications protocol technology are developed with the time synchronization. However, the time synchronization still has some problems, so that there are many scholars proposed the solutions of these problems. In the Wireless Sensor Network (WSN), because of the limited electricity, limited computing resource and environmental factors, the performance of time synchronization will be affected. Therefore, how to save the resource effectively when using time synchronization is a very important thing. There are two reasons for not using Zigbee protocol: first, data from Network layer to MAC layer finally to RF, transmission time is not easy to control. Second. the access way of CSMA/CA will increase the collision rate of packet. Therefore, we will develop the platform to overcome the problems. To read system time before sending packet, it is reduce the transmission delay electricity.[[note]]碩