基於 CoAP 觀測協定之物聯網多感測器監測機制之研究

近年來，物聯網(IoT)因為感測技術與網路通訊科技的成熟而有顯著的發展趨勢。隨著感測器成本越來越低，目前已經有大量具備網路連線能力的感測器佈建在我們的生活環境之中。而這些感測器通常卻僅有少量的儲存空間與有限的計算能力，如果將傳統的 HTTP 協議應用在物聯網上就顯得過於龐大且不適用。因此，如何在資源受限的設備與網路環境中實現 REST 架構、並降低訊息交換過程中能源的耗損便是物聯網普及化的首要課題之一。本論文利用 IETF 所制定的標準通訊協定 CoAP 之觀測(Observe)功能提供一套支援多感測器監測機制的系統架構。並依此系統架構實作出一款能支援多人線上遠端監控環境數據的監測管理系統，使在受限網路環境下的伺服器與裝置能在網際網路上被使用，有效降低頻寬需求與延遲，並提高傳輸的可靠性，確保用戶端與服務端即時的資料一致性。

關鍵字

IoT ； CoAP ； Observe ；多感測器監測

並列摘要

In recent years, the advance of sensing technology and network communication technology brings the wide development of Internet of Things (IoT). As the cost of a sensor becomes lower, it can be found that there are such a great number of sensors are deployed around us. For saving powers, most of these sensors usually only have a small amount of memory space and limited computing capability. Accordingly, the popular HTTP web protocol cannot be directly adopted as the standard protocol for use in IoT environment. Therefore, An important issue to support a Representational state transfer (REST) interface for popularizing IoT is how to reduce energy consumption during the message exchanges among resource-constrained IoT devices in a constrained network environment. For the purpose, Internet Engineering Task Force (IETF) develops Constrained Application Protocol (CoAP). Recently, IETF further develops the Observe extension of CoAP to reduce the number of message exchanges. Current Observe extension was designed for the monitoring of a single sensor. In this thesis, we will propose a multi-sensor monitoring scheme based on the CoAP Observe extension. Furthermore, following the multi-sensor monitoring scheme, we develop an IoT monitoring management system that allows online remote monitoring of environmental data by multiple users. It will be demonstrated that all the servers and devices can effectively operate in a constrained network environment with low bandwidth usage and delay. As a consequence, the reliability of IoT data transmission can be improved and the immediate consistency between servers and clients can be ensured.