工業物聯網(IIoT)應用需要一個可靠、即時和節能的訊息傳遞服務。為了節省每個嵌入式 IIoT 儀器的能源消耗,從而延長傳感器的使用壽命,最好的辦法是沒有冗餘的訊息交換。本論文分析了 MQTT 訊息傳輸協議和端到端訊息傳輸之間的利弊,表明使用端到端訊息傳輸來提高可靠性時,可能存在兩個問題,即可能造成能源浪費和產生冗餘訊息。對於每一個問題,都提出了一個解決方案,並只有在必要時才進行重傳。因此,本論文提出了一個名為 E4 的訊息傳遞架構,以及它在 Mosquitto(一種開源的 MQTT 實現)上的實現。透過實際應用場景的實驗,證實了該設計的可行性。E4 訊息傳遞架構不僅提高了傳輸的可靠性,還保有傳輸的即時性。此外,因研究結果顯示了 E4 訊息傳遞架構能有效減少不必要的重傳,從而減少能源浪費,故所提出的架構適用於有節能與即時需求的 IIoT 應用。

Industrial Internet-of-Things (IIoT) applications require a reliable, timely, and energy-efficient messaging service. In order to save energy consumption at each embedded IIoT instrument, thus to prolong the sensors' lifetime, it is best that the service be free of redundant message exchanges. This thesis analyzes the pros and cons among MQTT messaging protocol and end-to-end messaging, showing that there are two possible problems when using end-to-end messaging to improve reliability, which could cause energy waste and produce redundant messages. For each problem, a solution is proposed to make re-transmissions only when necessary. Accordingly, this thesis proposes a messaging architecture called E4, along with its implementation upon Mosquitto, an open-source MQTT implementation. Experiments with a practical application scenario has confirmed the feasibility of the design. The E4 messaging architecture not only improves transmission reliability but also maintains real-time delivery. In addition, the results suggest that by reducing unnecessary re-transmissions, E4 is effective in terms of energy saving. The proposed architecture could be a good support to many IIoT applications.

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