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標題: | 物聯網中智慧且可靠之氾濫式傳播機制 Smart Reliable Flooding for Internet of Things (IoT) |
作者: | Nai-Syuan Li 黎乃瑄 |
指導教授: | 周俊廷(Chun-Ting Chou) |
關鍵字: | 物連網,可靠性多點跳躍通信,隱性確認,冗餘傳輸, Internet of things (IoT),reliable multi-hop communications,implicit acknowledgment,redundant transmissions, |
出版年 : | 2019 |
學位: | 碩士 |
摘要: | 物聯網(IoT)是由許多嵌入感測器、軟體以及連網能力的實體物件所構成的網絡。其允許物件透過網路進行遠程感測和控制。因此,網路中的物件可以相互溝通並彼此合作以達成共同目標。在許多種類的物聯網應用中,其中某些應用需要高度的可靠性,例如基於物聯網的醫療保健系統,智慧工廠等等。
在本篇論文中,我們的目標是專注在基於物聯網的應用中的可靠性多點跳躍通信(reliable multi-hop communications)。在典型的物聯網網路中,不同的應用會產生不同的資料傳播模式。物聯網的資料傳播模式可以是單點跳躍(one-hop)或多點跳躍(multi-hop)。根據源節點和目的節點的數量不同,可以將多點跳躍進一步劃分為三種類型,包括:一對一(one-to-one),一對多(one-to-many)和多對一(many-to-one)。雖然許多現有的路由協定已經針對不同的資料傳播模式提出解決方案,但考慮到計算複雜度和儲存空間的限制,我們無法在單一設備中同時實現多個協定。因此,我們採用帶有隱性確認(implicit acknowledgment)的簡單泛洪simple flooding機制作為我們的基準通信協定。此協定雖然可以保證高度可靠性,但其產生的冗餘傳輸則會是另一個挑戰。而我們的目標是提出一個方法以支持三種資料傳播模式,並在保證可靠性的同時最小化冗餘傳輸。 我們提出了三種解決方案來處理基準通信協定中的冗餘傳輸問題。首先,我們在各裝置端引入Neighbor Information Bitmap(NIB)的概念讓裝置間彼此分享各自鄰近裝置是否已經傳送特定訊息的資訊,這解決了由帶有隱性確認的簡單泛洪機制引起的冗餘傳輸。其次,我們讓裝置採用方向性泛洪(Directional Flooding(DF))的機制,讓試圖轉傳的裝置可以透過源節點和目的節點之間的跳躍數來了解傳送訊息的方向,這解決了由全向性泛洪(Omni-directional flooding)引起的冗餘傳輸。最後,我們讓裝置採用跨層考量(Cross-layer Consideration(CLC))的概念來了解應用層接收訊息的順序,從而解決由更高層的重傳機制引起的冗餘傳輸。 為了評估我們的解決方案在真實環境中的表現,我們在台灣大學博理館設置了由一個閘道器和39個終端設備組成的測試平台。實驗結果顯示不論在通道負載高或是低的情況下,NIB平均分別減少49%和58%的冗餘傳輸,NIB加上DF平均分別減少86%和81%的冗餘傳輸,NIB加上DF以及CLC平均分別減少98%和85%的冗餘傳輸。最重要的是,在所有情況下,我們可以保證至少97%的可靠度。 Internet of things (IoT) is the network of physical objects which are embedded with electronic hardware such as sensors, software and network connectivity. IoT allows objects to sense and to be controlled remotely across networks. As result, they can interact with each other and cooperate with their neighbors to reach common goals. Among variant objectives of the IoT applications, high reliability is required in many applications such as IoT-based healthcare system, smart factories, etc. In this thesis, our objective is to focus on reliable multi-hop communications in IoT-based applications. In a typical IoT network, different applications generate a wide range of traffic patterns. The traffic patterns of IoT can be either single hop or multi-hop. The multi-hop traffic can be further divided, depending on the number of source and destination nodes into three types of patterns including: one-to-one, one-to-many, and many-to-one. Although many existing routing schemes have been tailored for different traffic patterns, given the limitation of computing and storage, we cannot implement multiple schemes in a single device. Therefore, we adopt a simple flooding with implicit acknowledgment mechanism as baseline protocol. In this baseline protocol, reliability can be guaranteed but a redundant transmission becomes a real challenge. Our goal is to support all three patterns and to minimize redundant transmissions while guaranteeing reliability. We proposed three solutions to deal with redundant problems in the baseline. First, we introduce Neighbor Information Bitmap (NIB) for devices to share the information regarding which neighbors have relayed a given message, which resolves the redundancy caused by simple flooding implicit acknowledgement. Second, we propose Directional Flooding (DF) for devices to know the direction of the message by the hop count between the source and the destination nodes, which resolves the redundancy caused by Omni-directional flooding. Last, we propose Cross-layer Consideration (CLC) for devices to know the order of the received messages, which resolves the redundancy caused by higher-layer retransmission. In order to evaluate the performance of our solutions in real environments, a testbed composed of a gateway and 39 end devices is developed in BL building, National Taiwan University. According to our experiment results in high and low channel loads cases, NIB reduces 49% and 58% of redundant transmissions respectively on average, NIB with DF reduces 86% and 81% of redundant transmissions respectively on average, NIB along with DF and CLC reduces 98% and 85% redundant transmissions respectively on average. More importantly, in all of the cases, at least 97% reliability is guaranteed. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/73721 |
DOI: | 10.6342/NTU201903954 |
全文授權: | 有償授權 |
顯示於系所單位: | 電信工程學研究所 |
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