觀測者透過無線感測網路來蒐集所需的感測值，藉由搜集到的感測資料對觀測的事件狀態做出判斷。而傳統的感測網路在傳送層上採用UDP-Type的傳輸協定，而UDP-Type的協定在傳送上不具有可靠性，因此傳送的過程中封包可能發生遺失，當過多的資料遺失時會影響到觀測者對於事件狀態判斷的正確性，因此為了提升事件檢測的可靠性，我們希望藉由調降感測節點的傳輸時間間距值，使得感測節點能多次的傳送封包，進而提升封包到達目的端的機率。但是大量地傳送封包，可能引發網路發生阻塞的情形，而阻塞的發生將會造成封包的丟棄，反而降低了封包到達目的端的機率，但UDP-Type的傳輸協定中缺乏阻塞的判斷機制，無法在網路發生阻塞時，通知在事件範圍內的感測節點調高其傳輸時間間距值來減緩阻塞的情形。　　　
　　因應此需求，事件到目的端可靠的傳輸協定被提出。此協定藉由調控在事件範圍內感測節點的傳送時間間距值，使得在每個事件決定區間目的端所接收的封包數能達到觀測者所希望的封包總數，且此協定包含判斷阻塞的機制，能在網路發生阻塞時，調高在事件範圍內感測節點的傳送時間間距值，減緩阻塞的情形。但此協定，是在每個事件決定區間結束時，由目的端依據所接收到的封包總數計算出新的傳輸時間間距值，再由目的端傳送訊息通知事件範圍內感測節點的方式，而此方式下目的端所傳送的訊息數量將會與事件範圍內的感測節點個數成正比，一旦事件範圍內的感測節點個數過多時，就有着控制負擔過重的問題，而由於調控節點傳輸時間間距的時機是在每個事件決定區間結束時，因此即使發現所設定的傳輸時間間距過小時，引發阻塞，都必須等到此輪事件決定區間結束後才能做處理所以有著處理傳輸上阻塞問題過慢的缺點。
　　因此本論文為了改善上述的缺點，提出新的事件到目的端的傳輸協定。我們改由受事件觸發的感測節點以固定的比率調降其傳送時間間距，不需要由目的端去計算新的傳送時間間距值再發出訊息通知，因此節省目的端花費在傳送訊息的負擔。而在處理傳輸上阻塞問題過慢方面，我們改採在每個感測節點上，運算我們所推導出的判斷阻塞公式，監測是否發生阻塞的情形。一旦發生阻塞即通知來源端的節點，而接到訊息的來源端節點會將傳送時間間距值設回預設的初值，而不是等到事件決定區間結束時才做處理，因此解決處理阻塞問題過慢的缺點。另外我們採取一個以優先權為基準的封包丟棄機制。此機制的主要作用，在於當節點因阻塞發生必須丟棄封包時，會保留對於觀測者較為重要的感測值，藉此提升新協定對於事件檢測的可靠性。在模擬中，我們透過溫度監控系統的情境假設證明不論是在網狀拓樸下或是隨機產生的拓樸下和多重事件下，都能依據觀測者的要求達成觀測者所需的事件檢測可靠度，且和之前研究者所提出的方式相較之下，我們所提出的方式使用較少的控制訊息且將封包被丟棄機率由百分之八降低到百分之五，約改善了百分之三十七。而因減少使用控制訊息和降低封包被丟棄的機率，使得我們所提出的方式，能讓每個感測節點平均可以減少百分之五的耗電量

The observer obtains information collected by the sensor network about phenomenon. The observer decides event features based on the collective reports by the sensor network. Transport protocol in transport layer of wireless sensor network is UDP-type. But UDP-type transport protocol is not reliable in the transmission. Therefore it is possible to occur loses when packets are delivered to the sink. It can affect observer regarding the accuracy of deciding event features when there are too many lost packets. In order to enhance the reliability of detecting event features, we hoped the affiliation by reducing the transmission time interval of sensor nodes. So sensor nodes can deliver packets many times and promote the probability that packets are successfully delivered. But deliver packets massively, it is possible to cause the network congestion. It could cause packets to drop during network congestion and reduce the probability that packets are successfully delivered. But UDP-type transportprotocol lacks of a congestion control mechanism. It is unable
during network congestion situation to inform sensor nodes in the event scope to adjust their transmission time interval to a longer time for relieving the congestion situation.
In accordance to this demand, event-to-sink transport protocol was proposed. This protocol affiliation by the regulation transmission time interval of sensor node enables the packet number which sink received to achieve the observer hoped total number of packets at each duration to decide event features. This protocol contains a congestion control mechanism. It can be during network congestion to inform sensor nodes in the event scope to adjust their transmission time interval to a longer time for relieving the congestion situation. The sink calculated the updated transmission time interval by all of the packets which sink received at the end of decision interval. The sink sent control messages to sensor nodes in the event scope and updated their transmission time interval. There are two disadvantages of this method. One is that it needs too many control messages and the other is that it needs a long time to resolve the congestion.
In this thesis, we propose a new event-to-sink reliable transport protocol for improving the above shortcoming. We let source nodes to reduce their transmission time interval by a fixed ratio. It doesn’t need that the sink calculated the updated transmission time interval and sent control messages to sensor nodes in the event scope,
therefore We reduced the control overhead. We use a congestion detection mechanism based on local buffer monitoring in sensor nodes. When sensor nodes detect the congestion, they send control messages to inform source nodes the congestion immediately. Source nodes which receive the control message set their transmission time interval to the initial value. By this method, we improve the shortcoming that it needs a long time to resolve the congestion in the network. Furthermore, we use a priority-based early dropping mechanism. The purpose of this mechanism is that it can save the packets with high priority when sensor nodes need to drop packets. We simulate an application for monitoring temperature in our simulation.And the simulation results show that our transport protocol can achieve the event reliability
which the observer needs in grid network topology , in random network topology, as well as under multiple concurrent events. Our protocol reduces the control overhead and the dropping probability is improved form 8% to 5% compared with other transport protocol. We can save 5 % of the energy consumption in each sensor node because our method reduces the control overhead and the dropping probability.

中文摘要…………………………………………………………………… III
Abstract……………………………………………………………… V
誌謝…………………………………………………………………VIII
表格列表………………………………………………………………XI
圖案列表:……………………………………………………………XII
Chapter 1簡介…………………………………………………………1
1.1背景……………………………………………………………… 1
1.2事件觸發的感測網路………………………………………………2
1.3論文組織架構………………………………………………………4
Chapter2相關研究…………………………………………………… 6
2.1可靠傳輸協定………………………………………………………6
2.1.1終端到終端可靠…………………………………………………6
2.1.2事件到目的端可靠………………………………………………8
2.2感測值加入優先權…………………………………………………9
2.3阻塞問題和判斷阻塞的指標………………………………………10
2.3.1判斷阻塞指標……………………………………………………11
2.4研究動機……………………………………………………………14
Chapter 3新事件到目的端可靠傳輸協定……………………………16
3.1封包結構……………………………………………………………16
3.2傳輸協定的概要說明………………………………………………18
3.3傳輸協定在感測節點的運作………………………………………19
3.3.1以優先權為基準的早期丟棄機制………………………………20
3.3.2節點調降傳送時間間距的方式…………………………………21
3.4感測節點的狀態二…………………………………………………22
3.5感測節點的狀態三…………………………………………………23
3.5.1判斷阻塞公式……………………………………………………24
3.5.2計算來源節點個數的演算法……………………………………27
3.6傳輸協定在目的端的運作…………………………………………34
3.7傳送協定的執行時序圖……………………………………………35
3.8多重事件下所提出傳送協定的運作………………………………36
Chapter 4模擬與分析…………………………………………………39
4.1模擬環境……………………………………………………………39
4.2模擬結果與分析……………………………………………………41
4.2.1網狀網路拓樸……………………………………………………41
4.2.2隨機產生的網路拓樸……………………………………………52
4.2.3多重事件發生……………………………………………………58
Chapter 5結論與未來工作……………………………………………66
參 考 文 獻……………………………………………………67

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