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感測網路與極寬頻網路的覆蓋與延展問題之研究

Coverage and Extension in Sensor and UWB Networks

作者:高宏政
畢業學校:國立成功大學
出版單位:國立成功大學
核准日期:2009-11-27
類型:Electronic Thesis or Dissertation
權限:Copyright information available at source archive--National Cheng Kung University....

中文摘要

感測網路是一個目前相當重要的研究項目。近年來由於微機電及無線通訊技術領域的快速發展,提高了微型及低成本的感測器之可行性,並適用於多樣化的應用。在已知的應用項目中,包含移動目標的追蹤及環境的監視等,都依賴了k層覆蓋(k-coverage)的感測器網路,意即,在監視區域的每一點都至少被k個感測器所覆蓋。首先,本論文提出了基於凡諾依圖(Voronoi diagram)的新型分散式自我位置估計機制以實現k層覆蓋的感測器網路。模擬結果證明此機制可以有效率地以最少數量的感測器實現感測區域的k層覆蓋,並可在三次的移動後覆蓋88%的感測區域。
能量消耗在以電池驅動的無線感測器網路也是個重要研究議題。在大多數的感測器網路中,越接近資料收集者(sink)的感測器由於需要傳送來自較遠端感測器的資料,使得它們的電力消耗較快速。因此,建立越多到達資料收集者的資料平衡路徑可以延長感測器網路的存活時間。作者在本論文亦提出了一個基於凡諾依圖的新型轉傳節點(relay node)佈置機制。此機制建立了有效的繞送路徑(routing path)以平衡感測器網路內資料流的負載,並減輕了位於資料收集者附近的感測器之電力消耗。模擬結果顯示所需的轉傳節點數量相似於Predetermined Location機制,亦少於Minimum Set Cover機制許多,且本論文提出的機制使得感測器網路之存活時間比上述的二個機制來得長。
極寬頻(UWB)是一種得以實現感測器網路應用的可行技術。在以極寬頻技術為基礎的多種感測器網路應用,包含了環境監測、邊界入侵偵測、以及視訊監控。目前已有可行的UWB技術(包含晶片及無線電模組),使用在這些感測器的網路應用。最後,本論文提出建立多跳躍(multi-hop)的隨意網路(ad hoc network)以改善使用標準(standard)所規定的多跳躍微網路(piconet)延伸機制-子(child)微網路或鄰近(neighbor)微網路。橋接裝置(bridge device)選擇機制在單一微網路中,選擇一般裝置做為橋接裝置以連接不同的微網路,並建立多個微網路之網路。本論文亦提出分散式與集中式排程機制以改善隨意網路的效能。分散式機制較為簡單且有彈性,但集中式機制能實現較佳的排程效率。模擬結果顯示,本論文提出的橋接裝置排程機制能有效率地延展UWB網路的覆蓋率。

英文摘要

Sensor network is an important issue in recent studies. Rapid advances in the micro-electronic and wireless telecommunications field in recent decades have made possible the realization of low-cost miniaturized sensor for a variety of applications. The success of many wireless sensor network (WSN) applications, such as moving target tracking and environment monitoring, is dependent upon achieving k-coverage of the sensed area, i.e. every point in the surveillance area is monitored by at least k sensors. First, this thesis presents a novel distributed self-location estimation (DSLE) scheme based on a Voronoi diagram to achieve k-coverage in a WSN with mobile nodes. The simulation results show that the proposed scheme effectively to perform k-coverage within the sensing field and fast convergent to fulfill more than 88% k-coverage ratio following three movements for the minimal required sensor deployment.
Energy consumption is also a crucially important issue in battery-driven wireless sensor networks. In most sensor networks, the sensors near the data collector (i.e. the sink) become drained more quickly than those elsewhere in the network since they are required to relay all of the data collected in the network to the sink. Therefore, more balanced data paths to the sink should be established in order to extend the lifetime of the sensor network. Also, author proposes a novel relay deployment scheme for wireless sensor networks based on the Voronoi diagram. The proposed scheme establishes effective routing paths which balance the traffic load within the sensor network and alleviate the burden on the sensors around the sink. The simulation results indicate that the number of relays deployed in the proposed scheme is similar to that deployed in the Predetermined Location scheme and is significantly less than that deployed in the Minimum Set Cover scheme. Furthermore, the lifetime of the sensor network containing relay nodes deployed using the current scheme is longer than that achieved using either the Predetermined Location scheme or the Minimum Set Cover scheme.
UWB is one of the possible technologies for applications of sensor networks. Various applications of UWB-based sensor networks including environment monitor, boundary intrusion detection, and video surveillance. The proposed systems indicate the feasibility of UWB technology (including chip and radio module) for applications of WSN. Finally, this thesis describes a framework for establishment of UWB multi-hop ad hoc networks to improve the efficiency of standard-based multi-hop extension by constructing child or neighbor piconets. Bridge devices (BDEVs) are selected from usual devices with one single network interface by a bridge selection protocol. BDEV is a member of each interconnected piconet, and used to build the multi-piconet networks. Furthermore, distributed and centralized scheduling schemes are proposed to improve the performance of the scatter ad hoc networks. The distributed schemes are simple and flexible. However, the centralized scheme could achieve better scheduling efficiency. Through simulations, the proposed BDEV scheduling schemes are shown to be effective to extend network coverage in UWB networks.


口試委員 - 林宗男

口試委員 - 林輝堂

口試委員 - 賴源正

口試委員 - 郭文中

指導教授 - 李忠憲

召集委員 - 吳承崧


 

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