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標題: | 利用鄰居資訊的移動視訊偵搜隨意網路路由法之設計與實作 Design and Implementation of Neighbor Information-based Mobile Video Surveillance Routing over Ad Hoc Networks |
作者: | Chia-Wei Chang 張家瑋 |
指導教授: | 張時中 |
關鍵字: | 移動視訊偵搜,鄰居資訊列表,路由演算法,定位,位置, mobile video surveillance,neighbor information list,routing algorithm,positioning,Location, |
出版年 : | 2007 |
學位: | 碩士 |
摘要: | 傳統視訊偵捜系統的攝影機通常會被安裝在固定位置,而且也須將影像訊號經由專用的同軸電纜回傳到監控中心。現今由於IP網路及數位取像裝置的興起,視訊影像資料可以輕鬆透過無線網路傳輸,因此激發了更多新型態移動視訊監視服務。例如將數位相機裝置在移動設備上(筆記型電腦,PDA,3G行動電話等等)所構成的監視系統,這些技術的結合促成移動式偵搜網路應用的可能性。
本論文主要研究目的是在隨意網路上實現有影像品質保證的移動視訊偵搜服務,要實現此服務首先必須要知到偵搜任務的目的地在那(座標位置),以及是否有節點在目的地附近。但由於移動的特性,每一個節點傳輸範圍內的鄰居會隨時間而不同,而所建立好的路徑也可能因node移動而損毀。此外,802.11b/g架構設計並不利於即時多媒體的傳輸。因此我們提出了兩個主要研究問題: 1. 如何週期性取得網路上其他節點的資訊 2. 如何建立並動態調整跳躍數少、能提供足夠的資料傳輸速度傳輸路徑。 我們首先利用實驗了解隨意網路傳輸即時視訊流的實際特性(hop數、距離與吞吐量的關係)後,在網路層設計了一個鄰居資訊表路由法協定,包含鄰居資訊列表交換堆疊(NIL exchange stack)和鄰居資訊路由演算法(NILRA),來解決所提出的兩個主要研究問題。其中NIL交換堆疊可以透過節點週期性相互廣播(broadcast)來保持各節點傳輸範圍內的最新鄰居資訊,包含IP 位址,經緯度位置,移動速度,方向和資料傳輸率。而路由演算法(NILRA)的主要想法是接收到取像節點搜尋要求封包的節點,如果自身與目的地之間的距離不在門檻值內,則在自身的鄰居列表裡,尋找符合傳輸速度條件的鄰居中位置最靠近目的地的節點(利用經緯度位置和傳輸速度資訊),接者將搜尋封包送給此節點。如果找不到下一個可以傳送的節點,則此節點將成為取像節點,並移動至目的地。如此類推即可尋找到一條跳躍(HOP)數較少且符合最低傳輸速度要求的路徑。而建立好的路徑上之節點也可以依照任務發起端的指令移動,進而降低傳輸路徑中斷的機率。 實作方面,我們在應用層簡易的實現鄰居資訊表路由協定。在NIL交換堆疊實做方面,利用VB.NETTM設計好的廣播(Broadcast)程式,將自身的資訊廣播出去,而其他node接收到廣播則將此資訊加入自己的NIL資料庫(SQL2000)裡。而在NILRA實做方面,使用VB.NETTM程式將建立好的NIL讀取出來,使用NILRA方法去尋找且建立傳輸路徑。最後由經由實際測量得到的數據結果,可以證明使用NILRA會比最短路徑法找到更好的影像傳輸路徑。 The cameras in traditional video surveillance system are needed to set in fixed points and connected to a central control room. With the digital camera, IP-based networking, wireless technology and IP-based video surveillance environments emerging, new video surveillance applications are inspired. For example, surveillance systems with cameras on the mobile devices (notebook, PDA, 3G mobile phone, etc) lead to the possibility of mobile video surveillance application. The focus of this thesis is to explore new and innovative mobile video surveillance services with the quality of service guaranteed. Since individual nodes can move freely on an ad hoc network, the neighboring nodes within a node’s transmission range will vary with time and the neighbors’ position information need to be updated dynamically. Currently, the protocol design of IEEE 802.11x protocols does not favor efficient multi-Hop transmission. So our two research problems are as follows: 1. How to periodically obtain neighbor nodes’ information by each node in an ad hoc network? 2. How to establish a video surveillance transmission path that uses as few hops as possible, has a minimum data rate and is reliably connected. We first conduct an experiment of real-time video streaming over an IEEE 802.11 ad hoc network to understand its transmission characteristic. We then design a neighbor information list (NIL) routing protocol of the network layer, which consists of a NIL exchange stack and a NIL routing algorithm (NILRA) to address the aforementioned two research problems. Our NIL exchange stack design includes IP address, longitude, latitude, data rate, speed, direction. It allows nodes to broadcast among each other periodically and collects neighbor’s information in the transmission range of each node. The neighbor’s information includes IP address, the position of longitude and latitude, moving speed, direction and data rate. In NILRA operations, when a node receives a route request (RREQ) originated from a source node, it checks a pre-set distance threshold carried by the RREQ. If the distance between the node and the requested destination location for video taking is not within the specified threshold, it will look for a next node in its NIL that is closer to the destination than this node and has a minimum data rate; the current node will then relay RREQ to this next node. If no closer next node can be found, this current node will be designated as the imaging taking node and move to the destination. Finally, we can establish an imaging taking path between the source node and the destination that satisfies the minimum rate requirement by this logic. In addition, the node on an established path can move according to the leader's command, and reduce the broken probability of path. We implement the design into a system prototype of the NIL routing protocol in application layer. In NIL implementation, we utilize a Broadcast program of VB.NET TM to broadcast the NIL information, and build SQL TM Database to store neighbor’s information. In NILRA implementation, we use VB.NET TM to develop the NILRA program. It can extract NIL information at each node, then search and establish a transmission path. Finally, we demonstrate that NILRA finds a better video transmission path than the one found by shortest path algorithm. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/28833 |
全文授權: | 有償授權 |
顯示於系所單位: | 電機工程學系 |
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