Smart Data Dissemination Scheme of VANET on Highway

隨著車用無線隨意網路(Vehicular Ad hoc Networks, VANET)這個研究議題發展至今，有相當多種應用被提出，最主要分為兩種類型，第一種類型是為了增加行車的安全，第二種類型是讓旅途更順利，舉例來說，像是道路流量的監測、旅遊指引、警示訊息的散佈等等，在這邊我們可以發現大多數VANET上的應用，都與資訊散佈有緊密的關係，因此資訊散佈在車用無線隨意網路中是一個重要的研究議題，對於資訊的散佈，在傳統隨意網路(Mobile Ad hoc Networks, MANET)中研究相當多，但是由於車用隨意網路與傳統隨意網路，存在不同的網路特性，使得在許多研究議題上，傳統的方式並不能直接被採用。在本文當中，對於資訊散佈，我們主要分成資料的推和挽兩種模型討論，首先在推模型中，指的是位於散佈區域內的車輛都需要強制接收資料，我們針對資料想要散佈在高速公路環境特定區域的應用，提出以車用網路特性為基礎的資料散佈方法，在此方法中，可以有效率的將資料散佈到區域內，接著我們加強提出來的方法，使資訊不只是能有效率的被散佈在空間中，也具備有時間性，有效的提供資訊給將要進入特定區域內的車輛。其次在挽模型中，資料並不強制車輛一定要接收，而是指車輛會向前方特定區域查尋資訊的問題，在解決這個問題時，我們提出了不同於傳統隨意網路上解決的方法．最後在模擬結果中可以看出透過我們提出的方式，在推和挽的模型中，我們可以大量的降低不必要的資料負荷，並且在面對不同的交通情況下，我們提來的方法皆有不錯的表現。Along with the development of the VANET (Vehicular Ad hoc Networks), till now, many kinds of applications are proposed. There are two types separated. The first type is to improve the driving safety; the second one is to have a comfort experience while driving. We can find most of the applications, for instance, the traffic flow monitoring, tourist guidelines, and warning message dissemination, etc., have close relationship with data dissemination in VANET, so data dissemination is an important research issue in VANET. About data dissemination, there are lots of researches in traditional MANET (Mobile Ad hoc Networks); however, there are different characteristics existing between the VANET and MANET so that traditional methods can not be applied directly in many research issues. In this thesis, we mainly divide the data dissemination into the push and the pull model of data to discuss. First, in the push model, cars in the determinant area should be received data compulsorily. We focus on the application of disseminating in the determinant area on highway, proposing the method of data dissemination based on the vehicular network characteristics. In this method, we can disseminate data efficiently to the determinant area, and then improve the method we proposed so that the information disseminates not only efficient but time-keeping, providing information efficient to the coming vehicles into the determinant area. Second, in the pull model, cars are not necessary to receive data compulsorily, but the problem of searching data toward the determinant area. At last, according to the simulation result, our methods degrade the dissemination of unnecessary information in the push and the pull model, and have good performance when facing variant traffic conditions.口試委員會審定書.....................................................................................Ⅰ 致謝.............................................................................................................Ⅱ 中文摘要.....................................................................................................Ⅲ 英文摘要.....................................................................................................Ⅳ 第一章 緒論.................................................................................................1 1.1 研究背景.........................................................................................1 1.2 研究目的.........................................................................................4 1.3 論文結構.........................................................................................5 第二章 文獻探討.........................................................................................6 2.1在MANET上的資料散佈研究......................................................6 2.2在VANET上的資料散佈研究.......................................................7 第三章 資料散佈方法...............................................................................10 3.1推模型中資料散佈方法的假設....................................................10 3.2推模型中資料散佈方法的介紹....................................................11 3.2.1節點的運作..........................................................................11 3.2.2資料散佈判斷......................................................................12 3.2.3資料散佈方法遭遇的邊界問題..........................................13 3.2.4 降低資料傳送負荷的方法.................................................15 3.2.5決定控制訊息的週期..........................................................16 3.3挽模型中資料散佈方法的假設....................................................17 3.4挽模型中資料散佈方法的介紹....................................................18 第四章 模擬結果與討論................... .......................................................20 4.1 推模型中模擬環境的設定...........................................................20 4.2 推模型的模擬結果與分析...........................................................22 4.2.1資料傳送的比例..................................................................22 4.2.2資料傳送的負荷..................................................................24 4.2.3 資料平均的接收時間.........................................................26 4.2.4 即時資料的傳送.................................................................26 4.3挽模型中模擬環境的設定............................................................28 4.4挽模型的模擬結果與分析............................................................29 4.4.1資料傳送的負荷............ .....................................................29 4.4.2 資料平均的接收時間......... ...............................................29 第五章 結論.................................... ..........................................................32 參考文獻............................. .......................................................................3