車輛在行進時，不會漫無目的的在道路上移動，透過這些有限行為能力的車輛和道路旁的路側單元所組成的網路，被稱之為車載網路 (Vehicular ad-hoc network)，車載網路被提出的目的，最主要是用於提升用車安全，避免意外事故發生，在研究車載網路時，一套新的傳輸機制、或是新的行車導航設計，在未經過模擬測試之前，是無法被大眾所使用的，所以當我們研究車載網路時，一個可以產生貼近於現實車載網路環境的模擬器是十分重要的。車載網路的研究者，最常設計的傳輸方式大多應用在都市或郊區，然而，在知名的網路模擬器ns-3上，並沒有都市或郊區的車載網路模擬環境，所以我們希望能夠在ns-3建立車載網路的模擬環境，並且能夠真實的反應出車輛在現實環境中的行為模式。本論文所提出之VanetURSim主要能讓使用者模擬車輛的現實移動行為模式，像是遵守基本的交通規、紅燈停、綠燈行，並且車輛會依照規畫好的軌跡移動，VanetURSim提供了車子的移動模組與含有紅綠燈的都市道路環境，使用者可以透過VanetURSim簡易的在ns-3上創建車載網路環境。另外，我們提出了在路側單元與車輛傳輸時流量排程的方法，利用機率的方式計算，挑選最適合協助傳輸的車輛，以此來減少能量的消耗。

Vehicles will not randomly move without purpose, Vehicular ad-hoc network (Vanet) is comprised of these vehicles and road-side units (RSU). The purpose of Vanet is to promote driving safety and avoid accidents. While studying Vanet, a new routing protocol or a guidance system is not allowed to use before testing and verifying. Thus, when studying Vanet, a critical aspect is the need for a mobility model which reflects, as close as possible, the real behavior of vehicular traffic. Researchers of Vanet generally design routing scheme for urban or suburban networks. However, ns-3 do not support urban or suburban Vanet environment networks. As a result, we want to create Vanet environment networks in ns-3, which can greatly reflect the real behavior of vehicles. Our VanetURSim primary target is to simulate real behavior of vehicular traffic. For example, obeying traffic rules, red light stop, green light move and vehicles will move along planning trajectories. VanetURSim support vehicle moving module and urban road networks with traffic lights. In addition, we proposed a traffic scheduling method between RSUs and vehicles. To saving transmission energy, we choose the most appropriate vehicle to assist forwarding through probabilistic calculating.

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