一套適用於無線車輛通訊網路研究的網路與交通模擬器

Abstract

當智慧型運輸系統的概念對全世界展示出其改善交通運輸品質與效率的潛力後，工業界與學術界對於可應用於智慧型運輸系統的技術一直都抱持著高度的興趣。直到現今，智慧型運輸系統已經發展成為一個非常熱門的研究領域，也已經有許多在日常生活中的實際應用，例如常見的車上廣播電視、車上衛星導航、車上電子自動收費系統等等，這些應用不僅為智慧型運輸系統的成功做了見證，相信在未來日子裡，更多相關領域的研究也將陸續地投入去發展更新穎與便利的應用。

智慧型運輸系統的目標，是利用將資訊與通訊科技(例如各式各樣的無線網路技術)加到基礎運輸建設與車輛上，以達到改善車輛與行人安全、增加運輸效率、提供車上娛樂等目的。舉例來說，透過車輛間互相交換自己的地理位置、移動方向與移動速度的訊息來達到碰撞的預警，透過參考及時路況的車輛導航系統來降低行車時間與燃料消耗，透過電子式自動收費系統來增加行車的流暢性，透過數位電視廣播提供給車上乘客各種的視聽娛樂，以及車上的網際網路連線服務等等都是這一類型的應用。

可以肯定的，任何應用在實際部署以提供服務之前，一定得經過某些程度的測試來證實其可行性。而對於測試上述類型的應用，在實際的道路環境中做測試通常是為了獲得可信的測試結果所必須的。然而，這樣的測試有時會需求大量的車輛與人力，有時會需要能穩定控制的車輛駕駛路徑等等，這些特性可能會需要昂貴的花費，或是使測試人員在測試的過程中處於有潛在危險的環境裡，更甚者，由於非測試人員所駕駛的其他車輛並不會配合測試而做出特定的移動方式，某些要求特定車輛相對移動方式的測試在實際的道路環境中是很難準確控制的。有鑑於此，為了消除或減輕以上所提到在測試中所可能遭遇的困難，利用模擬工具便成為一種可以取代或是輔助實地測試的一種選擇。

在此論文中，我們將介紹一套適用於無線車輛通訊網路研究的網路與交通模擬器。此模擬器整合了網路通訊協定的模擬能力與車輛移動行為的模擬能力。前者包括TCP/IP、UDP/IP、IEEE 802.16e、IEEE 802.11p等等適用於車輛網路的通訊協定，後者包括車輛於道路網路上的移動行為、車輛對於紅綠燈號誌的反應、車輛的跟車行為與車輛的變更車道行為等等。關於此模擬器的設計、實作、驗證與效能分析，都將呈現於此論文中。

Since the idea of Intelligent Transportation Systems (ITS) has shown the world its great potential to improve the quality and efficiency of transportation, intelligent transportation technologies have gained the attention from the industry and the academia. Nowadays, the research field of ITS is very popular and it’s believed that the importance of ITS will keep growing up in the future.

The goal of ITS is to apply information and communications technologies to transportation infrastructures and vehicles for improving vehicle/pedestrian safety, increasing transport efficiency, and offering in-vehicle entertainment, such as collision warning, driving guidance, electronic toll collection, digital video broadcasting, Internet access, and so on. The practical usages of these applications in our daily lives have shown us their usefulness and also given us the confidence on the viability of this kind of applications that will be applied in the future.

Certainly, any application must undergo some tests before it is deployed for service. For a vehicular application, conducting field trials in real vehicular environments is usually necessary. However, these trials are sometimes costly, hard-to-control (unrepeatable), dangerous, and even infeasible when many vehicles and people are required to involve in the trials. In this case, using simulation tools before conducting field trials or even to replace field trials is a feasible alternative to alleviate or eliminate the above problems.

This dissertation presents a network and traffic simulator that is useful for wireless vehicular communication network research. This simulator integrates the simulation capabilities of network communication protocols (e.g., TCP/IP, UDP/IP, IEEE 802.16e, IEEE 802.11p, etc.) and vehicular movement behaviors (e.g., moving on road networks, obeying traffic light signals, car following, lane changing, etc.). The design, implementation, validation, and performance of this simulator are presented in this dissertation.